000
FXUS63 KLSX 190804
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
304 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...(WEDNESDAY THROUGH NEXT TUESDAY)
ISSUED AT 243 PM CDT TUE JUN 18 2013

WEDNESDAY THROUGH FRIDAY...
DRY AND SEASONAL WEATHER IS EXPECTED FOR WEDNESDAY WITH LIGHT WINDS
FROM THE EAST AS THE SURFACE RIDGE DOMINATES THE REGION. WEDNESDAY
NIGHT A 50KT LOW LEVEL JET WILL INTENSIFY ACROSS THE PLAINS AND
INTERACT WITH A SHORTWAVE TOPPING THE UPPER LEVEL RIDGE. THE GFS
DEPICTS A DEEPER SHORTWAVE WHEN COMPARED TO THE NAM AND THEREFORE
DEVELOPS SHOWERS AND THUNDERSTORMS ACROSS CENTRAL NEBRASKA AND EAST
CENTRAL KANSAS. THE QUESTION IS HOW FAR EAST WILL THE CONVECTION
TRAVEL WEDNESDAY NIGHT INTO THURSDAY MORNING AS THE LOW LEVEL JET
VEERS. FOR NOW HAVE MAINTAINED SLIGHT CHANCE POPS ACROSS CENTRAL AND
NORTHEAST MISSOURI LATE WEDNESDAY NIGHT...BUT FEEL THE BETTER
CHANCES WILL REMAIN WEST OF THE CWA.

MEANWHILE...AT THE SURFACE A WARM FRONT WILL BE PUSHING NORTHEAST
ACROSS THE REGION ON THURSDAY. INSTABILITY WILL INCREASE THROUGHOUT
THE DAY BRINGING A GREATER CHANCE FOR THUNDERSTORMS TO THE AREA.

THE WARM FRONT SHOULD MOVE NORTHEAST OF THE REGION AS THE UPPER
RIDGE BUILDS OVER THE CWA. DEEP MIXING AND A SOUTHERLY SURFACE WIND
WILL ALLOW TEMPERATURES TO RISE ABOVE NORMAL INTO THE LOWER 90S.

SATURDAY THROUGH TUESDAY...
SOUTHWEST TO NORTHEAST ORIENTATED UPPER LEVEL RIDGE TO DOMINATE THE
CENTER OF THE NATION THIS WEEKEND...WITH ABOVE NORMAL TEMPERATURES
AND LIMITED CHANCES OF PRECIPITATION. THE PATTERN WILL BEGIN TO
BREAK DOWN BY EARLY NEXT WEEK AS THE FLOW BECOMES MORE ZONAL AND THE
UPPER LEVEL RIDGE REESTABLISHES ITSELF TO OUR WEST.

GRANA

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1010 PM CDT TUE JUN 18 2013

VFR CONDITIONS ARE EXPECTED AT MOST TAF SITES FOR THE MAJORITY OF
THE TAF PD WITH LIGHT WINDS BECOMING SELY TOMORROW. THE EXCEPTION
MAY BE AT KCOU LATER TONIGHT IF THE CIRRUS CLOUDS CLEAR OUT BEFORE
A DRIER AIR MASS ARRIVES AT LOW LEVELS. THE RESULTING RADIATIONAL
COOLING CONDITIONS COULD PRODUCE A FEW HOURS OF MVFR FOG OR
STRATUS BEFORE CONDITIONS IMPROVE BY MID-MORNING.

SPECIFICS FOR KSTL...VFR THROUGH THE PD WITH LIGHT WINDS BECOMING
SELY TOMORROW.

KANOFSKY

&&

.PRELIMINARY POINT TEMPS/POPS...
SAINT LOUIS     87  66  90  69 /  20  10  20  10
QUINCY          83  64  87  68 /   5  10  30  20
COLUMBIA        86  65  88  68 /  10  20  30  10
JEFFERSON CITY  86  66  88  69 /  10  10  30  10
SALEM           84  63  88  68 /  10  10  10  10
FARMINGTON      85  62  88  66 /  20  20  20  10

&&

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

$$

WFO LSX