High Wind Warning 2, NWS Phoenix, AZ

280 
WWUS75 KPSR 212053
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
153 PM MST Mon Feb 21 2022

CAZ562-221200-
/O.CAN.KPSR.WI.Y.0007.000000T0000Z-220221T2100Z/
/O.EXT.KPSR.HW.W.0002.220221T2053Z-220222T0800Z/
/O.CON.KPSR.DU.Y.0005.000000T0000Z-220222T0300Z/
/O.CON.KPSR.WI.Y.0008.220222T0800Z-220223T1200Z/
Imperial County Southwest-
1253 PM PST Mon Feb 21 2022

...HIGH WIND WARNING NOW IN EFFECT UNTIL MIDNIGHT PST TONIGHT...
...BLOWING DUST ADVISORY REMAINS IN EFFECT UNTIL 7 PM PST THIS
EVENING...
...WIND ADVISORY REMAINS IN EFFECT FROM MIDNIGHT TONIGHT TO 4 AM
PST WEDNESDAY...

* WHAT...For the High Wind Warning, southwest winds 30 to 40 mph
  with gusts up to 65 mph. For the Blowing Dust Advisory,
  visibility under one mile. For the Wind Advisory, southwest
  winds 25 to 35 mph with gusts up to 55 mph. 

* WHERE...Southwest corner of Imperial County.

* WHEN...For the High Wind Warning, until midnight PST tonight. 
  For the Blowing Dust Advisory, until 7 PM PST this evening. 
  For the Wind Advisory, from midnight tonight to 4 AM PST 
  Wednesday.

* IMPACTS...Hazardous driving conditions due to reduced
  visibility. Very difficult driving conditions, especially for
  larger vehicles traveling along roads with crosswinds. Light,
  unsecured objects will become airborne. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be ready for a sudden drop in visibility. If you encounter
blowing dust or blowing sand on the roadway or see it
approaching, pull off the road as far as possible and put your
vehicle in park. Turn the lights all the way off and keep your
foot off the brake pedal.

Remember, pull aside, stay alive.

A High Wind Warning means a hazardous high wind event is expected
or occurring. Sustained wind speeds of at least 40 mph or gusts
of 58 mph or more can lead to property damage. In addition,
strong winds over desert areas could result in briefly lowered
visibilities to well under a mile at times in blowing dust or
blowing sand. Use extra caution.

&&

$$

CAZ563-566-567-221200-
/O.EXB.KPSR.WI.Y.0008.220222T1800Z-220223T0300Z/
/O.CON.KPSR.DU.Y.0005.000000T0000Z-220222T0300Z/
/O.CON.KPSR.WI.Y.0007.000000T0000Z-220222T0500Z/
Salton Sea-Imperial County West-Imperial Valley-
Including the cities of Desert Shores, Coolidge Springs, 
Salton City, Winona, Coyote Wells, Ocotillo, Plaster City, 
El Centro, Calexico, Alamorio, and Brawley
1253 PM PST Mon Feb 21 2022

...BLOWING DUST ADVISORY REMAINS IN EFFECT UNTIL 7 PM PST THIS
EVENING...
...WIND ADVISORY REMAINS IN EFFECT UNTIL 9 PM PST THIS EVENING...
...WIND ADVISORY IN EFFECT FROM 10 AM TO 7 PM PST TUESDAY...

* WHAT...For the Blowing Dust Advisory, visibility under one mile.
  For the first Wind Advisory, west winds 20 to 30 mph with gusts
  up to 45 mph.

* WHERE...Salton Sea, Western Imperial County and Imperial 
  Valley.

* WHEN...For the Blowing Dust Advisory, until 7 PM PST this 
  evening. For the first Wind Advisory, until 9 PM PST this 
  evening. For the second Wind Advisory, from 10 AM to 7 PM PST 
  Tuesday.

* IMPACTS...Hazardous driving conditions due to reduced
  visibility. Very difficult driving conditions, especially for
  larger vehicles traveling along roads with crosswinds. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be ready for a sudden drop in visibility. If you encounter
blowing dust or blowing sand on the roadway or see it
approaching, pull off the road as far as possible and put your
vehicle in park. Turn the lights all the way off and keep your
foot off the brake pedal.

Remember, pull aside, stay alive.

A Wind Advisory means that sustained wind speeds of between
30 and 40 mph are expected, or wind gusts of between 40 and
58 mph. Winds this strong can make driving difficult, especially
for high profile vehicles. In addition, strong winds over desert
areas could result in briefly lowered visibilities to well under
a mile at times in blowing dust or blowing sand. Use extra
caution.

&&

$$

CAZ564-565-220500-
/O.CON.KPSR.DU.Y.0005.000000T0000Z-220222T0300Z/
/O.CON.KPSR.WI.Y.0007.000000T0000Z-220222T0500Z/
Chuckwalla Mountains-Imperial County Southeast-
Including the city of Imperial Hot Mineral Springs
1253 PM PST Mon Feb 21 2022

...BLOWING DUST ADVISORY REMAINS IN EFFECT UNTIL 7 PM PST THIS
EVENING...
...WIND ADVISORY REMAINS IN EFFECT UNTIL 9 PM PST THIS EVENING...

* WHAT...For the Blowing Dust Advisory, visibility under one mile.
  For the Wind Advisory, west winds 20 to 30 mph with gusts up to
  45 mph.

* WHERE...Chuckwalla Mountains and Southeastern Imperial County.

* WHEN...For the Blowing Dust Advisory, until 7 PM PST this
  evening. For the Wind Advisory, until 9 PM PST this evening.

* IMPACTS...Hazardous driving conditions due to reduced
  visibility. Difficult driving conditions, especially for larger
  vehicles traveling along roads with crosswinds. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be ready for a sudden drop in visibility. If you encounter
blowing dust or blowing sand on the roadway or see it
approaching, pull off the road as far as possible and put your
vehicle in park. Turn the lights all the way off and keep your
foot off the brake pedal.

Remember, pull aside, stay alive.

A Wind Advisory means that sustained wind speeds of between
30 and 40 mph are expected, or wind gusts of between 40 and
58 mph. Winds this strong can make driving difficult, especially
for high profile vehicles. In addition, strong winds over desert
areas could result in briefly lowered visibilities to well under
a mile at times in blowing dust or blowing sand. Use extra
caution.

&&

$$

237 
WWUS75 KPSR 220300
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
800 PM MST Mon Feb 21 2022

CAZ562-221200-
/O.EXP.KPSR.DU.Y.0005.000000T0000Z-220222T0300Z/
/O.CON.KPSR.HW.W.0002.000000T0000Z-220222T0800Z/
/O.CON.KPSR.WI.Y.0008.220222T0800Z-220223T1200Z/
Imperial County Southwest-
700 PM PST Mon Feb 21 2022


...BLOWING DUST ADVISORY WILL EXPIRE AT 7 PM PST THIS EVENING...
...HIGH WIND WARNING REMAINS IN EFFECT UNTIL MIDNIGHT PST
TONIGHT...
...WIND ADVISORY REMAINS IN EFFECT FROM MIDNIGHT TONIGHT TO 4 AM
PST WEDNESDAY...

* WHAT...For the High Wind Warning, southwest winds 25 to 35 mph 
  with gusts up to 60 mph. For the Wind Advisory, west winds 20 
  to 30 mph with gusts up to 65 mph expected.

* WHERE...Southwest corner of Imperial County.

* WHEN...For the High Wind Warning, until midnight PST tonight. 
  For the Blowing Dust Advisory, until 7 PM PST this evening. 
  For the Wind Advisory, from midnight tonight to 4 AM PST 
  Wednesday.

* IMPACTS...Very difficult driving conditions, especially for 
  larger vehicles traveling along roads with crosswinds. Light, 
  unsecured objects will become airborne. Moderate tree and 
  minor structural damage possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A High Wind Warning means a hazardous high wind event is expected
or occurring. Sustained wind speeds of at least 40 mph or gusts
of 58 mph or more can lead to property damage. In addition,
strong winds over desert areas could result in briefly lowered
visibilities to well under a mile at times in blowing dust or
blowing sand. Use extra caution.

&&

$$

CAZ563-566-567-221200-
/O.EXP.KPSR.DU.Y.0005.000000T0000Z-220222T0300Z/
/O.CON.KPSR.WI.Y.0007.000000T0000Z-220222T0500Z/
/O.CON.KPSR.WI.Y.0008.220222T1800Z-220223T0300Z/
Salton Sea-Imperial County West-Imperial Valley-
Including the cities of Desert Shores, Coolidge Springs, 
Salton City, Winona, Coyote Wells, Ocotillo, Plaster City, 
El Centro, Calexico, Alamorio, and Brawley
700 PM PST Mon Feb 21 2022

...BLOWING DUST ADVISORY WILL EXPIRE AT 7 PM PST THIS EVENING...
...WIND ADVISORY REMAINS IN EFFECT UNTIL 9 PM PST THIS EVENING...
...WIND ADVISORY REMAINS IN EFFECT FROM 10 AM TO 7 PM PST
TUESDAY...


* WHAT...For the first Wind Advisory, west winds 20 to 30 mph 
  with gusts up to 50 mph. For the second Wind Advisory, west 
  winds 20 to 30 mph with gusts up to 45 mph expected.

* WHERE...Salton Sea, Western Imperial County and Imperial 
  Valley.

* WHEN...For the Blowing Dust Advisory, until 7 PM PST this 
  evening. For the first Wind Advisory, until 9 PM PST this 
  evening. For the second Wind Advisory, from 10 AM to 7 PM PST 
  Tuesday.

* IMPACTS...Difficult driving conditions, especially for larger 
  vehicles traveling along roads with crosswinds. Light, 
  unsecured objects may become airborne.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Wind Advisory means that sustained wind speeds of between
30 and 40 mph are expected, or wind gusts of between 40 and
58 mph. Winds this strong can make driving difficult, especially
for high profile vehicles. In addition, strong winds over desert
areas could result in briefly lowered visibilities to well under
a mile at times in blowing dust or blowing sand. Use extra
caution.

&&

$$

CAZ564-565-220500-
/O.EXP.KPSR.DU.Y.0005.000000T0000Z-220222T0300Z/
/O.CON.KPSR.WI.Y.0007.000000T0000Z-220222T0500Z/
Chuckwalla Mountains-Imperial County Southeast-
Including the city of Imperial Hot Mineral Springs
700 PM PST Mon Feb 21 2022

...WIND ADVISORY REMAINS IN EFFECT UNTIL 9 PM PST THIS EVENING...
...BLOWING DUST ADVISORY WILL EXPIRE AT 7 PM PST THIS EVENING...

* WHAT...West winds 20 to 30 mph with gusts up to 55 mph.

* WHERE...Chuckwalla Mountains and Southeastern Imperial County.

* WHEN...For the Blowing Dust Advisory, until 7 PM PST this 
  evening. For the Wind Advisory, until 9 PM PST this evening.

* IMPACTS...Difficult driving conditions, especially for larger 
  vehicles traveling along roads with crosswinds. Light, 
  unsecured objects may become airborne. Minor tree damage 
  possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Wind Advisory means that sustained wind speeds of between
30 and 40 mph are expected, or wind gusts of between 40 and
58 mph. Winds this strong can make driving difficult, especially
for high profile vehicles. In addition, strong winds over desert
areas could result in briefly lowered visibilities to well under
a mile at times in blowing dust or blowing sand. Use extra
caution.

&&

$$

859 
WWUS75 KPSR 220447
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
947 PM MST Mon Feb 21 2022

CAZ563-566-567-221200-
/O.EXP.KPSR.WI.Y.0007.000000T0000Z-220222T0500Z/
/O.CON.KPSR.WI.Y.0008.220222T1800Z-220223T0300Z/
Salton Sea-Imperial County West-Imperial Valley-
Including the cities of Desert Shores, Coolidge Springs, 
Salton City, Winona, Coyote Wells, Ocotillo, Plaster City, 
El Centro, Calexico, Alamorio, and Brawley
847 PM PST Mon Feb 21 2022

...WIND ADVISORY WILL EXPIRE AT 9 PM PST THIS EVENING...
...WIND ADVISORY REMAINS IN EFFECT FROM 10 AM TO 7 PM PST
TUESDAY...


* WHAT...For the first Wind Advisory, west winds 20 to 30 mph 
  with gusts up to 50 mph. For the second Wind Advisory, west 
  winds 20 to 30 mph with gusts up to 45 mph expected. 

* WHERE...Salton Sea, Western Imperial County and Imperial 
  Valley. 

* WHEN...For the Blowing Dust Advisory, until 7 PM PST this 
  evening. For the first Wind Advisory, until 9 PM PST this 
  evening. For the second Wind Advisory, from 10 AM to 7 PM PST 
  Tuesday. 

* IMPACTS...Difficult driving conditions, especially for larger 
  vehicles traveling along roads with crosswinds. Light, 
  unsecured objects may become airborne. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Wind Advisory means that sustained wind speeds of between
30 and 40 mph are expected, or wind gusts of between 40 and
58 mph. Winds this strong can make driving difficult, especially
for high profile vehicles. In addition, strong winds over desert
areas could result in briefly lowered visibilities to well under
a mile at times in blowing dust or blowing sand. Use extra
caution.

&&

$$

CAZ564-565-220600-
/O.EXP.KPSR.WI.Y.0007.000000T0000Z-220222T0500Z/
Chuckwalla Mountains-Imperial County Southeast-
Including the cities of Imperial Hot Mineral Springs and
Winterhaven
847 PM PST Mon Feb 21 2022

...WIND ADVISORY WILL EXPIRE AT 9 PM PST THIS EVENING...

Wind gusts have fallen to below advisory criteria. However, breezy
to very breezy wind conditions will continue to affect the area
tonight. 

$$

CAZ562-221200-
/O.CON.KPSR.HW.W.0002.000000T0000Z-220222T0800Z/
/O.CON.KPSR.WI.Y.0008.220222T0800Z-220223T1200Z/
Imperial County Southwest-
Including the city of Mountain Spring
847 PM PST Mon Feb 21 2022

...HIGH WIND WARNING REMAINS IN EFFECT UNTIL MIDNIGHT PST
TONIGHT...
...WIND ADVISORY REMAINS IN EFFECT FROM MIDNIGHT TONIGHT TO 4 AM
PST WEDNESDAY...

* WHAT...For the High Wind Warning, southwest winds 25 to 35 mph 
  with gusts up to 60 mph. For the Wind Advisory, west winds 20 
  to 30 mph with gusts up to 65 mph expected. 

* WHERE...Southwest corner of Imperial County.

* WHEN...For the High Wind Warning, until midnight PST tonight. 
  For the Blowing Dust Advisory, until 7 PM PST this evening. 
  For the Wind Advisory, from midnight tonight to 4 AM PST 
  Wednesday. 

* IMPACTS...Very difficult driving conditions, especially for 
  larger vehicles traveling along roads with crosswinds. Light, 
  unsecured objects will become airborne. Moderate tree and 
  minor structural damage possible. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A High Wind Warning means a hazardous high wind event is expected
or occurring. Sustained wind speeds of at least 40 mph or gusts
of 58 mph or more can lead to property damage. In addition,
strong winds over desert areas could result in briefly lowered
visibilities to well under a mile at times in blowing dust or
blowing sand. Use extra caution.

&&

$$

356 
WWUS75 KPSR 220817
NPWPSR

URGENT - WEATHER MESSAGE
National Weather Service Phoenix AZ
117 AM MST Tue Feb 22 2022

CAZ562-222030-
/O.EXP.KPSR.HW.W.0002.000000T0000Z-220222T0800Z/
/O.NEW.KPSR.DU.Y.0006.220222T1700Z-220223T0300Z/
/O.CON.KPSR.WI.Y.0008.000000T0000Z-220223T1200Z/
Imperial County Southwest-
1217 AM PST Tue Feb 22 2022

...WIND ADVISORY REMAINS IN EFFECT UNTIL 4 AM PST WEDNESDAY...
...BLOWING DUST ADVISORY IN EFFECT FROM 9 AM THIS MORNING TO 7 PM
PST THIS EVENING...

* WHAT...For the Blowing Dust Advisory, visibility between one 
  quarter mile and one mile in blowing dust expected. For the 
  Wind Advisory, west winds 25 to 35 mph with gusts up to 60 mph.

* WHERE...Southwest corner of Imperial County.

* WHEN...For the Blowing Dust Advisory, from 9 AM this morning 
  to 7 PM PST this evening. For the Wind Advisory, until 4 AM 
  PST Wednesday.

* IMPACTS...Hazardous driving conditions due to reduced 
  visibility. Difficult driving conditions, especially for 
  larger vehicles traveling along roads with crosswinds. Light, 
  unsecured objects may become airborne. Minor tree damage 
  possible.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be ready for a sudden drop in visibility. If you encounter
blowing dust or blowing sand on the roadway or see it
approaching, pull off the road as far as possible and put your
vehicle in park. Turn the lights all the way off and keep your
foot off the brake pedal.

Remember, pull aside, stay alive.

A Wind Advisory means that sustained wind speeds of between
30 and 40 mph are expected, or wind gusts of between 40 and
58 mph. Winds this strong can make driving difficult, especially
for high profile vehicles. In addition, strong winds over desert
areas could result in briefly lowered visibilities to well under
a mile at times in blowing dust or blowing sand. Use extra
caution.

&&

$$

CAZ563-566-567-222030-
/O.NEW.KPSR.DU.Y.0006.220222T1700Z-220223T0300Z/
/O.EXT.KPSR.WI.Y.0008.220222T1700Z-220223T0500Z/
Salton Sea-Imperial County West-Imperial Valley-
Including the cities of Desert Shores, Coolidge Springs, 
Salton City, Winona, Coyote Wells, Ocotillo, Plaster City, 
El Centro, Calexico, Alamorio, and Brawley
1217 AM PST Tue Feb 22 2022

...BLOWING DUST ADVISORY IN EFFECT FROM 9 AM THIS MORNING TO 7 PM
PST THIS EVENING...
...WIND ADVISORY NOW IN EFFECT FROM 9 AM THIS MORNING TO 9 PM PST
THIS EVENING...

* WHAT...For the Blowing Dust Advisory, visibility between one 
  quarter mile and one mile in blowing dust expected. For the 
  Wind Advisory, west winds 15 to 25 mph with gusts up to 40 mph 
  expected.

* WHERE...Salton Sea, Western Imperial County and Imperial 
  Valley.

* WHEN...For the Blowing Dust Advisory, from 9 AM this morning 
  to 7 PM PST this evening. For the Wind Advisory, from 9 AM 
  this morning to 9 PM PST this evening.

* IMPACTS...Hazardous driving conditions due to reduced 
  visibility. Difficult driving conditions, especially for 
  larger vehicles traveling along roads with crosswinds. Light, 
  unsecured objects may become airborne.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be ready for a sudden drop in visibility. If you encounter
blowing dust or blowing sand on the roadway or see it
approaching, pull off the road as far as possible and put your
vehicle in park. Turn the lights all the way off and keep your
foot off the brake pedal.

Remember, pull aside, stay alive.

A Wind Advisory means that sustained wind speeds of between
30 and 40 mph are expected, or wind gusts of between 40 and
58 mph. Winds this strong can make driving difficult, especially
for high profile vehicles. In addition, strong winds over desert
areas could result in briefly lowered visibilities to well under
a mile at times in blowing dust or blowing sand. Use extra
caution.

&&

$$

AZZ530-CAZ560-561-564-565-568>570-222030-
/O.NEW.KPSR.DU.Y.0006.220222T1700Z-220223T0300Z/
/O.EXB.KPSR.WI.Y.0008.220222T1700Z-220223T0500Z/
Parker Valley-Joshua Tree NP West-Joshua Tree NP East-
Chuckwalla Mountains-Imperial County Southeast-Chiriaco Summit-
Palo Verde Valley-Chuckwalla Valley-
Including the cities of Parker, Ehrenberg, Cottonwood Visitor, 
Lost Horse-Keys Village, Imperial Hot Mineral Springs, 
Chiriaco Summit, Blythe, Palo Verde, Ripley, and Midland
117 AM MST Tue Feb 22 2022 /1217 AM PST Tue Feb 22 2022/

...BLOWING DUST ADVISORY IN EFFECT FROM 10 AM MST /9 AM PST/ THIS
MORNING TO 8 PM MST /7 PM PST/ THIS EVENING...
...WIND ADVISORY IN EFFECT FROM 10 AM MST /9 AM PST/ THIS MORNING
TO 10 PM MST /9 PM PST/ THIS EVENING...

* WHAT...For the Blowing Dust Advisory, visibility between one 
  quarter mile and one mile in blowing dust expected. For the 
  Wind Advisory, southwest winds 20 to 30 mph with gusts up to 
  45 mph expected.

* WHERE...In Arizona, Parker Valley. In California, Joshua
  National Tree Park, Chuckwalla Mountains, Southeastern Imperial
  County, Chiriaco Summit, Palo Verde Valley and Chuckwalla 
  Valley.

* WHEN...For the Blowing Dust Advisory, from 10 AM MST /9 AM 
  PST/ this morning to 8 PM MST /7 PM PST/ this evening. For the 
  Wind Advisory, from 10 AM MST /9 AM PST/ this morning to 10 PM 
  MST /9 PM PST/ this evening.

* IMPACTS...Hazardous driving conditions due to reduced 
  visibility. Difficult driving conditions, especially for 
  larger vehicles traveling along roads with crosswinds. Light, 
  unsecured objects may become airborne.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be ready for a sudden drop in visibility. If you encounter
blowing dust or blowing sand on the roadway or see it
approaching, pull off the road as far as possible and put your
vehicle in park. Turn the lights all the way off and keep your
foot off the brake pedal.

Remember, pull aside, stay alive.

A Wind Advisory means that sustained wind speeds of between
30 and 40 mph are expected, or wind gusts of between 40 and
58 mph. Winds this strong can make driving difficult, especially
for high profile vehicles. In addition, strong winds over desert
areas could result in briefly lowered visibilities to well under
a mile at times in blowing dust or blowing sand. Use extra
caution.

&&

$$

Area Forecast Discussion
National Weather Service Phoenix AZ
1033 PM MST Sun Feb 20 2022

.UPDATE...6z Aviation Discussion...

&&

.SYNOPSIS...
A series of weather disturbances moving across the region through
the middle of the week will produce unsettled weather in the form of
locally gusty winds, scattered lower elevation rain showers,
mountain snowfall, and much cooler temperatures. While stronger
winds will precede the main system, the bulk of the impacts will be
experienced on Wednesday. More tranquil weather with moderating
temperatures will be common during the latter half of the week.

&&

.DISCUSSION...
The larger Conus flow pattern will temporarily realign during the
first half the week as progressive longwave features briefly allow
deep, high amplitude troughing to carve into the Southwest while
broad subtropical ridging becomes established over the SE Conus.
This configuration will provide a period of unsettled weather across
the forecast area during the first part of the week, however will
not persist as high amplitude western North American ridging and
some form of an omega block quickly becomes reestablished by the end
of the week.

The fingerprints of this upcoming pattern change can be seen in
afternoon WV imagery as a weak cutoff low west of the Baja was
filling and becoming absorbed into the downstream flow as a result
of a pronounced upstream kicker wave digging through the Pacific NW.
By tonight, the former feature will become sheared into the strong
jet flow losing definition while the latter wave carves out the mean
trough position over the Great Basin. While height falls will be
rather modest as the main bulk of the shortwave passes through far
northern AZ, tightly packed ensemble output provide good confidence
temperatures will retreat back to normal levels Monday.

The increasing pressure and thermal gradient in the basal portion of
the trough will create a strengthening u-wind component in the H8-H7
layer cresting mountainous areas of SE California Monday afternoon.
Close investigation of vertical motion fields, theta-e/humidity
levels, and low level momentum transfer suggests enhanced winds
descending the leeward side of the San Diego mountains. An enhanced
onshore flow and depth of the marine layer on the windward side of
the mountains coincident with fropa Monday afternoon should promote
mountain waves and hydraulic jumps more removed from the actual
terrain features for a period into Monday evening. Have expanded the
wind advisory eastward for a short period based on HREF output,
forecast BUFR sounding profiles, and historical precedent. Travel
difficulty for high profile vehicles and blowing dust streamers
adjacent to desert areas recently disturbed will be the primary
hazards.

While the initial shortwave will eject into the central high plains
Tuesday, broad cyclonic flow will linger over the CWA awaiting the
larger upstream PV anomaly and cold core. Models indicate a shallow
corridor of moisture/saturation in the H8-H7 layer over south-
central AZ which may conceivably be lifted via modest isentropic
and orographically enhanced ascent, however limited dynamics along
with a capping warm layer aloft may substantially hinder
precipitation processes. Similar to Monday, strong gusty winds over
parts of the SE CA will likely be the greatest impact though with
shortwave features more removed from the CWA and heights falls
nearly absent, winds should not be as intense or expansive.
Nevertheless, required NBM forecast winds still appear somewhat low
given the pattern alignment.

The main trough will finally arrive into the region Wednesday with
an intense negative height anomaly tapping an excellent reservoir of
PV from the northern latitudes creating a favorably dynamic system.
NAEFS output continues to show midtropospheric height/thermal
anomalies 2-3 normalized standard deviations below normal, or in the
lowest 2% of outcomes based on mid/late February climatology.
Dynamical/frontogentical forcing will be maximized during the
daylight hours Wednesday as a pronounced cold core (H5 below -30C)
and tropopause bowl descend into the forecast area.

While one limiting factor with this system will be moisture
availability with mixing ratios not exceeded 5 g/kg (and total
column PWATs hovering around 1/2 inch), the strong dynamic ascent
should compensate for this deficiency. Another factor limiting
accumulations will be residence time of the forcing and moisture
collocation of the front and negative PV anomaly. All told,
ensembles are in good agreement that the western CWA will receive
minimal (if any) accumulations with strong clustering below 0.05",
locations around Phoenix filling over 75% of members in a 0.10-0.25"
range, and closer to a 0.50-0.75" range in foothill and higher
terrain areas north and east of Phoenix. However, there are a few
more subtle factors that may affect the outcome for many locations
that go beyond the official provided forecast.

Given the depth, intensity, orientation and timing of the system,
some deterministic output indicates weak instability (50-100 K/kg
MUCape) materializing along the front and leading edge of the cold
core aloft acting to steepen lapse rates through the sfc-H7 layer.
Combined with the frontogenetical forcing, shallow topped convective
appears very plausible (if not better than a 50% chance) through
south-central AZ. Add these convective elements and steepening low
level lapse rates to plummeting freezing levels, and it certainly
would not be out of the question if numerous accounts of graupel are
witnessed prior to frontal passage of dry air advection late
Wednesday.

Another potential conundrum lies with snow potential and the
character of freezing levels and moisture profiles in the face of
strong dynamic ascent and convection. Very low confidence exists
with respect to locations and amounts of potential snowfall given
two very important aspects of this storm system. First, both prior
to the arrival of the front/PV anomaly as well as well behind the
front and within the tropopause descent, very dry air is forecast
within the -12C to -20C dendritic growth layer. This scenario would
significantly limit dendrite production and snowfall over higher
terrain areas on either end of the event versus the rudimentary NBM
calculation. Another huge issue is freezing/snow levels where
forecast BUFR soundings indicate snow levels at least 500ft below
the mandated NBM and official forecast output. This has been a
historical bias in NBM during strongly forced events; and adding in
the convective potential, snow levels may end up closer 1000 ft
below the current forecast producing at least a rain/snow mix into
the foothills north of Phoenix in a 2500-3000ft level. Conceptually,
one would expect a temporary sweet spot in time and space along the
front where snowfall amounts would be maximized, but possibly not in
the time and space highlighted in the forecast.

Aside from the precipitation and wind potential (and uncertainties),
the greatest forecast confidence lies with temperatures falling
close to 15F below normal Wednesday and Thursday. In fact, many lower
desert locations may struggle to reach 60F which is not entirely
unusual for this time of year (normal last day of the cool season in
Phoenix not to reach 60F is Feb 26th). Morning lows Thursday and
Friday should fall near or below freezing in many of the typical
sheltered and rural communities. While this is getting a bit late in
the cold season for freezing temperatures, base50GDD accumulations
are still somewhat marginal for heightened growth yet this year
after the phenological chilling phase.

Towards the tail end of the week, WPC clusters are in good agreement
that the trough responsible for the unsettled weather will propagate
east and some form of an omega block will become established over
the Eat Pacific and western Conus. Whether the forecast area ends up
under the ridge axis or near one of the attendant vorticity centers
of the block remain to be seen, however temperatures should warm
gradually into the weekend with good confidence of dry weather
returning.

&&

.AVIATION...Updated at 0530Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
A series of disturbances approaching the region will affect our
weather slightly the next 36 hours. Diurnal tendencies continue
overnight through morning as easterlies return at metro terminals
in the next couple hours, if not already. Mid/high clouds aoa
15kft are expected during the overnight into Monday. Winds will
slowly veer from ESE to SW between 16Z and 18Z and become breezy
at times through the afternoon (15+kt gusts). Toward the end of
the TAF period Monday evening/night, guidance suggests scattered
clouds building around 5kft with winds subtly backing around out
of the S with less gustiness.

Southeast California/Southwest Arizona including KIPL and KBLH:
Light winds under 10kt continue through early morning at both
terminals (SW at BLH, W at IPL) beneath passing mid-level cloud
cover. Clearing and windy conditions are forecast Monday mid
morning through sunset. Southwesterly gusts over 30KT are forecast
at times. Trends will need to be monitored for nearby developing
lofted/blowing dust affecting VIS.

&&

.FIRE WEATHER...
Tuesday through Saturday:
A cold system will yield well below normal temperatures and locally
breezy conditions across the region during the middle of the week.
Gusts up to 30-40 mph will be possible in some areas with stronger
winds, potentially up to 40-60 mph in the more preferred terrain
gaps and ridge top locations over the western districts. The best
chances for wetting rains will exist Wednesday and focused over
eastern districts with a potential for light accumulating snow at
higher elevations such as Joshua Tree NP and southern Gila county
(generally above 3000 ft). Minimum humidity levels around 25-35%
will increase to a 40-60% range in eastern districts with the
weather system passage, then retreat back to a 10-20% range over the
weekend. Overnight recovery will be highest Tuesday and Wednesday
with 65-85% maximum humidity level.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory from noon to 9 PM PST Monday for CAZ563-566-567.

     Wind Advisory from 6 AM Monday to 4 AM PST Wednesday for CAZ562.

&&

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DISCUSSION...18/Benedict
AVIATION...Heil
FIRE WEATHER...18/Benedict