Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 010536 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 136 AM EDT MON SEP 1 2014 .SYNOPSIS... STRENGTHENING BERMUDA HIGH PRESSURE WILL MAINTAIN SUMMERTIME HEAT MUCH OF THIS FIRST WEEK OF SEPTEMBER. A WEAKENING FRONT WILL EDGE INTO THE REGION MID-WEEK...BRINGING AN ELEVATED CHANCE OF STORMS. A STRONG WAVE OF HEAT MAY EXPAND INTO THE CAROLINAS LATE THIS WEEK INTO NEXT WEEKEND...AS AN UPPER RIDGE OVER GULF STATES EXPANDS TO THE NORTH AND EAST. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 136 AM MONDAY...THE WEAKENING CONVECTION MOVED INTO PORTIONS OF DARLINGTON AND FLORENCE COUNTIES AND THEN DISSIPATED. ANOTHER SMALL AREA OF WARMING CLOUD TOPS WAS PRODUCING SHOWERS TO THE WEST OF FLORENCE AND WILLIAMSBURG COUNTIES LATE THIS EVE. THIS ACTIVITY IS NO LONGER PUSHING EASTWARD AND IS EXPECTED TO DISSIPATE UPSTREAM OF OUR FORECAST AREA. OUTFLOW BOUNDARIES FROM THIS CONVECTION SHOULD BECOME ACTIVE ON MONDAY. THE THICKER CLOUD CANOPY ACROSS MAINLY THE I-95 CORRIDOR IN SOUTH CAROLINA CONTINUES TO WARM AND THIN LATE THIS EVE. MAINLY THIN HIGHER CLOUDS ARE EXPECTED THROUGH MUCH OF THE NIGHT. AS WE PROGRESS THROUGH THE OVERNIGHT...SHOULD START TO SEE SOME STRATOCUMULUS IN ASSOCIATION WITH OFFSHORE CONVECTION AT LEAST SKIRT THE COAST. MORE INLAND AREAS MAY SEE SCT TO PERHAPS BKN STRATUS LATE. SHOWERS DEVELOPING ACROSS THE BAROCLINIC FAVORED WARM WATERS OF THE ATLANTIC MAY SKIRT THE COAST TOWARD MORNING. THE FLOW HAS BACKED A LITTLE TO THE SW AS THE BERMUDA RIDGE FURTHER STRENGTHENS ACROSS THE AREA. THIS WILL HAVE A TENDENCY TO KEEP THE SHOWERS OFFSHORE THROUGH SUNRISE...PERHAPS CLIPPING THE SOUTHPORT TO CAROLINA BEACH AREA AROUND DAYBREAK. A SLIGHTLY STRONGER NOCTURNAL JET SHOULD LARGELY PRECLUDE ANY SIGNIFICANT FOG DEVELOPMENT AND WILL NOT INCLUDE MENTION AT THIS TIME. THIS SAME JETTING SHOULD BE ENOUGH TO KEEP THE BOUNDARY LAYER FROM REMAINING FULLY DECOUPLED THROUGH THE NIGHT. THUS...WITH AT LEAST A SLIGHT SOUTHERLY BREEZE FROM TIME TO TIME...WOULD EXPECT MINIMUMS MAINLY IN THE LOWER TO MID 70S. AT THE BEACHES...WHERE THE BREEZE MAY PERSIST MUCH OF THE NIGHT...WILL FORECAST LOWS AROUND 80. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...THE NORTHERN 2/3RDS OF THE CONTERMINOUS U.S. WILL HAVE FAST WESTERLY FLOW...WHEREAS THE SOUTHERN 1/3RD WILL HAVE A FLATTENED RIDGE ALOFT. THIS FLOW WILL KEEP DYNAMICS ASSOCIATED WITH ANY S/W TROFS WITHIN THIS WESTERLY FLOW ALOFT...NORTH OF THE FA. AT THE SFC...RIDGING FROM THE WESTERN ATLANTIC HIGH WILL BE THE PRIMARY WEATHER FEATURE TO AFFECT THE FA. THE DIURNALLY DRIVEN SEA BREEZE AND THE PIEDMONT TROF...WILL PROVIDE THE PRIMARY SOURCES FOR LIFT EACH DAY FOR CONVECTION TO OCCUR. AT THIS POINT HAVE STAYED WITH CLIMO CHANCES FOR CONVECTION WHICH IS BASICALLY AROUND 30 PERCENT. ANY WEAK VORTS OR S/W TROFS ALOFT ABLE TO WORK THEIR WAY SOUTHWARD THAN WHAT MODELS INDICATE COULD RESULT WITH AN INCREASE IN POPS ABOVE CLIMO...30 PERCENT CHANCE. AVAILABLE MOISTURE WILL NO LONGER BE IN QUESTION AS MOISTURE IS PROGGED TO INCREASE THRU THE ATM COLUMN FROM MONDAY NIGHT THROUGH THE REMAINDER OF THE SHORT TERM VIA LATEST MODEL TIME HEIGHT DISPLAYS AND MODEL SOUNDING DATA. OF THE 2 DAYS...TUE WILL BE ILLUSTRATED WITH THE HIER POPS CHANCE AND CLOUD OVERALL COVERAGE. FOR TEMPS...PREVIOUS FORECAST WAS USED WITH ONLY MINOR TWEAKING NEEDED BASED ON 12Z MODEL MOS DATA. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 300 PM SUNDAY...HIGH PRESSURE WILL DOMINATE AT THE SURFACE WITH A WEAKENED GRADIENT FLOW. OVERALL A WARM AND HUMID AIRMASS WILL REMAIN IN PLACE WITH LOCALIZED SHOWER ACTIVITY EACH DAY MAINLY ASSOCIATED WITH SEA BREEZE BOUNDARY AND PIEDMONT TROUGH INLAND. PCP WATER VALUES REMAIN UP AROUND 2 INCHES BUT MOISTURE PROFILES SHOW MOST OF THE MOISTURE LOCKED IN ABOVE H5 WITH MORE IN THE WAY OF UPPER LEVEL CLOUDS. THE PREVAILING FLOW WILL REMAIN LIGHT WITH SEA BREEZE KICKING UP EACH AFTERNOON. FLAT MID TO UPPER RIDGE AMPLIFIES SLIGHTLY UP THROUGH THE SOUTHEAST WEDNESDAY THROUGH FRIDAY BEFORE A DEEPER SHORTWAVE RIDES ACROSS THE GREAT LAKES AND DIGS SOUTHWARD PUSHING A COLD FRONT INTO THE CAROLINAS BY THE LATTER HALF OF NEXT WEEKEND. THIS WILL PROVIDE LIMITED UPPER LEVEL SUPPORT FOR CONVECTION THROUGH THE WEEK INTO THE FIRST HALF OF THE WEEKEND. NOT EXPECTING ANY CHANGE IN AIR MASS THROUGH THE PERIOD WITH MAX TEMPS UP AROUND 90 OR SO AND OVERNIGHT LOWS HOLDING UP AROUND 70 OR SO. BUILDING H5 HEIGHTS THROUGH FRI SHOULD HELP KEEP TEMPS ABOVE NORMAL AND WILL BEGIN A SLIGHT DOWNWARD TREND AS TROUGH MAKES ITS WAY EAST INTO NEXT WEEKEND. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 06Z...VFR CONDITIONS TONIGHT MAY GIVE WAY TO PATCHY AREAS OF MVFR/IFR CIGS EARLY THIS MORNING. LAMP GUIDANCE AND FCST SOUNDINGS INDICATE KFLO/KLBT HAVE THE BEST CHANCES OF SEEING TEMPO IFR/LIFR CIGS DEVELOP JUST AFTER DAYBREAK. GIVEN EXTENSIVE DEBRIS CLOUDINESS AND NOCTURNAL LOW LEVEL JETTING...FOG SEEMS LESS LIKELY THAN LAST NIGHT...SO WILL JUST INCLUDE MVFR VSBYS FOR THE INLAND TERMS. ALONG THE COAST...HAVE INCLUDED TEMPO MVFR CIGS AS 1-2KFT CLOUDS MAY CLIP THESE SITES DURING THE EARLY MORNING HOURS. LIGHT SOUTHWEST FLOW SHOULD KEEP SHOWER ACTIVITY OFFSHORE...SO NO VCSH FOR THE COASTAL TERMS ATTM. VFR WILL PREVAIL DURING THE DAY AS SOUTHWEST WINDS AROUND 5 KT BECOME SOUTH AROUND 10 KT IN THE AFTN BEHIND THE SEA BREEZE. WE COULD SEE INCREASED SHOWER/TSTM ACTIVITY AFTER MIDDAY AS SOUNDINGS DO SHOW DEEPER MOISTURE AVAILABLE. BUT WILL HOLD OFF ON INCLUDING VCSH SINCE COVERAGE WOULD LIKELY BE ISO/SCT AT BEST. EXTENDED OUTLOOK...CHANCE OF SCATTERED AFTN SHOWERS/TSTMS THROUGH FRIDAY. PATCHES OF MVFR/IFR FOG OR STRATUS MAY ALSO DEVELOP EACH MORNING. BUT OVERALL VFR CONDITIONS SHOULD PREVAIL. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 136 AM MONDAY...A SLIGHTLY STRONGER NOCTURNAL JET AND A STRENGTHENING BERMUDA RIDGE WILL KEEP SOUTHWEST WINDS ACROSS THE WATERS TONIGHT. WIND SPEEDS WILL BE ON THE ORDER OF 10 TO 15 KT WITH GUSTS AROUND 20 KT. SEAS WILL BE 2 TO 3 FT WITH SOME 4 FT SEAS EXPECTED ACROSS THE OUTERMOST WATERS. DEVELOPING OFFSHORE CONVECTION MAY MOVE WITHIN 20 NM LATE...ESPECIALLY OFF THE CAPE FEAR COAST. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...THE PRESSURE PATTERN ACROSS THE AREA WATERS WILL BE THE RESULT OF THE INTERACTION BETWEEN RIDGING FROM THE WESTERN ATLANTIC HIGH AND PIEDMONT TROUGH. LOOKING AT SYNOPTIC WINDS IN THE SSW THRU WSW WIND DIRECTION...WITH AN OVERALL SLIGHT BACKING EACH AFTN AND EVENING FROM THE DIURNALLY DRIVEN SEA BREEZE. THE SFC PG WILL BECOME MODEST AT BEST RESULTING WITH 10-15 KT OR A SOLID 15 KT WIND SPEED. SIGNIFICANT SEAS WILL RUN 2 TO OCCASIONALLY 3 FT...WITH MAJORITY OF THE SIG. SEAS A RESULT OF THE 2 FOOT SE GROUND SWELL RUNNING ROUGHLY AT 9-10 SECOND PERIODS. WIND DRIVEN WAVES ESPECIALLY FROM THE SEA BREEZE WILL RUN SIG. SEAS UP TO 3 TO POSSIBLY 4 FT. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 300 PM SUNDAY...HIGH PRESSURE WILL CONTINUE TO DOMINATE WITH A RELAXED GRADIENT FLOW. OVERALL EXPECT WEAK SOUTHERLY FLOW 10 KTS OR LESS DOMINATED BY SEA/LAND BREEZE. WINDS WILL SPIKE UP EACH AFTERNOON NEAR SHORE AS SEA BREEZE STRENGTHENS. SEAS WILL REMAIN FAIRLY BENIGN WITH HEIGHTS LESS THAN 3 FT AND SLIGHT CHOP IN THE AFTN SEA BREEZE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...8 NEAR TERM...RJD/8 SHORT TERM...DCH LONG TERM...RGZ AVIATION...BJR/8

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