Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 250544
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1244 AM EST SUN JAN 25 2015

.SYNOPSIS...
ISSUED AT 1238 AM EST SUN JAN 25 2015

IT WILL BE CLOUDY OVERNIGHT WITH LOW TEMPERATURES RANGING FROM THE
MIDDLE 20S OVER MICHIGAN TO THE LOWER 30S OVER CENTRAL INDIANA AND
OHIO. A CLIPPER SYSTEM WILL APPROACH THE REGION EARLY SUNDAY
MORNING AND MOVE THROUGH THE OHIO RIVER VALLEY DURING THE DAY.
THIS WILL SPREAD ACCUMULATING SNOW OVER PARTS OF CENTRAL AND
NORTHERN INDIANA AND NORTHWEST OHIO WITH RAIN SOUTH OF THIS AREA.
HIGH TEMPERATURES SUNDAY WILL BE IN THE LOWER 20S NORTH TO UPPER
30S SOUTH.

.SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 357 PM EST
SAT JAN 24 2015

THE MAIN CHALLENGE THROUGH SUNDAY IS THE HANDLING OF THE CLIPPER TYPE
OF SYSTEM THAT WILL MOVE ACROSS THE REGION LATE TONIGHT AND SUNDAY.
OVERALL...THERE WAS STILL A LOT OF UNCERTAINTY WITH THE STRENGTH AND
TRACK OF THIS SYSTEM WITH MOST OF THE MODELS...ESPECIALLY FOR JUST
30 HOURS OUT FROM THE MODEL BASE TIME. THE GFS IS SLIGHTLY FAVORED
AT THIS TIME...MAINLY DUE TO RUN TO RUN CONSISTENCY AND EARLY
VERIFICATION. THE 290K ISENTROPIC SURFACE PER GARCIA METHOD SUGGESTS
3-6 INCHES OVER NRN INDIANA AND NW OHIO...WITH LESSER AMOUNTS OVER
FAR SOUTHERN LOWER MICHIGAN. A CAVEAT IS THE STRENGTH AND THE TRACK
OF THE TROWAL WHICH SHOULD ALLOW FOR DECENT SNOWFALL. SO FOR THIS
PACKAGE...AND AFTER COORDINATION WITH SURROUNDING OFFICES...
CONTINUED WITH THE PREVIOUS SNOWFALL FORECAST OF 3 TO 5 INCHES OVER
NRN INDIANA AND NW OH...AND 2 TO 4 INCHES OVER FAR SOUTHERN LOWER
MICHIGAN. LOCAL SNOWFALL AMOUNTS OF 6 INCHES ARE POSSIBLE UNDER THE
TROWAL.


&&

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 357 PM EST SAT JAN 24 2015

SNOW SHOULD BE IN THE PROCESS OF ENDING ACROSS THE CWA AT START OF
THE PERIOD SUNDAY EVE AS STRONG CLIPPER SYSTEM MOVES SE FM KY TO NC
OVERNIGHT.  BRISK NE-N WINDS ON BACKSIDE OF THE LOW SUNDAY EVE MAY
CAUSE SOME DRIFTING SNOW... BUT WINDS WILL DIMINISH OVERNIGHT AS LOW
PULLS AWAY AND RIDGE APPROACHES ALLOWING TIME TO CLEAR ANY DRIFTED
RURAL ROADS BY MONDAY MORNING RUSH. CLOUD COVER SHOULD ALSO DIMINISH
OVERNIGHT BUT RIDGE REMAINS TO OUR WEST... SO FULL BOUNDARY LAYER
DECOUPLING PRBLY WON`T OCCUR... STILL WITH FRESH SNOW COVER TEMPS
SHOULD FALL TO BLO NORMAL WITH LOWS IN THE 5-15F RANGE... COLDEST
N-NE WHERE CLEARING OCCURS EARLIEST.

NEXT SHRTWV TO TOP WRN RIDGE AND DROP SEWD FROM WRN CANADA THROUGH
THE MS/OH VALLEY MON-TUE STILL EXPECTED TO BE QUITE WEAK/SHEARED
OUT. PREFER GEM/ECMWF SOLUTIONS WHICH HAVE A MORE WESTERLY TRACK AND
WEAKEN SHRTWV FASTER THAN NAM/GFS/SREF... BUT MAINTAINED LOW POPS
MON NGT-TUE DUE TO STILL SOME SUPPORT FROM THE AMERICAN MODELS. ALSO
PER ECMWF... LIGHT MAINLY N-NE FLOW IN THIS TIMEFRAME AND PRESUMABLY
SOME SNOW COVER OVER OUR CWA AND UPSTREAM ACROSS LWR MI... LEANED
TOWARD COOLER ECMWF MOS TEMPS.

WESTERN NORTH AMERICA RIDGE EXPECTED TO WEAKEN AND MOVE EAST INTO
OUR AREA WEDNESDAY AS CUT-OFF LOW OFF BAJA AND NE PACIFIC SHRTWV AND
MERGE AND MOVE EAST INTO THE PLAINS. MEDIUM RANGE MODELS HAVE
TRENDED A LITTLE DEEPER WITH MORE GULF MOISTURE ADVECTING NORTHWARD
INTO OUR AREA AHEAD OF THIS SYSTEM... SO PRECIP CHANCES INCREASING
FOR THU. H85 TEMPS PROGGED TO RISE TO NEAR OR ABOVE 0C... SO
RAIN/SNOW MAINTAINED FOR PTYPE ATTM. CAA IN THE WAKE OF THIS
LOW SHOULD SEND TEMPS BACK BLO NORMAL BY FRIDAY.

ECMWF HAS BEEN CONSISTENT INDICATING A DEEPENING UPR LEVEL TROF WILL
DEVELOP OVER EASTERN NORTH AMERICA BY NEXT WEEKEND WITH A STRONG
SHRTWV/ARCTIC FRONT DROPPING SEWD INTO THE UPR GRTLKS ON SATURDAY.
12Z GFS HAS BACKED OFF ON THIS SCENARIO... AT LEAST THROUGH THIS
FCST PERIOD... SHUNTING SATURDAY`S ARCTIC SURGE OFF TO OUR NE.
PREFER MORE CONSISTENT ECMWF FCST AND INTRODUCED A CHC OF SNOW ON
DAY7 WITH TEMPS NEAR NORMAL AHEAD OF ARCTIC AIR FRONT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1236 AM EST SUN JAN 25 2015

MVFR CIGS WERE ACROSS THE TAF SITES AT ISSUANCE BUT CONDITIONS
WERE HIGHLY VARIABLE WITH MUCH OF WEST CENTRAL AND NORTHWEST
INDIANA BEING VFR. AN AREA OF LOCAL VIS BELOW 1SM BR WAS
DEVELOPING AROUND KVPZ. HIRES GUIDANCE ACTUALLY CAPTURES THIS
SMALL AREA AND EXPANDS IT EAST TOWARD KSBN OVERNIGHT. WILL HAVE TO
MONITOR BUT DID INTRODUCE MVFR VIS TO KSBN. CLIPPER SYSTEM TO
DIVE EVEN FURTHER SOUTH NOW WITH SFC LOW MOVING OVER KEVV TODAY.
HEAVIER SNOWFALL WILL BE SOUTH OF TERMINALS BUT STILL EXPECT TO
SEE LIGHT SNOW FROM LATE MORNING TO EARLY EVENING WITH IFR AT KSBN
AND LIFR STILL POSSIBLE AT KFWA.

&&

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

$$

SYNOPSIS...LASHLEY
SHORT TERM...SKIPPER
LONG TERM...JT
AVIATION...LASHLEY


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