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000
FXUS63 KIWX 130515
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
115 AM EDT THU MAR 13 2014

.SYNOPSIS...
ISSUED AT 402 PM EDT WED MAR 12 2014

A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION LATE TONIGHT
INTO THURSDAY MORNING RESULTING IN DECREASING CLOUDS...DIMINISHING
WINDS...AND VERY COLD CONDITIONS. THIS HIGH WILL SHIFT TO THE EAST
THURSDAY WHICH WILL ALLOW SOUTH WINDS TO BRING MODERATING
CONDITIONS FOR THURSDAY AND FRIDAY.

&&

.UPDATE...
ISSUED AT 852 PM EDT WED MAR 12 2014

A FEW MINOR TWEAKS MADE TO THE FORECAST THIS EVENING MAINLY TO
ACCOUNT FOR CURRENT SKY COVER TRENDS. A COUPLE OF AREAS OF
STRATOCU PERSIST EARLY THIS EVENING...THE FIRST AREA DOWNWIND OF
LAKE MICHIGAN...AND A SECOND AREA ACROSS FAR NORTHEAST
INDIANA/NORTHWEST OHIO IN VICINITY OF INVERTED SFC TROUGH. INFLUX
OF VERY DRY LOW LEVEL AIR AND EASTWARD PROGRESSION OF UPPER TROUGH
AXIS WILL ALLOW FOR EROSION OF LOW CLOUDS LATE THIS EVENING AND
ENDING OF ANY REMAINING FLURRIES. APPROACH OF LOW LEVEL RIDGE
AXIS WILL RESULT IN DIMINISHING WINDS AND BETTER RADIATIONAL
COOLING CONDITIONS. PREVIOUS MINS ZERO TO 5 BELOW FAR NORTHEAST TO
ZERO TO FIVE ABOVE FAR WEST STILL APPEAR REASONABLE BASED ON
EVOLUTION OF LOW LEVEL THERMAL TROUGHING WITH MAIN FORECAST
UNCERTAINTIES RESTING WITH EXTENT OF DECOUPLING IN THE EAST. WIND
CHILLS MAY NUDGE UP AGAINST ADVISORY CRITERIA FOR A SHORT TIME
ACROSS THE EAST EARLY THURSDAY...BUT WILL NOT ISSUE ANY HEADLINES
AT THIS TIME.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 402 PM EDT WED MAR 12 2014

SNOWFALL EXITING RAPIDLY THIS AFTERNOON WITH A WELL DEVELOPED
DEFORMATION/FGEN AXIS ORIENTED NEARLY ORTHOGONAL TO THE SYSTEM
MOTION VECTOR. A FEW FLURRIES WILL BE POSSIBLE IN OUR EASTERN
COUNTIES THROUGH THE EARLY EVENING GIVEN LINGERING MOISTURE AND WEAK
HIGH-BASED FORCING BUT A SHARP INCREASE IN SUBSIDENCE EXPECTED BY
03Z AS MIDLEVEL TROUGH AXIS EXITS THE CWA. LITTLE TO NO ADDITIONAL
ACCUMULATION IS EXPECTED AND REMAINING HEADLINES WILL BE DROPPED
WITH THE AFTERNOON PACKAGE. MAIN FORECAST CONCERN FOR THE SHORT TERM
WILL BE OVERNIGHT LOWS. COLD AIRMASS NOTED ON 12Z GRB SOUNDING WILL
FILTER OVER THE SOUTHERN GREAT LAKES TONIGHT. NEARLY IDEAL RADIATIVE
CONDITIONS WILL DEVELOP BY LATER TONIGHT AS STRONG SUBSIDENCE LEADS
TO CLEAR SKIES AND A SURFACE RIDGE AXIS DIRECTLY OVERHEAD. WITH A
FRESH...ALBEIT RATHER WET...SNOWPACK IN PLACE...EXPECT TEMPS TO DROP
PRECIPITOUSLY OVERNIGHT. STAYED GENERALLY CLOSE TO INHERITED
FORECAST AND CONSENSUS BLENDS WITH VALUES AROUND ZERO FOR MOST
LOCATIONS. THIS WILL BE NEAR THE RECORD LOW OF 1 FOR BOTH SBN (SET
IN 1896) AND FWA (SET IN 1948). WIND CHILL VALUES MAY BE FLIRTING
WITH ADVISORY CRITERIA OF -15F IN A FEW AREAS BUT EXPECT WINDS WILL
DROP IF/WHEN RAW TEMPS GET COLD ENOUGH AND WILL FORGO ANY HEADLINE
ISSUANCE. TEMPS SHOULD REBOUND NICELY BY LATE TOMORROW AFTERNOON AS
MIDLEVEL HEIGHTS QUICKLY CLIMB AND WSW LOW LEVEL FLOW DEVELOPS.
WILL PROBABLY BE SOME INCREASING MID/UPPER LEVEL CLOUDS WITH
ASSOCIATED WAA BUT EXPECT AT LEAST PARTLY SUNNY CONDITIONS FOR MUCH
OF TOMORROW. HIGHS SHOULD EASILY REACH THE LOW TO MID 30S IN THE
SOUTHWEST WITH MID 20S IN THE NORTHEAST. NO PRECIP EXPECTED AS WARM
FRONT PASSES WELL TO OUR NORTH.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 402 PM EDT WED MAR 12 2014

SHRTWV TOPPING WEST COAST RIDGE TODAY WILL TRACK SE TO THE NRN
PLAINS THU NGT AND THEN EAST ACROSS THE UPR GRTLKS FRIDAY. WARM
AIRMASS WILL OVERSPREAD OUR AREA AHEAD THIS SYSTEM BUT SFC WARMUP
SHOULD BE TEMPERED SOMEWHAT BY SNOWCOVER IN OUR AREA...FCST SLOWLY
RISING TEMPS THU NGT WITH HIGHS FRIDAY RANGING FROM THE L40S NORTH
TO THE L50S SOUTH. ALTHOUGH THIS AIRMASS WILL BE QUITE DRY...
SUFFICIENT LOW LEVEL CONVERGENCE AND MOISTURE ADVECTION MAY OCCUR
ALONG/AHEAD CDFNT MOVG THROUGH THE AREA FRI EVE FOR SOME SHOWERS
OVER ERN PORTIONS OF THE CWA. BEHIND THIS CDFNT... HIGH PRESSURE OF
ARCTIC ORIGIN WILL MOVE SE INTO THE GRTLKS BY SUNDAY RESULTING IN
DRY WX AND BLO NORMAL TEMPS OVER THE WEEKEND AND INTO EARLY NEXT
WEEK.

NEXT SHRTWV TO TOP WRN RIDGE AND AFFECT OUR AREA SHOULD COME IN THE
TUE-WED TIMEFRAME. LARGE TIMING/STRENGTH DIFFERENCES REMAIN AMONG
MEDIUM RANGE MODELS WRT THIS SYSTEM. ATTM FCST TEMPS NEAR NORMAL
WITH LOW PRECIP CHANCES BUT SGFNT ADJUSTMENTS ARE PSBL IN THE NEXT
FEW DAYS AS WIDELY DISPARATE MODEL SOLUTIONS HOPEFULLY COME INTO
BETTER AGREEMENT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 113 AM EDT THU MAR 13 2014

VFR MET CONDS THROUGH THE FCST PD WITH DRY/SUBSIDENT AIRMASS IN
PLACE. HIGH BELTED CLIPPER SYSTEM TO TRACK ESEWD TOWARD MN
ARROWHEAD BY LATE IN FCST PD. LEADING SWRLY FLOW RAMPS TO AROUND
50KTS PROVIDING DIRECTIONAL/SPEED SHEAR CONCERNS ACRS NRN IN.

&&

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

$$

UPDATE...MARSILI
SYNOPSIS...MARSILI
SHORT TERM...AGD
LONG TERM...JT
AVIATION...MURPHY


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