Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 211044 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 644 AM EDT TUE APR 21 2015 .SYNOPSIS... A STRONG LOW PRESSURE SYSTEM OVER THE GREAT LAKES WILL BRING VERY WINDY CONDITIONS TODAY...ALONG WITH A CHANCE OF SHOWERS AT TIMES THROUGH WEDNESDAY MORNING. DRIER CONDITIONS ARE EXPECTED FROM WEDNESDAY AFTERNOON THROUGH THE REST OF THE WEEK...WITH BREEZY AFTERNOONS AND COOL TEMPERATURES. ANOTHER CHANCE OF RAIN WILL ARRIVE ON SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... SCATTERED TO BROKEN CLOUDS IN THE 6KFT-10KFT LAYER ARE CROSSING THE ILN CWA FROM WEST TO EAST...DELINEATED VERY NICELY ON IR SATELLITE. WITHIN THESE PATCHES OF CLOUDS ARE SOME CONVECTIVE-LOOKING SHOWERS...AND ALTHOUGH NO LIGHTNING HAS BEEN OBSERVED...PEA SIZE HAIL WAS OBSERVED WITH ONE OF THE SHOWERS (THANKS TO THE FREEZING LEVELS OF AROUND 4KFT). THE PRIMARY CONCERN TODAY REMAINS THE THREAT FOR STRONG WINDS...AND AN ANALYSIS OF 00Z MODEL DATA SUPPORTED MAINTAINING THE CURRENT ORIENTATION FOR THE WIND ADVISORY (WITH A SPECIAL WEATHER STATEMENT FOR THE REST OF THE FORECAST AREA). STRONG UNIDIRECTIONAL FLOW (AT ABOUT 250 DEGREES) EXTENDS THROUGH THE ENTIRE DEPTH OF THE TROPOSPHERE...WITH VALUES STEADILY INCREASING OFF THE SURFACE. USING A RECENT RAP RUN AT KDAY ON BUFKIT AS AN EXAMPLE (AT 18Z)...WINDS INCREASE TO 40 KNOTS AT 825MB...THEN 50 KNOTS AT 700MB...AND 60 KNOTS AT 600MB. TODAY WILL BE AN EXERCISE IN MIXING...AS THE EVENTUAL DEPTH OF THE MIXED LAYER WILL LIKELY DETERMINE JUST HOW STRONG THE WINDS GET. GUSTS IN THIS FORECAST WERE GENERALLY GLEANED FROM BUFKIT MOMENTUM TRANSFER VIA RAP/GFS FORECASTS...WITH VALUES IN THE LOWER 40 KNOT RANGE IN THE NORTHERN CWA...AND LOWER 30 KNOT RANGE IN THE SOUTHERN CWA. ALTHOUGH CLEAR SKIES WILL BE IN PLACE AT THE BEGINNING OF THE DAY...WEAK ELEVATED FORCING AND A SLIGHT INCREASE IN MOISTURE AT THE TOP OF THE (RATHER HIGH) MIXED LAYER WILL RESULT IN SOME CLOUD DEVELOPMENT...AND EVENTUALLY SHOWERS IN THE SOUTHEASTERN HALF OF THE FORECAST AREA. THESE SHOWERS MAY BE VERY HIGH-BASED (PERHAPS 8000 FEET)...WITH SCATTERED COVERAGE AT MOST. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... PRECIPITATION IS EXPECTED TO MOVE INTO THE REGION (OR PERHAPS DEVELOP OVER THE FORECAST AREA) ON TUESDAY NIGHT INTO WEDNESDAY MORNING. ALTHOUGH THERE ARE SOME MODEL DIFFERENCES WITH REGARDS TO THE INTENSITY AND LAYOUT OF THE PRECIPITATION...THE OVERALL TIMING APPEARS TO FAVOR THE 06Z-15Z TIME FRAME FOR THE ILN FORECAST AREA...AHEAD OF A SHORTWAVE AND A SURFACE COLD FRONT. ALTHOUGH THIS FRONT SHOWS UP NICELY ON MSLP PLOTS...THE WIND SHIFT AND CHANGE IN AIR MASS ARE NOT ESPECIALLY NOTABLE. INSTABILITY (EVEN ELEVATED) WILL BE HARD TO COME BY...SO THOUGH THUNDER IS NOT AN IMPOSSIBILITY WITH THIS SETUP...THE CHANCE SEEMS VERY LOW. ONCE THIS FRONT PASSES...VERY SIMILAR CONDITIONS ARE EXPECTED FOR THE REST OF THE WEEK...WITH NORTHWEST FLOW AND COOL WEATHER. OHIO IS LIKELY TO REMAIN IN BETWEEN AREAS OF ENHANCED MOISTURE FROM THE NORTHERN AND SOUTHERN STREAMS...LEADING TO GENERALLY SUNNY CONDITIONS UNTIL FRIDAY NIGHT. TEMPERATURES ON THURSDAY AND FRIDAY MORNING MAY BE COOL ENOUGH FOR FROST...BUT MOISTURE AND WIND FORECASTS ARE NOT AS FAVORABLE. THUS...FROST WILL NOT BE INCLUDED IN THE GRIDS OR HWO. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... SOME DEEPER MOISTURE WILL BE PULLED UP TOWARD OUR AREA ON SATURDAY AHEAD OF SHORT WAVE ENERGY MOVING OUT OF THE ROCKIES. WHILE THE BEST FORCING/MOISTURE ASSOCIATED WITH THIS WILL REMAIN TO OUR SOUTH...SOME PCPN COULD SNEAK UP INTO AT LEAST SOUTHERN PORTIONS OF OUR FA EARLY IN THE WEEKEND. THIS MAY ALSO ALLOW FOR A SLIGHT MODIFICATION IN TEMPERATURES WITH HIGHS PUSHING INTO THE UPPER 50S TO LOWER 60S BY THE END OF THE LONG TERM PERIOD. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/...
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LARGE SCALE UPPER LEVEL LOW CENTERED OVER THE WESTERN GREAT LAKES THIS MORNING WILL MOVE SLOWLY EAST THROUGH THE TAF PERIOD. EMBEDDED DISTURBANCES ROTATING AROUND THE LOW WILL AFFECT OUR REGION FROM TIME TO TIME. FOR TODAY...STRONG SURFACE LOW PRESSURE WILL REMAIN NORTH OF THE GREAT LAKES. MEANWHILE...A COLD FRONT WILL APPROACH THE REGION FROM THE WEST. THE INCREASING SURFACE PRESSURE GRADIENT COMBINED WITH DEEP MIXING WILL RESULT IN WINDY CONDITIONS FROM MID MORNING INTO EARLY EVENING. WINDS WILL VEER FROM A SOUTHWEST TO A WEST/SOUTHWEST DIRECTION WITH WIND GUSTS IN THE 30 TO 40 KNOT RANGE. MODELS CONTINUE TO INDICATE THAT SOME MOISTURE IN THE LOW TO MID LEVEL WILL DEVELOP/ADVECT NORTHEAST INTO THE REGION BY THIS AFTERNOON. THIS CLOUD LAYER COULD BECOME CONVECTIVE ENOUGH TO PRODUCE A FEW SPRINKLES OR LIGHT SHOWERS...MAINLY ALONG AND SOUTH OF THE OHIO RIVER. FOR TONIGHT...ONE OF THOSE EMBEDDED DISTURBANCES MENTIONED WILL DIG SOUTHEAST INTO OUR AREA. THIS FEATURE WILL TEAM UP WITH FRONTAL CONVERGENCE FROM THE ADVANCING COLD FRONT TO BRING A THREAT OF SHOWERS TO THE TAF SITES BETWEEN 06Z AND 12Z. THERE COULD BE SOME POCKETS OF MVFR VISIBILITIES ASSOCIATED WITH THE MORE ROBUST SHOWERS. OUTLOOK...GUSTY WEST TO NORTHWEST WINDS UP TO 30 KNOTS EXPECTED WEDNESDAY AFTERNOON INTO EARLY EVENING.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...WIND ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR OHZ026-034-035-042>046-051>056-060>062. KY...NONE. IN...WIND ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR INZ050. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...JGL AVIATION...HICKMAN

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