Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 240936
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
536 AM EDT FRI APR 24 2015

.SYNOPSIS...
ISSUED AT 500 AM EDT FRI APR 24 2015

CONDITIONS FAVORABLE FOR FROST AND FREEZING CONDITIONS EARLY
THIS MORNING WILL PREVAIL WITH HIGH PRESSURE OVER THE GREAT LAKES.
THE COLDEST TEMPERATURES WILL BE OVER FAR SOUTHWEST LOWER MICHIGAN
AND INTO ADJACENT AREAS OF NORTHERN INDIANA AND NORTHWEST OHIO.
LOWS OVER THESE AREAS WILL DROP WELL DOWN INTO THE 20S. AS THE
HIGH MOVES TO THE MID ATLANTIC REGION LATER TODAY...A LOW PRESSURE
AREA WILL EMERGE FROM THE CENTRAL PLAINS AND SPREAD WIDESPREAD
RAIN TO THE AREA ON SATURDAY. HIGHS TODAY WILL AGAIN BE COOLER
THAN NORMAL...REACHING 55 TO 60 DEGREES. LOWS TONIGHT WILL BE MUCH
WARMER THAN THIS PAST NIGHT WITH TEMPERATURES AROUND 40 TO 45.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 438 AM EDT FRI APR 24 2015

AN EXCEPTIONALLY DRY AIRMASS WAS OVER THE REGION ALLOWING EARLY
MORNING TEMPERATURES TO DROP INTO THE 20S AT MANY LOCATIONS. HAVE
KEPT THE FREEZE WARNING OUT UNTIL 9AM. THE SHALLOW BUT STEEP
RADIATION INVERSION SHOULD MIX OUT RATHER QUICKLY AND WITH FULL
SUN...SHOULD ALLOW TEMPERATURES TO RISE WELL INTO THE 50S TO AROUND
60 DEGREES. TRENDED HIGHS A LITTLE WARMER TODAY FAVORING THE GFS
WHICH HAS VERIFIED BETTER THAN THE NAM/MET WITH RETREATING COLD
AIRMASSES. CLOUDS WILL BEGIN INCREASING LATER TODAY...WITH SKIES
BECOMING CLOUDY BY EARLY TONIGHT AS THE SURFACE LOW MOVES NORTHEAST
TOWARD THE AREA. KEPT CHANCES OR RAIN OVERNIGHT LIMITED TO THE
SOUTHWEST HALF OF THE FORECAST AREA IN LINE WITH THE LATEST
GFS/BUFKIT. ALTHOUGH MID LEVEL MOISTURE INCREASES RAPIDLY BY LATE
THIS AFTERNOON...IT IS LIKELY TO TAKE SOME TIME UNTIL LIFT IS DEEP
ENOUGH TO SUPPORT PRECIPITATION.

&&

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 438 AM EDT FRI APR 24 2015

UPR LOW OVER THE SWRN U.S. IS EXPECTED TO MOVE ENE INTO THE MID
MS/LWR OH VALLEY SATURDAY. SYSTEM SHOULD UNDERGO SOME WKNG SATURDAY
IN RESPONSE TO SHEARING AS IT ENCOUNTERS NW WINDS ON WRN PERIPHERY
OF DEEP NRLY STNRY LOW OVER NEW ENGLAND/NOVA SCOTIA. MODELS CONT TO
SUGGEST DECENT LOW LEVEL THETA-E ADVECTION/CONVERGENCE MOVG INTO OUR
AREA SATURDAY ON THE NOSE OF A 50KT S-SW LLJ IN ADVANCE OF THE
LOW... WITH LIFT FURTHER ENHANCED BY MID LEVEL SHRTWV LIFTING NE
ACROSS OUR AREA AHEAD OF MAIN CIRCULATION. DESPITE THESE FAVORABLE
FACTORS... SUSPECT NAM/GFS QPF ARE OVERDONE AS BULK OF INSTABILITY
REMAINS OVER SRN IN/OH... THUS LEANED TOWARD LOWER ECMWF RAINFALL
AMOUNTS WITH STORM TOTALS RANGING FROM UNDER A QUARTER INCH FAR NE
TO NEAR 3/4" SW. RAIN/CLOUDS SHOULD HOLD TEMPS MAINLY IN THE 40S
SATURDAY. RAIN SHOULD TAPER OFF FROM NW-SE ACROSS THE AREA SAT EVE
AS THE WKNG LOW MOVES EAST TO THE MID ATLANTIC STATES. WK CAA IN
WAKE OF THIS SYSTEM SHOULD RESULT IN LOWS SATURDAY NIGHT IN THE 30S.
LOW EXPECTED TO STRENGTHEN AGAIN OVER THE WRN ATLANTIC SUN-MON
DEEPENING CLOSED UPR LOW OFF THE NEW ENGLAND COAST ALLOWING HIGH
PRESSURE RIDGE BEHIND IT TO BUILD VERY SLOWLY EAST INTO THE WRN
GRTLKS DURING THIS TIMEFRAME PROVIDING FAIR BUT COOL WX IN OUR AREA
WITH HIGHS IN THE M-U50S AND LOWS IN THE M-U30S.

MEDIUM RANGE MODELS CONT TO SUGGEST TROF MOVG INTO THE PAC NW TODAY
WILL DIG INTO THE SWRN U.S. AND CUT-OFF EARLY NEXT WEEK BUT CONT TO
PROGRESS SLOWLY EAST ACROSS THE LWR MS VALLEY AND INTO THE SERN
CONUS MID-WEEK...MERGING WITH A SHRTWV DROPPING SE FROM CENTRAL
CANADA CARVING A DEEP TROF AGAIN OVER THE ERN CONUS LATE NEXT WEEK.
HWVR MODELS CONT TO HAVE SGFNT DIFFERENCES IN TIMING/LOCATION OF
THIS TROF AND POOR RUN-RUN CONTINUITY WITH LATEST GFS CONSIDERABLY
FARTHER WEST WITH THE UPR TROF WITH ASSOCIATED COOLER TEMPS THAN
INDICATED BY THE ECMWF. GIVEN UNCERTAINTY... STAYED CLOSE TO 00Z
MODEL BLEND  WITH DRY CONDITIONS AND TEMPS NEAR NORMAL FCST FOR
WED-THU.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 523 AM EDT FRI APR 24 2015

VFR CONDITIONS SHOULD PREVAIL THIS ENTIRE PERIOD AS THE SURFACE
RIDGE MOVES EAST AND A LOW PRESSURE AREA MOVES TOWARD THE REGION.
AN EXCEPTIONALLY DRY AIRMASS TO START OUT WITH WILL BEGIN TO
SATURATE WITH SKIES BECOMING CLOUDY...HOWEVER...ANY PRECIPITATION
SHOULD HOLD OFF UNTIL AFTER THE END OF THE TAF PERIOD.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...FREEZE WARNING UNTIL 9 AM EDT /8 AM CDT/ THIS MORNING FOR
     INZ003>009-012>018-020-022>027-032>034.

MI...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR MIZ077>081.

OH...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR OHZ001-002-004-
     005-015-016-024-025.

LM...NONE.
&&

$$

SYNOPSIS...MURPHY/SKIPPER
SHORT TERM...SKIPPER
LONG TERM...JT
AVIATION...SKIPPER


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