Alert archive / California / Excessive Heat Warnings in 2021

Excessive Heat Warning 7, NWS Phoenix, AZ

September 6, 2021La Paz County, Maricopa County, Arizona; Imperial County, Riverside County, San Bernardino County, California

NWS Phoenix, AZ issued this excessive heat warning at Sep 6, 2021, 12:12 PM MST for La Paz County, Maricopa County, Arizona; Imperial County, Riverside County, San Bernardino County, California. It took effect at Sep 7, 2021, 10:00 AM MST. It was in force for 58 hr. 13 reports came from inside the area while it was in force.

The area

The counties it named, with what was reported inside it.

The facts

Issued
Sep 6, 2021, 12:12 PM MST (19:12 UTC)
In effect from
Sep 7, 2021, 10:00 AM MST
Expired
Sep 9, 2021, 8:00 PM MST
In force
58 hr
Issued by
NWS Phoenix, AZ

Counties La Paz County, AZ, Maricopa County, AZ, Imperial County, CA, Riverside County, CA, San Bernardino County, CA

The radar

The Yuma radar (KYUX), 139 km from the middle of the area, began a volume at 19:13 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Sep 9, 12:45 PM MSTTSTM WND GST 392 E Adelanto, CAAWOS STATION KVCV VICTORVILLE AIRPORT. THUNDERSTORM TO THE EAST.
Sep 9, 1:26 PM MSTTSTM WND GST 4620 Ene Big Bear City, CAMESONET STATION MNLC1 MEANS LAKE. THUNDERSTORM WIND OUTFLOW. TEMPERATURE WENT FROM 98 TO 77F.
Sep 9, 2:17 PM MSTDEBRIS FLOW5 W Big Bear Lake, CACHP CALTRANS REPORTING ROCKS SLIDING ONTO HIGHWAY 18 ARCTIC CIRCLE DUE TO THUNDERSTORMS CURRENTLY THERE. THIS IS LOCATED NEAR THE SHARP WINDING PORTION OF THE HIGHWAY.
Sep 9, 2:21 PM MSTTSTM WND GST 4611 Ese Jtnp-Lost Horse, CAWILSON CANYON RAWS IN JOSHUA TREE NATIONAL PARK. TIME ESTIMATED FROM RADAR.
Sep 9, 2:26 PM MSTHEAVY RAIN 0.3820 Ene Big Bear City, CAMESONET STATION MNLC1 MEANS LAKE IN DESERT DRY BED.
Sep 9, 3:15 PM MSTDEBRIS FLOW5 W Big Bear Lake, CACHP CLOSURE ON HIGHWAY 18. RADAR RAINFALL OF 1 TO 2 INCHES IN 1 HOUR ON THE STEEP SLOPES AT THE WINDY PORTION OF ARCTIC CIRCLE HIGHWAY 18. ROCK SLIDES REPORTED ONTO HIGHWAY.
Sep 9, 3:15 PM MSTDEBRIS FLOW5 W Big Bear Lake, CACORRECTS PREVIOUS DEBRIS FLOW REPORT FROM 5 W BIG BEAR LAKE. CHP CLOSURE ON HIGHWAY 18. RADAR RAINFALL OF 1 TO 2 INCHES IN 1 HOUR ON THE STEEP SLOPES AT THE WINDING PORTION OF ARCTIC CIRCLE HIGHWAY 18. ROCK SLIDES REPORTED ONTO HIGHWAY.
Sep 9, 3:16 PM MSTLIGHTNING1 Ssw Mentone, CATREE ON FIRE AFTER BEING STRUCK BY LIGHTNING.
Sep 9, 3:20 PM MSTTSTM WND GST 503 Sw Calimesa, CAMESONET STATION 095SE CALIMESA (095SE) FROM CURRENT THUNDERSTORM WIND.
Sep 9, 3:20 PM MSTNON-TSTM WND GST 652 Ssw Calimesa, CAMESONET STATION SOCAL EDISON SCE038 CALIMESA (038SE) FROM THUNDERSTORM WIND. ON ROBERTS ROAD.
Sep 9, 3:30 PM MSTTSTM WND GST 454 Wnw Calimesa, CAMESONET STATION 155 SOCAL EDISON YUCAIPA CREEK FROM THUNDERSTORM WIND.
Sep 9, 4:58 PM MSTFLOOD1 E Banning, CAFLOODING REPORTED RAMSEY ST ON RAMP AND I-10 EAST.
Sep 9, 5:00 PM MSTHEAVY RAIN 1.13 Ne Mt San Jacinto, CALOWER SNOW CREEK RECEIVED 1.10 INCHES IN 1 HOUR AND 0.39 INCHES IN 15 MINUTES FROM THUNDERSTORM. RIVERSIDE COUNTY FLOOD CONTROL.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

San Diego, CA (KNKX), launched 12:00Z, 7.2 hours before the alert went out and 246 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, San Diego, CA at 12:00Z on 2021-09-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, San Diego, CA at 12:00Z on 2021-09-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 39 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1536 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
39 m²/s²
0-3 km storm-relative helicity
61 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

813 
WWUS75 KPSR 061912
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
1212 PM MST Mon Sep 6 2021

CAZ561-570-071200-
/O.NEW.KPSR.EH.W.0007.210907T1700Z-210909T0300Z/
Joshua Tree NP East-Chuckwalla Valley-
Including the city of Midland
1212 PM PDT Mon Sep 6 2021

...EXCESSIVE HEAT WARNING IN EFFECT FROM 10 AM TUESDAY TO 8 PM
PDT WEDNESDAY...

* WHAT...Dangerously hot conditions. Afternoon temperatures 105 
  to 115 expected.

* WHERE...Eastern portion of Joshua Tree National Park and 
  Chuckwalla Valley.

* WHEN...From 10 AM Tuesday to 8 PM PDT Wednesday.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$
8 follow-up statements
802 
WWUS75 KPSR 070817
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
117 AM MST Tue Sep 7 2021

CAZ561-570-072300-
/O.CON.KPSR.EH.W.0007.210907T1700Z-210909T0300Z/
Joshua Tree NP East-Chuckwalla Valley-
Including the city of Midland
117 AM PDT Tue Sep 7 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT FROM 10 AM THIS
MORNING TO 8 PM PDT WEDNESDAY...

* WHAT...Dangerously hot conditions. Afternoon temperatures 105 
  to 115 expected.

* WHERE...Eastern portion of Joshua Tree National Park and 
  Chuckwalla Valley.

* WHEN...From 10 AM this morning to 8 PM PDT Wednesday.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$
419 
WWUS75 KPSR 072028
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
128 PM MST Tue Sep 7 2021

CAZ561-570-081200-
/O.EXT.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Joshua Tree NP East-Chuckwalla Valley-
Including the city of Midland
128 PM PDT Tue Sep 7 2021

...EXCESSIVE HEAT WARNING NOW IN EFFECT UNTIL 8 PM PDT THURSDAY...

* WHAT...Dangerously hot conditions. Afternoon temperatures 104 
  to 114.

* WHERE...Eastern portion of Joshua Tree National Park and 
  Chuckwalla Valley.

* WHEN...Until 8 PM PDT Thursday.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$

AZZ537-540>544-546-548>551-081200-
/O.NEW.KPSR.EH.A.0006.210909T1700Z-210910T0300Z/
Northwest Valley-Buckeye/Avondale-Cave Creek/New River-
Deer Valley-Central Phoenix-North Phoenix/Glendale-
Scottsdale/Paradise Valley-East Valley-Fountain Hills/East Mesa-
South Mountain/Ahwatukee-Southeast Valley/Queen Creek-
Including the cities of Circle City, Surprise, Wittmann, 
Beardsley, Sun City West, Avondale, Cashion, Goodyear, Liberty, 
Scottsdale, Peoria, Phoenix, Paradise Valley, Mesa, Chandler, 
Tempe, Gilbert, Fountain Hills, Sun Lakes, and Queen Creek
128 PM MST Tue Sep 7 2021

...EXCESSIVE HEAT WATCH IN EFFECT FROM THURSDAY MORNING THROUGH
THURSDAY EVENING...

* WHAT...Dangerously hot conditions possible. Afternoon 
  temperatures 105 to 109.

* WHERE...Portions of south central Arizona.

* WHEN...From Thursday morning through Thursday evening.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Watch means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$
911 
WWUS75 KPSR 080849
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
149 AM MST Wed Sep 8 2021

CAZ561-570-082300-
/O.CON.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Joshua Tree NP East-Chuckwalla Valley-
Including the city of Midland
149 AM PDT Wed Sep 8 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM PDT
THURSDAY...

* WHAT...Dangerously hot conditions. Afternoon temperatures 104 
  to 114.

* WHERE...Eastern portion of Joshua Tree National Park and 
  Chuckwalla Valley.

* WHEN...Until 8 PM PDT Thursday.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$

AZZ537-540>544-546-548>551-082300-
/O.CON.KPSR.EH.A.0006.210909T1700Z-210910T0300Z/
Northwest Valley-Buckeye/Avondale-Cave Creek/New River-
Deer Valley-Central Phoenix-North Phoenix/Glendale-
Scottsdale/Paradise Valley-East Valley-Fountain Hills/East Mesa-
South Mountain/Ahwatukee-Southeast Valley/Queen Creek-
Including the cities of Circle City, Surprise, Wittmann, 
Beardsley, Sun City West, Avondale, Cashion, Goodyear, Liberty, 
Scottsdale, Peoria, Phoenix, Paradise Valley, Mesa, Chandler, 
Tempe, Gilbert, Fountain Hills, Sun Lakes, and Queen Creek
149 AM MST Wed Sep 8 2021

...EXCESSIVE HEAT WATCH REMAINS IN EFFECT FROM THURSDAY MORNING
THROUGH THURSDAY EVENING...

* WHAT...Dangerously hot conditions possible. Afternoon 
  temperatures 106 to 109.

* WHERE...Portions of south central Arizona.

* WHEN...From Thursday morning through Thursday evening.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Watch means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$
276 
WWUS75 KPSR 081937
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
1237 PM MST Wed Sep 8 2021

AZZ537-540>544-546-548>551-090745-
/O.UPG.KPSR.EH.A.0006.210909T1700Z-210910T0300Z/
/O.EXB.KPSR.EH.W.0007.210909T1700Z-210910T0300Z/
Northwest Valley-Buckeye/Avondale-Cave Creek/New River-
Deer Valley-Central Phoenix-North Phoenix/Glendale-
Scottsdale/Paradise Valley-East Valley-Fountain Hills/East Mesa-
South Mountain/Ahwatukee-Southeast Valley/Queen Creek-
Including the cities of Circle City, Surprise, Wittmann, 
Beardsley, Sun City West, Avondale, Cashion, Goodyear, Liberty, 
Scottsdale, Peoria, Phoenix, Paradise Valley, Mesa, Chandler, 
Tempe, Gilbert, Fountain Hills, Sun Lakes, and Queen Creek
1237 PM MST Wed Sep 8 2021

...EXCESSIVE HEAT WARNING IN EFFECT FROM 10 AM TO 8 PM MST
THURSDAY...

* WHAT...Dangerously hot conditions. Afternoon temperatures 106 
  to 109 expected.

* WHERE...Portions of south central Arizona.

* WHEN...From 10 AM to 8 PM MST Thursday.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$

CAZ561-570-090745-
/O.CON.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Joshua Tree NP East-Chuckwalla Valley-
Including the city of Midland
1237 PM PDT Wed Sep 8 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM PDT
THURSDAY...

* WHAT...Dangerously hot conditions. Afternoon temperatures 104 
  to 114.

* WHERE...Eastern portion of Joshua Tree National Park and 
  Chuckwalla Valley.

* WHEN...Until 8 PM PDT Thursday.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$
184 
WWUS75 KPSR 090454
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
954 PM MST Wed Sep 8 2021

CAZ561-570-092200-
/O.CON.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Joshua Tree NP East-Chuckwalla Valley-
Including the city of Midland
954 PM PDT Wed Sep 8 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM PDT
THURSDAY...

* WHAT...Dangerously hot conditions. Afternoon temperatures 104 to
  112 degrees.

* WHERE...Eastern portion of Joshua Tree National Park and 
  Chuckwalla Valley.

* WHEN...Until 8 PM PDT Thursday.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$

AZZ537-540>544-546-548>551-092200-
/O.CON.KPSR.EH.W.0007.210909T1700Z-210910T0300Z/
Northwest Valley-Buckeye/Avondale-Cave Creek/New River-
Deer Valley-Central Phoenix-North Phoenix/Glendale-
Scottsdale/Paradise Valley-East Valley-Fountain Hills/East Mesa-
South Mountain/Ahwatukee-Southeast Valley/Queen Creek-
Including the cities of Circle City, Surprise, Wittmann, 
Beardsley, Sun City West, Avondale, Cashion, Goodyear, Liberty, 
Scottsdale, Peoria, Phoenix, Paradise Valley, Mesa, Chandler, 
Tempe, Gilbert, Fountain Hills, Sun Lakes, and Queen Creek
954 PM MST Wed Sep 8 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT FROM 10 AM TO 8 PM
MST THURSDAY...

* WHAT...Dangerously hot conditions. Afternoon temperatures 105 to
  110 degrees.

* WHERE...Portions of south central Arizona.

* WHEN...From 10 AM to 8 PM MST Thursday.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$
207 
WWUS75 KPSR 090828
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
128 AM MST Thu Sep 9 2021

AZZ530-533-538-CAZ569-100300-
/O.EXA.KPSR.EH.W.0007.210909T1700Z-210910T0300Z/
Parker Valley-Central La Paz-Tonopah Desert-Palo Verde Valley-
Including the cities of Parker, Ehrenberg, Brenda, Harcuvar, 
Quartzsite, Vicksburg, Vicksburg Junction, Salome, Arlington, 
Hassayampa, Tonopah, Wintersburg, Blythe, Palo Verde, and Ripley
128 AM MST Thu Sep 9 2021 /128 AM PDT Thu Sep 9 2021/

...EXCESSIVE HEAT WARNING IN EFFECT FROM 10 AM MST /10 AM PDT/
THIS MORNING TO 8 PM MST /8 PM PDT/ THIS EVENING...

* WHAT...Dangerously hot conditions. Afternoon temperatures 108 
  to 112 expected.

* WHERE...In Arizona, Parker Valley, Central La Paz County and 
  Tonopah Desert. In California, Palo Verde Valley.

* WHEN...From 10 AM MST /10 AM PDT/ this morning to 8 PM MST /8 
  PM PDT/ this evening.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$

CAZ561-570-100300-
/O.CON.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Joshua Tree NP East-Chuckwalla Valley-
Including the city of Midland
128 AM PDT Thu Sep 9 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM PDT THIS
EVENING...

* WHAT...Dangerously hot conditions. Afternoon temperatures 104 
  to 115.

* WHERE...Eastern portion of Joshua Tree National Park and 
  Chuckwalla Valley.

* WHEN...Until 8 PM PDT this evening.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$

AZZ537-540>544-546-548>551-100300-
/O.CON.KPSR.EH.W.0007.210909T1700Z-210910T0300Z/
Northwest Valley-Buckeye/Avondale-Cave Creek/New River-
Deer Valley-Central Phoenix-North Phoenix/Glendale-
Scottsdale/Paradise Valley-East Valley-Fountain Hills/East Mesa-
South Mountain/Ahwatukee-Southeast Valley/Queen Creek-
Including the cities of Circle City, Surprise, Wittmann, 
Beardsley, Sun City West, Avondale, Cashion, Goodyear, Liberty, 
Scottsdale, Peoria, Phoenix, Paradise Valley, Mesa, Chandler, 
Tempe, Gilbert, Fountain Hills, Sun Lakes, and Queen Creek
128 AM MST Thu Sep 9 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT FROM 10 AM THIS
MORNING TO 8 PM MST THIS EVENING...

* WHAT...Dangerously hot conditions. Afternoon temperatures 107 
  to 110 expected.

* WHERE...Portions of south central Arizona.

* WHEN...From 10 AM this morning to 8 PM MST this evening.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$
671 
WWUS75 KPSR 091950
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
1250 PM MST Thu Sep 9 2021

CAZ561-570-100300-
/O.CON.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Joshua Tree NP East-Chuckwalla Valley-
Including the city of Midland
1250 PM PDT Thu Sep 9 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM PDT THIS
EVENING...

* WHAT...Dangerously hot conditions. Afternoon temperatures 104 
  to 115. 

* WHERE...Eastern portion of Joshua Tree National Park and 
  Chuckwalla Valley. 

* WHEN...Until 8 PM PDT this evening.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$

AZZ530-533-538-CAZ569-100300-
/O.CON.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Parker Valley-Central La Paz-Tonopah Desert-Palo Verde Valley-
Including the cities of Parker, Ehrenberg, Brenda, Harcuvar, 
Quartzsite, Vicksburg, Vicksburg Junction, Salome, Arlington, 
Hassayampa, Tonopah, Wintersburg, Martinez Lake, Blythe, 
Palo Verde, and Ripley
1250 PM MST Thu Sep 9 2021 /1250 PM PDT Thu Sep 9 2021/

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM MST /8 PM
PDT/ THIS EVENING...

* WHAT...Dangerously hot conditions. Afternoon temperatures 108 
  to 112 expected. 

* WHERE...In Arizona, Parker Valley, Central La Paz County and 
  Tonopah Desert. In California, Palo Verde Valley. 

* WHEN...From 10 AM MST /10 AM PDT/ this morning to 8 PM MST /8 
  PM PDT/ this evening. 

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$

AZZ537-540>544-546-548>551-100300-
/O.CON.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Northwest Valley-Buckeye/Avondale-Cave Creek/New River-
Deer Valley-Central Phoenix-North Phoenix/Glendale-
Scottsdale/Paradise Valley-East Valley-Fountain Hills/East Mesa-
South Mountain/Ahwatukee-Southeast Valley/Queen Creek-
Including the cities of Circle City, Surprise, Wittmann, 
Beardsley, Sun City West, Avondale, Cashion, Goodyear, Liberty, 
Scottsdale, Peoria, Phoenix, Paradise Valley, Mesa, Chandler, 
Tempe, Gilbert, Fountain Hills, Sun Lakes, and Queen Creek
1250 PM MST Thu Sep 9 2021

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 8 PM MST THIS
EVENING...

* WHAT...Dangerously hot conditions. Afternoon temperatures 107 
  to 110 expected. 

* WHERE...Portions of south central Arizona.

* WHEN...From 10 AM this morning to 8 PM MST this evening.

* IMPACTS...High Heat Risk. Overexposure can cause heat cramps 
  and heat exhaustion to develop and, without intervention, can 
  lead to heat stroke. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

An Excessive Heat Warning means that a period of very hot
temperatures, even by local standards, will occur. Actions should
be taken to lessen the impact of the extreme heat.

Stay indoors and seek air-conditioned buildings. Drink water,
more than usual, and avoid dehydrating alcoholic, sugary, or
caffeinated drinks. Dress for the heat - lightweight and light-
colored clothing. Eat small meals and eat more often. Monitor
those with a higher vulnerability to heat, including small
children. Check in on family, friends, and neighbors, especially
the elderly. If engaging in outdoor activity, take longer and
more frequent breaks and avoid the hottest parts of the day.
Never leave kids or pets unattended in cars.

Public cooling shelters are available in some areas. Consult
county officials for more details, which may include guidance for
proper social distancing measures.

Recognize the signs and symptoms of heat-related illness. Early
signs include thirst and muscle cramps. Heat exhaustion may
include: cool, moist, pale skin; headache; dizziness; weakness or
exhaustion; nausea. The most serious illness is heat stroke,
which may include: vomiting; confusion; throbbing headache;
decreased alertness or loss of consciousness; high body
temperature (above 105F); hot, dry skin; rapid, weak pulse;
rapid, shallow breathing; seizures.

Heat stroke can be DEADLY. Treat as an emergency and call 9 1 1.

Continue to monitor NWS forecasts, broadcast outlets, and local
government for updates.

&&

$$
465 
WWUS75 KPSR 100257
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
757 PM MST Thu Sep 9 2021

CAZ561-570-100400-
/O.EXP.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Joshua Tree NP East-Chuckwalla Valley-
Including the city of Midland
757 PM PDT Thu Sep 9 2021

...EXCESSIVE HEAT WARNING WILL EXPIRE AT 8 PM PDT THIS EVENING...

$$

AZZ530-533-538-CAZ569-100400-
/O.EXP.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Parker Valley-Central La Paz-Tonopah Desert-Palo Verde Valley-
Including the cities of Parker, Ehrenberg, Brenda, Harcuvar, 
Quartzsite, Vicksburg, Vicksburg Junction, Salome, Arlington, 
Hassayampa, Tonopah, Wintersburg, Blythe, Palo Verde, and Ripley
757 PM MST Thu Sep 9 2021 /757 PM PDT Thu Sep 9 2021/

...EXCESSIVE HEAT WARNING WILL EXPIRE AT 8 PM MST /8 PM PDT/ THIS
EVENING...

$$

AZZ537-540>544-546-548>551-100400-
/O.EXP.KPSR.EH.W.0007.000000T0000Z-210910T0300Z/
Northwest Valley-Buckeye/Avondale-Cave Creek/New River-
Deer Valley-Central Phoenix-North Phoenix/Glendale-
Scottsdale/Paradise Valley-East Valley-Fountain Hills/East Mesa-
South Mountain/Ahwatukee-Southeast Valley/Queen Creek-
Including the cities of Circle City, Surprise, Wittmann, 
Beardsley, Sun City West, Avondale, Cashion, Goodyear, Liberty, 
Scottsdale, Peoria, Phoenix, Paradise Valley, Mesa, Chandler, 
Tempe, Gilbert, Fountain Hills, Sun Lakes, and Queen Creek
757 PM MST Thu Sep 9 2021

...EXCESSIVE HEAT WARNING WILL EXPIRE AT 8 PM MST THIS EVENING...

$$

What forecasters said that day

The local office's own words before this excessive heat warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Phoenix, AZ wrote its last area forecast discussion before this excessive heat warning went out at Sep 6, 10:33 AM MST, 1 hour 39 minutes earlier.

Area forecast discussion, Sep 6, 10:33 AM MST, 1 hour 39 minutes before
Area Forecast Discussion
National Weather Service Phoenix AZ
1033 AM MST Mon Sep 6 2021

.UPDATE...
Updated 18Z aviation discussion.

&&

.SYNOPSIS...
Strong high pressure aloft will be the dominant weather feature
across the Southwestern U.S. this week providing above normal
temperatures for much of the region. Generally dry conditions
will also prevail despite somewhat higher humidity levels, though
slight chances for storms may become possible later this week
across southeast California and the Arizona high country. Daily
high temperatures will mostly range from 105 to 108 degrees across
the Arizona lower deserts to a couple degrees warmer across
southeast California and southwest Arizona.

&&

.DISCUSSION...
An anomalously strong upper level high pressure ridge currently
centered over central California into western Nevada will continue
to be the dominant weather feature across our region this week as
it slowly drifts eastward. Upper level heights throughout the
Great Basin, into much of California and northwestern Arizona are
forecast to be near record climo for the first half of this week.
500mb heights for southern Arizona and southern California will be
a bit lower, but still mostly in a 592-595dm range and nearing 99%
of climo.

For today, the morning hours will feel a bit sticky due to a
strong Gulf of California moisture surge and dew points back into
the 60s and even 70s closer to Yuma. However, because of the
increased boundary layer moisture, high temperatures today will
likely fall back to near normal. These briefly lower high
temperatures will likely end by Tuesday or at the latest Wednesday
as we gradually lose some of the moisture and forecast highs creep
back upward, possibly reaching 110 degrees across the western
deserts. Strong subsidence aloft will keep a lid on convection
through Tuesday with only very minimal chances (5-10%) for an
isolated storm across eastern Gila County.

The main forecast concern for this week will be the potential for
localized areas of High HeatRisk, particularly during the latter
half of the week when the NBM deterministic forecast highs reach
into a 105-107 degree range for the Arizona lower deserts to as
high as 110 degrees across southeast California. However, looking
at the NBM 75th percentile boosts highs to around 109 degrees for
Phoenix later this week to 110-112 degrees in southeast
California. Boundary layer moisture and what the daytime surface
dew points end up being will likely determine how warm high
temperatures will get this week. Starting Wednesday, the NBM shows
daily probabilities any where from 10-20% of tying record highs
in Phoenix. Model ensembles have definitely shifted more toward
the upper level ridge being dominant this week and almost
certainly keeping any significant tropical moisture south and west
of our area. There may a slight chance of some isolated storms
later this week across the western deserts and the Arizona high
country, but NBM PoPs are mostly below 15%. Even lower chances are
expected across the south-central Arizona deserts into eastern
Arizona where very limited moisture and stronger subsidence is
likely to be in place. Later this week, the high pressure ridge is
expected to stall out somewhere across the eastern portion of our
region, likely keeping our weather mostly dry and hot through the
upcoming weekend.

&&

.AVIATION...Updated at 1733Z

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT;
Southeast California/Southwest Arizona including KIPL and KBLH:

No major aviation impacts are expected through the TAF period as
clear skies and relatively light winds prevail. Light southerly
crosswinds at the Phoenix terminals will veer to westerly at 5-10
knots this afternoon between 20-21Z, but confidence on the exact
timing is currently low. A Gulf surge will reinforce westerly flow
this evening into the overnight hours across the entire region,
possibly causing 15-20 knot gusts for a few hours. Westerly winds to
prevail all night/through Tuesday morning at all terminals, except
for light southeasterly for a brief period at KIWA early Tuesday.
Unlike yesterday, outflows from storms in SE Arizona have less than
a 10% chance of impacting the Phoenix metro. Winds will persist out
of the southeast at KIPL and south at KBLH at around 10 knots
through the TAF period, with only brief gusts above 15 knots this
afternoon.

&&

.FIRE WEATHER...
Wednesday through Sunday:
Strong high pressure will dominate over the Great Basin into the
Desert Southwest late this week into the weekend providing
generally dry conditions and above normal temperatures. Chances
for showers and thunderstorms will be very limited through the
period, especially over the Arizona lower deserts where chances
will be less than 5%. High temperatures are likely to run a few
degrees above normal throughout the period with some lower desert
areas potentially seeing a return of 110 degree readings. Min RH
levels will mostly range from 15-25% through the forecast period,
while max RHs generally range from 40-60% (locally higher). Apart
from thunderstorms, strong wind events are not anticipated.

&&

.SPOTTER INFORMATION STATEMENT...
Spotters should follow standard reporting procedures.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

DISCUSSION...Kuhlman
AVIATION...Percha/Hopper
FIRE WEATHER...Kuhlman

The office that day

Everything else NWS Phoenix, AZ issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 5, 5:04 PM MSTSevere Thunderstorm WarningPSRGila, Pinal41 min
Sep 5, 5:36 PM MSTFlash Flood Warning Considerable damage threatPSRGila4 hr
Sep 5, 5:43 PM MSTDust Storm AdvisoryPSRMaricopa, Pinal89 min

Nearby

Excessive Heat Warnings in California, 2021Excessive Heat Warnings in Arizona, 2021Every excessive heat warning in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.