Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 191004
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
504 AM EST WED NOV 19 2014

.SYNOPSIS...
ISSUED AT 432 AM EST WED NOV 19 2014

AN UPPER LEVEL DISTURBANCE AND WARM FRONT WILL SPREAD LIGHT SNOW
INTO THE REGION THIS MORNING AND WILL TAPER OFF THIS AFTERNOON. A
COLD FRONT PASSING THROUGH THE REGION THIS AFTERNOON WILL LEAD TO
ANOTHER ROUND OF LAKE EFFECT SNOW SHOWERS FROM LATE THIS AFTERNOON
THROUGH THURSDAY EVENING WITH SIGNIFICANT SNOW ACCUMULATIONS
POSSIBLE ACROSS SOUTHWEST LOWER MICHIGAN AND PORTIONS OF EXTREME
NORTHWEST AND NORTH CENTRAL INDIANA. THE LAKE EFFECT SNOW SHOWERS
SHOULD GRADUALLY DIMINISH LATE THURSDAY NIGHT. HIGH TEMPERATURES
THIS AFTERNOON WILL RANGE FROM THE UPPER 20S TO LOWER 30S. LOW
TEMPERATURES TONIGHT WILL DROP INTO THE MID TO UPPER TEENS.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY AFTERNOON)
ISSUED AT 432 AM EST WED NOV 19 2014

SYNOPTIC SNOW THIS MORNING FOLLOWED BY ANOTHER LAKE EFFECT SNOW
SETUP WILL CONTINUE TO BE THE MAIN FORECAST CONCERN FOR THE SHORT
TERM. THE WINTER STORM WATCH WILL BE REPLACED WITH A WINTER STORM
WARNING FOR BERRIEN AND CASS COUNTIES IN SOUTHWEST LOWER
MICHIGAN...AND WITH A WINTER WEATHER ADVISORY ACROSS THE REMAINDER
OF THE WINTER STORM WATCH AREA.

WATER VAPOR IMAGERY EARLY THIS MORNING INDICATING NEXT UPSTREAM
SHORT WAVE DIGGING ACROSS SOUTHERN MINNESOTA/NORTHERN IOWA. AN AXIS
OF STRONG LOW LEVEL FLOW AND STRONG ISENTROPIC UPGLIDE WILL PRECEDE
THIS SHORT WAVE...ESPECIALLY CENTERED IN THE 09Z-18Z TIMEFRAME
TODAY. A BRIEF DURATION OF DEEPER RH WILL ACCOMPANY THE LOW/MID
LEVEL MOISTURE TONGUE IN ADVANCE OF THIS WAVE. NAM ISENTROPIC PROGS
STILL SUGGEST VERY STRONG NET OMEGA ON THE 285K SFC ACCOMPANYING
WARM ADVECTION FORCING THIS MORNING...WITH NORTHERN HALF OF FORECAST
AREA IN MORE FAVORED LOWER CONDENSATION PRESSURE DEFICIT REGION.
PROGRESSIVE NATURE OF THIS FORCING AND INITIALLY DRY PROFILES SHOULD
CUT DOWN ON SNOW AMOUNTS...WITH AROUND AN INCH OF ACCUMULATION
POSSIBLE FROM THIS MORNING TO EARLY AFTERNOON ACROSS NORTHERN HALF
...WITH ISOLATED SLIGHTLY HIGHER AMOUNTS POSSIBLE. DRY AIR
ADVECTION IN THE 850-750 HPA LAYER PARTICULARLY ACROSS SOUTHERN
HALF OF THE AREA COULD LEAD TO SOME LOW END PTYPE CONCERNS IN THE
FORM OF PATCHY LIGHT FREEZING DRIZZLE TOWARD LATTER PORTIONS OF
WARM ADVECTION FORCED PRECIP THIS AFTERNOON ACROSS NORTHEAST
INDIANA/NORTHWEST OHIO. AT THIS POINT...WILL OMIT FROM FORECAST
WITH LOW CONFIDENCE IN OCCURRENCE/IMPACT.

BY LATE THIS AFTERNOON INTO EARLY EVENING...LOW LEVEL COLD ADVECTION
WILL RAMP UP ONCE AGAIN LENDING TO RENEWED LAKE EFFECT SNOW SHOWER
CONCERNS. FETCH WILL REMAIN PRIMARILY WESTERLY TONIGHT WITH LAKE
INDUCED EQUILIBRIUM HEIGHTS INCREASING TO BETWEEN 12-14K FT LATE
EVENING INTO THE OVERNIGHT AS MID LEVEL THERMAL TROUGH SAGS INTO THE
GREAT LAKES REGION. LOWER HALF OF DGZ STILL APPEARS TO FALL INLINE
WITH CORE OF LOW LEVEL VERTICAL MOTIONS TONIGHT INTO
THURSDAY...ALTHOUGH INCREASING SYNOPTIC SCALE SUBSIDENCE LATER
WEDNESDAY NIGHT MAY TEND TO MAKE SATURATION IN CORE OF DGZ A BIT
MORE QUESTIONABLE. SOME VERY MINOR SYNOPTIC BACKING OF LOW LEVEL
WINDS COULD OCCUR THURSDAY MORNING IN ADVANCE OF NEXT UPPER LEVEL
WAVE DROPPING INTO THE WESTERN GREAT LAKES...BEFORE MORE OF
WEST-NORTHWEST FETCH IS ESTABLISHED ONCE AGAIN DURING THE AFTERNOON
HOURS. AS PREVIOUS DISCUSSION MENTIONED...FULL LAKE-700 HPA TEMP
DIFFERENTIALS MAY BE DIFFICULT TO REALIZE GIVEN DRY PROFILES ABOVE
THE INVERSION...WITH ANOTHER LIMITING FACTOR BEING INVERSION
HEIGHTS/AND LAKE INDUCED EQUILIBRIUM LEVELS NOT QUITE AS PRONOUNCED
AS PREVIOUS EVENT. HOWEVER...WITH LONG DURATION SETUP...AND BOUTS OF
SOME SYNOPTIC ENHANCEMENT...COULD SEE SOME MULTI-PERIOD TOTAL SNOW
ACCUMULATIONS FROM WEDNESDAY EVENING THROUGH EARLY THURSDAY EVENING
IN EXCESS OF 6 INCHES ACROSS SOUTHWEST LOWER MICHIGAN. PRIMARILY
WESTERLY FETCH THROUGH MOST OF THE EVENT LENDS TO SOME LOWER
CONFIDENCE IN TOTAL ACCUMULATIONS FOR FAR NORTHWEST/NORTH CENTRAL
INDIANA...BUT MUCH LIKE THE PREVIOUS EVENT...HIGHER END ADVISORY
AMOUNTS ARE A POSSIBILITY NORTH OF THE TOLL ROAD. GREATEST SNOW
ACCUMULATIONS OF 4 TO 8 INCHES WITH LOCALLY HIGHER AMOUNTS ARE
EXPECTED ACROSS BERRIEN/CASS COUNTY WITH SOME POSSIBILITY THAT
HIGHEST TOTALS MAY BE SHIFTED INLAND A BIT GIVEN STRONG BACKGROUND
FLOW.

HAVE REPLACED THE WINTER STORM WATCH WITH A WINTER STORM WARNING FOR
BERRIEN/CASS COUNTIES IN SW LOWER MICHIGAN. ELSEWHERE...HAVE REPLACED
THE WINTER STORM WATCH WITH A WINTER WEATHER ADVISORY FOR STORM
TOTAL ACCUMULATIONS IN THE 2 TO 6 INCH RANGE...WITH THE HIGHER END
OF THIS RANGE A STRONGER POSSIBILITY CLOSER TO THE
INDIANA/MICHIGAN STATELINE...AND ACROSS ST.JOSEPH MICHIGAN COUNTY.
WEST WINDS OF 15 TO 25 MPH WITH A FEW GUSTS TO 30 MPH WILL LIKELY
CREATE SIGNIFICANT BLOWING AND DRIFTING CONCERNS ONCE AGAIN
TONIGHT AND THURSDAY WITH SIGNIFICANTLY REDUCED VISIBILITIES AT TIMES.
NO CHANGE MADE TO THE TIMING OF THE HEADLINES...ALTHOUGH LAKE
INDUCED EQUILIBRIUM HEIGHTS SHOULD BEGIN TO LOWER BY THURSDAY
EVENING. STILL SOME LOWER CONFIDENCE EXISTS IN REGARDS TO ONSET OF
RENEWED LAKE EFFECT SNOW SHOWERS...WITH POTENTIAL OF HEAVIER SNOW
SHOWERS AFTER 00Z THIS EVENING. AT THIS TIME HOWEVER...WILL MAKE
NO CHANGES TO PREVIOUS HEADLINES GIVEN INCREASED WINDS LATER THIS
AFTERNOON POTENTIALLY LEADING TO BLOWING AND DRIFTING CONCERNS
ONCE AGAIN.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 502 AM EST WED NOV 19 2014

LAKE EFFECT SNOW SHOWERS WILL BE WEAKENING THURSDAY NIGHT AS DEEP
SUBSIDENCE INCREASES WITH FALLING INVERSION HEIGHTS. EXPECT
ANOTHER 1 TO 2 INCHES OF SNOW OVER FAR SOUTHWEST LOWER MICHIGAN.
ONE LAST VERY COLD DAY FRIDAY WHICH WILL CONCLUDE ONE OF THE
COLDEST 7 DAY STRETCHES IN NOVEMBER IN THE AREA DURING THE PAST
100 YEARS. HIGHS FRIDAY WILL BE CLOSE TO 25 DEGREES BELOW NORMAL.
WARM AIR ADVECTION WILL INCREASE FRIDAY NIGHT AND SATURDAY. MADE
SOME CHANGES TO TEMPS AND WEATHER GIVEN THE THERMAL PROFILES. A
WARM LAYER OVER 5C WILL OVERSPREAD THE VERY COLD AIRMASS DURING
THIS TIME...WITH SNOW CHANCES ENDING. THE PRECIPITATION WILL BE
EITHER SLEET OR FREEZING RAIN DEPENDING ON THE DEPTH OF THE COLD
LAYER. THE COLD LAYER SHOULD MIX OUT ENOUGH BY EARLY SATURDAY
AFTERNOON...ALLOWING SURFACE TEMPERATURES TO RISE ABOVE FREEZING
WITH THE PRECIPITATION BECOMING ALL RAIN. RAIN IS POSSIBLE
SATURDAY AFTERNOON THROUGH MONDAY WITH AMOUNTS AROUND A HALF TO
THREE/QUARTERS OF AN INCH.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)
ISSUED AT 1245 AM EST WED NOV 19 2014

STRONG LOW LEVEL WARM ADVECTION SHOULD ALLOW LIGHT SNOW TO DEVELOP
TOWARD DAYBREAK AFFECTING THE TERMINALS GENERALLY IN THE 12Z-18Z
TIMEFRAME WITH PERIODS OF IFR VSBYS EXPECTED. SOME LIGHT
ACCUMULATIONS OF AN INCH OR LESS ARE EXPECTED BEFORE SNOW
DIMINISHES THIS AFTERNOON. STRONGEST ISENTROPIC ASCENT WILL SHIFT
NORTHEAST/EAST OF THE AREA EARLY THIS AFTERNOON BUT SOME LIGHT
SNOW OR FLURRIES MAY PERSIST ACROSS NORTHEAST INDIANA AS WEAK
MID/UPPER LEVEL TROUGH PASSES THROUGH THE AREA. ALONG WITH LOW
LEVEL MOISTURE ADVECTION/PRECIP LATER THIS MORNING...HAVE
CONTINUED TREND TO MVFR CIGS AFTER 12Z. MARGINAL LLWS CRITERIA MAY
ALSO BE MET EARLY WEDNESDAY MORNING...PARTICULARLY ACROSS
NORTHEAST INDIANA WHERE STRONGEST LOW LEVEL SOUTHERLY FLOW IS
EXPECTED.

RENEWED LOW LEVEL COLD ADVECTION TONIGHT BEHIND THIS SYSTEM WILL
SET UP REDEVELOPMENT OF LAKE EFFECT SNOW SHOWERS...AND WITH
WESTERLY FETCH...HEAVIEST SNOW SHOWERS ARE EXPECTED ACROSS
SOUTHERN LOWER MICHIGAN. HOWEVER...BURSTS OF IFR CONDITIONS ARE
ANTICIPATED AT KSBN WEDNESDAY NIGHT. GUSTY SOUTHWEST WINDS TO
DEVELOP WEDNESDAY MORNING IN ASSOCIATION WITH WARM FRONT...WITH
STRONG GRADIENT AND LOW LEVEL COLD ADVECTION MAINTAINING 25 TO 30
KNOT GUSTS THIS AFTERNOON.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY FROM 4 PM EST /3 PM CST/ THIS AFTERNOON
     TO 4 AM EST /3 AM CST/ FRIDAY FOR INZ003>006.

MI...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EST
     FRIDAY FOR MIZ079-080.

     WINTER STORM WARNING FROM 4 PM THIS AFTERNOON TO 4 AM EST FRIDAY
     FOR MIZ077-078.

OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 AM EST FRIDAY FOR LMZ043-046.

&&

$$

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


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