Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 222039
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
339 PM EST SAT NOV 22 2014

.UPDATE...
AVIATION SECTION UPDATED.

&&

.SYNOPSIS...
ISSUED AT 211 PM EST SAT NOV 22 2014

AN ACTIVE WEATHER PATTERN IS SET FOR THE REST OF THE WEEKEND AS A
STRONG LOW PRESSURE SYSTEM OVER THE SOUTHERN PLAINS IS EXPECTED TO
SWEEP NORTHEAST TO THE GREAT LAKES. THIS WILL BRING SHOWERS AND
PERHAPS A THUNDERSTORM TO CENTRAL INDIANA ON SUNDAY AND SUNDAY
NIGHT.

A COLD FRONT ASSOCIATED WITH THE LOW WILL SWEEP ACROSS THE STATE
ON MONDAY. THIS WILL BRING ANOTHER ROUND OF PRECIP TO CENTRAL INDIANA
WHICH MAY MIX WITH AND CHANGE OVER TO SNOW ON MONDAY AFTERNOON.
COLD HIGH PRESSURE WILL THEN BUILD ACROSS CENTRAL INDIANA FOR THE
MIDDLE OF THE WORK WEEK.

ANOTHER STORM SYSTEM WILL APPROACH CENTRAL FOR THANKSGIVING GIVING
CENTRAL INDIANA MORE CHANCES FOR SNOW.

&&

.NEAR TERM /TONIGHT/...

ISSUED AT 211 PM EST SAT NOV 22 2014

SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS HIGH PRESSURE IN PLACE
ACROSS THE CAROLINAS. WARMER SOUTHERLY FLOW WAS IN PLACE ACROSS
INDIANA AND DEW POINT TEMPS WERE RISING IN TO THE LOWER 40S. IR
PICTURES SHOW A STREAM OF CLOUDS STRETCHING FROM THE SOUTHERN
PLAINS TO INDIANA AND OHIO. RADAR ONLY SHOWS A FEW SCATTERED LIGHT
RAIN SHOWERS ACROSS THE AREA...QUICKLY MOVING NORTHEAST.

NAM AND GFS CONTINUES TO SUGGEST LITTLE UPPER SUPPORT AS AN UPPER
WAVE BEGINS TO PUSH OUT OF THE SOUTHERN PLAINS. FORECAST SOUNDINGS
TONIGHT SHOW PLENTIFUL MOISTURE AVAILABLE...BUT RELATIVELY DRY
AIR IN THE LOWER LEVELS. 295K GFS ISENTROPIC SURFACE SHOWS
BROAD...WEAK LIFT...BUT AGAIN PLENTIFUL MOISTURE AS SPECIFIC
HUMIDITIES WERE IN EXCESS OF 5 G/KG.

THUS WITH WEAK FORCING IN PLACE AND PLENTY OF MOISTURE...WILL
TREND POPS SLIGHTLY ABOVE MAVMOS...ALTHOUGH ANY PRECIP THAT DOES
OCCUR OVERNIGHT SHOULD BE RELATIVELY LIGHT AS FORCING IS WEAK.

AS FOR TEMPS...WITH EXPECTED CLOUDS...POSSIBLE RAIN AND ONGOING
BROAD WARM AIR ADVECTION...WILL TREND LOWS AT OR ABOVE MAVMOS.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...

ISSUED AT 211 PM EST SAT NOV 22 2014

ACTIVE WEATHER DAY IS IN STORE FOR SUNDAY AS THE GFS AND NAM BOTH
AGREE THAT THE TROUGH OVER THE CENTRAL UNITED STATES WILL DRIFT
EAST AND DEEPEN. AS IT DOES STRONG DYNAMICS WILL BE EJECTED OUT
OF THE TROUGH AND PUSHED ACROSS THE OHIO VALLEY. VERY GOOD LOWER
LEVEL MOISTURE WILL REMAIN IN PLACE AS SOUTHERLY FLOW WILL STILL
REMAIN FROM THE DEPARTING HIGH. FORECAST SOUNDINGS AND TIME
HEIGHTS THEN SHOW DEEP SATURATION WITH EXCELLENT LIFT BY 00Z
MONDAY. AT THE SURFACE A DEEPENING LOW PRESSURE SYSTEM IS EXPECTED
TO PUSH OUT OF THE SOUTHERN PLAINS AND REACH THE GREAT LAKES AND
IT STRENGTHENS BY MONDAY MORNING. ALL THE WHILE...PUSHING A WARM
FRONT ACROSS CENTRAL INDIANA ON SUNDAY NIGHT AND PUTTING US IN THE
WARM SECTOR. THUS GIVEN ALL THE DYNAMIC SUPPORT WILL USE NEAR 100
POPS ON SUNDAY AND SUNDAY NIGHT.

SHEAR IS VERY IMPRESSIVE AS THIS SYSTEM DEEPENS AND
PASSES...HOWEVER FORECAST SOUNDINGS CONTINUE TO SUGGEST LOWER
LEVEL INVERSIONS IN PLACE. HOWEVER ALOFT...SOME INSTABILITY WILL
REMAIN PRESENT AS STEEP LAPSE RATES LOOK PRESENT AMID A SATURATED
COLUMN. THUS WILL INCLUDE SOME THUNDER FOR SUNDAY AFTERNOON AND
SUNDAY NIGHT AS THE BEST FORCING PASSES.

AS FOR TEMPS WILL STICK CLOSE TO THE MAVMOS GIVEN THE EXPECTED
CLOUDS AND WARM AIR ADVECTION COUNTERACTING EACH OTHER...AND TREND
WARMER ON SUNDAY NIGHT AS SOUTHERLY FLOW IS EXPECTED TO PERSIST
WITHIN THE WAKE OF THE PASSING WARM FRONT TO THE NORTH.

ANOTHER ROUND OF PRECIP LOOK LIKELY ON MONDAY AS ONCE AGAIN DECENT
MOISTURE APPEARS AVAILABLE AS A COLD FRONT SWEEPS ACROSS THE
STATE DURING THE MORNING HOURS. FORECAST SOUNDING INITIALLY SHOW
LOWER LEVELS WELL ABOVE FREEZING ON MONDAY MORNING...BUT AS THE
STRONG COLD AIR ADVECTION BEGINS IN THE WAKE OF THE COLD
FRONT...SOUNDINGS ONCE AGAIN FALL ENTIRELY BELOW FREEZING SHOWING
A SNOW SOUNDING. THUS WILL START THE DAY OFF WITH RAIN CHANCES IN
THE MORNING AND TREND TOWARD SNOW CHANCES IN THE AFTERNOON. AT
THIS TIME BEST MOISTURE AND FORCING WILL BE LONG GONE AND PASSED
TO THE EAST...THUS ONLY MINIMAL TO VERY LIGHT ACCUMULATIONS WILL
BE POSSIBLE. AS FOR TEMPS ON MONDAY...GIVEN THE COLD AIR
ADVECTION...WE WILL LOOK FOR HIGHS IN THE MORNING...WITH TEMPS
FALLING INTO THE 30S IN THE AFTERNOON. A NON-DIURNAL TREND WILL BE
USED WITH DAYTIME HIGHS REACHED SHORTLY BETWEEN 13-15Z NEAR FROPA.

A RIDGE OF COLD HIGH PRESSURE WILL THEN BEGIN TO WORK INTO THE
AREA ON MONDAY NIGHT AND TUESDAY...BRINGING ANOTHER BURST OF COLD
AND DRY AIR WITH BELOW NORMAL TEMPS. FORECAST SOUNDINGS
AGREE...SHOWING A DRY COLUMN ALONG WITH SOUNDINGS ENTIRELY BELOW
0C. WILL TREND TEMPS AT OR BELOW MAVMOS.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...

ISSUED AT 243 PM EST SAT NOV 22 2014

THE LONG TERM STARTS OUT DRY WITH WEAK SURFACE HIGH PRESSURE SLIDING
THROUGH. ON WEDNESDAY AN UPPER WAVE AND SURFACE SYSTEM WILL START TO
APPROACH INDIANA AND WILL BRING PRECIPITATION CHANCES INTO THE AREA
FOR WEDNESDAY NIGHT AND THURSDAY. STILL SEEING BIG VARIABILITY IN
ENSEMBLES AND OPERATIONAL SOLUTIONS ESPECIALLY IN TERMS OF
TEMPERATURES ON THURSDAY AND THIS WILL HAVE A DIRECT IMPACT ON
PRECIPITATION TYPE. ENSEMBLE MOS HIGHS IN THE GFS ARE VARYING FROM
29 TO 48 FOR INDIANAPOLIS...THE OPERATIONAL GFS IS STICKING CLOSER
TO THE WARMER END OF THE ENVELOPE AND THE OPERATIONAL ECMWF IS
STICKING WITH A COLDER TRACK. WITH THE ECM TENDING TO VERIFY A
LITTLE BETTER FURTHER OUT IN TIME WILL TREND THE INTIALIZATION A FEW
DEGREES COLDER TOWARD IT...AND THIS RESULTED IN CHANCES FOR SNOW
NORTH AND A RAIN/SNOW MIX SOUTH FOR BOTH WEDNESDAY NIGHT AND
THURSDAY. PATTERN COULD FLATTEN A BIT AFTER THAT AND ACCEPTED DRY
INITIALIZATION FOR FRIDAY-SATURDAY.

&&

.AVIATION /DISCUSSION FOR THE 202100Z IND TAF UPDATE/...

ONGOING TAFS ARE IN GOOD SHAPE AS VFR CONDITIONS CONTINUE. HAVE
REMOVED THE SHRA MENTION TEMPO GROUP FOR NOW AS VCSH APPEARS TO
HAVE THINGS COVERED. WILL WATCH PROPAGATION OF PRECIP AREA OVER
SOUTHERN ILLINOIS CLOSELY AS THAT LOOKS LIKE OUR NEXT BEST CHANCE
FOR PRECIP.

PREVIOUS DISCUSSION BELOW

/DISCUSSION FOR 221800Z TAF ISSUANCE/...

ISSUED AT 1234 PM EST SAT NOV 22 2014

VFR CONDITIONS WITH SCATTERED VERY LIGHT SHOWERS AND LOW LEVEL WIND
SHEAR SHOULD CONTINUE THROUGH THE AFTERNOON. LOW LEVEL JET SHOULD
WEAKEN SOME LATER THIS AFTERNOON ENOUGH TO DROP MENTION OF LLWS BY
AROUND 23Z. TIME HEIGHTS SHOW LOW LEVEL MOISTURE INCREASING DURING
THE OVERNIGHT AND EXPECT TO SEE MVFR CLOUD DECK DEVELOP BETWEEN
AROUND 9-12Z AND MORE RAIN TO DEVELOP AFTER THAT. RIGHT NOW WILL GO
WITH LOW END MVFR BUT WILL NEED TO WATCH FOR LOWER CEILINGS AS
SYSTEM APPROACHES.


&&

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

$$

SYNOPSIS...PUMA
NEAR TERM...PUMA
SHORT TERM...PUMA
LONG TERM....CP
AVIATION...CP/JP

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