Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 170446
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1146 PM EST TUE DEC 16 2014

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

&&

.SYNOPSIS...
ISSUED AT 142 PM EST TUE DEC 16 2014

LOW PRESSURE OVER THE GREAT LAKES WILL DEPART SLOWLY TO THE EAST
TONIGHT AS HIGH PRESSURE OVER THE UPPER MIDWEST BUILDS INTO THE
OHIO VALLEY THROUGH WEDNESDAY AND THURSDAY.

THE HIGH WILL PROVIDE SOME COOLER CANADIAN AIR TO THE
AREA...RESULTING IN COLDER TEMPERATURES THAN THE PAST FEW DAYS.

THE NEXT BEST CHANCE FOR PRECIPITATION WILL BE FRIDAY NIGHT INTO
SATURDAY AS A LOW PRESSURE SYSTEM AND AN ASSOCIATED UPPER LEVEL
WEATHER DISTURBANCE MOVES THROUGH THE SOUTH.

&&

.NEAR TERM /REST OF TONIGHT/...

ISSUED AT 824 PM EST TUE DEC 16 2014

FOR THE UPDATE...HAVE SEEN SOME ECHOES DEVELOP ACROSS THE AREA WITH
AN UPPER IMPULSE MOVING THROUGH. THESE ARE MORE INTENSE THAN JUST
DRIZZLE SO EARLIER UPDATED THE FORECAST TO INCLUDE A CHANCE FOR RAIN
AND SNOW ACROSS MOST OF THE AREA FOR THE NEXT COUPLE OF HOURS...AND
OBSERVATIONS HAVE BEEN REPORTING BOTH PRECIPITATION TYPES UNDER
THESE ECHOES. ANY MEASURABLE PRECIPITATION /WATER EQUIVALENT...NOT
ANTICIPATING ACCUMULATING SNOW/ WITH THIS WAVE SHOULD MOVE OUT IN
THE NEXT COUPLE OF HOURS BUT LOW LEVEL MOISTURE AND CYCLONIC FLOW
WILL REMAIN AS WELL AS TEMPERATURES THAT SHOULD BE DROPPING BELOW
FREEZING IN THE NEXT FEW HOURS. THUS THINK CHANCES FOR FLURRIES AND
FREEZING LIGHT DRIZZLE WILL CONTINUE THROUGH MUCH OF THE
OVERNIGHT...FINALLY ENDING FROM SOUTHWEST TO NORTHEAST AS THE
SURFACE LOW PULLS FURTHER AWAY. ROAD TEMPERATURES ARE STILL RUNNING
IN THE MID TO UPPER 30S SO IMPACT SHOULD BE MINIMAL WITH THE
POSSIBLE EXCEPTION OF ELEVATED LOCATIONS SUCH AS BRIDGES THAT COULD
COOL FASTER.

LOW TEMPERATURES STILL LOOK ON TRACK FOR THE MID 20S TO AROUND 30
WITH CLOUDY SKIES EXPECTED THROUGH THE NIGHT AND WINDS STAYING UP
SOME.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...

ISSUED AT 142 PM EST TUE DEC 16 2014

ON WEDNESDAY THE SLOWLY MOVING SURFACE LOW IS EXPECTED TO REACH
SOUTHEAST ONTARIO...AS HIGH PRESSURE BUILDS ACROSS THE MISSISSIPPI
VALLY THROUGH THE CENTER OF THE CONUS. LOWER LEVEL FLOW LOOKS TO
REMAIN CYCLONIC ON WEDNESDAY AND RIDGING REMAINS IN PLACE ALOFT TO
THE WEST. THIS KEEPS INDIANA ON THE LEE SIDE OF THE RIDGE AND
CONFIDENCE IN CLEARING IS LOW. FURTHER SUPPORT IS SEEN THE THE
TIME HEIGHT SECTIONS WHICH CONTINUE TO DISPLAY A THIN LAYER OF
TRAPPED LOWER LEVEL MOISTURE. THUS WILL TREND SKIES TOWARD MOSTLY
CLOUDY ON WEDNESDAY. WILL ALSO TREND TEMPS AT OR BELOW MAVMOS
GIVEN THE EXPECTED CLOUDS AND ONGOING COLD AIR ADVECTION.

BY WEDNESDAY NIGHT THE SURFACE LOW MOVES TO EASTERN NEW ENGLAND
AND HIGH PRESSURE IS FIRMLY ESTABLISHING ITSELF FROM THE UPPER
MIDWEST THROUGH THE OHIO VALLEY TO THE DEEP SOUTH. RIDGING IN THE
MIDDLE LEVEL ARRIVES IN CENTRAL INDIANA AND THE LOWER LEVEL
CYCLONIC FLOW COMES TO AN END. THUS WILL CLEAR SKIES OUT ON
WEDNESDAY NIGHT AS THE HIGH MOVES THROUGH THE AREA. GIVEN THE
IDEAL RADIATIONAL COOLING SET UP WITH CLEAR SKIES AND LIGHT WINDS
WILL TREND LOWS AT OR BELOW MAVMOS.

THURSDAY THROUGH FRIDAY CONTINUE TO LOOK DRY AT THIS TIME WITH
INCREASING CLOUDS THROUGH THE PERIOD. ALOFT A WEAK SHORT WAVE WILL
STREAM THROUGH THE OHIO AND TENNESSEE RIVER VALLEYS ON THURSDAY AND
EXIT ON FRIDAY...BUT NO MOISTURE APPEARS AVAILABLE AS SURFACE
HIGH PRESSURE ACROSS THE AREA KEEPS DRY CONTINENTAL AIR IN PLACE.
SOME WARM AIR ADVECTION IS EXPECTED TO BEGIN ON THE BACKSIDE OF
THE HIGH ON THURSDAY. THE GFS ALSO SUGGESTS WEAK LOW PRESSURE
PUSHING INTO OKLAHOMA AND NORTHERN TEXAS. THE 290K GFS ISENTROPIC
SURFACE REVEALS GOOD LIFT ACROSS OK AND TX...BUT THIS LIFT DOES
RESULT IN THE ARRIVAL OF SOME HIGH CLOUDS ACROSS THE OHIO VALLEY.
FORECAST SOUNDINGS SHOW MID AND HIGHER LEVEL SATURATION BEGINNING
THURSDAY AS THIS WEAK LOW BEGINS ITS TREK THROUGH THE DEEP SOUTH.
OVERALL MOISTURE REMAINS MINIMAL AS SURFACE HIGH PRESSURE REMAINS
IN PLACE OVER INDIANA. THUS WILL JUST TREND TOWARD INCREASING
CLOUDS ON THE THURSDAY THROUGH FRIDAY PERIOD. AS FOR TEMPS WILL
TREND HIGHS CLOSE TO MAV/MEX VALUES GIVEN THE RETURN OF WARM AIR
ADVECTION AND CLOUDS. WILL TREND LOWS THURSDAY NIGHT WARMER GIVEN
THE EXPECTED CLOUDS.

&&

.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...PUMA
NEAR TERM...PUMA/CP
SHORT TERM...PUMA
LONG TERM....RYAN
AVIATION...SMF

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