Area Forecast Discussion
Issued by NWS Wilmington, OH

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000 FXUS61 KILN 311041 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 641 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/... 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 /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 /10Z 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...LATTO SHORT TERM...LATTO LONG TERM...BINAU AVIATION...JGL

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