Area Forecast Discussion
Issued by NWS Northern Indiana

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000
FXUS63 KIWX 311509
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1109 AM EDT THU JUL 31 2014

.SYNOPSIS...
ISSUED AT 405 AM EDT THU JUL 31 2014

A SERIES OF WEAK DISTURBANCES ROTATING AROUND AN UPPER LEVEL LOW
WILL PROVIDE A LOW CHANCE OF MAINLY AFTERNOON SHOWERS AND ISOLATED
THUNDERSTORMS THROUGH SATURDAY. HIGHS EACH DAY ARE FORECAST TO
REACH TO NEAR 80 DEGREES...WITH LOWS GENERALLY NEAR 60.

&&

.UPDATE...
ISSUED AT 1110 AM EDT THU JUL 31 2014

UPDATE SENT EARLIER TO FRESHEN UP GRIDS WITH MUCH LESS CLOUD COVER
THIS MORNING AND A GREATER INCREASE IN DEWPOINTS.

OUTSIDE OF A FEW CLOUDS IN FAR NW AND SW AREAS CLEAR SKIES BEING
ENJOYED WITH TEMPS RESPONDING NICELY, ALREADY CLIMBING INTO THE
UPPER 60S TO LOWER 70S. HIGHS STILL LOOK ON TRACK IN THE UPPER 70S
AT THIS POINT BUT WITH THE WARMER START MAY NEED TO TWEAK THINGS
IN A FEW SPOTS.

HIGH RES MODELS CONTINUE TO SUGGEST WIDELY SCATTERED
SHOWERS/ISOLATED STORMS AFTER 18Z AS PEAK HEATING IS REACHED.
COVERAGE SHOULD BE KEPT IN CHECK WITH LACK OF STRONG TRIGGERS.
HOWEVER MORE IN THE WAY OF MOISTURE AVAILABLE WHICH MAY BRING
BRIEF HEAVY RAIN WITH ANY OF THE STRONGER CELLS.

&&

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM EDT THU JUL 31 2014

MID LEVEL HEIGHT RISES WITH STRONGER/MORE PERTURBED NORTHWEST FLOW
(AND CORE OF COLD AIR ALOFT) SHIFTING ENE OF THE LOCAL AREA WILL
RESULT IN LOWER COVERAGE/PROBABILITY OF DIURNALLY DRIVEN
SHOWERS/THUNDER AND SLIGHTLY WARMER TEMPS WHEN COMPARED TO THE
PREVIOUS TWO DAYS. SUBTLE LOW LEVEL MOISTURE ADVECTION AS WINDS
INCREASE/BACK WESTERLY UNDER LINGERING TROUGH AXIS SHOULD STILL
SUPPORT 500-800 J/KG OF THIN CAPE BY THIS AFTN. THIS AND LACKING
CONVECTIVE INHIBITION MAY BE ENOUGH TO HELP GENERATE ISOLATED
SHOWERS/THUNDER ALONG A WEAK SFC CONVERGENCE AXIS THAT WILL LIKELY
MATERIALIZE DOWNWIND OF LAKE MI. REGARDLESS...ANOTHER MAINLY
DRY/PLEASANT DAY FOR LATE JULY STANDARDS.

LOSS OF HEATING AND LACKING SUPPORT ALOFT WILL LIKELY RESULT IN A
DRY EVENING. THE MID LEVEL FLOW WILL BACK MORE SOUTHWESTERLY BY
LATER TONIGHT IN ADVANCE OF SHORTWAVE ENERGY THAT WILL APPROACH ON
THE BACKSIDE OF THE PRIMARY EASTERN CONUS UPPER TROUGH. MODEST
MOISTURE TRANSPORT WITH THIS FEATURE COULD AID IN BRINGING A FEW
SHOWERS TO NW IN/SW LOWER MI.

&&

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 405 AM EDT THU JUL 31 2014

AN UPPER LOW WILL BE NEAR JAMES BAY AT THE START OF THE PERIOD AND
SHOULD BE LIFTING NORTHEAST. THIS WILL ALLOW THE UPPER AIR PATTERN
TO BECOME MORE HIGH ZONAL...WITH SHORT WAVE ENERGY MOVING SOUTHEAST
TOWARD THE WESTERN GREAT LAKES REGION. KEPT A CHANCE FOR MAINLY
AFTERNOON THUNDERSTORMS FRIDAY AND SATURDAY GIVEN LIMITED LOW LEVEL
CONVERGENCE...BUT WITH SUFFICIENT DAYTIME HEATING TO ALLOW AFTERNOON
CAPE VALUES TO ARISE TO BETWEEN 500 AND 1000 J/KG. MOISTURE FLUX
INTO THE AREA WILL REMAIN VERY LIMITED UNTIL NEAR THE END OF THE
FORECAST PERIOD. GIVEN THE VERY LOW CORRELATION COEFFICIENT OF THE
500 MB ANALOGS...AND LIMITED RUN TO RUN CONSISTENCY...KEPT THE
ONGOING CHANCE FOR THUNDERSTORMS TUESDAY AND WEDNESDAY. AS FOR
TEMPERATURES...850 MB TEMPERATURES SHOULD GRADUALLY RECOVER...AND
ALLOW HIGHS TO TOP 80 DEGREES. FAVORED THE COOLER GFS MEX MEAN
ENSEMBLE NUMBERS OVER THE WARMER OPERATIONAL RUN FORECAST
TEMPERATURES.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 613 AM EDT THU JUL 31 2014

LIGHT WINDS/MOSTLY CLEAR SKIES HAS ALLOWED TEMPS TO DROP BELOW
XOVER VALUES EARLY THIS MORNING WITH IFR-MVFR VIS RESTRICTIONS
COMMON ACROSS NORTHERN INDIANA. EXPECT THIS TO BURN OFF SHORTLY
AFTER TAF ISSUANCE LEAVING VFR CONDITIONS FOR THE REST OF THE
PERIOD. WEAK DIURNAL DESTABILIZATION MAY ONCE AGAIN ALLOW A FEW
AFTN SHOWERS TO DEVELOP...ALTHOUGH COVERAGE/PROBABILITY APPEARS
LOWER THAN PREVIOUS DAYS GIVEN BUILDING MID LEVEL HEIGHTS/WARMING
ALOFT WITH LOW LEVEL TROUGH FOCUSED WELL NORTH ACROSS THE NRN
GREAT LAKES. OPTED TO HOLD ON TO A DRY FCST AT FWA/SBN AS A
RESULT.


&&

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

$$

UPDATE...FISHER
SYNOPSIS...MARSILI/STEINWEDEL
SHORT TERM...STEINWEDEL
LONG TERM...SKIPPER
AVIATION...STEINWEDEL


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