Special Weather Statement, NWS St. Louis, MO

Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
718 PM CDT Mon Jun 11 2018

.SHORT TERM...  (Through Late Tuesday Afternoon)
Issued at 249 PM CDT Mon Jun 11 2018

Concerns through the Tuesday afternoon will pertain to the
thunderstorms potential this afternoon, then again during the day
Tuesday.

Current analysis depicts a nearly stationary boundary stretching
from near the IA/MO border eastward through IL/IN region. This
originated a bit further south early this morning, before
meandering northward this afternoon. This is likely to become the
focus for initial convection early this afternoon and into the
evening, where moisture convergence is maximized and instability
gradients reside. Expecting a narrow corridor more focused
development.

Given precipitable water values in excess of 1.5 inches through
the region, along with relatively weak flow, locally heavy rain
with localized ponding is a concern. However, confidence is low
that similar areas affected by yesterday's training rainfall will
be impacted again today. Best potential remains a bit further
north into central IL, where highest rainfall totals were
received. Therefore, held off on any watch products at this time
and will keep an eye on this evening's development.

Further south of the this boundary, sct/isolated convection is
possible and will be more diurnally driven. Expect activity to be
shorter lived and wane after sunset. Good instability with
MUCAPEs around 3k J/kg or better may give rise to a strong storm
with any severe potential being isolated.

Well-organized convection is expected to remain well west of the
forecast area through western MO, originating along a cold front
in the central plains. There is the potential for an MCS to
materialize and dive almost due south. The northern extent of the
line may reach central Missouri late tonight, but given better
support to the west, expecting this to weaken as it spreads out to
the east.

The cold front pushes into the bi-state area during the day
Tuesday. Pending convection may impact tomorrow's thunderstorms
with any residual cloud cover. Front should be positioned through
eastern Missouri by early afternoon with better potential for
development east of the Mississippi River Tuesday afternoon.

Maples

.LONG TERM...  (Tuesday Night through Next Monday)
Issued at 249 PM CDT Mon Jun 11 2018

Tuesday's frontal boundary will continue to slowly slip south and
east through Wednesday. Scattered showers and thunderstorms are
possible along and ahead of the front. As is common for this time
of year, forward progression of the front could slow or stall.
Expect southern sections of Missouri and Illinois to have a better
potential from afternoon storms before the boundary clears the
area.

Surface high pressure builds in through the middle of the week and
will effectively limit rain potential. An upper ridge is still
well-advertised to develop from the mid to late week period. This
is likely to keep the main storm track outside the area. Main
story late this week into the weekend will be the building heat
with temperatures that may climb well into the 90s.

Maples

&&

.AVIATION...  (For the 00z TAFs through 00z Tuesday Evening)
Issued at 718 PM CDT Mon Jun 11 2018

VFR conditions, outside of thunderstorms, will prevail at the TAF
sites thru the valid period. A period of storms in vicinity is
expected with ongoing convection this evening at STL metro sites
with a quiet period before another round moves in late tonight
associated with developing MCS northwest of MO. Have timed this
for UIN and COU but am holding off on STL metro until we can
observe for a few more hours with most models severely weakening
this overnight. Otherwise, tried to time the next round with
afternoon heating with the best chances at STL metro sites where
they will be nearest a weak front sliding thru. Otherwise, look
for light south winds to gradually veer thru the valid period to
NW behind the front.

SPECIFICS FOR KSTL: Gust front and whether anything will form is
main focus next few hours. Will time MCS well to the NW later this
evening if it holds.

TES

&&

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

WFO LSX

Hazardous Weather Outlook
National Weather Service Saint Louis MO
420 PM CDT Mon Jun 11 2018

ILZ058>060-064-065-069-070-074-079-095>102-MOZ018-019-026-027-
034>036-041-042-047>052-059>065-072>075-084-085-099-121200-
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-
420 PM CDT Mon Jun 11 2018

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

.DAY ONE...Tonight

There is a chance for thunderstorms. Isolated strong to severe
storms are possible. The primary threats are large hail and
damaging wind gusts along with locally heavy rainfall.

.DAYS TWO THROUGH SEVEN...Tuesday through Sunday

The chance for thunderstorms will continue for parts of the
forecast area until Friday.

Isolated strong to severe storms are possible Tuesday and Tuesday
evening across southeast Missouri and southwest Illinois. The
primary threats are large hail and damaging wind gusts.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed tonight. Spotters are encouraged
to report any severe weather, if observed, to the National
Weather Service.

TES

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
644 PM CDT MON JUN 11 2018

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

0638 PM     HAIL             GODFREY                 38.97N 90.19W
06/11/2018  M0.88 INCH       MADISON            IL   AMATEUR RADIO

            3 SEPARATE REPORTS OF NICKEL SIZE HAIL
            RELAYED VIA AMATEUR RADIO.

&&

MAPLES

Special Weather Statement
National Weather Service St Louis MO
702 PM CDT MON JUN 11 2018

ILZ064-100-120030-
Bond IL-Madison IL-
702 PM CDT MON JUN 11 2018

...SIGNIFICANT WEATHER ADVISORY FOR BOND COUNTY IN SOUTH CENTRAL
ILLINOIS AND NORTHEASTERN MADISON COUNTIES IN SOUTHWESTERN ILLINOIS
UNTIL 730 PM CDT...

At 702 PM CDT, Doppler radar was tracking a strong thunderstorm over
Alhambra, moving southeast at 15 mph.

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

Locations impacted include...
Glen Carbon, Highland, Greenville, Worden, Marine, Livingston,
Pocahontas, Alhambra, Sorento, Beaver Creek, Reno, Hamel, Pierron,
Grantfork, New Douglas, Williamson, Old Ripley, Fruit, Kaufman and
Dudleyville.

This includes the following highways...
 Interstate 70 in Illinois between exits 21 and 45.
 Interstate 55 in Illinois between exits 23 and 37.

LAT...LON 3876 8992 3898 8985 3901 8938 3874 8936
TIME...MOT...LOC 0002Z 295DEG 15KT 3887 8970

Tilly

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
711 PM CDT MON JUN 11 2018

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

0704 PM     HAIL             1 N EDWARDSVILLE        38.81N 89.96W
06/11/2018  E0.75 INCH       MADISON            IL   AMATEUR RADIO

            REPORT OF DIME SIZE HAIL RELAYED VIA AMATEUR
            RADIO.

&&

AE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ST LOUIS MO
717 PM CDT MON JUN 11 2018

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

0716 PM     TSTM WND GST     3 ENE DUDLEYVILLE       38.83N 89.37W
06/11/2018  M40 MPH          BOND               IL   AWOS

&&

TILLY

Special Weather Statement
National Weather Service St Louis MO
733 PM CDT MON JUN 11 2018

ILZ065-070-120115-
Marion IL-Fayette IL-
733 PM CDT MON JUN 11 2018

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN MARION AND FAYETTE
COUNTIES UNTIL 815 PM CDT...

At 733 PM CDT, Doppler radar was tracking strong thunderstorms near
Vandalia, moving east at 25 mph.

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

Locations impacted include...
Vandalia, St. Elmo, Kinmundy, Brownstown, Patoka, Farina, Shobonier,
Avena, La Clede, Pittsburg, Shafter, St. Peter, Vernon, Loogootee,
St. James, St. Paul and Hagerstown.

This includes the following highways...
 Interstate 70 in Illinois between exits 61 and 76.
 Interstate 57 in Illinois between exits 127 and 135.

LAT...LON 3874 8870 3873 8914 3874 8914 3874 8925
      3906 8925 3905 8880 3891 8881 3891 8869
TIME...MOT...LOC 0033Z 273DEG 23KT 3893 8915

Tilly