FXUS61 KILN 220533
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
1233 AM EST TUE DEC 22 2009
.SYNOPSIS...
SURFACE HIGH PRESSURE WILL STAY OVER THE OHIO VALLEY TONIGHT AND
SLIDE NORTHEAST ON WEDNESDAY. EAST WINDS OVER THE OHIO VALLEY WILL
BE FOUND AHEAD OF A LOW PRESSURE SYSTEM THAT IS GATHERING STRENGTH
IN THE SOUTHERN PLAINS ON WEDNESDAY. THIS LOW WILL EJECT TO THE
MIDWEST ON THURSDAY...AND THE NEXT SHOT OF PRECIPITATION WILL
OCCUR THURSDAY NIGHT AS THE UPPER LEVEL RIDGE CROSSES TO THE EAST.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
SATELLITE IMAGERY SHOWS LOW CLOUDS REMAIN ACROSS THE REGION.
EXPECT THIS TO CONTINUE THROUGH THE NIGHT. LIGHT SNOW IN THE UPPER
MIDWEST COULD WORK ITS WAY INTO THE FAR NORTHWEST ZONES BEFORE
DAYBREAK. SO ADDED SLIGHT CHANCE POPS THERE. BUMPED UP LOWS
SLIGHTLY DUE TO PERSISTENT LOW CLOUDS.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
CONVERGENT UPPER LEVEL FLOW WILL COMBINE WITH SOME EMBEDDED SHORT
WAVES TO INCREASE MOISTURE FROM THE MIDDLE LEVELS OF THE
ATMOSPHERE DOWNWARDS. SURFACE HIGH PRESSURE CENTERED OVER CWA AT
DAYBREAK TUES WILL MOVE NORTHEAST AS THE COLUMN TRIES TO
PRECIPITATE. HAVE INCLUDED THE CHANCE FOR SNOW IN THE NORTHERN TWO
THIRDS OF FCST AREA...INCREASING FROM THE NORTHWEST. BY THE
EVENING THE HIGH SHOULD HAVE MOVED NORTHEAST AND A RIDGE OF HIGH
PRESSURE IN THE MID LEVELS OF THE ATMOSPHERE WILL HAVE SHUNTED THE
CONVERGENT LAYER TO THE NORTH-NORTHEAST. WITH RISING HEIGHTS...I
LOWERED THE TEMPERATURES ABOUT TWO DEGREES IN KENTUCKY COUNTIES
DURING THE DAY.
EAST WINDS KEEP A HOLD ON THE OHIO VALLEY AS THE LOW IN THE
SOUTHERN PLAINS SPINS INTO THE MIDWEST AND TRACKS NORTH. THEY WILL
PICK UP DURING THE DAY WEDNESDAY AND HELP USHER IN DRIER AIR
OVERNIGHT...PARTICULARLY EAST OF METRO COLUMBUS. CLOUD COVER AND
CONTINUED MOISTENING IN THE WEST WILL LIMIT THE DRYING EFFECT OF
EAST WINDS HERE BUT MAV GUIDANCE WAS SHOWING A STRONG DROP IN
DEWPOINTS AND SIGNIFICANTLY COLDER AIR WED NIGHT IN THE FAR
NORTHEASTERN CWA. TRENDED IN THIS DIRECTION AND SPLIT OUT THE
LANCASTER SUB GROUP FROM CENTRAL OHIO TO INDICATE THE DRYING AND
COOLER OVERNIGHT LOWS.
AS THE COLUMN MOISTENS FROM THE CLOSING PROXIMITY OF THE MIDWEST
LOW ON WED NIGHT...HAVE INTRODUCED VERY LOW CHANCE OF
PRECIP...MORESO IN THE WEST. RAN PTYPE OFF OF THE SURFACE TEMPS
AND INDICATED FREEZING/NON FREEZING RAIN BETWEEN 30 AND 33
DEGREES. LOWER WAS FREEZING AND HIGHER WAS PLAIN RAIN. TREND IS
FOR WARMING AS WINDS TURN SOUTHEAST AND SOUTH BEYOND THIS FORECAST
PERIOD SO I DOUBT THAT ZR WILL PREVAIL FOR ANY PERIOD OF TIME IF
IT OCCURS.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
GUIDANCE CONTINUES TO SHOW A DEEP SFC LOW KICKING OUT OF THE MS VLY
INTO THE WRN LAKES DURING THE FIRST PART OF THE PERIOD. THERE IS
STILL SOME RUN TO RUN DIFFERENCES...PUT AT LEAST THE GENERAL PATTERN
IS STABLE.
PERIOD BEGINS WITH H5 LOW DIGGING THRU THE SRN PLAINS. IN
RESPONSE...SFC LOW HAD MOVED INTO CNTRL PLAINS. WEAK WRMFNT EXTENDED
E INTO KY AND PROVIDES SOME LIFT...HOWEVER THE MODELS WERE KEEPING
THE BETTER LIFT AND QPF FARTHER W AT 12Z THU. KEPT A LOW CHANCE OF
PCPN MAINLY IN THE W AT 12Z THU. TEMPERATURES AT THAT TIME ARE
EXPECTED TO BE BELOW FREEZING ACRS THE NRN COUNTIES...SO WILL CARRY
A MENTION OF FZRA...BUT IT IS ONLY A SLGT CHC.
H5 LOW LIFTS OUT INTO THE CNTRL PLAINS ON THU AND OCCLUDED FNT
PUSHES E INTO THE LOWER OH VLY. CHC OF PCPN INCREASES DURING THE DAY
FROM W TO E. SURGE OF WRM AIR AHEAD OF LOW WILL TURN ALL PCPN
TO RAIN THU AFTN...ENDING ANY CHANCE OF FZRA AS THICKNESSES
SUPPORT ALL RAIN.
BEST POPS STILL LOOK LIKE CHRISTMAS EVE NIGHT AS LIFT INCREASES ON
THU AHEAD OF FNT. LOOKS LIKE SANTA WILL HAVE TO PUT THE ROOF UP ON
THE SLEIGH TO STAY DRY. SFC LOW IS SLOWER TO KICK OUT THRU THE
LAKES...SO ALTHOUGH FROPA IS STILL EXPECTED EARLY CHRISTMAS
DAY...THE CAA WILL BE SLOW AND ANY POST FRONT PCPN WILL PROBABLY
FALL AS RAIN. CRITICAL THICKNESSES FALL FRI NGT AND CHANGING THE RA
BACK TO SN.
CYCLONIC FLOW ON BACK SIDE OF LOW WILL LINGER FOR THE WEEKEND
PROVIDING CHC OF SNOW SHOWERS. HIGH PRESSURE FINALLY TRIES TO BUILD
IN ON MONDAY. THE GFS IS A LITTLE QUICKER THAN THE ECMWF WITH
THIS...SO LINGERED A 20 POP OF SNOW SHOWER ON MONDAY.
RAN CLOSE TO EXTENDED GFS MOS FOR TEMPS.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
MVFR CIGS AND VSBYS EXPECTED TO PERSIST THROUGH DAYBREAK.
WEAKENING SYSTEM APPROACHING FROM THE NORTHWEST MAY SPREAD A FEW
SNOW SHOWERS OR FLURRIES INTO THE AREA LATER THIS MORNING. THE BEST
CHANCE FOR THIS APPEARS TO BE ACROSS THE NORTH WHERE WILL ALLOW
FOR A VCSH. AS LOW LEVEL FLOW BECOMES MORE SOUTHERLY ACROSS THE
SOUTH...WE COULD SEE SOME BREAKS DEVELOP IN THE LOWER CLOUDS AS WE
HEAD THROUGH THE DAY AT KCVG/KLUK. ELSEWHERE...EXPECT LOW LEVEL
EASTERLY FLOW TO ALLOW MVFR CIGS TO CONTINUE THROUGH THE REST OF
THE TAF PERIOD.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES EXPECTED THURSDAY NIGHT
INTO FRIDAY WITH PERIODS OF IFR CEILINGS AND VISIBILITIES
POSSIBLE. MVFR CEILINGS WILL LIKELY PERSIST THROUGH SATURDAY WITH
MVFR VISIBILITIES POSSIBLE.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...FRANKS
NEAR TERM...
SHORT TERM...FRANKS
LONG TERM...SITES
AVIATION...JGL
