Area Forecast Discussion
Issued by NWS Newport/Morehead, NC

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000 FXUS62 KMHX 220807 AFDMHX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 407 AM EDT FRI AUG 22 2014 .SYNOPSIS... A SERIES OF SHORTWAVES WILL CROSS THE AREA GIVING WAY TO UNSETTLED WEATHER OVER THE NEXT COUPLE DAYS. MEANWHILE...A BACKDOOR COLD FRONT WILL SAG SOUTH OF THE REGION THROUGH THE WEEKEND. && .NEAR TERM /TODAY/... AS OF 330 AM FRIDAY...WITH A TROUGH TO THE EAST AND RIDGING SET TO THE WEST...EASTERN NC HAS BEEN UNDER PERSISTENT NW FLOW ALOFT. THIS WILL STREAM ANOTHER BATCH OF MID/UPPER LEVEL DISTURBANCES ACROSS THE REGION THROUGH THE PERIOD. THE FIRST BEING AN UPPER LEVEL SHORTWAVE MOVING OFFSHORE WITH LINGERING SCHC SHOWER/THUNDERSTORMS DURING THE MORNING HOURS. THE NEXT IMPULSE WILL BE APPROACHING FROM THE NW BY EARLY AFTERNOON. CURRENTLY AN MCS MIGRATING ACROSS THE OHIO RIVER VALLEY WILL CROSS THE VA MOUNTAINS TOWARD EASTERN NC BY MID-DAY. THE TIMING OF THIS NEXT SYSTEM WILL MAKE ALL THE DIFFERENCE IN TERMS OF THE SEVERE POTENTIAL AND PRECIPITATION TIMING DURING THE AFTERNOON INTO THE OVERNIGHT PERIOD. WITH TEMPS CLIMBING INTO THE LOW/MID 90S INLAND AND POTENTIAL BREAKS IN THE CLOUDS DURING THE DAY...INSTABILITY WILL BE ON THE RISE. IF THE SHORTWAVE IS ABLE TO CROSS THE VA MOUNTAINS AND ARRIVE DURING PEAK HEATING THAN WE WILL LIKELY HAVE ENOUGH INITIATION FOR ISOLATED STRONG TO SEVERE THUNDERSTORMS ACROSS THE REGION. WITH UPPER LEVEL DIVERGENCE...MID LEVEL SHORTWAVE AND SFC INSTABILITY (MUCAPE NEARING 3 J/KG AND 25KTS SHEAR)...THIS COULD MAKE FOR ORGANIZED THUNDERSTORMS MOVING FROM THE NW TO THE SE THROUGH THE AFTERNOON/EVENING HOURS. THE STORMS WILL BE MOVING AT A PRETTY GOOD PACE WITH THE MAIN THREAT BEING DAMAGING WIND. HOWEVER...IT SHOULD BE NOTED THAT THE MCS MAY REQUIRE REDEVELOPMENT IF THE MOUNTAINS IMPACTED THE ORGANIZED CONVECTION. IF THIS OCCURS...THAN WE WILL LIKELY SEE MORE ACTIVITY GETTING INTO THE EVENING/OVERNIGHT PERIOD. GIVEN SUCH UNCERTAINTY...HAVE CHC SHOWER/THUNDERSTORM ACTIVITY THROUGH FRIDAY WITH THE MORE LIKELY SCENARIO FAVORED FOR A LATER ARRIVAL OF THE SHORTWAVE. && .SHORT TERM /TONIGHT/... AS 330 AM FRIDAY...THE CONVECTION ASSOCIATED WITH A POTENT SHORTWAVE WILL EITHER BE CROSSING THE REGION AND EXITING OFFSHORE...OR REDEVELOPING DURING THE START OF THE PERIOD. CURRENTLY FEEL THE SHORTWAVE WILL APPROACH FRIDAY EVENING AND EXIT OFF THE NC/VA COAST OVERNIGHT....WITH MUCH OF THE PRECIPITATION ON GOING THROUGH EARLY AM. A BACKDOOR COLD FRONT ASSOCIATED WITH THE SHORTWAVE WILL MOVE THROUGH THE AREA BY EARLY SATURDAY MORNING. WHILE SFC INSTABILITY WILL BE WANING AFTER PEAK HEATING...THERE IS STILL AMPLE UPPER/MID LEVEL LIFT TO HAVE CHC SHOWER/THUNDERSTORMS MOVING THROUGH DURING THE PERIOD. WITH PLENTY OF CLOUD COVER IN PLACE TEMPS WILL BE IN THE LOW/MID 70S INLAND TO MID 70S ALONG THE COAST. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 355 AM FRIDAY...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE SAT INTO SAT EVENING AS A COLD FRONT SLOWLY PUSHES S THROUGH THE REGION AND SHORTWAVES CROSS IN NW FLOW ALOFT. DIFFICULT TO PINPOINT WHERE BEST PRECIP CHANCES WILL BE AND WHEN IT WILL OCCUR GIVEN THE DIFFICULTY IN TIMING INDIVIDUAL SHORT WAVE ENERGY/VORTICITY MAXIMA SO WILL MAINTAIN HIGH CHANCE POPS FOR MUCH OF THE AREA THROUGH SAT EVENING. AS NE FLOW DEVELOPS IN WAKE OF FRONT LATE SAT WILL SEE TEMPS HOLD IN THE 80S WITH SOME SOUTHWESTERN ZONES APPROACHING 90F. SURFACE FRONT WILL DRIVE SOUTH ALONG THE SE U.S. COAST SUN AND STALL WELL SOUTH OF THE AREA EARLY NEXT WEEK. A DRIER NW UPPER FLOW AND SURFACE HIGH PRESSURE TO THE NE BUILDING DOWN THE MID ATLANTIC COAST SHOULD LEAD TO REDUCED PRECIP CHANCES SUNDAY INTO MONDAY, SO HAVE MAINTAINED SLIGHT CHANCE POPS FOR INLAND AREAS TO COINCIDE WITH FAVORABLE DIURNAL CYCLES. ATYPICAL ONSHORE FLOW FOR AUGUST WILL LEAD TO SLIGHTLY BELOW NORMAL MAX TEMPS SUN/MON...MAINLY LOW TO MID 80S. FOR THE EXTENDED FORECAST PERIOD...MODEL CONSENSUS SUGGESTS A BUILDING OF THE MIDWEST UPPER RIDGE TOWARD THE EAST COAST AS SURFACE HIGH PRESSURE REMAINS CENTERED TO THE NORTH. THIS SHOULD LEAD TO A MAINLY DRY MID WEEK. TEMPS WILL REMAIN BELOW NORMAL EARLY IN THE WEEK THEN BEGIN TO MODERATE BACK TO NEAR OR SLIGHTLY ABOVE NORMAL DURING MIDWEEK. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... SHORT TERM /THROUGH 06Z SATURDAY/... AS OF 1 AM FRIDAY...VFR CONDITIONS EXPECTED THROUGH MUCH OF THE PERIOD. HOWEVER...ANTICIPATE SOME MVFR VSBYS OVERNIGHT AS WINDS CALM AND WE HAVE SOME BREAKS IN THE CLOUDS. ANTICIPATE SOME HIGH/MID LEVEL CLOUDS MOVING THROUGH FRIDAY MORNING AS THE NEXT IMPULSE APPROACHES THE AREA. WINDS WILL PICK UP AFTER SUNRISE FROM THE WEST. COULD BE AN ACTIVE AFTERNOON WITH CONVECTION. THE TIMING AND LOCATION IS STILL IN QUESTION. THIS ACTIVITY MAY CONTINUE THROUGH FRIDAY NIGHT. SO GIVEN THE UNCERTAINTIES...HAVE VCTS AFTER 18Z FOR ALL AREA TAF SITES. EXPECT SUB-VFR CIGS/VSBYS TO CORRESPOND TO ANY SHOWER/THUNDERSTORM ACTIVITY. LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 345 AM FRIDAY...PREDOMINANT VFR EXPECTED THROUGH THE EXTENDED PERIOD. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE SAT AS A SHORT WAVE MOVING ACROSS THE REGION IN NW FLOW ALOFT. THERE WILL BE SOME BRIEF REDUCED CIGS/VSBYS WHEN SHRA/TSRA CROSS OTHERWISE MOSTLY VFR EXPECTED. PRECIP COVERAGE EXPECTED TO DIMINISH SUN AND MON AS HIGH PRESSURE AND A LITTLE DRIER AIRMASS BUILDS IN FROM THE MID-ATLANTIC STATES...MAINTAINING VFR CONDITIONS THROUGH TUES. && .MARINE... SHORT TERM /THROUGH FRIDAY/... AS OF 330 AM FRIDAY...BENIGN BOATING WITH S SERIES OF SHORTWAVES MOVING THROUGH DURING THIS PERIOD. A SHORTWAVE WILL BE EXITING THE VA/NC COAST EARLY AND ANOTHER SHORTWAVE APPROACHING LATER BY THE AFTERNOON. THIS WILL LEAD TO CHC SHOWER/THUNDERSTORM ACTIVITY THROUGH THE DAY...ESPECIALLY LATER INTO THE AFTERNOON/EVENING HOURS. WINDS WILL BE VARIABLE TO START AND THEN PICK UP FROM THE WEST AROUND 10-12 KTS. A BACKDOOR COLD FRONT WILL MOVE SOUTH FRIDAY NIGHT BRINGING WIND AROUND FROM THE NORTHEAST. SEAS WILL GENERALLY BE AROUND 2 FEET FRIDAY AND BEGIN TO INCREASE 2 TO 3 FEET OVERNIGHT. LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 345 AM FRIDAY...COLD FRONT WILL SLOWLY PUSH S ACROSS THE WATERS INTO SAT. INITIALLY WINDS WILL BE LIGHT OVER THE COASTAL WATERS AS THE FRONT CROSSES...THEN NE WINDS WILL INCREASE TO 10-15 KTS SAT AFTERNOON WITH HIGHER GUSTS...ESPECIALLY ACROSS THE NORTHERN WATERS. SEAS AROUND 2-3 FT SAT AND MAY SEE SOME 4 FT SEAS FOR THE OUTER NORTHERN WATERS LATE SAT. NE WINDS WILL INCREASE TO 15-20 KTS SAT NIGHT AND SUN AS THE NE PRESSURE GRADIENT TIGHTENS WITH HIGH PRESSURE BUILDING S OVER INLAND AREAS. AS WINDS INCREASE SEAS WILL BUILD TO 3-5 FT...POSSIBLE REACHING 6 FT OUTER WATERS SUN NIGHT INTO MON. THE NE FLOW WILL GRADUALLY WEAKEN AS THE PRESSURE GRADIENT LOOSENS TUES BUT COULD POTENTIAL SEE ELEVATED SEAS CONTINUE FROM TROPICAL SYSTEM SWELL THROUGH MIDWEEK. LOCAL SWAN/NWPS AND 00Z WAVEWATCH IN GOOD AGREEMENT FOR THE MEDIUM RANGE...THUS USED BLEND OF THESE TWO WITH PREVIOUS FORECAST...THEN 00Z WAVEWATCH FOR THE EXTENDED SEAS. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...NONE. && $$ SYNOPSIS...JBM NEAR TERM...LEP SHORT TERM...LEP LONG TERM...DAG AVIATION...DAG/LEP MARINE...DAG/LEP

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