Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 290527 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 127 AM EDT MON SEP 29 2014 .SYNOPSIS... HIGH PRESSURE WILL SLOWLY WEAKEN ACROSS THE AREA AS A LOW PRESSURE SYSTEM DEVELOPS ALONG THE GULF COAST. THIS LOW PRESSURE WILL MOVE JUST SOUTH OF THE AREA THROUGH TUESDAY...BRINGING A GOOD CHANCE FOR RAIN EARLY IN THE WEEK. HIGH PRESSURE WILL BUILD IN BEHIND DEPARTING LOW PRESSURE THROUGH MID WEEK. A COLD FRONT WILL MOVE ACROSS THE CAROLINAS FRIDAY INTO SATURDAY WITH COOL AND DRY HIGH PRESSURE BUILDING IN FOR THE LATTER PART OF THE WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... AS OF 945 PM...RAISED POPS TO LIKELY FAR SW FOR THE NEXT TWO TO THREE HOURS DUE TO ACTIVITY COMING IN FROM THE SOUTHEAST. ALSO TWEAKED MINS UPWARD A DEGREE OR TWO...ESPECIALLY NW DUE TO CLOUD COVER AND DEWPOINTS ABOVE FORECAST MINS. OVERALL THOUGH...PREVIOUS FORECAST REMAINS ON TRACK. DISCUSSION FROM 3 PM FOLLOWS. BROAD...DIFFUSE AREA OF HIGH PRESSURE TO THE NORTH WILL FURTHER WEAKEN AS AN H/5 LONGWAVE TROUGH DROPS SE ACROSS EASTERN CONUS. FRONTOGENESIS JUST OFF THE SOUTHEASTERN US COAST AND RESULTING ISENTROPIC LIFT IN COMBINATION WITH INCREASING MOISTURE ADVECTION WILL GRADUALLY INCREASE THE CHANCES OF PRECIPITATION IN THE FORM OF STRATIFORM RAIN OVERNIGHT. BEST CHANCES WILL BE TOWARDS DAYBREAK WITH MOST PLACES REMAINING DRY THROUGH THEN. UNTIL THEN...RADAR LOOPS AND LATEST GUIDANCE INDICATE A FEW SHORT-LIVED SHOWERS MAY MOVE ASHORE THIS AFTERNOON AND EVENING. MODEL SOUNDINGS SHOW ATMOSPHERIC COLUMN NEARLY SATURATED BY DAYBREAK WITH CLOSE TO 2 INCHES P/W SO EXPECT EXTENSIVE CLOUDINESS TO DEVELOP OVERNIGHT. LEANED TOWARDS THE RECENTLY BETTER-PERFORMING LAV GUIDANCE FOR OVERNIGHT MINIMUMS...ALTHOUGH IN FACT ALL MOSS NUMBERS FROM THE VARIOUS MODELS WERE VERY CLOSELY CLUSTERED. THIS WILL GIVE US LOWS IN THE MID 60S MOST PLACES. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...FORECAST CHALLENGE FOR EARLY WEEK REVOLVES AROUND A LOW PRESSURE SYSTEM WHICH WILL SKIRT JUST SOUTH OF THE CWA LATE MONDAY INTO TUESDAY. WHILE THE LOW PRESSURE ITSELF WILL DEVELOP OVER THE GULF OF MEXICO MONDAY AND PASS SOUTH OF THE AREA...INCREASING MOIST ADVECTION...ISENTROPIC LIFT ATOP THE SURFACE WEDGE...AND PVA AHEAD OF A SOUTHERN STREAM VORT LOBE...WILL ALL ACT TOGETHER TO PRODUCE RAINFALL LOCALLY. THE BEST RAINFALL CHANCES ARE EXPECTED BETWEEN MONDAY AFTN AND VERY EARLY TUESDAY MORNING...BEFORE THE LOW PRESSURE PULLS OFF TO THE NORTHEAST. WHILE LIKELY POP HAS BEEN INHERITED...WILL SHIFT THE AXIS OF HIGHEST POP/QPF TO THE PEE DEE AND GRAND STRAND REGION WHICH WILL FEATURE BETTER OVERALL FORCING AND HIGHER COLUMN MOISTURE. PWATS WILL BE AROUND 2 INCHES MONDAY NIGHT AS THE SYSTEM MAKES ITS CLOSEST APPROACH...BEFORE FALLING RAPIDLY TO LESS THAN 1 INCH TUESDAY NIGHT. AS THE SYSTEM PULLS AWAY ON TUESDAY...IT WILL INTERACT WITH INCREASING BAROCLINICITY OFFSHORE AS WELL AS A SECONDARY NORTHERN STREAM VORT IMPULSE...TO STRENGTHEN...AND NORTHERLY WINDS MAY STEADILY INCREASE THROUGH THE AFTN. TEMPS MONDAY WILL BE LIMITED BY INCREASING CLOUD COVER AND SHOWERS...SO EXPECT HIGHS IN THE MID 70S WITH LOWS AT NIGHT FALLING ONLY INTO THE MID 60S. MORE SUNSHINE ON TUESDAY WILL ALLOW HIGHS TO RISE A DEGREE OR TWO WARMER THAN MONDAY EVEN WITH WEAK COOL ADVECTION...BUT LOWS WILL LIKELY BE A BIT COOLER THANKS TO THE DRYING COLUMN. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 300 PM SUNDAY...THE EXTENDED FORECAST REMAINS STABLE WITH REGARDS TO SIGNIFICANT WEATHER SYSTEMS...WHICH ARE MINIMAL FOR OUR AREA. WEDNESDAY AND THURSDAY WILL SEE MODEST RIDGING MOVING ACROSS THE TENNESSEE VALLEY AS SURFACE HIGH PRESSURE BUILDS DOWN IN FROM THE NORTHEAST. THIS PATTERN QUICKLY BREAKS DOWN FRIDAY AS A DEEP TROUGH DEVELOPS IN THE LEE OF THE ROCKIES AND MOVES QUICKLY EAST. THE ATTENDANT COLD FRONT REMAINS ON SCHEDULE FOR A LATE FRIDAY/EARLY SATURDAY PASSAGE. THE DEEP TROUGH TO THE NORTH CENTERED AROUND THE GREAT LAKES WILL HAVE LITTLE IF ANY GULF OF MEXICO MOISTURE TO WORK WITH SO POPS REMAIN IN THE LOW CHANCE RANGE. PROBABLY THE MOST INTERESTING ASPECT OF THE EXTENDED IS THE SOUTHERN REACH IN THE WAKE OF THE FRONT OF THE ZERO 850MB ISOTHERM...DROPPING DOWN TO THE CENTRAL APPALACHIANS. WE HAVE WIDESPREAD 50S FOR LOWS SUNDAY..OTHERWISE NO CHANGES TO THE TEMPERATURE TRENDS PRE FRONT...A FEW DEGREES ABOVE CLIMATOLOGY. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 06Z...POTENTIAL FOR MVFR ACROSS THE AREA DUE TO AREAS OF LOW CIGS AND PATCHY FOG OVERNIGHT...WITH MVFR/IFR POSSIBLE ON MONDAY DUE TO LOW CIGS...AREAS OF FOG...AND MODERATE RAIN AT TIMES. WITH VFR PREVAILING AND LIGHT WINDS...LATEST SATELLITE IMAGERY CONTINUES TO ILLUSTRATE INCREASING CLOUDS ACROSS THE AREA. COULD SEE DETERIORATION OF CONDITIONS TO MVFR AS LOW CIGS LINGER ABOUT THE AREA WITH DEVELOPMENT OF PATCHY FOG. INTO THE EARLY MORNING HOURS...MVFR ALONG WITH THE POTENTIAL FOR IFR WILL SET UP AS LOW CIGS...AREAS OF FOG...AND ISOLATED SHOWERS BEGIN TO MOVE ACROSS THE AREA. THOUGH WILL NOTE THAT IT IS ANTICIPATED FOR INCREASED COVERAGE IN RAINFALL TO BECOME MORE PROMINENT INTO THE AFTERNOON HOURS AND PERSIST THROUGH THE REMAINDER OF THE VALID TAF PERIOD. EXPECT NORTHEAST WINDS AOB 10 KTS TO PREVAIL...BECOMING LIGHT TOWARDS MONDAY NIGHT. EXTENDED OUTLOOK...IMPROVING CONDITIONS ON TUESDAY AS LOW PRESSURE BEGINS TO MOVE AWAY FROM THE REGION. VFR WEDNESDAY AND THURSDAY WITH A SLIGHT CHANCE FOR SHOWERS FRIDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 945 PM...PREVIOUS COASTAL WATERS FORECAST LOOKS GOOD. DISCUSSION FROM 3 PM FOLLOWS. BROAD...WEAK HIGH PRESSURE NORTH OF THE AREA COMBINED WITH A DEVELOPING FRONT OFFSHORE WILL KEEP A LIGHT...GRADUALLY DECREASING NORTHEASTERLY FLOW THROUGH THE PERIOD. EXPECT NE WINDS OF 10 TO 15 KTS THIS AFTERNOON DECREASING TO AROUND 10 KTS OVERNIGHT. SEAS WILL DECREASE FROM 3 TO 4 FT THIS AFTERNOON TO 2 TO 3 FT OVERNIGHT. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 PM SUNDAY...LOW PRESSURE MOVING SOUTH OF THE AREA WILL PUSH OFF THE COAST TUESDAY MORNING...WHILE HIGH PRESSURE CONTINUES TO RIDGE DOWN THE COAST FROM NEW ENGLAND. THIS PRODUCES NE WINDS OF 10-15 KTS MOST OF THE PERIOD...BUT AS THE LOW PULLS AWAY LATE TUESDAY...IT WILL STRENGTHEN...AND CAUSE WINDS TO INCREASE TO 15-20 KTS AND BACK TO THE NORTH TUESDAY NIGHT. SEAS WILL BE 2-3 FT MONDAY AND THE BEGINNING OF TUESDAY ON THE NE WINDS...RISING STEADILY LATE TO 3-5 FT AS THE WINDS INCREASE ON THE BACK SIDE OF THE LOW PRESSURE SYSTEM. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 300 PM SUNDAY...A NORTHEASTERLY FLOW WILL CONTINUE WEDNESDAY AND MOST OF THURSDAY VIA HIGH PRESSURE EXTENDING DOWN FROM THE CANADIAN MARITIMES. THE GRADIENT ISN`T THAT STRONG AND WILL ONLY SEE A FEW HOURS OF 15-20 KNOTS EARLY WEDNESDAY. FROM THAT POINT ON...WINDS DIMINISH TO TEN KNOTS OR LESS BY LATE THURSDAY. FOR FRIDAY A MODEST SOUTHWESTERLY FLOW DEVELOPS AHEAD OF THE FRONT. SOME 4-5 FOOTERS APPEAR IN THE SPECTRUM WEDNESDAY ESPECIALLY ACROSS THE OUTER WATERS WITH THE STRONGER WINDS. FOR THURSDAY AND FRIDAY...SIGNIFICANT SEAS DROP TO 2-3 FEET. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...31 NEAR TERM...31 SHORT TERM...JDW LONG TERM...SHK AVIATION...SGL/SRP

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