FXUS61 KILN 101143
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
643 AM EST THU DEC 10 2009
.SYNOPSIS...
LOW PRESSURE OVER SOUTHERN QUEBEC WILL LIFT NORTHEAST TO THE
CANADIAN MARITIMES BY FRIDAY MORNING. MEANWHILE...HIGH PRESSURE
OVER THE CENTRAL AND SOUTHERN PLAINS WILL GRADUALLY BUILD EAST INTO
THE OHIO VALLEY THROUGH FRIDAY NIGHT. AN UPPER LEVEL WEATHER
DISTURBANCE WILL BRING THE NEXT THREAT FOR PRECIPITATION SATURDAY
NIGHT INTO SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
HAVE USED A BLEND OF THE NAM-WRF AND RUC MODEL FOR THE NEAR TERM
FORECAST.
THE SRN FRINGE OF THE POLAR VORTEX WILL REMAIN ACROSS THE GREAT
LAKES AND THE OHIO VALLEY TODAY. THIS WILL RESULT IN COLD
TEMPERATURES. THE COMBINATION OF SHALLOW MOISTURE...SHALLOW
INSTABILITY AND AN AXIS OF SHEAR VORTICITY ALOFT WAS PRODUCING
MAINLY SCATTERED FLURRIES ACROSS THE REGION THIS MORNING. AM
EXPECTING MOST OF THE FLURRY ACTIVITY TO WANE FROM SW TO NE THIS
MORNING AS AFOREMENTIONED SHEAR AXIS LIFTS OFF TO THE NORTHEAST.
OTHERWISE CLOUDY TO MOSTLY CLOUDY SKIES WILL BEGIN TO SCATTERED
FROM SW TO NE TODAY AS A SFC RIDGE AXIS BUILDS INTO THE OHIO
VALLEY. IT WILL CONTINUE TO BE BRISK AS THE SFC PRESSURE GRADIENT
BETWEEN BUILDING HIGH PRESSURE AND DEPARTING LOW PRESSURE OVER SE
CANADA REMAINS SOMEWHAT TIGHT. WITH DAY TIME MIXING...WINDS COULD
GUST BETWEEN 30 AND 40 MPH WITH THE STRONGEST GUSTS EXPECTED ACRS
THE NORTH. HIGH TEMPERATURES WILL BE A LITTLE TRICKY TODAY.
MESOSCALE MODELS SUGGEST LOCATIONS ALONG AND SE OF I-71 WILL SEE A
SMALL REBOUND IN TEMPERATURES FROM THIS MORNINGS LOWS.
HOWEVER...THEY ALSO INDICATE THAT THE WHITEWATER/MIAMI VALLEY AND
WEST CENTRAL OHIO MAY STRUGGLE TO WARM IF AT ALL. IN FACT...THE
RUC MODEL SUGGESTS TEMPERATURES MAY SLIGHTLY FALL IN THIS REGION
AS ARCTIC AIR CONTINUES TO ADVECT EASTWARD. HAVE ALLOWED FOR A
SLIGHT DIURNAL RISE IN THE NW...BUT DAY SHIFT WILL HAVE TO WATCH
IF THE RUC MODEL ENDS UP BEING RIGHT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
THE SRN FRINGE OF THE POLAR VORTEX WILL BEGIN TO LIFT NE ON
FRIDAY. MEANWHILE...HIGH PRESSURE OVER THE CENTRAL AND SOUTHERN
PLAINS WILL GRADUALLY BUILD INTO THE OHIO VALLEY THROUGH FRIDAY
NIGHT. SKIES WILL BECOME CLEAR/MOSTLY CLEAR TONIGHT WITH MOSTLY
SUNNY CONDITIONS EXPECTED ON FRIDAY. LOWS TONIGHT WILL NOT BOTTOM
OUT AS MUCH AS IT COULD UNDER CLEAR SKIES GIVEN LINGERING PRESSURE
GRADIENT. MOST LOCATIONS WILL DROP INTO THE 10 TO 15 DEGREE RANGE.
A MODIFYING AIRMASS WILL ALLOW TEMPERATURES TO WARM INTO THE UPPER
20S NORTH TO THE MID 30S FAR SOUTH ON FRIDAY...WHICH IS STILL COLD
FOR EARLY DECEMBER. LOWS FRIDAY NIGHT WILL RANGE FROM THE MID
TEENS TO THE LOWER 20S.
AFOREMENTIONED POLAR VORTEX IS EXPECTED TO LIFT BACK NORTH INTO
CANADA THIS WEEKEND. THIS WILL ALLOW THE UPR LVL PATTERN ACRS THE
SRN AND ERN UNITED STATES TO BECOME WEST/SOUTHWEST. HIGH PRESSURE
OVER THE OHIO VALLEY SATURDAY MORNING WILL MOVE OFF THE MID
ATLANTIC SEABOARD BY SUNDAY. UPR LVL FLOW PATTERN WILL BE
PROGRESSIVE...ALLOWING AN EMBEDDED UPR LVL DISTURBANCE TO QUICKLY
CROSS THE FORECAST AREA ON SUNDAY. ISENTROPIC LIFT AND SOME
DYNAMIC LIFT WITH THE DISTURBANCE WILL BRING THE NEXT CHANCE OF
PCPN LATE SATURDAY NIGHT INTO SUNDAY. AT THIS TIME...TEMPERATURES
SHOULD MODERATE ENOUGH FOR THE PCPN TO FALL IN LIQUID FORM ALONG
AND SOUTH OF THE OHIO RIVER. POINTS TO THE NORTH MAY END UP SEEING
A WINTRY MIX OF SNOW...SLEET AND FREEZING RAIN LATE SATURDAY NIGHT
INTO SUNDAY MORNING AS TEMPERATURES NEAR THE SFC HOVER AT OR
SLIGHTLY BELOW FREEZING. ALL LOCATIONS SHOULD TRANSITION OVER TO
RAIN DURING THE DAY SUNDAY BEFORE PCPN EXITS OFF TO THE EAST.
GIVEN THE UNCERTAINTY OF PCPN TYPE AT THIS JUNCTURE...HAVE KEPT A
MENTION OF A RAIN/SNOW MIX NORTH OF THE OHIO RIVER. LATER FORECASTS
WILL HAVE TO HONE IN ON PCPN TYPE.
HAVE RAISED TEMPERATURES FOR THIS WEEKEND DUE TO INCREASING WARM
AIR ADVECTION ON SOUTHERLY WINDS.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
UPR LVL PATTERN IS FORECAST TO TRANSITION BACK TO A NORTHWESTERLY
FLOW EARLY NEXT WEEK. THIS CHANGE WILL SEND A COLD FRONT ACROSS
OUR REGION LATE MONDAY OR TUESDAY. HAVE MAINTAINED CHANCE POPS
DURING THIS PERIOD. LONG RANGE MODELS BEGIN TO DIVERGE FROM MID TO
LATE NEXT WEEK IN TERMS OF HOW MUCH COLD AIR FILTERS BACK INTO THE
LOWER GREAT LAKES AND OHIO VALLEY. GIVEN HIGH VARIABILITY AT THIS
TIME FRAME...HAVE OPTED TO KEEP PREVIOUS FORECAST IN TACT.
&&
.AVIATION /12Z THURSDAY THROUGH MONDAY/...
BACK EDGE OF MVFR CIGS NOW INTO INDIANA...WITH SHSN LINGERING
THROUGH AT LEAST 15-16Z MOST LOCATIONS. WHILE VSBYS NOT AN ISSUE
FOR THE MOST PART...HAVE INCLUDED EARLY TEMPO GROUP TO ACCOUNT FOR
OCCASIONAL MVFR VSBYS WHICH STILL CAN OCCUR. LL DRYING WILL OCCUR
IN THE SW...KCVG/KLUK AFTER 16-17Z...WITH CIGS LIFTING AND
SCATTERING BEFORE SKC BY 21Z IN THE WEST. SKC IN THE EAST NOT TO
HAPPEN TIL ABOUT OR AFTER 04Z. WIND GUSTS TO 25-30KTS IN THE
AFTERNOON.
OUTLOOK...MVFR CEILINGS POSSIBLE ON SUNDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...HICKMAN
NEAR TERM...HICKMAN
SHORT TERM...HICKMAN
LONG TERM...HICKMAN
AVIATION...JDR
