Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 310701 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 301 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 /THROUGH TODAY/... SHORTWAVE SHIFTING EAST OF THE AREA THIS MORNING WILL RESULT IN A END TO SHOWER ACTIVITY. WEAK HIGH PRESSURE AND SUBSIDENCE IN THE WAKE OF THE DEPARTING SHORTWAVE IS EXPECTED TO KEEP OUR AREA FREE OF CONVECTION TODAY. TEMPERATURES WILL BE A FEW DEGREES WARMER TODAY THAN YESTERDAY...WITH HIGHS REACHING THE UPPER 70S TO LOWER 80S. && .SHORT TERM /TONIGHT 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 /07Z 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...LATTO NEAR TERM...LATTO SHORT TERM...LATTO LONG TERM...BINAU AVIATION...JGL

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