Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 260812 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 412 AM EDT SAT JUL 26 2014 .SYNOPSIS... UPPER LEVEL LOW WITH DISTURBANCES IN THE FLOW THROUGH TONIGHT. COLD FRONT WITH STRONG STORMS SUNDAY. LINGERING CONVECTION IN THE UPPER LEVEL LOW THROUGH MONDAY. COOLER AIRMASS SETTLES IN PLACE THROUGH MID WEEK. && .NEAR TERM /THROUGH TONIGHT/... MODELS ARE IN GOOD AGREEMENT ON A VIGOROUS SHORT WAVE APPROACHING FROM THE WEST TONIGHT...WITH A WELL DEFINED WARM FRONT FOR THIS TIME OF YEAR LIFTING NORTH AND EAST TOWARD OUR AREA. GIVEN THE STRENGTH OF THE DYNAMICS AND A MODERATE 850 MB SOUTHWESTERLY JET FEEDING WARM AND QUITE MOIST AIR NORTHWARD...THE MODELS TARGET THE BEST COMBINATION OF THESE PARAMETERS RIGHT ACROSS OUR AREA...MAINLY LATER TONIGHT IN THE FORM OF AN MCS. WITH HPC AND SPC ALSO TARGETING OUR AREA WITH A RISK FOR BOTH SEVERE STORMS AND EXCESSIVE RAINFALL...HAVE TO GO WITH THIS SCENARIO. THIS BRINGS CAT POPS FROM THE WEST AND NORTHWEST ACROSS OUR AREA TONIGHT...AGAIN MAINLY AFTER MIDNIGHT. HOWEVER...OF SOME CONCERN IS THE EFFECTS OF A STILL NORTHWESTERLY COMPONENT OF THE 1000-5000 MB THICKNESS FIELDS...WHICH MAY PULL THE ANTICIPATED COMPLEX FORMING WELL UPSTREAM LATER TODAY MORE SOUTHEASTWARD INTO KENTUCKY. AT THIS POINT THOUGH...FROM ALL THAT IS MENTIONED ABOVE...CONFIDENCE IS NOT HIGH ENOUGH TO DEVIATE FROM GUIDANCE. WILL MENTION THESE CONCERNS IN THE HAZARDOUS WEATHER PRODUCT FOR NOW...UNTIL WE GET MORE CONFIDENCE IN THE EVOLUTION OF THINGS TODAY BEFORE ANY WATCHES ARE CONSIDERED. OH YES...ABOUT TODAY. TODAY WILL BE THE TRANSITION TO THE SETUP FOR TONIGHT. SURFACE HIGH PRESSURE SHIFTING FARTHER OFF TO THE EAST WILL ALLOW STRONG WARM AND MOIST ADVECTION ON INCREASING SOUTHWESTERLY FLOW. EARLY MORNING UPPER DISTURBANCE WITH THE WIDESPREAD MID CLOUDS WILL LIFT OUT BY MID MORNING...BEING REPLACED BY A SCATTERED CU FIELD THIS AFTERNOON WITH LACK OF UPPER DISTURBANCES. THUS...KEEPING THINGS DRY BUT MUCH WARMER AND MORE HUMID TODAY UNDER A GOOD DEAL OF SUNSHINE. GOING ON THE WARMER SIDE OF GUIDANCE WITH HIGHS APPROACHING 90 DEGREES. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... BEST PLACE TO START WITH THIS FORECAST IS THE MODERATE RISK FROM SPC IN THE MIDDLE OHIO VALLEY AND CENTRAL APPALACHIANS FOR SUNDAY INTO SUNDAY NIGHT. ALSO HAVE THE POTENTIAL FOR EXCESSIVE RAINFALL. UPPER LEVEL LOW WILL DIVE INTO TH GREAT LAKES FROM THE NORTHERN PLAINS LATE THIS WEEKEND WITH YET ANOTHER DYNAMIC SYSTEM. WILL LIKELY BE DEALING WITH A LATE NIGHT MCS TOWARDS THE BEGINNING OF THE SHORT TERM FORECAST BRINGING A WIND THREAT. THIS COULD WORK TO DESTABILIZE THE ATMOSPHERE LATER IN THE DAY WITH COOLING TO THE MID LEVELS AS THE SURFACE RECOVERS UNDER SOLAR INSOLATION...THUS INCREASING THE LOW AND MID LEVEL LAPSE RATES INTO THE LATE AFTERNOON AND EVENING SUNDAY. STORMS WILL FORM ALONG THE STRONG COLD FRONT AND PROPAGATE RAPIDLY WITH AN OBVIOUS WIND THREAT AS WELL AS LARGE HAIL. AS THE SPEED SHEAR INCREASES WITH THE APPROACHING OF THE UPPER LEVEL LOW...SO DOES THE DIRECTIONAL SHEAR OVER THE LOW LEVELS...AND WILL SEE SOME VEERING WITH HEIGHT. RAPID DRYING ALOFT ABOVE 700MB OCCURS AFTER 00Z MONDAY...BUT AS THE UPPER LOW ROTATES INTO LAKE ERIE...ANOTHER AXIS OF MOISTURE WILL DROP IN FROM THE NORTH. THIS KEEPS THE POPS GOING AFTER A SHORT REPRIEVE INTO THE MONDAY TIME FRAME. IN THE END...THIS COLD FRONTAL PASSAGE WILL BRING YET ANOTHER SIGNIFICANT CHANGE IN AIRMASS...IN A JULY THAT HAS SEEN A STEADY DOSE OF THESE COLD FRONTS THAT HAVE USHERED IN INFLUENCES FROM CANADIAN HIGH PRESSURE. MAX TEMPERATURES WILL BE BACK DOWN AROUND 10 TO 15 DEGREES BELOW NORMAL. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... HIGH PRESSURE BEHIND THE COLD FRONT TAKES CONTROL LATER MONDAY NIGHT THROUGH THE MIDDLE OF NEXT WEEK WITH NEAR NORMAL TEMPERATURES. BLENDED HPC WITH PREVIOUS FORECAST NUMBERS AS THEY LOOK REPRESENTATIVE UNDER HIGH PRESSURE AND SLIGHTLY COOLER NORTHERLY FLOW. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... 06Z SATURDAY THRU 06Z SUNDAY... UPPER LEVEL DISTURBANCE OVERNIGHT WILL CONTINUE VFR CEILINGS AOA 8000 FEET. THIS WILL LIMIT FOG TO SCATTERED MVFR RIVER AND VALLEY FOG 08Z TO 12Z. AFTER 12Z...BECOMING SCATTERED CU WITH HEATING AS UPPER DISTURBANCE LIFTS OUT. THUNDERSTORM COMPLEX WILL BEGIN TO AFFECT AREA AFTER 03Z FROM THE NORTHWEST...AND MAY REACH JUST PAST OHIO RIVER AROUND 06Z. GREAT UNCERTAINTY ABOUT THE DEVELOPMENT AND TRACK OF THIS EXPECTED COMPLEX ALONG WITH THE LATENESS OF THE POTENTIAL EVENT...LEADS A TAF FORECAST TO BRING MVFR CONDITIONS WITH SHOWERS AND SCATTERED STORMS TO PKB ONLY AND JUST SHY OF HTS BY 06Z. THE REMAINDER OF THE TERMINAL SHOULD REMAIN PRECIP FREE THRU 06Z. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z SUNDAY... FORECAST CONFIDENCE: HIGH TODAY...LOW TONIGHT. ALTERNATE SCENARIOS: TIMING...COVERAGE AND DENSITY OF FOG OVERNIGHT COULD VARY DEPENDING ON CLOUD COVER. THUNDERSTORM COMPLEX OVER AREA SATURDAY NIGHT IS UNCERTAIN. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE SAT 07/26/14 UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19 EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15 CRW CONSISTENCY H H H H H H H H H H H H HTS CONSISTENCY H H H H H H H H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H H CKB CONSISTENCY H H H H H H H H H H H H AFTER 06Z SUNDAY... IFR POSSIBLE IN ROUNDS OF CONVECTION SATURDAY NIGHT INTO SUNDAY NIGHT. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JMV/26 NEAR TERM...JMV SHORT TERM...26 LONG TERM...ARJ AVIATION...JMV

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