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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 211756
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
156 PM EDT TUE MAY 21 2013

.SYNOPSIS...
A WARM AND HUMID AIR MASS WILL REMAIN IN PLACE THROUGH WEDNESDAY.
OCCASIONAL PERIODS OF SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE.
A COLD FRONT WILL MOVE THROUGH THE REGION ON THURSDAY...BEFORE
COOLER AIR SETTLES IN ON FRIDAY AND INTO THE WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
-- Changed Discussion --
SATELLITE IMAGERY SUGGESTS THAT MCV IS TRACKING ALONG LAKE ERIE.
SUBSIDENCE IN THE WAKE OF THIS HAS LEFT LITTLE IF ANY LOW LEVEL
CLOUDS AND NO PRECIPITATION. IT IS NOT CLEAR IF/HOW MUCH THE REGION
CAN RECOVER BEFORE DIURNAL HEATING ABATES.

BEST CHANCE OF STORMS STILL APPEARS TO BE FOR THE SOUTHEAST
COUNTIES. INSTABILITY IS THE HIGHEST THERE AND SHOULD REMAIN SO
THROUGH THE REMAINDER OF THE DAY. CONVECTIVE SYSTEM MOVING OUT OF
WESTERN KENTUCKY HAS THE POTENTIAL TO DEVELOP FURTHER NORTH WHICH
WOULD INDICATE THE GREATEST THREAT WILL BE IN NORTHEASTERN
KENTUCKY AND SOUTH CENTRAL OHIO. HOWEVER CANNOT COMPLETELY RULE
OUT A FEW STORMS ELSEWHERE ESPECIALLY ALONG AND SOUTH OF I-71.

HAVE ONLY MADE SOME SLIGHT ADJUSTMENTS TO TEMPERATURES BASED ON
LATEST OBSERVATIONS/SHORT TERM GUIDANCE TRENDS.
-- End Changed Discussion --

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
CONVECTION WILL LIKELY BE ONGOING FOR AT LEAST PART OF THE
FORECAST AREA DURING THE TUESDAY EVENING HOURS...WITH A DIURNAL
MIN LEADING TO MORE TRANQUIL CONDITIONS OVERNIGHT. HOWEVER...BY
WEDNESDAY MORNING...THIS MAY BEGIN TO CHANGE AGAIN. A SHORTWAVE
MOVING OUT OF THE SOUTHERN PLAINS WILL EVENTUALLY MAKE ITS WAY
JUST EAST OF THE ILN CWA BY MORNING...WITH MODEL AGREEMENT ON AN
ASSOCIATED CONVECTIVE COMPLEX SPREADING INTO INDIANA BY THEN.
MEANWHILE...SURFACE LOW PRESSURE WILL STRENGTHEN AS IT MOVES
THROUGH ILLINOIS AND INTO MICHIGAN...WITH GENERAL SURFACE
TROUGHING AND HEIGHT FALLS ALOFT SPREADING INTO THE ILN CWA. THIS
IS A FAVORABLE ENVIRONMENT FOR LIFT...AND SHOULD SUPPORT A LIKELY POP
FORECAST THROUGH MOST OF THE DAY WEDNESDAY. ALTHOUGH GENERALLY
UNIDIRECTIONAL...THE INCREASING PRESSURE GRADIENT AND
JUXTAPOSITION WITH THE RIGHT ENTRANCE REGION OF THE UPPER JET WILL
ALSO SUPPORT AN INCREASED BIT OF SHEAR AND FORCING (RESPECTIVELY).
THE LIMITING FACTOR FOR SEVERE POTENTIAL WILL BE
INSTABILITY...WHICH DOES NOT APPEAR TO BE PARTICULARLY STRONG (AND
THIS IS NOT SURPRISING GIVEN THE LACK OF EXPECTED SURFACE
HEATING). TEMPS ALOFT WILL CONTINUE TO DROP...WHICH SHOULD HELP
GENERATE 500-1000 J/KG IF SOME SUN CAN BE REALIZED. AN ALTERNATE
POSSIBILITY WOULD KEEP PRECIPITATION OVER THE CWA THROUGH THE
MORNING AND EARLY AFTERNOON...ESSENTIALLY LIMITING DESTABILIZATION
TO NEAR-ZERO. THE SOUNDINGS LOOK RATHER MOIST...LEADING TO THIN
CAPE AND LOW LCLS.

THE LARGE NORTHERN PLAINS UPPER LOW WILL FINALLY BE ON THE MOVE
BY LATE WEDNESDAY...CROSSING THE ILN CWA ON THURSDAY. THIS WILL
BRING ANOTHER HIGH CHANCE OF POPS ON THURSDAY...MAINLY IN THE
NORTH AND GENERALLY WITH DIURNAL TIMING. BEHIND THE AXIS OF THIS
TROUGH...RAPID DRYING IS EXPECTED.

TEMPERATURES WILL BEGIN A DOWNWARD TREND AFTER THE POORLY-DEFINED
COLD FRONT (ASSOCIATED WITH THE WEDNESDAY SURFACE LOW) MOVES
THROUGH THE REGION. A STRONGER CHANGE IN NEAR-SURFACE AIR MASS IS
EXPECTED BEHIND THE TROUGH ON THURSDAY NIGHT...WITH NORTHERLY
WINDS ADVECTING COLDER AND DRIER AIR INTO THE REGION.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
SURFACE HIGH PRESSURE WILL BUILD DOWN FROM THE NORTH AND INTO OUR
AREA FRIDAY INTO SATURDAY...KEEPING A SEASONABLY COOL AIRMASS IN
PLACE THROUGH THE START OF THE WEEKEND. HIGHS ON FRIDAY WILL BE IN
THE MID TO UPPER 60S AND WITH THE SURFACE HIGH OVERHEAD...LOWS
SATURDAY MORNING WILL DIP INTO THE LOW TO MID 40S. THE SURFACE
HIGH WILL BEGIN TO SHIFT OFF TO THE EAST THROUGH THE REMAINDER OF
THE WEEKEND AS MID LEVEL RIDGING BEGINS TO ESTABLISH ITSELF ALOFT.
THIS WILL RESULT IN A GRADUAL RETURN TO WARMER TEMPERATURES
THROUGH THE REST OF THE HOLIDAY WEEKEND. MODELS ARE STILL TRYING
TO SUGGEST THE POSSIBILITY OF SOME ENERGY DROPPING DOWN FROM THE
NORTHWEST LATE IN THE WEEKEND. HOWEVER...TIMING AND PLACEMENT ARE
HIGHLY VARIABLE SO WILL MAINTAIN A DRY FORECAST AT THIS POINT.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
CHANCE OF THUNDERSTORMS WILL BE THE MAIN AVIATION ISSUE THROUGH
THE TAF PERIOD. SHORT TERM TRENDS SUGGEST THAT THE POSSIBILITY OF
CONVECTION FOR THIS AFTERNOON AND EVENING IS DECREASING AT MOST OF
THE TERMINALS. BEST CHANCE APPEARS TO BE IN THE CINCINNATI AREA
AND EVEN THERE CONFIDENCE IS ONLY HIGH ENOUGH TO KEEP VCTS IN THE
TAFS. ELSEWHERE WILL HAVE TO CONTINUE TO MONITOR CONDITIONS BUT
PROBABILITY IS TOO LOW TO INCLUDE IN THE FORECAST.

GUSTY SOUTH SOUTHWEST WINDS WILL DIMINISH AFTER 00Z AND BACK
SOMEWHAT. EXPECT HIGH CLOUDS TO SPREAD OVER THE REGION. BUT IF
THESE ARE NOT TOO THICK THEN THERE IS THE POSSIBILITY OF SOME
LIGHT FOG AT KLUK.

WINDS WILL PICK UP AGAIN ON WEDNESDAY. THERE IS A CHANCE OF SHOWERS
AND THUNDERSTORMS PRETTY MUCH ANY TIME AFTER 12Z BUT THE HIGHER
PROBABILITY WILL BE VERY LATE IN THE TAF PERIOD.

OUTLOOK...THUNDERSTORMS LIKELY WEDNESDAY AFTERNOON AND EVENING.
MVFR TO IFR CEILINGS POSSIBLE LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING. MVFR CEILINGS POSSIBLE AGAIN THURSDAY NIGHT.
-- End Changed Discussion --

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.

&&

$$
SYNOPSIS...HATZOS
NEAR TERM...
SHORT TERM...HATZOS
LONG TERM...JGL
AVIATION...