FXUS61 KILN 240820
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
320 AM EST THU DEC 24 2009
.SYNOPSIS...
A DEEP SURFACE LOW WILL OCCLUDE OVER THE OZARKS TODAY...AS A
STRONG UPPER TROUGH DIGS INTO THE SOUTHERN AND CENTRAL PLAINS. THE
SURFACE LOW WILL MEANDER NORTHWARD INTO IOWA THROUGH FRIDAY
NIGHT...SENDING AN OCCLUDED FRONT INTO THE OHIO VALLEY BY EARLY
FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPPER RIDGE IS PUSHING OFF TO THE EAST...ALLOWING FOR A
STRENGTHENING LOW LEVEL JET TO PUSH INTO THE LOWER OHIO VALLEY
THIS MORNING. STRONGEST LOW LEVEL WINDS WILL REMAIN WEST OF THE
AREA TODAY...BUT ENOUGH FLOW WILL EXIST NORMAL TO THETA GRADIENT
TO BRING INCREASING ISENTROPIC LIFT THROUGH THE DAY. LOW LEVELS
ARE QUITE DRY...ESPECIALLY ACROSS THE EASTERN CWA. HOWEVER...MODELS
HAVE BEEN STRUGGLING WITH THE EXTENT OF LOW-LEVEL SATURATION IN THESE
STEADY ISENTROPIC LIFT SCENARIOS...AND THINK THEY ARE TOO SLOW
BRINGING PRECIP INTO THE CWA TODAY. WHILE ANY PRECIP WILL BE VERY
LIGHT...STILL THINK THERE IS ENOUGH LIFT TO WARRANT SLIGHT CHANCE
OR LOW CHANCE POPS ACROSS THE WESTERN HALF OF THE CWA THROUGH
EARLY AFTERNOON. SURFACE SHOULD WARM ABOVE FREEZING BEFORE ANY
PRECIP ARRIVES...SO THREAT FOR FREEZING RAIN IS DIMINISHING.
HOWEVER...LOW LEVEL WETBULB VALUES WILL STILL BE NEAR OR BELOW
FREEZING...SO LIGHT SLEET IS A POSSIBILITY IF ANY PRECIP MAKES IT
THIS FAR EAST THIS MORNING. NOSE OF LOW LEVEL JET WILL NUDGE INTO
THE SOUTHWEST CWA LATE THIS AFTERNOON...WITH LARGE AREA OF RAIN
APPROACHING SOUTHEAST INDIANA AND NORTHERN KENTUCKY BY EARLY
EVENING.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
SURFACE LOW TRACKS NORTH TO NEAR ST LOUIS OVERNIGHT...WITH STRONG
LOW LEVEL FIELD SPREADING NORTHWARD TO THE EAST OF THE LOW. STRONG
CONVERGENCE AND ISENTROPIC LIFT WILL ALLOW FOR A WIDESPREAD AREA OF
RAIN WHICH WILL OVERSPREAD THE ENTIRE CWA FROM SOUTHWEST TO
NORTHEAST OVERNIGHT THURSDAY AND EARLY FRIDAY. 850 HPA-WINDS WILL
BE VERY STRONG...POTENTIALLY IN EXCESS OF 75-KT...BUT LOW LEVEL
INVERSION WILL BE MUCH TOO STRONG TO ALLOW ANY SIGNIFICANT
MOMENTUM TRANSFER TO THE GROUND. STILL...WITH VERY TIGHT GRADIENT
IN PLACE AND WINDS UP TO 60-KT AT 925 HPA...EXPECT A STIFF EAST-
SOUTHEAST WIND THURSDAY NIGHT AND FRIDAY MORNING WITH GUSTS UP TO
40 MPH POSSIBLE AT TIMES.
OCCLUDED FRONT WILL LIFT NORTHEAST ACROSS THE CWA FRIDAY
MORNING...BRINGING AN END TO THE WIDESPREAD RAIN ACROSS THE
SOUTHWEST BY MID FRIDAY MORNING...AND ACROSS CENTRAL OHIO BY EARLY
AFTERNOON. WILL STILL BE PLENTY OF LOW LEVEL MOISTURE BEHIND THE
FRONT...AND WITH WEAK LOW LEVEL CONVERGENCE IN PLACE...EXPECT
SCATTERED RAIN SHOWERS TO PERSIST THROUGH FRIDAY AFTERNOON. COLD
AIR ADVECTION DOES NOT GET GOING UNTIL EARLY FRIDAY EVENING...SO
ANY CHANGE OVER TO SNOW WILL NOT OCCUR UNTIL AFTER DARK FRIDAY.
LITTLE IF ANY SNOW ACCUMULATION WILL OCCUR WITH THIS ACTIVITY.
LINGERING LOW LEVEL MOISTURE AND UPPER LOW MOVING IN FROM THE WEST
WILL MAINTAIN A CHANCE FOR SCATTERED SNOW SHOWERS SATURDAY AND
SATURDAY NIGHT...WITH ANY ACCUMULATION LIMITED TO A HALF INCH OR
LESS.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
THERE WILL BE A CHANCE OF SNOW SHOWERS SUNDAY AND MONDAY AS THE
UPPER LOW TRAVELS THROUGH THE WESTERN GREAT LAKES TO OHIO. IT
APPEARS THAT THE FETCH OFF LAKE MICHIGAN WILL BE FAVORABLE FOR
ENHANCEMENT OF THE SNOW SHOWERS ON MONDAY...ESPECIALLY OVER
NORTHERN COUNTIES. HIGH PRESSURE WILL PROVIDE DRY CONDITIONS AS IT
MOVES ACROSS THE REGION ON TUESDAY AND WEDNESDAY.
COLD WEATHER WILL PERSIST THROUGH THE PERIOD AND WE MAY NOT SEE
TEMPERATURES REACH NORMAL VALUES AT ALL. HIGHS ARE FORECAST TO BE IN
THE 20S AND 30S.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
CLEAR SKIES CURRENTLY ACROSS EASTERN PORTIONS OF OUR FA BUT AN AC
DECK IS TRYING TO SPREAD BACK IN FROM THE SOUTHWEST. MODELS ARE
INDICATING THAT THESE MID CLOUDS MAY HAVE A TOUGH TIME MAKING IT
MUCH FARTHER EAST AS THEY ENCOUNTER A DRIER AIRMASS SO KCMH AND
KLCK MAY REMAIN ON THE EDGE OF THE CLEARING THROUGH MUCH OF THE
MORNING. 00Z NAM AND GFS HAVE TRENDED A LITTLE SLOWER WITH ONSET
OF PCPN FOR TONIGHT. HOWEVER...WHILE BETTER FORCING REMAINS OFF
TO OUR WEST THROUGH 06Z...SOME WEAKER ISENTROPIC LIFT WILL DEVELOP
ACROSS OUR AREA LATER THIS AFTERNOON INTO THIS EVENING. THIS COULD
SUPPORT A FEW SHOWERS BUT CHANCE APPEARS LOW ENOUGH TO LEAVE TAFS
DRY THROUGH THIS AFTERNOON. WILL THEN ALLOW FOR A VCSH TO WORK
ITS WAY IN FROM THE WEST THROUGH THE EVENING HOURS WITH STEADY
PCPN AND LOWERING CIGS/VSBYS MOVING INTO THE WEST TOWARD 06Z.
OUTLOOK...MVFR/IFR CIGS WILL LINGER THROUGH FRIDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HAWBLITZEL
NEAR TERM...HAWBLITZEL
SHORT TERM...HAWBLITZEL
LONG TERM...CONIGLIO
AVIATION...JGL
