Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 091146
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
646 AM EST TUE FEB 9 2016

.SYNOPSIS...
ISSUED AT 645 AM EST TUE FEB 9 2016

LAKE EFFECT SNOW SHOWERS ARE EXPECTED TO INCREASE IN COVERAGE AND
INTENSITY LATE TODAY. THE SNOW SHOWERS WILL BE HEAVIEST LATE
TONIGHT INTO WEDNESDAY MORNING WITH 1 TO 2 INCH PER HOUR RATES IN
THE STRONGEST BANDS. THEN THE SNOW SHOWERS WILL LESSEN IN
INTENSITY BUT STILL PERSIST ALL THE WAY INTO MIDDAY THURSDAY.
WHILE MOST LOCATIONS SHOULD SEE AT LEAST SOME MEASURABLE SNOWFALL
DURING THIS PERIOD...THE MORE SIGNIFICANT AMOUNTS AND GREATEST
IMPACTS WILL BE CONFINED TO THE FAVORED LAKE EFFECT REGION OF FAR
NORTHERN INDIANA AND SOUTHWESTERN LOWER MICHIGAN.

&&

.SHORT TERM...(TODAY THROUGH THURSDAY)
ISSUED AT 459 AM EST TUE FEB 9 2016

MULTIPLEX MID/ULVL VORTEX HAS BEEN SLOW TO DEPART WITH STRONG
NOAM BLOCK AND MULTITUDE OF STRONG DIGS OF UPSTREAM ENERGY. UNTIL
OFFSHORE NEW ENGLAND COASTAL STORM LIFTS NNEWD INTO MARITIMES AND
FINAL 160KT UPSTREAM 3H JETLET OVER SASK DIVES DIVES SWD INTO IA
THIS EVENING THE OVERALL STACKED SYSTEM THERMODYNAMICS TO PROVE
DISFAVORABLE FOR LES. STILL MORE SYNOPTICALLY DRIVEN SHSN WITH
DEEP MOISTURE TO 15KFT TO CONTINUE TODAY. WILL CONTINUE TO COVER
SUBADVISORY HAZARDS DUE TO LIGHT SNOW ACCUMS/GROUND ICE WITH SPS
PRODUCT AS NEEDED. BY LATE AFTERNOON/EVENING WILL HAVE RAPID
ARRIVAL OF 8H COLD POOL CURRENTLY IN HOLDING PATTERN ACROSS NWRN
WI/FAR WRN LK SUPR WITHIN CONGESTED FLOW. OUTPUT FROM 1.33KM/HIGH
IMPACT NAM NEST FURTHER CONFIRMS MORE GENERAL CONCEPTUAL AND OTHER
NAM/MULTICOBB MODEL SUGGESTIONS AND POINT TO 21 UTC TUE FOR START
OF A MORE COHESIVE LES EVENT AND START TIME FOR WINTER WX ADVISORY
FOR LES. PER HIGH RES OUTPUT...INITIAL PRIMARY BAND FORMATION ACRS
SRN LAKE MI INTO BERRIEN/NERN LAPORTE LATE AFTERNOON/EVE.
THEREAFTER A SECONDARY MORE NORTHWARD CONVECTIVE ROLL/LES BAND
FORMS WHILE A THIRD BAND FORMS CLOSER TO EAST CENTRAL LAKE
MICHIGAN SHORELINE AND DROPS SOUTH TAKING ON A KLUD TO NRN ST. JOE
MI COUNTY TARGET. REGARDLESS OF ACTUAL EVOLUTION INTENSITY
OF/CONVECTIVE DEPTH/SUPERSATURATION WITHIN 3KFT DGZ SHOULD LEAD TO
BRIEFLY PEAKED SNOWFALL RATES OF ONE TO TWO INCHES PER HOUR LATE
TONIGHT INTO EARLY WED WITH BEST INGREDIENTS OVERLAP AND DELTA T
TO 20C. THEREAFTER AS LOWER PART OF DGZ GOES SUBCLOUD RATES TO
DIMINISH. STILL SLOW DISINTEGRATION OF LES AGGREGATE TROF AND NEAR
STEADY STATE LAKE INDUCED PARAMETERS OF 350-400 J/KG AND 6-7KFT
EQL TO MAINTAIN A PROLONGED EVENT FOR REMAINDER OF WED INTO THU
AM. TARGETED PATCHY BLOWING SNOW IN HEART OF HIGHEST EXPECT ACCUMS
TONIGHT AND WED. THEREAFTER RATES AND SFC WIND SPEEDS SHOULD
GREATLY LESSEN OCCURRENCE. LARGELY OWING TO THE LACK OF A DEEPER
DGZ AND DOWNTREND IN MULTIMODEL AVERAGED COBB METHOD SNOW AMOUNTS
HAVE TEMPERED AMOUNTS OVER PRIOR SOMEWHAT. LONGEVITY OF EVENT
SHOULD LEAD TO 6 TO 12 INCHES ESPECIALLY IN BERRIEN/WRN CASS
COUNTIES MICHIGAN AND ST. JOE AND EXTREME NERN LAPORTE COUNTIES
INDIANA. MIN WIND CHILLS 5 BLO TO 5 ABV TONIGHT THROUGH END OF
ADVISORY ADDS ADDITIONAL HAZARD.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH MONDAY)
ISSUED AT 459 AM EST TUE FEB 9 2016

LAKE EFFECT SNOW SHOWERS SHOULD DIMINISH AS INVERSION HEIGHTS
LOWER AND WINDS BACK IN RESPONSE TO THE NEXT WAVE RAPIDLY MOVING
SE TOWARDS THE REGION. LIGHT ACCUMULATIONS MAY BE IN STORE DURING
THE DAY FRIDAY WITH TRANSITION BACK TO LAKE EFFECT SNOW SHOWERS
FRIDAY NIGHT.

MORE PRONOUNCED LAKE RESPONSE WILL LIKELY TAKE PLACE SATURDAY
INTO MONDAY AS ARCTIC LOW DROPS INTO NEW ENGLAND FOR THE WEEKEND
AND SENDS TEMPERATURES PLUMMETING ACROSS THE AREA. MODELS NOW SEEM
TO BE IN AGREEMENT ON BULK OF COLDEST AIR STAYING EAST OF HERE,
BUT STILL PLENTY LOW ENOUGH TO END UP WITH HIGHS IN THE LOW TO MID
TEENS FOR SATURDAY. POTENTIAL EXISTS FOR ACCUMULATING SNOWFALL
AGAIN ACROSS THE AREA...BUT GIVEN CONCERNS AS TO EXACTLY HOW
MOISTURE PROFILES AND TRAJECTORIES WILL SET UP...LITTLE MORE THAN
CHC POPS WARRANTED.

WITH TRENDS BEING FURTHER EAST WITH THE COLDER AIR...MOS GUIDANCE
HAS TRIED TO INCREASE TEMPERATURES SEVERAL DEGREES. HAVE WENT WITH
BLEND OF PREVIOUS FORECAST AND NEW SUPERBLEND DATA TO HOLD DOWN
MASSIVE CHANGES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 637 AM EST TUE FEB 9 2016

BRIEF SNYOPTICALLY DRIVEN SHSN CONTINUE THIS AM WITH PRIMARILY
FUEL/ALT CRITERIA TO OCNLY LOWER IFR VSBY/CIGS ACROSS NORTHERN
INDIANA. A BRIEF LULL IS EXPECTED THIS AFTERNOON BEFORE
INCREASINGLY MORE DEVELOPED LAKE EFFET BANDS FORM AND PRIMARILY
AFFECT KSBN. BY DAYBREAK ANTICIPATE LAKE BANDS TO BE AT/NEAR
PINACLE WITH OCNL LIFR WITHIN HEART OF BANDS.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY FROM 4 PM EST /3 PM CST/ THIS AFTERNOON
     TO 10 AM EST /9 AM CST/ THURSDAY FOR INZ003>005.

MI...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 10 AM EST
     THURSDAY FOR MIZ077>079.

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

&&

$$

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


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