000
FXUS63 KIND 172205
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
605 PM EDT FRI MAY 17 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 /TONIGHT/...

ISSUED AT 220 PM EDT FRI MAY 17 2013

SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS A FRONTAL BOUNDARY
STRETCHING SOUTH OF LAF AND FRANKFORT TO SOUTH OF MUNCIE. EASTERLY
WINDS WERE FOUND NORTH OF THE FRONT WHILE SOUTHERLY WINDS AND A
MORE MOIST AIR MASS WAS FOUND ACROSS THE SOUTHERN PARTS OF THE
FORECAST AREA. RADAR SHOWS SCATTERED TSRA DEVELOPING AS CONVECTIVE
TEMPS ARE BEING REACHED. WATER VAPOR IMAGERY SHOWS A SHORT WAVE
OVER WESTERN TENNESSEE...SLOWLY EDGING EASTWARD.

DUE TO DAYTIME HEATING AND THE APPROACHING SHORT WAVE...SCATTERED
CONVECTION IS EXPECTED TO CONTINUE INTO THE EVENING HOURS.
FORECAST SOUNDINGS CONTINUE TO INDICATE FAVORABLE STEEP LAPSE
RATES THIS EVENING CAPE FALLING FROM OVER 1000 J/KG THIS AFTERNOON
T LESS THAN 100 J/KG BY 06Z. 305K GFS ISENTROPIC SURFACE CONTINUES
TO INDICATE BROAD...WEAK LIFT ACROSS THE AREA AHEAD OF THE
LOW...HOWEVER A VERY MOIST AIR MASS REMAINS ACROSS THE AREA
THROUGH SUNDAY WITH MIXING RATIOS IN EXCESS OF 7 G/KG. THUS WILL
CONTINUE WITH POPS AT OR ABOVE MAVMOS...HIGHEST SOUTH OF THE
PREVIOUSLY MENTIONED FRONTAL BOUNDARY EARLY DURING THE EVENING
HOURS...THEN WANE THE POPS THROUGH THE EVENING AS INSTABILITY AND
FORCING IS LOST. GIVEN THE WARM...MOIST AIR MASS IN PLACE ALONG
WITH PLENTIFUL CLOUDS WILL TREND LOWS AT OR ABOVE
GUIDANCE...PERHAPS NEAR PERSISTENCE.

&&

.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 180000Z TAF ISSUANCE/...
ISSUED AT 605 PM EDT FRI MAY 17 2013

ELONGATED UPPER WAVE ON THE FRONT SIDE OF AN UPPER TROUGH NEAR THE
INDIANA AND ILLINOIS BORDER WILL CONTINUE TO LIFT NORTHEAST AND
SHOULD BE NORTH OF LAF BY ISSUANCE TIME. WIDESPREAD BAND OF
THUNDERSTORMS WAS OCCURING JUST NORTH OF THE WAVE AND SHOULD REMAIN
THAT WAY...SO SHOULD NOT PRESENT A PROBLEM FOR ANY OF THE TAF SITES
AFTER 00Z. HOWEVER...ANOTHER WAVE WAS LIFTING NORTHEAST NEAR THE
OHIO RIVER AND SHOULD MOVE SOUTHEASTERN AND EAST CENTRAL INDIANA
OVERNIGHT. THIS FEATURE WAS CURRENTLY HELPING TO PRODUCE ISOLATED TO
SCATTERED SHOWERS ACROSS SOUTH CENTRAL INDIANA. WOULD NOT RULE A
SHOWER OR THUNDERSTORM AT IND AND BMG WITH THIS FEATURE...BUT
CHANCES APPEAR TOO LOW TO GO WITH ANYTHING MORE THAN VCSH OR VCTS
THROUGH JUST BEYOND SUNSET. BY 02Z...ALREADY MARGINAL INSTABILITY
SHOULD BE ABOUT SPENT. FOR THE REST OF THE NIGHT...WITH THE LOW
LEVELS OF THE ATMOSPHERE MOIST...AND LIGHT WINDS...SHOULD SEE AT
LEAST MVFR FOG AND OR CEILINGS AFTER 08Z...IMPROVING BACK TO VFR
AFTER 13Z SATURDAY. WOULD NOT RULE OUT A FEW MORE STORMS ON SATURDAY
AFTER 15Z AS THE UPPER TROUGH MOVES ACROSS...AND INSTABILITY ONCE
AGAIN INCREASES. IN ADDITION...FRONT JUST TO THE NORTH OF LAF COULD
SETTLE BACK SOUTH OVERNIGHT AS THE UPPER FLOW BECOMES NORTHWEST.
WINDS WILL CONTINUE TO 10 KNOTS OR LESS EXCEPT PERHAPS IN THE
THUNDERSTORMS. WINDS WILL SHIFT FROM SOUTHEAST TO EAST AFTER 06Z AS
THE FRONT SETTLES SOUTH OF THE TERMINALS.

&&

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

$$

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

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