Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 170756
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
256 AM EST WED DEC 17 2014

.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW.

&&

.SYNOPSIS...
ISSUED AT 254 AM EST WED DEC 17 2014

HIGH PRESSURE IS EXPECTED TO BUILD INTO THE AREA FOR THE NEXT FEW
DAYS. A LOW PRESSURE SYSTEM MAY AFFECT THE AREA BY THE END OF THE
WEEK. A STRONGER SYSTEM MAY AFFECT THE AREA BY THE EARLY TO MIDDLE
PARTS OF NEXT WEEK.

&&

.NEAR TERM /TODAY/...
ISSUED AT 254 AM EST WED DEC 17 2014

STILL SOME AREAS OF FREEZING DRIZZLE/FLURRIES AROUND BASED ON RADAR
AND SURFACE OBSERVATIONS...MAINLY OVER THE EASTERN ZONES. SHORT TERM
MODELS SUGGEST THERE MAY BE A LOW LEVEL VORTICITY LOBE ASSOCIATED
WITH THIS PRECIPITATION...WHICH THE MODELS MOVE EAST OF THE FORECAST
AREA PRIOR TO SUNRISE. AS A RESULT...THINK ANY PRECIPITATION THAT
MAY BE LEFT DURING THE PRE DAWN HOURS WILL BE OVER BY SUNRISE.

OTHERWISE...MODELS INDICATE A STOUT SUBSIDENCE INVERSION WILL
CONTINUE TODAY...SO EXPECTING LITTLE IN THE WAY OF CLEARING. THE FAR
SOUTHWEST ZONES MAY SEE SOME BREAKS AROUND SUNSET...BUT THAT WOULD
BE ABOUT IT.

GIVEN COLD ADVECTION AND CLOUD COVER...THE GFS MOS HIGHS FOR TODAY
ARE PROBABLY TOO WARM. WILL CUT THE HIGHS BY A CATEGORY.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 254 AM EST WED DEC 17 2014

UPPER BLOCK OVER SOUTHERN CANADA EXPECTED TO BREAK DOWN DURING THIS
PERIOD...AS A NORTHERN STREAM DISTURBANCE DIGS INTO THE NORTHERN
MIDWEST BY FRIDAY NIGHT AND SOUTHERN STREAM SYSTEM SCOOTS ALONG THE
GULF COAST STATES.

MODELS CONTINUE TO SUGGEST THERE MAY BE SOME LIFT DEVELOPING OVER
THE SURFACE HIGH PRESSURE RIDGE ON THURSDAY. THE PRECIPITATION
BEARING LAYER APPROACHES SATURATION ON THURSDAY...BUT THE LIFT LOOKS
RATHER WEAK AND THERE IS QUITE A BIT OF DRY AIR BELOW THE
PRECIPITATION BEARING LAYER. AT THIS TIME...IF ANYTHING HAPPENS IT
LOOKS MORE LIKE A FLURRY OR TRACE EVENT...WITH THE CHANCES FOR
MEASURABLE TOO LOW TO MENTION.

SOME LIFT IS EXPECTED TO MOVE BACK INTO THE AREA BY FRIDAY NIGHT AND
THE NORTHERN AND SOUTHERN STREAM SHORT WAVE TROUGHS APPROACH. MODEL
DATA SUGGEST THE SOUTHERN ZONES WILL HAVE THE BEST CHANCE FOR
SATURATION OF THE PRECIPITATION BEARING LAYER...SO WILL GO WITH CHANCE
POPS FOR LIGHT SNOW BY LATE FRIDAY NIGHT IN THOSE AREAS.

APPEARS THERE WILL BE QUITE A BIT OF CLOUD COVER AROUND OVER THE
NEXT FEW DAYS. AS A RESULT...WILL NARROW THE DIURNAL RANGE OF THE
GFS MOS TEMPERATURE GUIDANCE ALL PERIODS.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
ISSUED AT 228 PM EST TUE DEC 16 2014

A MORE ACTIVE PATTERN SHAPING UP THROUGH THE EXTENDED WITH TWO
CHANCES FOR STORMS TO IMPACT THE REGION.

FIRST FOCUS REMAINS ON THE POTENTIAL SNOW SYSTEM TO IMPACT THE
OHIO VALLEY LATE FRIDAY NIGHT INTO SATURDAY. MODEL CONSENSUS SANS
THE OP GFS REMAINS CLUSTERED ON A WEAKER SYSTEM WITH A MORE
SUPPRESSED TRACK ALONG THE NORTHERN GULF COAST DUE TO LITTLE
PHASING BETWEEN THE POLAR AND SUBTROPICAL JETS. PRESENCE OF THE
NORTHERN STREAM UPPER WAVE HOWEVER WILL EFFECTIVELY BRING MOISTURE
NORTH INTO THE REGION LATE FRIDAY NIGHT AND CONTINUE ON SATURDAY
AS THE WAVE PASSES THROUGH. WILL MAINTAIN CHANCE POPS FOR THE
ENTIRE FORECAST AREA ON SATURDAY...WITH THE POTENTIAL FOR LIGHT
AMOUNTS OF SNOW BY SATURDAY EVENING.

HIGH PRESSURE AND RIDGING ALOFT WILL FOLLOW THE UPPER WAVE
SETTING THE STAGE FOR A DRIER END TO THE WEEKEND. INTERESTING
TRENDS THEN DEVELOPING AS THE HOLIDAY WEEK PROGRESSES WITH SOME
STRONG INDICATIONS OF A MORE AMPLIFIED UPPER LEVEL PATTERN
DEVELOPING OVER THE COUNTRY. PRESENCE OF A STRONG RIDGE OFF THE
PACIFIC COAST WILL PROMOTE A DOWNSTREAM TROUGH EAST OF THE ROCKIES
BY THE MIDDLE OF NEXT WEEK. PRECIPITATION WILL RETURN TO CENTRAL
INDIANA BY TUESDAY WITH THE APPROACH OF A COLD FRONT. BRIEF
WARMING AHEAD OF THE FRONT MAY ENABLE PRECIP TO FALL AS A
RAIN/SNOW MIX ON TUESDAY BEFORE MUCH COLDER AIR OVERSPREADS THE
REGION WITH THE AMPLIFYING UPPER TROUGH. ECMWF IN PARTICULAR
HINTING AT AN INTENSIFYING SURFACE WAVE ON THE TRAILING FRONT AND
LIFTING THROUGH THE OHIO VALLEY ON CHRISTMAS EVE AS A WINTER STORM.
REALLY EARLY IN THE PROCESS AT THIS POINT...BUT WILL NEED TO
MONITOR IN THE COMING DAYS AS SOME GROWING POTENTIAL FOR PRE-
HOLIDAY TRAVEL DISRUPTIONS NEXT TUESDAY AND WEDNESDAY. STAY TUNED.

&&

.AVIATION /DISCUSSION FOR 170600Z TAF ISSUANCE/...

ISSUED AT 1200 AM EST WED DEC 17 2014

A MIXTURE OF IFR/MFVR CONDITIONS WILL CONTINUE THROUGH THE EARLY
OVERNIGHT PERIOD...THEN EXPECT GRADUAL IMPROVEMENTS IN CEILINGS
TO LOW END MVFR BY LATE THIS MORNING. AND POSSIBLY VFR AT A FEW OF
THE SITES (NAMELY KLAF) BY LATER THIS AFTERNOON...FOR A VERY BRIEF
PERIOD BEFORE AN INVERSION DEVELOPS AGAIN BY THE EVENING AND ALL
SITES MAINTAIN AN MVFR STRATUS DECK ONCE AGAIN. LEANED CLOSER TO
THE NAM GUIDANCE WHICH MORE ACCURATELY DEPICTS THIS HAPPENING AS
OPPOSED TO THE OVERLY OPTIMISTIC MAV/GFS WHICH IS COMMON DURING
THIS TIME OF YEAR.

GUSTS WILL CONTINUE TO DIMINISH TOWARD THE START OF THIS TAF
PERIOD...WITH W/NW WINDS PERSISTING AROUND 10KTS FOR MUCH OF THE
REST OF THE FORECAST PERIOD...UNTIL LATE THIS EVENING WHEN WINDS
BECOME LIGHTER...AOB 5KT OUT THE NW.

-SHSN SHOULD BE COMING TO AN END AT THE EASTERN MOST TAF SITES
(KIND/KBMG) BY 8/9Z.

&&

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

$$

SYNOPSIS...JAS
NEAR TERM...JAS
SHORT TERM...JAS
LONG TERM....RYAN
AVIATION...SMF

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