Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 250602 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 202 AM EDT FRI JUL 25 2014 .SYNOPSIS... HIGH PRESSURE RESPONSIBLE FOR DRY AND COOL WEATHER OVER THE OHIO VALLEY WILL SLIDE SOUTHEAST ACROSS OHIO INTO THE APPALACHIANS TONIGHT AND FRIDAY...PROVIDING A VERY COMFORTABLE NIGHT WITH LOWS IN THE 50S. A FEW RECORD LOWS WILL BE POSSIBLE. RETURNING SOUTHERLY FLOW FRIDAY NIGHT AND SATURDAY ON THE BACKSIDE OF THE HIGH FRIDAY NIGHT AND SATURDAY WILL ALLOW FOR INCREASED WARMTH AND MOISTURE...AND WITH THAT WILL COME THE POTENTIAL FOR SEVERAL CLUSTERS OF SHOWERS AND THUNDERSTORMS LATER FRIDAY NIGHT THROUGH THE ENTIRE WEEKEND. SEVERE WEATHER WILL BE POSSIBLE AS THE NEXT IN A SERIES OF VERY STRONG COLD FRONTS APPROACHES FROM THE NORTHWEST. THIS NEXT FRONTAL PASSAGE WILL BRING YET ANOTHER COOL WEEK WITH MUCH OF NEXT WEEK EXPECTED TO REMAIN WELL BELOW NORMAL IN TERMS OF TEMPERATURE. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... EVENING UPDATE WAS TO TREND OBSERVED VALUES TO THE FORECAST THAT WAS ALREADY IN THE BOOKS. CLOUD COVER WILL CONTINUE TO DISSIPATE THIS EVENING BRINGING MOSTLY CLEAR SKIES AND A STRONG RADIATIONAL COOLING EVENT TO THE AREA. WITH DEWPOINTS CURRENTLY IN THE LOW-MID 50S...A RAPID EVENING TEMP DROP IS EXPECTED. RECORD LOW TEMPERATURES AT THE THREE CLIMATE SITES ARE AS FOLLOWS... COLUMBUS /CMH/...52F IN 1911 CINCINNATI /CVG/...56F IN 1931 DAYTON /DAY/...50F IN 1906 THE CINCINNATI RECORD IS IN JEOPARDY...WILL BE VERY CLOSE BASED ON TIGHT STATISTICAL GUIDANCE CLUSTERING IN THE MID 50S. SOME TYPICAL COOL SPOTS MAY DROP INTO THE UPPER 40S. WITH THE HIGH MOVING RIGHT OVERHEAD AROUND SUNRISE THINK POTENTIAL IS CERTAINLY THERE. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/... THIS PERIOD WILL BE CHARACTERIZED BY A LARGE SWING/CHANGE IN AIRMASSES AND QUIESCENT WEATHER ON FRIDAY MORNING TO POTENTIAL SEVERE STORMS AND HEAVY RAINFALL BY SATURDAY NIGHT. AT 25.12Z...595DM 500MB ANTICYCLONE WILL REMAIN SITUATED OVER NEW MEXICO WITH A VERY DYNAMIC AND ANOMALOUS CLOSED LOW CRESTING THE RIDGE OVER SASK/ALBERTA...FLATTENING THE RIDGE SOMEWHAT. THE PERSISTENT ERN CONUS LONGWAVE TROUGH WILL STILL EXIST IN A POSITIVE TILT FASHION FROM LA/AL NORTHEAST THROUGH THE UPPER OHIO VALLEY WHERE A CYCLONE WILL EXIST EAST OF HUDSON BAY. THROUGH THE DAY FRIDAY...THE CLOSED LOW WILL MOVE SLOWLY EASTWARD WHILE THE RIDGE IN THE WEST FLATTENS...WHICH DEAMPLIFIES THE ERN CONUS LONGWAVE TROUGH FURTHER AND SHUNTS IT EAST. AS SUCH...SFC HIGH PRESSURE AND COOL/DRY WEATHER WILL BUILD EASTWARD WITH RETURN FLOW BEGINNING TO OUR WEST. THE BULK OF FRIDAY WILL BE GORGEOUS...LOW HUMIDITY...MIX OF SUN AND CLOUDS AND TEMPS REBOUNDING INTO THE UPPER 70S. THAT IS WHERE MORE SIGNIFICANT CHANGES BEGIN AND THE ENTRY POINT INTO WHAT WILL LIKELY BE AN ACTIVE WEEKEND. BY SATURDAY MORNING THE POTENT CLOSED LOW WILL BE APPROACHING LAKE WINNIPEG WHILE A MORE SUBTLE SHORTWAVE TROUGH IS EJECTED ATOP THE FLATTENING NERN QUADRANT OF THE WRN RIDGE...DOWN THE SLIDE OF INCREASINGLY FAST WNWLY MID LEVEL FLOW INTO THE GREAT LAKES. ON THE NOSE OF A LOW LEVEL MOISTURE TRANSPORT MAXIMUM...AND AT THE EDGE OF AN STRONG PLAINS-BASED ELEVATED MIXED LAYER /WARM...DRY...STEEP LAPSE RATE ENVIRONMENT/...CONVECTIVE INSTABILITY WILL BE ADVECTED IN FROM THE WEST LATER FRIDAY NIGHT WITH MUCAPE SIGNIFICANTLY INCREASING ABOVE THE EML LATER IN THE NIGHT. AN MCS OR TWO IS LIKELY TO BE MANIFESTED ON THE LEADING EDGE OF THESE ENTITIES...AND WILL BE APPROACHING THE AREA FRIDAY NIGHT/SAT MORNING WITH TIMING/LOCATION VERY MUCH IN DOUBT. PWAT WILL DOUBLE /0.60" TO 1.20"/ IN LESS THAN 12 HOURS AS THIS DESTABILIZATION ALOFT TAKES PLACE. CONFIDENCE ON WHERE THIS ACTIVITY MOVES IS NOT HIGH...BUT DID INCREASE THE SHOWER/STORM CHANCES FRIDAY NIGHT INTO SATURDAY MORNING OVER A LARGE PORTION OF THE AREA TO ACCOUNT FOR THIS POTENTIAL. PER 25.12Z ECMWF/GFS/NAM...SOMEWHERE IN INDIANA/NORTHERN OHIO SEEMS THE BEST BET AT 12Z SAT MORNING. AS THE REMNANTS OR WHAT REMAINS OF ANY STORM ACTIVITY MOVES ACROSS THE AREA SATURDAY MORNING...HEIGHTS WILL CONTINUE TO SLOWLY RISE IN THE WAKE OF THE LEAD SHORTWAVE TROUGH AND AHEAD OF THE POTENT CLOSED LOW NOW DIGGING INTO MINNESOTA. THE EML WILL BECOME ENTRENCHED OVER THE AREA WITH POINT FCST /BUFR/ SOUNDINGS FROM 25.12Z NAM AND GFS BOTH SHOWING STRONG INHIBITION FROM LATE MORNING THROUGH THE BULK OF THE AFTERNOON. THUS...ATTEMPTED TO SHOW A REDUCTION IN RAIN CHANCES DURING THIS TIME...AS MLCINH ON MANY SOUNDINGS EXCEEDS 200 J/KG AND IN SOME DATA EXCEEDS 300 J/KG. THIS SHOULD PROMOTE A WARM...INCREASINGLY HUMID DAY WITH DECREASING ELEVATED STORM THREATS...WITH DEWPOINTS RISING TOWARD 70F AND AIR TEMPS IN THE MID/UPPER 80S. SATURDAY EVENING/OVERNIGHT...CONFIDENCE IS LOW ON THE DETAILS BUT A RENEWED LOW LEVEL JET/MOISTURE TRANSPORT SIGNAL WILL DEVELOP AHEAD OF THE DIGGING MN/WI CLOSED LOW...POINTED INTO IL/IN/OH. THERE MAY BE OUTFLOW/DIFFERENTIAL HEATING BOUNDARIES FROM SAT MORNING CONVECTION...BUT EITHER WAY FORCING BECOMES GOOD ENOUGH AND A SIGNAL CROPS UP IN THE DATA FOR NOCTURNAL MCS POTENTIAL...WHICH COULD BE ANYWHERE FROM OHIO BACK INTO ILLINOIS. THIS MAY BE INITIALLY ROOTED ABOVE THE CAP BUT GIVEN RESERVOIR OF STRONG INSTBY AMIDST THE EML...AND IMPRESSIVE SHEAR...THERE IS CONCERN FOR AN ORGANIZED SEVERE WEATHER EVENT SAT NIGHT INTO SUNDAY MORNING WITH PRIMARY FOCUS OF DAMAGING WIND VIA FORWARD PROPAGATING CONVECTIVE SYSTEM. IN FACT...CIPS ANALOGS INDICATES THAT THE SYNOPTIC PATTERN INGREDIENTS AS BEING PREDICTED BY THE 25.12Z NAM HAS PRODUCED A NUMBER OF WIND-PRODUCING MCS SYSTEMS ACROSS THE CORN BELT/OHIO VALLEY. A CLOSER LOOK AT THE DETAILS /EVENTS WITHIN THE PATTERN MATCH -- TOP 15 ANALOGS ON VARIOUS DOMAINS/ SHOWS A COUPLE HIGHER-END EVENTS OF EITHER IN TERMS OF AREA AFFECTED OR NUMBER OF REPORTS...AND THESE SIGNALS WERE PRESENT ON 25.00Z GFS PATTERN MATCHES...SO FEEL CONFIDENT IN BEGINNING TO RAISE AWARENESS OF THIS POTENTIAL IN HAZ WX OUTLOOK PRODUCT FOR SAT INTO SUNDAY. DEGREE OF INSTBY AND 0-3KM SHEAR ARE FAVORABLE. LURKING IN THE TALL GRASS IS HEAVY RAIN POTENTIAL WITH GEFS REFORECAST PROBABILITIES SUGGESTING THAT RAIN AMOUNTS BEING SUGGESTED BY ENSEMBLE MEAN /ALREADY DECENT/ MAY ACTUALLY BE UNDERDONE IN THIS MULTI-MCS SCENARIO OVER SATURDAY/SUNDAY. WPC ALREADY RUNNING SLGT RISKS FOR EXCESSIVE RAINFALL ON DAY 3 /SAT AND SAT NIGHT/ WHICH SEEMS REASONABLE BASED ON REFORECAST DATA AND 25.12Z DETERMINISTIC RUNS SHOWING MCS POTENTIAL. 25.00Z NAEFS PROBABILITIES ALSO CENTERED ON OHIO. WLY LOW LEVEL JET AHEAD OF A DIGGING UPPER TROUGH /WHICH IS THE PATTERN ON SUNDAY MORNING/ MAY PROMOTE BACKBUILDING AND TRAINING ON THE SRN FRINGE OF ANY FORWARD PROPAGATING MCS. && .LONG TERM /SUNDAY THROUGH THURSDAY/... ACTIVE WEATHER PATTERN WILL BE IN PLACE FOR THE BEGINNING OF THE LONG TERM PERIOD. MODELS ARE IN GOOD AGREEMENT ON A MCS MOVING ACROSS THE FA SUNDAY MORNING. THIS FEATURE WILL BRING WIDESPREAD THUNDERSTORM ACTIVITY ACROSS THE AREA. WITH MODEL AGREEMENT INCREASED PRECIPITATION CHANCES SIGNIFICANTLY DURING THIS TIME. THERE IS A DECENT CHANCE OF SEVERE WEATHER WITH THIS FEATURE WITH DAMAGING WINDS THE PRIMARY THREAT. AN ISOLATED TORNADO CANNOT BE RULED OUT HOWEVER. WILL ADD MENTION OF THIS THREAT TO THE HWO. IN ADDITION TO THE SEVERE THREAT THIS FEATURE WILL BRING MODERATE TO HEAVY RAIN TO THE AREA WHICH MAY LEAD TO SOME FLOODING ISSUES AS WELL. ADDITIONAL THUNDERSTORM ACTIVITY WILL BE LIKELY DURING THE AFTERNOON AND EVENING HOURS ON SUNDAY AS A COLD FRONT APPROACHES AND WORKS INTO THE REGION. THERE IS QUITE A BIT OF INSTABILITY ACROSS THE AREA FOR SUNDAY. THERE IS THE ADDITIONAL CHANCE FOR SEVERE WEATHER SUNDAY AFTERNOON INTO THE EVENING HOURS. DAMAGING WINDS AND LARGE HAIL WILL BE POSSIBLE. IN ADDITION A TORNADO THREAT WILL ALSO BE POSSIBLE. SOME QUESTIONS REMAIN ON THE STRENGTH OF THIS SECOND EVENT AS THIS WILL BE DEPENDENT ON THE FIRST ROUND OF THUNDERSTORMS. WILL ALSO HIGHLIGHT THIS SEVERE THREAT IN THE HWO. WITH MULTIPLE ROUNDS OF SHOWERS AND THUNDERSTORMS THERE WILL AGAIN BE THE THREAT OF FLOODING. THUNDERSTORMS MOVE OUT OF THE FA SUNDAY NIGHT AND COOLER AIR WILL BE USHERED INTO THE FA. AN UPPER LEVEL DISTURBANCE ON MONDAY WILL ALLOW FOR DECENT CLOUD COVER AND SOME SHOWER ACTIVITY. THIS WILL KEEP TEMPERATURES COOL AND WELL BELOW NORMAL. HIGH TEMPERATURES ARE ONLY EXPECTED TO BE IN THE LOW TO MID 70S ON MONDAY. HIGH PRESSURE THEN WORKS INTO THE AREA FOR THE REMAINDER OF THE LONG TERM ALLOWING FOR DRY CONDITIONS. HIGH TEMPERATURES WILL GRADUALLY WARM EACH DAY AFTER TUESDAY. TUESDAY LOOKS TO HAVE TO COOLEST HIGH TEMPERATURES OF THE LONG TERM PERIOD. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... HIGH PRESSURE WILL KEEP CLEAR SKIES AND LIGHT WINDS ACROSS THE REGION THROUGH THE MORNING. IFR RIVER FOG WILL BE LIKELY AT KLUK THIS MORNING. KILN/KLCK MAY SEE SOME FOG DEVELOPMENT AS WELL. HOWEVER...THOSE LOCATIONS ARE EXPECTED TO REMAIN MVFR OR BETTER. ALL FOG WILL BURN OFF SHORTLY AFTER SUNRISE. SCT FAIR WEATHER CU WILL DEVELOP BY THE AFTERNOON WITH WINDS BECOMING SOUTH TO SOUTHWESTERLY AS HIGH PRESSURE SHIFTS EAST OF THE REGION. CLOUD COVER WILL BEGIN TO INCREASE LATE FRIDAY EVENING WELL AHEAD OF AN APPROACHING STORM SYSTEM. OUTLOOK...THUNDERSTORMS POSSIBLE SATURDAY INTO SUNDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...BINAU NEAR TERM...BINAU/FRANKS SHORT TERM...BINAU LONG TERM...NOVAK AVIATION...LATTO

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