AFDCHS AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 408 AM EDT FRI JUL 8 2011 .SYNOPSIS... DEEPER MOISTURE WILL GRADUALLY INCREASE OVER THE REGION THROUGH TONIGHT AS WEAK LOW PRES ALONG THE GULF COAST PERSISTS. A WEAK COLD FRONT WILL MOVE INTO THE AREA OVER THE WEEKEND...THEN MOVE THROUGH AND DISSIPATE BY MON. ANOTHER FRONT WILL APPROACH FROM THE N BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... PRE-DAWN...SHOWERS WERE ON THE INCREASE IN THE CHARLESTON TRI-COUNTY AREA AS A WEAK MID LEVEL DISTURBANCE WAS LIFTING SLOWLY N THROUGH NE FLORIDA. MOISTURE CONVERGENCE HAS BECOME DEEPER ALONG THE SOUTH CAROLINA COAST OVER THE PAST FEW HOURS AND WITH PWATS AROUND 2 INCHES WE THINK COVERAGE WILL CONTINUE TO INCREASE THROUGH MID MORNING. WE HAVE MAINTAINED CHANCE POPS THERE WITH MOST OTHER AREAS TO THE W OF I-95 STAYING DRY. TODAY...AFTER THE SCATTERED MORNING CONVECTIVE RAINS SLIDE FURTHER UP THE COAST TOWARD THE PEE DEE AND SE NORTH CAROLINA...ATTENTION IS EXPECTED TO TURN TO DIURNAL DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS AND TSTMS OVER MUCH OF THE SOUTHERN HALF OF GEORGIA AS THE WEAK VORT OVER N FLORIDA INTERACTS WITH DEEP MOISTURE AND VARIOUS MESOSCALE BOUNDARIES. WE SHOW AFTERNOON POPS BECOMING LIKELY ALONG AND S OF I-16 IN GEORGIA. SLOW MOVEMENTS AND CELL MERGERS SUGGEST A LOCALLY HEAVY RAINFALL POTENTIAL. IN SOUTH CAROLINA THIS AFTERNOON...IT LOOKS TRICKY AS THE REGION WILL HAVE HIGH PWATS BUT POSSIBLY SOME RESIDUAL SUBSIDENCE IN THE WAKE OF THE FIRST OFFSHORE LEAD WAVE AND AN APPROACHING UPSTREAM SHORT WAVE HEADED FOR THE MID ATLC REGION. CONVECTION UPSTREAM IN THE MIDLANDS AND UPSTATE LOOKS TO HAVE A POTENTIAL TO ORGANIZE LATE DAY AND POSSIBLY BECOME SEVERE. THIS PLACES OUR SOUTH CAROLINA INLAND AREAS BETWEEN THE SYSTEMS. WE MAINTAINED SOME LOWER END CHANCE POPS LATE DAY BUT WOULD NOT BE SURPRISED IF CONVECTION ENDS UP RATHER SPARSE IN SPOTS. CLOUDS ARE A BIT TRICKY TODAY BUT WE MAINTAINED SOME LOWER TO MID 90S AGAIN...WARMEST WELL INLAND. SW WINDS WILL PICK UP LATER IN THE AFTERNOON. TONIGHT...CONVECTION IN SE GEORGIA SHOULD WANE AFTER A DIURNAL LATE DAY/EARLY EVENING MAX BUT STILL ENOUGH EVIDENCE TO KEEP SOME LOW POPS GOING MUCH OF THE OVERNIGHT. IN SOUTH CAROLINA...BOUNDARIES FROM UPSTREAM TSTMS MAY INTERACT WITH OTHER BOUNDARIES AND FIRE SOME SHOWERS AND STORMS AT ANY POINT OVERNIGHT. COASTAL RAIN CHANCES ALSO MAY INCREASE AFTER MIDNIGHT AS THE MID LEVEL VORT MAX EASES OFF THE SE GEORGIA COAST AND DEEP MOIST CONVERGENCE BECOMES ENHANCED. && .SHORT TERM /SATURDAY THROUGH MONDAY/... I HAVE DISCOUNTED THE 00Z NAM THIS MORNING AS SURFACE LOW SEEMS WAY OVERDONE. I PREFER THE GLOBAL MODEL SOLUTIONS OF A SLOW MOVING FRONT INTO THE AREA LATER IN THE WEEKEND...THEN GRADUALLY DISSIPATING EARLY NEXT WEEK. SATURDAY...THE ATMOSPHERE SHOULD BE STOKED WITH DEEP MOISTURE. PWATS WILL BE 2 TO 3 SDS ABOVE NORMAL WITH ABSOLUTE VALUES IN EXCESS OF 2 INCHES. THERE WILL BE MORE CLOUDS AROUND ON SATURDAY AS SOUTHERN END OF MID LATITUDE TROF MEETS UP WITH REMNANTS OF THE UPPER LOW OVER THE GULF OF MEXICO TO GIVE A SLIGHTLY ENHANCED SOUTHWESTERLY JET OVERHEAD...TRANSPORTING A FAIR AMOUNT OF CIRRUS INTO THE AREA. THIS WILL KEEP TEMPS A DEGREE OR TWO BELOW AVERAGE...BUT HIGH DEW POINTS WILL KEEP THE APPARENT TEMPERATURE ELEVATED. I WENT WITH JUST SLIGHTLY ABOVE NORMAL POPS...WITH ACTIVITY EXTENDING INTO THE EVENING HOURS AWAY FROM THE COAST AS PRE-FRONTAL TROF DROPS INTO THE AREA FROM THE NORTHWEST. SUNDAY WE WILL SEE SOME SUBTLE DIFFERENCES AS WEAKENING FRONT MOVES INTO THE NORTHERN FA. THERE WILL STILL BE PLENTY OF DEEP MOISTURE...BUT UPPER LEVEL WINDS WILL SLACKEN BACK OFF AS HEIGHTS BEGIN TO REBUILD...MEANING LESS CLOUD COVER. TEMPS WILL BE BACK TO A TOUCH ABOVE NORMAL BY SUNDAY AFTERNOON...BUT DYING FRONT IN THE AREA WILL SUPPORT ANOTHER ROUND OF AFTERNOON AND EVENING CONVECTION. BEST CHANCES FOR THUNDERSTORMS WILL BE ALONG THE SEA BREEZE AS WELL AS THE WEAKENING BOUNDARY. ON MONDAY...THE FRONT WILL ESSENTIALLY HAVE DISSIPATED...ALTHOUGH A VERY WEAK SURFACE TROF AND MID LEVEL SHEAR ZONE IS EXPECTED TO HANG AROUND. PWS WILL DROP BACK BELOW 2 INCHES WITH A LITTLE MID LEVEL DRYING FROM THE RIDGE BUILDING NORTH OF THE AREA...BUT CONVECTIVE TEMPS WILL BE EASILY REACHED IN THE AFTERNOON DUE TO PLENTIFUL SUNSHINE...SO AT LEAST A SLIGHT CHANCE OF THUNDERSTORMS IS EXPECTED. ALSO...WITH HIGHER TEMPS IN THE AFTERNOON AND DEW POINTS REMAINING REASONABLY HIGH...HEAT INDICES MAY START TO APPROACH ADVISORY LEVELS. THIS WILL HAVE TO BE WATCHED. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... TUESDAY LOOKS QUITE SIMILAR TO MONDAY AS WIDELY SCATTERED AFTERNOON AND EVENING CONVECTION IS EXPECTED...BUT LOTS OF SUNSHINE WILL ALLOW TEMPS TO RISE WELL INTO THE 90S AWAY FROM THE COAST WITH HEAT INDICES INTO THE MID 100S. THE SECOND HALF OF THE WEEK IS MORE COMPLICATED. GFS HAS SHIFTED SIGNIFICANTLY FROM ITS SOLUTION 24 HOURS. NOW..INSTEAD OF HOLDING UP THE NEXT COLD FRONT NORTH OF THE AREA...IT PLOWS IT THROUGH MID WEEK AND BRINGS IN A SIGNIFICANTLY DRIER AIR MASS FOR THURSDAY AND FRIDAY. I HAVE ONLY NUDGED THE FORECAST SLIGHTLY IN THAT DIRECTION DUE TO THE LACK OF CONTINUITY...PLUS THE FACT THAT YESTERDAYS ECMWF HAS BACKED OF ITS FRONTAL PASSAGE BY A DAY. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... THERE ARE SOME PATCHY MVFR CIGS ALONG THE EXTREME SOUTHERN COAST OF SOUTH CAROLINA JUST PRIOR TO 06Z AND WE SUSPECT AREAS OF MVFR CIGS MAY IMPACT KCHS LATER TONIGHT INTO MID MORNING AS DEEPER MOISTURE BUILDS AND PATCHY IFR CIGS CANNOT BE RULED OUT. A BIT LESSER CHANCE AT KSAV BUT WITH DEBRIS CLOUDS THINNING AND ALREADY THE OBSERVATION REPORTING FEW 600 FT STRATUS...MVFR/IFR MAY BE POSSIBLE OVERNIGHT...AT LEAST IN A PATCHY MODE. TODAY INTO THIS EVENING...WE THINK VFR CONDITIONS WILL PREVAIL WITH THE BEST CHANCES OF SHOWERS AND TSTMS AT KCHS DURING THE MORNING HOURS...AND POSSIBLY AROUND KSAV THIS AFTERNOON. OUR CONFIDENCE IS NOT HIGH ENOUGH TO GO WITH ANYTHING BUT CB MENTIONS AT THIS TIME. SURFACE WINDS WILL BE A BIT STRONGER THIS AFTERNOON AND EVENING THAN PREVIOUS DAYS...ESPECIALLY AT KCHS WHERE PERHAPS A FEW GUSTS NEAR 20 KT AT TIMES LATE DAY. EXTENDED AVIATION...AS IS USUALLY THE CASE IN MID SUMMER...THE BEST CHANCE FOR MVFR/IFR CIGS/VSBYS IS WITH THE CHANCES OF AFTERNOON AND EVENING CONVECTION NEAR THE TERMINALS. ALSO...WITH WINDS EXPECTED TO GET VERY LIGHT ON MONDAY AND TUESDAY MORNINGS...THERE COULD BE A COUPLE OF HOURS OF BR AROUND SUNRISE EACH DAY. && .MARINE... THE LOW LEVEL PRES GRADIENT IS EXPECTED TO PINCH BETWEEN ATLC HIGH PRES AND WAVES OF LOW PRES ACROSS THE NE GULF OF MEXICO AND THE MID ATLC REGION TODAY INTO TONIGHT. SEAS WERE ALREADY ELEVATED WITH NEAR 3 FT CLOSE TO SHORE AND 4-6 FT WELL OFFSHORE...HIGHEST NEAR THE EDISTO BUOY E OF CHARLESTON. SSW FLOW SHOULD EBB SOMEWHAT LATER THIS MORNING AND THEN BECOME SW AND INCREASE TO 15 TO 20 KT LATE TODAY. THE BEST WAVE ACTION WILL LIKELY END UP ALONG THE SOUTH CAROLINA COAST THROUGH TONIGHT AND WE WILL NEED TO WATCH FOR A PERIOD OF SCA CONDITIONS OVERNIGHT AS THE LOW LEVEL JET PEAKS. OVER OUR OUTER GEORGIA WATERS FROM 40-60 NM...WE HAVE ISSUED AN ADVISORY FOR TONIGHT AS SEAS WILL BE NEAR 6 FT AND SW WINDS FREQUENTLY GUST TO 25 KT. RIP CURRENTS...SE SWELLS WILL INCREASE TODAY AND THIS WILL CONTRIBUTE TO AN ENHANCED RISK FOR RIP CURRENTS FOR ALL OF OUR BEACHES. WINDS WILL STAY UP ON SATURDAY IN THE 15 TO 20 KNOT RANGE...MAYBE A BIT STRONGER IN THE EARLY MORNING HOURS IN THE CHARLESTON COUNTY WATERS...BUT WILL START TO DIMINISH AS THE FRONT WEAKENS SATURDAY NIGHT AND SUNDAY. GRADIENT WILL BE PRETTY SLACK ON MONDAY AND TUESDAY WITH LIGHT WINDS GENERALLY OUT OF THE SOUTH AND SOUTHWEST...TURNING ONSHORE NEAR THE COAST IN THE AFTERNOON AND EVENING. WINDS MAY PICK UP SOME AGAIN ON WEDNESDAY AHEAD OF THE NEXT FRONT. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 6 AM EDT SATURDAY FOR AMZ374. && $$