Area Forecast Discussion
Issued by NWS St. Louis, MO

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FXUS63 KLSX 300846
AFDLSX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
346 AM CDT SUN AUG 30 2015

.SHORT TERM:  (THROUGH LATE THIS AFTERNOON)
ISSUED AT 345 AM CDT SUN AUG 30 2015

WITH SOME BREAKS IN THE CLOUD COVER, LIGHT WINDS AND PLENTY OF LOW
LEVEL MOISTURE, FOG HAS DEVELOPED ALONG AND NORTH OF WEAKENING
FRONTAL BOUNDARY. DENSE FOG IS NOT WIDESPREAD ENOUGH IN OUR AREA TO
WARRANT A HEADLINE AT THIS TIME, THOUGH WILL HAVE AREAS OF FOG
MENTIONED IN FORECAST FOR THIS MORNING THROUGH 14Z. OTHERWISE,
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS STILL POSSIBLE OVER
SOUTH HALF OF FORECAST AREA DUE TO LINGERING WEAK FRONTAL BOUNDARY.
AS FOR HIGH TEMPS TODAY, LOW TO MID 80S EXPECTED DESPITE PARTLY TO
MOSTLY CLOUDY SKIES.

BYRD

.LONG TERM:  (TONIGHT THROUGH SATURDAY)
ISSUED AT 345 AM CDT SUN AUG 30 2015

SHOWERS AND THUNDERSTORMS THAT DO DEVELOP THIS AFTERNOON SHOULD
DIMINISH HEADING INTO THE EVENING HOURS, BUT WITH UPPER LEVEL SHEAR
AXIS LINGERING OVER SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS WILL
CONTINUE SLIGHT CHANCE POPS THROUGHOUT THE NIGHT OVER SOUTHEAST
SECTIONS OF THE CWA.

PRIMARY FORECAST QUESTION FOR MONDAY AND POSSIBLY EVEN INTO TUESDAY
IS WHAT IF ANY IMPACT THE AFOREMENTIONED SHEAR AXIS WILL HAVE ON THE
THUNDERSTORM THREAT IN OUR FA.  THERE IS GENERAL CONSENSUS THAT THIS
FEATURE WILL TAKE UP RESIDENCE FROM THE LOWER OHIO VALLEY INTO AR
DURING THE EARLY PART OF THE WORK WEEK...BUT THE EXACT LOCATION
DOES VARY FROM MODEL TO MODEL. MOS POPS FROM 00Z OPERATIONAL
NAM/GFS RUNS BOTH SUGGEST POPS AOB 10% OVER SE SECTIONS OF THE
CWA, ALTHOUGH 00Z OPERATIONAL ECMWF POPS ARE SLIGHTLY HIGHER THAN
THIS. FOR NOW HAVE DECIDED TO MAINTAIN A DRY FORECAST FOR
MONDAY (AND TUESDAY)...AND WILL LET DAY SHIFT TAKE ANOTHER LOOK
AT THIS THREAT.

MODELS REMAIN IN GOOD AGREEMENT THAT UPPER LEVEL RIDGE WILL BE
EXPANDING FROM THE PLAINS INTO THE MID-MISSISSIPPI VALLEY AS WE
HEAD THROUGH THE UPCOMING WEEK. THIS SHOULD SHIFT SHEAR AXIS SOUTH
OF THE FA WITH TIME...WHILE ANY UPPER LEVEL DYNAMICS WILL REMAIN
WELL NORTH AND NORTHWEST OF OUR AREA IN BAND OF WESTERLIES THAT
WILL STRETCH FROM THE PACIFIC NORTHWEST INTO SOUTH CENTRAL CANADA.
THIS SHOULD MEAN DRY AND TRANQUIL EARLY SEPTEMBER WEATHER FOR THE
CWA...WITH THE RETURN OF SUMMERTIME HEAT AND HUMIDITY. DEWPOINTS
HAVE ALREADY REBOUNDED TO SUMMERY LEVELS OVER THE PAST TWO
DAYS...AND IT APPEARS THAT TEMPERATURES WILL BE FOLLOWING THIS
TREND AS THE EASTWARD EXPANSION OF THE UPPER RIDGE PUSHES 850MB
TEMPS INTO THE 18-20C RANGE. THIS SHOULD EASILY SUPPORT HIGHS
AROUND THE 90 DEGREE MARK ACROSS THE ENTIRE FA IN THE TUESDAY-
SATURDAY TIME FRAME.

TRUETT

&&

.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

&&

.PRELIMINARY POINT TEMPS/POPS:
SAINT LOUIS     86  72  90  74 /  30  20  10  10
QUINCY          83  67  88  69 /  10  10   5   5
COLUMBIA        83  68  89  68 /  20  10  10   5
JEFFERSON CITY  85  67  89  68 /  20  20  10  10
SALEM           85  69  88  69 /  30  20  10  10
FARMINGTON      83  67  86  68 /  30  20  10  10

&&

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

$$

WFO LSX


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