Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 191033
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
532 AM EST WED NOV 19 2014

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

&&

.SYNOPSIS...
ISSUED AT 341 AM EST WED NOV 19 2014

A QUICK MOVING COLD FRONT WILL BRING LIGHT SNOW TO MAINLY THE
NORTHERN HALF OF CENTRAL INDIANA TODAY. EXPECT COLD DRY WEATHER FOR
THE REMAINDER OF THE WORK WEEK AS HIGH PRESSURE TRACKS THROUGH THE
MIDWEST. UNSETTLED WEATHER WILL RETURN FOR THE WEEKEND ALONG WITH
WARMER TEMPERATURES AND EARLY NEXT WEEK AS TWO AREAS OF LOW PRESSURE
TRACK THROUGH THE REGION. THE PASSAGE OF A COLD FRONT EARLY NEXT
WEEK WILL USHER IN COLDER TEMPERATURES.

&&

.NEAR TERM /TODAY/...
ISSUED AT 341 AM EST WED NOV 19 2014

MAINLY CLEAR SKIES OVER THE FORECAST AREA EARLY THIS MORNING...BUT
MID LEVEL CLOUDS QUICKLY APPROACHING FROM THE NORTHWEST AHEAD OF AN
UPPER WAVE. 08Z TEMPS WERE IN THE TEENS BUT MOST LOCATIONS HAD SEEN
TEMPS WARM A FEW DEGREES OVER THE LAST FEW HOURS WITH WARM ADVECTION
DEVELOPING.

FOCUS FOR TODAY IS ON LIGHT SNOW CHANCES AS AFOREMENTIONED UPPER
WAVE AND A COLD FRONT TRACK THROUGH THE REGION. CLOUDS WILL CONTINUE
TO OVERSPREAD THE FORECAST AREA WITH MOST LOCATIONS GENERALLY CLOUDY
BY OR SHORTLY AFTER DAYBREAK. SOUNDING PROFILES FOR THIS MORNING
SHOW LOW LEVEL MOISTURE LACKING SOMEWHAT DESPITE A LOW LEVEL JET
ACROSS THE OHIO VALLEY. DEEPER FORCING ALOFT SHOULD REMAIN CONFINED
CLOSER TO THE GREAT LAKES. WITH BOTH FORCING ALOFT AND LOW LEVEL
MOISTURE LIMITED...HARD TO JUSTIFY GOING HIGHER THAN 30-40 POPS OVER
THE NORTHERN HALF OF THE FORECAST AREA THIS MORNING AS THE WAVE
PASSES. WRF CAPTURES THIS THINKING WELL WITH LIGHT SNOW PASSING
ACROSS NORTHERN INDIANA DURING THE MORNING. COULD SEE A DUSTING UP
TO AROUND A HALF INCH MAINLY NORTH OF INDY.

ONCE THE FRONT AND WAVE PASS THIS AFTERNOON...MODEL SOUNDINGS
INDICATE A PERIOD WITH STEEPENING LAPSE RATES OVER A SHALLOW LAYER
ALONG WITH VERY WEAK INSTABILITY AS COLD ADVECTION RETURNS. THIS
WOULD SUPPORT POTENTIAL FOR LINGERING FLURRIES OR SNOW SHOWERS
THROUGH THE AFTERNOON WHICH COULD BRING AN ADDITIONAL FEW TENTHS OF
ACCUM IN LOCALIZED AREAS.

TEMPS...MAVMOS REMAINS FAR TOO AGGRESSIVE WITH ITS WARMING TODAY
CONSIDERING THE SNOWPACK OVER MUCH OF THE AREA AND THE PRESENCE OF
PLENTY OF CLOUDS FOR MUCH OF THE DAY. UNDERCUT MAV GENERALLY BY 3-4
DEGREES TODAY...WITH HIGHS LIKELY OCCURRING BY EARLY AFTERNOON
BEFORE SLOWLY FALLING AS COLD ADVECTION TAKES HOLD.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
ISSUED AT 341 AM EST WED NOV 19 2014

FORECAST CHALLENGES ARE ON PRECIP CHANCES AND TYPE FRIDAY NIGHT AS
MOISTURE RETURNS ON THE BACK SIDE OF STRONG HIGH PRESSURE.

REGION REMAINS UNDER INFLUENCE OF UPPER TROUGH TONIGHT AND WITH
MODEL SOUNDINGS HINTING AT DEVELOPMENT OF A SHALLOW INVERSION
TRAPPING MOISTURE INTO THE EVENING...WILL MAINTAIN MENTION OF
FLURRIES WITH MOSTLY CLOUDY SKIES. CLOUDS SHOULD SCATTER LATE
TONIGHT AS DRIER AIR ADVECTS INTO THE REGION WITH HIGH PRESSURE.

THE HIGH WILL BE THE DOMINANT INFLUENCE ON OUR WEATHER THROUGH
FRIDAY AS IT TRACKS THROUGH THE OHIO VALLEY. WITH COLD POOL ALOFT
REMAINING OVER CENTRAL INDIANA THURSDAY...DIURNAL CU FIELD WILL
REFORM FOR THE AFTERNOON. SKIES WILL CLEAR THURSDAY NIGHT WITH
MOSTLY SUNNY SKIES FOR FRIDAY AS THE CENTER OF THE HIGH PASSES
OVERHEAD.

WILL BEGIN TO SEE MID AND HIGH LEVEL CLOUDS INCREASE FROM THE
SOUTHWEST LATE IN THE DAY FRIDAY AS LOW PRESSURE ORGANIZES OVER
TEXAS. MOISTURE WILL STREAM NORTH INTO THE OHIO VALLEY FRIDAY NIGHT
ON THE BACK SIDE OF THE HIGH PRESSURE...WITH A LIGHT WINTRY MIX
DEVELOPING LATE. STILL QUITE A BIT OF MODEL DISCREPANCY PRESENT AT
THIS POINT IN TIME WITH RESPECT TO HOW QUICKLY THE WARMER NEAR
SURFACE AIR ADVECTS INTO THE REGION. STRENGTHENING ISENTROPIC LIFT
AND WARM ADVECTION COURTESY OF INCREASING WINDS AT 850MB WILL BRING
ABOVE FREEZING AIR INTO THE BOUNDARY LAYER AS THE NIGHT
PROGRESSES...BUT IS LIKELY TO OUTPACE THE WARMING IN THE NEAR
SURFACE LAYER. ADDITIONALLY SOME QUESTION STILL EXISTS WITH HOW
QUICKLY THE DRIER AIR IN THE LOWER LEVELS IS PUSHED OUT AS THE
DEEPER MOISTURE ARRIVES.

THESE UNCERTAINTIES POSE A LOW CONFIDENCE P-TYPE FORECAST AS THE
BOUNDARY LAYER SUFFICIENTLY MOISTENS LATE FRIDAY NIGHT. ECMWF
REMAINS MOST AGGRESSIVE WITH SURGE OF WARMER NEAR SURFACE
AIR...WHILE MOST OF THE OTHER MODELS ARE SLOWER IN WARMING THE
LAYER. CONSIDERING THE REMNANT SNOWPACK AND LINGERING ARCTIC AIRMASS
AND DRIER AIR WITHIN THE BOUNDARY LAYER...PREFER THE SLOWER NEAR
SURFACE WARMING SUGGESTED BY THE MODEL CONSENSUS. LOW LEVEL THERMAL
PROFILES SUPPORT A PERIOD OF LIGHT FREEZING RAIN OR POSSIBLY SLEET
LATE FRIDAY NIGHT WITH SURFACE TEMPS REMAINING SUBFREEZING FOR MOST
OF THE FORECAST AREA THROUGH DAYBREAK SATURDAY. AT THIS POINT...ANY
ICING ACCUM LOOKS MINIMAL.

TEMPS...COLDER TEMPERATURES RETURN FOR MUCH OF THE SHORT TERM WITH
THE RENEWED SURGE OF ARCTIC AIR BEHIND THE FRONT TODAY. TOOK A MOS
BLEND FOR HIGHS THROUGH THE PERIOD. LEANED TOWARDS COOLER MAVMOS FOR
LOWS TONIGHT AND THURSDAY NIGHT. LOWS FRIDAY NIGHT SHOULD BE DURING
THE EVENING WITH RISING TEMPS THE REST OF THE NIGHT AS WARM
ADVECTION STRENGTHENS. AS STATED ABOVE HOWEVER...EXPECT MOST OF THE
FORECAST AREA TO REMAIN SUBFREEZING THROUGH 12Z SATURDAY.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
ISSUED AT 341 AM EST WED NOV 19 2014

AN UNSETTLED PERIOD EXPECTED AS ENSEMBLES INDICATE ANOTHER DEEP LONG
WAVE TROUGH WILL DEVELOP OVER THE PLAINS DURING THE UPCOMING
WEEKEND...WITH THIS TROUGH PUSHING INTO THE GREAT LAKES AND OHIO
VALLEY BY NEXT TUESDAY.

ENSEMBLES SUGGEST A PRECIPITATION THREAT PRETTY MUCH ALL
PERIODS...WITH THE BEST THREAT BEING FROM SATURDAY NIGHT INTO SUNDAY
NIGHT WHEN THE MAIN SYSTEM ASSOCIATED WITH THE UPPER TROUGH MOVES
THROUGH. THERE MAY STILL BE ENOUGH RESIDUAL COLD AIR AROUND FOR
MIXED PRECIPITATION OVER PARTS OF THE AREA SATURDAY MORNING...BUT
ENSEMBLES INDICATE GENERALLY LIGHT QPF DURING THAT TIME. AS A
RESULT...SIGNIFICANT ACCUMULATIONS OF SNOW OR ICE NOT EXPECTED.

WEEKEND SYSTEM MAY BE QUITE DYNAMIC...WITH OPERATIONAL MODELS
SUGGESTING AN ASSOCIATED MID LEVEL JET IN EXCESS OF 100 KTS.

PRECIPITATION TYPE WILL TEND BACK TOWARDS SNOW BY MONDAY NIGHT AND
TUESDAY AS HEIGHTS LOWER WITH THE PASSAGE OF THE UPPER TROUGH. AT
THIS POINT...QPF LOOKS FAIRLY LIGHT.

&&

.AVIATION /DISCUSSION FOR THE 191200Z TAFS/...
ISSUED AT 532 AM EST WED NOV 19 2014

LAYERED CLOUDS ABOVE 050 EXPECTED ACROSS THE TAF SITES THIS MORNING
IN ADVANCE OF A FRONTAL SYSTEM. COLD ADVECTION IN THE WAKE OF THE
FRONTAL SYSTEM LATER THIS AFTERNOON WILL RESULT IN THE DEVELOPMENT
OF LOWER CEILINGS 030-040 BY THAT TIME. POTENTIAL FOR SCATTERED SNOW
SHOWERS TO DEVELOP NEAR AND IN THE POST FRONTAL ZONE...WITH
ASSOCIATED BRIEF VISIBILITY RESTRICTIONS. HOWEVER...EXPECTED
POTENTIAL/COVERAGE TOO LOW TO MENTION AT THIS TIME.

SURFACE WINDS EXPECTED TO INCREASE AFTER SUNRISE...WITH GUSTS 25-30
KTS FAIRLY COMMON BY MIDDAY AND INTO THE AFTERNOON HOURS. WIND
DIRECTION INITIALLY 160-180 DEGREES EARLY THIS MORNING SHOULD
GRADUALLY VEER WITH TIME TO 240-260 DEGREES BY LATE AFTERNOON.

&&

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

&&

$$

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

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