FXUS61 KILN 221129
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
629 AM 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/...
WEAK ISENTROPIC LIFT IS RESULTING IN AN AREA OF LIGHT SNOW
EXTENDING FROM NEAR MSP INTO NORTHERN ILLINOIS AND WESTERN
INDIANA. ISENTROPIC LIFT WILL WEAKEN AS IT ENCOUNTERS HIGH
PRESSURE FURTHER EAST...AND PRECIP WILL HAVE A DIFFICULT TIME
MAKING IT INTO EASTERN INDIANA AND OHIO. SEEING SOME WEAK RETURNS
ON KILN RADAR WHICH ARE UNLIKELY TO BE HITTING THE GROUND.
HOWEVER...A FEW HOURS OF LIGHT SNOW ALOFT MAY BE ENOUGH TO
SATURATE LOWER LEVELS TO SQUEEZE OUT A FEW LIGHT SNOW SHOWERS OR
FLURRIES AT THE GROUND...ESPECIALLY ACROSS THE NORTHWEST HALF OF
THE CWA. CONTINUED SLIGHT CHANCE OR LOW CHANCE POPS...MAINLY THIS
MORNING. BACK EDGE OF LOW CLOUDS IS MOVING NORTHWARD INTO CENTRAL
KENTUCKY...AND SOUTHERN PORTIONS OF THE CWA WILL LIKELY SEE
THINNING CLOUDS LATER TODAY. THIS WILL ALLOW TEMPS TO RISE INTO
THE UPPER 30S AND LOW 40S ACROSS THAT AREA...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 MONDAY/...
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 /12Z TUESDAY THROUGH SATURDAY/...
SHORT WAVE ENERGY PUSHING ACROSS THE UPPER MISSISSIPPI VALLEY
HELPING TO PRODUCE AN AREA OF LIGHT SNOW FROM NORTHERN ILLINOIS
ACROSS NORTHERN INDIANA AND INTO NORTHWEST OHIO THIS MORNING. THE
SHORT WAVE IS FORECAST TO WEAKEN AS IT CONTINUES TO PUSH EAST BUT
WE MAY STILL SEE A FEW SNOW SHOWERS SNEAK DOWN INTO THE NORTHERN
TAFS THROUGH LATE MORNING AND WILL HANDLE THREAT WITH A VCSH. CIGS
HAVE BEEN IMPROVING SOMEWHAT ALONG THE LEADING EDGE OF THIS PCPN
BUT GENERALLY THINK MVFR CIGS WILL PERSIST THROUGH THE DAY ACROSS
THE NORTH. MID LEVEL RIDGING WILL BEGIN TO WORK ITS WAY IN FROM
THE SOUTHWEST THROUGH THE AFTERNOON AND INTO TONIGHT. THIS SHOULD
LEAD TO CIGS IMPROVING TO VFR ACROSS OUR SOUTHWEST LATER THIS
AFTERNOON AND THEN ACROSS THE REMAINDER OF THE AREA OVERNIGHT.
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...HAWBLITZEL
NEAR TERM...HAWBLITZEL
SHORT TERM...HAWBLITZEL
LONG TERM...SITES
AVIATION...JGL
