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000
FXUS63 KIWX 141944
AFDIWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
344 PM EDT TUE MAY 14 2013

.SYNOPSIS...
ISSUED AT 1058 AM EDT TUE MAY 14 2013

A STRONG WARM FRONT WILL TRACK ACROSS THE SOUTHERN GREAT LAKES AND
OHIO VALLEY TODAY ALLOWING FOR MUCH WARMER CONDITIONS TODAY AND
WEDNESDAY. AN UPPER LEVEL DISTURBANCE TRACKING OUT OF THE PACIFIC
NORTHWEST WILL MOVE INTO ONTARIO TONIGHT. A COLD FRONT TRAILING
SOUTH FROM THIS DISTURBANCE WILL DROP INTO THE REGION ON WEDNESDAY
PROVIDING A CHANCE OF SHOWERS AND THUNDERSTORMS WEDNESDAY
AFTERNOON THROUGH THURSDAY.

&&

.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 343 PM EDT TUE MAY 14 2013


THE MAIN CHALLENGES THIS PERIOD ARE CHANCES AND LOCATIONS FOR ANY
THUNDERSTORMS TONIGHT AND WEDNESDAY AFTERNOON. A VERY STRONG WARM
FRONT WAS LIFTING NORTH ACROSS THE AREA THIS AFTERNOON. THE PRESSURE
GRADIENT WILL TIGHTEN OVER THE AREA OVERNIGHT...PREVENTING WINDS
FROM DECOUPLING MUCH. FAVORED THE WARMER MET TEMPS IN THIS
REGARD...GIVEN THIS UNUSUAL VERY WARM PATTERN INCLUDING TUESDAY
AFTERNOON HIGHS JUST UPSTREAM IN THE 90S...AND TOPPING 100 DEGREES
FURTHER WEST. AN IMPRESSIVE AXIS OF THETA E ALONG THE FRONT WITH
VALUES OF 337K AT 850 MB WILL SURGE SOUTHEAST OVERNIGHT. REALLY A
HARD CALL ABOUT INTRODUCING CONVECTION OVERNIGHT...BUT BELIEVE MID
LEVEL CAPPING AND ESPECIALLY A DRY LOWER ENVIRONMENT WILL INHIBIT
CONVECTION. THE NAM/WRF WAS SHOWING TOO MUCH MOISTURE IN THE LOW
LEVELS...SO FOR NOW LEFT THE FORECAST FOR TONIGHT DRY. AS FOR
WEDNESDAY...LOWERED THUNDERSTORM CHANCES OVER MOST AREAS. AGAIN...
BELIEVE MID LEVEL CAPPING AND DRY CONDITIONS IN THE LOW LEVELS WILL
INHIBIT CONVECTION.


&&

.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 343 PM EDT TUE MAY 14 2013

FORECAST PERIOD TO BEGIN WITH STALLED FRONTAL BOUNDARY OVER THE
REGION WITH LATEST MODEL GUIDANCE TRENDING FURTHER SOUTH SUGGESTING
GREATER POTENTIAL FOR DRY FCST WED NIGHT OVER MUCH OF THE FORECAST
AREA...HAVE CONTINUED DOWNWARD TREND IN POPS FOR THIS PERIOD
ACCORDINGLY. SOUTHERN STREAM SHORTWAVE WILL BE MOVING ACROSS THE TN
VALLEY ON THURSDAY WITH MODELS OFFERING VARYING SOLNS ON RESULTING
POSITION OF SFC FRONT...SO LEANING TOWARD NO CHANGES TO THIS PERIOD
AND STAYING WITH DRY FCST FOR ALL BUT EXTREME SOUTHERN PORTION OF
THE CWA. UPSTREAM PATTERN THEN BEGINS TO AMPLIFY ON FRIDAY AS UPPER
TROF DIGS INTO THE WEST COAST. RIDGING IN THE PLAINS IN RESPONSE TO
THIS ALONG WITH WEAK SHORTWAVE COMING OUT OF THE MID MS VALLEY WILL
BRING NORTHWARD MOVEMENT TO SFC FRONT AND INCREASING PRECIP CHANCES
GOING INTO THE WKND. UPPER TROF EJECTS OUT OF THE FOUR CORNERS ON
SAT INDUCING LEE SIDE CYCLOGENESIS IN THE WESTERN PLAINS AND ALSO
SHIFTING UPPER RIDGE AXIS OVER OUR AREA. END RESULT MAY BE A CAPPED
WARM SECTOR OVER US AND A DRY DAY FOR SUNDAY. PLENTY OF UNCERTAINTY
REMAINS WITH THIS SCENARIO PLAYING OUT SO STILL MAY NEED TO CARRY A
SMALL CHANCE POP ATTM. LOW CONFIDENCE PATTERN BEING OFFERED TOWARD
THE END OF THE FCST PERIOD WITH A VERTICALLY STACKED AND CLOSED
SYSTEM SOMEWHERE IN THE WESTERN GREAT LAKES/NORTHERN PLAINS. THIS
PATTERN WOULD LEND ITSELF TOWARD SOME TYPE OF PRE-FRONTAL TROF
AND/OR SHORT WAVE EJECTING OUT OF THE CLOSED LOW PRIOR TO THE
ARRIVAL OF THE PRIMARY FRONT AND THEREFORE FAVORING A CONTINUED
CHANCE OF SH/TSRA THROUGH DAY 7. TEMPS ON AVERAGE EXPECTED TO BE
5-10F ABOVE NORMAL THROUGH THE EXTENDED PERIOD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 343 PM EDT TUE MAY 14 2013


VERY STRONG WARM AIR ADVECTION WAS OVER THE AREA...ACCOMPANIED BY
GUSTY WINDS GIVEN THE TIGHT PRESSURE GRADIENT. WINDS SHOULD PERSIST
OUT OF THE SW AHEAD OF A COLD FRONT...ALTHOUGH SPEEDS SHOULD
DIMINISH A LITTLE BY LATE AFTERNOON. KEPT SHOWERS/STORMS OUT OF THE
TAFS. ALTHOUGH A FRONT WILL BE MOVING INTO THE AREA...THE ATMOSPHERE
BE A WARM/CAPPED ENVIRONMENT IN THE LOW LEVELS WITH LIMITED MOISTURE.

&&

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

$$

SYNOPSIS...NG
SHORT TERM...SKIPPER
LONG TERM...JAL
AVIATION...SKIPPER


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