000
FXUS63 KIND 192245
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
645 PM EDT SUN MAY 19 2013

.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 224 PM EDT SUN MAY 19 2013

A LARGE UPPER LOW CURRENTLY OVER THE PLAINS IS EXPECTED TO BRING
UNSETTLED WEATHER TO THE AREA THROUGH THURSDAY AS IT SLOWLY MOVES
EAST AND WEAKENS WITH TIME. HIGH PRESSURE IS EXPECTED TO BUILD IN
BEHIND THIS SYSTEM TOWARDS THE END OF THE WEEK. ANOTHER FRONTAL
SYSTEM MAY APPROACH THE AREA BY NEXT SUNDAY.

&&

.NEAR TERM /TONIGHT/...
ISSUED AT 224 PM EDT SUN MAY 19 2013

MODEL DATA SUGGEST FAIRLY STRONG 850MB WARM ADVECTION WILL BE
DEVELOPING ACROSS THE AREA BY LATE TONIGHT AS A 40-45KT LOW LEVEL
JET IS PROGGED TO NOSE TOWARDS INTO WESTERN INDIANA BY SUNRISE
MONDAY. SOME CONCERN THAT THIS MAY LEAD TO SOME ELEVATED CONVECTION
DURING THE PRE DAWN HOURS OF MONDAY GIVEN THE VERY STEEP MID LEVEL
LAPSE RATES EXPECTED OVER THE AREA. MODELS INDICATE SOME ENHANCED
MOISTURE IN THE PRECIPITATION BEARING LAYER AS WELL. AT THIS
POINT...DON/T THINK COVERAGE/POTENTIAL IS HIGH ENOUGH FOR A
MENTION IN THE FORECAST...SO WILL KEEP THE FORECAST DRY.

LOW LEVEL THICKNESSES PROGS GENERALLY SUPPORT THE GFS MOS LOWS
TONIGHT...SO LITTLE ADJUSTMENT TO THE GUIDANCE.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
ISSUED AT 224 PM EDT SUN MAY 19 2013

MAIN FEATURE DURING THIS PERIOD WILL BE THE LARGE UPPER LOW OVER THE
PLAINS THAT IS EXPECTED TO GRADUALLY OPEN UP AND MOVE INTO THE
MIDWEST BY WEDNESDAY...KEEPING THE SHORT TERM UNSETTLED.

SOME OF THE FINER SCALE MODELS SUGGEST THERE MAY SOME SORT OF
BOUNDARY...POSSIBLY ORIGINATING FROM CONVECTIVE ACTIVITY TO THE
WEST TONIGHT...THAT MAY MOVE INTO THE AREA AROUND MIDDAY ON
MONDAY. AIR MASS IS PROGGED TO BECOME VERY UNSTABLE ON
MONDAY...LI/S DOWN TO ABOUT -8...UNDERNEATH STEEP MID LEVEL LAPSE
RATES. WILL GO WITH CHANCE POPS STARTING AROUND MIDDAY AND ON INTO
THE AFTERNOON.

AFTER MONDAY...DETAILS BECOME A BIT MORE MURKY AS ROUNDS OF
CONVECTION ASSOCIATED WITH THIS SYSTEM MAY TEND TO BLUR THE COLD
FRONT POSITION. MODEL DATA SUGGEST ACTUAL COLD FRONT MAY NOT MOVE
THROUGH UNTIL WEDNESDAY NIGHT OR LATER. MODEL DATA DOES SUGGEST
LAPSE RATES GRADUALLY BECOME POORER WITH TIME AS AIR MASS GETS
WORKED OVER...ALTHOUGH DEEP LAYER SHEAR MAY TEND TO INCREASE SOME
TOWARDS TUESDAY AND WEDNESDAY. AT THIS POINT...CAN/T REALLY PIN DOWN
ANY PERIODS TO CONCENTRATE POPS ON...SO WITH BROADBRUSH HIGH CHANCE
POPS FROM MONDAY NIGHT THROUGH WEDNESDAY.

PROGGED LOW LEVEL THICKNESSES SUGGEST THE GFS MOS HIGHS FOR MONDAY
AND TUESDAY MAY BE A BIT ON THE WARM SIDE...ESPECIALLY WITH THE
POTENTIAL FOR CONVECTION OR ITS REMNANTS AROUND. WILL NUDGE THE
HIGHS DOWN A BIT. LOWS LOOK OK.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 224 PM EDT SUN MAY 19 2013

ECMWF AND GFS BOTH INDICATE A FRONTAL BOUNDARY AND ASSOCIATED UPPER
TROUGH EXITING THE RGN ON WEDNESDAY NIGHT AND EARLY ON THURSDAY. A
STRONG RIDGE ALOFT THEN BUILDS ACROSS THE OHIO VALLEY FOR FRIDAY AND
SATURDAY FROM THE CENTRAL PLAINS ALONG WITH COOLER AND DRY NW FLOW.
THUS WILL KEEP SOME CHCS FOR TSRA ON WEDNESDAY NIGHT AND SHRA ON
THURSDAY IN THE CYCLONIC FLOW ON THURSDAY. HOWEVER DRY WEATHER WILL
BE EXPECTED AS THE WORK WEEK CONCLUDES ON FRIDAY ALONG WITH TEMPS AT
OR ONLY SLIGHTLY ABOVE NORMALS.

ECMWF HINTS AT A WARM FRONT AND A WEAK S/W WAVE PUSHING INTO THE
AREA ON SUNDAY AND FOR NOW HAVE INCLUDED SOME LOW CHC POPS.

&&

.AVIATION /DISCUSSION FOR THE 200000Z TAF ISSUANCE/...

ISSUED AT 645 PM EDT SUN MAY 19 2013

VFR CONDITIONS EXPECTED TONIGHT WITH ONLY HIGH CLOUDS AS DIURNAL CU
DISSIPATES. MODELS SHOWING LINGERING LOW LEVEL MOISTURE...BUT THINK
FOG WILL NOT BE A PROBLEM LIKE LAST NIGHT AS SURFACE PRESSURE
GRADIENT PICKS UP AHEAD OF THE PLAINS FRONTAL SYSTEM WHICH SHOULD
KEEP SOUTH WINDS 5 KNOTS OR MORE. THE EXCEPTION COULD BE AT
BMG...WHERE GRADIENT WILL BE A BIT WEAKER WHICH SHOULD ALLOW SOUTH
WINDS TO DROP BELOW 5 KNOTS. THIS COULD ONCE AGAIN RESULT IN SOME
IFR FOG AT BMG AFTER 08Z THROUGH ABOUT 13Z. WOULD ALSO NOT RULE OUT
SOME LOW STRATUS OVERNIGHT...BUT FOR NOW WILL ONLY GO WITH SCATTERED
LOW STRATUS AT IND AND BMG AFTER 08Z.

WOULD NOT RULE OUT THUNDERSTORMS AFTER 14Z TOMORROW...BUT WITH
COVERAGE EXPECTED TO BE SCATTERED AT BEST AND BEING SO FAR
OUT...WILL HOLD OFF ON VCTS FOR NOW. SHOULD SEE SCATTERED TO BROKEN
DIURNAL VFR CU TOMORROW AFTERNOON. WINDS WILL BE INCREASING TOMORROW
WITH SOUTH AND SOUTHWEST WINDS INCREASING TO AROUND 15 KNOTS WITH
GUSTS TO 23 KNOTS AFTER 14Z.

&&

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

$$

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

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