Special Weather Statement, NWS St. Louis, MO

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
644 PM CDT Sat May 27 2017

.SHORT TERM...  (Through Late Sunday Afternoon)
Issued at 313 PM CDT Sat May 27 2017

Severe weather watches will continue across central and southeast
MO and southwest IL into the evening hours. Supercells were
occuring across parts of southeast MO with bow echoes in central
and southwest MO. These bow echoes may consolidate into a larger
squall line late this afternoon. Once this squall line clears our
forecast area by late evening we should just have some lingering
showers and a few storms. Most of the convection should shift
south of our forecast area by midnight. Will still have a chance
of showers and storms on Sunday until an upper level trough
centered over the northern Plains and a cold front shift east-
southeast of our forecast area. Any severe weather threat should
be southeast of the forecast area on Sunday.

GKS

.LONG TERM...  (Sunday Night through Next Saturday)
Issued at 313 PM CDT Sat May 27 2017

Cooler conditions can be expected Sunday night due to a clear sky
and lower surface dew points. Another cold front will drop
southeastward through our area Monday afternoon and evening, but
little if any precipitation is expected with this front. A better
chance of showers may occur on Tuesday as a northwest flow
shortwave moves through our area. A surface ridge will build into
the region from the northern Plains on Wednesday shunting better
moisture and any precipitation threat south of our forecast area.
As this surface ridge shifts east of the region Thursday return
southerly flow on the backside of the ridge should lead to
increasing moisture and the potential for convection Thursday
night and Friday.

GKS

&&

.AVIATION...  (For the 00z TAFs through 00z Sunday Evening)
Issued at 550 PM CDT Sat May 27 2017

It looks like one more thunderstorm will pass through the COU
area early this evening per radar trends, with thunderstorms
moving southeast of the St Louis metro area early this evening. It
appears that the convection will shift south of the taf sites
later this evening. The models continue to indicate stratus clouds
and light fog late tonight and early Sunday morning as surface
winds become light with surface dew points still high. For now
will just forecast MVFR cigs and vsbys late tonight and early
Sunday morning, although a brief period of IFR conditions is
possible. Surface wind will become northwesterly and strengthen
Sunday morning after the passage of a cold front with any fog
dissipating and cloud ceilings slowly rising. Could not rule out
some post frontal showers on Sunday with an upper level
disturbance moving through the area, but will leave precipitation
out of the tafs for now.

SPECIFICS FOR KSTL: Thunderstorms will move southeast of the STL
area early this evening. It appears that the convection will
shift south of the St Louis metro area later this evening. The
models continue to indicate stratus clouds and light fog late
tonight and early Sunday morning as surface winds become light
with surface dew points still high. For now will just forecast
MVFR cigs and vsbys late tonight and early Sunday morning,
although a brief period of IFR conditions is possible. Surface
wind will become northwesterly and strengthen Sunday morning after
the passage of a cold front with any fog dissipating and cloud
ceilings slowly rising. Could not rule out some post frontal
showers on Sunday with an upper level disturbance moving through
the area, but will leave precipitation out of the taf for now.

GKS

&&

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

WFO LSX

Hazardous Weather Outlook
National Weather Service Saint Louis MO
354 PM CDT Sat May 27 2017

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-281115-
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-
354 PM CDT Sat May 27 2017

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

.DAY ONE...Tonight

Severe weather this evening, particularly across east central and
southeast Missouri and southwest Illinois. Damaging winds to 80
mph, golfball or larger size hail, and a few tornadoes will be
possible.

.DAYS TWO THROUGH SEVEN...Sunday through Friday

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will be needed into the evening hours. Spotters
are encouraged to report any severe weather, if observed, to the
National Weather Service.

GKS

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
756 PM CDT SAT MAY 27 2017

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

0507 PM     TSTM WND DMG     FREDERICKTOWN           37.57N 90.30W
05/27/2017                   MADISON            MO   LAW ENFORCEMENT

            ROOF PARTIALLY BLOWN OFF BAREFOOT FIREWORKS
            NEAR FREDERICKTOWN.

&&

KD

Special Weather Statement
National Weather Service St Louis MO
756 PM CDT SAT MAY 27 2017

MOZ084-085-280145-
Madison MO-Iron MO-
756 PM CDT SAT MAY 27 2017

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN IRON AND SOUTHERN
MADISON COUNTIES IN SOUTHEASTERN MISSOURI UNTIL 845 PM CDT...

At 756 PM CDT, Doppler radar was tracking a strong thunderstorm over
Annapolis, moving east at 40 mph.

Nickel size hail will be possible with this storm.

Locations impacted include...
Annapolis, Marquand, Buckhorn, Saco, Des Arc, Sabula and Vulcan.

A severe thunderstorm watch remains in effect until 200 AM CDT for
southeastern Missouri.

LAT...LON 3745 9076 3743 9014 3731 9014 3732 9055
      3727 9055 3727 9074
TIME...MOT...LOC 0056Z 276DEG 36KT 3736 9071

Glass