Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 121948 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 348 PM EDT FRI SEP 12 2014 .SYNOPSIS... A WEAK WEATHER DISTURBANCE PASSING EASTWARD THROUGH THE GREAT LAKES MAY LEAD TO A FEW SHOWERS ACROSS THE AREA TONIGHT. AN AREA OF COOL AND DRY HIGH PRESSURE WILL MOVE OVER THE OHIO VALLEY THIS WEEKEND. AFTER A COLD FRONT BRINGS ANOTHER CHANCE OF RAIN ON MONDAY NIGHT...ANOTHER AREA OF HIGH PRESSURE WILL CONTROL THE WEATHER THROUGH THE WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... A SHARP 500MB TROUGH IS CURRENTLY MOVING THROUGH THE UPPER MIDWEST...WITH GENERALLY SOUTHWESTERLY FLOW SEEN ALOFT. LOW PRESSURE AT THE SURFACE IS CENTERED OVER THE SOUTHEASTERN STATES...WITH COOLER NORTHEAST FLOW IN THE LOWER LEVELS OF THE ATMOSPHERE OVER THE OHIO VALLEY. DESPITE THE FORCING FROM THE APPROACH OF THE TROUGH...OVERALL MOISTURE IS RATHER LIMITED...AND CHANCES FOR PRECIPITATION DO NOT LOOK PARTICULARLY HIGH. THE ILN CWA MAY END UP SPLIT BETWEEN TWO SEGMENTS OF THE SYSTEM...WITH GREATER ATMOSPHERIC MOISTURE STAYING SOUTHEAST OF THE AREA (ASSOCIATED WITH A SURFACE TROUGH EXTENDING FROM THE SOUTHEASTERN LOW)...AND STRONGER FORCING ASSOCIATED WITH THE MID-LEVEL TROUGH REMAINING OVER MICHIGAN TO THE NORTH. WHAT MOISTURE DOES EXIST IN THE LOW LEVELS HAS HAD A VERY HARD TIME MIXING OUT TODAY...WITH THE 12Z KILN SOUNDING SHOWING A CONSIDERABLE CAP BETWEEN 900MB AND 850MB. THE CLOUD COVER FORECAST FOR TONIGHT IS PESSIMISTIC...SHOWING THE POSSIBILITY OF A FEW BREAKS IN THE NEXT FEW HOURS (ESPECIALLY IN THE SOUTHEASTERN HALF OF THE CWA) BEFORE INCREASING CONDITIONS TO CLOUDY AGAIN OVERNIGHT (AS THE TROUGH APPROACHES). MIN TEMPS APPEAR SET TO FALL SEVERAL DEGREES BELOW READINGS FROM LAST NIGHT. OUTLYING LOCATIONS IN THE NORTHERN HALF OF THE CWA MAY DROP AS FAR AS THE UPPER 40S. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... ON SATURDAY MORNING...ANY LIGHT PRECIPITATION WILL BE MOVING EAST OF THE REGION...AS THE AIR MASS ALOFT BEGINS TO CHANGE. ALTHOUGH THE SURFACE PATTERN DOES NOT SHOW MUCH (A SLIGHT INCREASE IN NW FLOW WITH SOME CONTINUED COLD ADVECTION)...THE PATTERN AT 700MB IS MUCH MORE PRONOUNCED...WITH A SHARP GRADIENT IN THETA-E ALONG THE AXIS OF THE TROUGH. BEHIND THIS...A DEEP AREA OF HIGH PRESSURE WILL BE SETTLING OVER THE GREAT LAKES AND OHIO VALLEY. THIS HIGH IS EXPECTED TO BRING COOL AND DRY CONDITIONS THROUGH THE WEEKEND. THE TEMPERATURE ANOMALIES WITH THE AIR MASS ARE NOT EXTREME...UNDER 2 STANDARD DEVIATIONS...BUT ENOUGH TO KEEP TEMPERATURES AROUND 10-15 DEGREES BELOW NORMAL FOR SATURDAY AND SATURDAY NIGHT (MODERATING SLIGHTLY ON SUNDAY). RECORDS LOOK TO BE SAFE...AND THE ONLY NUMBER EVEN CLOSE TO THE FORECAST IS THE RECORD LOW MAX FOR DAYTON ON SATURDAY (60 DEGREES...WITH A FORECAST HIGH OF 64). AFTER THE LOW CLOUDS BEGIN TO LIFT ON SATURDAY MORNING...SKY CONDITIONS WILL BECOME MORE CLEAR...WITH VERY DRY CONDITIONS EXPECTED ABOVE THE INVERSION (PRECIPITABLE WATER OF THREE TO FOUR TENTHS OF AN INCH). WITH SUN AND COLD ADVECTION...SOME DIURNAL CUMULUS OR STRATOCUMULUS DOES APPEAR POSSIBLE ON BOTH DAYS. && .LONG TERM /MONDAY THROUGH FRIDAY/... SHORT WAVE ENERGY WILL DIG ACROSS THE SOUTHERN GREAT LAKES MONDAY INTO TUESDAY...HELPING TO DRIVE A WEAK COLD FRONT DOWN THROUGH OUR AREA MONDAY NIGHT. THE 12Z ECMWF REMAINS STRONGER THAN THE 12Z GFS WITH THIS FEATURE WHILE THE 12Z CMC IS SOMEWHAT IN BETWEEN. WILL GENERALLY TAKE A MODEL BLEND WHICH LINES UP FAIRLY CLOSELY WITH THE ONGOING FORECAST. THIS WILL ALLOW FOR SOME LOWER CHANCE POPS TO DEVELOP OVER OUR NORTHWEST MONDAY AFTERNOON AND THEN OVERSPREAD THE REMAINDER OF THE AREA MONDAY NIGHT. SURFACE HIGH PRESSURE AND A SEASONABLY COOL AIRMASS WILL THEN BUILD DOWN INTO THE AREA THROUGH THE REST OF THE WEEK. IT LOOKS LIKE A WEAKENING COLD FRONT WILL DROP DOWN ACROSS THE LOWER GREAT LAKES WEDNESDAY INTO WEDNESDAY NIGHT...BUT PRETTY MUCH WASH OUT AS IT PUSHES SOUTH TOWARD OUR AREA. WILL THEREFORE MAINTAIN A DRY FORECAST THROUGH THE REMAINDER OF THE PERIOD. HIGHS WILL BE IN THE UPPER 60S TO LOWER 70S THROUGH THURSDAY...WITH PERHAPS A BIT OF A WARM UP AS WE START TO GET INTO SOME RETURN FLOW TOWARD FRIDAY. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... LATEST VISIBLE SATL IMGRY CONTINUES TO SHOW EXTENSIVE AREA OF LOW CLOUDS OVER THE TAF SITES. EXPECT MAINLY MVFR CIGS WHICH WILL LKLY IMPROVE TO VFR FOR A PERIOD LATE THIS AFTN INTO THIS EVENING. MID LEVEL PROGRESSIVE S/W WILL TRACK THRU THE GREAT LAKES OVERNIGHT/EARLY SATURDAY. A FEW SPRINKLES OR LIGHT RAIN SHOWERS WILL BE POSSIBLE LATE BUT DEEP MSTR IS LACKING AND GENERALLY OF MODEL SOLNS INDICATING THAT ILN/S TAFS WILL BE IN A SPLIT BETWEEN RAIN AREAS. HAVE MVFR CIGS RE-DEVELOPING OVERNIGHT BUT CAN NOT RULE OUT A PERIOD OF IFR CIGS TOWARD SUNRISE. SFC HIGH PRESSURE WILL NOSE IN FROM THE WEST WITH LOW CIGS LIFTING AND VFR CONDITIONS DEVELOPING FROM THE WEST BY AFTN AS IT PASSES. NORTHEAST WINDS AT 10 KTS OR LESS WILL BACK TO THE W-NW THIS EVENING AND THEN VEER TO THE NORTH ON SATURDAY. OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED AT THIS TIME. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...JGL AVIATION...AR

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