Severe Thunderstorm Warning 18, NWS St. Louis, MO

774 
WWUS53 KLSX 250154
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
854 PM CDT Sun Apr 24 2022

MOC187-250204-
/O.CAN.KLSX.SV.W.0018.000000T0000Z-220425T0230Z/
St. Francois MO-
854 PM CDT Sun Apr 24 2022

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN ST. FRANCOIS
COUNTY IS CANCELLED...
    
The severe thunderstorm which prompted the warning has moved out of 
the warned area. Therefore, the warning has been cancelled.

LAT...LON 3770 9016 3775 9021 3790 9003 3784 8997
      3781 9001 3773 9007
TIME...MOT...LOC 0154Z 237DEG 26KT 3774 9013 

$$

MOC186-250230-
/O.CON.KLSX.SV.W.0018.000000T0000Z-220425T0230Z/
Ste. Genevieve MO-
854 PM CDT Sun Apr 24 2022

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 930 PM CDT
FOR SOUTHEASTERN STE. GENEVIEVE COUNTY...

At 854 PM CDT, a severe thunderstorm was located near Coffman, moving
northeast at 30 mph.

HAZARD...60 mph wind gusts and quarter size hail.

SOURCE...Radar indicated.

IMPACT...Hail damage to vehicles is expected. Expect wind damage to 
         roofs, siding, and trees.

This severe thunderstorm will remain over mainly rural areas of
southeastern Ste. Genevieve County, including the following
locations... Minnith.

This includes Interstate 55 in Missouri between exits 141 and 143.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3770 9016 3775 9021 3790 9003 3784 8997
      3781 9001 3773 9007
TIME...MOT...LOC 0154Z 237DEG 26KT 3774 9013 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...60 MPH

$$

Pfahler

395 
WWUS53 KLSX 250203
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
903 PM CDT Sun Apr 24 2022

MOC186-250213-
/O.CAN.KLSX.SV.W.0018.000000T0000Z-220425T0230Z/
Ste. Genevieve MO-
903 PM CDT Sun Apr 24 2022

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN STE. GENEVIEVE
COUNTY IS CANCELLED...
                
The storm which prompted the warning has weakened below severe
limits, and no longer poses an immediate threat to life or property.
Therefore, the warning has been cancelled.

LAT...LON 3770 9016 3775 9021 3790 9003 3784 8997
      3781 9001 3773 9007
TIME...MOT...LOC 0201Z 237DEG 26KT 3778 9006 

$$

Pfahler

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
623 PM CDT Sun Apr 24 2022

.SHORT TERM...  (Through Late Monday Night)
Issued at 254 PM CDT Sun Apr 24 2022

The main issue will be the convective potential this afternoon into
early this evening. There is also the potential for locally heavy
rain with additional activity that moves through overnight.

Early this morning, scattered showers dotted the landscape in a
general north/south orientation, weakening and decreasing in
coverage from mid to late morning. This activity ran along and ahead
of a cold front and remnant outflow from last night's thunderstorms
which initially developed over the eastern Plains. This frontal
boundary extended well south of an occluded surface low that now
resides over the Upper Midwest. Though the initial showers did not
have much an impact themselves, the resulting cloud cover that
shrouded the region through much of the day has limited surface
instability this afternoon. There have been some breaks in the
cloud cover ahead of the front but sunshine has been limited.

Visible satellite shows broken/overcast skies running from the Great
Lakes southwestward through central Illinois and southeast sections
of Missouri. Surface analysis shows the cold front has made steady
but slow progress to the southeast through the day, but in the
last couple of hours there has been a hint that the boundary is
stalling or even attempting to return north. Surface temperatures
over southeast and east-central Missouri and southwest Illinois
are in the mid to upper 70s with dewpoints in the low-60s. Winds
veer to the west over central Missouri, where temperatures fall
into the 50s and dewpoints drop into the upper 30s/low-40s.

Latest trends show the cold front has slowed up considerably with
even a hint that it may be meandering slightly north. Though
activity was expected along the front, SPC mesoanalysis hasn't been
that impressive regarding concerns for severe thunderstorms. Warmth
and moisture are in place, along with effective shear of 40-45
knots. The limiting factors have been the forcing with the
slow/stalling boundary and mid-level lapse rates that have been
conditionally unstable at best. This was proven in the earlier
isolated/scattered showers and thunderstorms that prompted the
severe thunderstorm watch. Each exhibit brief periods of promise,
showing weak rotation 100-150 SRH along the boundary, but had little
upward vertical growth to reach their full potential. As we continue
to work through the remainder of the afternoon/evening, the threat
for severe weather seems to be waning, mainly with the lack of
forcing, weakening lapse rate and lessening threat for instability
to recover with lowering sun angle. Additionally, showers and
thunderstorm well to the southwest continue to throw "debris clouds"
to the northeast, which may only continue to inhibit further
potential. Marginally severe hail and wind seem to be the greatest
threat. However, soundings depict long, narrow CAPE, which doesn't
support much in the way of hail, especially with the meager mid-
level lapse rate of around 6.5C. Thinking is that the severe
threat, while not zero, is beginning to diminish quickly with each
passing hour.

The suite of hi-res guidance and HREF paintball plots lend
confidence to additional showers and an embedded thunderstorm
this evening into the overnight period. I believe we will
transition from a strong to severe thunderstorm threat to a
localized heavy rain threat. Then, there are even caveats to this,
too. While PWATs are progged to be in the 1.4-1.8" range, when
surface flow is overlaid with mean mid-level flow, parallel flow
is spatially and temporally limited in scope. It looks like there
will be an uptick in activity as an upper level shortwave pushes
northeast overhead and the surface boundary slow sags south. How
far the front makes it south will be key in just how much
residence time there is for locally heavy rain to train. As
limited as this is, the greatest chances for heavy rain still look
to line up over southeast Missouri and southwest Illinois.

By Monday morning, the upper wave jaunts east, influencing the
southward push of the surface boundary as northwest flow takes over.
Rain potential will decrease through Monday morning with skies
clearing from west to east. Below normal temperatures are expected
with highs in the mid-50s to low-60s.

Maples

.LONG TERM...  (Tuesday through Next Sunday)
Issued at 254 PM CDT Sun Apr 24 2022

Long term trends will bring the early week below normal temperatures
back to near normal by midweek and potentially above normal later in
the week. Though the period starts out dry, rain chance will
increase from mid-to-late week.

Surface high pressure will build into the region, tucking underneath
the base of an upper level trough through the day Tuesday. North-
northwest flow will persist from the surface through the mid and
upper levels with the 850 mb 0C isotherm bisecting the CWA. This
will ensure one more day of below normal temperatures. There could
be impacts from the colder morning temperatures, which start out
near freezing over northeast Missouri and trend slightly upward to
around 40 degrees over southeast Missouri and southwest Illinois.
Frost potential remains a concern Tuesday morning with highs only
return to the upper 50s to low-60s. Cooler air will extend
through Tuesday night, but may not be quite as cold with mid-30s
to low-40s.

Surface high pressure begins to move east Wednesday as mid/upper
ridging builds west to east across the central Plains. This will
result in return flow Wednesday, inching temperatures closer to
normal (mid-60s to low-70s). Southerly flow and dewpoints in the mid-
30s to low-40s may be enough argument for a slight bump in highs.
The reservation is in the south (vs. southwest) wind and recent
green-up, lending a bit more of a challenge to over performance.

Upper ridging continues to build in from the west from Thursday into
next weekend. As this occurs, an upper level shortwave moves east
through the upper trough in tandem with mid-level warm air
advection. A weak surface low develops over the central Plains,
but it holds far enough west, while surface ridging retains enough
influence that Thursday's rain potential should remain west of
the Mississippi River. Better chances should hold off until late
in the week, but guidance diverges on strength and evolution with
an increased spread in ensemble data. There is some form of a
surface low deepening over the central Plains that ejects into the
Upper Midwest. The cold front makes relatively slow southeast
progress with plenty of question in the amount of support that
will be over the region at any give time. The main theme will be
toward more seasonable warmth with some magnitude of
shower/thunderstorms potential through the end of the week.

Maples

&&

.AVIATION...  (For the 00z TAFs through 00z Monday Evening)
Issued at 611 PM CDT Sun Apr 24 2022

Cold front is pushing through the St Louis metro as of 6PM (23Z).
Somewhat persistent showers are expected along and behind the
front extending deep into the night. Some occasional thunder is
also possible, although confidence in it occurring at a TAF site
is too low to mention. Eventually some MVFR ceilings are possible
in the St Louis metro and southward where more persistent rain
falls tonight, but this should be clearing by morning as drier air
continues to push in behind the front. By tomorrow winds will be
northwest area wide with some gusts to 15 to 20KT possible with
VFR conditions.

Kimble

&&

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

WFO LSX

Hazardous Weather Outlook
National Weather Service Saint Louis MO
659 PM CDT Sun Apr 24 2022

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-260000-
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-Saint Francois MO-Saint Louis City MO-Saint Louis MO-
Sainte Genevieve MO-Shelby MO-Warren MO-Washington IL-Washington MO-
659 PM CDT Sun Apr 24 2022

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

.DAY ONE...Tonight.

Showers and a few embedded thunderstorms are expected tonight.
Locally heavy rainfall is possible overnight primarily across
southeast Missouri and southwest Illinois.

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

There is a chance for thunderstorms across parts of the area early
Monday morning and again Thursday night through Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated tonight.

Kimble