Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 190542 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 142 AM EDT SUN APR 19 2015 .SYNOPSIS... HIGH PRESSURE OVER THE AREA WILL BEGIN TO PULL EAST AND WASHOUT AS AN UPPER LEVEL LOW OVER THE ROCKIES MOVES EAST. A WARM FRONT WILL THEN LIFT ACROSS THE REGION SUNDAY AFTERNOON FOLLOWED BY A COLD FRONT MONDAY EVENING. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... MID LEVEL RIDGE TO SHIFT EAST OF THE REGION BY MORNING WITH THE FLOW BACKING SRLY AHEAD OF EMBEDDED S/W. FAVORABLE ISENTROPIC LIFT DEVELOPS AHEAD OF THIS S/W BY SUNRISE. BASED ON LATEST TRENDS FROM BOTH SYNOPTIC MODELS AND MESOSCALE MODELS...HAVE SLOWED DOWN PRECIPITATION SLIGHTLY WITH CHC POPS FOR SHOWERS INTO THE SW TOWARD SUNRISE QUICKLY RAMPING UP TO CATEGORICAL SUNDAY MORNING. PREVIOUS FCST IN GOOD SHAPE WITH LOWS RANGING FROM THE UPPER 40S NE TO THE UPPER 50S SW. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/... THE CHANCE OF RAIN SUNDAY WILL BEGIN TO QUICKLY INCREASE AS WAVES OF PVA MOVE FROM THE GULF COAST UP AND AROUND THE BASE OF THE UPPER LEVEL LOW TOWARDS OHIO. HIGH RES MODELS ARE SHOWING A BROAD PRECIP SHIELD AHEAD OF THE WARM SECTOR ARRIVING INTO CINCINNATI AROUND 8 AM AND THEN EXPANDING TO COLUMBUS AROUND 2 PM. PWATS ON THE BOTH THE GFS AND NAM ARE FORECASTED TO REACH 1.65" BY SUNDAY AROUND NOON (NEARING 99TH PERCENTILE FOR THIS TIME OF YEAR). CAPE VALUES SUNDAY WILL BE VERY LOW BUT 0 - 3 KM SRH VALUES ON BOTH THE GFS AND NAM SOUNDINGS ARE VERY IMPRESSIVE. SRH VALUES ARE IN THE 400 TO 600 M2 /S2 RANGE SUNDAY AFTERNOON AS A SURFACE LOW APPROACHES FROM THE SOUTHWEST. AS OF NOW EXPECTING PRECIP SHIELD TO BE MOSTLY WAA DRIVEN INITIALLY WITH STORMS NOT BEING ABLE TO FULLY UTILIZE SUCH HIGH LOW LEVEL SRH VALUES. A WARM FRONT WILL THEN MOVE THROUGH THE AREA SUNDAY AFTERNOON WHICH WILL ALLOW FOR A BRIEF BREAK IN THE PRECIP BEFORE THE REMNANTS OF THE UPPER LEVEL LOW SHEAR OUT AND MOVE OVER THE AREA LATE SUNDAY/ EARLY MONDAY. SUNDAY AFTERNOON AND MONDAY AFTERNOON A FEW THUNDERSTORMS WILL ALSO BE POSSIBLE AS CAPE VALUES COME UP A BIT. THE INITIAL SHORTWAVE THAT DISLODGED THE LOW OVER THE ROCKIES WILL BEGIN TO OCCLUDE AND PUSH A COLD FRONT THROUGH THE AREA MONDAY EVENING. THE GFS AND NAM ARE IN PRETTY GOOD AGREEMENT WITH THE TIMING OF THE FRONT FOR MONDAY EVENING WHILE THE EURO PUSHES THE FRONT THROUGH SLIGHTLY QUICKER. GIVEN THE OCCLUSION PROCESS OF THE LOW ONGOING AT THE TIME HAVE LEANED TOWARDS THE SLOWER FRONTAL PASSAGE. RAIN CHANCES WILL THEN LESSEN TUESDAY AS DRIER AIR MOVES IN FROM THE WEST. IT WILL ALSO BE BREEZY THE NEXT COUPLE OF DAYS AS 850 MB WINDS ARE FORECASTED TO BE CONSISTENTLY AROUND 40 KTS. THIS WILL BE THANKS TO AN ELEVATED PRESSURE GRADIENT THOUGH THE SHORT TERM. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... GOOD AGREEMENT BETWEEN MODELS CONTINUING TO EXHIBIT AN UPPER LOW OVER SOUTHERN ONTARIO DOMINATING THE EARLY/MID EXTENDED PERIOD KEEPING UNSEASONABLY COOL TEMPERATURES AND CONSIDERABLE CLOUDS IN ESPECIALLY THE NORTHERN FCST AREA. THE BEST CHANCE FOR SHOWERS FOR THE ENTIRE FORECAST AREA WILL COME WHEN THE SFC HIGH IN THE SE UNITED STATES MOVES OFFSHORE AND ALLOWS FOR AN ELONGATED COLD FRONT TO SLOWLY PASS THROUGH THE AREA ON WED AND LINGER JUST SOUTH OF THE FCST AREA WED NIGHT. THE UPR LOW FINALLY BEGINS TO PUSH EAST ENOUGH TO LOSE ITS INFLUENCE ON FCST AREA BY FRIDAY NIGHT INTO SATURDAY. SOME MODEL DIFFERENCES THIS FAR OUT IN THE FORECAST IN THAT THE ECMWF IS MORE AMPLIFIED WITH A SOUTHERN STREAM SHORTWAVE...BRINGING IT INTO THE TN AND LOWER OHIO VALLEYS...WHEREAS THE GFS KEEPS IT FURTHER SOUTH OVER THE GULF COAST STATES WHILE CONTINUING TO AMPLIFY THE DEPARTING UPR LOW. HAVE COMPROMISED WITH CHANCE OF PRECIP IN ESPECIALLY THE SOUTHERN THIRD OF FCST AREA. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... ACTIVE WEATHER IS EXPECTED THROUGH THE TAF PERIOD...ALTHOUGH VFR CONDITIONS ARE EXPECTED FOR THE FIRST 6-12 HOURS. AN AREA OF RAIN IS EXPECTED TO DEVELOP AND MOVE NORTH INTO THE TAF SITES BETWEEN 11Z AND 15Z...THOUGH CONDITIONS MAY INITIALLY BE VFR AS THE RAIN BEGINS. HOWEVER...LOW-LEVEL MOISTURE WILL THICKEN OVER TIME...LEADING TO MVFR CEILINGS AND VISIBILITIES. DURING THE AFTERNOON...THERE IS A CHANCE THAT SOME IFR CEILINGS MAY DEVELOP...AND HEAVIER RAIN SHOWERS COULD ALSO PRODUCE BRIEF IFR VISIBILITIES. ALTHOUGH RAIN WILL BECOME A LITTLE MORE SCATTERED BY LATE AFTERNOON...THERE DOES APPEAR TO BE A SLIGHT CHANCE OF THUNDER...THOUGH NOT YET CLEAR ENOUGH IN TIMING OR PLACEMENT TO INCLUDE IN THE TAFS. RAIN WILL BECOME MUCH MORE SCATTERED GOING INTO THE OVERNIGHT HOURS...BUT WITH ENOUGH SHOWERS AROUND TO KEEP A VCSH IN THE TAFS. CEILINGS MAY IMPROVE SLIGHTLY GOING INTO THE NIGHT...BUT THIS IS ALSO NOT TOTALLY CERTAIN. THE OTHER ISSUE TO HANDLE IS THE WINDS...WHICH WILL INCREASE IN STRENGTH DURING THE MORNING HOURS. BY AFTERNOON...SUSTAINED WINDS WILL BE AS HIGH AS 20 KNOTS...WITH GUSTS THAT MAY APPROACH 30 KNOTS AT TIMES. WINDS WILL SUBSIDE SLIGHTLY DURING THE LATE EVENING AND INTO THE OVERNIGHT HOURS. IN TERMS OF DIRECTION...WINDS SHOULD MAKE A GRADUAL CLOCKWISE TURN THROUGH THE TAF PERIOD...BEGINNING WITH AN ENE DIRECTION AND ENDING FROM THE SSW. OUTLOOK...MVFR/IFR CEILINGS AND VISIBILITIES ARE POSSIBLE MONDAY...WITH A CHANCE OF THUNDERSTORMS. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HAINES NEAR TERM...AR SHORT TERM...HAINES LONG TERM...JDR AVIATION...HATZOS

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