Area Forecast Discussion
Issued by NWS St. Louis, MO

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000
FXUS63 KLSX 291742
AFDLSX

AREA FORECAST DISCUSSION...UPDATED AVIATION
NATIONAL WEATHER SERVICE ST LOUIS MO
1242 PM CDT SAT AUG 29 2015

.SHORT TERM:  (THROUGH LATE THIS AFTERNOON)
ISSUED AT 325 AM CDT SAT AUG 29 2015

WIDELY SCATTERED SHOWERS CONTINUE TO DEVELOP AND MOVE NORTHEAST
ACROSS THE FORECAST AREA EARLY THIS MORNING AHEAD OF THE COLD FRONT.
BECAUSE OF LIMITED MOISTURE, COVERAGE OF ACTIVITY TO REMAIN
ISOLATED/SCATTERED THROUGH THE DAY TODAY AS COLD FRONT WEAKENS WITH
TIME AS IT MOVES INTO THE FORECAST AREA. SOME WEAK INSTABILITY WITH
THIS SYSTEM, BUT FOR NOW HAVE SHOWERS WITH ISOLATED THUNDERSTORM
MENTION. AS FOR HIGH TEMPS, DESPITE CLOUD COVER, TEMPERATURES TO
CONTINUE WITH A SLOW WARMING TREND WITH HIGHS IN THE UPPER 70S TO
MID 80S TODAY.

BYRD

.LONG TERM:  (TONIGHT THROUGH FRIDAY)
ISSUED AT 325 AM CDT SAT AUG 29 2015

FOR THE LAST SEVERAL DAYS MODEL SOLUTIONS HAVE BECOME INCREASINGLY
FUZZY HEADING INTO THE LAST FEW DAYS OF AUGUST...AND TONIGHTS 00Z
RUNS REMAIN RATHER UNCLEAR. THERE IS GENERAL AGREEMENT OF BROAD
UPPER AIR TROF FORMING OVER THE AREA AS INITIAL SHORTWAVE AND
SEVERAL WEAKER DISTURBANCES WORK SOUTHEAST AND ATTEMPT TO PHASE
WITH WEAK CIRCULATION CENTER OVER THE LOWER MISSISSIPPI VALLEY...WITH
SOME SOLUTIONS ALSO HINTING AT WEAK MID LEVEL CIRCULATION
DEVELOPING OVER S MO AND/OR N AR. MEANWHILE...FRONTAL BOUNDARY
WILL BE WEAKENING WITH TIME AS IT ENCOUNTERS PERSISTENT SURFACE
RIDGE OVER THE EASTERN CONUS...WITH 00Z RUNS FOLLOWING YESTERDAYS
12Z SOLUTIONS THAT THIS BOUNDARY WILL BECOME STATIONARY OVER
NORTHWEST SECTIONS OF THE FA BY THIS EVENING.

THINK GOING FORECASTS FOR TONIGHT STILL LOOK PRETTY GOOD WITH A LOW
CHANCE OF SHOWERS AND THUNDERSTORMS OVER MOST OF THE CWA THIS
EVENING AHEAD OF SHORTWAVE...GRADUALLY BECOMING FOCUSED OVER THE
SOUTHEAST HALF OF THE CWA AFTER MIDNIGHT.  WITH GNARLY LOOKING UA
PROGS SUGGESTING SOME BIT OF ENERGY HANGING OVER SOUTHERN SECTIONS
OF THE AREA ON SUNDAY SOME LOW POPS WILL CONTINUE HERE...BUT HAVE
ALSO EXPANDED THIS THREAT BACK NORTH (TO NEAR A PARIS-MOUNT STERLING
LINE) DURING THE AFTERNOON BASED ON FORECAST SOUNDINGS THAT
INDICATE AFTERNOON INSTABILITY WITH LITTLE OR NO CIN. I DIDN`T
ACTUALLY TAKE POPS BACK TO STALLED BOUNDARY AS MODELS DO SUGGEST
SOME INCREASE OF MID LEVEL HEIGHTS (AS WELL AS INCREASED CIN) OVER
FAR NORTHERN SECTIONS OF THE CWA.

ITS POSSIBLE THAT THIS PESKY UPPER LEVEL "REMNANT" WILL BE A PLAYER
FOR CONVECTIVE POTENTIAL ON MONDAY AS WELL.  HOWEVER...AT THIS POINT
WILL MAINTAIN A DRY FORECAST AS MODEL SOLUTIONS DIVERGE QUITE A BIT
WITH THE PLACEMENT OF THIS FEATURE BY 60 HRS.  SUNDAYS CONVECTION
TRENDS SHOULD ALSO BE A GOOD CLUE ON HOW TO HANDLE ANY THREAT WITH
THIS FEATURE BY MONDAY.

WHILE SOME VESTIGE OF THIS FEATURE ACTUALLY HANGS AROUND THROUGH
MIDWEEK...MEDIUM RANGE GUIDANCE SUGGESTS THAT UPPER LEVEL RIDGING
WILL BECOME INCREASINGLY DOMINATE OVER THE CENTRAL CONUS AS STRONG
UPPER LEVEL LOW TAKES SHAPE OVER WESTERN CANADA. THIS PATTERN
WOULD SUPPORT GOING FORECAST TRENDS THAT INDICATE DRY AND WARM
EARLY SEPTEMBER WEATHER FOR MOST OF NEXT WEEK.

TRUETT

&&

.AVIATION:  (FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1222 PM CDT SAT AUG 29 2015

STILL EXPECTING WIDELY SCT SHRA/TSRA TO DEVELOP ACROSS THE REGION
THIS AFTN. WITH THE FNT FORECAST TO WASHOUT ACROSS THE
AREA...TIMING POSS MVFR CIGS AND EXTENT OF CLD COVER WILL BE
DIFFICULT. WITH QUESTIONS OF CLOUD COVER...UNCERTAINTY REMAINS
REGARDING FG DEVELOPMENT TONIGHT. HAVE ADDED MVFR VSBYS TO
UIN...BUT SLIGHTLY LESSER CHANCES EXIST AT COU. SLY TO SWLY WINDS
EXPECTED AGAIN ON SUN. LOW MVFR TO POSSIBLY IFR CIGS ARE EXPECTED
AGAIN TONIGHT. EXACTLY WHERE THE SERN EDGE OF THIS CLOUD DECK WILL
BE IS DIFFICULT TO DETERMINE...BUT IS CURRENTLY EXPECTED TO BE
JUST N/NW OF COU/UIN.

SPECIFICS FOR KSTL: WIDELY SCT TSRA STILL EXPECTED THIS AFTN.
OTHERWISE...EXPECT VFR CONDITIONS WITH SLY TO SWLY WINDS.

TILLY

&&

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

$$

WFO LSX


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