Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 220532
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1232 AM EST THU JAN 22 2015

.SYNOPSIS...
ISSUED AT 726 PM EST WED JAN 21 2015

A COUPLE OF WEAK UPPER LEVEL DISTURBANCES WILL CONTINUE TO TRACK
ACROSS THE REGION TONIGHT INTO EARLY THURSDAY MORNING...PROVIDING
A CHANCE OF LIGHT SNOW SHOWERS. BY THURSDAY MORNING...ANY
LINGERING LIGHT SNOW SHOWERS SHOULD BE CONFINED TO SOUTHWEST LOWER
MICHIGAN AND NORTHWEST INDIANA...WITH DRY CONDITIONS EXPECTED
THURSDAY AFTERNOON THROUGH SATURDAY. LOWS TONIGHT WILL BE IN THE
LOWER TO MIDDLE 20S... WITH HIGHS THURSDAY MAINLY IN THE LOWER
30S.

&&

.UPDATE...
ISSUED AT 840 PM EST WED JAN 21 2015

SEVERAL EMBEDDED SMALLER SCALE WAVES WILL CONTINUE TO TRACK ACROSS
SOUTHERN GREAT LAKES AND OHIO VALLEY OVERNIGHT...BUT WILL REMAIN
WEAK IN NATURE AS THEY ENCOUNTER STRONG UPPER LEVEL DEFORMATION
AXIS ACROSS THE REGION. STRONGEST SYNOPTIC FORCING IS NOW SLIPPING
SOUTHEAST OF LOCAL AREA ALTHOUGH WEAKER WAVES ACROSS THE
SOUTHERN GREAT LAKES COMBINED WITH WEAK INVERTED TROUGH FEATURE
HAS ALLOWED FOR SOME PATCHY LIGHT SNOW/DRIZZLE/FREEZING DRIZZLE TO
PERSIST ACROSS SOUTHERN LOWER MICHIGAN/NORTHERN INDIANA WITH
CONTINUED MARGINAL PROFILES IN TERMS OF -SN/DZ. HAVE HAD A FEW
REPORTS ACROSS EXTREME NORTHEAST INDIANA AND SOUTHERN LOWER
MICHIGAN OF A VERY LIGHT GLAZE DEVELOPING WITH SOME OF THE
DRIZZLE. WEAK LOW LEVEL DRY AIR ADVECTION SHOULD CONTINUE
OVERNIGHT AND EXPECTING THREAT OF FREEZING DRIZZLE TO BEGIN TO
DIMINISH AFTER 05Z. GIVEN VERY LIGHT NATURE TO PRECIP AND RELATIVE
SHORT DURATION OF THREAT...HAVE HANDLED THIS WITH AN SPECIAL
WEATHER STATEMENT TO EMPHASIZE POSSIBILITY OF ISOLATED SLICK
CONDITIONS...MAINLY SOUTHERN LOWER MICHIGAN...NORTHEAST
INDIANA...AND NORTHWEST OHIO. OTHERWISE...MAINTAINED IDEA FROM
PREVIOUS FORECAST IN DIMINISHING SNOW SHOWER POPS OVERNIGHT...WITH
SLIGHT/CHANCE POPS PERSISTING THE LONGEST DOWNWIND OF LAKE
MICHIGAN WHERE SOME WEAK LAKE EFFECT PRECIP IS POSSIBLE.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY)
ISSUED AT 256 PM EST WED JAN 21 2015

SHRTWV/WK SFC LOW MOVG EAST ALONG STNRY FRONTAL BOUNDARY ACROSS THE
AREA THIS AFTN. CONVERGENCE AND WK STABILITY ALONG FRONT SUPPORTING
A BAND OF SNOW ACROSS SRN PORTION OF THE AREA WHICH HAS BEEN LIFTING
SLOWLY NORTH. BAND EXPECTED TO SHIFT BACK SE LATE THIS AFTN AS
SHRTWV/LOW PASSES. GIVEN LIMITED DEEP MOISTURE AND SMALL DGZ...
EXPECTING SNOW ACCUMS WILL BE LESS THAN AN INCH IN THIS AREA. SGFNT
LIFT SHOULD BE EAST OF THE CWA BY 00Z BUT MOIST LOW LEVELS AND
CYCLONIC FLOW MAY SUPPORT SOME SNOW SHOWERS ACROSS THE AREA
OVERNIGHT... AND INTO FRIDAY MORNING NEAR LAKE MICHIGAN AS NW FLOW
AND WK LAKE INDUCED INSTABILITY RETURNS. DVLPG SUBSIDENCE INVERSION
AND RATHER WK LOW LEVEL FLOW SHOULD RESULT IN MOSTLY CLOUDY SKIES
CONTG THU. WITH EXPECTED PERSISTENT CLOUD COVER... DIURNAL TEMP
RANGES FCST A LITTLE UNDER MOS GUIDANCE WITH LOWS TONIGHT IN THE
L-M20S AND HIGHS THU MAINLY IN THE L30S.

&&

.LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 256 PM EST WED JAN 21 2015

A STRONG SOUTHERN STREAM SYSTEM WILL PASS FAR TO THE SOUTHEAST AND
EAST OF THE FORECAST AREA SATURDAY...KEEPING ALL PRECIPITATION AWAY
FROM THE FORECAST AREA. AFTER THIS SYSTEM...THE NEXT CHALLENGE IS A
CLIPPER SYSTEM WHICH IS EXPECTED TO REACH THE FORECAST AREA SUNDAY.
THE LATEST MODEL BLEND WAS QUITE INDISCRIMINATE WITH THE FORECAST
CHANCES FOR PRECIPITATION ON SUNDAY. GIVEN THE LATEST MODEL
TRENDS...CIPS ANALOGS AND CLIPPER CLIMATOLOGY...FORECAST THE BEST
CHANCES FOR SNOW OVER NORTHERN AREAS INCLUDING FAR SOUTHERN LOWER
MICHIGAN AND EXTREME NORTHERN INDIANA AND NW INDIANA. EXPECT A BAND
OF 2 TO 4 INCHES OF SNOW OVER THIS AREA...WITH LESSER AMOUNTS
FARTHER SOUTH. FOR MONDAY THROUGH WEDNESDAY...THE TEMPERATURE
FORECAST IS VERY CHALLENGING INCLUDING A TIGHT THERMAL GRADIENT FROM
SOUTHWEST TO NORTHEAST...FURTHER COMPLICATED BY THE PASSAGE OF
ANOTHER CLIPPER SYSTEM. TENDED TO GO AWAY FROM THE LATEST MODEL
BLEND WHICH CONTINUES TO MAKE LARGE CHANGES FROM RUN TO RUN WHICH
TRIES TO INCORPORATE THE LATEST MODEL HANDLING OF THE ARCTIC AIR .
TEMPERATURES SHOULD BE AT LEAST A LITTLE BELOW NORMAL WITH THIS
PATTERN.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 1224 AM EST THU JAN 22 2015

AREA OF DZ/FZDZ THAT WAS OVER NORTHEAST INDIANA IS DIMINISHING IN
COVERAGE AS SUBSIDENCE AND DRIER AIR WORK INTO THE REGION. BASED
ON LATEST KIWX RADAR LOOP OPTED TO NOT INTRODUCE ANY ADDITIONAL
PCPN INTO KFWA TAF THOUGH CANNOT RULE OUT A VERY BRIEF PERIOD OF
DRIZZLE IN NEXT HOUR OR TWO. OTHERWISE STRONG TEMPERATURE
INVERSION HAS HELPED LOCK IN CLOUD DECK ACROSS THE GREAT LAKES
REGION AND THIS LIKELY TO PERSIST THROUGH THE PERIOD. MAY SEE CIGS
RISE A FEW HUNDRED FEET THIS AFTERNOON AND SOME BREAKS DEVELOP
WITH SUBSIDENCE AND DRIER AIR WORKING IN. HOWEVER...GIVEN TIME OF
YEAR AND CLIMATOLOGY ALONG WITH LATEST MODEL SOUNDINGS OPTED TO
KEEP MVFR CIGS IN PLACE THROUGH END OF PERIOD.

&&

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

$$

UPDATE...MARSILI
SYNOPSIS...MARSILI
SHORT TERM...JT
LONG TERM...SKIPPER
AVIATION...LASHLEY


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