Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 282016
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
316 PM EST SUN DEC 28 2014

.SYNOPSIS...
ISSUED AT 1248 PM EST SUN DEC 28 2014

CANADIAN HIGH PRESSURE WILL BRING COOL AND DRY CONDITIONS TO THE
AREA TODAY WITH GRADUAL CLEARING THIS AFTERNOON. HIGH
TEMPERATURES WILL REMAIN IN THE MID 30S WITH LOWS TONIGHT IN THE
LOW TO MID 20S. THERE IS A CHANCE OF LAKE EFFECT SNOW MONDAY
INTO TUESDAY AS MUCH COLDER AIR FILTERS INTO THE REGION.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 312 PM EST SUN DEC 28 2014

DRIER AIR WAS CONTINUING TO SPREAD INTO NORTHERN INDIANA UNDER A
HIGH CLOUD CANOPY WITH THE LOWER CLOUDS RETREATING SOUTHEAST.
ANOTHER COLD FRONT WILL MOVE SOUTH TONIGHT WITH WINDS BECOMING NORTH
AND NORTHEAST BEHIND THE FRONT. DELTA T VALUES WILL CLIMB TO AROUND
15C BY THE MIDDLE OF THE DAY...HOWEVER THE FETCH WILL BE UNFAVORABLE
FOR LAKE EFFECT SNOW OVER FAR SW LOWER MICHIGAN INTO NORTHERN
INDIANA WITH WINDS BECOMING NORTH/NORTHEAST BY MID DAY MONDAY.
ALSO...LOW LEVEL SHEAR IN THE CLOUD LAYER IS SIGNIFICANT...AND
SHOULD GREATLY LIMIT ANY SNOW SHOWERS.

&&

.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 312 PM EST SUN DEC 28 2014


THE EARLY PART OF THE LONG TERM PERIOD FOCUSES ON LAKE EFFECT SNOW
CHANCES MONDAY NIGHT THROUGH TUESDAY NIGHT...FOLLOWED BY MUCH COLDER
TEMPERATURES FOR THE MIDDLE PART OF THE WEEK. A STRONGER SYSTEM WILL
IMPACT THE AREA NEXT WEEKEND...BRINGING THE NEXT CHANCE FOR
WIDESPREAD PRECIPITATION TO THE FORECAST AREA.

STRONG PACIFIC UPPER JET WILL BUCKLE THE UPPER FLOW PATTERN ACROSS
THE EASTERN PACIFIC/WESTERN CONUS EARLY THIS WEEK. A SERIES OF WEAK
WAVES WILL EJECT FROM THIS WESTERN CONUS TROF THROUGH THE
QUASI-ZONAL EASTERN CONUS FLOW...WITH A 125-150KT UPPER JET
EXTENDING FROM THE CENTRAL CONUS EASTWARD INTO THE NORTHERN PACIFIC.
A STRONG ARCTIC SFC HIGH WILL ADVECT DOWN THE LEE OF THE ROCKIES
INTO THE CENTRAL CONUS...WHICH WILL BRING NORTHERLY FLOW/CAA TO THE
GREAT LAKES/MIDWEST. THIS WILL SET THE STAGE FOR LAKE EFFECT SNOW
CHANCES BEGINNING MONDAY NIGHT.

LOW LEVEL FLOW WILL BE MORE CONDUCIVE FOR SNOWFALL JUST WEST OF THE
FORECAST AREA INITIALLY MONDAY NIGHT. AS THE FLOW GRADUALLY BACKS
THROUGH THE OVERNIGHT AND TUESDAY...POPS INCREASE ACROSS THE
NORTHWEST PART OF THE CWA. HELD WITH THE SAME GENERAL TREND FOR POPS
DURING THIS TIMEFRAME. FLOW CONTINUES TO BACK WESTERLY TUESDAY NIGHT
INTO WEDNESDAY...WHICH WILL CONFINE SNOW CHANCES TO SOUTHWEST LOWER
MICHIGAN. AMOUNTS FROM MONDAY NIGHT THROUGH WEDNESDAY ARE EXPECTED
TO BE FAIRLY LIGHT IF ANYTHING...WITH MOST SPOTS SEEING LESS THAN AN
INCH OF SNOW. SOME AREAS CLOSER TO THE LAKE IN NORTHERN LAPORTE AND
SOUTHWEST BERRIEN COUNTIES COULD SEE A TOTAL OF ONE TO TWO INCHES
THROUGH THIS TIMEFRAME.

TEMPERATURES WILL BE COLDER THROUGH THIS PERIOD...ALTHOUGH WEDNESDAY
CONTINUES TO LOOK LIKE THE COLDEST DAY OF THE WEEK. DROPPED HIGH
TEMPERATURES A DEGREE OR TWO WEDNESDAY...AS SOME AREAS MAY REMAIN IN
THE TEENS DURING THE DAYTIME.

FORECAST STILL REMAINS QUESTIONABLE BEYOND THURSDAY. MID-RANGE
GUIDANCE SOLUTIONS STILL EXHIBITING A FAIR AMOUNT OF RUN TO RUN
INTER/INTRA MODEL INCONSISTENCY. MAIN FOCUS IS CUTOFF LOW OVER THE
FOUR CORNERS REGION LATE IN THE WEEK. AS THIS SYSTEM EJECTS
NORTHEAST TOWARD THE REGION AND PHASES WITH THE NORTHERN
STREAM...PRECIP CHANCES LOOK TO INCREASE TOWARD SATURDAY. 12Z GFS
NOT TO DISSIMILAR FROM THE PREVIOUS RUN...WHICH EJECTS THIS WAVE
INTO THE SOUTHERN PLAINS BY SATURDAY MORNING. AS THE FEATURE BECOMES
POSITIVELY TILTED...A BROAD AREA OF ASCENT MAY OVERSPREAD PRECIP
ACROSS THE REGION LATE FRIDAY INTO SATURDAY. THE WAVE THEN EJECTS
NORTHEAST THROUGH THE REGION WITH A DEEPENING SURFACE RESPONSE.
HOWEVER...THE 12Z ECMWF IS MUCH SLOWER WITH EJECTING THIS WAVE. THIS
SUPPRESSED SOLUTION KEEPS THE WAVE CLOSED AND NEGATIVELY/NEUTRALLY
TITLED THROUGH THE SOUTHERN PLAINS SATURDAY AFTERNOON/NIGHT INTO THE
TENNESSEE/OHIO VALLEY ON SUNDAY. THIS SOLUTION WOULD REALLY LIMIT
PRECIP CHANCES ACROSS THE REGION DURING THIS PERIOD.

NOT ONLY DOES THE INCONSISTENCY BETWEEN THE TRACK/EVOLUTION OF THE
SYNOPTIC PATTERN THROW A WRENCH IN THE FORECAST...THERMODYNAMIC
PROFILES AHEAD AND DURING THE SYSTEM MAY BRING P-TYPE ISSUES INTO
THE FOLD. WITH THE BROAD ASCENT AHEAD OF THE SYSTEM IN THE GFS
SOLUTION...STRONG WAA SUGGESTS A PERIOD OF FREEZING RAIN EARLY
SATURDAY MORNING. A MORE SUPPRESSED ECMWF LIMITS THE AMOUNT OF WAA
INTO THE REGION...WITH A MAINLY FROZEN P-TYPE EXPECTED WITH ANY
PRECIPITATION. WITH THE VOLATILE MODEL SOLUTIONS THIS FAR OUT AND
LOW CONFIDENCE...MADE NO MAJOR CHANGES TO POPS AND/OR WEATHER TYPE
DURING THIS TIME FRAME.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1224 PM EST SUN DEC 28 2014

DRIER AIR WAS CONTINUING TO SPREAD INTO NORTHERN INDIANA UNDER A
HIGH CLOUD CANOPY AND WITH THE MVFR SC DECK RETREATING SOUTHEAST.
SOME UPSTREAM MOISTURE OFF LAKE MICH WAS CAUSING CLOUDS TO FORM
OVER MUCH OF THE LENGTH OF THE EASTERN SHORE OF LAKE MICH.
HOWEVER...A SFC RIDGE AXIS JUST UPSTREAM SHOULD HELP KEEP FLOW
SOUTHWEST TO WEST OVER THE EXTREME SOUTHERN SHORE OF LAKE MICH
AND HELP PREVENT ADDITIONAL MVFR LAKE CLOUDS FROM MOVING INTO
THE SBN TERMINAL. THEREFORE...WENT WITH AN 1830Z CLEARING AT
SBN...AND A LITTLE LATER AT FWA. SO CONDITIONS SHOULD BECOME VFR
WITH WINDS BECOMING LIGHT TONIGHT.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&

$$

SYNOPSIS...AGD/SKIPPER
SHORT TERM...SKIPPER
LONG TERM...NG
AVIATION...SKIPPER


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