Special Weather Statement, NWS St. Louis, MO

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
659 PM CDT Sun May 20 2018

.SHORT TERM...  (Through Late Monday Afternoon)
Issued at 228 PM CDT Sun May 20 2018

Still a lot of uncertainty on how to handle precip chances over the
next 24 hours. Main system to our southwest to begin lifting north
northeast through forecast area tonight. Will see additional rounds
of showers and storms develop and move through depending on how fast
the atmosphere recovers from this mornings storms. So exact timing
and placement of activity still hard to pin down, so just kept high
chance pops for the area. As for chances of severe storms, again
depends on recovery of atmosphere. As of 19z, CAPE values are back
above 1000 J/kg over southern half of Missouri, but lower and capped
further north.

By midday Monday, main cold front to exit forecast area with some
lingering activity diminishing by 00z Tuesday.

Lows tonight will be mild, in the low to mid 60s with highs on
Monday in the upper 70s to mid 80s.

Byrd

.LONG TERM...  (Monday Night through Next Sunday)
Issued at 228 PM CDT Sun May 20 2018

By Monday night, system finally exits and will have dry conditions
through at least mid week as surface ridge builds in. Some
differences in timing, strength and placement with next several
systems among the extended models. So kept slight/low chance pops
from time to time through rest of extended period.

As for temperatures, to remain 5 to 10 degrees above normal through
the extended period.

Byrd

&&

.AVIATION...  (For the 00z TAFs through 00z Monday Evening)
Issued at 556 PM CDT Sun May 20 2018

Main concerns tonight into Monday will center around thunderstorms
approaching from the southwest. Outside the cluster of storms,
concerns are limited with just mid/high clouds streaming in well
ahead of the activity. Winds are generally light and/or variably.

Thunderstorms chances will increase after 00z, affecting KCOU
first, then spreading north and east overnight. Cigs will likely
drop to mvfr along the front with any vsby issues being confined
to those directly impacted by thunderstorms. Storm intensity will
likely wave through the late night hours, but cannot rule out a
few embedded storms.

The front finally pushes through from west to east Monday
afternoon. We may see a few afternoon storms pop along and east of
the Mississippi River until the front clear. Otherwise expect
improving conditions through the afternoon hour from west to east.

SPECIFICS FOR KSTL:

We continue to watch thunderstorm development over southwest and
central Missouri. Ahead of the activity VFR conditions will
continue with scattered/broken mid to high clouds and variable
winds.

Storms approach KSTL around midnight. Ceilings will remain VFR a
majority of the time. MVFR cigs could impact the site should
thunderstorms survive this far east. Will account for lower cigs
in amendments should they be necessary later this evening.

Overall improvement is in the forecast Monday, as the front drive
east of the area. Some signals show a few showers lingering
through morning with the possibility of scattered afternoon
storms. These should primarily stay east of KSTL with clouds
breaking with a clearing trend through the afternoon.

Maples

&&

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

WFO LSX

Hazardous Weather Outlook
National Weather Service Saint Louis MO
330 PM CDT Sun May 20 2018

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-211200-
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-
330 PM CDT Sun May 20 2018

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

.DAY ONE...Tonight

Isolated severe thunderstorms will be possible across the area
through this evening. Large hail and damaging winds will be the
primary threats.

.DAYS TWO THROUGH SEVEN...Monday through Saturday

There is a chance of thunderstorms Monday, then there are chances
of thunderstorms Wednesday through Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed through this evening.

Byrd

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
742 PM CDT SUN MAY 20 2018

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

0725 PM     TSTM WND DMG     TIPTON                  38.66N 92.78W
05/20/2018                   MONITEAU           MO   PUBLIC

            NUMEROUS TREE LIMBS AND A COUPLE OF TREES
            BLOWN DOWN AROUND TOWN.

&&

MAB

Special Weather Statement
National Weather Service St Louis MO
835 PM CDT SUN MAY 20 2018

MOZ034-041-042-050-210215-
Audrain MO-Monroe MO-Boone MO-Callaway MO-
835 PM CDT SUN MAY 20 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN BOONE...WESTERN
AUDRAIN...NORTH CENTRAL CALLAWAY AND SOUTHWESTERN MONROE COUNTIES
UNTIL 915 PM CDT...

At 835 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Sturgeon to near Hallsville to near Murry.
Movement was northeast at 35 mph.

Wind gusts up to 50 mph will be possible with these storms.

Locations impacted include...
Mexico, Centralia, Hallsville, Sturgeon, Madison, Harrisburg,
Holliday, Vandiver, Hatton and Thompson.

This also includes  Finger Lakes State Park and Union Covered Bridge
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 3925 9239 3925 9231 3935 9231 3951 9218
      3936 9183 3911 9178 3896 9207 3914 9211
      3904 9229 3914 9248
TIME...MOT...LOC 0135Z 225DEG 32KT 3920 9237 3912 9218 3897 9214

TES

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