Special Weather Statement, NWS St. Louis, MO

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
658 PM CDT Thu Aug 16 2018

.SHORT TERM...  (Through Late Friday Afternoon)
Issued at 323 PM CDT Thu Aug 16 2018

The main focus in the short term will be the severe weather
potential over the area this evening into the overnight hours.  A
cold front over northeast and central Missouri will slowly move east
this evening into the overnight hours through the forecast area. The
front will run into an environment of surface based CAPE values in
the range of 2500J/kg to 3000J/kg. There will be 30 to 40 knots of
bulk shear along with low and mid level lapse rates around 7C/km
over the area. A few strong to severe thunderstorms are possible
this evening into the overnight hours over the forecast area.  The
primary hazards this evening into the overnight hours will be large
hail and damaging winds. The cold front will move to parts of
southeast Missouri and southwest Illinois by Friday morning and
remain over the area through Friday afternoon. Temperatures will be
just a couple of degrees above normal for the morning low and
daytime high on Friday.

Kelly

.LONG TERM...  (Friday Night through Next Thursday)
Issued at 323 PM CDT Thu Aug 16 2018

A cold front over southeast Missouri and southwest Illinois will
push into the Ohio Valley on Friday night. An area of high pressure
will slide into the region providing dry weather and seasonal
temperatures to the area on Saturday into Sunday. The high pressure
system will slide to the east by Sunday afternoon. A cold front will
into the area by late Sunday night with scattered showers and
thunderstorms possible over central and southeast Missouri. The
front will move through the area on Monday with the best chances for
showers and thunderstorms through the forecast area. The front will
move out of the area by Tuesday morning. An upper level disturbance
behind the front will provide just enough lift for isolated showers
and thunderstorms on Tuesday over the area. A area of high pressure
will slide east into the area on Wednesday and provide dry weather
to the area. Temperatures near seasonal values this weekend before
dropping to around 5 degrees below average through the middle of
next week.

Kelly

&&

.AVIATION...  (For the 00z TAFs through 00z Friday Evening)
Issued at 636 PM CDT Thu Aug 16 2018

VFR conditions will continue over the next couple hours through
much of the area. The primary concern will be the developing
complex of thunderstorms over eastern Kansas and western Missouri.

These storms will expand and spread eastward through the evening
and into the overnight hours from west to east. Some of the storms
could be locally strong with heavy rain, gusty winds and frequent
lightning. Most of this will track from KCOU around 02z to KCPS
just after 10z. Some showers and isolated storms could linger
behind the through early morning. Expect mainly VFR/MVFR
conditions with brief, localized dips below MVFR with any direct
hit from thunderstorms. VFR conditions are expected into Frida.

SPECIFICS FOR KSTL:

Main concern will be developing thunderstorms out to the west.
Until then, VFR conditions are likely to extend into this evening.

The prime time for showers and thunderstorms will be just after
midnight to around 09z or so. Some of the storms could become
strong with heavy downpours, gusty winds and lightning. Being
nocturnal convection, it is hard to tell just how long the
intensity in the storms will hold. Any direct impact could result
in conditions lower than MVFR.

Expect VFR conditions heading into Friday with slight chances for
afternoon precip. Otherwise, most activity slides off to the
southeast of the TAF site.

Maples

&&

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

WFO LSX

Hazardous Weather Outlook
National Weather Service Saint Louis MO
348 PM CDT Thu Aug 16 2018

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-171215-
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-
348 PM CDT Thu Aug 16 2018

This hazardous weather outlook is for portions of eastern and
central Missouri as well as west central and southwest Illinois.

.DAY ONE...Tonight

Thunderstorms are expected through tonight. A few of these storms
may become strong enough to produce damaging winds or large hail.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday

There is a chance for thunderstorms over parts of the area
Friday and Friday evening, and then again Sunday night into
Tuesday.

.SPOTTER INFORMATION STATEMENT...

Spotters are encouraged to report any severe weather to the
National Weather Service.

Britt

Special Weather Statement
National Weather Service St Louis MO
900 PM CDT THU AUG 16 2018

MOZ034-035-042-170245-
Audrain MO-Monroe MO-Ralls MO-
900 PM CDT THU AUG 16 2018

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHWESTERN RALLS...NORTHEASTERN
AUDRAIN AND SOUTHEASTERN MONROE COUNTIES UNTIL 945 PM CDT...

At 900 PM CDT, Doppler radar was tracking a strong thunderstorm 8
miles south of Paris, moving east at 35 mph.

Nickel size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Vandalia, Santa Fe, Perry, Laddonia and Farber.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

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 3946 9210 3949 9146 3945 9145 3945 9146
      3918 9142 3929 9211
TIME...MOT...LOC 0200Z 274DEG 31KT 3936 9201

TES

Special Weather Statement
National Weather Service St Louis MO
1041 PM CDT THU AUG 16 2018

ILZ058-059-099-170415-
Macoupin IL-Greene IL-Jersey IL-
1041 PM CDT THU AUG 16 2018

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL GREENE...NORTHWESTERN
MACOUPIN AND NORTHEASTERN JERSEY COUNTIES UNTIL 1115 PM CDT...

At 1041 PM CDT, Doppler radar was tracking a strong thunderstorm near
Greenfield, moving east at 25 mph.

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

Locations impacted include...
Carrollton, Greenfield, Palmyra, Kemper, Kane, Medora, Wrights,
Chesterfield, Hettick, Rockbridge, Belltown, Berdan and Woody.

LAT...LON 3920 9051 3940 9045 3946 8999 3916 9002
TIME...MOT...LOC 0341Z 270DEG 21KT 3933 9030

Tilly