Area Forecast Discussion
Issued by NWS Wilmington, OH

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KILN 020811 AFDILN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 411 AM EDT THU JUL 2 2015 .SYNOPSIS... A STALLED FRONTAL BOUNDARY IS CURRENTLY LOCATED ALONG THE OHIO RIVER. AS LOW PRESSURE MOVES EAST ALONG THIS BOUNDARY TODAY...CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE. ADDITIONAL SHOWERS AND STORMS ARE EXPECTED FRIDAY...BUT HIGH PRESSURE WILL KEEP CHANCES MORE LIMITED OVER THE WEEKEND. TEMPERATURES WILL REMAIN SLIGHTLY BELOW NORMAL THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... BASED ON THE WPC SURFACE ANALYSIS...AND THETA-E PLOTS FROM RECENT NAM/RAP RUNS...IT APPEARS THAT THE STALLED SURFACE FRONT REMAINS STRETCHED WEST-TO-EAST SOMEWHERE IN THE VICINITY OF THE OHIO RIVER. THIS BOUNDARY IS UNLIKELY TO MOVE APPRECIABLY THROUGH THE END OF THE WEEK...BUT THE TRACK OF LOW PRESSURE ALONG THE FRONT WILL HAVE A SIGNIFICANT IMPACT ON THE WEATHER IN THE MIDDLE OHIO VALLEY. OF PARTICULAR INTEREST TODAY IS AN AREA OF SURFACE LOW PRESSURE...WHICH CURRENTLY SEEMS TO BE IN PLACE SOMEWHERE IN SOUTHERN MISSOURI. AHEAD OF THIS EASTWARD-MOVING LOW...CONVECTION HAS BEEN WIDESPREAD IN THE LOWER OHIO VALLEY...BUT SOME SCATTERED SHOWERS HAVE BEGUN MAKING THEIR WAY INTO THE ILN FORECAST AREA AS WELL. DISCOUNTING THE CHALLENGES WITH THE LOW TRACK TONIGHT AND FRIDAY...WHICH WILL BE DISCUSSED BELOW...CONFIDENCE HAS INCREASED IN THE OVERALL FORECAST SITUATION FOR TODAY. MOST OF THE MODELS NOW AGREE THAT FAIRLY WIDESPREAD PRECIPITATION WILL MOVE ACROSS SOUTHERN INDIANA AND KENTUCKY...COVERING ROUGHLY THE SOUTHERN THIRD OF THE NWS WILMINGTON FORECAST AREA WITH OCCASIONAL RAIN AND EMBEDDED CONVECTION. THE THREAT FOR STRONG STORMS LOOKS VERY LOW IN THE ILN CWA (NEAR AND NORTH OF THE BOUNDARY)...WITH VERY MARGINAL INSTABILITY AND NOTABLY WEAK WIND FLOW BELOW 500MB. HOWEVER...THE BOUNDARY COULD ACT AS A FOCUS FOR PROLONGED OR TRAINING SHOWERS AND STORMS...SO THERE MAY BE SOME POTENTIAL FOR MINOR FLOODING (AND IN AN AREA THAT HAS ALREADY SEEN QUITE A BIT OF RAIN IN THE PAST FEW DAYS). WITH THAT SAID...IT DOES NOT LOOK LIKE A SIGNIFICANT THREAT...AS HEAVIER RAINS ARE MORE LIKELY FURTHER SOUTH WHERE INSTABILITY IS GREATER. AFTER THE PEAK OF THE DIURNAL CYCLE...POPS WERE SIGNIFICANTLY LIMITED IN THE NORTHWESTERN HALF OF THE FORECAST AREA. HOWEVER...WEAK INSTABILITY AND THE PRESENCE OF THE SURFACE LOW WILL LIKELY KEEP A CHANCE OF SHOWERS OR STORMS IN THE SOUTHEASTERN CWA GOING INTO THE OVERNIGHT HOURS. TEMPERATURES WILL REMAIN BELOW NORMAL TODAY...WITH INCREASING CLOUDS AND THE COOL AIR MASS ALLOWING FOR VALUES AGAIN ABOUT 5-10 DEGREES BELOW NORMAL. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... MODEL DISAGREEMENT INCREASES BY FRIDAY REGARDING THE STRENGTH AND MOTION OF THE AREA OF LOW PRESSURE...AND THUS THE CONTINUED CHANCES FOR PRECIPITATION GOING INTO FRIDAY AND SATURDAY. LOOKING AT SURFACE PRESSURES AND 700/850MB HEIGHTS...THE GFS REMAINS THE SLOWEST AND FURTHEST NORTHWEST OF THE SOLUTIONS...AND THUS IT PRODUCES A SIGNIFICANT AMOUNT OF PRECIPITATION OVER OHIO ON FRIDAY AND EVEN INTO SATURDAY. THE NAM12 TRACK IS MUCH MORE PROGRESSIVE...WHILE A CMC/ECMWF COMPROMISE COMES NICELY IN BETWEEN. THIS ALLOWS FOR CONTINUED PRECIPITATION CHANCES ON FRIDAY (ESPECIALLY IN THE SOUTHEASTERN HALF OF THE FORECAST AREA) WITHOUT FORECASTING THE SIGNIFICANT QPF AMOUNTS MODELED BY THE GFS. PRECIPITATION CHANCES WILL DIMINISH A LITTLE FURTHER ON SATURDAY AS HIGH PRESSURE OVER THE SOUTHERN GREAT LAKES MOVES A LITTLE FURTHER SOUTH...AND SUPPORT FROM A WEAK SHORTWAVE DEPARTS THE REGION TO THE EAST. TEMPERATURES ON FRIDAY WERE KEPT IN THE MID TO UPPER 70S...WITH CLOUDS AND PRECIPITATION CHANCES AGAIN STUNTING THE DIURNAL RISE IN TEMPERATURES. WITH A LITTLE MORE SUN...VALUES SHOULD COME BACK INTO THE LOWER 80S ON SATURDAY. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... H5 VORT MAXIMA WILL BE DEPARTING OHIO VALLEY TO THE EAST TO START THE DAY SATURDAY BUT ANOTHER STRONGER H5 S/W AND VORT WILL CROSS THE GREAT LAKES REGION DURING THE DAY. NAM POPS CONVECTION OVER THE CWA BUT THIS IS NOT SUPPORTED BY SYNOPTIC MODELS AND AN UNFAVORABLE LOWER ATMOSPHERIC PROFILE WITH SFC HIGH PRESSURE BUILDING IN. BOTH THE SURFACE AND AN UPPER RIDGE BUILDS OVER THE REGION SUNDAY AND SOME MOISTURE TO THE SOUTHWEST OF THE SURFACE RIDGE MAY PERMIT STORMS DURING THE HEATING OF THE DAY OVER KY. SOUTHERLY FLOW KICKS IN OVERNIGHT SUNDAY AND CONTINUES UNTIL THE NEXT COLD FRONT CROSSES LATER TUESDAY. WHILE MONDAY DOES NOT APPEAR TO BE THE BEST DAY FOR CONVECTION TO FIRE...THE SOUTHERLY FLOW AND CLOSING PROXIMITY OF A COLD FRONT NECESSITATES LOW CHANCES FOR STORMS IN THE FORECAST. THE BREAKDOWN OF THE UPPER RIDGE AND DIURNAL HEATING ALSO SUPPORT INCLUSION OF POPS DURING THIS TIME. WHILE THERE ARE STILL SOME TIMING DIFFERENCES IT APPEARS THE COLD FRONT WILL CROSS THE OHIO VALLEY DURING PEAK HEATING TUESDAY AND THIS IS THE BEST CHANCES FOR STORMS IN THIS FORECAST PERIOD. MODEL GUIDANCE ON TEMPERATURES HAD VERY LITTLE VARIABILITY AND A BLEND WAS USED WITH THE EARLIER OFFICIAL FORECAST. RAISED TEMPS A BIT MONDAY NIGHT AHEAD OF THE FRONT IN THE WARM SECTOR...GENERALLY AROUND 70 BUT NOT QUITE AS WARM AS MEX GUIDANCE. TRENDING THAT DIRECTION AND THINK THE MEX NUMBERS ARE NOT UNREASONABLE IN THE LOWER 70S. HIGHS IN THE UPPER 70S TO LOWER 80S WILL BE SLIGHTLY BELOW CLIMO FOR MUCH OF THE AREA THROUGH THIS TIME. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... A STALLED OUR FRONTAL BOUNDARY WAS LOCATED WEST TO EAST ACROSS THE OHIO RIVER VALLEY THIS MORNING. EVEN AT THIS JUNCTURE...THERE CONTINUES TO BE VARYING SOLUTIONS ON HOW DIGGING MID LEVEL ENERGY WILL PERTURB A SURFACE LOW ALONG THE FRONTAL BOUNDARY. THIS INCLUDES HOW STRONG...HOW FAR NORTH...AND HOW LONG IT WILL TAKE TO RIPPLE EAST/SOUTHEAST. SHORT TERM HIGH RESOLUTION MODELS INDICATE THAT SHOWERS SHOULD BREAK OUT WELL AHEAD OF THE SURFACE WAVE FROM THE WEST TOWARD 12Z. THEREAFTER...THIS PCPN IS FORECAST TO MOVE EAST. GIVEN THE UNCERTAINTY OF HOW THE LOW WILL TRACK...THERE IS UNCERTAINTY ON HOW FAR NORTH THE PRECIPITATION SHOULD GET AND HOW LONG IT WILL LINGER INTO TONIGHT/TOMORROW. THE KCVG/KLUK/KILN TERMINALS LOOK TO HAVE THE BEST CHANCE FOR SHOWERS/MEASURABLE PRECIPITATION TODAY WHILE THE KDAY/KCMH/KLCK TAF SITES WILL BE ON THE EDGE. HAVE THEREFORE PLACED MVFR CONDITIONS AT KCVG/KLUK (HIGHEST CHANCE) AND VFR CONDITIONS ELSEWHERE. THERE WILL BE SOME ELEVATED INSTABILITY SO SOME EMBEDDED THUNDERSTORMS WILL BE POSSIBLE...WITH POCKETS OF MODERATE SHOWERS. WILL NOT PLACE TSRA IN THE TAFS AT THIS TIME AS THE COVERAGE SHOULD BE LOW AND SPORADIC FROM TIME TO TIME. HOWEVER...AVIATORS SHOULD BE AWARE THAT VISIBILITIES MAY TEMPORARY LOWER INTO THE IFR CATEGORY IN THE HEAVIER SHOWERS/STORMS. FOR TONIGHT...AS MENTIONED...THERE IS UNCERTAINTY ON THE LOW POSITION AND HOW FAST IT WILL TRACK EAST/SOUTHEAST. THUS...HAVE JUST KEPT SOME VCSH DESCRIPTORS FOR THE SOUTHERN TAF SITES. SINCE KCVG/KLUK SHOULD SEE THE MOST PROLONGED PERIOD OF HEAVIER RAIN...HAVE LOWERED THEIR CEILINGS TO BELOW 2000 FEET OVERNIGHT DUE TO BETTER ATMOSPHERIC SATURATION. OUTLOOK...THUNDERSTORMS POSSIBLE FRIDAY THROUGH MONDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...FRANKS AVIATION...HICKMAN

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.