Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 240920
AFDIWX

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

.SYNOPSIS...
ISSUED AT 409 AM EST MON NOV 24 2014

A STRONG LOW PRESSURE SYSTEM TRACKING ACROSS THE GREAT LAKES
REGION TODAY WILL DRAG A STRONG COLD FRONT THROUGH THE REGION.
VERY WINDY CONDITIONS ARE EXPECTED TODAY AS THIS STORM SYSTEM
CONTINUES TO STRENGTHEN ACROSS THE GREAT LAKES. RAIN SHOWERS WILL
CHANGE TO SNOW SHOWERS AS COLDER AIR IS USHERED INTO THE
AREA...WITH A POTENTIAL OF SOME LIGHT SNOW ACCUMULATIONS ACROSS
PORTIONS OF NORTHWEST AND NORTH CENTRAL INDIANA...ALONG WITH
SOUTHERN LOWER MICHIGAN FROM TONIGHT INTO EARLY TUESDAY.
AFTER MORNING HIGHS IN UPPER 40S TO UPPER 50S...TEMPERATURES WILL
DROP SHARPLY THROUGH THE 40S AS THE COLD FRONT MOVES THROUGH. LOW
TEMPERATURES TONIGHT WILL DROP INTO THE MID TO UPPER 20S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 409 AM EST MON NOV 24 2014

MAIN FORECAST CONCERNS WILL CONTINUE TO CENTER ON VERY WINDY
CONDITIONS TODAY...CONVECTIVE POTENTIAL THIS MORNING...AND PRECIP
TYPE TRENDS THIS AFTERNOON ALONG WITH SOME LIGHT SNOW ACCUMULATIONS.

LEAD UPPER LEVEL SHORT WAVE IS BEGINNING TO LIFT NORTHWARD ACROSS
EXTREME NORTHERN INDIANA AND SOUTHERN LOWER MICHIGAN THIS
MORNING...WITH A LULL IN THE GREATER RAIN COVERAGE EXPECTED OVER THE
NEXT FEW HOURS. THIS LULL WILL BE SHORT LIVED AS ANOTHER VORT MAX
ACROSS SOUTHEAST MISSOURI SWINGS INTO THE OHIO VALLEY THIS MORNING.
ALREADY BEGINNING TO SEE A FEW REPORTS OF SUSTAINED WINDS IN THE 25
TO 35 MPH RANGE WITH A FEW GUSTS TO 40 TO 45 MPH ACROSS NORTHWEST
OHIO. THESE STRONGER GUSTS APPEAR TO BE CO-LOCATED WITH STRONG
ISALLOBARIC GRADIENT MARKING NORTHEAST DEPARTURE OF CORE OF STRONG
PRESSURE FALLS ACROSS SOUTHEAST ONTARIO. EXPECTING THESE WINDS TO
SUBSIDE A BIT OVER THE NEXT HOUR AS THE STRONGER ISALLOBARIC
GRADIENT SHIFTS NORTHEAST.

AN INCREASE IN SHOWERS IS EXPECTED AGAIN FROM THE SOUTHEAST IN
ASSOCIATION WITH THE SOUTHEAST MISSOURI VORT MAX. A BIT MORE
INSTABILITY IS EXPECTED WITH THIS VORT MAX AS WEAK MID LEVEL COLD
ADVECTION BEGINS TO IMPINGE ON LOW LEVEL THERMAL RIDGING ACROSS THE
AREA. 00Z NAM STILL DEPICT MUCAPES ON THE ORDER OF 100-300 J/KG
WORKING ACROSS THE AREA THIS MORNING BEFORE STRONG LOW LEVEL COLD
ADVECTION PUSH WITH THE FRONT. EXPECTING A SHARP INCREASE IN SFC
WIND SPEEDS ONCE AGAIN BY THE 12Z-15Z TIMEFRAME AS MAIN LOW LEVEL
THERMAL RIDGE SHIFTS ACROSS EXTREME NORTHEAST INDIANA/NORTHWEST
OHIO PROMOTING SOME BETTER MIXING. NAM/GFS/RAP BUFFER SOUNDINGS
ALL POINTING TO AT LEAST THE POTENTIAL OF MIXING DOWN SOME 50+ MPH
WIND GUSTS ACROSS FAR EASTERN PORTIONS OF THE AREA THIS
MORNING...PARTICULARLY ACROSS NORTHWEST OHIO COUNTIES. THIS THREAT
SHOULD MAXIMIZE IN THE 16Z-20Z TIMEFRAME WHEN STRONGER ISALLOBARIC
GRADIENT SHIFTS ACROSS THESE LOCATIONS. WITH POTENTIAL OF SHALLOW
CONVECTION ALSO WORKING ACROSS THE AREA THROUGH MIDDAY...WILL HAVE
TO WATCH FOR ANY ISOLATED HIGHER WIND GUSTS ASSOCIATED WITH
ENHANCED LOCALIZED MIXING OF STRONGER WINDS ALOFT. STILL
EXPECTING GUSTS INTO THE 40 TO 45 MPH RANGE ACROSS THE REMAINDER
OF THE AREA...PERHAPS A BIT MORE MARGINAL IN NATURE ACROSS THE
NORTHWEST. HAVE OPTED TO MAINTAIN GOING WIND ADVISORY...WITH A
MENTION OF 50+ MPH WIND GUSTS AS A POSSIBILITY ACROSS THE FAR
EAST THIS MORNING/EARLY AFTERNOON. A SLIGHT EXTENSION IN TIME FOR
THE WIND ADVISORY MAY BE NEEDED PAST 00Z ACROSS PORTIONS OF THE
AREA...BUT CONFIDENCE IS LOW AT THIS TIME.

IN TERMS OF PRECIP...BEST SYNOPTIC FORCING TO PERSIST ACROSS
NORTHWEST LOCATIONS TODAY AS NEXT VORT MAX DIGS ACROSS MID MS VALLEY
AND EVENTUALLY LIFTS NORTHEAST INTO THE WESTERN GREAT LAKES. BETTER
DEFORMATION FORCING BY THIS EVENING STILL APPEARS TO SET UP
NORTHWEST OF THE LOCAL AREA...ALTHOUGH COMBINATION OF LINGERING
SYNOPTIC FORCING AND WEAK LAKE ENHANCEMENT MAY SUPPORT MINOR
SNOW ACCUMULATIONS ACROSS PRIMARILY SOUTHWEST LOWER MICHIGAN
TONIGHT INTO TUESDAY. ONLY TWEAK TO WEATHER GRIDS THIS MORNING WAS
FOR JUST A SLIGHTLY SLOWER EVOLUTION TO SNOW SHOWER PTYPE THIS
AFTERNOON...BUT OTHERWISE NATURE OF PREVIOUS GRIDS REMAINS INTACT.
MORNING HIGHS MAY EVEN REACH 60 OR LOWER 60S ACROSS THE EXTREME
SOUTHEAST BEFORE SHARP LOW LEVEL COLD ADVECTION SETS IN LATER THIS
MORNING WITH TEMPERATURES FALLING THROUGH THE 40S ACROSS THE
AREA...AND INTO THE MID 30S ACROSS THE WEST.

&&

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 409 AM EST MON NOV 24 2014

AN UNWELCOMED RETURN TO COLD TEMP ANOMALIES THE PRIMARY WX STORY
MID-LATE WEEK AS ADDITIONAL EAST PACIFIC JET ENERGY HELPS REINFORCE
A RATHER DEEP EASTERN CONUS UPPER TROUGH. PIVOT THROUGH OF MID LVL
DEFORMATION AXIS/DEEPER SATURATION TUE AM AND ADDED MOISTURE FLUX
OFF LAKE MI WILL KEEP SNOW SHOWER/FLURRIES/CLOUDS AROUND TUESDAY
(MAINLY NORTH). MINOR ACCUMS POSSIBLE ALONG/NORTH OF THE TOLL ROAD
GIVEN LAKE-8H TEMP DIFFERENTIALS INTO THE UPPER TEENS/WESTERLY
FLOW...WITH LOW INVERSION HEIGHTS NEAR 5-6 KFT/SHALLOW DGZ LIMITING
FACTORS FOR MORE SUBSTANTIAL ACCUMS. THE NEXT CHANCE FOR LIGHT SNOW
WILL COME LATER WEDNESDAY-WEDNESDAY NIGHT AS CLIPPER SYSTEM DROPS SE
IN FLATTENING NW FLOW. LAST SEVERAL MODEL CYCLES HAVE TRENDED TOWARD
A MORE SOUTHERLY TRACK INTO THE MID MS/WESTERN OH VALLEYS PLACING
OUR SOUTHWESTERN ZONES IN A BETTER SPOT FOR A PERIOD OF LIGHT SNOW.
RENEWED SHOT OF MODIFIED POLAR AIR IN VEERED WNW FLOW IN WAKE OF
THIS WAVE SHOULD ALLOW LAKE EFFECT EFFECT SNOW SHOWERS/FLURRIES TO
DEVELOP ON THANKSGIVING. COULD SEE SOME ACCUMULATIONS/IMPACTS IN
FAVORED WNW FLOW ZONES AS 700 MB DELTA T`S PLUMMET INTO THE LOW-MID
20S AND INVERSION HEIGHTS INCREASE TO NEAR 10 KFT PER LATEST FCST
SOUNDINGS.

RELAXATION OF HEIGHT FIELD LATE IN THE WEEK/NEXT WEEKEND WITH POLAR
JET/LOW LEVEL BAROCLINIC ZONE POTENTIALLY LIFTING NORTH OF THE
FORECAST AREA SHOULD ALLOW MILDER/MORE SEASONABLE AIR TO BRIEFLY
ADVECT IN BY AROUND FRIDAY NIGHT-SATURDAY. A NARROW BAND OF LIGHT
SNOW MAY ACCOMPANY THIS WARM ADVECTION SURGE AROUND
FRIDAY...ALTHOUGH MODEL CONSENSUS SUGGEST MUCH BETTER CHANCES NORTH
OF THE FA. OTHERWISE....RAISED HIGHS CONSIDERABLY ON SATURDAY GIVEN
EXCELLENT 00Z MODEL AGREEMENT.

&&

.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 UNTIL 7 PM EST THIS EVENING FOR INZ007-009-018-026-
     027-033-034.

     WIND ADVISORY FROM 9 AM EST /8 AM CST/ THIS MORNING TO 7 PM EST
     /6 PM CST/ THIS EVENING FOR INZ003>006-008-012>017-020-
     022>025-032.

MI...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ081.

     WIND ADVISORY FROM 9 AM THIS MORNING TO 7 PM EST THIS EVENING
     FOR MIZ077>080.

OH...WIND ADVISORY UNTIL 7 PM EST THIS EVENING FOR OHZ001-002-004-005-
     015-016-024-025.

LM...GALE WARNING FROM 10 AM THIS MORNING TO 4 AM EST TUESDAY FOR
     LMZ043-046.

&&

$$

SYNOPSIS...MARSILI
SHORT TERM...MARSILI
LONG TERM...STEINWEDEL
AVIATION...MARSILI


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