000
FXUS63 KLSX 181740
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1240 PM CDT TUE JUN 18 2013

.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 255 AM CDT TUE JUN 18 2013

EARLY THIS MORNING...UPPER LEVEL RIDGE EXISTS OVER THE ERN ROCKIES
WITH A TROF OVER THE ERN CONUS...GIVING OUR AREA NW FLOW.  A
DECENTLY STRONG SHORTWAVE TROF IS DROPPING SE THRU ERN SD AND SWRN
MN AND KICKING OFF TSRA...WHILE SHORTWAVE THAT DUMPED A BUNCH OF
RAIN OVER PARTS OF OUR AREA ON MONDAY HAS SINCE EXITED AND IS OVER
THE LOWER OH VALLEY.  AT THE SFC...CALM WINDS ABOUND WITH VERY WEAK
PRES GRADIENT ACROSS OUR REGION TYPICAL OF SUMMERTIME.  A WEAK
BACKDOOR CDFNT FROM ERN IA THRU NRN IL TO CNTRL INDIANA IS MOVING
VERY SLOWLY SWWD.  PATCHY DENSE FOG HAS FORMED IN AREAS THAT HAVE
CLEARED OUT AND RECEIVED RAINFALL ON MONDAY.  TEMPS HAVE SLIPPED
INTO THE 60S.

A 25 VORT MAX ASSOCIATED WITH THE SHORTWAVE OVER SWRN MN IS EXPECTED
TO CONTINUE TO DROP SEWD AND TRACK THRU THE QUAD CITIES AREA EARLY
THIS AFTERNOON AND THEN INTO E-CNTRL IL BY EARLY EVENING...AND WILL
VERY CLOSELY MIRROR THE BACKDOOR SFC CDFNT AS IT DROPS INTO THAT
SAME REGION THIS AFTERNOON AND EFFECTIVELY EDGE OUR NERN FA AND
PROVIDES A FOCUS FOR TSRA DEVELOPMENT.  THE AIR IT WILL BE
INTERSECTING WILL BE VERY WEAKLY CAPPED...SUFFICIENTLY MOIST WITH
PWATS AROUND 1.25 INCHES...AND ADEQUATELY UNSTABLE WITH SBCAPES IN
THE 1000-2000 J/KG RANGE.  DEEP LAYER SHEAR OF 35-40KTS WILL PROMOTE
ORGANIZED DEVELOPMENT WITH A RELATIVELY BRIEF WINDOW IN THE MID-LATE
AFTN FOR STRONG-SEVERE POTENTIAL FOR WIND AND HAIL.  HAVE EDGED POPS
INTO CHANCE CATEGORY TOWARDS CNTRL IL AND KEPT MENTIONABLE POPS TO
THE NE EDGES OF THE STL METRO AREA AND MS RIVER...WITH THE BULK OF
THE TSRA ACTIVITY EXPECTED TO BE JUST TO THE NE.

H850 TEMPS BETWEEN 14-16C SHOULD GIVE US MAX TEMPS IN THE BALLPARK
THAT MOS IS GIVING US FOR MOST SITES...ALTHOUGH MOS LOOKS A BIT TOO
COOL AT KUIN AND ADJUSTED UP A COUPLE DEGS.

TES

.LONG TERM...(TONIGHT THROUGH MONDAY)
ISSUED AT 329 AM CDT TUE JUN 18 2013

MAY STILL HAVE CONVECTION THIS EVNG...MAINLY ACROSS SWRN IL AHEAD OF
SHORTWAVE DROPPING SEWD THROUGH IL AND ALONG BACKDOOR TYPE COLD
FRONT DROPPING SWD THROUGH IL.  THIS CONVECTION SHOULD DISSIPATE OR
SHIFT SE OF OUR FORECAST AREA BY LATE TGT. WILL HAVE BELOW NORMAL
LOW TEMPERATURES TGT DUE TO WEAK LOW LEVEL CAA...A CLEARING
SKY...LIGHT SFC WINDS...AND RELATIVELY LOW SFC DEW POINTS AS A SFC
RIDGE OVER THE GREAT LAKES NOSES INTO NERN MO AND W CNTRL IL. THE
DRY PERIOD SHOULD CONTINUE ON WED AND WED EVNG WITH THE NEXT
CHANCE OF RAIN BEGINNING LATE WED NGT ACROSS NERN AND CNTRL MO AS
A SWLY LOW LEVEL JET BRINGS LOW LEVEL WAA AND INCREASING LOW LEVEL
MOISTURE INTO THIS AREA AHEAD OF AN APPROACHING SHORTWAVE. THE
PRECIPITATION SHOULD SPREAD ACROSS MOST OF OUR FORECAST AREA ON
THU. MOST OF THIS PRECIPITATION SHOULD SHIFT E-SE OF OUR AREA THU
NGT AS THE SHORTWAVE MOVES E-SE OF OUR REGION...AND AS AN UPPER
LEVEL RIDGE OVER THE SRN PLAINS TRIES TO BUILD NEWD INTO MO. THIS
UPPER LEVEL RIDGE WILL CONTINUE TO BUILD INTO OUR AREA AND THIS
COUPLED WITH PERSISTENT S/SWLY SFC/LOW LEVEL WINDS WILL LEAD TO A
TYPICAL SUMMER WEATHER PATTERN INTO THE WEEKEND WITH ABOVE NORMAL
TEMPERATURES AND HIGH HUMIDITIES. ALTHOUGH THE BEST CHANCE OF
CONVECTION SHOULD BE ACROSS THE NRN PLAINS AND GREAT LAKES REGION...
WILL INCLUDE LOW CHANCE POPS ACROSS NERN MO AND W CNTRL IL AS MCS
ACTIVITY COULD DROP SEWD INTO THIS AREA. COULD ALSO NOT RULE OUT
ISOLATED LATE AFTN AND EARLY EVNG CONVECTION MAINLY DUE TO DAYTIME
HEATING AND ANY OUTFLOW BOUNDARIES THAT MANAGE TO MAKE IT INTO OUR
AREA.

GKS

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1230 PM CDT TUE JUN 18 2013

ANOTHER COMPLEX FCST WITH MULTIPLE SFC BOUNDARIES AND UPPER LVL
SUPPORT THAT WILL HELP TSRA DEVELOPMENT THIS AFTN. A CDFNT OVER
CNTL IL WILL SLOWLY MOVE SWD THIS AFTN AND BE A FOCUS FOR TSRA.
THESE TSRA MAY IMPACT UIN/SUS/CPS THIS AFTN. A SFC TROF EXTENDS
FROM THIS FNT WWD INTO CNTL MO...CURRENTLY JUST S OF COU. BELIEVE
COU WILL BE BETWEEN THESE TO FOCI AND SHUD REMAIN DRY.
HOWEVER...THERE IS SOME UNCERTAINTY WITH THIS SOLN AS THIS TROF
MAY MOVE NWD SLIGHTLY THIS AFTN. OTHERWISE...BELIEVE ENUF DRY AIR
WILL MOVE IN TONIGHT AT ALL SITES...EXCEPT FOR COU...TO PREVENT FG
DEVELOPMENT.

FOR TOMORROW...EXPECT VFR CU WITH LIGHT ELY TO SELY WINDS. IF FG
DOES DEVELOP TNGT AT COU...A BRIEF PERIOD OF MVFR CIGS AT COU WILL
BE POSSIBLE.

SPECIFICS FOR KSTL...TSRA MAY IMPACT THE TERMINAL THIS AFTERNOON
INTO THE EVENING AS A CDFNT DROPS SWD TWD THE AREA.
OTHERWISE...EXPECT VFR CONDITIONS THRU TNGT WITH WINDS BECOMING
LIGHT. LIGHT ELY TO SELY WINDS FOR TMW WITH VFR CU.

TILLY

&&

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

$$

WFO LSX