828
FXUS61 KILN 220016
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
816 PM EDT SUN MAR 21 2010
SYNOPSIS
LOW PRESSURE OVER THE LOWER OHIO VALLEY WILL CONTINUE TO OCCLUDE
AS IT MOVES INTO THE UPPER OHIO VALLEY THROUGH MONDAY NIGHT.
NORTHWESTERLY UPPER FLOW WILL ALLOW HIGH PRESSURE TO BRIEFLY BUILD
INTO THE REGION WEDNESDAY AND WEDNESDAY NIGHT.
NEAR TERM /UNTIL 6 AM MONDAY MORNING/
LARGE AREA OF RAIN OVER MUCH OF THE LOWER OHIO VALLEY WILL
CONTINUE TO LIFT NORTH AND EAST TONIGHT AS HIGH-THETA-E AIR OVER
THE TN VALLEY IS ADVECTED ALONG AND NORTH OF AN ELEVATED BOUNDARY
OVER KY/TN. EXPECT PRECIP TO INCREASE IN COVERAGE ACROSS ERN TN
AND SOUTHERN OHIO TONIGHT AS STRENGTHENING 850 HPA JET INCREASES
THE ADVECTION OF THETA-E AND RESULTS IN INCREASING LOW LEVEL
CONVERGENCE. THIS ENHANCEMENT OF PRECIP RATES WILL REACH NEAR THE
OHIO RIVER BY 06Z...AND INTO THE CENTRAL CWA BY 12Z. CONTINUED 100
POPS ACROSS THE SOUTHERN HALF OF THE CWA...WHERE RAINFALL AMOUNTS
BETWEEN .5 AND 1-INCH APPEAR POSSIBLE BY EARLY MON MORNING.
SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/
ELEVATED FRONTAL BOUNDARY WILL BE JUST NORTH OF THE OHIO
RIVER EARLY MONDAY MORNING...WITH VERTICALLY-SLOPING LOW-LEVEL
CONVERGENCE AXIS EXTENDING ACROSS MUCH OF THE NORTHERN 2/3 OF THE
CWA. THIS WILL LIKELY FAVOR AN ONGOING WIDESPREAD BAND OF RAIN
ENCOMPASSING THIS AREA EARLY MONDAY MORNING. EXPECT THAT WEAK LOW-
LEVEL FRONTOLYSIS WILL ACT TO DECREASE THE INTENSITY AND COVERAGE
OF PRECIP MONDAY MORNING. HOWEVER...MODELS CONTINUE TO INDICATE
PRECIP REDEVELOPING ACROSS THE EASTERN CWA LATER MONDAY AFTERNOON
AS SFC LOW TRACKS JUST EAST OF THE CWA BORDER. THIS LOW TRACK WILL
KEEP BULK OF ELEVATED INSTBY FOCUSED TO THE EAST...SO DID NOT
INCLUDE MENTION OF THUNDER AT THIS TIME. PRECIP WILL LIKELY LINGER
INTO MONDAY NIGHT...ESPECIALLY ACROSS THE EASTERN CWA...IN
VICINITY OF INVERTED SFC TROUGH EXTENDING SOUTHWESTWARD FROM SFC
LOW.
AS SFC LOW TRACKS EAST ON TUES...WEAK SFC RIDGING WILL BUILD IN
FROM THE SOUTH...AND SHOULD ALLOW SKIES TO CLEAR FROM WEST TO EAST
BY TUESDAY EVENING. WITH MOSTLY CLEAR SKIES EXPECTED TUESDAY
NIGHT...TRENDED TOWARD COOLER END OF GUIDANCE FOR TEMPS...IF NOT A
DEGREE OR TWO LOWER.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
REGION WILL BE UNDER SOME SHORT WAVE RIDGING ON WEDNESDAY WITH AN
ASSOCIATED SURFACE RIDGE OF HIGH PRESSURE SLIDING EAST ACROSS THE
AREA THROUGH THURSDAY. 12Z MODELS HAVE TRENDED WEAKER AND A LITTLE
FARTHER SOUTH WITH APPROACHING SHORT WAVE/LOW LATER IN THE WEEK.
EXPECT TO SEE A GRADUAL INCREASE IN CLOUDS AHEAD OF THIS SYSTEM ON
THURSDAY BUT INCREASING SOUTHERLY FLOW SHOULD ALLOW FOR A BIT OF A
WARM UP IN TEMPERATURES.
THE 00Z ECMWF IS STILL TRYING TO HANG ON TO A WEAK CLOSED LOW AT 500
MB TO OUR WEST THURSDAY NIGHT BUT THE 12Z GEM AND GFS JUST HAVE AN
OPEN WAVE AND IT SEEMS THE ECMWF MAY BE TRENDING THIS WAY. THE GEM
IS ALSO CONSIDERABLY FARTHER TO THE SOUTH THAN THE ECMWF AND
GFS...ALTHOUGH THEY BOTH HAVE TRENDED A BIT FARTHER SOUTH TOO. WILL
THEREFORE BACK OFF SOME ON POPS ACROSS OUR NORTH AND WITH THIS
WEAKER/MORE SOUTHERN TREND...WILL NOT GO ANY HIGHER THAN A 30 POP
ACROSS THE SOUTH THROUGH FRIDAY. IN A FAIRLY PROGRESSIVE FLOW
PATTERN...MID LEVEL RIDGING WILL BUILD BACK IN ON SATURDAY AHEAD OF
ANOTHER SHORT WAVE THAT WILL MOVE INTO THE AREA LATE ON SUNDAY. WE
MAY EVENTUALLY NEED SOME POPS ACROSS THE WEST SUNDAY AFTERNOON BUT
FOR NOW WILL KEEP AT DRY AS BEST CHANCE LOOKS TO BE SUNDAY NIGHT
INTO MONDAY.
PREVIOUS DISCUSSION FOLLOWS...
SURFACE HIGH PRESSURE WILL THEN BEGIN TO BUILD IN FROM THE
NORTHWEST TUESDAY NIGHT INTO WEDNESDAY. THERE ARE SOME DIFFERENCES
BETWEEN THE MODELS WITH THE 12Z GFS THE STRONGEST WITH THE HIGH
AND THE 12Z GEM THE WEAKEST. THE 00Z ECMWF APPEARS TO BE IN
BETWEEN AND WILL TREND THE FORECAST THAT WAY. WITH THAT IN
MIND...WILL KEEP THE FORECAST DRY THROUGH WEDNESDAY NIGHT. THE
STRENGTH OF THE HIGH WILL PLAY A ROLE IN HOW FAST THE NEXT SHORT
WAVE APPROACHES FROM THE WEST LATER IN THE WEEK. AGAIN...THE 12Z
GEM IS THE MOST PROGRESSIVE WITH THIS NEXT SYSTEM WITH THE 12Z GFS
THE SLOWEST. WILL ONCE AGAIN LEAN TOWARD THE MIDDLE OF THE ROAD
ECMWF AND BRING IN SOME LOW CHANCE POPS THURSDAY INTO FRIDAY.
TEMPERATURES THROUGH MID WEEK WILL BE DEPENDENT ON THE STRENGTH OF
THE HIGH AND HOW FAST THE CLOUDS MOVE IN AHEAD OF THE NEXT SYSTEM.
WITH SOME UNCERTAINTY...WILL NOT STRAY TOO FAR FROM HPC GUIDANCE
FOR TEMPERATURES.
AVIATION /00Z MONDAY THROUGH FRIDAY/
UPPER LEVEL LOW OVER THE LOWER MS VLY TO TRACK SLOWLY ENE INTO THE
SRN TN VLY BY MONDAY MORNING AND THEN OFF DELMARVA ON TUE. AXIS OF
STRONG LOW LEVEL CONVERGENCE ASSOCIATED WITH 45-50KT LOW LEVEL
JET TO PIVOT INTO SRN OHIO TNGT AND INTO NRN OHIO BY MONDAY MORNING.
EXPECT RAIN SHOWERS TO OVERSPREAD ALL TAF SITES WITH MVFR CONDITIONS
DEVELOPING. AS THE SFC WAVE ASSOCIATED WITH THE TROF MOVES INTO SRN
OHIO A SECOND AXIS OF FAVORABLE FORCING DEVELOPS EARLY MONDAY AND
PIVOT NORTH. HAVE MVFR CONDITIONS CONTINUING BUT A PERIOD OF IFR
CONDITIONS WL LKLY OCCUR ESPECIALLY ALONG AND JUST NORTH OF THE
TROF AXIS.
WINDS WILL BE OUT OF THE NORTHEAST TONIGHT AND BECOME GUSTY
AND THEN SHIFT TO THE SOUTHWEST ON MONDAY MORNING ACRS THE SRN
TAF SITES AND THEN EVENTUALLY SHIRTING NW BY MONDAY EVENING.
OUTLOOK...MVFR CIGS EXPECTED ON TUESDAY.
ILN WATCHES/WARNINGS/ADVISORIES
OH...NONE.
KY...NONE.
IN...NONE.
SYNOPSIS...HAWBLITZEL
NEAR TERM...HAWBLITZEL
SHORT TERM...HAWBLITZEL
LONG TERM...JGL
AVIATION...AR
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