Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 171038 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 638 AM EDT WED SEP 17 2014 .SYNOPSIS... HIGH PRESSURE WILL KEEP DRY CONDITIONS ACROSS THE AREA THROUGH SATURDAY. A COLD FRONT WILL APPROACH THE AREA ON SUNDAY BRINGING THE NEXT CHANCE FOR SHOWERS AND THUNDERSTORMS. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... STRATUS DECK FROM 3-4KFT IS DEVELOPING OVER CWA AND LIMITING MOST OF THE AREA FROM SEEING ANY FOG BECOMING DENSE. THE STRATUS WILL MIX OUT AS DAYLIGHT HITS THE COLUMN AND GENERALLY SUNNY SKIES WITH FAIR WX CU IS EXPECTED FOR THE REMAINDER OF THE DAY. HIGHS WILL TOP OUT WITHIN A FEW DEGREES OF 70 ACROSS MUCH OF THE REGION. THE AXIS OF THE HIGH PRESSURE WILL BE CENTERED OVER THE REGION WITH GENERALLY LIGHT WINDS TURNING NORTHWEST BY THE END OF THE DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... A GENERALLY BENIGN WEATHER PATTERN WITH THE HIGH PRESSURE SETTLED OVER THE REGION WILL BE IN THE OFFING FOR THE REST OF THE WORK WEEK. NORTH WINDS WILL PUSH THE CORE OF COLD AIR OVER THE CWA EARLY THURSDAY...AND HIGHS WILL ONLY BE A DEGREE OR TWO WARMER THAN WEDNESDAY WITH SUNNY SKIES. WITHOUT THE COLD PUSH...THE CLEAR SKIES WOULD NORMALLY INDICATE A GOOD 5-7 DEGREE INCREASE FROM THE PREVIOUS DAY GIVEN THE DRY AIRMASS AND SUNNY SKIES. THIS INCREASE IN HIGHS WILL OCCUR ON FRIDAY WHEN READINGS ACROSS THE REGION RISE TO THE MIDDLE AND UPPER 70S. THE AXIS OF THE HIGH WILL SLIDE EAST ON FRIDAY AND SOUTHEAST WIND WILL TURN SOUTHWEST FRIDAY NIGHT. OVERNIGHT LOWS THROUGH THE PERIOD WILL BE IN THE 40S UNDER GENERALLY GOOD RADIATIONAL COOLING...RISING INTO THE 50S BY FRIDAY NIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... SURFACE HIGH PRESSURE WILL CENTERED OVER SOUTHERN ONTARIO AND QUEBEC ON FRIDAY MORNING...MOVING OFF THE EAST COAST BY SATURDAY MORNING. ALONG WITH A SHORT-TERM FLATTENING OF THE MID-LEVEL PATTERN...LEADING TO HEIGHT RISES OVER THE OHIO VALLEY AS THE EAST COAST TROUGHING DISSIPATES...THIS WILL SIGNAL A PATTERN CHANGE HEADING INTO THE WEEKEND. AS A RESULT...SURFACE WINDS WILL TAKE A SOUTHERLY COMPONENT...LEADING TO A WARM ADVECTION PATTERN FOR FRIDAY AND SATURDAY. THE REMAINING INFLUENCE OF THE SURFACE HIGH WILL PROVIDE FOR A DRY STARTING POINT...AND MOSTLY SUNNY CONDITIONS. THE WARM ADVECTION PATTERN WILL STRENGTHEN ON SATURDAY...WITH SURFACE WINDS TURNING TO THE SSW...AND A TROUGH OVER THE NORTHERN PLAINS BEGINNING TO GET A LITTLE CLOSER TO THE AREA. FRIDAY TEMPERATURES WILL LIKELY STILL REMAIN JUST BELOW NORMAL...BUT NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES ARE EXPECTED WITH THE WARMER FLOW ON SATURDAY. THROUGH SATURDAY...FORECAST MODEL AGREEMENT IS STRONG. AS THE TROUGH APPROACHES THE OHIO VALLEY ON SUNDAY MORNING...SURFACE LOW PRESSURE IS EXPECTED TO DEVELOP IN THE NORTHERN GREAT LAKES. A COLD FRONT WILL EXTEND SOUTH FROM THIS LOW...AND WILL MOVE THROUGH THE ILN CWA ON SUNDAY. THESE BASIC DETAILS ARE FAIRLY CERTAIN...BUT THERE IS MUCH GREATER MODEL SPREAD IN THE SPECIFICS OF HOW THE TROUGH AND FRONT ARE BEING DEPICTED. THE AMPLITUDE OF THE UPPER TROUGH...IN PARTICULAR...SHOWS MARKED DIFFERENCES BETWEEN THE GFS AND ECMWF (AND EVEN WITHIN THE INDIVIDUAL GFSE MEMBERS). AMONG THE FLATTEST SOLUTIONS IS THE 12Z ECMWF...WHICH PIVOTS THE FRONT IN AN ORIENTATION THAT WOULD PROVIDE LITTLE IN THE WAY OF FORCING OR SHEAR OVER THE OHIO VALLEY. THE 12Z OPERATIONAL GFS IS AMONG THE STRONGEST SOLUTIONS...WITH A CLOSED 500MB LOW THAT IS NOT SUPPORTED BY ITS ENSEMBLE MEMBERS. THUS...IT IS NOT SURPRISING THAT TIMING AND STRENGTH DIFFERENCES WITH THE SURFACE FRONT ARE A FORECAST CHALLENGE. THOUGH PRECIPITATION IS FAIRLY LIKELY TO OCCUR ON SUNDAY FOR THE ILN CWA...POPS HAVE BEEN LIMITED TO 40 PERCENT UNTIL TIMING AGREEMENT IN THE MODELS BECOMES STRONGER. ALSO UNCERTAIN IS THE EVENTUAL MAGNITUDE OF THE FLOW ALOFT AND WARM ADVECTION AT THE SURFACE...WHICH WILL CERTAINLY IMPACT WHETHER OR NOT SHEAR AND INSTABILITY (RESPECTIVELY) ARE ABLE TO BECOME A CONCERN. BEHIND THE FRONT (FROM SUNDAY NIGHT INTO NEXT WEEK)...A COOLER AND DRIER AIR MASS OF CANADIAN ORIGIN WILL MOVE INTO PLACE. THIS LARGE AREA OF HIGH PRESSURE IS FORECAST TO COVER A SIGNIFICANT PORTION OF THE MIDWESTERN STATES AND INTO THE OHIO VALLEY. AFTER A DAY ON SUNDAY THAT IS LIKELY TO FEATURE A TEMPERATURE GRADIENT (WITH WARM CONDITIONS REMAINING IN THE SOUTHEASTERN CWA)...THE FIRST PART OF THE WEEK WILL FEATURE TEMPERATURES FALLING WELL BELOW NORMAL. && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... AREA OF STRATUS HAS DEVELOPED ACROSS THE MAJORITY OF THE TAFS. THE WESTERN EDGE OF THE DECK HAS SOME MVFR CIGS IN IT. THE CLOUDS HAVE HELPED MITIGATE SOME OF THE DENSE FOG. EXPECT THE STRATUS TO LINGER ACROSS THE TAFS FOR THE MORNING HOURS BEFORE SCATTERING OUT AROUND NOON. AN H5 S/WV IS FORECAST TO PUSH INTO THE AREA AFT 18Z. EXPECT SOME MID LEVEL CLOUDS WITH THE PASSAGE OF THE S/W. MODELS ARE SUGGESTING THAT THE SRN TAFS WILL BE AFFECTED BY MORE MID CLOUDS THAN THE NRN TAFS. BACK EDGE OF THE AC WILL WORK EAST OF THE TAFS BY 06Z...LEAVING JUST SOME SCT CLOUDS AND THE POSSIBILITY OF SOME SCATTERED MVFR FOG. OUTLOOK...THUNDERSTORMS POSSIBLE SUNDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...FRANKS NEAR TERM...FRANKS SHORT TERM...FRANKS LONG TERM...HATZOS AVIATION...SITES

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