Alert archive / Missouri / Heat Advisories in 2020

Heat Advisory 2, NWS St. Louis, MO

July 17, 202029 counties in Missouri; 17 counties in Illinois

NWS St. Louis, MO issued this heat advisory at Jul 17, 2020, 1:59 AM CDT for 29 counties in Missouri; 17 counties in Illinois. It took effect at Jul 18, 2020, 12:00 PM CDT. It was in force for 31 hr.

The area

The counties it named.

The facts

Issued
Jul 17, 2020, 1:59 AM CDT (06:59 UTC)
In effect from
Jul 18, 2020, 12:00 PM CDT
Expired
Jul 19, 2020, 7:00 PM CDT
In force
31 hr
Issued by
NWS St. Louis, MO
All 46 counties

Adams County, IL, Bond County, IL, Brown County, IL, Calhoun County, IL, Clinton County, IL, Fayette County, IL, Greene County, IL, Jersey County, IL, Macoupin County, IL, Madison County, IL, Marion County, IL, Monroe County, IL, Montgomery County, IL, Pike County, IL, Randolph County, IL, Saint Clair County, IL, Washington County, IL, Audrain County, MO, Boone County, MO, Callaway County, MO, City of Saint Louis, MO, Cole County, MO, Crawford County, MO, Franklin County, MO, Gasconade County, MO, Iron County, MO, Jefferson County, MO, Knox County, MO, Lewis County, MO, Lincoln County, MO, Madison County, MO, Marion County, MO, Moniteau County, MO, Monroe County, MO, Montgomery County, MO, Osage County, MO, Pike County, MO, Ralls County, MO, Reynolds County, MO, Saint Charles County, MO, Saint Francois County, MO, Saint Louis County, MO, Sainte Genevieve County, MO, Shelby County, MO, Warren County, MO, Washington County, MO

The radar

The St Louis radar (KLSX), 18 km from the middle of the area, began a volume at 07:00 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.

The nearest sounding before it

Lincoln, IL (KILX), launched 00:00Z, 7.0 hours before the alert went out and 241 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, Lincoln, IL at 00:00Z on 2020-07-17Temperature 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, Lincoln, IL at 00:00Z on 2020-07-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -12 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
1197 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
-12 m²/s²
0-3 km storm-relative helicity
15 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

667 
WWUS73 KLSX 170659
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service Saint Louis MO
159 AM CDT Fri Jul 17 2020

ILZ058>060-064-065-069-070-074-079-097>099-MOZ034>036-041-042-
047>052-059-060-062-072>075-084-085-099-172200-
/O.NEW.KLSX.HT.Y.0002.200718T1700Z-200720T0000Z/
Audrain MO-Bond IL-Boone MO-Calhoun IL-Callaway MO-Clinton IL-
Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-Greene IL-
Iron MO-Jersey IL-Lincoln MO-Macoupin IL-Madison MO-Marion IL-
Moniteau MO-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-
Pike IL-Pike MO-Ralls MO-Randolph IL-Reynolds MO-
Saint Francois MO-Sainte Genevieve MO-Warren MO-Washington IL-
Washington MO-
Including the cities of Bowling Green, Centralia, Chester, 
Columbia, Farmington, Fulton, Jefferson City, Litchfield, Mexico,
Pittsfield, Salem, Sparta, Sullivan, Union, Vandalia, 
and Washington
159 AM CDT Fri Jul 17 2020

...HEAT ADVISORY IN EFFECT FROM NOON SATURDAY TO 7 PM CDT
SUNDAY...

* WHAT...Heat index values of 105 to 110 expected.

* WHERE...Portions of central, east central, northeast and 
  southeast Missouri and south central, southwest and west 
  central Illinois.

* WHEN...Afternoon and early evening hours on Saturday and Sunday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ095-096-MOZ018-019-026-027-172200-
/O.NEW.KLSX.HT.Y.0002.200718T1700Z-200719T0100Z/
Adams IL-Brown IL-Knox MO-Lewis MO-Marion MO-Shelby MO-
Including the cities of Hannibal, Mount Sterling, and Quincy
159 AM CDT Fri Jul 17 2020

...HEAT ADVISORY IN EFFECT FROM NOON TO 8 PM CDT SATURDAY...

* WHAT...Heat index values of 105 expected.

* WHERE...In Missouri, Knox MO, Lewis MO, Shelby MO and Marion 
  MO Counties. In Illinois, Adams IL and Brown IL Counties.

* WHEN...From noon to 8 PM CDT Saturday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ100>102-MOZ061-063>065-172200-
/O.NEW.KLSX.HT.Y.0002.200718T1700Z-200720T0000Z/
Jefferson MO-Madison IL-Monroe IL-Saint Charles MO-Saint Clair IL-
Saint Louis City MO-Saint Louis MO-
Including the cities of Alton, Belleville, Cahokia, Edwardsville,
Saint Charles, and Saint Louis
159 AM CDT Fri Jul 17 2020

...HEAT ADVISORY IN EFFECT FROM NOON SATURDAY TO 7 PM CDT
SUNDAY...

* WHAT...Heat index values of 105 to 110 expected.

* WHERE...The Greater St. Louis Metropolitan Area.

* WHEN...Afternoon and early evening hours on Saturday and Sunday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

People in the Saint Louis Metropolitan Area can get information 
about cooling centers or energy assistance related to the 
excessive heat by calling the United Way of Greater Saint Louis at
800-427-4626, or if calling from a land line phone dial 2-1-1. 
You can also call Cool Down Saint Louis at 314-241-7668.

&&

$$

CVKING
7 follow-up statements
089 
WWUS73 KLSX 171955
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service Saint Louis MO
255 PM CDT Fri Jul 17 2020

ILZ058>060-064-065-069-070-074-079-097>099-MOZ034>036-041-042-
047>052-059-060-062-072>075-084-085-099-180800-
/O.CON.KLSX.HT.Y.0002.200718T1700Z-200720T0000Z/
Audrain MO-Bond IL-Boone MO-Calhoun IL-Callaway MO-Clinton IL-
Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-Greene IL-
Iron MO-Jersey IL-Lincoln MO-Macoupin IL-Madison MO-Marion IL-
Moniteau MO-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-
Pike IL-Pike MO-Ralls MO-Randolph IL-Reynolds MO-
Saint Francois MO-Sainte Genevieve MO-Warren MO-Washington IL-
Washington MO-
Including the cities of Bowling Green, Centralia, Chester, 
Columbia, Farmington, Fulton, Jefferson City, Litchfield, Mexico,
Pittsfield, Salem, Sparta, Sullivan, Union, Vandalia, 
and Washington
255 PM CDT Fri Jul 17 2020

...HEAT ADVISORY REMAINS IN EFFECT FROM NOON SATURDAY TO 7 PM CDT
SUNDAY...

* WHAT...Heat index values of 105 to 110 expected.

* WHERE...Portions of central, east central, northeast and 
  southeast Missouri and south central, southwest and west 
  central Illinois.

* WHEN...Afternoon and early evening hours on Saturday and 
  Sunday.

* IMPACTS...Hot temperatures and high humidity may cause heat
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ095-096-MOZ018-019-026-027-180800-
/O.CON.KLSX.HT.Y.0002.200718T1700Z-200719T0100Z/
Adams IL-Brown IL-Knox MO-Lewis MO-Marion MO-Shelby MO-
Including the cities of Hannibal, Mount Sterling, and Quincy
255 PM CDT Fri Jul 17 2020

...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TO 8 PM CDT
SATURDAY...

* WHAT...Heat index values of 105 expected.

* WHERE...In Missouri, Knox MO, Lewis MO, Shelby MO and Marion 
  MO Counties. In Illinois, Adams IL and Brown IL Counties.

* WHEN...From noon to 8 PM CDT Saturday.

* IMPACTS...Hot temperatures and high humidity may cause heat
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ100>102-MOZ061-063>065-180800-
/O.CON.KLSX.HT.Y.0002.200718T1700Z-200720T0000Z/
Jefferson MO-Madison IL-Monroe IL-Saint Charles MO-Saint Clair IL-
Saint Louis City MO-Saint Louis MO-
Including the cities of Alton, Belleville, Cahokia, Edwardsville,
Saint Charles, and Saint Louis
255 PM CDT Fri Jul 17 2020

...HEAT ADVISORY REMAINS IN EFFECT FROM NOON SATURDAY TO 7 PM CDT
SUNDAY...

* WHAT...Heat index values of 105 to 110 expected.

* WHERE...The Greater St. Louis Metropolitan Area.

* WHEN...Afternoon and early evening hours on Saturday and 
  Sunday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

People in the Saint Louis Metropolitan Area can get information
about cooling centers or energy assistance related to the
excessive heat by calling the United Way of Greater Saint Louis
at 800-427-4626, or if calling from a land line phone dial 2-1-1.
You can also call Cool Down Saint Louis at 314-241-7668.

&&

$$

Maples
943 
WWUS73 KLSX 180738
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service Saint Louis MO
238 AM CDT Sat Jul 18 2020

ILZ058>060-064-065-069-070-074-079-097>099-MOZ034>036-041-042-
047>052-059-060-062-072>075-084-085-099-182100-
/O.CON.KLSX.HT.Y.0002.200718T1700Z-200720T0000Z/
Audrain MO-Bond IL-Boone MO-Calhoun IL-Callaway MO-Clinton IL-
Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-Greene IL-
Iron MO-Jersey IL-Lincoln MO-Macoupin IL-Madison MO-Marion IL-
Moniteau MO-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-
Pike IL-Pike MO-Ralls MO-Randolph IL-Reynolds MO-
Saint Francois MO-Sainte Genevieve MO-Warren MO-Washington IL-
Washington MO-
Including the cities of Bowling Green, Centralia, Chester, 
Columbia, Farmington, Fulton, Jefferson City, Litchfield, Mexico,
Pittsfield, Salem, Sparta, Sullivan, Union, Vandalia, 
and Washington
238 AM CDT Sat Jul 18 2020

...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 7 PM CDT
SUNDAY...

* WHAT...Heat index values of 105 to 110 expected.

* WHERE...Portions of central, east central, northeast and 
  southeast Missouri and south central, southwest and west 
  central Illinois.

* WHEN...Afternoon and early evening hours today and Sunday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ095-096-MOZ018-019-026-027-182100-
/O.CON.KLSX.HT.Y.0002.200718T1700Z-200719T0100Z/
Adams IL-Brown IL-Knox MO-Lewis MO-Marion MO-Shelby MO-
Including the cities of Hannibal, Mount Sterling, and Quincy
238 AM CDT Sat Jul 18 2020

...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 8 PM CDT
THIS EVENING...

* WHAT...Heat index values of 105 to 110 expected.

* WHERE...In Missouri, Knox MO, Lewis MO, Shelby MO and Marion 
  MO Counties. In Illinois, Adams IL and Brown IL Counties.

* WHEN...From noon to 8 PM CDT today.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ100>102-MOZ061-063>065-182100-
/O.CON.KLSX.HT.Y.0002.200718T1700Z-200720T0000Z/
Jefferson MO-Madison IL-Monroe IL-Saint Charles MO-Saint Clair IL-
Saint Louis City MO-Saint Louis MO-
Including the cities of Alton, Belleville, Cahokia, Edwardsville,
Saint Charles, and Saint Louis
238 AM CDT Sat Jul 18 2020

...HEAT ADVISORY REMAINS IN EFFECT FROM NOON TODAY TO 7 PM CDT
SUNDAY...

* WHAT...Heat index values of 105 to 110 expected.

* WHERE...The Greater St. Louis Metropolitan Area.

* WHEN...Afternoon and early evening hours today and Sunday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

People in the Saint Louis Metropolitan Area can get information
about cooling centers or energy assistance related to the
excessive heat by calling the United Way of Greater Saint Louis
at 800-427-4626, or if calling from a land line phone dial 2-1-1.
You can also call Cool Down Saint Louis at 314-241-7668.

&&

$$

CVKING
053 
WWUS73 KLSX 181935
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service Saint Louis MO
235 PM CDT Sat Jul 18 2020

ILZ058>060-064-065-069-070-074-079-097>099-MOZ034>036-041-042-
047>052-059-060-062-072>075-084-085-099-190745-
/O.CON.KLSX.HT.Y.0002.000000T0000Z-200720T0000Z/
Audrain MO-Bond IL-Boone MO-Calhoun IL-Callaway MO-Clinton IL-
Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-Greene IL-
Iron MO-Jersey IL-Lincoln MO-Macoupin IL-Madison MO-Marion IL-
Moniteau MO-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-
Pike IL-Pike MO-Ralls MO-Randolph IL-Reynolds MO-
Saint Francois MO-Sainte Genevieve MO-Warren MO-Washington IL-
Washington MO-
Including the cities of Bowling Green, Centralia, Chester, 
Columbia, Farmington, Fulton, Jefferson City, Litchfield, Mexico,
Pittsfield, Salem, Sparta, Sullivan, Union, Vandalia, 
and Washington
235 PM CDT Sat Jul 18 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT SUNDAY...

* WHAT...Heat index values of 105 to 110 expected.

* WHERE...Portions of central, east central, northeast and 
  southeast Missouri and south central, southwest and west 
  central Illinois.

* WHEN...Until 7 PM CDT Sunday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ095-096-MOZ018-019-026-027-190100-
/O.CON.KLSX.HT.Y.0002.000000T0000Z-200719T0100Z/
Adams IL-Brown IL-Knox MO-Lewis MO-Marion MO-Shelby MO-
Including the cities of Hannibal, Mount Sterling, and Quincy
235 PM CDT Sat Jul 18 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 8 PM CDT THIS EVENING...

* WHAT...Heat index values of 105 to 110 expected.

* WHERE...In Illinois, Adams IL and Brown IL Counties. In 
  Missouri, Lewis MO, Knox MO, Shelby MO and Marion MO Counties.

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

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ100>102-MOZ061-063>065-190745-
/O.CON.KLSX.HT.Y.0002.000000T0000Z-200720T0000Z/
Jefferson MO-Madison IL-Monroe IL-Saint Charles MO-Saint Clair IL-
Saint Louis City MO-Saint Louis MO-
Including the cities of Alton, Belleville, Cahokia, Edwardsville,
Saint Charles, and Saint Louis
235 PM CDT Sat Jul 18 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT SUNDAY...

* WHAT...Heat index values of 105 to 110 expected.

* WHERE...In Missouri, Saint Charles MO, Saint Louis City MO, 
  Jefferson MO and Saint Louis MO Counties. In Illinois, Saint 
  Clair IL, Monroe IL and Madison IL Counties.

* WHEN...Until 7 PM CDT Sunday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

Britt
948 
WWUS73 KLSX 190055
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service Saint Louis MO
755 PM CDT Sat Jul 18 2020

ILZ095-096-MOZ018-019-026-027-190200-
/O.EXP.KLSX.HT.Y.0002.000000T0000Z-200719T0100Z/
Adams IL-Brown IL-Knox MO-Lewis MO-Marion MO-Shelby MO-
Including the cities of Hannibal, Mount Sterling, and Quincy
755 PM CDT Sat Jul 18 2020

...HEAT ADVISORY WILL EXPIRE AT 8 PM CDT THIS EVENING...

Peak heat index values are expected to be below 100 degrees for
the next couple of days. 

$$

ILZ058>060-064-065-069-070-074-079-097>099-MOZ034>036-041-042-
047>052-059-060-062-072>075-084-085-099-191300-
/O.CON.KLSX.HT.Y.0002.000000T0000Z-200720T0000Z/
Audrain MO-Bond IL-Boone MO-Calhoun IL-Callaway MO-Clinton IL-
Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-Greene IL-
Iron MO-Jersey IL-Lincoln MO-Macoupin IL-Madison MO-Marion IL-
Moniteau MO-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-
Pike IL-Pike MO-Ralls MO-Randolph IL-Reynolds MO-
Saint Francois MO-Sainte Genevieve MO-Warren MO-Washington IL-
Washington MO-
Including the cities of Bowling Green, Centralia, Chester, 
Columbia, Farmington, Fulton, Jefferson City, Litchfield, Mexico,
Pittsfield, Salem, Sparta, Sullivan, Union, Vandalia, 
and Washington
755 PM CDT Sat Jul 18 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT SUNDAY...

* WHAT...Heat index values around 105.

* WHERE...Portions of central, east central, northeast and 
  southeast Missouri and south central, southwest and west 
  central Illinois.

* WHEN...Until 7 PM CDT Sunday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ100>102-MOZ061-063>065-191300-
/O.CON.KLSX.HT.Y.0002.000000T0000Z-200720T0000Z/
Jefferson MO-Madison IL-Monroe IL-Saint Charles MO-Saint Clair IL-
Saint Louis City MO-Saint Louis MO-
Including the cities of Alton, Belleville, Cahokia, Edwardsville,
Saint Charles, and Saint Louis
755 PM CDT Sat Jul 18 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT SUNDAY...

* WHAT...Heat index values from 105 to 110.

* WHERE...In Missouri, Saint Charles MO, Saint Louis City MO, 
  Jefferson MO and Saint Louis MO Counties. In Illinois, Saint 
  Clair IL, Monroe IL and Madison IL Counties.

* WHEN...Until 7 PM CDT Sunday.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People in the Saint Louis Metropolitan Area can get information
about cooling centers or energy assistance related to the
excessive heat by calling the United Way of Greater Saint Louis at
800-427-4626, or if calling from a land line phone dial 2-1-1. 
You can also call Cool Down Saint Louis at 314-241-7668.

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

TES
536 
WWUS73 KLSX 190805
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service Saint Louis MO
305 AM CDT Sun Jul 19 2020

ILZ058>060-064-065-069-070-074-079-097>099-MOZ034>036-041-042-
047>052-059-060-062-072>075-084-085-099-192100-
/O.CON.KLSX.HT.Y.0002.000000T0000Z-200720T0000Z/
Audrain MO-Bond IL-Boone MO-Calhoun IL-Callaway MO-Clinton IL-
Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-Greene IL-
Iron MO-Jersey IL-Lincoln MO-Macoupin IL-Madison MO-Marion IL-
Moniteau MO-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-
Pike IL-Pike MO-Ralls MO-Randolph IL-Reynolds MO-
Saint Francois MO-Sainte Genevieve MO-Warren MO-Washington IL-
Washington MO-
Including the cities of Bowling Green, Centralia, Chester, 
Columbia, Farmington, Fulton, Jefferson City, Litchfield, Mexico,
Pittsfield, Salem, Sparta, Sullivan, Union, Vandalia, 
and Washington
305 AM CDT Sun Jul 19 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT THIS EVENING...

* WHAT...Heat index values of 105 to 110.

* WHERE...Portions of central, east central, northeast and 
  southeast Missouri and south central, southwest and west 
  central Illinois.

* WHEN...This afternoon and early this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ100>102-MOZ061-063>065-192100-
/O.CON.KLSX.HT.Y.0002.000000T0000Z-200720T0000Z/
Jefferson MO-Madison IL-Monroe IL-Saint Charles MO-Saint Clair IL-
Saint Louis City MO-Saint Louis MO-
Including the cities of Alton, Belleville, Cahokia, Edwardsville,
Saint Charles, and Saint Louis
305 AM CDT Sun Jul 19 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT THIS EVENING...

* WHAT...Heat index values from 105 to 110.

* WHERE...In Missouri, Saint Charles MO, Saint Louis City MO, 
  Jefferson MO and Saint Louis MO Counties. In Illinois, Saint 
  Clair IL, Monroe IL and Madison IL Counties.

* WHEN...This afternoon and evening.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

People in the Saint Louis Metropolitan Area can get information
about cooling centers or energy assistance related to the
excessive heat by calling the United Way of Greater Saint Louis
at 800-427-4626, or if calling from a land line phone dial 2-1-1.
You can also call Cool Down Saint Louis at 314-241-7668.

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

&&

$$

CVKING
336 
WWUS73 KLSX 191924
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service Saint Louis MO
224 PM CDT Sun Jul 19 2020

ILZ058>060-064-065-069-070-074-079-097>099-MOZ034>036-041-042-
047>052-059-060-062-072>075-084-085-099-200000-
/O.CON.KLSX.HT.Y.0002.000000T0000Z-200720T0000Z/
Audrain MO-Bond IL-Boone MO-Calhoun IL-Callaway MO-Clinton IL-
Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-Greene IL-
Iron MO-Jersey IL-Lincoln MO-Macoupin IL-Madison MO-Marion IL-
Moniteau MO-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-
Pike IL-Pike MO-Ralls MO-Randolph IL-Reynolds MO-
Saint Francois MO-Sainte Genevieve MO-Warren MO-Washington IL-
Washington MO-
Including the cities of Bowling Green, Centralia, Chester, 
Columbia, Farmington, Fulton, Jefferson City, Litchfield, Mexico,
Pittsfield, Salem, Sparta, Sullivan, Union, Vandalia, 
and Washington
224 PM CDT Sun Jul 19 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT THIS EVENING...

* WHAT...Heat index values around 105 degrees.

* WHERE...Portions of central, east central, northeast and 
  southeast Missouri and south central, southwest and west 
  central Illinois.

* WHEN...Until 7 PM CDT this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

ILZ100>102-MOZ061-063>065-200000-
/O.CON.KLSX.HT.Y.0002.000000T0000Z-200720T0000Z/
Jefferson MO-Madison IL-Monroe IL-Saint Charles MO-Saint Clair IL-
Saint Louis City MO-Saint Louis MO-
Including the cities of Alton, Belleville, Cahokia, Edwardsville,
Saint Charles, and Saint Louis
224 PM CDT Sun Jul 19 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 7 PM CDT THIS EVENING...

* WHAT...Heat index values around 105 degrees.

* WHERE...In Missouri, Saint Charles MO, Saint Louis City MO, 
  Jefferson MO and Saint Louis MO Counties. In Illinois, Saint 
  Clair IL, Monroe IL and Madison IL Counties.

* WHEN...Until 7 PM CDT this evening.

* IMPACTS...Hot temperatures and high humidity may cause heat 
  illnesses to occur.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

Britt
022 
WWUS73 KLSX 200007
NPWLSX

URGENT - WEATHER MESSAGE
National Weather Service Saint Louis MO
707 PM CDT Sun Jul 19 2020

ILZ058>060-064-065-069-070-074-079-097>102-MOZ034>036-041-042-
047>052-059>065-072>075-084-085-099-200115-
/O.EXP.KLSX.HT.Y.0002.000000T0000Z-200720T0000Z/
Audrain MO-Bond IL-Boone MO-Calhoun IL-Callaway MO-Clinton IL-
Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-Greene IL-
Iron MO-Jefferson MO-Jersey IL-Lincoln MO-Macoupin IL-Madison IL-
Madison MO-Marion IL-Moniteau MO-Monroe IL-Monroe MO-
Montgomery IL-Montgomery MO-Osage MO-Pike IL-Pike MO-Ralls MO-
Randolph IL-Reynolds MO-Saint Charles MO-Saint Clair IL-
Saint Francois MO-Saint Louis City MO-Saint Louis MO-
Sainte Genevieve MO-Warren MO-Washington IL-Washington MO-
Including the cities of Alton, Belleville, Bowling Green, 
Cahokia, Centralia, Chester, Columbia, Edwardsville, Farmington, 
Fulton, Jefferson City, Litchfield, Mexico, Pittsfield, 
Saint Charles, Saint Louis, Salem, Sparta, Sullivan, Union, 
Vandalia, and Washington
707 PM CDT Sun Jul 19 2020

...HEAT ADVISORY HAS EXPIRED...

The heat advisory has been allowed to expire as temperatures 
gradually cool early this evening with heat indices now below 
105.

$$

GKS

What forecasters said that day

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

NWS St. Louis, MO wrote its last area forecast discussion before this heat advisory went out at Jul 16, 10:33 PM CDT, 3 hours 26 minutes earlier.

Area forecast discussion, Jul 16, 10:33 PM CDT, 3 hours 26 minutes before
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1033 PM CDT Thu Jul 16 2020

.SHORT TERM...  (Through Late Friday Night)
Issued at 258 PM CDT Thu Jul 16 2020

Following today's modest reprieve from hot and humid conditions will
be a return to the sultry summer air mass Friday. The certainty
revolving around Friday afternoon heat indices is only somewhat
stunted by the struggle to pinpoint details with regard to a stalled
boundary and resulting thunderstorm potential.

Issues are minor through late tonight. Surface high pressure will
gradually move east through Friday morning. Surface flow turns
southwest with increasing low to mid-level moisture behind the
departing high. Where light winds intersect with better surface
moisture (recent rainfall) over southeast Missouri and portions of
southwest Illinois, we could see a brief period of patchy fog in the
pre-dawn hours Friday morning.

There are two features to watch overnight. One is another compact
vort feature that tracks west to east along the Kansas/Oklahoma
border late today and through southern Missouri through the first
half of Friday. This will likely assist the stalled boundary in
additional thunderstorm development over southern Missouri. Hi-res
guidance continues to point to a slight northward shift in the
boundary, which become quite difuse Friday afternoon. Isolated to
perhaps scattered storms are possible over the southern sections of
the forecast area, potentially reaching as far north as St. Louis by
early afternoon. The second feature is another small vort that track
from Nebraska into southern Iowa Friday afternoon. There are some
hints that a weak area of convergence extends south of this and
results in isolated storms over central Missouri. Therefore,
maintained slight chances for isolated thundertorms at the height of
diurnal instability.

Though moisture and temperatures increase Friday, apparent
temperatures above 100 degrees look more probable from central
Missouri through southeast Missouri. Given the lingering question
with the position of the boundary and/or resulting impacts from
thunderstorms, there still isn't enough confidence to say
definitively that heat indices will achieve the one day criteria.
It's more likely that duration criteria will be met, provided lack
of thunderstorm development and persistence in Saturday-Monday
temperatures trends.

Maples

.LONG TERM...  (Saturday through Next Thursday)
Issued at 258 PM CDT Thu Jul 16 2020

Heat remains the primary concern through the weekend and potentially
into early next week. However, the struggles continue with regard to
nailing down the magnitude and locations impacted by higher heat
indices, largely due to thunderstorms potential and timing in a cold
front next week. Consequently, there are some reservations and lower
confidence in the duration of the upcoming warmth.

It continues to look as though the upper ridge will extend from the
southwest CONUS, east through the mid-Atlantic seaboard Saturday.
However, the strength of the H5 ridge is somewhat offset east of the
Mississippi Valley with surface high pressure and mid-level height
rises from west to east through the southeastern CONUS.

An upper trough begins to enter the northern plains Saturday with
several vort features ejecting east in the Upper Midwest from the
base of the trough. An increasing pressure gradient begins to
develop in the mid-levels with a strengthening jet stretching from
the central plains into the northern Great Lakes. As the upper
trough moves east through the weekend, a surface cold front begins
to sink southward.

We lie squarely in between, where a remnant vort from the central
plains continues to be relatively stagnant over a diffuse stationary
boundary. Guidance continues be quite variable in the degree of
diurnal activity along and north of the this boundary as is slowly
drift north Saturday and Sunday. As this is all occurring,
disturbances to the north provide some potential for MCS development
around the northern periphery of the upper ridge.

At this point, concerns for heat still exist with the caveat that
isolated to scattered storms could develop either day. The greatest
bust potential would stem from any southward placement in MCS
development out of the north. Therefore, there is still far too much
uncertainty for any headline call. Current forecasts in the mid to
upper 90s are between the upper 50th and 75th percentile from Friday
through Monday.

By early next week, trends are showing a southward push to the cold
front and thunderstorm potential, which should effectively end the
concern for higher heat indices. It's beginning to look a bit more
active early next week.

Maples

&&

.AVIATION...  (For the 06z TAFs through 06z Friday Night)
Issued at 1033 PM CDT Thu Jul 16 2020

VFR conditions, dry weather, and light surface winds of less than
10kts will prevail at the TAF sites through the valid period.
There is a low chance (20%) of thunderstorms Friday afternoon but
too low to mention at this time. Otherwise, look for E-SE surface
winds to gradually veer more S-SE during the valid period with the
potential for brief periods of VSBY reductions in fog mainly at
KCPS later tonight.

TES

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&

WFO LSX
Hazardous weather outlook, Jul 16, 8:27 PM CDT, 5 hours 32 minutes before
Hazardous Weather Outlook
National Weather Service Saint Louis MO
827 PM CDT Thu Jul 16 2020

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-180200-
Adams IL-Audrain MO-Bond IL-Boone MO-Brown IL-Calhoun IL-Callaway MO-
Clinton IL-Cole MO-Crawford MO-Fayette IL-Franklin MO-Gasconade MO-
Greene IL-Iron MO-Jefferson MO-Jersey IL-Knox MO-Lewis MO-Lincoln MO-
Macoupin IL-Madison IL-Madison MO-Marion IL-Marion MO-Moniteau MO-
Monroe IL-Monroe MO-Montgomery IL-Montgomery MO-Osage MO-Pike IL-
Pike MO-Ralls MO-Randolph IL-Reynolds MO-Saint Charles MO-
Saint Clair IL-Saint Francois MO-Saint Louis City MO-Saint Louis MO-
Sainte Genevieve MO-Shelby MO-Warren MO-Washington IL-Washington MO-
827 PM CDT Thu Jul 16 2020

This Hazardous Weather Outlook is for portions of eastern and
central Missouri as well as west central and southwest Illinois.

.DAY ONE...Tonight.

There is a slight chance for thunderstorms in portions of southeast
Missouri. Severe storm probabilities are low.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

A prolonged and dangerous heat wave is possible for much of the area
Friday through Monday, when heat index values each afternoon and
early evening will peak between 100 and 110 degrees. The most
oppressive conditions are expected on Saturday and Sunday.

There is a chance for thunderstorms over parts of the area each day.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated tonight.

TES

The office that day

Everything else NWS St. Louis, MO issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 17, 2:46 PM CDTAreal Flood AdvisoryLSXIron, Madison, Reynolds, Saint Francois, Washington3 hr
Jul 17, 4:06 PM CDTAreal Flood AdvisoryLSXSaint Charles, Saint Louis, City of Saint Louis3 hr
Jul 17, 5:19 PM CDTFlash Flood WarningLSXSaint Charles, Saint Louis, City of Saint Louis3 hr

Nearby

Heat Advisories in Missouri, 2020Heat Advisories in Illinois, 2020Every heat advisory in 2020

Sources

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