Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 240548
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1248 AM EST TUE FEB 24 2015

.SYNOPSIS...
ISSUED AT 431 PM EST MON FEB 23 2015

A QUIET BUT COLD NIGHT IS IN STORE FOR THE AREA. LOW TEMPERATURES
WILL RANGE FROM 4 BELOW TO 2 ABOVE. WIND CHILL VALUES WILL RANGE
FROM 10 TO 20 BELOW ZERO BY TUESDAY MORNING. A LOW PRESSURE SYSTEM
WILL MOVE NORTH OF THE REGION TUESDAY...BRINGING GUSTY SOUTHWEST
WINDS AND LIGHT SNOW. THE STRONG WINDS WILL LEAD TO AREAS OF
BLOWING AND DRIFTING SNOW...WHICH WILL GREATLY REDUCE
VISIBILITIES...ESPECIALLY ON EAST-WEST ROADS. CONDITIONS WILL BE
WORST NORTH OF US 6. SEE THE LATEST WINTER WEATHER MESSAGE FOR
DETAILS.

&&

.UPDATE...
ISSUED AT 730 PM EST MON FEB 23 2015

LOW LEVEL ANTICYCLONE TO SHIFT SOUTHWARD TONIGHT ALLOWING FOR
STRONGER SOUTHWESTERLY LOW LEVEL HEIGHT GRADIENT TO BECOME
ESTABLISHED. BEFORE THIS OCCURS...SEVERAL MORE HOURS OF STRONG
RADIATIONAL COOLING ARE EXPECTED THIS EVENING. LATEST
OBSERVATIONAL TRENDS SHOW SHARPLY FALLING TEMPERATURES PARTICULARLY
EASTERN PORTIONS OF THE AREA AND EXTENDING IN WEST CENTRAL OHIO.
TEMPS MAY ACTUALLY BOTTOM OUT DURING THE EARLY PORTIONS OF THE
OVERNIGHT HOURS BEFORE THIS STRONGER GRADIENT BECOMES
ESTABLISHED. SOME INCREASING HIGH CLOUD COVER IS ALSO
EXPECTED...BUT PARTICULARLY FOR NORTHERN AREAS. WHILE TEMPS MAY
BE STEADY OR EVEN SLOWLY RISING AFTER 10Z...WOULD SUSPECT THE
INCREASE IN WIND SPEEDS WILL PARTIALLY OR COMPLETELY OFFSET THIS
TREND IN TERMS OF WIND CHILLS. GIVEN LATEST OBSERVATIONAL TRENDS
AND WIND FORECAST OVERNIGHT...WILL GO AHEAD AND ISSUE A WIND CHILL
ADVISORY ACROSS NORTHEAST INDIANA AND NORTHWEST OHIO PORTIONS OF
CWA FOR LOCATIONS NOT CURRENTLY IN THE WINTER WEATHER ADVISORY FOR
EARLY TUESDAY MORNING FOR WIND CHILLS AS COLD AS 15 TO 20 BELOW.
WILL HOLD OFF ON THE ADVISORY FOR EXTREME SOUTHWEST LOCATIONS
GIVEN POSSIBILITY OF A SHARPER RISING TEMP TREND TOWARD MORNING.
UPDATED ZFP/WSW WILL BE ISSUED BY 01Z.

&&

.SHORT TERM...(THIS EVENING THROUGH TUESDAY)
ISSUED AT 307 PM EST MON FEB 23 2015

ARCTIC RIDGE CNTRD OVR WRN IL THIS AFTN WILL CONT WILL SLIDE EWD
INTO THE MID ATL COAST BY TUE AM AHD OF APCHG SFC TROUGH ASSOCD/W
VIGOROUS NRN STREAM SW TROUGH AMPLIFYING THROUGH THE NRN LAKES.
ROBUST SWRLY LL FLW XPCD TO DVLP INBTWN AS 200M+ HFC PASSES THROUGH
NRN LWR MI BY MIDDAY TUE. SRN EXTENT OF BTR HGT FALLS AND H7 MSTR
PLUME SHLD AIDE IN DVLPMNT OF A PD OF LIGHT SNOW ALG SEWD ADVG SFC
TROUGH AND HAVE EXPANDED POPS A BIT TUE AFTN.

OTRWS RAPIDLY ESCALATING SFC GRADIENT LIKELY TO CAUSE PROBS MID
MORNING THROUGH LT AFTN W/BLOWING SNOW POTENTIAL AS MIXED LYR HGTS
PK NR 900MB...ESP IN LIGHT OF SIG SNOWPACK PRESENT ALG/NORTH OF
THE HIGHWAY 6 CORRIDOR. AND AFT COORD WILL ISSUE A WINTER WX
ADVISORY TO INCLUDE NRN TIER OF IN COUNTIES AND SRN MI PRIMARILY
DRIVEN BY BLOWING SNOW POTENTIAL YET CAN NOT DISCOUNT POTENTIAL
SNOW ACCUMS OF 1 TO 2 INCHES WHICH WILL GREATLY EXACERBATE
POTENTIAL VISBY RESTRICTIONS TUE AFTN.

&&

.LONG TERM...(TUESDAY NIGHT THROUGH MONDAY)
ISSUED AT 307 PM EST MON FEB 23 2015

THE MID-LATE WEEK PERIOD WILL FEATURE MAINLY DRY/COLD CONDITIONS AS
POSITIVE PNA UPPER RIDGE ALONG THE WEST COAST HOLDS DEEP EASTERN
CONUS TROUGHING IN PLACE. SURE...THERE MAY BE SOME LIGHT LAKE
EFFECT SHSN ACROSS NW FLOW BELTS WED NIGHT THRU THU NIGHT...AND
POSSIBLY A FEW SYNOPTIC FLURRIES/-SHSN WED NIGHT-THU AM WITH THE
NEXT VORT LOBE/TROUGH DROPPING SE FROM CANADA...BUT NOTHING REALLY
EXPECTED TO ADD UP OR CREATE SIG TRAVEL DISRUPTIONS.

SURFACE HIGH PRESSURE BUILDS IN FOR FRI-SAT IN TRANSITION TO A
RETROGRADING POSITIVELY TILTED WESTERN US TO NORTHERN HIGH PLAINS
UPPER TROUGH. DEEPENING/PERTURBED SOUTHWEST FLOW DOWNSTREAM WILL
LIKELY SEND A DECENT SURGE OF MOISTURE AND INCREASING MID-UPPER JET
SUPPORT OVER RETREATING ARCTIC WEDGE BY LATER SAT NIGHT-SUN-MON
AM...WITH PCPN LIKELY BLOSSOMING INVOF AN ASSOCIATED BAROCLINIC ZONE
FROM THE PLAINS EAST TO THE OH VALLEY/GREAT LAKES DURING THIS TIME.
STRONG WARM/MOIST ADVECTION WITHIN LLJ MAY BRING PRECIP TYPES
INTO QUESTION FOR THIS EVENT...ESPECIALLY SOUTHERN HALF. WITH SYSTEM
STILL 6 DAYS OUT WILL KEEP ANY SLEET/FREEZING RAIN (TRANSITIONAL
PTYPES) OUT OF THE FORECAST AND HOLD SHY OF LIKELY POPS GIVEN TIMING
DIFFERENCES AND POTENTIAL FOR FRONTAL WAVE TO BE MORE SUPPRESSED
THAN CURRENTLY MODELED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1248 AM EST TUE FEB 24 2015

NOT MUCH CHANGE WITH THE 06Z TAF PACKAGE. STILL EXPECT VFR
CONDITIONS TO PERSIST THROUGH LATE MORNING WITH INCREASING
SOUTHWESTERLY SURFACE WINDS AS GRADIENT TIGHTENS AHEAD OF NEXT
ARCTIC WAVE. THIS WAVE WILL SWING THROUGH MICHIGAN DURING THE
AFTERNOON AND GENERATE SOME LIGHT SNOW SHOWERS...MAINLY FOR KSBN.
NEW SNOW AMOUNTS WILL BE VERY LIGHT BUT STILL EXPECT A FAIR AMOUNT
OF BLOWING AND DRIFTING GIVEN STRONG WINDS AND DEEP PRE-EXISTING
SNOWPACK. CONTINUED WITH TEMPO IFR AT KSBN BUT DID PUSH PACK
TIMING OF WORST CONDITIONS SLIGHTLY. KFWA SHOULD REMAIN IN MVFR
CATEGORY WITH VERY LITTLE NEW SNOW. LOWER CIGS EXPECTED OVERNIGHT
IN CAA REGIME BUT HELD ABOVE FUEL ALTERNATE FOR NOW BASED ON
LATEST MOS GUIDANCE AND FORECAST SOUNDINGS.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR INZ008-009-
     016>018-023>027-032>034.

     WINTER WEATHER ADVISORY FROM 7 AM EST /6 AM CST/ THIS MORNING TO
     7 PM EST /6 PM CST/ THIS EVENING FOR INZ003>007.

MI...WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST THIS
     EVENING FOR MIZ077>081.

OH...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR OHZ002-004-
     005-015-016-024-025.

     WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST THIS
     EVENING FOR OHZ001.

LM...NONE.
&&

$$

UPDATE...MARSILI
SYNOPSIS...MCD
SHORT TERM...T
LONG TERM...STEINWEDEL
AVIATION...AGD


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