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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 210017
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
817 PM EDT SUN APR 20 2014

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO EXTEND ACROSS THE REGION
TODAY...BEFORE MOVING OFF TO THE EAST TONIGHT. A COLD FRONT WILL
MOVE THROUGH THE AREA LATE MONDAY NIGHT INTO TUESDAY
MORNING...BRINGING RAIN TO THE AREA. ANOTHER AREA OF HIGH PRESSURE
WILL BUILD IN FOR THE MIDDLE OF THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
SURFACE HIGH PRESSURE IS CENTERED OVER NEW ENGLAND...AND WILL MOVE
OFF THE EAST COAST TONIGHT. THIS HIGH EXTENDS INTO THE OHIO VALLEY
AND EVEN AS FAR SOUTH AS THE NORTH-CENTRAL GULF COAST...WITH VERY
DRY CONDITIONS IN PLACE. THIS IS ALLOWING FOR LARGE DIURNAL
SWINGS...AS TEMPERATURES HAVE REACHED THE MID 70S ACROSS THE ILN
CWA (WITH SOME AREAS EVEN GETTING INTO THE UPPER 70S). THE MIXED
BOUNDARY LAYER HAS ALLOWED FOR SOME SWINGS IN THE WINDS...WITH
LIGHT AND VARIABLE CONDITIONS INTERSPERSED WITH BRIEF GUSTY
PERIODS OUT OF THE SOUTHEAST.

THOUGH A FEW PATCHES OF CIRRUS MAY CONTINUE TO MOVE THROUGH THE
AREA TONIGHT...RADIATIONAL COOLING WILL BE FAIRLY EFFECTIVE. WITH
A WARMER STARTING POINT AND LIGHT SOUTHERLY FLOW...TEMPERATURES
WILL CERTAINLY BE WARMER THAN THIS MORNING...THOUGH THE FAR
EASTERN CWA AND OTHER OUTLYING LOCATIONS WILL STILL BE CAPABLE OF
DROPPING INTO THE MID TO UPPER 40S.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
ON MONDAY...THE ILN CWA WILL REMAIN OUT AHEAD OF A DEVELOPING COLD
FRONT...IN A REGIME OF SOUTHWEST WIND FLOW. CLOUDS WILL GRADUALLY
BEGIN INCREASING DURING THE DAY...WITH ENOUGH MOISTURE BUILDING IN
TO SUPPORT CUMULUS AS WELL AS HIGHER CLOUDS. HOWEVER...IT DOES NOT
APPEAR THAT THESE CLOUDS WILL HAVE A SUBSTANTIAL IMPACT ON
TEMPERATURES...WITH THE CHANGE IN FLOW SUPPORTING VALUES A FEW
DEGREES HIGHER THAN SUNDAY. THE BOUNDARY LAYER WILL BE WELL-MIXED
AGAIN...SO A FEW GUSTS TO AROUND 15-20 KNOTS WILL BE POSSIBLE.

WEAK INSTABILITY WILL BEGIN TO DEVELOP NEAR THE PEAK HEATING OF
THE DAY...AND THE SPC WRF-NMM IS NOW CLOSE ENOUGH IN RANGE TO
DEPICT SOME WIDELY SCATTERED CONVECTION OVER THE WESTERN HALF OF
THE ILN FORECAST AREA BY LATE AFTERNOON (EVEN THOUGH THE MAIN FRONTAL
FORCING WILL NOT YET HAVE ARRIVED). SLIGHT CHANCE POPS WERE
EXTENDED INTO THE AREA A LITTLE EARLIER THAN WITH THE PREVIOUS
FORECAST...THOUGH MOST LOCATIONS WILL REMAIN DRY.

BY MONDAY EVENING...THE FRONT WILL BEGIN ITS APPROACH...BUT MOST
OF THE FORECAST PRECIPITATION EXISTS WELL AHEAD OF IT (MORE
CLOSELY ALIGNED WITH FORCING SLIGHTLY ALOFT). PERHAPS BECAUSE OF
THE LACK OF FORCING DEFINITION IN THE LOW-LEVELS...AND A MOISTURE
FEED OF QUESTIONABLE QUALITY...IT IS NOT SURPRISING THAT QPF
DEPICTIONS FOR THIS MINOR EVENT ARE SPOTTY AND PATCHY (AND NOT AT
ALL CONSISTENT FROM MODEL TO MODEL). THOUGH RAIN IS LIKELY TO
AFFECT THE ENTIRE CWA AT SOME POINT IN A 12-TO-18 HOUR
PERIOD...THESE TIMING AND PLACEMENT CONCERNS PRECLUDE THE
INCLUSION OF CATEGORICAL POPS FOR THIS FORECAST CYCLE.
PRECIPITATION FORECASTS ARE GENERALLY AROUND A QUARTER INCH OR
LESS...AND WITH ONLY WEAK INSTABILITY...NO HWO-WORTHY HAZARDS ARE
EXPECTED EARLY THIS WEEK (THOUGH SOME THUNDER IS POSSIBLE IN THE
WEAK INSTABILITY). MODELS DO GENERALLY HAVE A GOOD TIMING
AGREEMENT ON THE DEPARTURE OF THE MOISTURE AS THE FRONT
PASSES...WITH THE CWA APPEARING TO BE COMPLETELY DRY BY 18Z.

THE CHANGING AIR MASS WILL LEAD TO COOLER CONDITIONS ON
TUESDAY...THOUGH SOME RECOVERY IN THE SUN WILL BE POSSIBLE AS
SKIES CLEAR BEHIND THE FRONT. HOWEVER...PERSISTENT COLD ADVECTION
ON NNW FLOW WILL ALLOW FOR TEMPERATURES TO DROP INTO THE 30S ON
TUESDAY NIGHT...WITH MID 30S POSSIBLE IN THE NORTHERN AND
NORTHWESTERN CWA.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
-- Changed Discussion --
HAVE LEANED MORE WITH WPC/S ADVICE WHICH IS TO USE A BLEND OF THEIR
GUIDANCE...THE LATEST GFS AND DISCOUNT THE 00Z ECMWF AND THE 12Z
ECMWF FOR THE FORECAST INTO THE WEEKEND/EARLY NEXT WEEK WHICH PUSHES
A MORE ENERGETIC SFC CYCLONE THROUGH THE CNTRL PLAINS AND INTO THE
OHIO VALLEY.

ON WEDNESDAY...SURFACE HIGH PRESSURE WILL BE PUSHING EAST ACROSS THE
GREAT LAKES AND OHIO VALLEY. IT WILL BE COOLER WITH HIGHS RANGING
FROM THE UPPER 50S NORTH TO THE LOWER 60S ALONG AND SOUTH OF THE
OHIO RIVER.

FOR WEDNESDAY NIGHT INTO THURSDAY NIGHT...NEXT COLD FRONT TO AFFECT
OUR REGION IS STILL POISED TO ARRIVE THURSDAY NIGHT. TIMING KEEPS
CHANGING SOME IN TERMS OF PCPN ARRIVAL FROM RUN TO RUN. THERE LOOKS
LIKE ENOUGH DYNAMICS...MOISTURE AND INSTABILITY TO GO WITH LIKELY
POPS ACRS OUR AREA THURSDAY NIGHT. BEFORE HAND...PCPN WILL ARRIVE IN
THE FAR WRN ZONES LATE IN THE DAY ON THURSDAY. WAA AHEAD OF THE
FRONT WILL PUSH HIGHS INTO THE UPPER 60S AND MID 70S ON THURSDAY.

ON FRIDAY...FRONT WILL MOVE EAST...AND IT LOOKS LIKE WE WILL DRY
OUT. CAA WILL BE BEGINNING ON FRIDAY BUT WILL BE DELAYED SOME.
SO...UNDER PARTLY CLOUDY SKIES...HIGHS WILL RANGE FROM THE UPPER 60S
NW TO THE MID 70S FAR SOUTHEAST.

FOR FRIDAY NIGHT INTO SATURDAY NIGHT...A QUITE LARGE UPR LVL CLOSED
LOW WILL TRAVERSE THE GREAT LAKES REGION. AT THIS TIME...IT LOOKS
LIKE ANY PCPN WILL REMAIN NEAR THE LAKES THEMSELVES. SO...SKIES
SHOULD BE PARTLY CLOUDY WITH A COOLING TREND EXPECTED INTO THE
WEEKEND AS HIGHS DROP TO BELOW NORMAL READINGS FOR LATE APRIL.

ON SUNDAY...SURFACE HIGH PRESSURE IS FORECAST TO PUSH THROUGH THE
REGION BEHIND DEPARTING UPR LVL CLOSED LOW. HIGHS WILL REMAIN COOL
FOR LATE APRIL.
-- End Changed Discussion --

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
-- Changed Discussion --
AREA OF BROKEN CI WILL AFFECT THE TAFS FOR THE FIRST COUPLE OF
HOURS OF THE TAFS...THEN SCT CONDITIONS ARE EXPECTED TO TAKE OVER
UNTIL ABOUT 06Z. ADDITIONAL CI WILL WORK BACK INTO THE TAFS AHEAD
OF AN EJECTING H5 S/W. CIGS WILL LOWER SOME AFT 12Z AS AC DECK
WORKS IN.

LOW LEVEL MOISTURE WILL BE SLOW TO POOL AHEAD OF ADVANCING
CDFNT...SO ANY CU THAT DEVELOPS TOMORROW UNDER THE AC SHOULD BE SCT.

CONSENSUS OF LATEST MODEL RUNS KEEP PCPN W OF THE TAFS THRU 00Z.
AT CVG IN THE 30 HOUR PORTION BROUGHT MVFR PREVAIL SHOWERS IN
AROUND 03Z. MENTIONED A VCTS AS SFC BASED INSTABILITY WILL BE
WAINING BY THAT TIME...BUT MODELS ARE SHOWING A LITTLE ELEVATED INSTABILITY.

OUTLOOK...MVFR CEILINGS AND VISIBILITIES ARE POSSIBLE MONDAY
NIGHT INTO TUESDAY.
-- End Changed Discussion --

&&

.ILN WATCHES/WARNINGS/ADVISORIES...
OH...NONE.
KY...NONE.
IN...NONE.

&&

$$
SYNOPSIS...HATZOS
NEAR TERM...HATZOS
SHORT TERM...HATZOS
LONG TERM...HICKMAN
AVIATION...SITES