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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
1225 AM EST SAT DEC 20 2014

.SYNOPSIS...
WEAK SURFACE HIGH PRESSURE WILL SLOWLY MOVE EAST THROUGH THE 
WEEKEND. SOUTHERLY FLOW ON THE BACK SIDE OF THE HIGH WILL LEAD TO A 
WARM UP EARLY NEXT WEEK AND INCREASING PRECIPITATION CHANCES. THEN A
STRONG LOW PRESSURE SYSTEM WILL TRACK THROUGH THE REGION AT MIDWEEK 
BRINGING WINDY CONDITIONS AND RAIN CHANGING TO SNOW.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A SHALLOW AREA OF SATURATION...NEAR 900MB-875MB...HAS BEEN PRESENT FOR
MOST OF THE WEEK. THE 00Z KILN SOUNDING TONIGHT SHOWS MUCH OF THE
SAME...WITH THIS MOISTURE TRAPPED UNDERNEATH A VERY SHARP
INVERSION. THE ONLY EROSION OF THE CLOUD LAYER HAS BEEN ACROSS
SOUTHERN MICHIGAN AND NORTHERN INDIANA. FROM A METEOROLOGICAL
STANDPOINT...IT SHOULD BE NOTED THAT SOME CLEARING OF THE
LOW-LEVEL CLOUDS APPEARS LIKELY IN THE NORTHWESTERN ILN CWA. THERE
ARE ALSO SIGNS OF SOME DISSIPATION SOUTH OF THE OHIO RIVER.
HOWEVER...IN TERMS OF PUTTING A FORECAST TOGETHER...THE HIGH
CLOUDS IN ADVANCE OF THE NEXT WEATHER SYSTEM (WHICH WILL PASS
COMFORTABLY SOUTH OF THE AREA TOMORROW) ARE ALREADY MOVING IN.
THUS...EVEN WHERE SOME SLIGHT CLEARING OCCURS IN THE LOW
LEVELS...HIGH CLOUDS WILL BE IN PLACE.

THIS MAY BE A FEW TOO MANY WORDS TO DESCRIBE WHAT IS ESSENTIALLY A
PERSISTENCE FORECAST FROM THE PAST FEW DAYS...WITH CLOUDY
CONDITIONS AND A SMALL DIURNAL RANGE. VERY FEW CHANGES WERE
NECESSARY FOR THE GRIDS THIS EVENING.

PREVIOUS DISCUSSION >
WESTERLY MID LEVEL FLOW WITH SFC HIGH PRESSURE BUILDING EAST ACROSS 
THE REGION. 12Z ILN SOUNDING CONTINUES TO SHOW SHALLOW LOW LEVEL 
MOISTURE TRAPPED BELOW AN INVERSION AROUND 880 MB. WITH SFC HIGH 
PRESSURE AND WEAK FLOW...EXPECT THAT CLOUDS WILL HANG ON OVERNIGHT.
THERE MAY BE SOME BREAKS ACRS THE FAR SRN COUNTIES BUT OTHERWISE 
EXPECT MAINLY CLOUDY SKY CONDITIONS. TEMPERATURES WILL BE CLOSE TO 
NORMAL WITH LOWS FROM THE MID 20S NORTH TO THE UPPER 20S SOUTH.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/...
MID LEVEL S/W RIDGE PASSES EAST WITH FLOW BACKING AHD OF SRN
SYSTEM. SFC HIGH PRESSURE TO REMAIN IN CONTROL OF OUR WEATHER WITH
SFC TROF AND DEEP MOISTURE STAYING TO OUR SOUTH ON SATURDAY. MODEL
TRENDS HAVE BEEN CONSISTENT IN KEEPING PRECIPITATION SOUTH OF ILN/S
FA. THEREFORE WILL CONTINUE A DRY FCST FOR SATURDAY. ALTHOUGH LOW
CLOUDS MAY IMPROVE EXPECT AN INCREASE IN MID/HI LEVEL CLOUDS.
HIGHS ON SATURDAY LOOK TO BE A LITTLE BELOW NORMAL...RANGING FROM
THE MID 30S NORTH TO NEAR 40 SOUTH.

MID LEVEL FLOW AGAIN BECOMES WESTERLY WITH SFC HIGH PRESSURE 
BUILDING EAST ACRS THE OHIO VALLEY SATURDAY NIGHT/SUNDAY. EXPECT AN 
INCREASE IN WAA CLOUDS OVERNIGHT SATURDAY INTO SUNDAY. LOWS SATURDAY 
NIGHT TO RANGE FROM THE MID 20S NORTH TO THE UPPER 20S SOUTH. 

UNDER THE INFLUENCE OF WAA BUT CONTINUED CLOUD COVER...TEMPERATURES 
LOOK TO BE ONLY SLIGHTLY WARMER SUNDAY. EXPECT HIGHS TO RANGE FROM 
THE UPPER 30S NORTH TO THE LOWER/MID 40S SOUTH.

IN SPLIT FLOW REGIME THE MID LEVEL FLOW BACKS SUNDAY NIGHT. 
NUMERICAL MODEL SOLNS HAVE TRENDED SLOWER WITH THE ONSET OF 
PRECIPITATION FROM THE SOUTH. THEREFORE WILL KEEP SUNDAY NIGHT DRY. 
IN WAA REGIME WITH AN INCREASE IN CLOUDS AND WIND...LOWS LOOK TO BE 
ABOVE NORMAL. SUNDAY NIGHTS LOWS FORECAST TO RANGE FROM THE UPPER 
20S NORTH TO THE MID 30S SOUTH.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
SOUTHERLY FLOW AHEAD OF LOW PRESSURE IN THE NORTHERN PLAINS WILL 
RESULT IN INCREASING MOISTURE ACROSS THE REGION ON MONDAY. THE 
MOISTURE AND LIFT SHOULD RESULT IN SOME RAIN BY MONDAY AFTERNOON. 
THE CHANCE OF RAIN WILL CONTINUE INTO TUESDAY AS A COLD FRONT 
APPROACHES FROM THE WEST.

THE COLD FRONT SHOULD PASS THROUGH THE AREA TUESDAY NIGHT AND 
WEDNESDAY MORNING. THE 12Z GFS SHOWS A FASTER PROGRESSION OF THE 
FRONT...WHILE THE 12Z ECMWF INDICATES SURFACE LOW PRESSURE 
DEVELOPING ALONG THE FRONT AND SLOWING EASTWARD PROGRESSION OF THE 
SYSTEM. THIS FORECAST PACKAGE LEANS TOWARD THE ECMWF SOLUTION AS 
PREVIOUS RUNS OF THE GFS HAVE ALSO HINTED AT THE DEVELOPMENT OF A 
SURFACE WAVE. RAIN SHOULD ACCOMPANY THE FRONT...WITH A CHANGEOVER TO 
SNOW FROM WEST TO EAST WEDNESDAY MORNING AS COLDER AIR ARRIVES.

WINDY CONDITIONS WILL FOLLOW THE FRONT AND REMAIN IN PLACE FROM 
WEDNESDAY AFTERNOON THROUGH THURSDAY. THERE WILL ALSO BE SNOW 
SHOWERS ACROSS THE AREA DURING THIS TIME. DRYING IS EXPECTED BY 
LATER THURSDAY AND THURSDAY NIGHT...ALTHOUGH ANOTHER SYSTEM IS 
PROGGED TO DEVELOP IN THE MID MISSISSIPPI VALLEY THAT MAY BRING SOME 
LIGHT PRECIPITATION BACK TO THE AREA FRIDAY.

&&

.AVIATION /05Z SATURDAY THROUGH WEDNESDAY/...
MVFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. CIGS WILL
GENERALLY BE MVFR THROUGH THE TAF PERIOD WITH SOME MVFR VSBYS ALSO
POSSIBLE OVERNIGHT AND INTO THE EARLY DAYTIME HOURS ON SATURDAY.
AN AREA OF LIGHT SNOW JUST SOUTHWEST OF THE AREA WILL SLOWLY
DISSIPATE AS IT APPROACHES THE TAF SITES. CURRENT INDICATIONS ARE
THAT SOME VERY LIGHT SNOW WILL BE POSSIBLE AT KCVG AND KLUK BEFORE
DISSIPATING. WINDS WILL BE LIGHT AND LESS THAN 10 KNOTS THROUGH
THE TAF PERIOD.

OUTLOOK...MVFR CEILINGS MAY CONTINUE THROUGH SATURDAY NIGHT. MVFR
CEILINGS POSSIBLE MONDAY. MVFR/IFR CEILINGS AND VISIBILITIES ARE
POSSIBLE TUESDAY INTO WEDNESDAY...ALONG WITH PRECIPITATION AND
WINDY CONDITIONS.

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.

&&

$$
SYNOPSIS...AR
NEAR TERM...HATZOS/AR
SHORT TERM...AR
LONG TERM...SHOBE2
AVIATION...NOVAK




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