Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 230804 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 404 AM EDT SAT MAY 23 2015 .SYNOPSIS... CENTER OF HIGH PRESSURE TO MOVE OFF THE MID-ATLANTIC COAST TODAY...AND WELL OFFSHORE DURING THE UPCOMING WEEK. ITS SFC RIDGE AXIS WILL EXTEND WESTWARD ACROSS THE ATLANTIC WATERS AND INTO NC. THIS AXIS WILL REMAIN NORTH OF THE LOCAL AREA RESULTING IN AN ONSHORE FLOW THIS WEEKEND AND LIKELY CONTINUING THRUOUT MUCH OF THE UPCOMING WEEK. THIS WILL KEEP TEMPS AT OR SLIGHTLY BELOW NORMAL. THE MID TO LATE WEEK PERIOD WILL SEE A RETURN TO HIGHER HUMIDITY LEVELS ALONG WITH A SMALL RISK FOR SHOWERS AND THUNDERSTORMS BEGINNING THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM SATURDAY...COOL HIGH PRESSURE WAS CENTERED ACROSS PENNSYLVANIA EARLY THIS MORNING AND WAS RIDGING STRONGLY SOUTHWARD ACROSS THE CAROLINAS. A FRONT...THE LEADING EDGE OF EVEN DRIER AIR...WAS DROPPING SOUTH ACROSS VIRGINIA. THIS FRONT WILL LOSE ITS SOUTHWARD PUSH AND BECOME ILL-DEFINED AS THE CENTER OF HIGH PRESSURE SLOWLY SHIFTS OFFSHORE OF THE MID-ATLANTIC STATES THROUGH TONIGHT. THE HIGH WILL RIDGE BACK ACROSS THE EASTERN CAROLINAS TONIGHT. THE LOW-LEVEL FLOW WILL SHIFT FROM NE THIS MORNING TO E AND ESE THIS AFTERNOON AND TONIGHT. THE ONSHORE FLOW WILL GRADUALLY INCREASE THE SUPPLY OF LOW-LEVEL MOISTURE. MINIMUM AFTERNOON RELATIVE HUMIDITY LEVELS WILL STILL BE LOW INLAND...AROUND 30 PERCENT. EXCEPT FOR SOME THIN CIRRUS WISPS...IT WILL BE SUNNY TODAY. EVEN FLAT CUMULUS ATOP THE MIXED LAYER WILL BE HARD TO COME BY DURING PEAK HEATING. TONIGHT...THE WINDS ABOVE THE BOUNDARY LAYER WILL INCREASE AND THIS SHOULD BE ENOUGH TO LIMIT ANY WIDESPREAD FOG CONCERNS. HOWEVER...WOULD EXPECT SOME PATCHY LATE NIGHT FOG TO DEVELOP. AS MOISTURE INCREASES IN THE 4-6 KFT LAYER...WE MAY BEGIN TO SEE SOME STRATOCUMULUS DEVELOP OR ADVECT INTO THE AREA FROM OFFSHORE. WE WILL BEGIN THE DAY UNSEASONABLY COOL WITH TEMPS IN THE LOWER TO MID 50S...BUT NOT QUITE AS COOL AT THE BEACHES. BRIGHT SUNSHINE WILL REBOUND AFTERNOON HIGHS INTO THE COMFORTABLE LOWER 80S. AN ONSHORE FLOW WILL KEEP HIGHS AT THE BEACHES AND NEARBY ENVIRONS IN THE UPPER 70S. NOT AS COOL TONIGHT WITH LOWS IN THE UPPER 50S TO NEAR 60 DEGREES INLAND AND LOWER TO MID 60S ALONG THE MORE COASTAL LOCATIONS. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED AS NEARLY PICTURE PERFECT WX FOR THIS MEMORIAL HOLIDAY WEEKEND. NOT TOO HOT NOR COLD. NO PRECIPITATION...AND...MOSTLY SUNNY SKIES EACH DAY AND MOSTLY CLEAR SKIES EACH NIGHT. MID AND UPPER LEVEL RIDGING OVERHEAD TO AFFECT THE FORECAST AREA. IN FACT...THE MID-UPPER LEVEL HIGH WILL BE ANCHORED JUST OFF THE SOUTHEAST U.S. COAST...WITH ITS SOUTH TO NORTH RIDGE AXIS JUST WEST OF THE ILM CWA SUNDAY...WILL DRIFT TO A POSITION THATS NEARLY OVERHEAD BY MONDAY NIGHT. SFC HIGH PRESSURE CENTERED JUST OFF THE DELMARVA COAST ON SUNDAY...WILL DRIFT EASTWARD AND FURTHER OFFSHORE BY MONDAY NIGHT. ITS SFC RIDGE AXIS WILL EXTEND WSW INTO NC AND FOR THE MOST PART ITS AXIS TO REMAIN NORTH OF THE ILM CWA. THIS POSITION WILL RESULT WITH AN ONSHORE FLOW PATTERN THAT WILL EXTEND UPWARDS TO NEAR 850MB. THIS PATTERN WILL RESULT IN THE DAILY MAX AND MIN TEMPS RUNNING AT OR JUST BELOW CLIMO. THE MOISTURE IN THE LOWER LEVELS WILL INCREASE DUE TO THE ONSHORE FLOW...AND LIKELY BE USED TO PRODUCE DIURNALLY DRIVEN SCATTERED CU EACH DAY...ESPECIALLY ALONG THE DAILY RESULTANT WIND BOUNDARY AKA THE SEA BREEZE. IN ADDITION TO THE CU...CONVECTIVE DEBRIS CLOUDS IN THE FORM OF THIN TO OCCASIONALLY OPAQUE CIRRUS WILL OCCASIONALLY SPILL OVER THE UPPER RIDGE AXIS AND ACROSS THE ILM CWA. AS FOR TEMPS...STAYED WITH THE MODEL MOS GUIDANCE EXHIBITING THE LOWER MAX/MINS. WITH AN ONSHORE FLOW ACROSS A DECENT FETCH FOR BOTH DAYS...EXPECT AN E TO SE GROUND SWELL TO INCREASE IN SIZE...AND ALSO BECOME PERPENDICULAR TO THE AREA BEACHES. THIS WILL LIKELY INCREASE THE RIP CURRENT THREAT FOR AREA BEACHES THRUOUT THE ILM CWA. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 330 AM SATURDAY...THE MID TO UPPER LEVEL RIDGE AXIS TO BE NEARLY OVERHEAD ON TUESDAY...THEN SLIGHTLY DRIFT JUST OFF THE SOUTHEAST U.S. COAST TOWARD THE END OF THE WEEK. THIS A RESULT OF UPSTREAM FORCING TRYING TO PUSH/PROGRESS THIS FEATURE EASTWARD. HOWEVER...A FLY IN THE OINTMENT IN THE FORM OF A MID-UPPER LOW OVER THE MID-ATLANTIC OCEAN APPROACHING THE US MAINLAND FROM THE SOUTHEAST. IT LOOKS OMINOUS ALOFT...HOWEVER AT THE SFC...THERE IS NO ACCOMPANYING STRONG SFC LOW...JUST A TROF OF LOW PRESSURE. THIS UPPER LOW WILL SLOW THE PROGRESSION OF THE UPPER RIDGE EASTWARD...AND THUS ALLOW THE CONTINUANCE OF DECENT WX CONTINUING THRU THE END OF THE WORK WEEK OF NEXT WEEK. ENOUGH SUBSIDENCE ALOFT WILL PREVENT WIDESPREAD PCPN...HOWEVER THE FORCING FROM THE DAILY SEA BREEZE WILL LIKELY BE ENOUGH TO CARRY A LOW CHANCE FOR CONVECTION. MOISTURE IN THE FORM OF CLOUDS COULD REACH THE COASTAL CAROLINAS AS THE MID-ATLANTIC UPPER LOW REACHES ITS CLOSEST APPROACH ON FRI. FOR NOW HAVE KEPT ANY PCPN ASSOCIATED WITH IT WELL OFFSHORE FROM THE MAINLAND. HAVE ALSO PREVENTED THE PCPN WEST OF THE ILM CWA FROM MOVING EASTWARD INTO THE ILM CWA...AS THE FA REMAINS SANDWICHED BETWEEN THE ATLANTIC LOW AND THE MID-UPPER TROF ALONG THE SPINE OF THE APPALACHIANS. MAX/MIN TEMPS THRU THIS PERIOD WILL BE JUST ON EITHER SIDE OF CLIMO. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... AS OF 06Z...VFR WITH CLEAR SKIES EXPECTED THROUGH SUNRISE. WINDS WILL BE LIGHT AND VARIABLE. 1-3 DEGREE TEMP/DEW POINT SPREADS WITH DRIER AIR JUST OFF THE SURFACE IN THE PRE-DAWN HOURS SUGGEST LITTLE IF ANY POTENTIAL BR ISSUES. HOWEVER...CAN NOT DISCOUNT THE POSSIBILITY OF A BRIEF BOUT OF MVFR/IFR VSBYS ESPECIALLY AT KLBT AND KCRE THROUGH SUNRISE. CONFIDENCE IS LOW HOWEVER. VFR AFTER SUNRISE WITH NE WINDS BECOMING E-SE IN THE AFTERNOON. EXTENDED OUTLOOK...VFR. MORNING FOG POSSIBLE MONDAY AND WEDNESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM SATURDAY...A VERY MODEST MINI SURGE WILL BE UNDERWAY THIS MORNING AS COOL AND DRY HIGH PRESSURE TO THE NORTH MAKES ITS FINAL PUSH SOUTHWARD. THE HIGH WILL GRADUALLY SHIFT OFFSHORE OF THE MID-ATLANTIC STATES THROUGH TONIGHT AS IT RIDGES BACK ACROSS THE CAROLINA WATERS. NE WINDS EARLY THIS MORNING WILL SHIFT TO E AND ESE FOR THE REMAINDER OF THE DAY AND TONIGHT. WIND SPEEDS WILL GENERALLY BE 10 TO 15 KT. SEAS WILL BE 2 TO 3 FT TODAY AND 3 TO 4 FT TONIGHT AS AN INCREASING EASTERLY FETCH AROUND OFFSHORE HIGH PRESSURE BRINGS A WEAK ESE SWELL INTO THE WATERS ON THE ORDER OF 9 TO 10 SECONDS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 AM SATURDAY...THE SFC RIDGE AXIS FROM THE HIGH OFFSHORE FROM THE DELMARVA COAST...IS PROGGED TO EXTEND WSW INTO NC BUT REMAIN FOR THE MOST PART NORTH OF THE ILM WATERS. THIS WILL RESULT IN AN ONSHORE E-SE FLOW THRU THIS PERIOD. EXPECT A SEMI-TIGHTENED SFC PG SOUTH OF THE SFC RIDGE AXIS...THUS RESULTING IN SPEEDS AROUND 15 KT. WITH A DECENT FETCH...EXPECT SIGNIFICANT SEAS TO BUILD TO 3 TO 4 FT...POSSIBLY A FEW 5 FOOTERS LATE MON NIGHT. IN ADDITION...LOOK FOR INCREASING PERIODS THAT COULD RESULT IN WIND DRIVEN WAVES TRANSITIONING INTO A PSEUDO GROUND SWELL. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 330 AM SATURDAY...WEAKENING UPPER RIDGING TO HOLD ON THRU WEDNESDAY AS IT BECOMES SANDWICHED ACROSS THE AREA WATERS. THIS DUE TO THE APPROACHING MID-UPPER MID-ATLANTIC LOW FROM THE SE...AND AN UPPER TROF TRYING TO PROGRESS EASTWARD ACROSS EASTERN U.S. AND GETS HUNG UP ALONG THE WINDWARD SIDE OF THE APPALACHIANS. THE SFC PRESSURE PATTERN ACROSS THE LOCAL WATERS WILL RESULT IN SE WINDS AT 10 TO 15 KT....LIKELY A SOLID 15 KT ACROSS THE SOUTHERNMOST WATERS DUE TO AN INCREASED SFC PG. NO REAL SFC ENTITY ACCOMPANYING THE MID-ATLANTIC UPPER LOW...JUST A SFC TROF EXHIBITED BY THE MODELS. BUT WITH A DECENT E-SE FETCH CONTINUING TO OCCUR...LOOK FOR A SOLID 3 TO 4 FT SEAS WITH 5 FOOTERS NOT OUT OF THE QUESTION AS WAVEWATCH3 ILLUSTRATES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...DCH NEAR TERM...RJD SHORT TERM...DCH LONG TERM...DCH AVIATION...RJD/MRR

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