Special Weather Statement, NWS St. Louis, MO

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1148 AM CST Sat Mar 9 2019

.SHORT TERM...  (Through Late Tonight)
Issued at 418 AM CST Sat Mar 9 2019

A sharp, slightly negatively tilted trough has pushed over the High
Plains, accompanied by a nearly 100kt mid level jet streak just
downstream from the base of the trough. At the surface, a deep low
has moved into western KS with a warm front stretching to the SE
into northern AR. This cyclone is progged to track to the NE, with
the center passing through NW MO this afternoon, bringing the threat
of heavy rain, severe thunderstorms, and strong non-thunderstorm
winds to the mid-Mississippi Valley.

Showers and storms associated with low to mid level warm air
advection have already pushed into western MO. This activity will
continue to spread eastward this morning as WAA and convergence
increase along the northward moving warm front. The elevated warm
moist advection ahead of the warm fropa will support MUCAPE up to
1000j/kg across southern MO and IL by late morning. This, coupled
with deep layer bulk shear near 60kts, opens the possibility for a
few strong to severe thunderstorms this morning. With meager
instability and elevated storms, the primary threat will be for
damaging winds, though some small hail cannot be ruled out.

The warm sector will finally push into the region sometime around
18z. Shortly after the warm fropa, a robust dry slot will slide into
the area from the southwest, creating a narrow widow in which
surface based storms will possible, especially in our extreme SE.
The short residence time within the warm sector and mostly cloudy
skies will limit MLCAPE to at most 500 J/kg in our far SE. However,
even with this limited instability, 0-1km shear in excess of 30kts
and 0-3 shear pushing 50kts does allow for the possibility of a few
tornadoes this afternoon.

As the dry slot sweeps through the region, it will end the
thunderstorms threat. However, the steep lapse rates within the dry
slot will allow for strong gradient winds to mix down to the
surface, setting the stage for a substantial wind event on the back
side of this storm. Accordingly, a wind advisory remains in effect
for this afternoon and evening. Winds will quickly taper off after
midnight as the low finally pushes northeast out of the area.

BSH

.LONG TERM...  (Sunday through Friday)
Issued at 418 AM CST Sat Mar 9 2019

Main focus through the forecast period will be precip chances for
Tues and Wed. Should also see a general warming trend through the
period.

With the surface low over the Great Lakes region continuing east, a
large surface ridge will build into the region Sun. Given the
cyclonic flow across at least the northeast half of the CWA, expect
clouds to linger through the morning hours. However, these clouds
should move east out of the area, and with strong insolation and
westerly winds during the afternoon, temps should warm into the
upper 40s to mid 50s. Going forecast may still be too cool, but some
question regarding how quickly clouds will move out of the area
remains. With similar setup for Mon, have kept temps similar as
well, although weak CAA will help offset the strong heating.

Upper pattern over the region becomes quite amplified Mon night with
strong WAA possibly bringing precip into western portions of the CWA
Tues morning. However, the GFS remains a fast outlier with the
ECMWF/GEM slower, and the FV3 only slightly slower. If precip can
move in as quickly as the GFS suggests, there is a possibility that
precip will begin as snow given wet bulb temps remaining below 0C.
However, with the strong WAA, this should be brief before changing
over to rain. Model solns do agree that surface temperatures will be
above freezing at the onset of rain. Rain should continue off and on
through Wed as the low deepens and pulls NE into the Great Lakes
region.

Expect temps to climb into the 60s on Wed and Thurs. With a surface
ridge building into the area for Thurs night and Fri, have low PoPs
for snow across northern portions of the CWA as the upper trof
swings through the region.

Tilly

&&

.AVIATION...  (For the 18z TAFs through 18z Sunday Afternoon)
Issued at 1139 AM CST Sat Mar 9 2019

Widespread area of showers and thunderstorms is in the process of
exiting the terminals as of 1730 UTC. IFR ceilings will remain
however over the next couple of hours along with the chance of
scattered showers. The dry slot will move into the region this
afternoon with a rapid improvement to VFR ceilings. Scattered
thunderstorms are possible at KCOU and KUIN late this afternoon
but the metro terminals should be too far southeast. The story
will then turn to the strengthening southwest winds. Sustained
winds of 20-30 mph with gusts of 40-50 mph are likely from very
late this afternoon through about midnight before slackening off.
Another period of MVFR ceilings is likely to affect the terminals
this evening through Sunday morning before lifting back to VFR.

SPECIFICS FOR KSTL:

Area of showers and thunderstorms has just exited the terminal,
with scattered showers possible over the next couple of hours. IFR
ceilings will give way rapidly to VFR conditions this afternoon,
along with a wind shift to the southwest. Southwest winds of 20-30
mph with gusts of 40-50 mph are likely beginning very late this
afternoon until about midnight before slackening off. Another
period of MVFR ceilings is likely from late this morning through
about mid morning on Sunday. VFR conditions with westerly winds
around 10-15mph are likely through the remainder of the valid TAF
period.

Gosselin

&&

.LSX WATCHES/WARNINGS/ADVISORIES...
MO...Wind Advisory until midnight CST tonight for Audrain MO-Boone MO-
     Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-
     Iron MO-Jefferson MO-Knox MO-Lewis MO-Lincoln MO-Madison MO-
     Marion MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO-Pike
     MO-Ralls MO-Reynolds MO-Saint Charles MO-Saint Louis City
     MO-Saint Louis MO-Shelby MO-Warren MO-Washington MO.

IL...Wind Advisory until midnight CST tonight for Adams IL-Bond IL-
     Brown IL-Calhoun IL-Fayette IL-Greene IL-Jersey IL-Macoupin
     IL-Madison IL-Montgomery IL-Pike IL.

&&

WFO LSX

Hazardous Weather Outlook
National Weather Service Saint Louis MO
346 AM CST Sat Mar 9 2019

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-101200-
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-
346 AM CST Sat Mar 9 2019

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

.DAY ONE...Today and tonight.

There is a chance for thunderstorms across the area. A few storms
may be severe through this afternoon mainly for southeast Missouri
and southern Illinois.

Strong southwest winds of 20 to 30 mph with gusts to 45 mph are
expected this afternoon and evening for much of the area. Please see
the Wind Advisory that has been issued for additional info.

.DAYS TWO THROUGH SEVEN...Sunday through Friday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed through this afternoon.

Tilly

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
1253 PM CST SAT MAR 9 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1248 PM     HAIL             5 E COLUMBIA            38.95N 92.23W
03/09/2019  E0.25 INCH       BOONE              MO   TRAINED SPOTTER

&&

MF

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
1258 PM CST SAT MAR 9 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1257 PM     HEAVY RAIN       2 NW MURPHY             38.51N 90.50W
03/09/2019  M1.36 INCH       ST. LOUIS          MO   PUBLIC

&&

MF

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
100 PM CST SAT MAR 9 2019

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1217 PM     HEAVY RAIN       1 SW FENTON             38.53N 90.47W
03/09/2019  M1.18 INCH       ST. LOUIS          MO   PUBLIC

&&

TES

Special Weather Statement
National Weather Service St Louis MO
133 PM CST SAT MAR 9 2019

MOZ048>050-092000-
Cole MO-Osage MO-Callaway MO-
133 PM CST SAT MAR 9 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN COLE...SOUTH CENTRAL
CALLAWAY AND CENTRAL OSAGE COUNTIES UNTIL 200 PM CST...

At 133 PM CST, Doppler radar was tracking a strong thunderstorm near
Brazito, moving east at 40 mph.

Dime size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Jefferson City, Linn, Wardsville, Taos, Westphalia, St. Thomas, Rich
Fountain, Brazito, Hickory Hill, Wainwright, Schubert, Osage City,
Osage Bend, Frankenstein, Tebbetts, Loose Creek and Bonnots Mill.

This also includes  Clarks Hill/Norton Historic Site.

LAT...LON 3867 9189 3840 9178 3832 9219 3834 9220
      3834 9222 3832 9224 3832 9226 3834 9229
      3834 9234 3847 9239
TIME...MOT...LOC 1933Z 252DEG 34KT 3841 9225

Britt

Special Weather Statement
National Weather Service St Louis MO
203 PM CST SAT MAR 9 2019

MOZ049>051-059-060-062-092030-
Montgomery MO-Gasconade MO-Franklin MO-Warren MO-Osage MO-
Callaway MO-
203 PM CST SAT MAR 9 2019

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN MONTGOMERY...
SOUTHEASTERN CALLAWAY...NORTHWESTERN FRANKLIN...OSAGE...NORTHWESTERN
WARREN AND NORTHERN GASCONADE COUNTIES UNTIL 230 PM CST...

At 203 PM CST, Doppler radar was tracking strong thunderstorms along
a line extending from Chamois to near Linn to near Freeburg. Movement
was east at 50 mph.

Dime size hail and wind gusts up to 50 mph will be possible with
these storms.

Locations impacted include...
Hermann, Linn, Belle, Jonesburg, Bland, Freeburg, Chamois, Rich
Fountain, Swiss, Big Spring, Mount Sterling, Drake, Gasconade,
Berger, High Hill, Argyle, Rhineland, Morrison, McKittrick and
Portland.

This includes Interstate 70 in Missouri near exit 183.

This also includes  Deutschheim Historic Site.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with these storms, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in St Louis.

&&

LAT...LON 3848 9189 3871 9186 3891 9126 3861 9128
      3829 9164 3829 9211
TIME...MOT...LOC 2003Z 256DEG 46KT 3866 9179 3850 9181 3833 9202

Britt