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000
FXUS63 KIWX 101115
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
615 AM EST TUE DEC 10 2013

.SYNOPSIS...
ISSUED AT 203 AM EST TUE DEC 10 2013

A FAST MOVING CLIPPER SYSTEM WILL BRING A LOW CHANCE FOR SNOW
TODAY OVER MAINLY LOWER MICHIGAN. A SECOND SYSTEM WILL BRING A
BETTER CHANCE FOR ACCUMULATING SNOW LATE TONIGHT INTO WEDNESDAY.
HIGHS TODAY AND WEDNESDAY WILL BE IN THE LOW TO MID 20S. LOWS
TONIGHT WILL BE 10 TO 15.

&&

.SHORT TERM...(THIS AFTERNOON THROUGH WEDNESDAY)
ISSUED AT 611 AM EST TUE DEC 10 2013

ARCTIC AIR WAS SPREADING OVER THE FORECAST AREA EARLY THIS MORNING
WITH TEMPERATURES DROPPING TO NEAR ZERO OVER FAR NW INDIANA/VPZ.
CORRESPONDING WIND CHILL TEMPERATURES WERE APPROACHING 15
BELOW...AND SHOULD PERSIST EARLY THIS MORNING NEAR THESE VERY CHILLY
AIR TEMPERATURES WEST OF WARSAW. FOR NOW...HELD OF WITH A WIND CHILL
ADVISORY GIVEN THE LOW END OF A RELATIVELY BRIEF EVENT. LAKE EFFECT
SNOW DEVELOPMENT HAS BEEN VERY LIMITED GIVEN SHORT FETCH AND LOW
INVERSION HEIGHTS. THERE WILL BE A RELATIVELY SHORT DISRUPTION IN
LAKE EFFECT SNOW AS WINDS BACK TO THE SOUTHWEST AHEAD OF THE CLIPPER
SYSTEM. THE CURRENT CLIPPER TRACK MATCHES WELL WITH CLIMO
TRACKS...AND SHOULD BRING LITTLE MORE THAN A CHANCE FOR LAKE EFFECT
SNOW OVER FAR SW LOWER MICHIGAN THIS AFTERNOON. THE NEXT CLIPPER
TYPE OF SYSTEM WILL ALSO BRING A CHANCE FOR LIGHT SNOW LATE
TONIGHT...BUT AMOUNTS WILL BE LIGHT GIVEN LIMITED MOISTURE IN A DRY
AIRMASS. 280K ISENTROPIC SFC NOT SUPPORTIVE OF SNOW DEVELOPMENT WITH
LIMITED SATURATION. AS FOR TEMPERATURES...HIGHS TODAY MAY BE TOO
OPTIMISTIC IN THE MID 20S...ALTHOUGH WINDS SHOULD BACK MORE TO THE
SW THIS MORNING AND ALLOW TEMPERATURES TO RECOVER INTO THE 20S.

&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 611 AM EST TUE DEC 10 2013

LONG TERM PERIOD WILL BEGIN WITH SYNOPTIC SNOW POTENTIAL AS NEXT
UPPER PV ANOMALY CURRENTLY DIVING ACROSS SOUTHERN ALBERTA CANADA
PROGRESSES INTO THE SOUTHERN GREAT LAKES ON WEDNESDAY. UPPER
DYNAMICS NOT OVERLY IMPRESSIVE WITH HIGHLY SHEARED NATURE OF THIS
SHORT WAVE...BUT THIS WAVE WILL HAVE STRONG BAROCLINICITY TO WORK
WITH WHICH MAY ALLOW A NARROW ZONE OF BETTER LOW LEVEL MOISTURE
POOLING IN AN OTHERWISE VERY DRY ENVIRONMENT. MODEL OMEGA APPEARS TO
BE CLOSELY TIED TO STRONGER STRONGER 850-650 HPA FRONTOGENESIS
FORCING...WITH STRONGEST CONSENSUS FRONTOGENESIS RESPONSE ACROSS THE
NORTHWEST. WOULD SUSPECT THAT MODEL QPF FIELDS MAY BE TENDING TO
OVERDO AREAL EXTENT BUT WITH DIFFICULTIES AT THIS FORECAST DISTANCE
IN RESOLVING EXACTLY WHERE STRONGEST AXIS OF LOW/MID LEVEL
FRONTOGENESIS SETS UP. THUS...DID HAVE TO MAINTAIN A BROADBRUSH
NATURE TO 0.5 TO 1.5 INCH ACCUMULATIONS ACROSS APPROXIMATELY
NORTHERN HALF OF THE FORECAST AREA FOR WEDNESDAY. NAM/GFS
TIME/HEIGHT SECTIONS DO INDICATE A BIT OF A CROSSHAIR TYPE SIGNATURE
WITH STRONGER 850-700 HPA LIFT LINING UP WITH CORE OF DGZ.
HOWEVER...STABILITY ABOVE THIS FRONTAL FORCING DOES NOT APPEAR
HIGHLY SUPPORTIVE OF AN EFFICIENT RESPONSE. PREVIOUS FORECAST
ACCUMULATIONS GENERALLY KEPT AS IS WITH JUST SOME SLIGHT UPWARD
ADJUSTMENT ACROSS THE FAR NORTHWEST WHERE GREATER POTENTIAL MAY
EXIST FOR STRONGER FRONTAL FORCING AND ALSO WHERE SOME LAKE
CONTRIBUTION IS EXPECTED. APPROACH OF THIS WAVE ON WEDNESDAY WILL
LEAD TO BRIEF PERIOD OF DEEPER MID LEVEL MOISTURE PROFILES AND MORE
VEERED WEST NORTHWEST FLOW TOWARD MIDDAY. HOWEVER...MID LEVELS STILL
APPEAR TO DRY RAPIDLY BEHIND THE SYNOPTIC WAVE IN THE AFTERNOON.
GIVEN COMBINATION OF SYNOPTIC AND LAKE EFFECT/ENHANCED TYPE
EVENT...SOME CONCERN THAT PORTIONS OF FAR NORTHWEST ACROSS
BERRIEN/CASS MICHIGAN COUNTIES COULD GET A QUICK 2 OR 3 INCHES OF
SNOW WEDNESDAY. INCREASINGLY GUSTY WINDS BY LATE MORNING/AFTERNOON
IN WAKE OF SFC TROUGH PASSAGE COULD LEAD TO SOME HAZARDOUS TRAVEL
CONDITIONS ACROSS ESPECIALLY THESE LOCATIONS. WILL CONTINUE TO
HIGHLIGHT THIS POTENTIAL IN THE HWO THIS MORNING.

LOW LEVEL THERMAL TROUGH WILL BE ESTABLISHED ACROSS GREAT LAKES
REGION WEDNESDAY NIGHT...WITH BEST CHANCES OF SUBZERO READINGS
ACROSS THE SOUTHWEST AWAY FROM LAKE EFFECT STRATUS AND SLIGHTLY
WEAKER GRADIENT GIVEN SFC ANTICYCLONE POSITION ACROSS MID MS RIVER
VALLEY. HOWEVER EVEN FOR LAKE EFFECT AREAS...MAGNITUDE OF COLD WITH
THIS AIRMASS ALONG COULD PUSH READINGS INTO THE LOW SINGLE DIGITS
ABOVE ZERO. WIND CHILLS ARE STILL EXPECTED TO DROP INTO THE 0 TO 10
DEGREES BELOW ZERO RANGE FOR ALL OF THE FORECAST AREA WEDNESDAY
NIGHT. OF COURSE...FUTURE ADJUSTMENTS WILL NEED TO BE MADE DEPENDING
ON EXTENT OF NEW SNOWCOVER THAT EVOLVES ON WEDNESDAY. IN TERMS OF
PRECIP CHANCES...ADDITIONAL LAKE EFFECT ACCUMULATIONS SHOULD BE
MINOR GIVEN LOWERING INVERSION HEIGHTS OVERNIGHT AND DRY LOW/MID
LEVELS.

TEMPERATURE RECOVERY FOR THURSDAY STILL LOOKING MINIMAL. LOW LEVEL
WAA WILL BEGIN TO RAMP UP IN THE AFTERNOON...BUT THIS SHOULD ONLY
ACT TO REDUCE MIXING HEIGHTS AND WITH POTENTIAL NEW SNOWCOVER NO
CHANGES MADE TO PREVIOUS FORECASTED HIGHS IN MID TO UPPER TEENS.
SOME LINGERING LIGHT LAKE EFFECT SNOW SHOWERS OR FLURRIES ARE
POSSIBLE MAINLY FOR THE FIRST HALF OF THURSDAY ACROSS SOUTHERN LOWER
MICHIGAN BEFORE LOW LEVEL FLOW BACKS MORE SOUTHWESTERLY.

BY FRIDAY...ATTENTION WILL THEN SHIFT TO CUT OFF UPPER LOW OFF BAJA
OF CALIFORNIA COAST THAT WILL EVENTUALLY GET INJECTED BACK INTO
UPPER WESTERLIES. THE COMBINATION OF ADDITIONAL FAST MOVING NW FLOW
NORTHERN STREAM WAVES AND NORTHEAST EJECTION OF THIS TROUGH WILL
LIKELY SET UP A STRONG LOW/MID LEVEL THERMAL RIBBON ACROSS THE
REGION...AND MODELS HAVE CONTINUED TREND FROM 12Z GUIDANCE OF
DEPICTING SFC WAVE DEEPENING ACROSS OHIO VALLEY SATURDAY. GIVEN SOME
RUN TO RUN CONTINUITY IN THIS SCENARIO...GENERALLY BOUGHT IN ON
HIGHER CR ALLBLEND POPS ACROSS MOST OF FORECAST AREA FOR FRIDAY
NIGHT/SATURDAY WITH ACCUMULATING SNOW CONTINUING TO LOOK MORE
LIKELY. PASSAGE OF THIS TROUGH NOW APPEARS TO SET THE STAGE FOR
ANOTHER ARCTIC INTRUSION TOWARD THE END OF THE PERIOD...WHICH IS
ALREADY HANDLED WELL IN PREVIOUS FORECAST.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 611 AM EST TUE DEC 10 2013

THE EDGE OF A VERY COLD AIRMASS WAS OVER NRN INDIANA WITH A WEAK
UPPER LEVEL SYSTEM ACCOMPANIED BY LIGHT SNOW OVER EAST IA.
WINDS SHOULD BACK MORE TO THE SOUTHWEST AHEAD OF THIS ALBERTA CLIPPER
TYPE OF SYSTEM...WITH WINDS INCREASING TO OR ABOVE 20 KTS. A
SECOND SYSTEM SHOULD BRING A BETTER CHANCE FOR SNOW AND LOWER CIGS
LATE IN THE TAF PERIOD. CONDITIONS SHOULD REMAIN VFR EXCEPT FOR
SOME POSSIBLE LOWER CIGS AT SBN.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR LMZ043-046.

     GALE WARNING UNTIL 10 PM EST THIS EVENING FOR LMZ043-046.

&&

$$

SYNOPSIS...SKIPPER
SHORT TERM...SKIPPER
LONG TERM...MARSILI
AVIATION...SKIPPER


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