FXUS61 KILN 012329
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
629 PM EST TUE DEC 1 2009
.SYNOPSIS...
A CLOSED UPPER LOW OVER TEXAS WILL MERGE WITH A DEEPENING UPPER
TROUGH OVER THE CENTRAL PLAINS ON WEDNESDAY...RESULTING IN SURFACE
CYCLOGENESIS OVER THE OHIO VALLEY. THE SURFACE LOW IS EXPECTED TO
TRACK INTO CENTRAL OR WESTERN OHIO BY LATE WEDNESDAY
AFTERNOON...AND INTO NEW ENGLAND BY EARLY THURSDAY.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
HIGH CLOUDS WILL SLOWLY INCREASE FROM THE SOUTH OVERNIGHT AS
CLOSED UPPER LOW OVER TEXAS MOVES NORTHEAST INTO THE GULF STATES.
CLOUDS WILL INITIALLY ENCOUNTER UPPER RIDGING OVER THE OHIO VALLEY
AND WILL BE SLOW TO SPREAD NORTH THIS EVENING...BUT WILL GRADUALLY
THICKEN OVERNIGHT AS RIDGE MOVES EASTWARD. TRENDED NEAR MOS
CONSENSUS FOR TEMPS ACROSS THE SOUTH...AND A FEW DEGREES BELOW
GUIDANCE ACROSS THE NORTH WHERE SKIES WILL STAY MOSTLY CLEAR FOR
MOST OF THE NIGHT.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
DEEPENING SURFACE LOW WILL TRACK INTO THE TENNESSEE VALLEY DURING
THE DAY WEDNESDAY...AND INTO CENTRAL OR EASTERN PORTIONS OF THE
OHIO VALLEY BY WEDS EVE. EXACT TRACK OF THE LOW REMAINS FAIRLY
UNCERTAIN WITH THE GUIDANCE ENVELOPE RANGING ANYWHERE FROM
CENTRAL INDIANA TO WESTERN WEST VIRGINIA. GIVEN THE WESTWARD BIAS
THESE DEEPENING SW FLOW SYSTEMS TEND TO HAVE...PREFERRED A BLEND
OF THE 12Z NAM AND 09Z SREF MEAN...WHICH WOULD TAKE SFC LOW NEAR A
CINCINNATI-BELLEFONTAINE TRACK BTWN 00Z AND 03Z THURS. COLDEST AIR
WILL REMAIN WELL TO THE WEST OF THE LOW...SO REGARDLESS OF LOW
TRACK...CHANCES FOR WIDESPREAD RAIN EVENT ACROSS ILN CWA ARE HIGH
AND CHANCES FOR ACCUMULATING SNOW ARE LOW.
RAIN WILL BE QUICK TO OVERSPREAD AREAS ALONG AND SOUTH OF THE OHIO
RIVER WEDS MORNING AS LOW LEVEL WARM FRONT AND DEEP ISENTROPIC
LIFT SPREAD INTO NORTHERN KENTUCKY AND SOUTHERN OHIO. RAINFALL
RATES ACROSS THE SE CWA MAY BE ENHANCED BY DEEPENING LOW LEVEL
CONVERGENCE AHEAD OF A STRENGTHENING 50-60 KT LLJ...BUT DO NOT
EXPECT ANY SUBSTANTIAL HIGH WATER PROBLEMS. WIDESPREAD BAND OF
RAIN WILL STEADILY LIFT NORTH ACROSS THE CWA THROUGH THE AFTERNOON
AND LIFT TO NORTHERN PARTS OF THE CWA BY EARLY EVENING AS SFC LOW
TRACKS INTO NORTHERN KY. LOW WILL TRACK NE WEDS EVE AND SHOULD
TRACK SOMEWHERE BETWEEN COLUMBUS AND MUNCIE...WHICH WILL SHIFT
MOST WIDESPREAD PRECIP NORTH OF THE CWA. HOWEVER...STILL EXPECT
SCATTERED SHOWERS ACROSS MUCH OF THE AREA THROUGH THE EVENING AS
UPPER TROUGH INTERACTS WITH STRONG LOW LEVEL COLD AIR ADVECTION.
MAY SEE SOME CHANGEOVER TO -SN ACROSS THE NORTHWEST HALF OF THE
CWA LATE WEDS AS COLDER AIR FILTERS IN. HOWEVER...PRECIP AMOUNTS
WILL BE VERY LIGHT AND TEMPS TEMPS SHOULD REMAIN ABOVE FREEZING
WHICH WILL MAKE ANY SNOW ACCUM UNLIKELY.
COLD AIR ADVECTION AND THICK LOW LEVEL MOISTURE WILL MAKE IT
DIFFICULT FOR TEMPS TO RISE MUCH AT ALL ON THURS. MIDLEVELS WILL
DRY OUT SIGNIFICANTLY BY THURS AFTERNOON...SO ANY LINGERING PRECIP
WILL LIKELY TAKE THE FORM OF LIGHT DRIZZLE. SURFACE RIDGING WILL
THEN BUILD IN FROM THE SOUTHWEST THURS NIGHT AND WILL ALLOW LOW
LEVEL CLOUDS TO BEGIN TO BREAK UP BY EARLY FRIDAY MORNING.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
WILL START THE EXTENDED PERIOD IN STRONG COLD ADVECTION...LEADING TO
AN UNDERCUTTING OF GUIDANCE FOR HIGHS AND LOWS THROUGH THE FIRST FEW
FORECAST PERIODS.
HAVE OPTED FOR A SOMEWHAT UNCERTAIN DRY EXTENDED FORECAST AT THIS
TIME...WITH A FEW CLOSE CALLS...BUT NONE WITH POTENTIAL FOR ANY
SIGNIFICANT IMPACT. TIMING AND PLACEMENT DIFFERENCES ON A FEW OF
THESE SUBTLE FEATURES...FROM RUN TO RUN AND MODEL TO MODEL...HAVE
PRECLUDED THE INCLUSION OF PRECIPITATION FOR NOW.
ON FRIDAY NIGHT INTO SATURDAY...A 500MB TROUGH WILL SWING INTO THE
OHIO VALLEY. THERE WILL BE PLENTY OF MOISTURE AHEAD OF IT MOVING UP
THE APPALACHIANS...BUT AT THIS TIME IT LOOKS TO STAY EAST OF THE
FORECAST AREA. WITH THE SHORTWAVE ITSELF MOVING THROUGH...FLURRIES
OR LIGHT SNOW SHOWERS CANNOT BE TOTALLY RULED OUT FOR THE FORECAST
AREA...BUT MOISTURE LOOKS PRETTY MEAGER AT THIS POINT.
ON MONDAY THERE WILL BE SOME WEAK LIFT ACROSS NORTHERN OHIO...WITH
MOISTURE STREAMING IN FROM THE WEST. THIS ALSO LOOKS TO HANG JUST
OUTSIDE THE BORDERS OF THE ILN FORECAST AREA.
TEMPERATURES WILL BOTTOM OUT FRIDAY AND SATURDAY NIGHT. ON
SUNDAY...A SLOW BUT STEADY MODERATION WILL BEGIN IN SOUTHERLY FLOW.
TEMPS ARE NEAR MEX GUIDANCE FOR THE TAIL END OF THE EXTENDED.
&&
.AVIATION /23Z TUESDAY THROUGH SUNDAY/...
A DYNAMIC AND MOISTURE LADEN LOW PRESSURE SYSTEM WILL MOVE FROM
THE LOWER GULF COAST STATES TO THE OHIO RIVER VALLEY BY 00Z
THURSDAY...THEN NE TOWARD THE NEW ENGLAND REGION BY 12Z THURSDAY.
VFR CONDITIONS CAN BE EXPECTED THROUGH 12Z. GRADUAL DETERIORATING
CIGS AND VSBYS CAN BE EXPECTED BETWEEN 12Z WEDNESDAY AND 00Z
THURSDAY AS WIDESPREAD RAIN OVERSPREADS THE TAF SITES FROM SOUTH TO
NORTH. CIGS ARE FORECAST TO DROP INTO THE IFR RANGE AS WELL AS
VSBYS AS SFC LOW PRESSURE MOVES ACRS THE FORECAST AREA.
OUTLOOK...MVFR/IFR CIGS/VSBYS LIKELY WEDNESDAY NIGHT. MVFR/IFR
CIGS TO CONTINUE ON THURSDAY. MVFR CIGS POSSIBLE ON FRIDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HAWBLITZEL
NEAR TERM...HAWBLITZEL
SHORT TERM...HAWBLITZEL
LONG TERM...HATZOS
AVIATION...HICKMAN
