Severe Thunderstorm Warning 81, NWS St. Louis, MO

184 
WWUS53 KLSX 312037
SVSLSX

Severe Weather Statement
National Weather Service St Louis MO
337 PM CDT Tue May 31 2022

MOC019-312100-
/O.CON.KLSX.SV.W.0081.000000T0000Z-220531T2100Z/
Boone MO-
337 PM CDT Tue May 31 2022

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 400 PM CDT
FOR CENTRAL BOONE COUNTY...

At 335 PM CDT, a severe thunderstorm was located over Columbia,
moving east 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.

Locations impacted include...
  Murry.

This also includes Finger Lakes State Park and Jewell Cemetery
Historic Site.
 
This includes Interstate 70 in Missouri between exits 121 and 133.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3905 9249 3918 9211 3907 9211 3906 9213
      3904 9213 3903 9214 3902 9213 3892 9216
      3891 9243
TIME...MOT...LOC 2035Z 258DEG 26KT 3896 9235 

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

$$

Carney

Area Forecast Discussion
National Weather Service Saint Louis MO
248 PM CDT Tue May 31 2022

.SHORT TERM...  (Through Late Wednesday Night)
Issued at 246 PM CDT Tue May 31 2022

Key Messages:

1.) Strong to severe thunderstorms remain possible from now through
3 am, primarily along and north of I-44 in MO and I-70 in IL. The
main hazards with these thunderstorms will be damaging winds and
large hail, but a brief tornado cannot be ruled out. Where
thunderstorms train/backbuild, locally heavy rainfall could result
in isolated flash flooding.

2.) There is potential for a strong to severe thunderstorm or two
and locally heavy Wednesday afternoon into evening across
southeastern MO and southwestern IL but will be dictated by the
effective cold front's position, which may be south of the CWA by
that time.

First and foremost, there is still uncertainty in exactly how
thunderstorms will evolve this afternoon through tonight. Showers
and thunderstorms have persisted across the western half of MO this
afternoon much longer than any CAMs anticipated and have resulted in
the development of an MCV near the KS-MO border as of 19z. To the
east and southeast of ongoing thunderstorms and the MCV, surface
heating of an airmass characterized by mid-60s to near 70 F
dewpoints has yielded MLCAPE exceeding 1500 J/kg across much of the
region and an extensive cumulus field. The instability could lead to
re-intensification of the ongoing thunderstorms early this afternoon
moving toward northeastern MO and west-central IL. However, the
greatest focus of thunderstorm development this afternoon and
evening will be along remnant outflow that these thunderstorms
deposit amidst weak WAA within a LLJ and relatively deeper ascent
downstream of the aforementioned MCV. This development is most
likely to occur from central MO to west-central IL.

A mid-level jet streak has also managed overlap a small corridor of
the unstable warm sector, leading to 30 to 40 kt of deep-layer wind
shear. This wind shear should be sufficient to allow thunderstorms
to become organized into multicell clusters, but low-level veering
ahead of the MCV expected to track through northern MO may allow a
brief supercell or two to develop. A relatively well-mixed boundary
layer and DCAPE near 1000 J/kg suggest that damaging downburst winds
will be possible, but bowing segments within the multicell clusters
that can become orthogonal to an around 30-kt 0 to 3 km shear vector
pointed to the northeast could further enhance the threat of
damaging winds. Large hail could also accompany the deepest updrafts
with 6 to 7 C/km mid-level lapse rates. Low-level wind shear is
anticipated to generally be weak, but a brief supercell or QLCS
tornado cannot be ruled out. Lastly, locally heavy rainfall with
training/backbuilding thunderstorms is also possible with anomalous
PW, deep-layer flow nearly paralleling surface boundaries, and LLJ
potentially perpendicular to the multicell clusters. Although
antecedent conditions are not particularly wet, persistent locally
heavy rainfall may still lead to isolated flash flooding.

Thunderstorms will gradually progress southeastward overnight, but
they will likely weaken and become outflow dominant with time as
instability decreases and thunderstorms move south of the stronger
deep-layer wind shear. However, some showers and thunderstorms could
linger into Wednesday morning along and south of I-70. This early
day precip and abundant cloud cover could shunt the effective
surface cold front southward into southeastern MO and
southwestern IL through the morning, perhaps even just south of
the CWA. As a mid- level perturbation/MCV passes through the
region sometime during the late afternoon through evening, another
round of showers and thunderstorms is likely to develop. If the
augmented surface cold front remains in southeastern MO and
southwestern IL during this time and destabilization occurs on its
warm side, a few strong to severe thunderstorms will be possible
in those areas along with locally heavy rainfall. However, the
position of this front during that time is currently unclear.
Showers and a few thunderstorms may continue through Thursday
night at times as mid- level height falls ahead of an approaching
upper-level trough generate weak large-scale ascent.

Pfahler

.LONG TERM...  (Thursday through Next Tuesday)
Issued at 246 PM CDT Tue May 31 2022

There is disagreement among model guidance on how progressive the
850-hPa front will be late Wednesday night into Thursday, which will
determine if showers and a few thunderstorms linger into Thursday
morning. This evolution will be partially tied to the amplitude and
timing of an upper-level trough, influencing the front's
advancement. However, by the second half of the day, dry and
tranquil conditions are expected with neutral/slightly rising mid-
level height tendencies aiding upper-level northwesterly flow above
an arriving surface/low-level anticyclone collocated with a
seasonably cool airmass. This anticyclone will dominate the mid-
Mississippi River Valley through Friday.

Global model guidance are in consensus that an upper-level shortwave
trough will navigate the northwesterly flow late Saturday into
Sunday but differ in their depictions of its amplitude/sharpness.
Ahead of this shortwave trough, the aforementioned anticyclone will
be quickly shunted to the east of the region allowing low-level
southerly flow advect warm air and create a channel for Gulf of
Mexico moisture transport northward. An active thunderstorm pattern
could begin somewhere across the Midwest late Saturday into Sunday
as attendant shortwave trough ascent interacts with an increasingly
warm, moist, and potentially unstable airmass, especially if the
shortwave is more amplified and sharp. This pattern could continue
into early next week as additional upper-level troughs may pass and
the airmass could remain intact, but global model guidance begin to
diverge in the details of the upper-level flow pattern across the
CONUS beyond Sunday.

Pfahler

&&

.AVIATION...  (For the 18z TAFs through 18z Wednesday Afternoon)
Issued at 1254 PM CDT Tue May 31 2022

The short-term concern this TAF period will be the evolution of
thunderstorms moving northeastward from west-central MO. These
thunderstorms have the potential to impact KUIN later this afternoon
as they possibly re-intensify. Otherwise, additional showers and
thunderstorms will develop through the afternoon and evening, slowly
progressing eastward with time. Exact timing and evolution of these
thunderstorms is uncertain and the current TAF depicts the most
likely periods of thunderstorm impacts, with earlier onset times not
out of the question. The most intense thunderstorms will be capable
of hail and strong winds along with brief reductions to IFR flight
conditions. Showers and thunderstorms may continue into early
Wednesday at St. Louis metro terminals.

MVFR stratus is indicated to develop across portions of the area
late tonight/Wednesday morning, threatening all terminals for at
least a period of time. However, this stratus/stratocumulus may tend
to lift and scatter through afternoon. Another round of showers
and thunderstorms could develop Wednesday afternoon into evening
but is currently expected to largely remain south of all
terminals. Otherwise, southerly winds today will veer to the
north- northwest late tonight through Wednesday morning as a cold
front reaches the region.

Pfahler

&&

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

WFO LSX

Hazardous Weather Outlook
National Weather Service Saint Louis MO
303 PM CDT Tue May 31 2022

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-012015-
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-
303 PM CDT Tue May 31 2022

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

.DAY ONE...Tonight.

Strong to severe thunderstorms are possible into tonight, especially
across central and northeastern Missouri as well as west-central
Illinois. Damaging winds and large hail being the main hazards with
thunderstorms. However, a brief tornado cannot be ruled out. Locally
heavy rainfall could result in isolated flash flooding as well.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

Thunderstorms are likely Wednesday into Thursday morning, mainly
south of I-70.

There is a chance of thunderstorms across the region again late
Saturday through Monday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon into tonight.

Pfahler