Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 180548 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 147 AM EDT FRI APR 18 2014 .SYNOPSIS... HIGH PRESSURE WILL LINGER ACROSS THE CAROLINAS TODAY THROUGH FRIDAY. RAIN CHANCES WILL INCREASE DURING THE WEEKEND AS A LOW PRESSURE SYSTEM MOVES FROM THE GULF OF MEXICO AND INTO THE ATLANTIC OCEAN. A WEAK PRESSURE PATTERN WILL SETTLE OVER THE CAROLINAS FOR MUCH OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 1105 PM THURSDAY...LATEST IR SAT IMAGERY...THE 11-3.9 MICRON CHANNEL...TRENDS INDICATE CONTINUED MAINLY THIN CIRRUS HAVING SPREAD ACROSS THE FA...FROM SW TO NE. A FEW SFC OBS INDICATE MID- LEVEL AS/AC EXISTS JUST OUTSIDE THE ILM CWA IN CAE AND CHS FORECAST AREAS. EXPECT THE MID-LEVEL CLOUDS TO PUSH OVERHEAD OVERNITE...ALONG WITH STRATOCU JUST OFFSHORE BEGINNING TO PARTIALLY MOVE ONSHORE OVERNIGHT. OVERALL TREND OF INCREASING AND THICKENING CLOUDINESS DURING THE OVERNIGHT PERIOD STILL AOK. RAIN CHANCES AND POPS HAVE BEEN DEFERRED TO DAYLIGHT FRIDAY...MAINLY LATER FRI MORNING AND AFTERNOON. TEMPS HAVE NEARLY STABILIZED NOW...HOWEVER WILL CONTINUE WITH A SLOW DECREASING TEMP TREND OVERNIGHT UNTIL THICKER AND MORE WIDESPREAD CLOUDINESS OVER SPREADS THE AREA AND COUNTERING ANY BRIEF RAD COOLING THAT OCCURRED EARLY THIS EVENING. WINDS REMAIN ACTIVE...JUST NOT AS ACTIVE LIKE EARLIER DISCUSSED. LOOKING AT 5 MPH OR LESS...EXCEPT 5 TO 10 MPH ACROSS COASTAL AREAS. OVERALL...ACTIVE WIND FIELD TO PREVENT TEMPS FROM DROPPING TOO QUICKLY. PREVIOUS DISCUSSION............................................... AS OF 3:00 PM THURSDAY...HIGH PRESSURE WEDGED ACROSS THE INTERIOR CAROLINAS HAS WEAKENED SLIGHTLY THROUGH THE DAY...AND THIS TREND WILL CONTINUE OVERNIGHT. THE 850-500 MB LAYER WILL REMAIN QUITE DRY THROUGH THE OVERNIGHT PERIOD...HOWEVER UPPER-LEVEL MOISTURE WILL BE ON THE INCREASE AHEAD OF A MID-LEVEL TROUGH SWEEPING ACROSS THE PLAINS. DEWPOINTS HAVE SURGED INTO THE LOW-MID 40S AS OF 18Z. THIS IS A FASTER RECOVERY OVER THE NORTHWESTERN TIER THAN WAS PROGGED BY MOS...SO HAVE MADE SOME SLIGHT UPWARD ADJUSTMENTS TO MIN TEMPS IN THAT AREA. GENERALLY A RANGE OF 43-49 EXPECTED ACROSS THE CWA TONIGHT. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... AS OF 3:00 PM THURSDAY...AN UPPER TROUGH WITH AN EMBEDDED AND GRADUALLY DEEPENING LOW CENTER WILL MOVE EAST ACROSS THE GULF COAST STATES THROUGH THE SHORT TERM. THIS FEATURE WILL DRIVE A DEVELOPING SURFACE LOW AND ITS ASSOCIATED FRONTAL SYSTEM FROM THE GULF OF MEXICO ACROSS FLORIDA ON FRIDAY AND ULTIMATELY INTO THE OPEN WATERS OF THE ATLANTIC ON SATURDAY. GUIDANCE STILL DIFFERS ON PLACEMENT AND DEVELOPMENT OF THIS SYSTEM SO ALTHOUGH I HAVE GONE WITH A BLEND OF GUIDANCE HAVE LEANED TOWARDS THE GFS/ECMWF SOLUTIONS...WHICH SEEMED MORE SIMILAR. WHICH MODELS ULTIMATELY VERIFY MAKES A SIGNIFICANT DIFFERENCE AS FAR AS POPS AND QPF GOES...WITH THE NAM BEING SIGNIFICANTLY THE DRYER SOLUTION. AS I HAVE FAVORED THE GFS/ECMWF SOLUTIONS...I AM NOW EXPECTING A SIGNIFICANT RAIN EVENT...WITH QPF EVENT TOTALS IN THE 1.0 TO 1.5 INCH RANGE. HEAVIEST RAIN WILL BE CENTERED AROUND FRIDAY NIGHT. COOL NORTHEAST FLOW WILL KEEP MAXIMUM TEMPERATURES IN THE BELOW NORMAL RANGE...WITH HIGHS IN THE MID 60S BOTH DAYS. EXTENSIVE CLOUD COVER WILL HELP KEEP MINIMUM TEMPERATURES ON THE MILD SIDE...WITH LOWS RANGING FROM THE UPPER 40S TO MID 50S BOTH DAYS. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 3:00 PM THURSDAY...CUTOFF UPPER LOW TRAVERSING FLORIDA ON SUNDAY. MODELS AT ODDS AS TO HOW FAR NORTH PRECIPITATION IS SPREADING. HOWEVER EVEN THE MORE SUPPRESSED GUIDANCE IMPLIES THAT COASTAL LOCATIONS SHOULD HAVE SOME SMALL RAIN CHANCES AND THE FCST HAS BEEN ADJUSTED ACCORDINGLY. THERE IS A POSSIBILITY HOWEVER THAT THIS WILL HAVE TO BE TRENDED UPWARDS BOTH WITH RESPECT TO POP VALUES AND NORTHERN EXTENT. THIS SYSTEM PROGRESSES EASTWARD BY MONDAY PAVING THE WAY FOR A DRIER AND MORE SEASONABLE AFTERNOON WITH A WEAK SURFACE PRESSURE PATTERN AND ZONAL MID LEVEL FLOW. BY TUESDAY THE STILL WEAK BL FLOW TURNS FROM NRLY TO SRLY BOOSTING TEMPS. AN UPPER LOW AND COLD FRONT APPEAR SLATED FOR TUESDAY NIGHT OR WEDNESDAY BUT IT SEEMS TOO MOISTURE-DEPRIVED TO YIELD MEANINGFUL RAIN CHANCES. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/...
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AS OF 06Z...WEDGE WILL HANG ON AT LEAST FOR THE NEXT 12 HOURS...BUT WILL BREAK DOWN AS LOW PRESSURE APPROACHES FRIDAY AFTERNOON. LOOK FOR SCATTERED SKIES OVERNIGHT WITH NO FOG EXPECTED DUE TO THE MOISTURE PROFILES AND THE FACT THAT THE WIND WILL LIKELY STAY ABOVE 6 KTS. THE GFS IS INTRODUCING STRATUS TOWARD MORNING BUT THINK THIS WILL BE A STRETCH AND WENT WITH SCATTERED. FRIDAY...INCREASING CLOUDS AS THE SYSTEM APPROACHES. STILL SOME UNCERTAINTY AS MODELS ARE NOT IN AGREEMENT. WEATHER WILL AFFECT THE SOUTHERN TERMINALS FIRST...WITH RAIN EXPECTED TO OVERSPREAD THE AREA BY 20-21Z...ONE TO THREE HOURS LATER FOR THE NORTHERN TERMINALS. DECENT ISENTROPIC LIFT SHOULD PRODUCE FAIRLY STEADY STRATIFORM PRECIP WITH LOWER CEILINGS TOWARD THE END OF THE FORECAST PERIOD. NORTHEAST WINDS WILL CONTINUE...GUSTY ON FRIDAY. EXTENDED OUTLOOK...EXPECT AT LEAST PERIODS OF MVFR/IFR CIGS FRIDAY EVENING AND SATURDAY. MVFR CIGS COULD LINGER WELL INTO SUNDAY. VFR ON MONDAY AND TUESDAY.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1100 PM THURSDAY...THE SCA CONTINUES THROUGH SUNDAY WHICH BASICALLY MATCHES UP WITH OUR NEIGHBORING WATERS. THE COMBINATION OF THE 1040+ MB HIGH CENTERED OVER THE NE STATES AND DEVELOPING LOW PRESSURE OVER THE NE GULF OF MEXICO...WILL RESULT IN A TIGHTENED SFC PRESSURE GRADIENT OVERNIGHT THROUGH FRIDAY...AND LIKELY WELL INTO THE WEEKEND. WIND SPEEDS TO RANGE BETWEEN 15 TO 25 KT OVERNIGHT. THE PROGGED SFC PRESSURE PATTERN WILL YIELD A NE TO ENE WIND DIRECTION. MODELS INDICATE A SFC COASTAL TROF THAT WILL DEVELOP LATER OVERNIGHT JUST OFFSHORE... AND ORIENTED NE TO SW. THIS MAY ENHANCE WIND SPEEDS ACROSS THE LOCAL WATERS AS WELL AS BE A FOCUS FOR PCPN DEVELOPMENT LATER ON FRIDAY. SIGNIFICANT SEAS TO REMAIN IN THE 4 TO 7 FT RANGE OVERNIGHT...WITH THE HIGHEST SEAS ACROSS THE LOCAL WATERS OFF CAPE FEAR...AND OFF CAPE ROMAIN. AN EASTERLY 2 TO 3 FOOT GROUND SWELL IN THE 9 TO 10 SECOND PERIOD RANGE WILL REMAIN ACTIVE. HOWEVER...THE NE WIND DRIVEN WAVES WILL DOMINATE THE SEAS SPECTRUM WITH AVERAGE PERIODS IN THE 5.5 TO 6.5 SECOND RANGE. PREVIOUS DISCUSSION........................................... AS OF 3:00 PM THURSDAY...A RELATIVELY STRONG PRESSURE GRADIENT WILL PERSIST ACROSS THE COASTAL WATERS THROUGH THE NIGHT BETWEEN A STATIONARY SURFACE TROUGH WELL OFFSHORE AND A WEDGE OF HIGH PRESSURE INLAND. THE WEDGE WILL WEAKEN SLIGHTLY OVERNIGHT...HOWEVER THIS WILL RESULT IN VERY LITTLE CHANGE TO THE STRENGTH OF THE GRADIENT AS SURFACE PRESSURES FALL OVER THE NORTHERN GULF OF MEXICO. NORTHEAST WINDS ARE EXPECTED TO REMAIN IN A 15-20 KT RANGE WITH SOME GUSTS TO 25 KTS...AND THIS WILL KEEP SEAS OVER THE SMALL CRAFT ADVISORY THRESHOLD THROUGH THE DURATION OF THE NIGHT. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3:00 PM THURSDAY...NORTHEAST FLOW WILL PERSIST THROUGH THE SHORT TERM AS A FRONTAL SYSTEM EXITS THE GULF OF MEXICO AND MOVES INTO THE OPEN WATERS OF THE ATLANTIC. WILL EXTEND THE SMALL CRAFT ADVISORY THROUGH FRIDAY NIGHT AS MODERATE NORTHEASTERLY WINDS WILL KEEP SEAS IN THE 4 TO 6 FT RANGE. ANTICIPATE THAT WE WILL FURTHER EXTEND THE SCA INTO SATURDAY AS CONDITIONS ARE EXPECTED TO FURTHER DETERIORATE WITH A DEEPENING LOW PRESSURE SYSTEM MOVING INTO THE ATLANTIC. LONG TERM /SUNDAY THROUGH MONDAY/... AS OF 3:00 PM THURSDAY...SMALL CRAFT ADVISORY LIKELY IN EFFECT FOR MOST OF THE PERIOD. GRADIENT WILL BE PINCHED BY A SLOW MOVING LOW WHOSE UPPER LOW IS CUT OFF FROM THE MAIN JET STREAM FLOW. THIS FEATURE PAIRED WITH A FAIRLY STRONG HIGH OFF NEW ENGLAND COAST WILL LEAD TO STRONG WINDS THAT MAY EVEN OCCASIONALLY GUST TO GALE FORCE ON SUNDAY OR SUNDAY NIGHT. ABATING TREND ON MONDAY WILL BE GRADUAL DUE TO THE SLOW MOVEMENT OF THE SYSTEM. WINDS DROP OFF MORE SUBSTANTIALLY MONDAY NIGHT AS IT GETS CAUGHT BACK UP IN THE JET AND ACCELERATES EASTWARD. FLAGS WILL BE ABLE TO BE DROPPED SOME TIME LATE MONDAY. TUESDAY BRINGS LIGHT WINDS THAT WILL BE BACKING AND THERE WILL STILL BE A LITTLE BACKSWELL FROM THE SYSTEM AS IT CONTINUES TO MOVE EAST OUT TO SEA. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SUNDAY FOR AMZ250-252-254- 256. && $$ SYNOPSIS...REK NEAR TERM...DCH/CRM SHORT TERM...REK LONG TERM...MBB AVIATION...DL

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