Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 300513
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1213 AM CDT SUN AUG 30 2015

.UPDATE:
ISSUED AT 838 PM CDT SAT AUG 29 2015

NO BIG CHANGES TO THE FORECAST. VERY ISOLATED SHOWERS CONTINUE TO
PERCOLATE ACROSS THE CENTER OF THE CWA NEAR A SHEAR AXIS/WEAK
FRONT. THIS WILL PROBABLY CONTINUE MOST OF THE NIGHT AS A WEAK LOW
LEVEL JET DEVELOPS AND AIDS THE LIFT OVERHEAD.

CVKING

&&

.SHORT TERM:  (THROUGH LATE TONIGHT)
ISSUED AT 333 PM CDT SAT AUG 29 2015

SHOWERS HAVE MOVED OUT OF THE CWA FOR THE MOMENT AS WATER VAPOR
IMAGERY IS CURRENTLY SHOWING THAT A WEAK UPPER LOW IS MOVING EAST
ACROSS SOUTHEAST MISSOURI. THERE IS ALSO A SHORTWAVE TROUGH
EXTENDING FROM THE GREAT LAKES INTO FAR NORTHEAST MISSOURI AND
A VORT MAX OVER SOUTHWEST MISSOURI THAT IS MOVING EASTWARD. THE
RAP SHOWS SOME WEAK ASCENT ALONG THE TROUGH AXIS AS IT MOVES EAST
SOUTHEAST THIS EVENING ACROSS NORTHEAST MISSOURI AND WEST CENTRAL
ILLINOIS WHILE THERE IS ALSO SOME INCREASED ASCENT ACROSS AREAS
SOUTH OF I-70 ASSOCIATED WITH THE VORT MAX. IN ADDITION...THE RAP
IS SHOWING SOME INCREASE IN LOW LEVEL MOISTURE CONVERGENCE
ASSOCIATED WITH THE VORT MAX. WILL GO WITH A CHANCE OF SHOWERS AND
THUNDERSTORMS OVER THE SOUTHEASTERN HALF OF THE CWA THIS
EVENING...WITH LESSENING CHANCES OVERNIGHT AS THE MOISTURE
CONVERGENCE WEAKENS AND MOVES OFF TO THE EAST.

BRITT

.LONG TERM:  (SUNDAY THROUGH NEXT SATURDAY)
ISSUED AT 333 PM CDT SAT AUG 29 2015

(SUNDAY THROUGH TUESDAY)

THE UPPER LEVEL TROUGH AXIS WILL BE SLOW TO MOVE OUT OF THE AREA AS
AN UPPER LEVEL RIDGE BUILDS OVER IT ACROSS THE UPPER MIDWEST ON
SUNDAY AND MONDAY. THIS WILL KEEP THE UPPER LEVEL TROUGH OVER THE
AREA AT LEAST THROUGH SUNDAY WHICH WILL SUPPLY SOME LIFT OVER THE
AREA THROUGH THE DAY. RUNS OF THE CAMS SUGGEST THAT CONVECTIVE
COVERAGE WILL BE SCATTERED DURING THE DAY SO HAVE UPPED POPS TO 30
PERCENT IN MOST AREAS. GFS AND NAM BEGIN TO BECOME MORE UNCERTAIN
ON LOCATION OF TROUGH AXIS BY MONDAY...SO WENT WITH DRY FORECAST
THOUGH IT IS POSSIBLE THAT THE TROUGH AXIS COULD WELL END UP IN
SOUTHERN MISSOURI AND BRING THE SOUTHERN CWA A SLIGHT CHANCE OF
THUNDERSTORMS. WILL ALSO KEEP TUESDAY DRY FOR NOW...THOUGH THE NAM
WOULD BRING A WEAK SHORTWAVE TROUGH ACROSS THE AREA DURING THE DAY
THAT MAY BEAR WATCHING.

WENT ON THE WARM SIDE OF GUIDANCE THROUGH THE PERIOD AS WE WILL BE
MIXING DOWN AIR FROM THE 800-850MB LAYER...PARTICULARLY ON MONDAY
AND TUESDAY WHICH HAS TEMPERATURES AROUND +20C WHICH FAVORS
TEMPERATURES GOING BACK ABOVE NORMAL.

(WEDNESDAY THROUGH NEXT SATURDAY)

AREA WILL BE MAINLY DRY LATE WEEK INTO NEXT WEEKEND AS UPPER
RIDGE AXIS THAT EXTENDS FROM THE CENTRAL PLAINS INTO THE UPPER
MIDWEST ON THURSDAY WILL SHIFT OVER MISSOURI AND ILLINOIS BY
SATURDAY. CONSEQUENTLY...SURFACE RIDGE WILL LINGER OVER MISSOURI
AND ILLINOIS THROUGH THE MEDIUM RANGE PERIOD. TEMPERATURES WILL BE
AT OR SLIGHTLY ABOVE NORMAL AS WE GO INTO THE HOLIDAY WEEKEND AS
850MB TEMPERATURES REMAIN CLOSE TO +20C.

BRITT

&&

.AVIATION:  (FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1208 AM CDT SUN AUG 30 2015

SPECIFICS FOR KCOU, KUIN: MVFR/IFR STRATUS DECK APPEARS LIKELY TO
AFFECT KUIN AND POSSIBLY KCOU DURING THE FIRST 0-6 HOURS,
ALTHOUGH KCOU SHOULD REMAIN ON THE SOUTHEASTERN EDGE AND MAY BE
LESS AFFECTED. CONDITIONS SHOULD IMPROVE TO VFR BY 30/15Z. WINDS
WILL REMAIN LIGHT AND SOUTHEASTERLY TO SOUTHERLY THROUGH THE PD.

SPECIFICS FOR KSTL, KSUS, KCPS: ISOLATED SH/TS ARE POSSIBLE
HOWEVER COVERAGE APPEARS GREATER FARTHER SOUTH AND EAST. LIGHT FOG
IS POSSIBLE HOWEVER THE DVLPG STRATUS DECK SHOULD REMAIN NORTH AND
WEST OF THE TERMINALS. WINDS WILL REMAIN LIGHT AND SOUTHEASTERLY
TO SOUTHERLY THROUGH THE PD.

KANOFSKY

&&

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

$$

WFO LSX


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