Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 290516
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1216 AM CDT SAT AUG 29 2015

.SHORT TERM:  (THROUGH LATE TONIGHT)
ISSUED AT 315 PM CDT FRI AUG 28 2015

WATER VAPOR IMAGERY SHOWS THAT A SHORTWAVE TROUGH IS MOVING SLOWLY
EAST ACROSS MISSOURI AT THIS HOUR.  LATEST RUNS OF THE RAP SUGGEST
THAT IT WILL TAKE ALL EVENING FOR THIS FIRST SHORTWAVE TO REACH
HALFWAY ACROSS THE CWA WHILE A SECOND SHORTWAVE WILL ENTER WESTERN
MISSOURI BEHIND IT LATER TONIGHT.  LOW LEVEL MOISTURE CONVERGENCE
WILL INCREASE ACROSS EASTERN MISSOURI BY LATER THIS EVENING AS LOW
LEVEL JET VEERS AND INCREASES IN SPEED SLIGHTLY.  THIS SHOULD CAUSE
AN INCREASE IN COVERAGE IN SCATTERED SHOWERS AND THUNDERSTORMS BY
LATE EVENING AND OVERNIGHT OVER THE REGION BECAUSE OF THE FORCING
FROM THE SHORTWAVES AND THE MOISTURE CONVERGENCE.  THE 1KM
REFLECTIVITY FROM THE CAMS DEPICTS THIS PRETTY WELL.

MOS LOWS TONIGHT LOOK REASONABLE GIVEN THE INCREASING DEWPOINTS
AHEAD OF THE COLD FRONT CURRENTLY OVER THE CENTRAL PLAINS.

BRITT

.LONG TERM:  (SATURDAY THROUGH NEXT FRIDAY)
ISSUED AT 316 PM CDT FRI AUG 28 2015

AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS CAN BE EXPECTED ON
SATURDAY AND SATURDAY EVENING AS AN UPPER LEVEL TROUGH MOVES
SLOWLY SOUTHEASTWARD THROUGH OUR AREA. IT NOW APPEARS THAT THE
COLD FRONT WILL ONLY MAKE IT INTO NORTHEAST MO AND WEST CENTRAL IL
BEFORE GRADUALLY DISSIPATING. ONLY SLIGHT COOLING IS EXPECTED
ACROSS NORTHEAST MO AND WEST CENTRAL IL SATURDAY AND SATURDAY
NIGHT WITH THE REST OF THE AREA SLIGHTLY WARMER AND MORE HUMID
DESPITE THE CLOUD COVER ON SATURDAY WITH MAINLY A WEAK SOUTHERLY
FLOW. ALTHOUGH THE CHANCE OF PRECIPITATION WILL LESSEN BY LATE
SATURDAY NIGHT AND SUNDAY...THERE MAY STILL BE AT LEAST ISOLATED
SHOWERS/STORMS ACROSS MAINLY SOUTHEAST MO AND SOUTHWEST IL AS THE
WEAKENING UPPER LEVEL TROUGH...SHEAR AXIS MOVES ONLY SLOWLY
SOUTHEASTWARD. A WAMER PERIOD OF WEATHER IS FORECAST FOR THE NEXT
WORK WEEK DUE TO PERSISTENT SOUTHERLY SURFACE/LOW LEVEL FLOW WITH
THE SURFACE/850 MB RIDGE EAST/SOUTHEAST OF OUR AREA...AND AT
LEAST UPPER LEVEL RIDGING ACROSS NORTHWEST MO. WILL KEEP THE
REMAINDER OF THE FORECAST DRY FOR NOW...ALTHOUGH COULD NOT RULE
OUT A FEW SHOWERS/STORMS MAINLY DURING THE AFTERNOON AND EARLY
EVENING HOURS AS THE MODELS CONTINUE TO DEPICT SOME WEAK MID-UPPER
LEVEL TROUGHING...SHEAR AXIS ACROSS MAINLY SOUTHEAST MO AND
SOUTHWEST IL.

GKS

&&

.AVIATION:  (FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 1208 AM CDT SAT AUG 29 2015

SPECIFICS FOR KCOU, KUIN: RAIN SHOWERS WILL CONTINUE TO INCREASE
IN COVERAGE OVERNIGHT AS A COUPLE OF UPPER LEVEL DISTURBANCES
APPROACH THE REGION. THUNDERSTORMS ARE POSSIBLE AT KUIN DURING THE
AFTERNOON, BUT CURRENT MODELS SUGGEST THE PRECIPITATION WOULD BE
EAST OF KCOU BY THEN. WINDS WILL REMAIN SOUTHEASTERLY TO
SOUTHERLY, THEN BECOME LGT/VAR INVOF A WEAK COLD FRONT.

SPECIFICS FOR KSTL, KSUS, KCPS: THE INCOMING SHIFT NOTICED SOME
LIGHT RAIN ON THEIR COMMUTE TO THE OFFICE IN WELDON SPRING, SO IT
LOOKS LIKE AT LEAST SOME OF THOSE WEAKER ECHOES ON RADAR ARE
PRODUCING RAINFALL. ADDED VCSH TO KSUS AND KSTL FOR THE NEXT FEW
HOURS BASED ON THE CURRENT RADAR TRENDS. SHOWERS SHOULD BECOME
MORE WIDESPREAD WITH TIME AS A COUPLE OF UPPER LEVEL DISTURBANCES
MOVE ACROSS THE AREA. THUNDERSTORMS ARE POSSIBLE DURING THE
AFTERNOON. WINDS WILL REMAIN SOUTHEASTERLY TO SOUTHERLY, THEN
BECOME LGT/VAR INVOF A WEAK COLD FRONT.

KANOFSKY

&&

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

$$

WFO LSX



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