Winter Storm Warning 4, NWS St. Louis, MO

207 
WWUS43 KLSX 171944
WSWLSX

URGENT - WINTER WEATHER MESSAGE
National Weather Service St Louis MO
144 PM CST Mon Feb 17 2025

MOZ041-181045-
/O.CAN.KLSX.WW.Y.0005.000000T0000Z-250218T0000Z/
/O.UPG.KLSX.WS.A.0003.250218T0900Z-250219T1200Z/
/O.NEW.KLSX.WW.Y.0006.250218T0600Z-250219T1200Z/
Boone MO-
Including the cities of Columbia
144 PM CST Mon Feb 17 2025

...MONDAY AFTERNOON'S WINTER WEATHER ADVISORY IS CANCELLED...
...A NEW WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 
6 AM CST WEDNESDAY...

* WHAT...Snow expected. Total snow accumulations between 2 and 4 
  inches.

* WHERE...Boone MO County.

* WHEN...From midnight tonight to 6 AM CST Wednesday.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the Monday evening and Tuesday morning 
  commutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. In Illinois, the latest 
road conditions can be obtained at www.gettingaroundillinois.com. In 
Missouri, the latest road conditions can be obtained at 
traveler.modot.org/map or by calling 1-888-275-6636.

&&

$$

MOZ018-026-034-042-172045-
/O.CAN.KLSX.WW.Y.0005.000000T0000Z-250218T0000Z/
Knox MO-Shelby MO-Monroe MO-Audrain MO-
Including the cities of Mexico
144 PM CST Mon Feb 17 2025

...WINTER WEATHER ADVISORY IS CANCELLED...

Accumulating snow is diminishing this afternoon. While additional 
light snow will be possible overnight, the ongoing Winter Weather 
Advisory is no longer necessary in these areas.

$$

MOZ072>075-084-085-099-181045-
/O.CON.KLSX.WS.W.0004.250218T0900Z-250219T1200Z/
Crawford MO-Washington MO-Saint Francois MO-Sainte Genevieve MO-
Iron MO-Madison MO-Reynolds MO-
Including the cities of Farmington
144 PM CST Mon Feb 17 2025

...WINTER STORM WARNING REMAINS IN EFFECT FROM 3 AM TUESDAY TO 6 AM 
CST WEDNESDAY...

* WHAT...Heavy snow expected. Total snow accumulations between 5 and 
  10 inches.

* WHERE...Portions of east central and southeast Missouri.

* WHEN...From 3 AM Tuesday to 6 AM CST Wednesday.

* IMPACTS...Travel could be very difficult to impossible. The 
  hazardous conditions could impact the Tuesday morning and evening 
  commutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The rapid accumulation of snow will make travel extremely difficult, 
if not impossible. If travel is necessary, be sure to exercise 
extreme caution. If you must travel, keep an extra flashlight, food 
and water in your vehicle in case of an emergency. The latest road 
conditions can be obtained at traveler.modot.org/map or by calling 
1-888-275-6636.

&&

$$

ILZ064-069-070-074-079-098-100>102-MOZ047>052-059>065-181045-
/O.UPG.KLSX.WS.A.0003.250218T0900Z-250219T1200Z/
/O.NEW.KLSX.WW.Y.0006.250218T0600Z-250219T1200Z/
Bond IL-Clinton IL-Marion IL-Washington IL-Randolph IL-Calhoun IL-
Madison IL-Saint Clair IL-Monroe IL-Moniteau MO-Cole MO-Osage MO-
Callaway MO-Montgomery MO-Lincoln MO-Gasconade MO-Warren MO-Saint
Charles MO-Franklin MO-Saint Louis MO-Saint Louis City MO-
Jefferson MO-
Including the cities of Chester, Saint Charles, Sullivan,
Cahokia, Centralia, Salem, Jefferson City, Union, Alton, Fulton,
Belleville, Saint Louis, Edwardsville, Sparta, and Washington
144 PM CST Mon Feb 17 2025

...WINTER WEATHER ADVISORY IN EFFECT FROM MIDNIGHT TONIGHT TO 6 AM 
CST WEDNESDAY...

* WHAT...Snow expected. Total snow accumulations between 2 and 5 
  inches.

* WHERE...Portions of south central and southwest Illinois and 
  central and east central Missouri.

* WHEN...From midnight tonight to 6 AM CST Wednesday.

* IMPACTS...Travel could be very difficult. The hazardous conditions 
  could impact the Tuesday morning and evening commutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. In Illinois, the latest 
road conditions can be obtained at www.gettingaroundillinois.com. In 
Missouri, the latest road conditions can be obtained at 
traveler.modot.org/map or by calling 1-888-275-6636.

&&

$$

ILZ095-MOZ019-027-035-180000-
/O.CON.KLSX.WW.Y.0005.000000T0000Z-250218T0000Z/
Adams IL-Lewis MO-Marion MO-Ralls MO-
Including the cities of Hannibal and Quincy
144 PM CST Mon Feb 17 2025

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 6 PM CST THIS 
EVENING...

* WHAT...Snow. Additional snow accumulations up to one inch.

* WHERE...In Illinois, Adams IL County. In Missouri, Lewis MO, 
  Marion MO, and Ralls MO Counties.

* WHEN...Until 6 PM CST this evening.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the Monday evening commute.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. In Illinois, the latest 
road conditions can be obtained at www.gettingaroundillinois.com. In 
Missouri, the latest road conditions can be obtained at 
traveler.modot.org/map or by calling 1-888-275-6636.

&&

$$

BRC

722 
WWUS43 KLSX 180818
WSWLSX

URGENT - WINTER WEATHER MESSAGE
National Weather Service St Louis MO
218 AM CST Tue Feb 18 2025

MOZ072>075-084-085-099-182330-
/O.CON.KLSX.WS.W.0004.250218T0900Z-250219T1200Z/
Crawford MO-Washington MO-Saint Francois MO-Sainte Genevieve MO-
Iron MO-Madison MO-Reynolds MO-
Including the cities of Farmington
218 AM CST Tue Feb 18 2025

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM CST WEDNESDAY...

* WHAT...Heavy snow expected. Total snow accumulations between 5 and 
  10 inches with locally higher amounts possible.

* WHERE...Portions of east central and southeast Missouri.

* WHEN...Until 6 AM CST Wednesday.

* IMPACTS...Travel could be very difficult to impossible. The 
  hazardous conditions could impact the Tuesday morning and evening 
  commutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The rapid accumulation of snow will make travel extremely difficult, 
if not impossible. If travel is necessary, be sure to exercise 
extreme caution. If you must travel, keep an extra flashlight, food 
and water in your vehicle in case of an emergency. The latest road 
conditions can be obtained at traveler.modot.org/map or by calling 
1-888-275-6636.

&&

$$

ILZ064-069-070-074-079-098-100>102-MOZ041-047>052-059>065-182330-
/O.CON.KLSX.WW.Y.0006.000000T0000Z-250219T1200Z/
Bond IL-Clinton IL-Marion IL-Washington IL-Randolph IL-Calhoun IL-
Madison IL-Saint Clair IL-Monroe IL-Boone MO-Moniteau MO-Cole MO-
Osage MO-Callaway MO-Montgomery MO-Lincoln MO-Gasconade MO-Warren
MO-Saint Charles MO-Franklin MO-Saint Louis MO-Saint Louis City
MO-Jefferson MO-
Including the cities of Washington, Cahokia, Salem, Columbia,
Saint Louis, Saint Charles, Sullivan, Edwardsville, Centralia,
Alton, Jefferson City, Union, Chester, Belleville, Fulton, and
Sparta
218 AM CST Tue Feb 18 2025

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 6 AM CST 
WEDNESDAY...

* WHAT...Snow. Additional snow accumulations between 1 and 5 inches.

* WHERE...Portions of south central and southwest Illinois and 
  central and east central Missouri.

* WHEN...Until 6 AM CST Wednesday.

* IMPACTS...Travel could be very difficult. The hazardous conditions 
  could impact the Tuesday morning and evening commutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. In Illinois, the latest 
road conditions can be obtained at www.gettingaroundillinois.com. In 
Missouri, the latest road conditions can be obtained at 
traveler.modot.org/map or by calling 1-888-275-6636.

&&

$$

Pfahler

571 
WWUS43 KLSX 182124
WSWLSX

URGENT - WINTER WEATHER MESSAGE
National Weather Service St Louis MO
324 PM CST Tue Feb 18 2025

MOZ072>075-084-085-099-191200-
/O.CON.KLSX.WS.W.0004.000000T0000Z-250219T1200Z/
Crawford MO-Washington MO-Saint Francois MO-Sainte Genevieve MO-
Iron MO-Madison MO-Reynolds MO-
Including the cities of Farmington
324 PM CST Tue Feb 18 2025

...WINTER STORM WARNING REMAINS IN EFFECT UNTIL 6 AM CST WEDNESDAY...

* WHAT...Heavy snow. Additional snow accumulations between 4 and 6 
  inches.

* WHERE...Portions of east central and southeast Missouri.

* WHEN...Until 6 AM CST Wednesday.

* IMPACTS...Travel could be very difficult. The hazardous conditions 
  could impact the Tuesday evening and Wednesday morning commutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

The rapid accumulation of snow will make travel extremely difficult, 
if not impossible. If travel is necessary, be sure to exercise 
extreme caution. If you must travel, keep an extra flashlight, food 
and water in your vehicle in case of an emergency. The latest road 
conditions can be obtained at traveler.modot.org/map or by calling 
1-888-275-6636.

&&

$$

ILZ064-069-070-074-079-098-100>102-MOZ041-047>052-059>065-191200-
/O.CON.KLSX.WW.Y.0006.000000T0000Z-250219T1200Z/
Bond IL-Clinton IL-Marion IL-Washington IL-Randolph IL-Calhoun IL-
Madison IL-Saint Clair IL-Monroe IL-Boone MO-Moniteau MO-Cole MO-
Osage MO-Callaway MO-Montgomery MO-Lincoln MO-Gasconade MO-Warren
MO-Saint Charles MO-Franklin MO-Saint Louis MO-Saint Louis City
MO-Jefferson MO-
Including the cities of Chester, Sparta, Alton, Belleville, Saint
Charles, Centralia, Fulton, Salem, Union, Sullivan, Edwardsville,
Washington, Saint Louis, Columbia, Jefferson City, and Cahokia
324 PM CST Tue Feb 18 2025

...WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 6 AM CST 
WEDNESDAY...

* WHAT...Snow. Additional snow accumulations between 1 and 3 inches.

* WHERE...Portions of south central and southwest Illinois and 
  central and east central Missouri.

* WHEN...Until 6 AM CST Wednesday.

* IMPACTS...Plan on slippery road conditions. The hazardous 
  conditions could impact the Tuesday evening and Wednesday morning 
  commutes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Slow down and use caution while traveling. In Illinois, the latest 
road conditions can be obtained at www.gettingaroundillinois.com. In 
Missouri, the latest road conditions can be obtained at 
traveler.modot.org/map or by calling 1-888-275-6636.

&&

$$

Carney

230 
WWUS43 KLSX 190854
WSWLSX

URGENT - WINTER WEATHER MESSAGE
National Weather Service St Louis MO
254 AM CST Wed Feb 19 2025

MOZ072>075-084-085-099-191000-
/O.CAN.KLSX.WS.W.0004.000000T0000Z-250219T1200Z/
Crawford MO-Washington MO-Saint Francois MO-Sainte Genevieve MO-
Iron MO-Madison MO-Reynolds MO-
Including the cities of Farmington
254 AM CST Wed Feb 19 2025

...WINTER STORM WARNING IS CANCELLED...

Accumulating snow has ended across the region. Travel impacts are 
expected to linger through the morning commute with many roads still 
snow-covered.

$$

ILZ064-069-070-074-079-098-100>102-MOZ041-047>052-059>065-191000-
/O.CAN.KLSX.WW.Y.0006.000000T0000Z-250219T1200Z/
Bond IL-Clinton IL-Marion IL-Washington IL-Randolph IL-Calhoun IL-
Madison IL-Saint Clair IL-Monroe IL-Boone MO-Moniteau MO-Cole MO-
Osage MO-Callaway MO-Montgomery MO-Lincoln MO-Gasconade MO-Warren
MO-Saint Charles MO-Franklin MO-Saint Louis MO-Saint Louis City
MO-Jefferson MO-
Including the cities of Centralia, Salem, Alton, Fulton, Saint
Charles, Washington, Columbia, Jefferson City, Edwardsville,
Sparta, Belleville, Cahokia, Union, Saint Louis, Sullivan, and
Chester
254 AM CST Wed Feb 19 2025

...WINTER WEATHER ADVISORY IS CANCELLED...

Accumulating snow has ended across the region. Travel impacts are 
expected to linger through the morning commute with many roads still 
snow-covered.

$$

Pfahler

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1050 PM CST Sun Feb 16 2025

.KEY MESSAGES...

- Light snow will bring minor accumulations to portions of northeast
  Missouri and west-central Illinois Monday. A Winter Weather Advisory
  was issued for locations of northeast Missouri, where up to 2 inches
  of snow is possible.

- A round of more significant snowfall is likely (60+ percent)
  Tuesday into Tuesday night. A Winter Storm Watch has been issued for
  portions of the area that could see in excess of 5 inches of
  snowfall by early Wednesday morning.

- Frigid temperatures will maintain their grip on the area through
  the upcoming week. A large majority of locations will not rise above
  32 degrees until next Saturday. Sub-zero wind chills will become
  widespread Tuesday through Thursday.

&&

.SHORT TERM...  (Through Late Monday Night)
Issued at 345 PM CST Sun Feb 16 2025

The system that brought rain/snow to the region Saturday into
this morning will continue to depart to the east as surface high
pressure builds in out of the northern and central Plains. A few
snow flurries are possible under the thicker cloud cover until
drier air works in aloft from approximately 900 MB. Short range
model guidance soundings show a shallow layer of saturation
centered around 925 MB that may hold onto cloud cover a bit longer
to the east of the Mississippi River.

Clearing might lead to more efficient cooling if it weren't short-
lived. Clouds thicken from west to east late tonight into early
Monday morning as a weak push of mid-level warm air advection lifts
into central and northern Missouri. A weak wing of mid-level forcing
initially stretches across northern Missouri in conjunction with the
axis of 80-90% RH values. Chances (20-40%) for light snow begin
around 12z Monday morning over central and northeast Missouri with a
couple of caveats.

Although mid and upper levels saturate by 12z, saturation below 850
MB will lag by a few hours with greater depth and magnitude to dry
air along and east of the Mississippi River. Very light snow could
begin as early as 12z, depending on how quickly low levels saturate.
By 15z, this should be overcome with light snow impacting sections
of northeast Missouri into far west-central Illinois through mid-
afternoon before mid-level forcing weakens and begins to shift
south. NAM/RAP/HRRR all plot around 0.05-0.10 of QPF with some
slight variance in eastward extent and north to south position of
the forcing. In general, the highest confidence for snowfall
accumulations approaching 2 inches is across the far northwest
counties where HREF probabilities for 1 inch amounts reach 60%.
Probabilities for 2 inches are below 10% with these amounts more so
localized to the border with NWS Kansas City. Considering the
abundance of cold air dropping ground surfaces below freezing and
timing of the Monday morning commute, a Winter Weather Advisory was
issued for the far northwest section of the CWA from 12z Monday to
00z Tuesday. The steadiest snowfall should come in the early half of
the advisory period, tapering to lighter snowfall in the afternoon.
Slick conditions will be possible, especially in and around the
advisory.

The next system begins to approach from the Plains with a broad area
of very weak mid-level lift shifting south through the night. A few
flurries or brief period of light snow is possible, but the higher
impact for the next system is expected to hold off until Tuesday.

Carney

&&

.LONG TERM...  (Tuesday through Next Sunday)
Issued at 345 PM CST Sun Feb 16 2025

The period starts off with a snowfall event that has the potential
to result in the greatest impact of the forecast stretch. The
timeframe has begun to land inside the tail end of the medium range
guidance and while there is still come variation in exact location
of snowfall maximums, a general consensus is coming more into line
across southern section of Missouri and Illinois, where 5+ inches of
snowfall could accumulate in a 24 hour period be Tuesday morning and
early Wednesday morning.

The weak mid-level shortwave that passes over northern Missouri
Monday will effectively shunt the weak corridor of mid-level
frontogenesis southward into central Missouri early Tuesday morning.
Meanwhile, an upper level trough and broad area of 500 MB vorticity
crosses the central Rockies, giving rise to surface low centered
around the Texas/Oklahoma border with a corresponding 850 MB low
departed to the north over northern Oklahoma. As the surface low
tracks east, moisture is pulled northward from the Gulf and eject
over top an established arctic air mass. This will result in
widespread snowfall accumulations reaching well into Missouri and
Illinois Tuesday into Tuesday night.

It'll be interesting to watch the mid-level frontogenetic behavior as
it becomes reinvigorated by the approaching mid-level low in
addition to enhancing moisture and lift aloft. The very cold
temperatures will deepen the dendritic growth zone from the surface
through just below 500 MB. Where the lift is allocated within the
depth of the DGZ will have an impact in the efficiency of snowfall
rates and accumulations. Lift is maximized between 500-700 MB and
trails off near the surface with the surface low departed so far to
the south. That being said, where lift is maximized, winds increase
to around 50-55 kts at the top of the DGZ. This may cause fracturing
aloft, leading to lower snow-to-liquid ratios. While lift does
decrease lower in the column toward the surface, there is some
semblance of at least weak to modest lift where winds are decoupled
from the higher altitudes. This complicates an exact snow-to-liquid
ratio a bit. However, a rough 12-15:1 average would need to yield
0.30-0.40 of QPF for warning criteria accumulations (5 inches).

LREF ensembles show QPF means of 0.30 of an inch running along the I-
70 corridor with 0.40 of an inch extending from just south of
Jefferson City to Sullivan and Festus, east-southeastward into
southwest Illinois. LREF probabilities for 0.30 of an inch are at or
above 60% roughly along and south of I-70 in Missouri and I-64 in
Illinois. The mid-level fgen feature is likely to provide a boost in
snowfall efficiency with snowfall rates that could exceed 1 inch per
hour at times Tuesday afternoon into Tuesday evening. While this
morning's NAM shifted this axis slightly north, the latest 18z
shifted more in line with global guidance that has been rather
consistent over the past several runs. Southern sections of the
forecast area are the most likely to receive impactful snowfall with
LREF probabilities for 5+ inches at 50% or higher over southern
sections of the CWA. While probabilities begin to fall off around I-
70, a Winter Storm Watch was warranted up through the I-70 corridor
to account for any potential northward shift. The highest snowfall
rates are expected to fall between 18z Tuesday and 06z Wednesday.
Wind gusts of 20-25 mph could lead to blowing and drifting with the
light, powdery nature consistency of the accumulation.

The remainder of the period is locked into the arctic air mass with
temperature that remain well below freezing through Friday. Wind
chills well below zero will become common Tuesday morning and expand
southward Wednesday with the entire area in the single digits to
teens below zero. Wind chills may approach 20 below zero over
central and northern Missouri at times Thursday morning.

Carney

&&

.AVIATION...  (For the 06z TAFs through 06z Monday Night)
Issued at 1040 PM CST Sun Feb 16 2025

VFR flight conditions are expected to prevail across the area
until Monday morning. Ceilings will lower to MVFR mainly along
and north of the Missouri River and I-64 in Illinois through the
day. A band of snow will also lower the visibility to MVFR/IFR
primarily across parts of central and northeast Missouri as well
as west central Illinois. The snow band will weaken and likely
diminish to flurries across extreme northeast Missouri and west
central Illinois during the evening, although MVFR ceilings will
continue to prevail, and spread southward over almost the entire
area area by 06Z Tuesday.

Carney

&&

.CLIMATE...
Issued at 230 PM CST Fri Feb 14 2025

Record low temperatures are possible late next week. Here's a list
of some of the record low temperatures during the coldest period
of the forecast.

          ST LOUIS         COLUMBIA         QUINCY
Feb 19   -3 in 1936       -6 in 1903      -11 in 1903
Feb 20   -4 in 1885        0 in 1929       -3 in 1929

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Winter Storm Watch from late Monday night through late Tuesday
     night for Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin
     MO-Gasconade MO-Iron MO-Jefferson MO-Lincoln MO-Madison MO-
     Moniteau MO-Montgomery MO-Osage MO-Reynolds MO-Saint
     Charles MO-Saint Francois MO-Saint Louis City MO-Saint
     Louis MO-Sainte Genevieve MO-Warren MO-Washington MO.

     Winter Weather Advisory from 6 AM to 6 PM CST Monday for Audrain
     MO-Boone MO-Knox MO-Monroe MO-Shelby MO.

IL...Winter Storm Watch from late Monday night through late Tuesday
     night for Bond IL-Calhoun IL-Clinton IL-Madison IL-Marion
     IL-Monroe IL-Randolph IL-Saint Clair IL-Washington IL.

&&

WFO LSX

Hazardous Weather Outlook
National Weather Service St Louis MO
359 PM CST Sun Feb 16 2025

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-172200-
Greene IL-Macoupin IL-Montgomery IL-Bond IL-Fayette IL-Clinton IL-
Marion IL-Washington IL-Randolph IL-Adams IL-Brown IL-Pike IL-
Calhoun IL-Jersey IL-Madison IL-Saint Clair IL-Monroe IL-Knox MO-
Lewis MO-Shelby MO-Marion MO-Monroe MO-Ralls MO-Pike MO-Boone MO-
Audrain MO-Moniteau MO-Cole MO-Osage MO-Callaway MO-Montgomery MO-
Lincoln MO-Gasconade MO-Warren MO-Saint Charles MO-Franklin MO-
Saint Louis MO-Saint Louis City MO-Jefferson MO-Crawford MO-
Washington MO-Saint Francois MO-Sainte Genevieve MO-Iron MO-
Madison MO-Reynolds MO-
359 PM CST Sun Feb 16 2025

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

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

Light snow is expected on Monday, generally along and north of I-70.
Snowfall accumulations of 1 to 2 inches are possible across parts of
central and northeast Missouri, and a Winter Weather Advisory is in
effect for those locations.

Accumulating snowfall is expected across much of the area on Tuesday
and Tuesday night. The heaviest snow is expected along and south of
I-70 where 5+ inches of snow is possible. A Winter Storm Watch is in
effect on Tuesday and Tuesday night for those locations.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

Carney