Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 251903
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
303 PM EDT TUE AUG 25 2015

.SYNOPSIS...
ISSUED AT 1030 AM EDT TUE AUG 25 2015

LINGERING CLOUDS ASSOCIATED WITH A DEEP LOW PRESSURE AREA WILL
PERSIST THROUGH THE REST OF TODAY INTO TONIGHT. A FEW SPRINKLES OR
LIGHT SHOWERS ARE POSSIBLE...ESPECIALLY OVER NORTHERN AREAS
INCLUDING FAR SOUTHERN LOWER MICHIGAN. HIGHS THIS AFTERNOON WILL
BE FROM 65 TO 70. LOWS TONIGHT SHOULD BE FROM 50 TO 55. HIGHS
WEDNESDAY SHOULD BE AROUND 70.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 259 PM EDT TUE AUG 25 2015

TROF/SFC LOW WILL CONTINUE TO CHURN OVER THE GREAT LAKES THROUGH
THE DAY WEDNESDAY. ALREADY BEGINNING TO SEE THE TROF AXIS SHIFTING
AND NARROWING AS RIDGING STARTS BUILDING TO THE WEST. ANOMOLOUSLY
COLD SYSTEM FOR THIS PERIOD WITH SEVERAL SHORT WAVES AND WEAK
SURFACE BOUNDARIES ACROSS THE WESTERN PORTION OF THE TROF. THIS IS
EVIDENT BY SEVERAL AREAS OF ENHANCED LOW CLOUDS ACROSS LAKE
MICHIGAN. AHEAD OF THESE WAVES...SUSTAINED WINDS INCREASE AN THERE
IS A MARKED INCREASE IN GUST OCCURRENCE. AS THE TROF BEGINS TO
LIFT EAST...BECOMING MORE OF A DEFORMATION AXIS THE FLOW WILL
SHIFT FROM THE WEST-NORTHWEST TO MORE NORTH-NORTHEAST OVERNIGHT.

AS A RESULT HAVE DECREASED POP/WX/QPF FOR THE FIRST 12 HOURS...WITH
A SLIGHT INCREASE IN POPS AND A CHANGE IN THE ORIENTATION OF THE
PRECIP/CLOUD COVER TO AFFECT FURTHER SOUTH AND BE FOCUSED ALONG THE
COUNTIES SOUTH OF LAKE MICHIGAN DURING THE OVERNIGHT AND DURING THE
DAY WEDNESDAY.

THROUGH THIS PERIOD THE DIURNAL TEMPERATURE CURVE IS REALLY
DIFFICULT TO PIN DOWN. THERE IS A 7 TO 12 DEGREE DIFFERENCE BETWEEN
THE CLOUD COVERED AREAS AND CLOUD FREE AREAS TODAY. EXPECT TO SEE
NOMINAL TEMPERATURE DROP IN THE CLOUDY AREAS TONIGHT...ON THE ORDER
OF 5 TO 10 DEGREE CHANGE FROM THE DAYTIME HIGHS. MUCH STEEPER
DIURNAL TREND FOR THE CLOUD FREE AREAS. DURING THE LATE AFTERNOON
WEDNESDAY...EXPECT TO SEE MORE BREAKS IN THE CLOUDS AND WARM
ADVECTION OVERSPREADS FROM SOUTHWEST TO NORTHEAST LATE IN THE DAY.
HAVE GONE WITH A 10 TO 15 DEGREE DIURNAL...BUT THAT MAY BE VERY VERY
OPTIMISTIC IN THE NORTHERN TIER COUNTIES.

&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 259 PM EDT TUE AUG 25 2015

UPPER LOW WILL FINALLY PROGRESS EASTWARD BY THE BEGINNING OF THE
LONG TERM PERIOD WITH BUILDING HEIGHTS AND SURFACE HIGH PRESSURE
IN ITS WAKE KEEPING THE WEATHER FAIR ACROSS OUR FORECAST AREA
THROUGH THE END OF THE WEEK.

THE SYSTEM WHICH WILL AFFECT OUR AREA THIS WEEKEND CAN BE SEEN ON
WATER VAPOR IN THE FOUR CORNERS REGION AS OF 18Z TODAY. THIS WAVE
WILL TRAVERSE THE RIDGE AND AMPLIFY IN THE LEE OF THE ROCKIES BY
THURSDAY. AS THE SYSTEM MOVES TOWARDS OUR AREA...IT WILL SLOW AND
BECOME LESS DEFINED. BOTH THE GFS AND ECMWF HAVE HINTED AT THE
POTENTIAL FOR THIS WAVE TO CUT OFF ACROSS THE SOUTHERN GREAT LAKES.
IF THIS WERE TO OCCUR...UNSETTLED WEATHER COULD PERSIST INTO THE
FIRST PART OF NEXT WEEK...BUT HAVE KEPT THE FORECAST DRY FOR NOW
BEYOND SUNDAY.

INTO NEXT WEEK...BUILDING HEIGHTS ACROSS THE EASTERN HALF OF THE US
WILL LEAD TO WELL ABOVE NORMAL TEMPERATURES IN THE MID 80S FOR A
MAJORITY OF THE WEEK. BUMPED SUPERBLEND HIGHS UP A DEGREE ON MONDAY
AND TUESDAY TO BETTER REFLECT EXPECTED MID 80S TEMPERATURES.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1235 PM EDT TUE AUG 25 2015

UPPER LEVEL AND SURFACE LOW OVER THE GREAT LAKES WILL PERSIST
THROUGH THE FORECAST PERIOD. COLD POOL IS PRONOUNCED AND THIS
FAVORS STRATUS/STRATOCU OVER TERMINALS. LAKE MICHIGAN SURFACE
TEMPERATURES FAVOR ENHANCED BANDING AND ISOLD SHOWERS...ESPECIALLY
NORTH OF THE TERMINALS. STRATUS WILL DISSIPATE AFTER SUNSET - BUT
EXPECT TO REMAIN THROUGH THE FORECAST PERIOD.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...BEACH HAZARDS STATEMENT UNTIL 7 PM CDT THIS EVENING FOR INZ003.

MI...BEACH HAZARDS STATEMENT UNTIL 8 PM EDT THIS EVENING FOR MIZ077.

OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LMZ043-046.

&&

$$

SYNOPSIS...SKIPPER
SHORT TERM...LEWIS
LONG TERM...BENTLEY
AVIATION...LEWIS


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