Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 080933
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
433 AM EST MON FEB 8 2016

.SYNOPSIS...
ISSUED AT 424 AM EST MON FEB 8 2016

ACCUMULATING SNOWFALL IS EXPECTED ACROSS MUCH OF THE GREAT LAKES
THROUGH AT LEAST THURSDAY. AMOUNTS DURING ANY ONE PERIOD WILL BE
GENERALLY LIGHT...BUT THE LONG DURATION OF THE EVENT MAY ALLOW
AREAS NEAR LAKE MICHIGAN TO SEE BETWEEN 6 AND 12 INCHES OF SNOW
BY THE TIME THURSDAY MORNING ARRIVES. A BLAST OF ARTIC AIR IS
POISED TO IMPACT THE REGION BY THE WEEKEND WITH AFTERNOON HIGHS
STRUGGLING THROUGH THE TEENS AND LOWS IN THE SINGLE DIGITS.

&&

.SHORT TERM...(TODAY THROUGH WEDNESDAY NIGHT)
ISSUED AT 424 AM EST MON FEB 8 2016

PRIMARY FOCUS FROM NEAR TERM THROUGH WED NIGHT IS TO DELAY ONSET OF
PRIMARY LES EVENT OWING TO SLOW SWRN GRTLKS FUJIWHARA WITH CONSERTED
COLD POOL PLUNGE DLAD. INITIAL SHEARED ENVIRONMENT AND MODEST
DIFFERENTIALS TO PROVIDE SOME LAKE ENHANCEMENT OF SYNOPTIC
MOISTURE/ARCTIC FRONTAL SHSN WITH EPISODIC WAVES OF ENHANCED
DEFORMATION/DCVA EMMINATING FROM THE UPPER MS VLY REGION. UNTIL 180
KT ULVL JET PRESENTLY TOPPING RIDGE/FAR NRN BC DRIVES SWD TOWARDS
LWR MO VALLEY ON TUE WILL LES INGREDIENTS TO CONGEAL. LAKE EFFECT
CAPE AND LAKE INDUCED EQL APPEAR BROADLY RAMPED WITH RESPECT TO TIME
AND PEAK ON ORDER OF 400 J/KG AND 13 KFT WED AFT RESPECTIVELY.
ANTICIPATE A FEW LES BANDS TO BECOME WELL ESTABLISHED AND PERSIST
TUE NIGHT INTO WED...IF NOT INTO FIRST HALF WED NIGHT BEFORE
DOWNTURN STARTS. TOTAL ACCUMS ESTABLISH WELL WITHIN RANGE OF
MULTIMODEL COBB AVERAGES WITH/WITHOUT COMPACTION AND CLOSE TO OR
SLIGHTEST UPWARD NUDGE OVER PRIOR FORECASTS AND CONSISTENT WITH
TRENDS.

&&

.LONG TERM...(THURSDAY THROUGH SUNDAY)
ISSUED AT 424 AM EST MON FEB 8 2016

DEEP UPPER LEVEL TROUGH WILL BEGIN TO FINALLY PULL AWAY FROM THE
AREA. NW FLOW WILL PERSIST THROUGH AT LEAST THE FIRST HALF OF
THURSDAY WITH HIGH CHC TO LIKELY POPS WARRANTED FOR LIGHT QPF/ACCUMS
AS DELTA T`S IN THE MID 20S. ALIGNMENT OF DGZ AND BEST LIFT WILL NOT
BE FULLY MESHED BUT STILL ENOUGH TO HOLD ONTO HIGHER POPS THAN
DEPICTED BY SUPERBLEND OF MODELS.

LOW LEVEL FLOW AND THERMAL CONTRIBUTIONS WILL BECOME MORE
CHALLENGING AFTER THURSDAY WITH REGARDS TO SFC TEMPERATURES AS WELL
AS LAKE EFFECT POTENTIAL. MED RANGE MODELS CONSISTENT WITH REGARDS
TO -28 TO -34 C CORE OF 850 TEMPS ACCOMPANYING DEEP UPPER LOW.
HOWEVER...WHERE THIS WILL END UP IS LESS CERTAIN. 12Z RUNS OF GFS
AND ECMWF WERE MORE TOWARDS THE NE STATES. 00Z GFS HOLD WITH THIS
IDEA, BUT 00Z ECMWF BRINGS CORE OF COLD AIR INTO THE EASTERN GREAT
LAKES. AT THIS POINT...WILL MAINTAIN PREVIOUS IDEA OF SLGT CHC TO
CHC POPS CLOSER TO THE LAKE. ENOUGH CONFIDENCE IN COLDER TREND TO
LOWER TEMPS A FEW DEGREES FRI INTO SAT. IF CORE OF COLDER AIR DOES
COME FURTHER WEST...THEN A SIGNIFICANT DROP IN TEMPS WILL BE
WARRANTED.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1228 AM EST MON FEB 8 2016

AN UPPER LEVEL VORT MAX ACROSS SOUTHEAST IOWA WILL DIG ACROSS THE
MID MS VALLEY OVERNIGHT. GUIDANCE CONTINUES TO DEPICT BEST CHANCES
OF DOWNSTREAM MID LEVEL FRONTOGENESIS FORCING KEEPING CHANCES OF
LIGHT RAIN EAST OF KFWA THROUGH THE OVERNIGHT HOURS. FRONTAL
BOUNDARY ASSOCIATED WITH THE UPSTREAM VORT MAX WILL TRACK ACROSS
NORTHERN INDIANA MONDAY MORNING/AFTERNOON BRINGING A LIKELIHOOD OF
SNOW SHOWERS. PERIODIC IFR VSBYS ARE A POSSIBILITY AT KSBN LATE
MORNING-MIDDAY...AND AT KFWA DURING THE AFTERNOON. A NARROW WINDOW
OF LOWER SNOW SHOWER PROBS MAY SETUP LATE MONDAY AFTERNOON/MONDAY
EVENING BEFORE ANOTHER VORT LOBE DROPS SOUTHWARD ACROSS THE
SOUTHERN GREAT LAKES BRINGING RENEWED SNOW SHOWER POTENTIAL TOWARD
THE END OF THIS FORECAST VALID PERIOD. SOUTHWEST WINDS OF AROUND
10 KNOTS WILL BECOME WEST-NORTHWEST 10 TO 15 KNOTS MONDAY...WITH
SOME GUSTS APPROACHING 20 KNOTS A POSSIBILITY DURING THE
AFTERNOON.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 1 AM TUESDAY TO 10 AM EST THURSDAY FOR
     LMZ043-046.

&&

$$

SYNOPSIS...FISHER
SHORT TERM...MURPHY
LONG TERM...FISHER
AVIATION...MARSILI


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