Area Forecast Discussion
Issued by NWS Charleston, WV

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000 FXUS61 KRLX 260605 AFDRLX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 147 AM EDT SAT JUL 26 2014 .SYNOPSIS... A SERIES OF DISTURBANCES AHEAD OF A STRONG COLD FRONT WILL BRING ROUNDS OF CONVECTION MAINLY SATURDAY NIGHT THRU SUNDAY NIGHT. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... CLOUDS ARE COMING IN A BIT FASTER THAN MODELS INDICATED. THEREFORE...WILL UPDATE SKY COVER THIS EVENING ACCORDINGLY. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/... SURFACE SOUTHERLY FLOW AND WESTERLY ALOFT WILL BRING MODEST WARM AIR ADVECTION TO THE REGION SATURDAY NIGHT INTO SUNDAY. WINDS AT H85 BECOME ABOUT 45 KNOTS OUT OF THE SOUTHWEST AHEAD OF AN APPROACHING COLD FRONT. A BROAD UPPER LEVEL LOW PRESSURE SYSTEM CENTERED NORTH OF THE GREAT LAKES REGION EXTENDS SOUTH WITH A SERIES OF VORTICITY LOBES NOTICED AT H5 PASSING OVER OH VALLEY AND WV. THE FIRST AND WEAKER WAVE MOVES THROUGH OVERNIGHT HOURS OF SATURDAY NIGHT. THE SECOND BUT STRONGER VORTICITY MAXIMA MOVES ACROSS DURING THE DAY SUNDAY WITH ADDITIONAL VORTICITY LOBES PASSING THROUGH MONDAY. MODELS ARE IN DESCENT AGREEMENT WITH THE TIMING OF CONVECTION REACHING OR DEVELOPING OVER OUR AREA...ALTHOUGH SUBTLE DIFFERENCES ARE NOTICED ON THE LOCATION OF THE STRONGEST PCPN. THE GFS AND ECMWF SHOW THE ARRIVAL OF TWO MID LEVEL WAVES...ONE APPROACHING SOUTHEAST OH BY 00Z AND THE SECOND BY 06Z SUNDAY. SFC BASED CAPE INCREASES TO 1800 J/KG BY 12Z SUNDAY...AND EXCEEDING 2500 J/KG SUNDAY AFTERNOON ACROSS THE TRI STATE AREA...EXTENDING NORTHEAST ACROSS WV AND SOUTHEAST OH. MODELS SUGGEST DEEP LAYERED SHEAR EXCEEDING 60 KNOTS AND PWATS AROUND 2 INCHES SUNDAY AFTERNOON. HELICITY VALUES EXCEED 300 M2/S2 BY THE SAME TIME PERIOD. THESE INGREDIENT ARE FAVORABLE FOR STORMS TO BECOME SEVERE WITH THERMODYNAMIC AND DYNAMIC INSTABILITY. CONSEQUENTLY...THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS ACROSS SOUTHEAST OH...NORTHEAST KY AND ALL OF WV FOR SUNDAY. WITH GOOD CONSENSUS AMONG SYNOPTIC MODELS AND SREF INDICATING 60 PERCENT POPS MAINLY ACROSS THE NORTHERN THIRD OF OUR CWA...CONFIDENCE HAS INCREASED AND DECIDED TO INCREASE POPS AS WELL FOR SUNDAY. MENTIONED DAMAGING WINDS AND HAIL IN THE WEATHER GRIDS ALONG WITH HEAVY RAIN PER THE AFOREMENTIONED PARAMETERS. IN ADDITION...HPC HAVE PORTIONS OF SOUTHEAST OH...NORTHEAST KY AND THE ENTIRE AREA OF WV UNDER HIGH PROBABILITY OF EXCESSIVE RAINFALL. BACKWARD CORFIDI VECTOR MAGNITUDE INCREASE CONSIDERABLY ON SUNDAY AFTERNOON. WITH PWATS RANGING AROUND 2 INCHES...AND THE NATURE OF THE SEVERE THUNDERSTORMS...WATER PROBLEMS MAY RESULT WITH REPETITIVE PERIODS OF HEAVY RAINFALL. A FLASH FLOOD WATCH MAY BE REQUIRED FOR SUNDAY AND EARLY MONDAY. LINGERING SHOWERS OR STORMS CAN NOT BE RULED OUT SUNDAY NIGHT INTO MONDAY AS THE BROAD UPPER LOW CONTINUES TO PUSH VORTICITY MAXIMA ACROSS THE AREA. CODED LOW CHANCE POPS FOR SUNDAY NIGHT INTO MONDAY. DESPITE OF WARM AIR ADVECTION ALOFT...EXPECT MILD TEMPERATURES DUE TO CLOUD COVER AND COOLING SHOWERS EFFECTS. WENT GENERALLY WITH THE CONSENSUS MOS GUIDANCE WITH SOME TWEAKS. KEPT WARMER TEMPS FOR A MUGGY SUNDAY NIGHT. LOW TURN NORTHWEST BY MONDAY BRINGING COOLER PLEASANT TEMPERATURES DURING THE FIRST HALF OF THE WEEK. CONDITIONS IMPROVE MONDAY AND MONDAY NIGHT. AS THE COLD FRONT EXITS...WITH PRECIP DECREASING FROM WEST TO EAST AND MUCH COOLER TEMPERATURES OVERSPREADING THE AREA.&& .LONG TERM /MONDAY 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 /06Z 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 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 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 M M 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...ARJ/JMV/50 NEAR TERM...RPY SHORT TERM...ARJ LONG TERM...ARJ AVIATION...JMV

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