000
FXUS63 KLSX 191005
AFDLSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
505 AM CDT WED JUN 19 2013
.SHORT TERM...(THROUGH LATE THIS AFTERNOON)
ISSUED AT 303 AM CDT WED JUN 19 2013
EARLY THIS MORNING...UPPER LEVEL RIDGE EXISTS OVER THE HI PLAINS
WITH NW FLOW DOWNSTREAM FROM IT OVER OUR REGION. A RIDGE-RUNNER
SHORTWAVE IS OVER WRN KS AND NEBRASKA GENERATING CLUSTERS OF TSRA
WITH A WEAKER UPPER LEVEL DISTURBANCE OVER SERN KS HELPING TO
MAINTAIN SOME TSRA ACTIVITY NEAR ICT. AT THE SFC...AN ILL-DEFINED
BOUNDARY SNAKES FROM SRN INDIANA THRU SRN IL AND SRN MO AND CURVES
NWD NEAR THE KS-MO BORDER. TO THE N OF THIS BOUNDARY...A LIGHT NE
SFC FLOW HAS BUILT IN. SFC TEMPS HAVE FALLEN INTO THE 60S WITH A
FEW SPOTS THREATENING TO DIP INTO THE UPR 50S...A REAL TREAT FOR
LATE JUNE.
IT SEEMS WE CANNOT ESCAPE DISCUSSING RAIN CHCS EACH DAY...AND THIS
DAY SEEMS TO BE NO EXCEPTION.
NW UPPER LEVEL FLOW IS EXPECTED TO WEAKEN TODAY...FLATTEN OVERHEAD
WITH RISING H5 HEIGHTS. THIS WILL TEND TO NOT RESULT IN MUCH PUSH
FOR SFC FRONTS...AND SO WILL PROBABLY SEE THE WEAK SFC BOUNDARY
LINGER NEAR ITS PRESENT POSITION THRU THE DAY...THOUGH QUESTIONABLE
IN WHAT SHAPE IT WILL BE IN BY MID-LATE AFTERNOON. IN ANY EVENT...
ALL MODELS SHOW RELATIVELY MODEST SBCAPES OF 500-1000 J/KG WITH ZERO
CINH DURING MID-LATE THIS AFTERNOON OVER AN AREA THAT NORMALLY
INCLINES TOWARDS PCPN MORE THAN OTHER AREAS GIVEN ITS INTANGIBLES
SUCH AS TOPOGRAPHY...IN SERN MO AND SRN IL. GFS OVERDOES PCPN
DEVELOPMENT WITH SFC DWPTS OF 70F...BUT EVEN WRF MODEL AND ITS MORE
REALISTIC MID 60S DWPTS SHOULD RESULT IN ISOLD SHRA/TSRA. HAVE
INTRODUCED SLGT CHC POPS OVER MUCH OF THE SRN AND ERN FA...INCLUDING
THE STL METRO AREA...FOR MID-LATE AFTERNOON FOR WHAT SHOULD BE
SHORT-LIVED SINGLE CELL CONVECTION WITH THE VERY WEAK DEEP LAYER
SHEAR AND MODEST CAPE. RIDGE-RUNNER SHORTWAVE IS EXPECTED TO STILL
BE TOO FAR W TO HAVE ANY IMPACT BY EARLY THIS EVENING.
H850 TEMPS AND COMPARISON TO PERSISTENCE SUPPORT MAX TEMPS NEAR OR
JUST ABOVE THE WARMEST MOS VALUES...OR MID 80S FOR MOST LOCATIONS
WITH UPR 80S EXPECTED FOR STL METRO.
TES
.LONG TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 400 AM CDT WED JUN 19 2013
MAY STILL HAVE ISOLATED SHOWERS AND STORMS INTO THE EARLY EVNG
ACROSS PARTS OF SERN MO AND SWRN IL. A WEAK SHORTWAVE WILL MOVE EWD
INTO IA AND WRN MO LATE TGT. THIS COUPLED WITH A SWLY LOW LEVEL JET
BRINGING LOW LEVEL WAA AND INCREASING LOW LEVEL MOISTURE INTO NWRN
MO MAY LEAD TO SOME CONVECTION ACROSS PARTS OF NERN AND CNTRL MO
LATE TGT INTO EARLY THU MRNG. THE BETTER THREAT OF CONVECTION
SHOULD BE ON THU AS LOW LEVEL MOISTURE INCREASES OVER THE ENTIRE
AREA...ALTHOUGH THE SHORTWAVE SHOULD WEAKEN AS IT GETS FURTHER E.
NAM MODEL APPEARS A LITTLE DEFICIENT IN ITS QPF ON THU. THE UPPER
LEVEL RIDGE OVER THE SRN PLAINS WILL BUILD SLOWLY NEWD INTO MO THU
NGT AND FRI. THE NAM MODEL IS A LITTLE LOWER WITH ITS MID-UPPER
LEVEL HEIGHTS COMPARED TO THE GFS AS IT CONTINUES TO FORECAST
SHORTWAVES MOVING THROUGH OUR AREA AND JUST N OF OUR AREA. MAY
STILL HAVE CONVECTION ACROSS MAINLY NERN MO AND W CNTRL IL DURING
THIS PERIOD. BY FRI NGT AND SAT THE UPPER LEVEL RIDGE SHOULD BUILD
OVER OUR REGION WITH MOST OF THE CONVECTION REMAINING N OF OUR FORECAST
AREA. WITH THE UPPER LEVEL RIDGE OVER OUR AREA...PERSISTENT
S-SWLY SFC/LOW LEVEL WINDS...AND PLENTY OF DAYTIME SUNSHINE A PROLONGED
PERIOD OF ABOVE NORMAL TEMPERATURES IS EXPECTED FOR THE WEEKEND
INTO NEXT WEEK. THE GFS MODEL FLATTENS THE UPPER LEVEL RIDGE ON
MON AND TUE WHICH MAY LEAD TO A BETTER CHANCE OF CONVECTION...
ESPECIALLY OVER THE NRN PORTION OF OUR FORECAST AREA.
GKS
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 505 AM CDT WED JUN 19 2013
VFR CONDITIONS AND LIGHT EASTERLY SFC WNDS WILL PREVAIL AT THE TAF
SITES THRU THE VALID TAF PERIOD. ISOLD SHRA/TSRA ARE POSSIBLE MID-
LATE AFTERNOON OVER PARTS OF E-CNTRL AND SE MO AS WELL AS SRN IL
BUT PROBS TOO LOW TO MENTION IN TAFS AT THIS TIME.
SPECIFICS FOR KSTL...VFR CONDITIONS AND LIGHT EASTERLY SFC WNDS
THRU THE VALID PERIOD...VERY LO PROBABILITY OF SHRA/TSRA MID-LATE
AFTERNOON BUT NOT ENOUGH TO MENTION IN FCST AT THIS TIME.
TES
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
