Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 131042
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
642 AM EDT SAT SEP 13 2014

.SYNOPSIS...
ISSUED AT 418 AM EDT SAT SEP 13 2014

DECREASING CLOUDS CAN BE EXPECTED TODAY AS AN UPPER LEVEL
DISTURBANCES EXITS THE REGION...BUT UNSEASONABLY COOL CONDITIONS
WILL PERSIST ACROSS THE REGION HOWEVER. A RIDGE OF HIGH PRESSURE
WILL SETTLE ACROSS THE AREA TONIGHT WITH MAINLY CLEAR SKIES AND COOL
TEMPERATURES CONTINUING INTO SUNDAY. THE NEXT CHANCE OF RAIN IS IN
STORE FOR MONDAY AS ANOTHER FAST MOVING SYSTEM TRACK ACROSS THE
GREAT LAKES. HIGH TEMPERATURES THIS AFTERNOON WILL ONLY REACH THE
UPPER 50S TO LOWER 60S. LOW TEMPERATURES TONIGHT WILL RANGE FROM THE
UPPER 30S TO MID 40S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 418 AM EDT SAT SEP 13 2014

A STRONG UPPER LEVEL TROUGH ACROSS THE WESTERN GREAT LAKES WILL
CONTINUE TO BE PROGRESSIVE ACROSS THE REGION EARLY THIS MORNING
ALLOWING FOR RAIN TO DEPART EASTERN PORTIONS OF THE AREA SHORTLY
AFTER 12Z. PRECIP WILL LIKELY END AS A PERIOD OF PATCHY DRIZZLE AS
PRONOUNCED MID LEVEL DRY SLOT ADVECTS EASTWARD ACROSS THE AREA.
DESPITE FAIRLY SUBSTANTIAL LAKE INDUCED INSTABILITY...RAPID ONSET OF
MID LEVEL DRY AIR ADVECTION SHOULD LIMIT DURATION/COVERAGE OF LAKE
EFFECT RAIN SHOWERS THIS MORNING WITH THIS POTENTIAL WANING
ESPECIALLY BY THE 15Z TIMEFRAME. THE BACK EDGE OF STRATUS HAS SHOWN
STEADY EASTWARD PROGRESSION OVERNIGHT ACROSS NORTHERN ILLINOIS WITH
AT LEAST PARTIAL CLEARING EXPECTED TO WORK FROM WEST TO EAST ACROSS
THE AREA THIS MORNING AS POCKET OF STRONG SYNOPTIC SCALE SUBSIDENCE
OVERSPREADS THE AREA IN WAKE OF UPPER TROUGH. SOME POSSIBILITY MAY
EXIST FOR STRATUS TO HOLD A BIT LONGER ACROSS EASTERN TWO THIRDS OF
THE AREA THIS MORNING DUE TO STRENGTH OF INVERSION...BUT WOULD
EXPECT MOST AREAS TO TREND TO PARTLY CLOUDY TO MOSTLY SUNNY SKIES
THIS AFTERNOON. LOW LEVEL AIR MASS MAY ACTUALLY BE A BIT COOLER
TODAY WITH WEAK REINFORCING LOW LEVEL CAA THIS MORNING...BUT WOULD
EXPECT THAT INCREASED INSOLATION TODAY WILL BALANCE THIS OUT AND
PERHAPS EVEN PROVIDE MAX TEMPS JUST SLIGHTLY WARMER THAN
YESTERDAY...BUT OBVIOUSLY CONTINUED MUCH BELOW NORMAL FOR MID
SEPTEMBER. RECORD FOR LOW MAX TEMPERATURES FOR THE DATE AT KSBN IS
56 SET IN 1989 AND AT KFWA 57 SET IN 1923. WHILE CURRENTLY NOT
FORECASTING THAT THESE RECORDS WILL BE BROKEN...KSBN COULD BE CLOSE
IF STRATUS HOLDS A BIT LONGER THAN EXPECTED TODAY.

FOR TONIGHT...BROAD ANTICYCLONE TO OVERSPREAD THE AREA WILL ALLOW
FOR DECOUPLING EARLY THIS EVENING AND LIGHT AND VARIABLE WINDS.
MAINLY CLEAR SKIES TONIGHT AND LIGHT WINDS WILL PROVIDE GOOD
RADIATIONAL COOLING CONDITIONS...AND WITH TRAPPED LOW LEVEL MOISTURE
DUE TO INVERSION PAST FEW DAYS...CROSSOVER TEMPS MAY END UP BEING
HIGH ENOUGH TO REALIZE SOME PATCHY SHALLOW GROUND FOG LATE TONIGHT
INTO EARLY SUNDAY MORNING. THIS POTENTIAL WILL DEPEND SOMEWHAT ON
STRATUS/MIXING TRENDS THIS AFTERNOON SO WILL HOLD OFF ON ANY MENTION
AT THIS TIME. MINS FOR TONIGHT SHOULD RANGE FROM UPPER 30S TO LOWER
40S...AND WITH LAND BREEZE EXPECTED TO FORM NOT EXPECTING MUCH IN
THE WAY OF A SIGNIFICANT LAKE SHADOW IN TERMS OF TEMPS.

&&

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 418 AM EDT SAT SEP 13 2014

THE NEGATIVE HEIGHT ANOMALY WILL REMAIN OVER THE EASTERN CONUS THIS
UPCOMING WEEK...WITH TEMPERATURES REMAINING BELOW NORMAL FOR THIS
TIME OF YEAR. TRENDED LOWS A LITTLE LOWER DURING THE MIDDLE OF THIS
UPCOMING WEEK GIVEN CHILLY 850 MB TEMPS OF GENERALLY 4C TO 6C
SUPPORTED BY BOTH THE GFS AND ECMWF. KEPT CONDITIONS DRY EXCEPT FOR
A CHANCE FOR RAIN MONDAY INTO MONDAY NIGHT. RAISED RAIN CHANCES
MONDAY AFTERNOON GIVEN UPPER LEVEL JET SUPPORT AND REASONABLE
ISENTROPIC LIFT ON THE 305K SURFACE.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 640 AM EDT SAT SEP 13 20`

A STRONG BUT PROGRESSIVE UPPER TROUGH ACROSS THE WESTERN GREAT
LAKES WILL TRACK INTO SOUTHEAST ONTARIO THIS MORNING WITH A POCKET
OF STRONG MID LEVEL SUBSIDENCE IN ITS WAKE. MID LEVEL DRY SLOT IS
CURRENTLY ADVECTING ACROSS NORTHERN INDIANA ALLOWING A TRANSITION
TO PRECIP OF A MORE DRIZZLY VARIETY...OUTSIDE OF LAKE EFFECT RAIN
SHOWERS CURRENTLY NORTH OF KSBN. POTENTIAL OF LAKE EFFECT RAIN
SHOWERS/DRIZZLE SHOULD DIMINISH TOWARD 15Z. PRIMARILY MVFR CIGS
SHOULD TEND TO IMPROVE TO VFR LATER THIS MORNING. CONFIDENCE IN
TIMING SCATTERING OF LOW CLOUD DECK SOMEWHAT LOW AT THIS TIME
GIVEN STRENGTH OF INVERSION...BUT WOULD SUSPECT THAT SYNOPTIC
SUBSIDENCE/DRY AIR ADVECTION WILL ALLOW FOR TRANSITION TO SCT-BKN
VFR BASED LOW CLOUDS AFTER 16Z. SKIES TO BECOME CLEAR TONIGHT WITH
LIGHT WINDS AS BROAD ANTICYCLONE SETTLES INTO THE REGION.
DEPENDING ON STRATUS/MIXING TRENDS TODAY...SOME PATCHY SHALLOW
GROUND FOG WILL BE POSSIBLE LATE TONIGHT...BUT CONFIDENCE TOO LOW
AT THIS TIME TO INCLUDE ANY MVFR MENTION AT THIS FORECAST
DISTANCE.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR INZ003.

MI...BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR MIZ077.

OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ043-046.

&&

$$

SYNOPSIS...MARSILI
SHORT TERM...MARSILI
LONG TERM...SKIPPER
AVIATION...MARSILI


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