Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 261522
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1122 AM EDT WED AUG 26 2015

.SYNOPSIS...
ISSUED AT 1109 AM EDT WED AUG 26 2015

SPRINKLES TO LIGHT SHOWERS ARE POSSIBLE TODAY IN NORTHERN INDIANA
SOUTHERN MICHIGAN AND NORTHWESTERN OHIO AS A LOW STILL ROTATES IN
CANADA AND HIGH PRESSURE IS TO THE NORTHWEST. THIS HIGH WILL MOVE
INTO THE REGION TONIGHT CLEARING UP THE SKIES. HIGH TEMPERATURES
TODAY WILL RANGE FROM THE UPPER 60S IN SOUTHERN MICHIGAN TO THE
MIDDLE 70S NEAR THE OHIO RIVER. LOWS TONIGHT WILL BE ON THE COOL
SIDE IN THE LOWER 50S.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 404 AM EDT WED AUG 26 2015

HIGHLY AMPLIFIED MID/UPR FLOW ACROSS CONUS AT PRESENT
CHARACTERIZED BY TX PANHANDLE TO ERN MT RIDGE BETWIXT SHARP/SLOWLY
EXITING TROF ACROSS SERN CANADA INTO LOWER GREAT LAKES AND 140W
CENTERED TROF. WHILE STRONG SHORTWAVE TO OVERTOP/DERIDE UPSTREAM
RIDGE OVER NEXT 24 HOURS...LOW LEVEL FLOW/TEMPERATURE PROFILES TO
REMAIN LARGELY STATUS QUO TODAY/TONIGHT. MINOR CHANGES TO ONGOING
FORECAST INCLUDE...SLIGHT LOWERING OF TEMPS THROUGH TODAY ALONG WITH
INCREASED CLOUD COVER/LOW POP AND/OR SPRINKLES MENTION ACROSS
NORTHERN TIER. 925-8H RIDGE WELL UPSTREAM OVER MISSOURI RIVER VALLEY
TO MAKE ONLY SLIGHT EWD PROGRESS TODAY. MAINTENANCE OF STRATOCU
APPEARS FAVORABLE WITH CYCLONIC LOW LEVEL FLOW INTO MIDDAY/AFTN
BEFORE WANING. FURTHERMORE...CORE OF THERMAL TROF THROUGH CWA AND
UPSTREAM MID LEVEL SHORTWAVES ENTERING BASE OF TROF BODES WELL FOR
SLOWER CLEARING TREND. CLOUD COVER TO QUICKLY DERIDE THIS EVENING AS
DEEP LAYER SUBSIDENCE OVERWHELMS AMID RELAXING LOW LEVEL FLOW.
SELECTIVE DOWNWARD NUDGES TO MIN TEMPS IN FAVORED DRAINAGE REGIONS
INCLUDING LAKESHORE/KBEH/KOXI/KGSH SITES.

&&

.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 404 AM EDT WED AUG 26 2015

LOW LEVEL THERMAL TROUGHING WILL HOLD FOR ONE MORE DAY ON
THURSDAY...AS UPPER LEVEL TROUGHING BEGINS TO DEPART THE OHIO
VALLEY. LOW LEVEL AIR MASS WILL CONTINUE TO MODIFY THURSDAY AS MID
LEVEL HEIGHTS BEGIN TO RISE. DIURNALLY ENHANCED STRATOCU APPEARS
TO BE MOST LIKELY ACROSS EASTERN AREAS...BUT OTHERWISE A GOOD DEAL
OF INSOLATION IS EXPECTED FOR THE REMAINDER OF THE AREA. TAKING
THE ABOVE FACTORS INTO ACCOUNT...EXPECTING AT LEAST A COUPLE OF
DEGREES OF MODERATION IN COMPARISON TO WEDNESDAY...WITH HIGHS
GENERALLY IN THE MID 70S. DRY AIR MASS IN PLACE/CLEAR SKIES WILL
ALLOW FOR IDEAL RADIATIONAL COOLING CONDITIONS ONCE AGAIN THURSDAY
NIGHT WITH LOWS DROPPING WELL INTO THE 50S.

FOR FRIDAY-SUNDAY ATTENTION WILL TURN TO UPPER LEVEL TROUGH EJECTING
OUT OF BAJA OF CALIFORNIA REGION. THIS TROUGH SHOULD GET REINFORCED
BY AN UPPER PV ANOMALY DROPPING SOUTHEAST OUT OF NORTHERN STREAM.
THIS CONSOLIDATED PV ANOMALY IS THEN EXPECTED TO AFFECT THE LOCAL
AREA FOR THE FRIDAY NIGHT-SUNDAY PERIOD...ALTHOUGH VARIOUS
DETERMINISTIC SOLUTIONS STILL EXHIBITING QUITE A SIGNIFICANT SPREAD
IN TERMS OF STRENGTH OF THIS FEATURE WHICH IS SOMEWHAT DEPENDENT ON
EXTENT OF UPSTREAM PHASING. NONETHELESS...AN UPSWING IN ISENTROPIC
LIFT IS EXPECTED LATE FRIDAY AFTERNOON/NIGHT IN ADVANCE OF THIS
TROUGH. LOW LEVEL MOISTURE IS EXPECTED TO REMAIN RATHER MEAGER INTO
FRIDAY NIGHT AS MORE VEERED LOW LEVEL FLOW MAY INITIALLY NOT BE
EFFECTIVE IN SUBSTANTIAL MOISTURE TRANSPORT GIVEN HISTORY OF
SYNOPTIC SUBSIDENCE OF UPSTREAM AIRMASS. THUS...HAVE OMITTED THUNDER
FROM FRIDAY NIGHT AND JUST MAINTAINED LOW CHANCE SHRA POPS ACROSS
THE NORTH IN ASSOCIATION WITH ISENTROPIC FORCING.

UNSETTLED PATTERN TO CONTINUE SATURDAY/SUNDAY AS THIS PV ANOMALY
SLOWLY ERODES/ATTENUATES ACROSS THE REGION. BEST CHANCES OF THUNDER
SHOULD BE SATURDAY AFTERNOON ACROSS THE EAST...ALTHOUGH SOME ISOLD
THUNDER CANNOT BE RULED OUT THROUGH MOST OF THE UPCOMING WEEKEND.
IMPACTS OF CLOUDS/SCT SHOWERS SHOULD LIMIT HIGHS TO UPPER 70S OR
AROUND 80.

NO MAJOR CHANGES FOR THE REMAINDER OF FORECAST WITH UPPER RIDGING
BUILDING BACK ACROSS THE REGION AND A STEADY WARMING TREND THROUGH
THE MIDDLE OF NEXT WEEK.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)
ISSUED AT 554 AM EDT WED AUG 26 2015

SEVERAL PERTURBATIONS ROTATING AROUND PARENT WESTERN QUEBEC UPPER
LOW HAVE MAINTAINED MID LEVEL COLD CORE ACROSS THE WESTERN GREAT
LAKES REGION THIS MORNING. THE COMBINATION OF THIS FORCING ALONG
WITH NOCTURNAL COOLING AND ONSHORE TRAJECTORIES HAVE SUPPORTED THE
FORMATION OF MVFR CIGS ACROSS NORTHWEST/NORTH CENTRAL INDIANA THIS
MORNING. WILL STAY WITH BASIC PREMISE OF PREVIOUS FORECAST WITH
MVFR CIGS PERSISTING AT KSBN TODAY. A BRIEF PERIOD OF CIGS BELOW
2K FT CANNOT COMPLETELY BE RULED OUT IN THE 12Z-14Z
TIMEFRAME...BUT CONFIDENCE LIKELY WILL BE TOO LOW FOR 12Z TAF
INCLUSION. SFC HIGH TO OVERSPREAD THE AREA TONIGHT WITH CLEARING
SKIES EXPECTED...ALONG WITH DIMINISHING WINDS. THIS MAY ALSO
SUPPORT SOME PATCHY FOG FORMATION TOWARD THE END OF THE
PERIOD...BUT WILL MAINTAIN VFR CONDITIONS GIVEN LOWER CONFIDENCE
AT TERMINALS AT THIS FORECAST DISTANCE.


&&

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

$$

SYNOPSIS...LOTHAMER
SHORT TERM...MURPHY
LONG TERM...MARSILI
AVIATION...MARSILI


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