Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 221038 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 639 AM EDT FRI MAY 22 2015 .SYNOPSIS... HIGH PRESSURE AND MUCH DRIER AIR WILL BUILD INTO REGION AND CONTINUE INTO THE WEEKEND. HIGH PRESSURE WILL SHIFT OFFSHORE EARLY NEXT WEEK WITH HIGHER HUMIDITY LEVELS RETURNING TO THE AREA. && .NEAR TERM /THROUGH TONIGHT/... AS OF 600 AM FRIDAY...A COLD FRONT HAS MOVED WELL OFFSHORE AND HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS THE FORECAST AREA FROM THE NW AND N. AN INVERSION HAS TRAPPED MOISTURE AROUND 5 KFT EARLY THIS MORNING...KEEPING A GOOD DEAL OF MID CLOUDS ACROSS THE FORECAST AREA. THIS INVERSION SHOULD ERODE MID TO LATE MORNING... ALLOWING THESE CLOUDS TO DISSIPATE. AT THE SAME TIME...JET CIRRUS IS EXPECTED TO BE THINNING. WE MAY SEE SOME FLAT CUMULUS ATOP THE MIXED LAYER MIDDAY AND THIS AFTERNOON...BUT OTHERWISE IT WILL BE A MOSTLY SUNNY AFTERNOON. DEWPOINTS ARE EXPECTED TO DROP INTO THE 40S TODAY...THAT IS A 25 TO 30 DEGREE TURN AROUND FROM THU...SO FOR MOST...IT WILL FEEL MUCH MORE COMFORTABLE. RELATIVE HUMIDITY VALUES WILL BE AS LOW AS AROUND 30 PERCENT THIS AFTERNOON. TEMPS AT 850 MB WILL BE COOLING TO AROUND 10 DEG C AND THIS SHOULD KEEP HIGHS TODAY IN THE MID AND UPPER 70S. EXCEPT FOR SOME CIRRUS...SKIES WILL BE CLEAR TONIGHT. HIGH PRESSURE WILL BE CENTERED ACROSS PENNSYLVANIA AND THE NORTHERN MID-ATLANTIC OVERNIGHT. WE DO EXPECT WINDS WILL BE LIGHT AND WITH THE DRY AIR IN PLACE...LOWS SHOULD DROP INTO THE 50S AND AS COOL AS THE LOWER 50S. THE BEACHES WILL BE WARMEST...AROUND 60 DEG. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 200 AM FRIDAY...MID-LEVEL NORTH TO SOUTH TROF LINE INITIALLY OVER THE FORECAST AREA...WILL SLIDE OFF THE EAST COAST DURING SATURDAY. AT THE SAME TIME...MODELS INDICATE SOME AMPLIFICATION WITH THE UPPER TROF/LOW COVERING AN AREA FROM THE WEST COAST OF THE U.S. TO THE ROCKIES. GIVEN THE YING/YANG PRINCIPLE...THIS AMPLIFICATION WITH THE UPPER TROF WILL RESULT IN THE AMPLIFICATION OF THE UPPER RIDGE ACROSS THE EASTERN U.S...WITH THE UPPER RIDGE AXIS EXTENDING FROM THE SOUTHEAST U.S. TO THE SOUTHERN GREAT LAKES. THE UPPER HIGH ITSELF WILL REMAIN CENTERED OVER THE SE STATES. AT THE SFC...MODELS ILLUSTRATE THE CENTER OF THE 1030+ MB SFC HIGH WILL DROP SE-WARD FROM THE GREAT LAKES TO THE MID-ATLANTIC COAST DURING SATURDAY...AND BECOME CENTERED OFFSHORE FROM THE ILM NC COAST DURING SUNDAY. THE SFC RIDGE AXIS FROM THE HIGHS CENTER WILL CONTINUE TO EXTEND WESTWARD BACK ACROSS THE ILM CWA THROUGH SUNDAY NIGHT. THIS PATTERN WILL KEEP POPS AT BAY...AND FOR THE MOST PART CLOUDINESS TOO. BY LATE SUNDAY INTO SUNDAY NIGHT...THE NORTH TO SOUTH UPPER RIDGE AXIS WILL BE AT ITS CLOSEST APPROACH TO THE ILM CWA....BUT STILL REMAINING WEST OF THE FA. COULD SEE DEBRIS CLOUDINESS IN THE FORM OF CI/CS AND POSSIBLY ALTOCU TRACK ACROSS THE UPPER RIDGE AXIS AND ACROSS THE FA WHILE AT THE SAME TIME SCOURING OUT AS THE CLOUDS TRACK WITHIN A DOWNSLOPE TRAJECTORY OFF THE APPALACHIANS. THE MAIN AND DEEPER CLOUD SHIELD WILL REMAIN WEST AND NORTH OF THE ILM CWA DURING THIS PERIOD. AS FOR TEMPS AND HUMIDITY...THE FA WILL BE LOOKING AT A WEEKEND WITH TEMPS RUNNING 5 TO AS MUCH AS 10 DEGREES BELOW NORMAL...ESPECIALLY WITH NIGHTTIME LOWS. IN ADDITION...THE AIRMASS WILL BE ON THE DRY SIDE THIS WEEKEND...WITH PROGGED SOUNDINGS INDICATING PWS AROUND 1/2 INCH SATURDAY...AND BETWEEN 0.5 TO LESS THAN 1 INCH ON SUNDAY. THE EAST-SOUTHEAST LOW LEVEL FLOW ON SUNDAY...MAY BRING ENOUGH LOW LEVEL MOISTURE ACROSS THE FA TO PRODUCE DIURNALLY DRIVEN CU DURING SUNDAY. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 200 AM FRIDAY...THE STRENGTH OF THE UPPER RIDGING EXTENDING FROM THE UPPER HIGH OVER THE SE STATES...WILL PEAK MONDAY INTO TUESDAY. THERE-AFTER...MODELS ONLY DRIFT THE NORTH TO SOUTH UPPER RIDGE AXIS ACROSS AND JUST EAST OF THE FA BY LATE TUE THRU THU. MODELS ARE DISSIMILAR WITH THE STRENGTH OF THE UPPER LOW WELL OFFSHORE AND/OR ACROSS THE HIGH SEAS OF THE ATLANTIC OCEAN...AND ITS MOVEMENT WESTWARD TOWARD THE U.S. MAINLAND. THIS COULD TEMPORARILY PREVENT THE UPPER RIDGE AXIS FROM PROGRESSING OFF THE EAST COAST. BUT FOR NOW...WILL CONTINUE WITH THE THEME OF THE UPPER RIDGE AXIS OFF THE EAST COAST AND THUS ALLOWING SW FLOW ALOFT TO OVERTAKE THE FA WITH INCREASING MOISTURE AND WARMING TEMPS IN THE LOW LEVELS AS THE STRENGTH OF THE SFC HIGH ACROSS THE FA DECREASES BUT NEVERTHELESS CONTINUES TO RIDGE BACK WESTWARD ACROSS PORTIONS OF THE FA. OVERALL...WILL BE LOOKING AT WARMER TEMPS AND INCREASING MOISTURE EACH DAY WITH THE THREAT OF PCPN FROM MAINLY DIURNALLY DRIVEN CONVECTION...WITH THE DAILY BUT SHALLOW SEA BREEZE SUPPLYING ENOUGH SFC CONVERGENCE AND DYNAMICS TO GET THINGS STARTED. FOR NOW WILL INDICATE POPS IN THE LOW CHANCE...WITH GFS MOS GUIDANCE ALSO CONCURRING. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AS OF 12Z...LOW PRESSURE HAS MOVED FAIRLY RAPIDLY TO THE NORTHEAST AND OUT OF THE REGION...REPLACED WITH WEAK HIGH PRESSURE. THE COLD FRONT IS SOUTH OF THE REGION WITH NORTHERLY WINDS AROUND THE HIGH EXPECTED. TIME HEIGHT SHOWS SOME MID LEVEL MOISTURE LINGERING THROUGH THE MORNING HOURS...WITH SCATTERED SKIES EXPECTED THIS AFTERNOON THROUGH THE END OF THE FORECAST PERIOD. MOISTURE PROFILES ARE TOO DRY TO SUPPORT FOG OVERNIGHT. EXTENDED OUTLOOK...VFR. MORNING FOG POSSIBLE MONDAY AND TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 600 AM FRIDAY...A SMALL CRAFT SHOULD EXERCISE CAUTION HEADLINE REMAINS VALID THIS MORNING...EXCEPT FOR THE SEGMENT FROM LITTLE RIVER INLET TO MURRELLS INLET. A NORTHERLY SURGE IS UNDERWAY IN THE WAKE OF A COLD FRONT WITH WINDS FROM THE NNE AROUND 20 KT AND SEAS OF 4 TO 5 FT. A FEW GUSTS TO 25 KT ARE EXPECTED THIS MORNING. SEAS WILL BE LOWER WHERE A NNE FETCH IS SEVERELY LIMITED. THE SURGE WILL BE BRIEF AND LATE THIS MORNING AND THIS AFTERNOON... WINDS AND SEAS WILL BE ON A STEADY DECLINE. DURING THE AFTERNOON AND EVE...NE WINDS WILL DIMINISH TO 10 KT OR LESS. A SLIGHT REINFORCEMENT OF THE MUCH DRIER AND COOLER AIR TONIGHT SHOULD ALLOW NE WINDS TO INCREASE TO 10 TO 15 KT LATE. SEAS WILL RESPOND...SUBSIDING TO AROUND 2 FT DURING THE AFTERNOON AND EVE AND THEN BUILDING ABOUT A FOOT LATE TONIGHT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 200 AM FRIDAY...COULD SEE A BRIEF CAA SURGE EARLY SATURDAY...RESULTING WITH HIER WINDS AT 10 TO POSSIBLY 20+ KT. COULD SEE BRIEF SCEC OR EVEN SCA CONDITIONS. THIS WILL BE FOLLOWED BY THE SFC HIGHS 1030+ MB CENTER PROGGED TO MOVE OFF THE MID- ATLANTIC COAST BY LATE SATURDAY...TO WELL OFFSHORE DURING SUNDAY. WHILE AT THE SAME TIME...CONTINUING TO RIDGE WESTWARD BACK ACROSS PORTIONS OF THE AREA WATERS. THIS WILL MAKE THE WIND DIRECTION FORECAST A BIT TRICKY BASED ON THE POSITIONING OF THIS SFC RIDGE AXIS ACROSS THE LOCAL WATERS. AT THIS POINT...LOOKING AT AN ONSHORE FLOW DIRECTION THRU THIS PERIOD. A DECENT FETCH SHAPES UP WHEN THE CENTER OF THE SFC HIGH MOVES OFFSHORE FROM THE MID- ATLANTIC COAST. WILL LIKELY SEE THE INFLUENCE OF AN INCREASING E-SE GROUND SWELL ACROSS THE AREA WATERS BY LATE SUNDAY AND CONTINUING BEYOND. COULD RIP ACTIVITY INCREASE ACROSS AREA BEACHES...ESPECIALLY LATE IN THIS PERIOD. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 200 AM FRIDAY...SFC RIDGING FROM THE RETREATING SFC HIGH TO THE HIGH SEAS OF THE ATLANTIC...TO CONTINUE TO EXTEND ACROSS THE FA. THIS WILL KEEP MAINLY AN ONSHORE TRAJECTORY TO THE SFC WIND FIELD. A POSSIBLE NEW PLAYER TO THE MARINE FORECAST COMES IN THE FORM OF A WEAK TO MODEST UPPER LOW AND ITS SFC LOW COUNTERPART...MOVING WESTWARD ACROSS THE ATLANTIC HIGH SEAS. THIS COULD THROW A WRINKLE IN THE EXTENDED FORECAST DEPENDING HOW CLOSE IT COMES TO THE LOCAL WATERS DURING THE LATER PERIODS. RIGHT NOW...WILL INDICATE AN INCREASE TO THE SIGNIFICANT SEAS DUE THIS BUILDING E-SE GROUND SWELL. WILL KEEP BOTH WINDS/SIGNIFICANT SEAS JUST BELOW SCEC/SCA CRITERIA BUT LIKELY WILL HIGHLIGHT ITS POSSIBILITY IN THE HAZARDOUS WX OUTLOOK. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...RJD SHORT TERM...DCH LONG TERM...DCH AVIATION...43

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