FXUS61 KILN 221810
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
110 PM EST TUE DEC 22 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE OHIO VALLEY WILL SLIDE EAST THIS
MORNING...WHILE A WEAK UPPER SHORTWAVE SKIRTS THE GREAT LAKES.
UPPER RIDGING WILL BUILD INTO THE REGION ON WEDNESDAY. A STRONG
UPPER TROUGH WILL DIG INTO THE CENTRAL U.S. ON THURSDAY AND MOVE
INTO THE OHIO VALLEY AND GREAT LAKES LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A WEAK S/WV COMBINED WITH A QUICK SHOT OF ISENTROPIC LIFT AS SEEN
BETWEEN THE 290-295 K LAYER WILL RESULT IN A PERIOD OF LIGHT SNOW
FOR MOST LOCATIONS ALONG AND NORTH OF THE OHIO RIVER THROUGH EARLY
AFTERNOON. SNOW WILL TAPER OFF BY MID AFTERNOON AS S/WV MOVES OFF
TO THE EAST AND ISENTROPIC LIFT WEAKENS. SNOW ACCUMULATIONS ARE
EXPECTED TO BE AN INCH OR LESS WITH THE HIGHEST AMOUNTS IN THE
WHITEWATER/MIAMI/WEST CENTRAL OHIO AREAS.
AFTERNOON TEMPS ARE FORECAST TO RISE INTO THE UPPER 30S AND LOW
40S ACROSS THE SOUTH...WITH TEMPS IN THE MID 30S ELSEWHERE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
EXPECT CLOUDS TO DECREASE FROM SOUTH TO NORTH TONIGHT AS MIDLEVEL
RIDGING BEGINS TO BUILD INTO THE OHIO VALLEY. THIS WILL KEEP SKIES
PARTLY CLOUDY ON WEDNESDAY. GUIDANCE IS IN GOOD AGREEMENT ON TEMPS
TONIGHT AND WEDS...AND DID NOT MAKE ANY SIGNIFICANT DEVIATIONS
FROM THESE NUMBERS.
MAIN FOCUS THIS PERIOD IS ON A DEEPENING UPPER LOW OVER THE
CENTRAL PLAINS WHICH WILL SLOWLY MOVE INTO THE OHIO VALLEY THROUGH
FRIDAY. AS LOW- AND MID-LEVEL RIDGING PUSHES EAST OF THE REGION
WEDNESDAY NIGHT...A SLOW RETURN OF ELEVATED THETA-E WILL PUSH INTO
SOUTHWESTERN PORTIONS OF THE CWA. THIS MAY RESULT IN SOME WEAK
ISENTROPIC LIFT AND THE POSSIBILITY OF LIGHT PRECIPITATION MOVING
INTO WESTERN AND SOUTHWESTERN PORTIONS OF THE CWA WEDNESDAY
EVENING AND OVERNIGHT. HOWEVER...THE BEST LIFT WILL REMAIN WELL TO
THE WEST OF THE AREA THROUGH THIS TIME...AND STEADY EASTERLY FLOW
AT THE SURFACE WILL INHIBIT SIGNIFICANT MOISTENING OF THE LOW
LEVELS. THEREFORE...ANY PRECIP WHICH DOES DEVELOP SHOULD BE VERY
LIGHT. LOW LEVEL WETBULB PROFILES WEDNESDAY NIGHT SUPPORT A MIX OF
SNOW...SLEET AND FREEZING RAIN IN THE EVENING WHICH WOULD
TRANSITION TO PURE FREEZING RAIN FROM SOUTH TO NORTH AFTER
MIDNIGHT AND INTO THURSDAY MORNING. WHILE ANY PRECIP AMOUNTS WOULD
ONLY BE A FEW HUNDREDTHS OF AN INCH AT BEST...ANY FREEZING RAIN AT
ALL COULD BE ENOUGH TO CAUSE A VERY LIGHT GLAZE AND CAUSE A FEW
TRAVEL PROBLEMS ON THE MORNING OF A BUSY TRAVEL DAY. WILL KEEP AN
EYE ON THIS SITUATION...BUT WITH MODELS CONTINUING TO TREND WEAKER
AND FURTHER WEST WITH THE LIFT THURSDAY MORNING...THE CHANCE OF
SIGNIFICANT TRAVEL PROBLEMS WEDS NIGHT AND THURS MORNING APPEARS
TO BE DECREASING.
TEMPS WILL STEADILY WARM ON THURSDAY WHICH WOULD CAUSE ANY PRECIP
TO TRANSITION FROM FREEZING RAIN TO RAIN FROM SOUTH TO NORTH
THROUGH THE LATE MORNING AND AFTERNOON. AGAIN...BEST DYNAMICS AND
RAIN CHANCES WILL REMAIN WELL TO THE WEST OF THE CWA THROUGH EARLY
THURSDAY AFTERNOON...SO ANY PRECIP AMOUNTS THROUGH THIS TIME WILL
BE LIGHT IF ANYTHING. UPPER LOW WILL BEGIN TO SHIFT EAST THURSDAY
NIGHT...CAUSING A STRONG LOW LEVEL JET AND SURGE OF MOISTURE TO
MOVE IN FROM THE WEST. WILL SEE PRECIP INCREASING FROM WEST TO
EAST BY LATE THURSDAY AFTERNOON...WITH WIDESPREAD RAIN EXPECTED
ACROSS THE AREA THURSDAY NIGHT. LOW LEVEL CONVERGENCE AND STRONG
SURGE OF DEEP MOISTURE...PRECIP H20 VALUES APPROACHING ONE
INCH...WILL SUPPORT WIDESPREAD RAINFALL WHICH MAY EXCEED A HALF
INCH. HOWEVER THE PROGRESSIVE NATURE OF THE SYSTEM BY THE TIME IT
MAKES IT INTO THE OHIO VALLEY SHOULD PREVENT A SIGNIFICANT FLOODING
THREAT THURSDAY NIGHT.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
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 /18Z TUESDAY THROUGH SUNDAY/...
AN UPR LVL DISTURBANCE CURRENTLY OVER THE AREA WILL MOVE TO THE
EAST OVER THE NEXT SEVERAL HOURS. WEAK WAA IN ASSOCIATION WITH THE
DISTURBANCE WILL WEAKEN TOO...AND THUS...LIGHT SNOW SHOULD COME TO
AN END BETWEEN 20Z AND 23Z.
A MID LVL RIDGE IS FORECAST TO BUILD EASTWARD INTO THE MIDDLE OHIO
VALLEY THROUGH THE TAF PERIOD. MODELS INDICATE THAT LOW LEVEL
MOISTURE MAY REMAIN TRAPPED UNDERNEATH AN INVERSION. ATTM...IT IS
NOT TOTALLY CLEAR HOW LONG THE MOISTURE WILL LAST...ESPECIALLY
ACRS SRN TAF SITES...SUCH AS KCVG AND KLUK. HAVE KEPT CIGS
PESSIMISTIC FOR POINTS TO THE NORTH...GENERALLY AROUND 1500 FEET.
ENOUGH HEATING AND MIXING SHOULD RESULT IN VFR CIGS ON WEDNESDAY.
WITH ADDED SFC MOISTURE FROM TODAYS PCPN...VSBYS WILL FLUCTUATION
BETWEEN VFR AND MVFR THROUGH 15Z THURSDAY.
OUTLOOK...MVFR CEILINGS AND VISIBILITIES EXPECTED THURSDAY NIGHT
INTO FRIDAY WITH PERIODS OF IFR CEILINGS AND VISIBILITIES
POSSIBLE. MVFR CEILINGS WILL LIKELY PERSIST THROUGH SUNDAY WITH
MVFR VISIBILITIES POSSIBLE.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HAWBLITZEL
NEAR TERM...HICKMAN
SHORT TERM...HAWBLITZEL
LONG TERM...SITES
AVIATION...HICKMAN
