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000
FXUS63 KIND 180441
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1241 AM EDT SAT MAY 18 2013

.UPDATE...

THE AVIATION SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 220 PM EDT FRI MAY 17 2013

A WEAK AREA OF LOW PRESSURE OVER SOUTHEAST MISSOURI WILL DRIFT INTO
THE OHIO VALLEY TONIGHT AND ACROSS SOUTHERN INDIANA ON SATURDAY.
THIS WILL BRING CHANCES FOR SHOWERS AND THUNDERSTORMS TO THE
SOUTHERN PARTS OF STATE TONIGHT AND SATURDAY.

A WEAK RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE AREA ON
SUNDAY...HOWEVER WITH A CONTINUED WARM AND HUMID AIR MASS IN PLACE
AN ISOLATED SHOWER OR STORM CANNOT BE RULED OUT ON SUNDAY.

EARLY NEXT WEEK A LARGE TROUGH CARVES OUT OVER THE WESTERN HALF OF
THE COUNTRY INTO THE WEEKEND WHICH WILL BRING WARMER AIR FOR MUCH OF
NEXT WEEK ALONG WITH ANOTHER COUPLE DAYS OF STORMY WEATHER MONDAY
INTO MID WEEK.

&&

.NEAR TERM /REST OF TONIGHT/...
ISSUED AT 1007 PM EDT FRI MAY 17 2013

ONLY SCATTERED SHOWERS REMAIN ACROSS THE FORECAST AREA AS PREVIOUS
CONVECTION HAS MODIFIED THE ATMOSPHERE. THERE REMAINS SOME LINGERING
INSTABILITY ACROSS THE NORTHWEST FORECAST AREA...BUT RECENT TRENDS
SHOW CONVECTION THERE IS WEAKENING TOO.

WEAK UPPER TROUGH WILL CONTINUE TO GENERATE SOME SCATTERED SHOWERS
TONIGHT. WATER VAPOR SATELLITE SHOWS SOME UPPER ENERGY ACROSS
ILLINOIS THAT WILL MOVE INTO THE AREA LATER TONIGHT AS WELL. THUS
FEEL THAT LOW POPS SHOULD CONTINUE THROUGH THE NIGHT. HOWEVER HAVE
REMOVED THUNDER MENTION WITH LOSS OF MOST INSTABILITY.

CLOUDS WILL REMAIN ACROSS MUCH OF THE AREA OVERNIGHT WITH THE UPPER
TROUGH...HOWEVER THERE WILL BE SOME BREAKS AS CAN BE CURRENTLY SEEN
IN SATELLITE IMAGERY. THESE BREAKS SHOULD ALLOW SOME PATCHY FOG TO
FORM DUE TO THE RAIN TODAY. THUS HAVE ADDED PATCHY FOG TO THE
FORECAST.

ONLY MADE MINOR TWEAKS TO TEMPERATURES.

&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
ISSUED AT 220 PM EDT FRI MAY 17 2013

MAIN FORECAST CHALLENGE WILL BE POPS

GFS AND NAM SUGGEST A WEAK UPPER LOW PUSHING THROUGH THE OHIO
VALLEY AND SOUTHERN INDIANA SATURDAY AND EXITING THE AREA BY LATE
SATURDAY AFTERNOON. FORECAST SOUNDINGS INDICATE THAT BEST DRYING
DOES NOT ARRIVE UNTIL TOWARD 00Z. TIME HEIGHTS MEANWHILE KEEP A
VERY MOIST AIR MASS IN PLACE ACROSS THE AREA ALONG WITH WEAK
SUBSIDENCE ALOFT. LOWER LEVEL Q VECTORS ALSO INDICATE DIVERGENCE.
THUS ONLY WEAK FORCING ASSOCIATED WITH THE SHORT WAVE AND DAYTIME
HEATING WILL BE OUR TRIGGERING MECHANISMS. BEST FORCING IN THIS
REGARD WILL BE FOUND ACROSS THE SOUTHERN PARTS OF THE FORECAST
AREA THUS WILL ONLY RAISE POPS ACROSS THOSE SPOTS DURING THE DAY
ON SATURDAY. FARTHER NORTH WILL TREND POPS AT OR BELOW MAVMOS AND
ALSO TREND POPS LOWER AS THE LATE AFTERNOON PROGRESSES AS THE
UPPER LOW DEPARTS. WILL TREND HIGHS AT OR BELOW MAVMOS GIVEN THE
EXPECTED CLOUDS AND POSSIBLE PRECIPITATION.

FORECAST SOUNDINGS ON SATURDAY NIGHT AND SUNDAY SHOW MUCH DRIER
AIR ARRIVING ACROSS CENTRAL INDIANA AS DEW POINTS FALL
DRAMATICALLY THROUGH THE COLUMN. THE PREVIOUSLY MENTIONED UPPER
LOW ALSO CONTINUES TO EXIT THE AREA AS WEAK RIDGING BUILDS ACROSS
THE AREA FOR SUNDAY.THUS WILL TREND TOWARD A DRY FORECAST FOR
SATURDAY NIGHT. ON SUNDAY FORECAST SOUNDING ARE NOW HINTING AT A
GOOD CAP IN PLACE AS 700MB TEMPS APPROACH 9-10C BY 00Z MONDAY. THUS
CONFIDENCE FOR A DRY FORECAST ON SUNDAY HAS GROWN. AS FOR TEMPS...A
BLEND WILL WORK NICELY.

GFS AND NAM CONTINUE TO SUGGEST STRONG RIDGING ALOFT OVER THE
REGION ON SUNDAY NIGHT AND MONDAY. MEANWHILE 850MB TEMPS CONTINUE
A SLOW CLIMB TOWARD 18C-20C BY 18Z MONDAY. FORECAST SOUNDINGS SHOW
CONVECTIVE TEMPS IN THE LOWER 90S WHICH MAY BE TOO WARM TO TRIGGER
ANY INITIATION. THUS WITHOUT STRONG DYNAMICS AVAILABLE A WARM
SUNDAY NIGHT AND A SUMMER LIKE MONDAY WILL BE EXPECTED. WILL TREND
BOTH LOWS AND HIGHS AT OR ABOVE MAVMOS.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
ISSUED AT 220 PM EDT FRI MAY 17 2013

ENSEMBLES ARE COMING INTO BETTER AGREEMENT TODAY WITH RESPECT TO THE
EVOLVING WEATHER PATTERN NEXT WEEK. MAIN FEATURE DURING THIS PERIOD
WILL BE AN UPPER LOW THAT IS EXPECTED TO MOVE SLOWLY EAST FROM THE
PLAINS...CROSSING THE LOCAL AREA AROUND THE MIDDLE OF NEXT WEEK.
ENSEMBLES SUGGEST THE BEST CHANCES FOR PRECIPITATION WILL BE ON
TUESDAY AND WEDNESDAY...SO WILL GO WITH HIGHER POPS AT THOSE TIMES.
SOME OF THE SLOWER MEMBERS LINGER A PRECIPITATION THREAT INTO
THURSDAY...SO WILL GO WITH CHANCE POPS AT THAT TIME.

MOST THE ENSEMBLES NOW AGREE THAT THE UPPER TROUGH SHOULD BE EAST OF
THE AREA BY NEXT FRIDAY...WITH A STRONG UPPER RIDGE BUILDING INTO
THE PLAINS AND MIDWEST. WILL GO DRY FOR NEXT FRIDAY.

&&

.AVIATION /DISCUSSION FOR THE 18/06Z TAFS/...
ISSUED AT 1241 AM EDT SAT MAY 18 2013

UPPER TROUGH WILL MOVE EAST ACROSS SOUTHERN INDIANA TONIGHT AND
SATURDAY MORNING. WOULD NOT RULE OUT ISOLATED SHOWERS OVERNIGHT AND
ISOLATED TO SCATTERED THUNDERSTORMS AFTER 15Z AS NORTHWEST FLOW
ALOFT DRAWS THE QUASI-STATIONARY SURFACE FRONT SOUTH TO NEAR A
BMG-HUF LINE BY 12Z AND SOUTH OF THE TERMINALS BY 00Z...AND MODELS
SHOW PLENTY OF INSTABILITY. HOWEVER...NO MAJOR FORCING...SO WILL GO
DRY UNTIL 15Z AND THEN VCTS FROM 15Z-20Z AT LAF AND HUF AND 22Z AT
IND AND BMG.

STILL COULD SEE SOME MVFR OR WORSE FOG AND OR CEILINGS AFTER
08Z...BUT IF THICK AC CAN HANG AROUND...IT COULD PREVENT THAT.
CONFIDENCE MEDIUM TO LOW ON MVFR OR WORSE CONDITIONS 08Z-13Z.

LIGHT TO CALM EAST AND SOUTHEAST WINDS TONIGHT SHOULD BE MOSTLY EAST
ON SATURDAY TO THE NORTH OF THE FRONT ESPECIALLY AT IND AND LAF. HUF
AND BMG MAY NOT SEE A WIND SHIFT UNTIL AFTERNOON. AT ANY
RATE...WINDS SHOULD BE LESS THAN 10 KNOTS DURING THE DAYTIME AND
LIGHT TO CALM AT NIGHT.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SYNOPSIS...PUMA
NEAR TERM...50
SHORT TERM...PUMA
LONG TERM....JAS
AVIATION...MK

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