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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
401 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/...
AFTER MORNING FOG BURNS OFF...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 /07Z WEDNESDAY THROUGH SUNDAY/...
SC HAS FINALLY DISSIPATED UNDER THE SUBSIDENCE OF BUILDING HIGH
PRESSURE. WITH LIGHT WINDS AND LINGERING LOW LEVEL MOISTURE...
EXPECT FOG FORMATION EARLY THIS MORNING. BROUGHT IN MVFR VSBYS AT
THE CVG/DAY/CMH. AT THE OTHER 3 TAFS WENT WITH IFR VSBYS AND/OR
CEILINGS.

AFT 12Z...THE FOG WILL BURN OFF. THE HIGH WILL REMAIN OVER THE
REGION....BUT DIURNAL CU WILL DEVELOP AFT 14Z. 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.

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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