Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 310537 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 137 AM EDT THU JUL 31 2014 .SYNOPSIS... A PERSISTENT TROUGH WILL REMAIN ACROSS THE REGION INTO EARLY NEXT WEEK. THIS WILL PROVIDE NEAR TO BELOW NORMAL TEMPERATURES ACROSS THE OHIO VALLEY. AFTERNOON SHOWER AND THUNDERSTORM ACTIVITY WILL REMAIN POSSIBLE THROUGH THIS TIME...GENERALLY ENDING BY THE EVENING && .NEAR TERM /UNTIL 6 AM THIS MORNING/... STILL SOME LINGERING SHOWERS/ISOLATED TSTMS WITH THE DEPARTING S/WV...AND ALONG A CONVERGENT BOUNDARY EXTENDING ROUGHLY FROM ILN/DAY/IND. AS MORE WIDESPREAD ACTIVITY DEPARTS FCST AREA...LINGERED ISOLATED SHOWERS ALONG THIS BOUNDARY AND DIMINISHING BY MIDNIGHT. SECONDARY S/WV OVER SOUTHERN WI DROPPING DOWN OVERNIGHT...BUT CONTINUING THE THINKING THAT ANY ASSOCIATED ACTIVITY WILL REMAIN NORTH OF FCST AREA. TEMPERATURES WILL DROP TO THE UPPER 50S WITH CLEARING SKIES TONIGHT. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/... SIMILAR PATTERN IS IN THE OFFING FOR TOMORROW BUT THERE SHOULD BE A LACK OF MID LEVEL SHORTWAVES ROTATING THROUGH THE REGION. THEREFORE...KEPT THE CHANCE OF PRECIPITATION OUT OF THE FORECAST ATTM BUT WOULD NOT ARGUE THAT AN ISOLATED SHOWER IS NOT OUT OF THE QUESTION. HIGHS WILL RISE A FEW DEGREES MORE TOMORROW...UPPER 70S NORTH LOWER 80S SOUTH AND OVERNIGHT LOWS WILL ALSO RISE A SIMILAR AMOUNT AND ONLY DROP TO AROUND 60 OR IN THE LOWER 60S. && .LONG TERM /FRIDAY 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 /06Z THURSDAY THROUGH MONDAY/... A PERSISTENT LOW LEVEL CONVERGENT BOUNDARY HAS HELPED KEEP SCATTERED SHOWERS AND A FEW EMBEDDED THUNDERSTORMS GOING FROM EAST CENTRAL INDIANA INTO CENTRAL OHIO EARLY THIS MORNING. THIS CONVERGENT BOUNDARY IS FORECAST TO SAG SLOWLY SOUTH AND WEAKEN THROUGH 12Z SO EXPECT TO SEE A GRADUAL WEAKENING/DISSIPATING TREND THROUGH DAYBREAK. OTHERWISE...WE COULD STILL SEE SOME AREAS OF FOG THROUGH DAYBREAK BUT THIS MAY BE MITIGATED SOMEWHAT BY SOME OF THE CLOUDS THAT ARE STILL LINGERING ACROSS THE REGION. WE SHOULD CU UP ONCE AGAIN LATER THIS MORNING AND ON INTO THIS AFTERNOON AS WEAK DIURNAL INSTABILITY REDEVELOPS ACROSS THE AREA. SUPPOSE AN ISOLATED SHOWER OR THUNDERSTORM IS NOT OUT OF THE QUESTION...BUT THERE IS NOT MUCH LEFT IN THE WAY OF FORCING SO WILL KEEP THE TAFS DRY THIS AFTERNOON. OUTLOOK...THUNDERSTORMS POSSIBLE FRIDAY THROUGH SUNDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...FRANKS NEAR TERM...JDR SHORT TERM...FRANKS LONG TERM...BINAU AVIATION...JGL

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