000
FXUS63 KLSX 200955
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
455 AM CDT THU JUN 20 2013

.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 317 AM CDT THU JUN 20 2013

EARLY THIS MORNING...A RIDGE-RUNNER SHORTWAVE IS LOCATED JUST W OF
THE MS RIVER AND HAS BEEN KICKING UP CLOUDS AS A RESULT.  WEAKER
UPPER LEVEL DISTURBANCES EXIST FURTHER UPSTREAM IN NRN KS AND
NEBRASKA CLOSER TO THE CURRENT LOCATION OF THE UPPER LEVEL RIDGE
AXIS.  AT THE SFC...HI PRES CENTERED OVER THE ERN GREAT LAKES REGION
CONTINUES TO HAVE A WIDE INFLUENCE AND RESULTING IN A LIGHT SE FLOW.
MOSTLY CLEAR SKIES GRACE MUCH OF THE FA WITH TEMPS IN THE 60S.

UPPER LEVEL RIDGE OVER THE PLAINS WILL STRENGTHEN AND AMPLIFY TODAY
AND THEREFORE MAKE IT MUCH MORE DIFFICULT FOR ANY ADDITIONAL UPPER
LEVEL DISTURBANCES TO SUCCESSFULLY CROSS THRU.  ONE SUCH IS LOCATED
OVER IN ERN CO ATTM AND IS LOOKING INCREASINGLY LIKELY IT WILL BE
STUCK ON THE PLAINS AS A RESULT...WHICH WOULD DISCOUNT THE 00Z NAM
FCST WHICH HAS THIS FEATURE MAKING A RUN ON ERN MO LATE THIS AFTN.
CLOSER TO HOME...THE SHORTWAVE OVER ERN MO IS EXPECTED TO VERY
SLOWLY OOZE EWD TODAY...AND SHOULD STILL BE OVER SWRN IL THIS
AFTERNOON.  THE ENVIRONMENT WILL BE AGAIN GEARED TOWARDS ORDINARY
CELLS WITH WEAK SHEAR...NO CINH...AND MODEST CAPE GENERALLY LESS
THAN 1000 J/KG.  THE ONLY FOCUS TO REALLY KEY IN ON IS THE
RIDGE-RUNNER SHORTWAVE WHICH WILL PROVIDE SOME SOURCE OF LIFT AND
MIGHT BE ENOUGH SANS A DECENT SFC BOUNDARY TO KICK OFF ISOLD
SHRA/TSRA.  WILL NEED TO MONITOR FOR POTENTIAL OF /SUNRISE SURPRISE/
THRU MID MORNING BUT LOOKING DOUBTFUL.  AT THIS TIME...AND UNTIL A
BETTER SOURCE OF LIFT PRESENTS ITSELF...CAN ONLY JUSTIFY NO MORE
THAN SLIGHT CHCS IN THIS SETUP AND CENTERED ON THE AFTERNOON HOURS.

H850 TEMPS EXPECTED TO BE ABOUT 1-2C HIGHER THAN PERSISTENCE WITH
SIMILAR SUNSHINE AND MORE SLY ORIENTED WINDS...AND SHOULD TRANSLATE
TO ABOUT A 2-4F INCREASE FROM MAX TEMPS ON WEDNESDAY...OR MAX TEMPS
IN THE 85-90F RANGE.

TES

.LONG TERM...(TONIGHT THROUGH WEDNESDAY)
ISSUED AT 407 AM CDT THU JUN 20 2013

THERE MAY STILL BE ISOLATED CONVECTION EARLY THIS EVNG...MAINLY
ACROSS SERN MO AND SWRN IL ASSOCIATED WITH A WEAK VORT MAX MOVING
SLOWLY EWD INTO SRN IL. CONVECTION IS ALSO POSSIBLE LATE TGT INTO
FRI MRNG ACROSS NERN MO AND W CNTRL IL AS A SHORTWAVE OVER TOPS
THE UPPER LEVEL RIDGE WITH A WEAKENING MCS POSSIBLY DROPPING SEWD
INTO THIS AREA. ADDITIONAL CONVECTION IS POSSIBLE ACROSS THE REST
OF OUR FORECAST AREA AS THE ATMOSPHERE DESTABILIZES FRI AFTN ALONG
POSSIBLE OUTFLOW BOUNDARY FROM OVERNIGHT MCS. CONVECTIVE POTENTIAL
SHOULD END FRI NGT AS UPPER LEVEL RIDGE BUILDS NEWD INTO OUR AREA
WITH MOST OF THE CONVECTION REMAINING N OF OUR FORECAST AREA.
PERSISTENT SLY/SWLY SFC/LOW LEVEL FLOW WILL LEAD TO ABOVE NORMAL
TEMPERATURES FOR THE WEEKEND INTO THE NEXT WORK WEEK. HIGHS IN THE
UPPER 80S TO MIDDLE 90S SHOULD BE TYPICAL FOR SAT THROUGH WED. THE
UPPER LEVEL RIDGE SHOULD FLATTEN OVER OUR AREA AND RETROGRADE
FURTHER W AS AN UPPER LEVEL TROUGH MOVES EWD THROUGH THE NRN
PLAINS AND GREAT LAKES REGION WITH CONVECTION POSSIBLE ON WED AS A
COLD FRONT TRIES TO DROP SEWD INTO OUR AREA.

GKS

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 455 AM CDT THU JUN 20 2013

VFR CONDITIONS AND LIGHT SE-S SFC WNDS WILL PREVAIL THRU THE VALID
PERIOD. THERE IS A SLIGHT CHC OF TSRA...ESPECIALLY E OF THE MS
RIVER...BUT PROBS TOO LO TO MENTION AT THIS TIME.

SPECIFICS FOR KSTL...VFR AND LIGHT SE-S SFC WNDS THRU THE
PERIOD...SLIGHT CHANCE OF TSRA BUT PROB TOO LO TO MENTION IN TAF.

TES

&&

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

$$

WFO LSX