Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 012349
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
649 PM EST SUN FEB 1 2015

.SYNOPSIS...
ISSUED AT 355 PM EST SUN JAN 31 2015

LOW PRESSURE WILL MOVE NORTHEAST THROUGH SOUTHERN INDIANA TODAY
AND INTENSIFY. THE LOW WILL PUSH INTO CENTRAL PENNSYLVANIA BY
MONDAY MORNING. AS THIS MAJOR WINTER STORM CONTINUES...EXPECT
MODERATE TO HEAVY SNOW TO CONTINUE INTO THE EVENING. THEN
INCREASING WINDS WILL CREATE BLOWING AND DRIFTING SNOW FOR MUCH OF
THE REGION THROUGH TONIGHT. TRAVEL WILL BECOME DIFFICULT TO
IMPOSSIBLE ACROSS MOST OF THE REGION THROUGH TONIGHT. SNOW WILL
DIMINISH THEN END FROM WEST TO EAST BY LATE TONIGHT AS THE SYSTEM
PULLS OFF TO THE EAST. SOME LINGERING LIGHT LAKE EFFECT SNOW
SHOWERS ARE POSSIBLE ACROSS SOUTHWEST LOWER MICHIGAN AND NORTHWEST
INDIANA ON MONDAY. ANOTHER SYSTEM MAY BRING ADDITIONAL...BUT
LESSER SNOW ACCUMULATIONS TO PORTIONS OF THE SOUTHERN GREAT LAKES
REGION TUESDAY NIGHT INTO EARLY WEDNESDAY.

&&

.UPDATE...
ISSUED AT 630 PM EST SUN FEB 1 2015

ONLY MINOR CHANGES IN EARLY EVE UPDATE. TEMPS SFC AND ALOFT WERE
RUNNING A LITTLE HIGHER THAN FCST ACROSS FAR SERN PORTION OF CWA
ALLOWING PRECIP TO CHANGE TO RAIN IN THAT AREA. AS SFC LOW OVER
CENTRAL INDIANA MOVES EAST THIS EVE... CAA WILL OVERSPREAD THAT AREA
ALLOWING MIXED PRECIP TO CHANGE TO ALL SNOW. THIS ADJUSTMENT
REQUIRED SLIGHT LOWERING OF SNOWFALL AMOUNTS IN THAT AREA
OVERNIGHT... BUT WITH INCRSG WINDS/FALLING TEMPS... WINTER STORM
WARNING STILL JUSTIFIED THOUGH STORM TOTALS MAY BE BLO 6 INCHES THERE.

MOST OF THE REST OF THE CWA IN THE MIDST OF A MAJOR WINTER STORM.
DRY SLOT WAS EVIDENT ON WATER VAPOR PUSHING INTO NWRN INDIANA
WHICH SHOULD MOVE EAST ACROSS THE CWA THIS EVE... AT LEAST LOWERING
INTENSITY OF THE SNOW. THIS SHOULD BE FOLLOWED BY DEFORMATION/WRAP
AROUND SNOWFALL OVERNIGHT... BUT AGAIN INTENSITY OF THIS SHOULD BE
LIGHTER THAN WHAT WAS EXPERIENCED OVER THE PAST 8HRS. IN THE WAKE
OF THE SFC LOW MOVG EAST FROM CENTRAL INDIANA... WINDS WILL BE PICKING
UP CAUSING CONSIDERABLE BLOWING AND DRIFTING SNOW MAKING TRAVEL
VERY DIFFICULT AND IN SOME CASES IMPOSSIBLE.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 351 PM EST SUN FEB 1 2015

LEAVING ONGOING WSW AND REMAINING AMOUNTS/SENSIBLE WX LARGELY IN
TACT. TREMENDOUS /UPWARDS OF 250 PERCENT OF NORMAL PWAT TAP
POIGNANTLY DEPICTED BY RUC14 I290K SFC WITH 50-60 KT ASCENDING
JETLET INTO FAR SRN IN ATTM. MESOBANDING TODAY HAS BEEN QUITE
MODULATED AND TRANSITORY IN NATURE...SO WHILE A FEW SPOTS IN
HEAVIEST BAND MAY EXCEED 15 INCHES...DONT ANTICIPATE A LARGE
NUMBER OF OUTLIERS. CONTRAST TO GRANT/BLACKFORD AND JAY
COUNTIES...ESPECIALLY THEIR SRN HALVES...LESSER AMOUNTS OWING TO
WARM PROFILES/EARLIER MIXED PRECIP TO LIKELY YIELD AT/JUST BELOW
FINAL ACCUMS.

BOTH PRESENCE OF TROWAL THIS EVENING AND INCREASED STATIC
STABILITY PER RUC/NAM PROFILES SHOULD ALSO PRECLUDE MOD-EXTREME
CONVECTIVE ELEMENTS. STILL MOD/OCNL HEAVY SNOW ASSOCD WITH STORM
RELATIVE ISENTROPIC LIFT THROUGH EARLY TONIGHT...THEN QUICKLY
BECOMING PARALLEL TO SFCS FROM WEST TO EAST IN 06-12 UTC MON PD.
BY AND LARGE NRN IL TO ERN IA PRIMARY MID LEVEL DEFORMATION AXIS
WITHIN 700-600MB LAYER TO CONGEAL WITH ANOTHER RAPIDLY NEWD MOVG
MAXIMA EMANATING FM CNTL IL...NOW INTO NERN IL/NWRN IN TO TRACK
THROUGH SWRN LWR MI. PRIMARY AXIS THROUGH EARLY TONIGHT THEN
ALIGNS WITHIN MID LEVEL COL FROM KLAN TO KBMI BY 04 UTC THEN SRN
TAIL DEFORMATION BAND QUICKLY SWEEPS CWA PROVIDING LAST POTNL FOR
ACCUM SNOWFALL...THOUGH WITH THINNING/DESCENDING DGZ APPROACHING
SFC...THE DEPLETION OF MID LVL MOISTURE WITH PASSAGE OF DRY
SLOT...AND THE RELAXING UVM PROFILES...SUGGESTS OVERALL RATES
ANTICIPATED TO BE INCREASINGLY MUTED IN W-E FASHION ACRS CWA IN
03-08 UTC TIMEFRAME. FINAL SHORT/NEAR TERM ISSUE DEALS WITH BLSN
THAT SHOULD INCREASE ACRS ENTIRE CWA AS SLR INCREASE TO NEAR 15
TO 1 IN LATTER PART OF EVENT. RAMPING/BACKING FROM NORTHEAST TO
EAST AS SFC LOW CONTS TO DEEPEN AT APPROX RATE OF
1MB/2HRS...TRACKING ALONG I70 CORRIDOR THEN TO WCNTL PA BY
DAYBREAK. QUASI-STEADY MAINTENANCE OF 10-12MB/3HR CROSS
ISALLOBARIC DIFFERENCES TO BRING WIND GUSTS TO 20-30 MPH...AND
WHILE SUB BLIZZARD CONDS EXPECTED...CERTAINLY BLSN TO SUPPLANT
+SN AS THE MOST SIGNIFICANT HAZARD/IMPACT THROUGH THE NIGHT. MOST
CONCERN WITH E-W OPEN AREA/RURAL/COUNTY ROADS TO BE IMPACTED AS
SFC WINDS PROGRESSIVELY BACK.

&&

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 351 PM EST SUN FEB 1 2015

AS ONE SYSTEM IS DEPARTING THE NEXT WILL BE QUICKLY MOVING IN
FROM THE NORTHWEST TO BRING ANOTHER CHANCE FOR LIGHT SNOW TO
MAINLY NORTHERN PORTIONS OF THE FORECAST AREA (ALONG AND NORTH OF
ROUTE 30). FEW CHANGES HAVE BEEN MADE AS OVERALL TIMING AND TRACK
SEEM TO BE REASONABLE WITH A SWATH OF AN INCH OR 2 OF SNOW
EXPECTED NORTH OF 30 AND DUSTING TO AT MOST AN INCH SOUTH. COLDER
AIR WILL MOVE BACK IN AGAIN BEHIND THE SYSTEM...BUT ONLY BE A
GLANCING BLOW WITH HIGHS DROPPING FROM THE 20S TUES/WEDS INTO THE
TEENS ON THURSDAY BEFORE HEADING BACK INTO THE 20S. LAKE RESPONSE
EXPECTED BEHIND THIS SYSTEM WITH MORE OF A MULTI BAND SETUP.
COULD BE SOME LOCAL ACCUMULATIONS BUT SHOULDN`T BE ANYTHING
SIGNIFICANT.

A WEAK TROUGH WILL MOVE FROM THE WEST COAST ON FRI NGT INTO SAT
AND MOVE RAPIDLY TOWARDS THE AREA BY SUNDAY. A COLD FRONT WILL
DROP SOUTH WHICH MAY BRING ADDITIONAL CHANCES FOR LIGHT SNOW. CHC
POPS WARRANTED AT THIS POINT OVER THE WEEKEND. BELOW NORMAL
TEMPERATURES EXPECTED THROUGH THE LATTER HALF OF THE WEEK INTO
THE WEEKEND.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 630 PM EST SUN FEB 1 2015

IFR/LIFR CONDITIONS SHOULD GRDLY IMPROVE OVERNIGHT AS LOW OVER
CENTRAL INDIANA MOVES EAST. WINDS WILL BE INCREASING CAUSING
BLOWING AND DRIFTING SNOW. WINDS WILL DIMINISH AND BACK TO NW
MONDAY WHICH SHOULD RESULT IN LAKE EFFECT MVFR CIGS PERSISTING
WITH SOME LAKE EFFECT SHSN AT SBN.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER STORM WARNING UNTIL 4 AM EST /3 AM CST/ MONDAY FOR
     INZ003>009-012>018-020-022>027-032>034.

MI...WINTER STORM WARNING UNTIL 7 AM EST MONDAY FOR MIZ081.

     WINTER STORM WARNING UNTIL 4 AM EST MONDAY FOR MIZ077>080.

OH...WINTER STORM WARNING UNTIL 7 AM EST MONDAY FOR OHZ001-002-004-
     005-015-016-024-025.

LM...NONE.
&&

$$

UPDATE...JT
SYNOPSIS...MURPHY
SHORT TERM...MURPHY
LONG TERM...FISHER
AVIATION...JT


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