Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 130808
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
408 AM EDT SUN JUL 13 2014

.SYNOPSIS...
A COLD FRONT WILL SLOWLY SAG SOUTHEAST INTO THE REGION THROUGH
TONIGHT. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AHEAD OF THIS
FRONT. ON MONDAY...THIS FRONT WEAKENS AND MOVES SOUTHEAST WHILE
ANOTHER COLD FRONT APPROACHES FROM THE NORTHWEST. THE SECONDARY
COLD FRONT IS EXPECTED TO PASS EAST THROUGH THE AREA MONDAY NIGHT.
AN UNSEASONABLY COOL AIRMASS WILL THEN FOLLOW IN THE WAKE OF THIS
FRONT INTO MID WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
MOSAIC RADAR THIS MORNING DEPICTED A SWATH OF SHOWERS AND EMBEDDED
THUNDERSTORMS EXTENDING FROM SOUTHERN ONTARIO...SOUTHWEST THROUGH
NRN INDIANA...NRN ILLINOIS...THEN INTO THE CENTRAL PLAINS. HIGH
RESOLUTION MODELS INDICATE THAT THE MAIN BULK OF PCPN OVER THE
GREAT LIKES WILL SHIFT EAST/NORTHEAST WITH ITS ASSOCIATED LOW
LEVEL JET AND UPR LVL S/WV THIS MORNING. IN THE MEANTIME...THE
PCPN TO THE WEST WILL TRY TO SAG SOUTHEAST INTO OUR NW/NRN
COUNTIES THROUGH THE MORNING HOURS...LIKELY WEAKENING AS THIS
OCCURS.

THE MAIN FORECAST DILEMMA FOR LATER TODAY INTO TONIGHT WILL BE THE
POTENTIAL FOR ADDITIONAL SHOWER/THUNDERSTORM DEVELOPMENT AND
SUBSEQUENT SEVERE WEATHER/HEAVY RAINFALL. A WEAK COLD FRONT WILL
SLOWLY SAG SOUTHEAST INTO OUR NW CWFA THIS AFTERNOON. VARIOUS HIGH
RESOLUTION MODELS OFFER DIFFER SCENARIOS ON TIMING AND COVERAGE OF
THE SHOWER/THUNDERSTORM DEVELOPMENT IN ASSOCIATION WITH THIS
FRONT. SOME PREVIOUS RUNS INDICATED THAT PERHAPS CONVECTION WOULD
START ALONG THE FRONT AND THEN PROPAGATE SLOWLY SOUTHEAST ACROSS
THE CWFA TOWARD BETTER INSTABILITY. LATER RUNS NOW SUGGEST THAT IF
CURRENT DEBRIS CLOUDS CAN THIN SOME BY THIS AFTERNOON...SHOWERS/STORMS
SHOULD DEVELOP IN PERHAPS A PREFRONTAL CONVERGENT AXIS WHERE
DIFFERENTIAL HEATING MAY ACT AS A PSEUDO FRONT. THIS SEEMS MOST
LIKELY IN THE VICINITY OF THE I-71 CORRIDOR AND POINTS SE. ONCE
THIS OCCURS...THE CONVECTION SHOULD GROW IN COVERAGE AS IT SAGS
SOUTHEAST INTO THE BETTER/HIGHER INSTABILITY. RIGHT NOW...IT LOOKS
LIKE WE SHOULD BE ABLE TO ACHIEVE AT LEAST MODERATE INSTABILITY...
1500 J/KG FOR STORMS TO FEED ON. ALSO...WITH AT LEAST LOW END
MODERATE BULK 0-6KM/0-3KM SHEAR VALUES...THE STORMS SHOULD BE ABLE
TO ORGANIZE IN LINEAR SEGMENTS. AS SUCH...THE MAIN SEVERE WEATHER
THREAT WOULD BE DAMAGING WINDS WITH PERHAPS AN ISOLATED LARGE HAIL
THREAT. THE OTHER POTENTIAL ISSUE WILL BE HEAVY RAIN. PWATS ARE
FORECAST TO CLIMB TO 2.00 TO 2.25 THIS AFTERNOON...WHICH IS 150
PERCENT ABOVE NORMAL FOR MID JULY. THIS VERY MOIST AIRMASS...ALONG
WITH THE EXPECTED SLOW PROGRESSION OF THE CONVECTION TO THE
EAST/SOUTHEAST WILL CERTAINLY POSE A FLOOD THREAT AS THUNDERSTORMS
MAY TRAIN OVER THE SAME AREAS. HOWEVER...GIVEN CURRENT HIGH FFG
VALUES...AND WITH STILL SOME UNCERTAINTY AS TO WHERE THE
CONVECTION WILL START AND THEN PROPAGATE FROM ITS SOURCE
REGION...HAVE DECIDED TO JUST MENTION HEAVY RAIN IN THE ZONES AND
HIGHLIGHT THE THREAT IN THE HWO. THE DAYSHIFT MAY HAVE A BETTER
HANDLE ON THE GREATEST THREAT AREA AND PERHAPS A SHORT TERM FLASH
FLOOD WATCH MAY BE ISSUED. FOR TONIGHT...THE FRONT WILL BECOME
MORE ILL DEFINED AS IT SAGS SOUTHEAST INTO THE HEART OF THE CWFA.
DO NOT LIKE THE NAM/GFS GRID SCALE FEEDBACK WHICH BLOW UP HIGH
QPF VALUES ACRS THE SRN ZONES TOWARD MORNING. AS SUCH...HAVE GONE
WITH THE CONVECTION ALLOWING MODELS WHICH SUGGEST THAT CONVECTION
SHOULD DIMINISH IN COVERAGE TOWARD MONDAY MORNING ACROSS THE
SOUTHERN ZONES. THE NORTHERN ZONES ARE EXPECTED TO REMAIN DRY
OVERNIGHT. HIGHS TODAY WILL BE TRICKY DUE TO CLOUDS/PCPN. THIS
CALLS FOR A BIAS CORRECTED BLEND WHICH YIELDS HIGHS FROM THE LOWER
80S NW TO NEAR 90 SE. OVERNIGHT LOWS WILL RANGE FROM THE MID 60S
NW TO THE LOWER 70S ALONG AND SOUTH OF THE OHIO RIVER.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
A LARGE SCALE ANOMALOUS MID LEVEL CLOSED LOW IS STILL FORECAST TO
DIG SOUTHEAST INTO THE WESTERN GREAT LAKES ON MONDAY. THIS PROCESS
SHOULD SHIFT FIRST AREA OF CONVECTION/CONVERGENT AXIS SOUTHEAST
OF THE REGION WHILE A SECONDARY COLD FRONT APPROACHES THE REGION
FROM THE NW. THERE STILL REMAINS UNCERTAINTY ON THE AMOUNT OF LOW
LEVEL CONVERGENCE THAT IS EXPECTED WITH THE SECONDARY FRONT AS IT
ENTERS OUR WRN CWFA LATE IN THE DAY OR EARLY EVENING. AS SUCH...HAVE
KEPT POPS IN THE CHANCE CATEGORY ON MONDAY WITH 50 PERCENT
EMPLOYED ACRS THE WEST FOR SHOWERS/STORMS. HIGHS ON MONDAY WILL
BE A LITTLE COOLER IN MOST SPOTS...RANGING FROM THE LOWER TO MID
80S.

FOR MONDAY NIGHT INTO TUESDAY...AFOREMENTIONED UPPER LEVEL CLOSED
LOW WILL TRAVERSE SLOWLY ACROSS THE GREAT LAKES. THE COLD FRONT
WILL PUSH EAST THROUGH THE REGION MONDAY NIGHT AND SHOULD BE OUT
OF THE AREA BY TUESDAY MORNING. WILL CONTINUE THE CHANCE FOR
SHOWERS/STORMS UNTIL FRONTAL PASSAGE. AFTER THAT...WE SHOULD BE IN
THE DRY SLOT BEHIND THE FRONT WITH PARTLY CLOUDY SKIES EXPECTED ON
TUESDAY. THE COOL DOWN WILL BEGIN ON TUESDAY WITH HIGHS RANGING
FROM THE LOWER 70S NW TO THE MID 70S SOUTHEAST.

FOR TUESDAY NIGHT...PARTLY CLOUDY SKIES ARE EXPECTED AS WEAK SFC
RIDGING MOVES INTO THE AREA. LOWS WILL BE COOL AND WILL APPROACH
RECORD LOWS FOR JULY 16. LOWS WILL BOTTOM OUT INTO THE LOWER AND
MID 50S.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
HIGH PRESSURE AND AN UNSEASONABLY COOL AIRMASS WILL SETTLE INTO
THE REGION THROUGH MIDWEEK. THE COOL AIRMASS COULD ALLOW FOR A
FEW DIURNAL SHOWERS DURING THE AFTERNOON/EARLY EVENING
WEDNESDAY AND POSSIBLY EVEN THURSDAY. HOWEVER...CHANCE AND
COVERAGE APPEARS LOW ENOUGH AT THIS POINT TO LEAVE OUT OF
FORECAST. THE AIRMASS WILL REMAIN ON THE COOL SIDE WEDNESDAY INTO
THURSDAY AS IT GRADUALLY MODIFIES WITH HIGHS INTO THE MID TO
POSSIBLY UPPER 70S BY THURSDAY. HIGH PRESSURE WILL THEN SLIDE OFF
TO THE EAST THROUGH THE END OF THE WEEK. AS WE TRANSITION INTO
RETURN FLOW...HIGHS BY SATURDAY WILL SLOWLY MODERATE BACK INTO THE
LOWER 80S.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
WHILE GENERALLY TRANQUIL CONDITIONS ARE EXPECTED
OVERNIGHT...SOUTHWESTERLY WINDS WILL BEGIN TO INCREASE IN
INTENSITY BY SUNRISE. SHOWERS AND THUNDERSTORMS CURRENTLY
STRETCHING FROM SOUTHERN MICHIGAN TO NORTHERN ILLINOIS WILL
GRADUALLY WEAKEN AS THEY MOVE INTO THE AREA. HOWEVER...SCATTERED
WEAK SHOWERS WILL CONTINUE TO BE POSSIBLE ALONG A BOUNDARY THAT IS
MOVING SLOWLY TO THE SOUTH. THE FOCUS FOR ADDITIONAL CONVECTIVE
DEVELOPMENT WILL ALSO MOVE SOUTH THROUGH THE DAY...WITH SHOWERS
AND THUNDERSTORMS LIKELY TO OCCUR AT OR NEAR ALL OF THE TAF SITES.
THERE ARE STILL SEVERAL POSSIBLE SCENARIOS REGARDING THE TIMING OF
STORMS...THOUGH MID-DAY THROUGH EVENING SEEMS THE MOST LIKELY
POSSIBILITY.

BY SUNDAY NIGHT...WINDS WILL BEGIN TO SHIFT TO THE WEST AND THEN
WEST-NORTHWEST. THERE WILL CONTINUE TO BE A CHANCE OF OCCASIONAL
SHOWERS...ALTHOUGH STRONGER CONVECTION WILL BE LESS LIKELY AFTER
00Z.

OUTLOOK...THUNDERSTORMS ARE POSSIBLE FROM SUNDAY NIGHT INTO
MONDAY.

&&

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

&&

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





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