Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 210555 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 155 AM EDT THU AUG 21 2014 .SYNOPSIS... A FRONTAL ZONE WILL SETTLE INTO THE OHIO VALLEY TONIGHT. THIS FRONT WILL GRADUALLY LIFT NORTHEAST INTO THE GREAT LAKES THROUGH THE WEEKEND. DISTURBANCES WILL INTERACT WITH A MOIST AIRMASS TO PRODUCE SHOWERS AND THUNDERSTORMS AT TIMES THROUGH THE PERIOD. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... DRY CONDITIONS WILL START OUT THE NEAR TERM. A FEW ISOLATED SHOWERS ARE DEVELOPING OVER NW OHIO AND ALSO SE INDIANA. THE HI RES MODELS ARE PICKING UP ON THIS RATHER WELL AND SHOWING ADDITIONAL DEVELOPMENT INTO NW PORTIONS OF THE FA DURING THE OVERNIGHT HOURS. INCREASED PRECIPITATION CHANCES IN THIS AREA OVERNIGHT HOWEVER EXPECT MOST OF THE MORE WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY TO HOLD OFF UNTIL THE EARLY DAYTIME HOURS ON THURSDAY. TEMPERATURES HAVE DROPPED OFF INTO THE 60S ACROSS PORTIONS OF THE AREA. UPPER 60S ARE MORE WIDESPREAD ACROSS NE PORTIONS OF THE FA WHERE THERE IS LESS CLOUD COVER. THE RATE OF COOLING WILL SLOW OVERNIGHT AS ADDITIONAL CLOUDS MOVE INTO THE AREA HOWEVER EXPECT MOST LOCATIONS TO DROP DOWN INTO THE 60S OVERNIGHT. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... THERE IS A LARGE VARIATION IN MODEL SOLUTIONS FOR THURSDAY. PREFER A NAM/CMC REGIONAL/HIRES-WRF SOLUTION WHICH DROPS H5 ENERGY INTO THE REGION EARLY THURSDAY MORNING IN THE NW FLOW. THEY PUSH THE BEST PCPN CHANCE ACROSS THE REGION DURING THE MORNING...AND EXIT IT OUT OF THE EAST DURING THE AFTN. THURSDAY NIGHT BETTER FORCING SHIFTS TO NRN OHIO AS CONVERGENCE ALONG A LIFTING WARM FRONT MOVES ALSO. PUT HIGH CHANCE POPS IN THE NORTHERN COUNTIES WITH DECREASING POPS DOWN TO THE SW. ON FRIDAY...ADDITIONAL H5 ENERGY TOPS THE RIDGE AND DROPS SE ACROSS THE REGION. THIS WILL HELP DEVELOP DAYTIME CONVECTION...BUT CENTRAL OHIO WILL HAVE THE BEST CHANCE AT SEEING CONVECTION AS IT IS CLOSER TO THE WARM FRONT. CONVECTION TOMORROW WILL COMPLICATE THE HIGH TEMPERATURE FORECAST. ONLY WENT LOWER 80S IN THE NW COUNTIES SINCE THE CONVECTION SHOULD LIMIT HEATING THERE. SOUTHERN COUNTIES SHOULD BE ABLE TO MAKE THE MID TO UPPER 80S. AFTER DROPPING DOWN TO ONLY AROUND 70 THURSDAY NIGHT...FRIDAY IS LOOKING LIKE A HOT AND HUMID DAY. OHIO RIVER COUNTIES SHOULD SEE TEMPERATURES PUSH INTO THE LOWER 90S WITH DEWPOINTS IN THE LOWER 70S. THIS WILL PUSH HEAT INDICES OVER 100. WILL CONTINUE TO HIGHLIGHT THE THREAT IN THE HWO. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AT 12Z ON SATURDAY...THE 20.12Z ECMWF AND GFS ARE VERY GOOD AGREEMENT ON THE LARGE SCALE PATTERN WITH AN AMPLIFIED FLOW PATTERN OVER THE LOWER 48. A DEEP CLOSED LOW SHOULD BE OVER ID/MT WITH A STRONG SUBTROPICAL RIDGE EXTENDING NORTHEAST FROM A 593DM HIGH OVER ALABAMA. ANOMALOUS MOISTURE WILL STILL BE IN PLACE WITH PWAT FROM 1.5 TO 2.0 STANDARD DEVIATIONS ABOVE CLIMO. THROUGH THE WEEKEND THE STRONG CLOSED LOW WILL SWING NORTHEAST INTO THE NRN HIGH PLAINS AND EVENTUALLY INTO SASK...WHILE THE RIDGE EXPANDS NORTHEASTWARD INTO TN/ARK. DESPITE WEAK FORCING...CONTINUED NORTHERLY/NORTHWESTERLY FLOW AROUND THE RIDGE...THE PRESENCE OF A WEAK SURFACE TROUGH...AND ANOMALOUS MOISTURE SHOULD CONTINUE TO ALLOW FOR STRONG DAYTIME INSTBY BOTH SAT AND SUN. THE POTENTIAL FOR ONE MORE CLUSTERS OF SSE PROPAGATING STORM CLUSTERS WILL CONTINUE THROUGH THE WEEKEND. GIVEN THE MAGNITUDE OF INSTBY...EVEN WITH WEAKENING FLOW WITH TIME...THERE COULD BE STRONG/SEVERE STORM THREAT ON EITHER OF THESE DAYS IF A ORGANIZED COLD POOL COULD FORM. GETTING INTO MONDAY-TUESDAY...THE RIDGE CONTINUES TO BUILD WITH HEAT/HUMIDITY. FLOW BECOMES VERY LIGHT THROUGH THE BULK OF THE TROPOSPHERE AND IT BECOMES QUESTIONABLE IF COVERAGE OF DAYTIME/EVE STORMS WARRANTS MENTION. RIGHT NOW HAVE RUN 15-25% RAIN CHANCES BOTH OF THESE DAYS...AND THAT MAY BE TOO HIGH. INTO WEDNESDAY...SOME HINTS OF HEIGHT FALLS WHICH MAY ALLOW A LITTLE STRONGER FLOW OR A WEAK SHORTWAVE TROUGH TO CROSS THE GREAT LAKES. SO A BETTER STORM THREAT THEN...HOWEVER AT THIS TIME RANGE THIS IS A VERY LOW CONFIDENCE FORECAST GIVEN CONDITIONAL NATURE OF THE RIDGE BUCKLING. SO ALL IN ALL...HAVE TENDED TO FOCUS RAIN CHANCES NEAR PEAK HEATING INTO THE EVENING AND ALLOW FOR SOME DRY NIGHTS/EARLY MORNINGS. FLY IN OINTMENT WILL BE ANY FORWARD PROPAGATING MCS THAT SURVIVES THROUGH THE NIGHT...ORIGINATING TO OUR NORTHWEST AND FALLING DOWN NNWLY FLOW EITHER SATURDAY MORNING OR SUNDAY MORNING. LOW CONFIDENCE STORM CHANCE...BUT HIGH CONFIDENCE WARM/HUMID PATTERN IS THE STORY FOR THE SAT-WED TIMEFRAME. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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THE REGION WILL BE WEDGED BETWEEN TWO SYNOPTIC SCALE SYSTEMS OVER THE NEXT 24 HOURS. A MID LEVEL CLOSED LOW SLOWLY MOVING FROM THE EASTERN GREAT LAKES TO NEW ENGLAND AREA. MEANWHILE...A MID LEVEL RIDGE WILL TRY TO NUDGE ITS WAY NORTHWARD INTO THE MIDDLE MISSISSIPPI VALLEY. OUR AREA WILL BE INFLUENCED BY THE NORTHWEST FLOW ALOFT BETWEEN THESE TWO SYSTEMS ALONG WITH EMBEDDED DISTURBANCES RIDING SOUTHEAST ON THE EAST SIDE OF THE RIDGE AXIS FROM TIME TO TIME. AT THE SAME TIME...A WEAK TO MODEST LOW LEVEL JET WILL BRING SOME LOW LEVEL MOIST ASCENT. MANY MODEL SOLUTIONS...INCLUDING THE CONVECTION ALLOWING MODELS...CONTINUE TO STRUGGLE WITH TIMING AND PLACEMENT OF CONVECTION OVER THE NEXT 24 HOURS. THERE IS SOME CONSENSUS IN AT LEAST THE FIRST 12 HOURS. A WEAK DISTURBANCE OVER NRN INDIANA IS EXPECTED TO MOVE SOUTHEAST ACROSS NRN OHIO THIS MORNING. ALSO...A LOW LEVEL JET IS FORECAST TO IMPINGE ON THE REGION FROM THE WEST. WE SHOULD SEE AN INCREASE IN SHOWERS AND THUNDERSTORMS THIS MORNING...ESPECIALLY BETWEEN 12Z AND 18Z. HAVE PLACED TEMPO MVFR CONDITIONS AT ALL THE TAF SITES. FOR THIS AFTERNOON...SOME MODELS SUGGEST WE COULD BE IN A RELATIVE LULL AS THE LOW LEVEL JET DIURNALLY WEAKENS AND THE DISTURBANCE MOVES AWAY. HAVE LEFT A VCSH DESCRIPTOR AT THE TAF SITES FOR LOW CHANCES FOR SHOWERS OR A STORM. FOR TONIGHT...ANOTHER EMBEDDED DISTURBANCE IS FORECAST TO ROTATE SOUTHEAST INTO THE REGION. THERE CONTINUES TO BE DIFFERENCES IN THE EVOLUTION OF NOCTURNAL CONVECTION. RIGHT NOW..THE BEST CHANCE FOR SHOWERS/STORMS SHOULD OCCUR AFTER 06Z AND BE MORE WEIGHTED TOWARDS THE NORTHERN TAF SITES OF KDAY...KCMH...AND KLCK. HOWEVER...IT SHOULD BE NOTED THAT SOME MODELS HAVE CONVECTION AFFECTING THE ENTIRE REGION IN THE FORM OF A MESOSCALE CONVECTIVE SYSTEM. WILL CONTINUE TO MONITOR MODEL TRENDS FOR TIMING AND SPATIAL COVERAGE. OUTLOOK...THUNDERSTORMS POSSIBLE FRIDAY EVENING THROUGH SUNDAY.
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&& .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...SITES/SNYDER NEAR TERM...NOVAK SHORT TERM...SITES LONG TERM...BINAU AVIATION...HICKMAN

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