Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 180558
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1258 AM EST THU DEC 18 2014

.SYNOPSIS...
ISSUED AT 1240 AM EST THU DEC 18 2014

LIGHT LAKE EFFECT SNOW SHOWERS ARE POSSIBLE TODAY AS A TROF MOVES
SOUTH OVER LOWER MICHIGAN INTO NORTHERN INDIANA. THE WINDS BEHIND
THIS TROF WILL MAKE THE FETCH A LITTLE MORE FAVORABLE FOR LAKE
EFFECT SNOW. HOWEVER...LITTLE IF ANY SNOW ACCUMULATION IS
EXPECTED. HIGHS TODAY AND FRIDAY WILL BE AROUND 30 TO 35. LOWS
THURSDAY NIGHT WILL BE IN THE 20S.

&&

.UPDATE...
ISSUED AT 847 PM EST WED DEC 17 2014

NO SIGNIFICANT CHANGES MADE TO FORECAST THIS EVENING. LIGHT SNOW
HAS DIMINISHED OVER THE PAST FEW HOURS AS MID LEVEL SUBSIDENCE HAS
STRENGTHENED SUBSTANTIALLY WITH PASSAGE OF SHEARED VORT MAX NOW
PUSHING ACROSS THE EASTERN GREAT LAKES. ANOTHER WEAKER UPSTREAM
VORT ROUNDING BROADER UPPER TROUGH SHOULD TRACK ACROSS SOUTHERN
LOWER MICHIGAN DURING THE OVERNIGHT HOURS WHICH MAY AID IN SOME
REDEVELOPMENT OF LIGHT LAKE EFFECT SNOW SHOWERS. UPDATED ZONES
SENT TO ACCOUNT FOR CURRENT POP TRENDS AND LIMITED POPS TO LOW
CHANCE OVERNIGHT. SOME SLIGHT DOWNWARD ADJUSTMENT ALSO MADE TO
MINS...PARTICULARLY ACROSS THE FAR SOUTHWEST WHERE SOME PARTIAL
CLEARING IS POSSIBLE LATE TONIGHT.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 240 PM EST WED DEC 17 2014

CURRENT TROUGH SWINGING ACROSS THE GREAT LAKES THIS EVENING IS
SHOWING SOME EROSION IN THE CLOUD DECK BEHIND IT ACROSS WESTERN
ILLINOIS. THE QUESTION IS HOW FAR EAST THIS PARTIAL CLEARING MOVES
TOWARDS OUR AREA WHILE AT THE SAME TIME SOUTHERN PLAINS CLOUDS
ADVANCE NORTHEAST TOWARD THAT CLEARING PATCH. END RESULT MAY BE
SOME BRIEF AND PARTIAL CLEARING FOR SOME OF THE SOUTHWEST
COUNTIES.

THE LIGHT SNOW THAT HAS BEEN OCCURRING WILL BE CARRIED AS A CHANCE
THROUGHOUT THE NIGHT IN THE SAME AREAS CURRENTLY AFFECTED. STILL
EXPECT NO MORE THAN A LIGHT COVERING OF SNOW AT WORST FOR SOME
AREAS. MAINLY CLOUDY SKY AND FLOW TURNING MORE OFF THE LAKE SHOULD
KEEP MIN TEMPS TO NO LOWER THAN LOWER 20S TONIGHT.

THURSDAY...THE SOUTHERN PLAINS SYSTEM IS DEPICTED BY MOST MODELS
TO WEAKEN AS IT MOVES INTO RIDGE BEHIND CURRENT TROUGH IN OUR
AREA. NET RESULT WILL BE MAINTENANCE OF CLOUD COVER AND LOW THREAT
FOR LIGHT...NON-ACCUMULATING SNOW THURSDAY AFTERNOON. TEMPERATURES
WILL REBOUND LITTLE...CLIMBING NO MORE THAN LOWER 30S IN THE AFTERNOON.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 240 PM EST WED DEC 17 2014

IN THE WAKE OF THURSDAY TROUGH EXITING THE AREA MODELS SHOW HIGH
PRESSURE BUILDING OVER THE GREAT LAKES AND AIR DRYING OUT
SUGGESTIVE OF DIMINISHED CLOUD COVER. HESITANT TO DELVE TO FAR
INTO PARTLY CLOUDY SKY GIVEN PERSISTENCE OF LOW CLOUD DECKS
WITHOUT MUCH WIND TO SCOUR THEM OUT. MINIMUM TEMPS ON TRACK IN
LOW TO MID 20S AND DIDN`T CHANGE MUCH.

FRIDAY MAY SHOW A FEW PEAKS AT THE SUN WITH NO WEATHER TO SPEAK
OF. THIS SHOULD ALLOW MAX TEMPS TO REACH MID AND UPPER 30S UNDER
LIGHT EAST WIND.

FRIDAY NIGHT INTO SATURDAY MODELS CONTINUE THE TREND OF NEXT
APPROACHING SYSTEM TO REACH NO FURTHER NORTH THAN SOUTHERN INDIANA
WITH PRECIPITATION AND AN OVERCAST SKY FOR OUR AREA.

HIGH PRESSURE WILL ESSENTIALLY REMAIN IN CONTROL FROM FRIDAY NIGHT
INTO MONDAY AFTERNOON. BEYOND THAT TIME FRAME FAIRLY SIGNIFICANT
SYSTEM IS EXPECTED TO MOVE INTO MIDWEST BUT LATEST TRENDS ARE A
BIT WARMER LEANING TO MORE RAIN THAN SNOW. WITH HIGH UNCERTAINTY
AT TIMES WILL KEEP A RAIN SNOW MIX START CONVERTING TO ALL RAIN BY
TUESDAY THEN BACK TO A MIX OR ALL SNOW WEDNESDAY. AGAIN
UNCERTAINTY IS HIGH AND MANY MORE MODEL RUNS SHOULD SORT THIS OUT.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1209 AM EST THU DEC 18 2014

KEPT MVFR CIGS THE ENTIRE TAF PERIOD AT BOTH SBN AND FWA WITH WEST
WINDS 7-10 KTS. EARLY EVENING UPPER AIR SOUNDINGS AND OVERNIGHT
AIRCRAFT OBSERVATIONS SHOW AN INCREASING DEPTH TO THE FRONTAL
INVERSION FROM SOUTHWEST TO NORTHEAST. AN AIRCRAFT SOUNDING AT FWA
AT 0316Z SHOWED THE BASE OF THE SUBSIDENCE INVERSION AROUND 850
MB...OR ABOUT 4000 FT ABOVE THE SFC. GIVEN UPSTREAM MOISTURE BELOW
THE INVERSION...A CONTINUED NORTHWEST TO NORTH FETCH AND THE
ADDITIONAL OF SOME LAKE MOISTURE...BELIEVE IT WILL BE DIFFICULT TO
BREAK OUT OF THE MVFR SC DECK FOR THE NEXT 24 HOURS. THEREFORE...
HAVE KEPT MVFR CIGS THE ENTIRE PERIOD.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 11 AM EST THIS MORNING FOR LMZ043-046.

&&

$$

UPDATE...MARSILI/SKIPPER
SYNOPSIS...MARSILI
SHORT TERM...TUCEK
LONG TERM...TUCEK
AVIATION...SKIPPER


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