Area Forecast Discussion
Issued by NWS Wilmington, OH

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000
FXUS61 KILN 311457
AFDILN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
1057 AM EDT THU JUL 31 2014

.SYNOPSIS...
A PERSISTENT TROUGH WILL REMAIN ACROSS THE REGION THROUGH THE
WEEKEND. INCREASING MOISTURE WILL BRING CHANCES FOR SHOWERS AND
THUNDERSTORMS TO THE AREA OVER THE WEEKEND...MAINLY DURING THE
DAYTIME.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WEAK SURFACE HIGH SHOULD KEEP MUCH OF THE REGION DRY THIS
AFTERNOON. SKIES WILL BECOME MOSTLY SUNNY TO PARTLY CLOUDY AS
DIURNAL CUMULUS CLOUDS ARE EXPECTED. IF A SMALL POP UP SHOWER OR
STORM SHOULD OCCUR...IT MOST LIKELY BE NEAR OUR NW ZONES GIVEN
THE CLOSER PROXIMITY TO A WEAK EMBEDDED DISTURBANCE MOVING THROUGH
NRN INDIANA...SRN MICHIGAN...AND NORTHWEST OHIO THIS AFTERNOON.

TEMPERATURES WILL BE A FEW DEGREES WARMER TODAY THAN YESTERDAY...WITH
HIGHS PEAKING MOSTLY IN THE LOWER 80S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
HIGH PRESSURE WILL RESIDE TO THE EAST OF OUR AREA WITH A TROUGH
ACROSS OUR REGION BECOMING POSITIVELY TILTED WITH THE TROUGH AXIS
JUST TO OUR WEST. THIS WILL LEAVE OUR AREA WITH LOW LEVEL SOUTHERLY
FLOW AND SOUTHWESTERLY FLOW ALOFT TONIGHT THROUGH SATURDAY. THE
RESULT WILL BE AN INCREASE IN MOISTURE ACROSS THE AREA. THIS
INCREASE IN MOISTURE WILL ALLOW FOR AN UPTICK IN SHOWER AND
THUNDERSTORM ACTIVITY BOTH FRIDAY AND SATURDAY AFTERNOON AND
EVENING. AT THIS TIME IT APPEARS THE BETTER COVERAGE OF CONVECTION
WILL BE SATURDAY AFTERNOON.

TEMPERATURES ARE EXPECTED TO CONTINUE TO RUN A FEW DEGREES BELOW
NORMAL OVER THE WEEKEND DUE TO OUR CLOSE PROXIMITY TO THE
PERSISTENT TROUGH.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AT 12Z FRIDAY /01.12Z/ -- DEEP ERN CONUS LONGWAVE TROUGH REMAINS
INTACT IN A HIGHLY AMPLIFIED NORTHERN HEMISPHERE FLOW PATTERN
CONSISTING OF A STRONG ATLANTIC RIDGE...THE ERN CONUS
TROUGH...STRONG WRN CONUS RIDGE...AND DEEP CLOSED LOW OVER PACIFIC
WATERS SOUTH OF ALASKA. ACCORDING TO 30.12Z GFS/ECMWF
DETERMINISTIC RUNS...A TRIO OF MIDLEVEL VORTICITY MAXIMUMS
ROTATING DOWN THE WEST SIDE OF THE DEEP CLOSED LOW NEAR HUDSON BAY
AND RISING HEIGHTS IN THE ATLANTIC OCEAN WILL FORCE THE L/W TROUGH
AXIS IN THE ERN CONUS TO RETROGRADE/REFOCUS BACK TO THE WEST OVER
THE OH VALLEY FRI/SAT...WITH MIDLEVEL FLOW BACKING WITH TIME. IN
FACT BY SATURDAY...A DEEPER SWLY MID/UPPER FLOW FIELD WILL
OVERSPREAD THE OHIO VALLEY AS THE TROUGH AXIS REFORMS TO THE WEST.
THESE FORCING MECHANISMS WILL ACT TO RECARVE/SHARPEN THE TROUGH
DURING THIS TIME PERIOD...INDUCING SUBTLE SYNOPTIC SCALE LIFT AND
THE ORGANIZING TROUGH BEGINS TO SHIFT EAST ACROSS THE AREA ON SAT
EVENING. WHILE LOWER LEVEL WIND FIELDS WILL REMAIN VERY WEAK /NOT
MUCH SURFACE REFLECTION OF THESE SYNOPTIC SCALE PROCESSES/ THERE
WILL BE MODEST MOISTURE AND TEMPERATURE RISES THAT OCCUR FRI/SAT
WHICH WILL CONTINUE TO FOSTER AN UNSETTLED/UNSTABLE
ATMOSPHERE...WITH BEST COVERAGE OF DIURNALLY-ENHANCED
SHOWERS/STORMS ON SATURDAY AS A WEAK INVERTED TROUGH TRIES TO
DEVELOP ACROSS THE AREA FROM WEAK LOW PRESSURE IN TN/KY.

UNCERTAINTY ON HOW FAST THE TROUGH AXIS SHIFTS EAST...SEEING TWO
IDEAS IN THE DATA...ONE IN WHICH THE AXIS LINGERS OVER OHIO/KY
THROUGH SUNDAY AND A MORE PROGRESSIVE SOLUTION /30.12Z ECMWF/ WHICH
SHUNTS THE AXIS EAST INTO PA ON SUNDAY. THE LATTER WOULD YIELD A
DRIER SUNDAY - THE FORMER STILL SOME LINGERING DIURNAL
SHOWERS/STORMS. PLAYING CONTINUITY FROM PREVIOUS FORECAST AND INPUT
FROM HPC WILL KEEP LOWER RAIN CHANCES IN ON SUNDAY...MAINLY IN CNTL
OH/SCIOTO VALLEY.

RUNNING WITH A DRY SUN NIGHT/MON/MON NIGHT IN WAKE OF THIS FEATURE
PUSHING EAST OF THE AREA AND NONDESCRIPT/WEAK FLOW PATTERN ABSENT OF
ANY WAVES. TUES/WED...GLANCING BLOW FROM ENERGY MOVING THROUGH SERN
CANADA MAY PUSH WEAK FRONTAL ZONE INTO OHIO/IND THESE DAYS WITH
SMALL CHANCE OF STORMS ALONG THE FRONT TUES AFTN INTO WED AMIDST
VERY WEAK HEIGHT FALLS. AGAIN...SMALL RAIN CHANCES BUT MOST AREAS
LIKELY REMAINING DRY...AND WARMER...AS NEGATIVE HEIGHT/TEMP
ANOMALIES WILL FINALLY HAVE BEEN PUSHED EAST/NORTHEAST ON FLATTENING
OVERALL HEMISPHERIC FLOW.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
SKIES HAVE CLEARED OFF ACROSS THE AREA THIS MORNING AND THIS HAS
ALLOWED FOR SOME PATCHY MVFR TO LOCALLY IFR FOG TO
DEVELOP...ESPECIALLY IN THE SOUTHERN RIVER VALLEYS. ANY FOG SHOULD
QUICKLY BURN OFF IN THE FIRST HOUR OR SO OF THE TAF PERIOD WITH
SCT CU DEVELOPING FROM LATE MORNING INTO EARLY AFTERNOON. SOME
WEAK INSTABILITY IS PROGGED TO DEVELOP THROUGH THE AFTERNOON HOURS.
HOWEVER...WITH AN OVERALL LACK OF FORCING...ANY SHOWER ACTIVITY
SHOULD BE ISOLATED AT BEST. DIURNAL CU WILL DISSIPATE BY THIS
EVENING WITH MAINLY CLEAR SKIES EXPECTED OVERNIGHT. THIS WILL
ALLOW FOR SOME MVFR TO LOCALLY IFR FOG DEVELOPMENT...WITH AN
EMPHASIS AGAIN IN THE SOUTHERN VALLEYS...INCLUDING KLUK.

OUTLOOK...THUNDERSTORMS POSSIBLE FRIDAY THROUGH SUNDAY.

&&

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

&&

$$
SYNOPSIS...LATTO
NEAR TERM...HICKMAN/LATTO
SHORT TERM...LATTO
LONG TERM...BINAU
AVIATION...JGL






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