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000
FXUS63 KIWX 081809
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
109 PM EST SUN DEC 8 2013

.SYNOPSIS...
ISSUED AT 1045 AM EST SUN DEC 8 2013

A DISTURBANCE WILL CONTINUE TO PROGRESS THROUGH THE REGION THIS
AFTERNOON...BRINGING A WINTRY MIX OF LIGHT SNOW AND FREEZING
FREEZING RAIN AND DRIZZLE THIS AFTERNOON AND TONIGHT. HIGHS TODAY
WILL BE IN THE UPPER 20S. LOWS TONIGHT WILL DIP IN THE MID 20S.
TEMPERATURES WILL REMAIN BELOW NORMAL FOR THE NEXT SEVERAL DAYS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 521 AM EST SUN DEC 8 2013

CHALLENGES TODAY AND TONIGHT INCLUDE MAINLY THE TYPE...EXTENT AND
DURATION OF PRECIPITATION. UPPER AIR SOUNDINGS CONTINUE TO SHOW DRY
LEVELS DEEP IN THE LOWER ATMOSPHERE. THE LATEST OVERNIGHT AIRCRAFT
SOUNDINGS SHOW THE LOWER LEVELS HAVE DRIED OUT AND CONTINUE TO SHOW
A DEEP DRY LAYER. AN UPPER LEVEL SYSTEM WILL LIFT NORTHEAST ACROSS
THE OHIO VALLEY WITH LIGHT PRECIPITATION EVENTUALLY EXTENDING NORTH
OF THE OHIO RIVER TO THE WESTERN GREAT LAKES REGION. FOR THIS
PACKAGE...FAVORED THE HI RES ARW EAST THAT APPEARS TO BE HANDLING
THIS EVENT WELL...ALTHOUGH SOME QUESTION OF HOW MUCH PRECIPITATION
WILL FALL GIVEN THE LARGE INITIALLY DRY LAYER. LOW LEVEL ISENTROPIC
LIFT SUPPORTS LIGHT SNOW OR FREEZING DRIZZLE/FREEZING RAIN FOR A
SHORT TIME. KEPT THE MENTION OF SNOW...WITH FREEZING DRIZZLE
POSSIBLE. BUFKIT SOUNDINGS SHOW LESS SUPPORT FOR SNOW OVER SOUTHEAST
AREAS...BUT FOR NOW KEPT A SNOW/FREEZING DRIZZLE MIX. PRECIPITATION
SHOULD BECOME ALL SNOW AND END EXCEPT FOR LAKE EFFECT SNOW BY LATE
TONIGHT.

&&

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 521 AM EST SUN DEC 8 2013

TRANSITION BACK TO COLDER TEMPERATURES TO START THE PERIOD AND
INCREASING LAKE EFFECT SNOW CHANCES WILL BE THE MAIN ITEMS OF
INTEREST FOR THE LONG TERM.

AN UPPER LEVEL VORT LOBE WILL ROTATE AROUND JAMES BAY POLAR LOW INTO
THE WESTERN GREAT LAKES ON MONDAY. THIS WILL ALLOW FOR STRONG LOW
LEVEL CAA ACROSS THE REGION ON MONDAY...WITH AFTERNOON HIGHS LIKELY
BEING REACHED IN THE MORNING. BULK OF THIS FORCING WILL BE TRACKING
NORTH OF THE AREA...BUT ASSOCIATED STRONG LOW LEVEL BAROCLINICITY
WITH THIS WAVE MAY BE ENOUGH TO GENERATE SOME SCATTERED LIGHT SNOW
SHOWERS OR FLURRIES ACROSS ESPECIALLY NORTHERN HALF OF THE AREA
MONDAY. OTHERWISE...CONCERN WILL SHIFT TO LAKE EFFECT SNOW SHOWER
POTENTIAL ACROSS SOUTHERN LOWER MICHIGAN BY MONDAY WITH A PRIMARILY
WESTERLY FETCH BECOMING ESTABLISHED. WEAKENING CAA WITH HEIGHT
SHOULD NOT RESULT IN OVERLY IMPRESSIVE DEPTHS TO LAKE INDUCED
INSTABILITY HOWEVER ON MONDAY...WITH DGZ ALSO POSSIBLY REMAINING
JUST ABOVE LOWER LIFT/BETTER LOW LEVEL RH. SYNOPTIC SCALE MID LEVEL
SUBSIDENCE ALSO TO INCREASE BY AFTERNOON IN WAKE OF AFOREMENTIONED
SHORT WAVE...SO GIVEN ABOVE FACTORS HAVE MAINTAINED JUST MID TO HIGH
CHANCE POPS MOST LOCATIONS FAR NORTHWEST...ALTHOUGH WITH WESTERLY
FETCH DID INCLUDE SOME LIKELY POPS ACROSS NORTHERN PORTIONS OF
BERRIEN COUNTY FOR LAKE EFFECT/LAKE ENHANCED SNOW SHOWERS.

FOR MONDAY NIGHT...MOISTURE DEPTH ALSO TO BE SOMEWHAT LIMITED FOR
SIGNIFICANT LAKE EFFECT SNOW SHOWERS WITH SYNOPTIC LOW LEVEL WINDS
LIKELY TO BACK LATE IN THE NIGHT IN ADVANCE OF NEXT FAST MOVING
CLIPPER TYPE SYSTEM/LOW LEVEL TROUGH. WATER VAPOR IMAGERY EARLY THIS
MORNING DOES SEEM TO SUGGEST RATHER COMPACT NATURE TO THIS VORT MAX
WHICH SHOULD LEND TO SOME SYNOPTIC CONTRIBUTION TO SNOW SHOWER
CHANCES ON TUESDAY. FOR TUESDAY MORNING DID TRY TO DEPICT A LULL IN
HIGHER CHANCE POPS DOWNWIND OF LAKE WITH MORE OF A SOUTHWEST LOW
LEVEL FLOW TRAJECTORY TAKING MAIN FOCUS FOR LAKE EFFECT SNOW SHOWERS
NORTH OF THE AREA...WITH INCREASING HIGH CHANCE POPS IN THE
AFTERNOON AS UPSTREAM VORT MAX APPROACHES AND WINDS VEER MORE
WESTERLY. MID LEVEL MOISTURE PROFILES ALSO LIKELY TO EXPERIENCE SOME
IMPROVEMENT BY THIS TIME GIVEN LARGER SCALE LIFT...AND THE
TUESDAY AFTERNOON-WEDNESDAY MORNING TIME PERIOD STILL APPEARS TO BE
ONE TO WATCH FOR ACCUMULATING LAKE EFFECT/LAKE ENHANCED SNOW
POTENTIAL. OTHERWISE...COLD CONDITIONS TO BLANKET THE REST OF THE
AREA WITH HIGHS LIKELY STRUGGLING INTO THE LOWER TO MID 20S FOR
TUESDAY/WEDNESDAY...AND WIND CHILLS HOVERING AROUND ZERO AT TIMES
DURING THIS PERIOD.

BY MIDWEEK...MEDIUM RANGE MODELS ARE STILL IN FAIRLY GOOD AGREEMENT
IN LOWER AMPLITUDE CLIPPER TYPE SYSTEM DROPPING INTO THE REGION WITH
PERHAPS SOME LOW END CHANCES FOR LIGHT SNOW SHOWERS/FLURRIES GIVEN
PREEXISTING STRONG BAROCLINIC ZONE. LAKE EFFECT SNOW SHOWER CHANCES
TO ALSO EXTEND INTO THE WEDNESDAY/WEDNESDAY NIGHT PERIOD...WITH SOME
VEERING OF LOW LEVEL WINDS TO WEST-NORTHWEST BEHIND THIS TROUGH
ALLOWING CHANCES TO EXTEND A BIT FURTHER SOUTH INTO FAR NORTHERN
INDIANA.

PREDICTABILITY BEGINS TO BREAKDOWN BY THE THURSDAY-SATURDAY
TIMEFRAME WITH MODELS EXHIBITING VASTLY DIFFERENT SCENARIOS IN
HANDLING HOW TO INGEST CUT OFF UPPER PV ANOMALY ACROSS SOUTHWEST
CONUS WHICH WILL HAVE IMPACTS ON TIMING ADDITIONAL SMALLER SCALE
NORTHERN STREAM WAVES. IT STILL DOES APPEAR THAT A TREND TO OVERALL
FLOW DEAMPLIFICATION AND RETREAT OF ARCTIC AIR MASS IS MORE LIKELY
BY THURSDAY/FRIDAY. WITH MEAN UPPER RIDGING EXPECTED TO BE
MAINTAINED ACROSS EASTERN PACIFIC/WESTERN CONUS AND INTERFACE OF
ARCTIC AIR MASS NOT EXPECTED TO BE TOO FAR NORTH OF THE AREA...LOCAL
AREA MAY REMAIN PRONE TO THIS BOUNDARY SINKING BACK SLIGHTLY
SOUTHWARD TOWARD THE FIRST PART OF THE WEEKEND. HOWEVER...LONGER
TERM MEDIUM RANGE MODEL CONSENSUS INTO LATE NEXT WEEKEND/EARLY
PORTIONS OF NEXT WEEK OFFER MORE AGGRESSIVE MODERATION IN TEMPS.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1256 PM EST SUN DEC 8 2013

EFFECTIVE ISENTROPIC LIFT PRODUCING SOME LIGHT SN ACRS NRN
IN...THOUGH MET CONDS TO HOLD UNTIL AT LEAST THIS EVENING.
THEREAFTER...TOP/DOWN SATURATION AND COLUMN COOLING AMID A WELL
PERTURBED 1-4KFT LYR TO LEAD TO LWRD CIGS IN WIDESPREAD STRATUS.
WITH TIME ICE NUCLEATION BECOMES AN INCREASED CONCERN AS CLOUD
TOPS WARM...ESPCLY INVOF KFWA AND LEADING TO LIGHT FZDZ QUITE
PSBL. COLDER PROFILE AT KSBN SHOULD AFFORD A BRIEF MIX OVERNIGHT.
BY DAYBREAK ANTICIPATE WIDESPREAD IFR-FUEL ALT CIGS ACRS
REGN...LOWEST AT KFWA IN CLOSER PROXIMITY TO MSTR TAP OVERNIGHT
AND LATER FROPA MON AM.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 4 AM MONDAY TO 4 AM EST TUESDAY FOR
     LMZ043-046.

&&

$$

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


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