Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 210017 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 817 PM EDT SUN APR 20 2014 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO EXTEND ACROSS THE REGION TODAY...BEFORE MOVING OFF TO THE EAST TONIGHT. A COLD FRONT WILL MOVE THROUGH THE AREA LATE MONDAY NIGHT INTO TUESDAY MORNING...BRINGING RAIN TO THE AREA. ANOTHER AREA OF HIGH PRESSURE WILL BUILD IN FOR THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... SURFACE HIGH PRESSURE IS CENTERED OVER NEW ENGLAND...AND WILL MOVE OFF THE EAST COAST TONIGHT. THIS HIGH EXTENDS INTO THE OHIO VALLEY AND EVEN AS FAR SOUTH AS THE NORTH-CENTRAL GULF COAST...WITH VERY DRY CONDITIONS IN PLACE. THIS IS ALLOWING FOR LARGE DIURNAL SWINGS...AS TEMPERATURES HAVE REACHED THE MID 70S ACROSS THE ILN CWA (WITH SOME AREAS EVEN GETTING INTO THE UPPER 70S). THE MIXED BOUNDARY LAYER HAS ALLOWED FOR SOME SWINGS IN THE WINDS...WITH LIGHT AND VARIABLE CONDITIONS INTERSPERSED WITH BRIEF GUSTY PERIODS OUT OF THE SOUTHEAST. THOUGH A FEW PATCHES OF CIRRUS MAY CONTINUE TO MOVE THROUGH THE AREA TONIGHT...RADIATIONAL COOLING WILL BE FAIRLY EFFECTIVE. WITH A WARMER STARTING POINT AND LIGHT SOUTHERLY FLOW...TEMPERATURES WILL CERTAINLY BE WARMER THAN THIS MORNING...THOUGH THE FAR EASTERN CWA AND OTHER OUTLYING LOCATIONS WILL STILL BE CAPABLE OF DROPPING INTO THE MID TO UPPER 40S. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... ON MONDAY...THE ILN CWA WILL REMAIN OUT AHEAD OF A DEVELOPING COLD FRONT...IN A REGIME OF SOUTHWEST WIND FLOW. CLOUDS WILL GRADUALLY BEGIN INCREASING DURING THE DAY...WITH ENOUGH MOISTURE BUILDING IN TO SUPPORT CUMULUS AS WELL AS HIGHER CLOUDS. HOWEVER...IT DOES NOT APPEAR THAT THESE CLOUDS WILL HAVE A SUBSTANTIAL IMPACT ON TEMPERATURES...WITH THE CHANGE IN FLOW SUPPORTING VALUES A FEW DEGREES HIGHER THAN SUNDAY. THE BOUNDARY LAYER WILL BE WELL-MIXED AGAIN...SO A FEW GUSTS TO AROUND 15-20 KNOTS WILL BE POSSIBLE. WEAK INSTABILITY WILL BEGIN TO DEVELOP NEAR THE PEAK HEATING OF THE DAY...AND THE SPC WRF-NMM IS NOW CLOSE ENOUGH IN RANGE TO DEPICT SOME WIDELY SCATTERED CONVECTION OVER THE WESTERN HALF OF THE ILN FORECAST AREA BY LATE AFTERNOON (EVEN THOUGH THE MAIN FRONTAL FORCING WILL NOT YET HAVE ARRIVED). SLIGHT CHANCE POPS WERE EXTENDED INTO THE AREA A LITTLE EARLIER THAN WITH THE PREVIOUS FORECAST...THOUGH MOST LOCATIONS WILL REMAIN DRY. BY MONDAY EVENING...THE FRONT WILL BEGIN ITS APPROACH...BUT MOST OF THE FORECAST PRECIPITATION EXISTS WELL AHEAD OF IT (MORE CLOSELY ALIGNED WITH FORCING SLIGHTLY ALOFT). PERHAPS BECAUSE OF THE LACK OF FORCING DEFINITION IN THE LOW-LEVELS...AND A MOISTURE FEED OF QUESTIONABLE QUALITY...IT IS NOT SURPRISING THAT QPF DEPICTIONS FOR THIS MINOR EVENT ARE SPOTTY AND PATCHY (AND NOT AT ALL CONSISTENT FROM MODEL TO MODEL). THOUGH RAIN IS LIKELY TO AFFECT THE ENTIRE CWA AT SOME POINT IN A 12-TO-18 HOUR PERIOD...THESE TIMING AND PLACEMENT CONCERNS PRECLUDE THE INCLUSION OF CATEGORICAL POPS FOR THIS FORECAST CYCLE. PRECIPITATION FORECASTS ARE GENERALLY AROUND A QUARTER INCH OR LESS...AND WITH ONLY WEAK INSTABILITY...NO HWO-WORTHY HAZARDS ARE EXPECTED EARLY THIS WEEK (THOUGH SOME THUNDER IS POSSIBLE IN THE WEAK INSTABILITY). MODELS DO GENERALLY HAVE A GOOD TIMING AGREEMENT ON THE DEPARTURE OF THE MOISTURE AS THE FRONT PASSES...WITH THE CWA APPEARING TO BE COMPLETELY DRY BY 18Z. THE CHANGING AIR MASS WILL LEAD TO COOLER CONDITIONS ON TUESDAY...THOUGH SOME RECOVERY IN THE SUN WILL BE POSSIBLE AS SKIES CLEAR BEHIND THE FRONT. HOWEVER...PERSISTENT COLD ADVECTION ON NNW FLOW WILL ALLOW FOR TEMPERATURES TO DROP INTO THE 30S ON TUESDAY NIGHT...WITH MID 30S POSSIBLE IN THE NORTHERN AND NORTHWESTERN CWA. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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HAVE LEANED MORE WITH WPC/S ADVICE WHICH IS TO USE A BLEND OF THEIR GUIDANCE...THE LATEST GFS AND DISCOUNT THE 00Z ECMWF AND THE 12Z ECMWF FOR THE FORECAST INTO THE WEEKEND/EARLY NEXT WEEK WHICH PUSHES A MORE ENERGETIC SFC CYCLONE THROUGH THE CNTRL PLAINS AND INTO THE OHIO VALLEY. ON WEDNESDAY...SURFACE HIGH PRESSURE WILL BE PUSHING EAST ACROSS THE GREAT LAKES AND OHIO VALLEY. IT WILL BE COOLER WITH HIGHS RANGING FROM THE UPPER 50S NORTH TO THE LOWER 60S ALONG AND SOUTH OF THE OHIO RIVER. FOR WEDNESDAY NIGHT INTO THURSDAY NIGHT...NEXT COLD FRONT TO AFFECT OUR REGION IS STILL POISED TO ARRIVE THURSDAY NIGHT. TIMING KEEPS CHANGING SOME IN TERMS OF PCPN ARRIVAL FROM RUN TO RUN. THERE LOOKS LIKE ENOUGH DYNAMICS...MOISTURE AND INSTABILITY TO GO WITH LIKELY POPS ACRS OUR AREA THURSDAY NIGHT. BEFORE HAND...PCPN WILL ARRIVE IN THE FAR WRN ZONES LATE IN THE DAY ON THURSDAY. WAA AHEAD OF THE FRONT WILL PUSH HIGHS INTO THE UPPER 60S AND MID 70S ON THURSDAY. ON FRIDAY...FRONT WILL MOVE EAST...AND IT LOOKS LIKE WE WILL DRY OUT. CAA WILL BE BEGINNING ON FRIDAY BUT WILL BE DELAYED SOME. SO...UNDER PARTLY CLOUDY SKIES...HIGHS WILL RANGE FROM THE UPPER 60S NW TO THE MID 70S FAR SOUTHEAST. FOR FRIDAY NIGHT INTO SATURDAY NIGHT...A QUITE LARGE UPR LVL CLOSED LOW WILL TRAVERSE THE GREAT LAKES REGION. AT THIS TIME...IT LOOKS LIKE ANY PCPN WILL REMAIN NEAR THE LAKES THEMSELVES. SO...SKIES SHOULD BE PARTLY CLOUDY WITH A COOLING TREND EXPECTED INTO THE WEEKEND AS HIGHS DROP TO BELOW NORMAL READINGS FOR LATE APRIL. ON SUNDAY...SURFACE HIGH PRESSURE IS FORECAST TO PUSH THROUGH THE REGION BEHIND DEPARTING UPR LVL CLOSED LOW. HIGHS WILL REMAIN COOL FOR LATE APRIL.
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&& .AVIATION /00Z MONDAY THROUGH FRIDAY/...
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AREA OF BROKEN CI WILL AFFECT THE TAFS FOR THE FIRST COUPLE OF HOURS OF THE TAFS...THEN SCT CONDITIONS ARE EXPECTED TO TAKE OVER UNTIL ABOUT 06Z. ADDITIONAL CI WILL WORK BACK INTO THE TAFS AHEAD OF AN EJECTING H5 S/W. CIGS WILL LOWER SOME AFT 12Z AS AC DECK WORKS IN. LOW LEVEL MOISTURE WILL BE SLOW TO POOL AHEAD OF ADVANCING CDFNT...SO ANY CU THAT DEVELOPS TOMORROW UNDER THE AC SHOULD BE SCT. CONSENSUS OF LATEST MODEL RUNS KEEP PCPN W OF THE TAFS THRU 00Z. AT CVG IN THE 30 HOUR PORTION BROUGHT MVFR PREVAIL SHOWERS IN AROUND 03Z. MENTIONED A VCTS AS SFC BASED INSTABILITY WILL BE WAINING BY THAT TIME...BUT MODELS ARE SHOWING A LITTLE ELEVATED INSTABILITY. OUTLOOK...MVFR CEILINGS AND VISIBILITIES ARE POSSIBLE MONDAY NIGHT INTO TUESDAY.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...HICKMAN AVIATION...SITES

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