Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 162000
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
300 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 /TONIGHT/...

ISSUED AT 142 PM EST TUE DEC 16 2014

SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS LOW PRESSURE OVER
SOUTHERN LAKE MICHIGAN WITH BROAD CYCLONIC FLOW ACROSS INDIANA AND
THE REST OF THE OHIO VALLEY. SATELLITE CONTINUED TO SHOW
EXTENSIVE CLOUDINESS FOUND ACROSS THE REGION WITH CLOUDS
STRETCHING BACK WEST TO MISSOURI...NEBRASKA AND IOWA. TEMPERATURES
ACROSS THE AREA WERE IN THE 40S...HOWEVER COLDER AIR IN THE 30S
WAS FOUND ACROSS NORTHERN ILLINOIS AND HEADED THIS WAY.

MAIN FORECAST CHALLENGE TONIGHT WILL BE CLOUDS AND ANY FREEZING
PRECIPITATION.

FORECAST SOUNDINGS AND TIME HEIGHTS CONTINUE TO SUGGEST TRAPPED
LOWER LEVEL MOISTURE LINGERING ACROSS THE STATE TONIGHT...SHOWING
SATURATION AND HIGH RH THROUGH THE NIGHT. ALOFT THE GFS 290K
ISENTROPIC SURFACE SHOWS GOOD SINKING AND ASSOCIATED DRYING. THUS
IS THIS AN IDEAL SITUATION FOR DRIZZLE. HOWEVER ONGOING COLD AIR
ADVECTION THROUGH THE NIGHT IS EXPECTED TO RESULT IN TEMPERATURES
FALLING BELOW 32F AFTER 06Z. FORECAST SOUNDINGS SHOW LOWER LEVELS
BELOW FREEZING. THUS WE COULD SEE SOME FLURRIES OR FREEZING
DRIZZLE. WILL MENTION THIS IN THE FORECAST...HOWEVER POPS WILL BE
MINIMAL AS CHANCES MEASURABLE PRECIP IS LOW GIVEN THE WEAK FORCING.

AS FOR TEMPS WILL TREND LOWS AT OR SLIGHTLY ABOVE MAVMOS AS
CLOUDS ARE EXPECTED TO LINGER...AS WELL AS WEST WINDS AT 10-15 MPH
PROVIDING MIXING.

&&

.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 162100Z TAF ISSUANCE/...
ISSUED AT 300 PM EST TUE DEC 16 2014

UPDATED CURRENT CONDITIONS ONLY. PREVIOUS DISCUSSION FOLLOWS...

IFR CONDITIONS CONTINUE THIS AFTERNOON...GRADUAL IMPROVEMENTS IN
CEILINGS TO MVFR BY WEDNESDAY MORNING.

LOW PRESSURE SLOWLY TRACKING EAST ACROSS THE GREAT LAKES THIS
AFTERNOON WITH ABUNDANT LOW LEVEL MOISTURE AND LIGHT SHOWERS
ACCOMPANYING IT. CEILINGS HAVE BEEN HOVERING BETWEEN 500 AND
1500FT FOR THE MOST PART AS THE NEAR SURFACE LAYER REMAINS
SATURATED. EXPECT SCATTERED LIGHT PRECIP TO LINGER THROUGH THE
AFTERNOON WITH IFR CONDITIONS PERSISTING. WINDS WILL VEER TO
WESTERLY AND GUST TO 20-25KTS WITH THE PASSAGE OF A WEAK BOUNDARY
THIS AFTERNOON AS WELL.

DRIER AIR WILL FILTER INTO THE REGION THIS EVENING BUT MODEL
SOUNDINGS SHOW THE CONTINUED PRESENCE OF A SHALLOW INVERSION WHICH
WILL MAINTAIN THE STRATUS DECK BETWEEN 1000-2000FT. FLURRIES ARE
POSSIBLE THIS EVENING AS DEEP MOISTURE IS LOST AND THE AIRMASS
COOLS. COULD EVEN SEE A BRIEF PERIOD WITH FREEZING DRIZZLE AFTER
06Z AS FURTHER DRYING OCCURS ABOVE THE INVERSION. NOT MAKING A
MENTION OF FREEZING DRIZZLE AT THIS POINT...BUT WILL BE SOMETHING
TO MONITOR. MVFR STRATUS WILL REMAIN ON WEDNESDAY MORNING DESPITE
HIGH PRESSURE BUILDING IN. GUSTS WILL DIMINISH THIS EVENING...WITH
W/NW WINDS PERSISTING AT 10-15KTS FOR MUCH OF THE REST OF THE
FORECAST PERIOD.

&&

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

&&

$$

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

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