Area Forecast Discussion
Issued by NWS Indianapolis, IN

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000
FXUS63 KIND 262021
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
320 PM EST WED NOV 26 2014

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

&&

.SYNOPSIS...
ISSUED AT 250 PM EST WED NOV 26 2014

A CLIPPER SYSTEM WILL BRING CHANCES FOR SNOW TO MAINLY SOUTHWESTERN
SECTIONS OF CENTRAL INDIANA TONIGHT. WARMER AIR WILL RETURN TO THE
AREA THIS WEEKEND ALONG WITH CHANCES FOR RAIN. A COUPLE OF COLD
FRONTS WILL KEEP CHANCES FOR RAIN AT TIMES EARLY NEXT WEEK...BUT
TEMPERATURES WILL BE SEASONABLE.

&&

.NEAR TERM.../REST OF THIS AFTERNOON AND TONIGHT/
ISSUED AT 250 PM EST WED NOV 26 2014

ONE AREA OF LOW CLOUDS SHOULD CONTINUE TO CLEAR OUT TO THE
NORTHEAST...BUT CLOUDS ASSOCIATED WITH AN APPROACHING CLIPPER SYSTEM
WILL QUICKLY INCREASE FROM THE WEST BY LATE AFTERNOON.

THE CLIPPER SYSTEM AND ASSOCIATED UPPER TROUGH WILL WEAKEN AS THEY
MOVE SOUTHEAST INTO THE OHIO VALLEY TONIGHT. Q-VECTOR CONVERGENCE
PLOTS SHOW DECENT FORCING...BUT MOST OF THE FORCING WILL BE TO THE
SOUTH OF THE FORECAST AREA.

MOISTURE IS LIMITED TO THE NORTH OF THE SYSTEM...AND THERE WILL BE A
SHARP CUT-OFF TO THE PRECIPITATION. BASED ON LATEST TRENDS AND SHORT
TERM MODEL FORECASTS...HAVE DECIDED TO CONFINE POPS TONIGHT TO THE
SOUTHWEST THIRD OR SO OF THE FORECAST AREA.

WENT LIKELY POPS ACROSS THE EXTREME SOUTHWEST QUICKLY TAPERING TO
SLIGHT CHANCE POPS TO THE NORTHEAST. POPS WILL DIMINISH AFTER LATE
EVENING AS THE SYSTEM MOVES OFF TO THE EAST.

FORECAST SOUNDINGS SHOW MOST OF THE COLUMN BELOW FREEZING WITH ONLY
THE NEAR SURFACE LAYER ABOVE FREEZING. WENT MAINLY SNOW FOR THE
PRECIPITATION TYPE...BUT DID INCLUDE A POSSIBLE MIX WITH RAIN ACROSS
THE FAR SOUTHWEST EARLY TONIGHT TO ACCOUNT FOR THE INITIALLY WARM
AIR. ANY ACCUMULATION SHOULD REMAIN BELOW 1 INCH...WITH HIGHEST
AMOUNTS IN THE EXTREME SOUTHWEST FORECAST AREA.

OTHERWISE WENT WITH A MODEL BLEND FOR LOW TEMPERATURES UNDER MOSTLY
CLOUDY SKIES. THESE TEMPERATURES ARE NEAR MOS VALUES.

&&

.SHORT TERM.../THANKSGIVING THROUGH SATURDAY/
ISSUED AT 250 PM EST WED NOV 26 2014

FOCUS IS ON ANY CHANCE FOR PRECIPITATION THROUGH THE PERIOD. IN
GENERAL MODELS ARE CLOSE ENOUGH THAT A BLEND CAN BE USED.

EARLY ON THANKSGIVING AN UPPER TROUGH WILL MOVE ACROSS THE LOWER
GREAT LAKES. SOME WEAK FORCING FROM THIS UPPER TROUGH COULD GENERATE
A FEW FLURRIES ACROSS THE EASTERN FORECAST AREA. DURING THE
AFTERNOON FLURRIES WILL REMAIN POSSIBLE ACROSS THE FAR NORTHEAST DUE
TO THE INFLUENCE OF LAKE MICHIGAN AS COLDER AIR FLOWS IN BEHIND THE
UPPER TROUGH.

SKIES LOOK TO BE MOSTLY CLOUDY DURING THE MORNING WITH PERHAPS SOME
PARTIAL CLEARING ACROSS THE SOUTHWEST FORECAST AREA AS DRIER AIR
TRIES TO WORK IN. FOR TEMPERATURES STUCK WITH A MODEL BLEND.

HIGH PRESSURE WILL MOVE IN THURSDAY NIGHT ENDING ANY FLURRIES. WITH
SOME PARTIAL CLEARING AND A COLD AIRMASS IN PLACE...READINGS SHOULD
DIP INTO THE TEENS IN MANY AREAS. HOWEVER DID NOT GO QUITE AS COLD
AS MAV MOS WOULD SUGGEST GIVEN SOME CLOUDS.

WARM ADVECTION ON LATE THURSDAY NIGHT INTO FRIDAY WILL INCREASE THE
CLOUDS ONCE AGAIN BUT MOISTURE IS LIMITED ENOUGH TO KEEP A DRY
FORECAST. STUCK WITH THE MODEL BLEND FOR TEMPERATURES.

BY SATURDAY A STRONG PUSH OF WARM AIR WILL MOVE INTO THE AREA ALONG
WITH INCREASING LOW LEVEL MOISTURE. FORCING LOOKS TOO WEAK FOR
ORGANIZED PRECIPITATION...BUT LOOKS LIKE THERE COULD BE ENOUGH LIFT
FOR SOME SPRINKLES BY SATURDAY AFTERNOON.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...

ISSUED AT 203 PM EST WED NOV 26 2014

GFS AND ECMWF CONTINUE TO SUGGEST A QUICK MOVING COLD FRONT TO
SWEEP ACROSS THE OHIO VALLEY ON LATE SATURDAY AND EARLY SUNDAY.
BEST FORCING REMAINS FAR NORTH OF INDIANA AND FLOW ALOFT APPEARS
ZONAL...THUS CONFIDENCE IN THIS EVENT IS LOW.

ECMWF THEN SHOWS HIGH PRESSURE BUILDING OUT OF THE UPPER MIDWEST
INTO THE OHIO VALLEY AT THE SURFACE WITH THE QUICK ZONAL FLOW
ALOFT INTO THE MIDDLE OF NEXT WEEK. A LINGERING SURFACE BOUNDARY
APPEARS TO STICK CLOSE TO THE OHIO RIVER ACCORDING TO THE GFS AND
THE RESULT IS SOME CHC POPS IN SUPERBLEND. AGAIN CONFIDENCE IN
PRECIP CONTINUES TO BE VERY LOW AS MOISTURE AND FORCING APPEAR
LACKING OVERALL.

FINALLY THE ECMWF AGAIN SUGGESTS ANOTHER MOISTURE STARVED COLD
FRONT WILL SWEEP INTO THE OHIO VALLEY ON TUESDAY NIGHT INTO
WEDNESDAY. AGAIN BEST FORCING APPEARS WELL NORTH OF THE GREAT
LAKES AND AGAIN CONFIDENCE IS LOW.

OF NOTE THROUGH THIS PERIOD OF THE FORECAST IS THE MOSTLY ZONAL
FLOW ALOFT...WHICH SHOULD LEAD TO NEAR NORMAL OR ONLY SLIGHTLY
BELOW NORMAL TEMPERATURES.

&&

.AVIATION /DISCUSSION FOR THE 262100Z IND TAF UPDATE/...

ISSUED AT 320 PM EST WED NOV 26 2014

UPDATED TO IMPROVE THE CEILING TO VFR THROUGH 01Z BASED ON SATELLITE
AND OB TRENDS.

PREVIOUS DISCUSSION FOLLOWS...

MVFR CONDITIONS ARE EXPECTED TO IMPROVE TO VFR LATE THIS AFTERNOON
AND EVENING...BEFORE RETURNING TO MVFR OVERNIGHT.

TWO DIFFERENT CLOUD FIELDS EFFECTING CENTRAL INDIANA AT THIS TIME.
MVFR CIGS OVER INDIANA WERE SLOWLY ADVECTING WEST AND ERODING.
MEANWHILE...A HIGHER VFR CLOUD DECK ASSOCIATED WITH THE LOW
PRESSURE SYSTEM OVER IOWA WAS PUSHING SOUTHEAST TOWARD THE TAF SITES.
THUS AS THE LOW CLOUDS CONTINUE TO ERODE AND THE VFR CIGS ARRIVE
FROM THE WEST WITH THE ARRIVAL OF THE PRESSURE SYSTEM A PERIOD OF
VFR CIGS WILL BE EXPECTED.

THE SURFACE LOW IS THEN EXPECTED TO PUSH SOUTH OF THE TAF SITES
TONIGHT TOWARD THE OHIO RIVER. THIS WILL PLACE THE TAF SITES IN
THE COLD SECTOR OF THE SYSTEM AND TIME HEIGHTS...FORECAST
SOUNDINGS AND OBS UPSTREAM SUGGEST MVFR CIGS AS THIS PASSES DUE TO
SATURATED LOWER LEVEL. FORCING AND MOISTURE REMAIN PROBLEMS FOR
THIS SYSTEM AND ANY PRECIP SHOULD BE QUITE LIMITED.

AS THE LOW DEPARTS OM THURSDAY MORNING FORECAST SOUNDINGS AND TIME
HEIGHTS CONTINUE TO KEEP MOISTURE LINGERING IN THE LOWER LEVELS
AMID SUBSIDENCE. THUS WILL TREND TOWARD MVFR CIGS THROUGH THE
MORNING HOURS.


&&

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

$$

SYNOPSIS...50
NEAR TERM...50
SHORT TERM...50
LONG TERM....PUMA
AVIATION...JP/MK

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