Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 130820
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
420 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 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 132 AM EDT SAT SEP 13 2014

A STRONG UPPER LEVEL TROUGH ACROSS THE MID MISSISSIPPI VALLEY WILL
TRACK ACROSS THE SOUTHERN GREAT LAKES REGION
OVERNIGHT...EVENTUALLY TAKING BRUNT OF RAINFALL EAST OF THE AREA.
AN ADDITIONAL 2 TO 4 HOURS OF RAIN IS EXPECTED AT KSBN IN
ASSOCIATION WITH THE SYNOPTIC SYSTEM...WHICH MAY EXTEND INTO THE
12Z TIMEFRAME WITH LINGERING LAKE EFFECT RAIN SHOWERS. GIVEN TRACK
OF STRONGEST UPPER FORCING...A SHORTER DURATION OF PRECIP IS
EXPECTED AT KFWA AND ONLY CHANGE FROM PREVIOUS TAFS WAS TO
SLIGHTLY MOVE UP TEMPO -SHRA GROUP AT KFWA TO THE 08Z TO 11Z
TIMEFRAME. PRIMARILY MVFR CIGS ARE EXPECTED...ALTHOUGH SOME SHORT
LIVED IFR CIGS APPEARS TO BE A POSSIBILITY AT KSBN IN THE 06Z-09Z
TIMEFRAME. LOW CLOUDS ARE EXPECTED TO BECOME MORE BROKEN IN NATURE
LATE MORNING OR TOWARD MIDDAY...WITH DRY AIR ADVECTION BEHIND
SYSTEM LENDING TO SCT-BKN VFR CLOUD BASED IN THE AFTERNOON.
NORTHWEST WINDS AROUND 10 KNOTS WILL BECOME LIGHT AND VARIABLE
TONIGHT AS A BROAD RIDGE OF HIGH PRESSURE SETTLES INTO THE REGION.
SOME PATCHY SHALLOW FOG IS A POSSIBILITY LATE SATURDAY NIGHT WHICH
MAY NEED TO BE CONSIDERED FOR THE 12Z TAF ISSUANCE.

&&

.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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