000
FXUS61 KILN 060853
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
353 AM EST FRI FEB 6 2009
.SYNOPSIS...
HIGH PRESSURE ACROSS THE UPPER OHIO VALLEY WILL PUSH OFF TO THE
EAST TODAY. AS IT DOES...INCREASING SOUTHERLY FLOW WILL PULL
WARMER AIR UP INTO THE REGION THIS AFTERNOON INTO SATURDAY. A
COLD FRONT WILL THEN PUSH DOWN INTO THE AREA ON SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SURFACE HIGH PRESSURE WILL CONTINUE TO PUSH OFF TO THE EAST TODAY.
ON THE BACK SIDE OF THE HIGH...LOW LEVEL SOUTHWESTERLY FLOW WILL
BEGIN TO INCREASE THROUGH THE AFTERNOON. THIS WILL LEAD TO A DEVELOPING
WAA PATTERN ACROSS THE AREA. THE 00Z GFS AND 00Z NAM STILL HAVE
DISAGREEMENTS ON HOW TO HANDLE LOW LEVEL MOISTURE FIELDS FOR THIS
AFTERNOON. THE GFS CONTINUES TO BE MUCH MORE MOIST BELOW 925 MB
COMPARED TO THE NAM. THIS IS TROUBLING IN THAT THE NAM IS USUALLY THE
MODEL THAT OVERDOES THE LOW LEVEL MOISTURE FIELDS. THE GFS MAY BE RESPONDING
TO SOME MELTING OF THE SNOW PACK. SINCE SURFACE FLOW REMAINS
FAIRLY LIGHT THROUGH THIS AFTERNOON...THINK WAA WILL BE TEMPERED
AT LEAST TO A DEGREE BY THE SNOW ON THE GROUND SO HAVE OPTED TO
STAY NEAR GUIDANCE FOR HIGHS TODAY ACROSS THE NORTH AND EVEN A
LITTLE BELOW IN THE SOUTH. THUS...NOT SURE HOW MUCH OF AN EFFECT
THE MELTING WILL HAVE ON THE LOW LEVEL MOISTURE TODAY. WILL
THEREFORE LEAN TOWARD THE DRIER NAM AND KEEP THINGS MOSTLY SUNNY
TODAY.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
LOW LEVEL MOISTURE DISCREPANCIES CONTINUE INTO THIS EVENING
BETWEEN THE NAM AND GFS...BUT THE NAM BEGINS TO LOOK MORE LIKE THE
MORE MOIST GFS BY 12Z SATURDAY MORNING. AS A RESULT...WILL ALLOW
FOR A GRADUAL INCREASE IN CLOUDS THROUGH THE OVERNIGHT
PERIOD...ESPECIALLY FOR THE NORTHWEST HALF OF THE FA AS A LITTLE
BIT OF DEEPER MOISTURE BEGINS TO WORK ITS WAY IN OVERNIGHT. THIS
SOMEWHAT DEEPER MOISTURE THEN SLOWLY OVERSPREADS THE REST OF THE FA
THROUGH THE DAY ON SATURDAY. WITH SOME CONTINUED WEAK LOW LEVEL
ISENTROPIC LIFT...WILL CONTINUE WITH LOW CHANCE OF SHOWERS
OVERSPREADING THE AREA FROM THE NORTHWEST LATER TONIGHT INTO
SATURDAY.
WITH CONTINUED SOUTHERLY FLOW/WAA AND POSSIBILITY OF SOME
CLOUDS...THINK TEMPS WILL REMAIN FAIRLY STEADY OR DROP OFF JUST A
FEW DEGREES OVERNIGHT. DEPENDING ON HOW MUCH MELTING OCCURS...WITH
WARM/MOIST AIR MOVING OVER SNOW PACK...POSSIBILITY EXISTS FOR SOME
FOG DEVELOPMENT AS WE GO THROUGH THE NIGHT. WILL GO A LITTLE
WARMER THAN GUIDANCE FOR HIGHS ON SATURDAY AS LOW LEVEL SOUTHERLY
FLOW INCREASES AND STRONGER WAA DEVELOPS.
A COLD FRONT WILL DROP DOWN FROM THE NORTH AND PUSH INTO OUR AREA
LATE SATURDAY NIGHT INTO SUNDAY MORNING. FORCING IS FAIRLY WEAK AND
MOISTURE IS STILL SOMEWHAT SHALLOW SO WILL KEEP POPS RELATIVELY
LOW. ANY PCPN SHOULD THEN BEGIN TO TAPER OFF FROM THE NORTH SUNDAY
AFTERNOON AS DRIER AIR WORKS IN BEHIND THE FRONT.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AN ACTIVE...UNSEASONABLY WARM FCST IS IN PLACE THROUGH MUCH OF THE
PERIOD. AFTER THE FRONTAL PASSAGE...A RIDGING PATTERN WILL
TEMPORARILY BUILD IN ACROSS THE CWA BEFORE GIVING WAY LATE ON
MONDAY AS A LOW DEVELOPS ACROSS THE CNTRL PLAINS. AHEAD OF THE
LOW...POPS BEGIN TO INCREASE MON NIGHT INTO TUES WITH ISENTROPIC
LIFT AHEAD OF THE LOW AND WITH A WARM FRONT LIFTING ACROSS THE
AREA ON TUESDAY. WENT WITH A GFS/ECMWF BLEND MONDAY AND
TUESDAY...THEN LEANED MORE TOWARD THE GFS FOR THE REST OF THE FCST
AS THE ECMWF BEGINS TO LAG IN TIMING AND SHIFT THE SFC LOW NWD
INTO ERN CANADA. A CLOSED H5 LOW WILL DEVELOP ACROSS THE PLAINS
AND LIFT NEWD INTO THE GREAT LAKES WEDNESDAY INTO LATE NEXT WEEK.
THIS WILL ALLOW THE CHC FOR ONGOING PRECIP THROUGHOUT THIS PERIOD.
WITH SWRLY FLOW ALOFT LATE MUCH OF NEXT WEEK...HIGHS WILL BE
UNSEASONABLY WARM IN THE 40S/50S WITH LOWS RANGING FROM THE M30S
TO M40S.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
SKC AND LIGHT SOUTHERLY WINDS WILL PREVAIL FOR THE FIRST HALF OF
THE PERIOD. MAIN QUESTION THIS TAF PACKAGE IS HOW MUCH LOW LEVEL
MOISTURE WILL DEVELOP LATER TODAY WITH WARM AIR ADVECTION OVER A
MELTING SNOW PACK...AND WHETHER THIS MOISTURE WILL BE ENOUGH TO
FORM IFR/MVFR LOW CLOUDS THIS AFTERNOON AND EVENING. FOR
NOW...WILL HINT AT THIS POSSIBILITY WITH SCT LOW-END MVFR
CLOUDS...BUT IT WILL LIKELY BE EITHER SKC OR A BKN MVFR/IFR
DECK. THIS MOISTURE MAY ALSO FAVOR SOME SCATTERED FOG/BR...BUT
WITH WINDS PICKING UP TOMORROW NIGHT...KEPT THIS OUT OF ALL TAF
SITES EXCEPT KLUK.
OUTLOOK...MVFR CIGS/VSBYS POSSIBLE SATURDAY INTO SATURDAY
NIGHT...THEN AGAIN TUESDAY.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.
&&
$$
SYNOPSIS...JGL
NEAR TERM...JGL
SHORT TERM...JGL
LONG TERM...RYAN/WOODRUM
AVIATION...HAWBLITZEL