-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KILN 110127
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
927 PM EDT THU APR 10 2014

.SYNOPSIS...
A COLD FRONT WILL SAG SOUTHEAST INTO THE REGION TONIGHT. THIS
FRONT WILL EVENTUALLY SETTLE ALONG AND SOUTH OF THE OHIO RIVER AS
A STATIONARY FRONT BY FRIDAY NIGHT. SOUTHERLY FLOW WILL RETURN ON
SATURDAY AS THE FRONT MOVES BACK NORTH AS A WARM FRONT.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
-- Changed Discussion --
ADJUSTED TEMPERATURES AND DEWPOINTS ALONG WITH THE DECREASING
WINDS TO HAVE OBSERVED VALUES A LITTLE MORE WEIGHTED IN THE NEXT
FEW HOURS. LOWERED THE CHANCE FOR SHOWERS SLIGHTLY IN THE HERE AND
NOW GIVEN NW CWA WAS IN THE LIKELY CATEGORY WITHOUT PRECIP
YET...THOUGH CLOSE BY. WHILE THE THREAT FOR THUNDERSTORMS IS
DECREASING...THE ACTIVITY IS JUST GETTING GOING NOW AND I DID NOT
FEEL THAT REMOVING THUNDER FROM A DEVELOPING SYSTEM WAS THE WAY TO
HANDLE THE EVENING UPDATE. SCALED BACK THE QPF FROM THE SYSTEM AS
THIS APPEARED A BIT OVERDONE.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
UPR LVL S/WV WILL EXIT TO THE EAST ON FRIDAY ALONG WITH A
WEAKENING/SHIFTING LOW LEVEL JET TO THE EAST. POPS WILL REMAIN
HIGH ACRS THE SOUTHEAST CWFA EARLY ON...THEN THEY WILL DIMINISH
INTO THE AFTERNOON HOURS AS THE FORCING DECREASES AND MOVES AWAY
FROM A SLOW-MOVING FRONTAL BOUNDARY. WE SHOULD SEE SOME SUNSHINE
ACRS THE NRN ZONES WITH CLOUDS HANGING TOUGH ALONG AND SOUTH OF
THE OHIO RIVER. HIGHS WILL RANGE FROM THE LOWER TO MID 60S.

FOR FRIDAY NIGHT...FRONTAL BOUNDARY WILL BECOME STATIONARY ALONG
AND SOUTH OF THE OHIO RIVER. PRECIPITATION SHOULD COME TO END BY
THEN. WITH RECENT RAINFALL...LIGHT WINDS...AND WITH PARTIAL
CLEARING...SREF ENSEMBLES INDICATE THE POSSIBILITY OF LOW CLOUDS
AND/OR FOG FORMING...ESPECIALLY ACRS THE SRN TWO THIRDS OF THE CWFA.
GIVEN THAT FOG IS OFTEN HARD TO PREDICT...ESPECIALLY THIS FAR
OUT...HAVE NOT MENTIONED IT YET IN THE FORECAST...BUT WE WILL
HAVE TO MONITOR TRENDS TO SEE IF A STRONG SIGNAL EXISTS TOMORROW
AT THIS TIME.

FOR SATURDAY INTO SATURDAY NIGHT...STALLED OUT FRONTAL BOUNDARY
WILL MOVE NORTH AS A WARM FRONT AS UPR LVL FLOW BEGINS TO BUCKLE
AND LOW PRESSURE DEVELOPS ACROSS THE WESTERN GREAT LAKES. LOW
LEVEL MOISTURE AND INSTABILITY WILL INCREASE ALONG AND BEHIND THE
WARM FRONT ON SATURDAY. OTHER THAN THE BOUNDARY ITSELF...THERE
SEEMS TO BE A LACK OF GOOD FORCING. THUS...HAVE CONTINUED TO LIMIT
POPS TO SLIGHT CHANCE FROM LATE SATURDAY MORNING INTO SATURDAY
EVENING AS THE WARM FRONT LIFTS NORTH. INCREASING SOUTHERLY FLOW
WILL ALLOW TEMPERATURES TO WARM INTO THE LOWER AND MID 70S ON
SATURDAY FOLLOWED BY WARM NIGHTTIME READINGS IN THE 50S SATURDAY
NIGHT.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
THE FIRST HALF OF THE EXTENDED FORECAST PERIOD WILL BE
ACTIVE...GENERALLY FROM THE MIDDLE OF THE COUNTRY TO THE EAST COAST.
THE ILN CWA WILL BE IN A WARM ADVECTION PATTERN TO START THINGS OFF
ON SUNDAY...WITH ANY CHANCES OF PRECIPITATION ASSOCIATED WITH THE
LEADING EDGE OF THE WARM AIR ALOFT MOVING JUST NORTH OF THE AREA.
THE MAIN AREA OF PRECIPITATION...ASSOCIATED WITH A SURFACE FRONTAL
BOUNDARY THROUGH THE GREAT LAKES...WILL PIVOT AND ACQUIRE MORE OF A
NORTH-TO-SOUTH ORIENTATION BY MONDAY MORNING.

DISTINCT SHORTWAVES IN THE NORTHERN AND SOUTHERN STREAMS (SLIGHTLY
MORE OBVIOUS ON THE 12Z ECMWF COMPARED TO OTHER MODELS) WILL DRIVE
TWO MAIN WAVES OF PRECIPITATION OVER THE EASTERN HALF OF THE
COUNTRY. THE FIRST WAVE...ALONG AND BEHIND THE COLD FRONT...IS THE
ONE THAT IS CERTAIN TO AFFECT THE ILN CWA. LIKELY POPS HAVE BEEN
USED FROM 15Z MONDAY MORNING THROUGH 00Z THAT EVENING. AN OPEN
SOUTHERLY FEED OF MOISTURE WILL ALLOW FOR A LOW-END THREAT FOR SOME
HEAVY RAIN...BUT WITH MODEL INDICATIONS OF THE SURFACE WAVE TIMING
ON THE FRONT FAVORING THE ILN AREA TO BE IN A RELATIVE MIN OF QPF
AMOUNTS...IT DOES NOT APPEAR TO BE VERY SIGNIFICANT.
FURTHERMORE...WHILE WINDS ARE RATHER STRONG THROUGH THE COLUMN JUST
AHEAD OF THE FRONT...THEIR UNFAVORABLE ORIENTATION (PARALLEL TO THE
FRONT) AND A LACK OF INSTABILITY WILL PRECLUDE A THREAT FOR STRONG
STORMS. THUNDER WILL CERTAINLY BE POSSIBLE...THOUGH THE WELL-DEFINED
THETA-E BOUNDARY WILL PUT AN END TO THAT THREAT BY AFTERNOON FOR
MOST OF THE CWA.

A SECOND WAVE OF PRECIPITATION (ASSOCIATED WITH THE SOUTHERN STREAM
SHORTWAVE) WILL PRIMARILY AFFECT AREAS SOUTH AND EAST OF THE ILN
CWA...BUT THE TREND WITH THE 12Z MODELS HAS BEEN TO HANG THIS OVER
THE AREA A LITTLE LONGER INTO TUESDAY. POPS HAVE BEEN ADJUSTED FOR
THIS. WITH TEMPERATURES COOLING INTO THE LOWER 30S (AT LEAST FOR THE
NORTHERN CWA) ON TUESDAY MORNING...A BRIEF MIXING OF LIGHT RAIN AND
SNOW WILL BE POSSIBLE.

FOR ABOUT 12 HOURS ON EITHER SIDE OF THE FRONTAL
PASSAGE...NON-DIURNAL TEMPERATURES WERE REQUIRED. BASED ON FRONTAL
TIMING (NOT UNTIL MONDAY AFTERNOON)...THE EASTERN HALF OF THE CWA
WILL BE PSEUDO-DIURNAL. HOWEVER...THE WESTERN HALF WILL BEGIN
COOLING OFF (AND FAIRLY QUICKLY) AFTER NOON.

COOL AND DRY SURFACE HIGH PRESSURE WILL MOVE INTO THE GREAT LAKES
AND NORTHERN OHIO VALLEY ON WEDNESDAY...SHIFTING EAST ON THURSDAY.
AT THE SAME TIME...WEAK RIDGING WILL BE MOVING INTO THE EASTERN HALF
OF THE COUNTRY. THIS POINTS THE WAY TOWARD A GRADUAL WARMING AND
MOISTENING TREND THROUGH THE END OF THE WEEK...BUT DRY CONDITIONS
ARE EXPECTED THROUGH FRIDAY. WIND DIRECTIONS AT THE SURFACE WILL NOT
REALLY BE FAVORABLE FOR MUCH WARM ADVECTION ON THURSDAY (WITH A
SIGNIFICANT EASTERLY COMPONENT)...THOUGH ALOFT...TEMPERATURES AND
HIGH CLOUDS WILL BEGIN TO INCREASE.

&&

.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
BIGGEST CHANGE TO THE FORECAST WAS THE REMOVAL OF THUNDER WITH
FROPA OVERNIGHT TONIGHT. UPSTREAM OBSERVATIONS ARE SHOWING A
DEARTH OF RETURNS ON THE RADAR BUT THAT WAS NOT NECESSARILY
UNEXPECTED THROUGH THIS TIME. EXPECT THE FRONT TO BECOME MORE
ACTIVE WITH SHOWERS AS THE EVENING PROGRESSES TO THE OVERNIGHT
HOURS.

DID NOT SEE THE FEATURES EXPECTED HIGHER UP WITH A H5 S/W OR
STRONG VORT MAX MOVING THROUGH...AT LEAST ENOUGH TO SUPPORT
THUNDER. WITH THE STRONG SW WINDS TODAY THERE WILL BE ENOUGH
MOISTURE TO PRIME SHOWERS MOVING SE WITH THE FROPA TONIGHT...BUT
NOT NEARLY ENOUGH AS THE GFS IS SHOWING.

ANY LOWER CIGS IN THE MVFR RANGE WILL OCCUR IN THE 8-12Z TIME
FRAME WITH THE HIGHEST POTENTIAL FOR SHOWERY ACTIVITY. SKIES WILL
CLEAR OUT TOMORROW AFTERNOON AND WINDS WILL GO VARIABLE AS A POST-
FRONTAL HIGH SETTLES OVER THE REGION.

OUTLOOK...MVFR CIGS AND VSBYS ALONG WITH A THUNDERSTORM ARE
POSSIBLE MONDAY.

&&

.FIRE WEATHER...
A RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM FOR THE SOUTHEAST
PORTION OF THE CWFA DUE TO GUSTY SOUTHERLY WINDS AND LOW RELATIVE
HUMIDITIES. WINDS WILL DIMINISH AFTER SUNSET AS DIURNAL MIXING
WANES AS THE SURFACE DECOUPLES FROM THE LOWER ATMOSPHERE. THE
SURFACED PRESSURE GRADIENT WILL BEGIN TO RELAX AS WELL. RELATIVE
HUMIDITIES WILL RECOVER AS TEMPERATURES COOL AND LOW LEVEL
MOISTURE ADVECTS IN FROM THE SOUTHWEST.

&&

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

&&

$$
SYNOPSIS...HICKMAN
NEAR TERM...FRANKS
SHORT TERM...HICKMAN
LONG TERM...HATZOS
AVIATION...FRANKS
FIRE WEATHER...