Flash Flood Watch 3, NWS St. Louis, MO

498 
WGUS63 KLSX 150946
FFALSX

Flood Watch
National Weather Service Saint Louis MO
446 AM CDT Fri May 15 2020

ILZ095>097-MOZ018-019-026-027-034>036-041-042-047-048-050-151100-
/O.EXP.KLSX.FF.A.0003.000000T0000Z-200515T1000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Adams IL-Brown IL-Pike IL-Knox MO-Lewis MO-Shelby MO-Marion MO-
Monroe MO-Ralls MO-Pike MO-Boone MO-Audrain MO-Moniteau MO-
Cole MO-Callaway MO-
Including the cities of Quincy, Mount Sterling, Pittsfield, 
Hannibal, Bowling Green, Columbia, Mexico, Jefferson City, 
and Fulton
446 AM CDT Fri May 15 2020

...FLASH FLOOD WATCH WILL EXPIRE AT 5 AM CDT EARLY THIS MORNING...

The Flash Flood Watch for portions of west central Illinois and
Missouri will expire at 5 AM CDT early this morning. The heavy
rainfall threat has ended. 

$$

TES

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
1149 PM CDT Wed May 13 2020

.UPDATE...
Issued at 927 PM CDT Wed May 13 2020

Isolated showers continue to move east across the area this
evening and do not expect much more until later tonight. Latest
surface analysis is showing that a warm front has moved into
southwest Missouri and northeast Arkansas, and this front will
continue to move north tonight. Still expect additional shower and
thunderstorm development late tonight into Thursday morning across
northern Missouri in west central Illinois as the low level jet
develops overnight. This will be the same area that will see the
least amount of capping and the most amount of low level moisture
convergence ahead of the warm front according to the latest runs
of the RAP. Still expect additional shower and thunderstorm
development on Thursday afternoon ahead of a cold front,
particular over the northern third of the CWA were there will be
the least amount of capping.

Britt

&&

.SHORT TERM...  (Through Late Thursday Night)
Issued at 305 PM CDT Wed May 13 2020

Warm front is currently near the MO/AR border and will continue to
slowly lift northward through the forecast area tonight. In the
meantime, elevated showers and isolated convection north of the
boundary will lift east northeast along and south of the I-70
corridor through early this evening. Could see another batch of
showers slide through the far southern portions of the forecast area
during this time period as well, due to a weakening MCS that is
currently over southwestern MO.

As for later tonight, numerous CAMs indicating MU CAPES between 500
to 1200 J/kg for portions of central/northeast MO and west central
IL between 06z and 12z Thursday along and north of the warm front.
This combined with decent shear and mid level lapse rates could help
to generate isolated strong to severe storms in this area with the
main threat being large hail.

Then will have a bit of a break in activity by mid morning on
Thursday before main cold front begins to slide south through the
forecast area. Ahead of cold front will continue to see increasing
low level moisture, steep lapse rates, effective bulk shear around
30kts, and decent instability with ML CAPES between 2000 and 3000
J/kg. So scattered strong to severe storms expected, especially
across portions of northeast/central MO and west central IL between
2 pm and 8 pm. The main threats will be large hail and damaging
winds, though an isolated tornado not out of the realm of
possibility, especially early on in the event. By late evening with
increasing convective inhibition, storms should weaken.

Otherwise, expect some breaks in the overcast on Thursday with warm
southerly winds and highs in the mid 70s to low 80s. Lows Thursday
night will be in the low to mid 60s.

Byrd

.LONG TERM...  (Friday through Next Wednesday)
Issued at 305 PM CDT Wed May 13 2020

By Friday, cold front will stall out across southern portions of
the forecast area. So will see several more rounds of showers and
storms Friday through Sunday, before boundary is finally pushed
south of region and surface ridge builds in. Dry weather expected
for the remainder of the forecast period. As for temperatures,
highs will remain in the 70s Friday through Sunday, then a bit
cooler Monday and Tuesday before temperatures warm back up to near
80 by Wednesday.

Byrd

&&

.AVIATION...  (For the 06z TAFs through 06z Thursday Night)
Issued at 1135 PM CDT Wed May 13 2020

IFR/LIFR ceilings will continue at KCOU through 09Z and at KUIN
and the St. Louis area terminals between 12-15Z before becoming
VFR by late morning. Some fog is expected at KUIN and the St.
Louis terminals early in the period. Showers and thunderstorms are
expected to move across northeast Missouri and west central
Illinois including KUIN between 10-14Z with some potential for heavy
rain and hail. While there will be the possibility for showers
and thunderstorms throughout the day at any of the terminals, the
best chance will be late in the afternoon and during the evening
as a cold front moves southeast across the area. Thunderstorms
will reduce conditions to MVFR/possible IFR in heavy rain with the
potential for hail and wind gusts over 35KTS.

SPECIFICS FOR KSTL:

IFR/LIFR ceilings and visibilities are expected through 15Z, with
MVFR ceilings rising to VFR by afternoon.  While there will be the
possibility for showers and thunderstorms during the late morning
and afternoon, best chance will be in the evening as a cold front
moves southeast into the terminal. Thunderstorms will reduce
conditions to MVFR/possible IFR in heavy rain with the potential
for hail and wind gusts over 35KTS.

Britt

&&

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

WFO LSX

Hazardous Weather Outlook
National Weather Service Saint Louis MO
316 PM CDT Wed May 13 2020

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-141200-
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-
316 PM CDT Wed May 13 2020

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

.DAY ONE...Tonight.

A few strong to severe thunderstorms are possible tonight, mainly
across central and northeast Missouri, as well as west central
Illinois, with hail as the main threat.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

There is a chance of thunderstorms across the area Thursday through
Sunday. Scattered severe thunderstorms are possible during the
afternoon and evening on Thursday. The main threats will be large
hail and damaging winds, though an isolated tornado possible early on
in the event.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed late tonight.

Byrd