Area Forecast Discussion
Issued by NWS Northern Indiana

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FXUS63 KIWX 240602
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
102 AM EST MON NOV 24 2014

.SYNOPSIS...
ISSUED AT 621 PM EST SUN NOV 23 2014

A STRONG LOW PRESSURE SYSTEM WILL MOVE NORTHEAST ACROSS THE AREA
TONIGHT CAUSING WIDESPREAD RAIN. THE LOW WILL MOVE NORTHEAST INTO
CANADA ON MONDAY RESULTING IN VERY WINDY AND MUCH COLDER
CONDITIONS IN OUR AREA... WITH RAIN SHOWERS CHANGING TO SNOW SHOWERS IN
THE AFTERNOON. SOME LIGHT SNOW ACCUMULATIONS ARE POSSIBLE MONDAY
NIGHT AND TUESDAY MORNING...MAINLY ACROSS PORTIONS OF NORTHWEST
AND NORTH CENTRAL INDIANA...AND SOUTHERN LOWER MICHIGAN. LOWS
TONIGHT WILL BE IN UPPER 40S AND LOWER 50S... WITH TEMPERATURES
FALLING INTO THE 30S ON MONDAY.

&&

.UPDATE...
ISSUED AT 936 PM EST SUN NOV 23 2014

VERY STRONG LLJ ADVANCING NE ACROSS OH THIS EVE MIXING SOME
STRONGER WINDS TO THE SFC OVER ERN PORTIONS OF THE AREA WHICH
SHOULD CONT AT TIMES OVERNIGHT. CATEGORICAL POPS WORKING OUT WELL
BUT BUMPED UP QPF EARLIER WITH 1-2" RAINFALL TOTALS EXPECTED OVER
MOST OF THE AREA. LARGE AREA OF RAIN AHEAD OF LEAD NEG TILT SHRTWV
SHOULD LIFT NORTH OF THE CWA LATE TONIGHT... BUT SHOWERS WILL FILL
IN SHORTLY THEREAFTER...ESPECIALLY WRN PORTIONS AS FRONT AND
SECONDARY CHANNELED VORT MAX CLOSER TO MAIN UPR TROF APPROACH.
TSTMS HAVE BEEN OCRG THIS EVE OVER SRN MO IN AREA OF WK
INSTABILITY AND STEEP MID LEVEL LAPSE RATES. THESE FEATURES ARE FCST
TO LIFT NE ACROSS OUR CWA MONDAY MORNING AS CDFNT MOVES
THROUGH... SO HAVE ADDED A SLIGHT CHC OF TSTMS IN THAT TIMEFRAME.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 412 PM EST SUN NOV 23 2014

AN INTENSE UPPER LEVEL TROF AND ASSOCIATED UPPER LOW WILL LIFT NORTH
ACROSS THE AREA TONIGHT AND BECOME NEGATIVELY TILTED. THE LEFT EXIT
REGION OF A VERY STRONG UPPER LEVEL JET AND A 65 KT LOW LEVEL JET
WILL HELP AID IN THE DEVELOPMENT OF PRECIPITATION AS MOISTURE FLUX
INCREASES IN THE LOW LEVELS. RAISED RAINFALL AMOUNTS TO AROUND AN
INCH BY EARLY MONDAY. UPSTREAM PRESSURE FALLS HAVE DROPPED TO 8
MB/3HR... INDICATIVE OF A WELL/DEVELOPED SYSTEM WITH STRONG WARM AIR
ADVECTION IN THE LOWER LAYERS AND DIVERGENCE/DIFFLUENCE ALOFT. AS
FOR MONDAY...WINDY CONDITIONS ARE EXPECTED AS A VERY TIGHT SURFACE
GRADIENT MOVES OVER THE AREA. MUCH COLDER AIR WILL SPREAD ACROSS THE
AREA MONDAY BEHIND THE COLD FRONT WITH FALLING TEMPERATURES THROUGH
THE DAY. PRECIPITATION WILL CHANGE TO SNOW...ALTHOUGH NO SNOWFALL
ACCUMULATIONS ARE EXPECTED MONDAY.

&&

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 412 PM EST SUN NOV 23 2014

FEW CHANGES WRT LATEST LONG TERM PD. INTENSE SHORTWAVES WITHIN
LONGWAVE TROF FIRST LIFTING NWD FROM NERN MS WITH ADDNL ENERGY
ASSOCD UPSTREAM WITH EXIT REGION OF 140-150 KT ULVL JET TO EJECT
INTO OHIO VALLEY REGION IN NEG TILT FASHION WITH MARKED/RAPID
DEEPENING OF SFC REFLECTION LIFTING NNEWD FM ERN OK TO N OF LK SUPR
BY 18 UTC MON. CONTINUE TO FAVOR TIMING OF CHANGEOVER MONDAY NIGHT
WITH LAGGED WARM TW ALOFT TRAILING WELL BEHIND SFC FNTL ZONE
PASSAGE. HIEST POPS/QPF/SNOWFALL IN NWNR CWA IN LINE WITH STRONGEST
MID LVL DEFORMATION/DEEPER MSTR WRAPPING SFC LOW. FOLLOWED BY MODEST
LES RESPONSE WITH MID/UPPER TEENS LK/8H DIFFERENTIALS TONED DOWN BY
ANEMIC SATURATION WITHIN A SHALLOW DGZ LYR. NEXT NRN STREAM WAVE
EMITTED FM ALEUTIAN VORTEX FAVORS WEAK CLIPPER SYSTEM DROPPING SEWD
THROUGH NRN PLAINS TUE NIGHT INTO WRN GRTLKS WED AFNT/EVE. MODERATE
I285K ISENT UPGLIDE THOUGH WITH INITIAL MSTR SOURCE VOID MAY TAKE A
PROLONGED PD BEFORE TOP/DOWN SATURATION OCCURS WITH ASSOCD
FEATURE...WITH HIEST POPS WED NIGHT. THEREAFTER COASTAL CYCLOGENESIS
RAMPS LENDING TO WHITHER OF GRTLKS SYSTEM...PER MOST MODEL CONSENSUS
SANS GFSX. AGAIN ONLY A MODEST LES RESPONSE ANTICIPATED THU/THU
NIGHT AND PERHAPS AGAIN ABOUT SAT WITH LOW CONFIDENCE/WEAK
TRANSITORY SYSTEM PSBL.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1253 AM EST MON NOV 24 2014

IFR CIGS...WITH SOME TEMPORARY IMPROVEMENTS TO LOWER END MVFR ARE
EXPECTED FOR THE REMAINDER OF THE OVERNIGHT HOURS AS LOW LEVEL
WARM FRONT SURGES NORTHWARD ACROSS THE SOUTHERN GREAT LAKES
REGION. RAIN COVERAGE SHOULD TAPER OFF OVERNIGHT AS STRONGEST LEAD
THETAE ADVECTION FORCING AND INITIAL SHORTWAVE LIFT NORTHWARD.
BREAKS IN PRECIP WILL BE SHORT-LIVED HOWEVER AS LARGER SCALE UPPER
TROUGH DIGS ACROSS THE MID MS RIVER VALLEY. RELATIVELY UNSTABLE
CONDITIONS ALONG AND JUST BEHIND SFC FRONT MAY EVEN YIELD AN ISOLD
THUNDER THREAT BUT WILL HOLD OFF MENTION FOR TERMINAL FORECASTS
WITH EXPECTED VERY ISOLATED NATURE. BIGGER STORY WILL BE VERY
WINDY CONDITIONS THIS PERIOD...BEGINNING IN THE 14Z TIMEFRAME.
EVEN IN ADVANCE OF THE FRONT...INCREASED MIXING IN THE MORNING MAY
SUPPORT SOUTHWEST GUSTS AROUND 40 KNOTS AT KFWA...WITH STRONGER
WINDS AT KSBN PERHAPS MORE DELAYED UNTIL ACTUAL WIND SHIFT AROUND
15Z WHEN GUSTS TO 35 KNOTS WILL BE POSSIBLE. SCATTERED SNOW
SHOWERS ARE POSSIBLE MONDAY AFTERNOON INTO MONDAY EVENING...WITH
THE POTENTIAL OF A DUSTING OF ACCUMULATION AT KSBN. WINDS SHOULD
SLOWLY SUBSIDE MONDAY EVENING BUT WILL REMAIN GUSTY TO AROUND 30
KNOTS AT LEAST THROUGH EARLY EVENING.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WIND ADVISORY FROM 9 AM EST /8 AM CST/ THIS MORNING TO 7 PM EST
     /6 PM CST/ THIS EVENING FOR INZ003>009-012>018-020-022>027-
     032>034.

MI...WIND ADVISORY FROM 9 AM THIS MORNING TO 7 PM EST THIS EVENING
     FOR MIZ077>081.

OH...WIND ADVISORY FROM 9 AM THIS MORNING TO 7 PM EST THIS EVENING
     FOR OHZ001-002-004-005-015-016-024-025.

LM...GALE WARNING FROM 9 AM THIS MORNING TO 1 AM EST TUESDAY FOR
     LMZ043-046.

&&

$$

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


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