Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 241823
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
223 PM EDT FRI APR 24 2015

.SYNOPSIS...
ISSUED AT 933 AM EDT FRI APR 24 2015

DRY CONDITIONS AND MOSTLY SUNNY TO PARTLY CLOUDY SKIES ARE
EXPECTED TODAY. WIDESPREAD RAIN IS EXPECTED ACROSS THE AREA ON
SATURDAY. HIGHS TODAY WILL AGAIN BE COOLER THAN NORMAL...REACHING
55 TO 60 DEGREES. LOWS TONIGHT WILL BE AROUND 40 TO 45 DEGREES.

&&

.UPDATE...
ISSUED AT 1200 PM EDT FRI APR 24 2015

NO MAJOR CHANGES PLANNED TO FORECAST AT THIS TIME. HIGH/MID CLOUDS
WILL BEGIN TO INCREASE FROM THE WEST/SOUTHWEST THIS AFTERNOON AS
LOW/MID LEVEL WAA CONTINUES TO RAMP UP. SUBCLOUD LAYER WILL REMAIN
VERY DRY HOWEVER THROUGH EARLY THIS EVENING. BULK OF GUIDANCE
CONTINUES TO SUGGEST NARROW LOW LEVEL FGEN INDUCED BAND OF LIGHT
RAIN IN ASSOCIATION WITH NEXT UPPER LEVEL SHORT WAVE TRACKING OUT
OF SOUTHERN IOWA. CONFIDENCE REMAINS LOW IN MEASURABLE PRECIP THIS
EVENING GIVEN MOISTURE CONSIDERATIONS. PREVIOUSLY FORECASTED TEMPS
STILL APPEAR REASONABLE AND NO SIGNIFICANT CHANGES ANTICIPATED AT
THIS TIME FOR THIS AFTERNOONS FORECAST.

&&

.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 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 213 PM EDT FRI APR 24 2015

MID/UPPER LEVEL RIDGING IN ADVANCE OF UPPER LEVEL WAVE KICKING OUT
OF THE ROCKIES HAS ALLOWED FOR QUIET CONDITIONS TO CONTINUE TODAY.
AN UPPER LEVEL SHORT WAVE TROUGH WILL CONTINUE TO TRACK ACROSS
IOWA/SOUTHERN WISCONSIN THROUGH LATE AFTERNOON. A ZONE OF WEAK LOW
LEVEL MOISTURE POOLING WITH THIS WAVE MAY BRING SOME SCATTERED
LIGHT RAIN SHOWERS OR SPRINKLES TO EXTREME NORTHERN
INDIANA/SOUTHERN LOWER MICHIGAN THIS EVENING. OTHERWISE...GREATEST
CHANCES FOR RAIN THIS PERIOD WILL BE TOWARD MID MORNING SATURDAY
INTO SATURDAY AFTERNOON AS PRIMARY UPPER LEVEL TROUGH WORKS INTO
THE MID MS VALLEY. A TREND TO MVFR CONDITIONS IS EXPECTED TOWARD
THE END...OR JUST AFTER THIS FORECAST PERIOD. LIGHT WEST/SOUTHWEST
WINDS THIS AFTERNOON WILL BECOME LIGHT AND VARIABLE FOR A SHORT
TIME...AND THEN EASTERLY TONIGHT AS SFC LOW PRESSURE TRACKS
SOUTHWEST OF THE LOCAL AREA.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

UPDATE...MARSILI
SYNOPSIS...NG
SHORT TERM...SKIPPER
LONG TERM...JT
AVIATION...MARSILI


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