Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 210019
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
819 PM EDT WED AUG 20 2014

.SYNOPSIS...
A FRONTAL ZONE WILL SETTLE INTO THE OHIO VALLEY THIS EVENING.
THIS FRONT WILL GRADUALLY LIFT NORTHEAST INTO THE GREAT LAKES
THROUGH THE WEEKEND. DISTURBANCES WILL INTERACT WITH A MOIST
AIRMASS TO PRODUCE SHOWERS AND THUNDERSTORMS AT TIMES THROUGH THE
PERIOD.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
CONVECTION THAT IS AFFECTING THE TRI-STATE REGION ATTM WASNT
HANDLED WELL BY THE MODELS. THE HRRR HAS TRIED TO DISSIPATE ALL
AFTERNOON. KEPT THE CONVECTION TOGETHER AND PUSHED IT THRU THE
OHIO RIVER COUNTIES LATE THIS AFTERNOON.

FIGURING OUT POPS FOR THE REST OF THE NIGHT IS TOUGH....SINCE THE
MODEL GUIDANCE DIDNT COVER THIS CURRENT CONVECTION WELL. THAT
MAKES IT HARD TO FIGURE OUT WHEN TO TRANSITION FROM THE RADAR TO
MODEL. DEVELOPED SOME PCPN IN THE TRI- STATE REGION BETWEEN
00-06Z ALONG A WEAK FRONT. THIS IS SIMILAR TO THE CMC/NAM
SOLUTION. THEN LET IT DISSIPATE AS FOCUS SHIFTS TO ENERGY TO OUR
NW.

LOWS TONIGHT WILL BE WARM AND MUGGY. TEMPERATURES WILL ONLY DROP INTO
THE UPPER 60S TO LOWER 70S.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
THERE IS A LARGE VARIATION IN MODEL SOLUTIONS FOR THURSDAY. PREFER
A NAM/CMC REGIONAL/HIRES-WRF SOLUTION WHICH DROPS H5 ENERGY INTO
THE REGION EARLY THURSDAY MORNING IN THE NW FLOW. THEY PUSH THE
BEST PCPN CHANCE ACROSS THE REGION DURING THE MORNING...AND EXIT
IT OUT OF THE EAST DURING THE AFTN.

THURSDAY NIGHT BETTER FORCING SHIFTS TO NRN OHIO AS CONVERGENCE
ALONG A LIFTING WARM FRONT MOVES ALSO. PUT HIGH CHANCE POPS IN THE
NORTHERN COUNTIES WITH DECREASING POPS DOWN TO THE SW.

ON FRIDAY...ADDITIONAL H5 ENERGY TOPS THE RIDGE AND DROPS SE
ACROSS THE REGION. THIS WILL HELP DEVELOP DAYTIME CONVECTION...BUT
CENTRAL OHIO WILL HAVE THE BEST CHANCE AT SEEING CONVECTION AS IT
IS CLOSER TO THE WARM FRONT.

CONVECTION TOMORROW WILL COMPLICATE THE HIGH TEMPERATURE FORECAST.
ONLY WENT LOWER 80S IN THE NW COUNTIES SINCE THE CONVECTION SHOULD
LIMIT HEATING THERE. SOUTHERN COUNTIES SHOULD BE ABLE TO MAKE THE
MID TO UPPER 80S. AFTER DROPPING DOWN TO ONLY AROUND 70 THURSDAY
NIGHT...FRIDAY IS LOOKING LIKE A HOT AND HUMID DAY. OHIO RIVER
COUNTIES SHOULD SEE TEMPERATURES PUSH INTO THE LOWER 90S WITH
DEWPOINTS IN THE LOWER 70S. THIS WILL PUSH HEAT INDICES OVER 100.
WILL CONTINUE TO HIGHLIGHT THE THREAT IN THE HWO.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
AT 12Z ON SATURDAY...THE 20.12Z ECMWF AND GFS ARE VERY GOOD
AGREEMENT ON THE LARGE SCALE PATTERN WITH AN AMPLIFIED FLOW PATTERN
OVER THE LOWER 48. A DEEP CLOSED LOW SHOULD BE OVER ID/MT WITH A
STRONG SUBTROPICAL RIDGE EXTENDING NORTHEAST FROM A 593DM HIGH OVER
ALABAMA. ANOMALOUS MOISTURE WILL STILL BE IN PLACE WITH PWAT FROM
1.5 TO 2.0 STANDARD DEVIATIONS ABOVE CLIMO. THROUGH THE WEEKEND THE
STRONG CLOSED LOW WILL SWING NORTHEAST INTO THE NRN HIGH PLAINS AND
EVENTUALLY INTO SASK...WHILE THE RIDGE EXPANDS NORTHEASTWARD INTO
TN/ARK. DESPITE WEAK FORCING...CONTINUED NORTHERLY/NORTHWESTERLY
FLOW AROUND THE RIDGE...THE PRESENCE OF A WEAK SURFACE TROUGH...AND
ANOMALOUS MOISTURE SHOULD CONTINUE TO ALLOW FOR STRONG DAYTIME
INSTBY BOTH SAT AND SUN. THE POTENTIAL FOR ONE MORE CLUSTERS OF SSE
PROPAGATING STORM CLUSTERS WILL CONTINUE THROUGH THE WEEKEND. GIVEN
THE MAGNITUDE OF INSTBY...EVEN WITH WEAKENING FLOW WITH TIME...THERE
COULD BE STRONG/SEVERE STORM THREAT ON EITHER OF THESE DAYS IF A
ORGANIZED COLD POOL COULD FORM. GETTING INTO MONDAY-TUESDAY...THE
RIDGE CONTINUES TO BUILD WITH HEAT/HUMIDITY. FLOW BECOMES VERY LIGHT
THROUGH THE BULK OF THE TROPOSPHERE AND IT BECOMES QUESTIONABLE IF
COVERAGE OF DAYTIME/EVE STORMS WARRANTS MENTION. RIGHT NOW HAVE RUN
15-25% RAIN CHANCES BOTH OF THESE DAYS...AND THAT MAY BE TOO HIGH.
INTO WEDNESDAY...SOME HINTS OF HEIGHT FALLS WHICH MAY ALLOW A LITTLE
STRONGER FLOW OR A WEAK SHORTWAVE TROUGH TO CROSS THE GREAT LAKES.
SO A BETTER STORM THREAT THEN...HOWEVER AT THIS TIME RANGE THIS IS A
VERY LOW CONFIDENCE FORECAST GIVEN CONDITIONAL NATURE OF THE RIDGE
BUCKLING.

SO ALL IN ALL...HAVE TENDED TO FOCUS RAIN CHANCES NEAR PEAK HEATING
INTO THE EVENING AND ALLOW FOR SOME DRY NIGHTS/EARLY MORNINGS. FLY
IN OINTMENT WILL BE ANY FORWARD PROPAGATING MCS THAT SURVIVES
THROUGH THE NIGHT...ORIGINATING TO OUR NORTHWEST  AND FALLING DOWN
NNWLY FLOW EITHER SATURDAY MORNING OR SUNDAY MORNING. LOW CONFIDENCE
STORM CHANCE...BUT HIGH CONFIDENCE WARM/HUMID PATTERN IS THE STORY
FOR THE SAT-WED TIMEFRAME.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
SHOWERS AND THUNDERSTORMS HAVE EXITED THE AREA AND EXPECT DRY
CONDITIONS ACROSS THE TAF SITES THIS EVENING AND FOR MOST OF THE
OVERNIGHT HOURS. A DISTURBANCE WILL APPROACH THE AREA LATE IN THE
OVERNIGHT HOURS AND INTO THE DAYTIME MORNING HOURS ON THURSDAY.
HAVE A VCTS MENTION AT ALL TAF SITES FOR AWHILE DURING THIS TIME.
ADDED IN A TEMPO TSRA MENTION AT ALL AREA TAF SITES EXCEPT KCVG
AND KLUK.

THERE IS SOME QUESTION ON HOW LONG THE SHOWERS AND THUNDERSTORMS
WILL LINGER INTO THE AFTERNOON AND IF THERE WILL BE ADDITIONAL
DEVELOPMENT. EXPECT ANY ADDITIONAL DEVELOPMENT TO EXIT THE TAF
SITES BY THE END OF THE TAF PERIOD.

ADDITIONAL PRECIPITATION WILL START TO WORK INTO THE KCVG TAF AT
THE END OF THAT TAF PERIOD DUE TO THE LONGER TAF PERIOD. IN
ADDITION SOME FOG WILL BE POSSIBLE AT KCVG AND KLUK OVERNIGHT DUE
TO THE PREVIOUS RAINFALL AT THOSE LOCATIONS.

OUTLOOK...THUNDERSTORMS POSSIBLE THURSDAY EVENING THROUGH
SUNDAY.

&&

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

&&

$$
SYNOPSIS...SITES/SNYDER
NEAR TERM...SITES
SHORT TERM...SITES
LONG TERM...BINAU
AVIATION...NOVAK






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