Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 210545 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 140 AM EDT THU MAY 21 2015 .SYNOPSIS... DEVELOPING LOW PRESSURE WILL SWEEP ACROSS NORTH CAROLINA ON THURSDAY PUSHING A COLD FRONT OFFSHORE BY THURSDAY EVENING. HIGH PRESSURE WILL BUILD IN FROM THE NORTH FRIDAY...BRINGING DRIER AIR INTO THE REGION OVER THE WEEKEND. THE HIGH WILL MOVE OFFSHORE SUNDAY INTO MONDAY BRINGING A RETURN OF HUMIDITY BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... AS OF 1030 PM WEDNESDAY...IN THE WAKE OF THE SEA BREEZE...WHICH TRAVELED ACROSS THE ENTIRE ILM CWA B4 DISSIPATING...A SHALLOW SFC BASED STABLE MARINE LAYER CONTINUES TO EXIST FOR THE REMAINDER OF THIS EVENING...WITH SOME MODIFICATIONS TO THIS LAYER OVERNIGHT. LATEST CONVECTION ACROSS THE FA CONTINUES TO FALL APART DUE TO THE MARINE INFLUENCE. WILL ONLY CARRY 20 POPS AT MOST FOR THE REMAINDER OF THIS EVENING...MAINLY FOR POSSIBLE CONVECTION THAT MAY AFFECT THE SOUTHERN 1 TO 2 THIRDS OF THE ILM CWA. FOR THE PRE- DAWN THU HOURS...LOOKS LIKE ENOUGH SUBSIDENCE ALOFT TO EXIST ACROSS THE FA BETWEEN THE EXITING MID-LEVEL S/W TROF TO THE EAST AND THE APPROACHING MID-LEVEL S/W TROF FROM THE WEST. HOWEVER...WITH A STALLED/MEANDERING FRONTAL BOUNDARY IN THE VICINITY OR ACROSS THE FA...WILL STILL CARRY A LOW CHANCE POP. WILL INCLUDE OVERNIGHT PATCHY FOG MAINLY ACROSS LOCATIONS THAT RECEIVED OR WILL RECEIVE RAINFALL. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... AS OF 300 PM WEDNESDAY...BY MID-MAY STANDARDS A PRETTY DYNAMIC SYSTEM WILL MOVE THROUGH NORTH CAROLINA THURSDAY. SURFACE LOW PRESSURE NEAR CHARLOTTE AT SUNRISE WILL MOVE EAST-NORTHEASTWARD TO THE OUTER BANKS BY EARLY EVENING. THIS LOW WILL BE SUPPORTED BY A SW-NE ALIGNED 300 MB JET STREAK ALONG THE MID- ATLANTIC COAST. 0-6 KM BULK SHEAR WILL INCREASE TO 20-25 KT ACROSS SC TO 30-40 KT ACROSS NC. 0-1 KM HELICITY WILL ALSO INCREASE AS YOU MOVE NORTHWARD...AIDED BY LOCALIZED BACKING OF THE LOW-LEVEL FLOW IN PROXIMITY TO THE SURFACE LOW. WHILE IT APPEARS THE BEST JUXTAPOSITION OF SHEAR...INSTABILITY AND LOW-LEVEL CONVERGENCE WILL OCCUR ALONG THE PATH OF THE SURFACE LOW JUST NORTH OF LUMBERTON... ELIZABETHTOWN AND WILMINGTON...UNDOUBTEDLY THERE WILL BE SCATTERED THUNDERSTORMS DEVELOPING SOUTH OF THE LOW WHERE CAPE AS HIGH AS 2000 J/KG COULD DEVELOP DURING THE DAY. MY FORECAST POPS THURSDAY RANGE FROM 40-50 PERCENT FROM LBT EAST TO BURGAW...WITH LOWER POPS (20-30 PERCENT) TO THE SOUTH. A BELT OF STRONG 700 MB WINDS (40 KT) SHOULD ADVECT ACROSS THE AREA DURING THE AFTERNOON. THIS AIR WILL BE QUITE DRY...AND FOR ANY STORMS ABLE TO DEVELOP THIS SHOULD ENHANCE THEIR ABILITY TO PRODUCE DAMAGING WINDS. 12Z MODELS ARE PRETTY CONSISTENT WITH THEIR DEPICTION OF WHERE THE LOW SHOULD TRACK. HOWEVER THE 00Z ECMWF WAS ~50 MILES FARTHER SOUTH WHICH WOULD SHIFT THE BEST POTENTIAL FOR STORMS INTO THE BENNETTSVILLE-WHITEVILLE-WILMINGTON CORRIDOR. A FIRST-GLANCE AT THE NEW 12Z ECMWF SHOWS IT NOW HAS THE LOW TRACKING ALMOST AS FAR NORTH AS THE 12Z GFS/NAM MODELS...HOPEFULLY KEEPING THE CORRIDOR OF BEST SEVERE WEATHER POTENTIAL JUST TO OUR NORTH. THURSDAY NIGHT AND FRIDAY SHOULD BE QUIET AND UNEVENTFUL AS DRIER AND COOLER AIR ARRIVES ON NORTHERLY WINDS. SURFACE HIGH PRESSURE CENTERED TO OUR WEST WILL BUILD IN THROUGH THE WEEKEND. I HAVE ADJUSTED FORECAST TEMPERATURES DOWNWARD BY A FEW DEGREES AS LATEST MODELS SHOW NEAR-IDEAL RADIATIONAL COOLING CONDITIONS OCCURRING IN AN UNSEASONABLY CHILLY AIRMASS. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... AS OF 300 PM WEDNESDAY...WITH DRY SFC HIGH PRESSURE AND DECENT RIDGING IN PLACE...EXPECT A FAIRLY QUIET PERIOD INTO EARLY NEXT WEEK. WILL SEE A GRADUAL INCREASE OF TEMPERATURES THROUGH THE MEMORIAL DAY WEEKEND FROM LOW/MID 80S TO MID/UPPER 80S ON MONDAY...WITH OVERNIGHT LOWS IN THE LOW TO MID 60S. AS SFC HIGH PRESSURE BEGINS TO SHIFT OFFSHORE...WILL SEE A NICE MOISTURE RETURN BEGINNING AS EARLY AS MONDAY. WITH HIGH TEMPERATURES IN THE MID TO UPPER 80S ON TUESDAY AND INCREASING HUMIDITY...COULD SEE SOME ISOLATED TO SCATTERED SHOWERS IN THE AFTERNOON HOURS...WITH A THUNDERSTORM POSSIBLE...MAINLY INLAND. INTO WEDNESDAY...PRECIPITABLE WATER VALUES INCREASE TO OVER ONE AND A HALF INCHES...AND AHEAD OF AN APPROACHING COLD FRONT ON WEDNESDAY. TIME OF ARRIVAL OF THE FRONT ITSELF IS HARD TO DETERMINE ATTM AS SOME GUIDANCE SUGGESTS ITS PROGRESSION MAY SLOW DOWN GIVEN WEAK RIDGING STILL IN PLACE. FOR NOW HAVE CONTINUED SLIGHT CHANCE FOR SHOWERS/THUNDERSTORMS ON WEDNESDAY. WITH OVERNIGHT LOWS INTO WEDNESDAY MORNING IN THE UPPER 60S...WILL SEE HIGH TEMPERATURES IN THE MID 80S ALONG THE COAST...AND UPPER 80S INLAND...WITH A FEW SPOTS POTENTIALLY HITTING 90 DEGREES. && .AVIATION /06Z THURSDAY THROUGH MONDAY/...
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AS OF 06Z...SHOWERS AND THUNDERSTORMS WERE LARGELY OFFSHORE... ALTHOUGH AN ISOLATED SHOWER HAS DEVELOPED WEST OF INTERSTATE 95. GUIDANCE STILL INSISTING THAT CONVECTION WILL DEVELOP OFFSHORE AND ADVECT ON SOUTHERLY WINDS INTO KILM. HAVE MAINTAINED TEMPO -SHRA TOWARDS DAWN FOR THIS ONE TERMINAL. TOUGHER CHALLENGE CONTINUES TO BE FOG/STRATUS POTENTIAL OVERNIGHT. GROUND IS SATURATED AND DEWPOINT DEPRESSIONS ARE TRENDING TOWARDS ZERO. DO NOT EXPECT WIDESPREAD OR DENSE FOG OVERNIGHT THANKS TO SURFACE WINDS THAT WON`T FULLY DECOUPLE NEAR THE COAST...AND A LLJ RISING TOWARDS 20 KT. HOWEVER...ENOUGH NEAR-SURFACE SATURATION IS STILL EXPECTED FOR SOME MVFR FOG...AT KCRE FOR LOCAL EFFECTS...AND KFLO/KLBT THANKS TO LIGHTER WINDS. KFLO PROBABLY HAS THE BEST CHANCE FOR IFR OVERNIGHT...BUT HAVE KEPT VSBYS JUST ABOVE IFR THRESHOLDS SINCE FORECAST PROFILES SUGGEST JUST A VERY SHALLOW SATURATED LAYER...WHICH COMBINED WITH THE INCREASING WINDS ABOVE THE INVERSION SHOULD PRECLUDE DENSE FOG. PATCHY LOW STRATUS AT KILM IS NOT EXPECTED TO BECOME A CEILING THROUGH SUNRISE. ON THURSDAY...LOW PRESSURE WILL MOVE EAST AND DRAG A COLD FRONT ACROSS THE AREA. SW WINDS AHEAD OF THE FRONT WILL GUST OVER 20 KT AT ALL TERMINALS...AND THUNDERSTORMS ARE POSSIBLE IN THE AFTN/EVE. HAVE NOT MENTIONED ANY TS ATTM...BUT WILL LIKELY SEE AT LEAST SCATTERED STORMS...FAVORED AT KLBT/KILM...WHICH MAY NEED A TAF MENTION WITH LATER ISSUANCES. COLD FRONT WILL CROSS OFFSHORE THURSDAY NIGHT TURNING WINDS TO THE NORTH BY THE END OF THE VALID PERIOD. EXTENDED OUTLOOK...VFR. FOG POSSIBLE MONDAY.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1030 PM WEDNESDAY...A MEANDERING FRONTAL BOUNDARY TO EXIST AND OCCUR ACROSS PORTIONS OF THE ILM NC AND SC WATERS THIS EVENING AND OVERNIGHT. THIS SFC PRESSURE PATTERN COULD MAKE THE WIND DIRECTION FORECAST A BIT CHALLENGING. WILL CONTINUE TO DOWNPLAY THE OVERNIGHT EASTERLY WINDS ACROSS THE ILM WATERS NORTH OF CAPE FEAR...AND TRANSITION TO A S TO SW DIRECTION. IN ADDITION...NOT MUCH OF A SFC PG ON EITHER SIDE OF THE FRONTAL BOUNDARY OVERNIGHT...WITH AROUND 10 KT LIKELY TO COVER OVERNIGHT WIND SPEEDS. THE APPROACHING LOW FROM THE INLAND CAROLINAS LATE TONIGHT WILL INCREASE THE WIND SPEEDS MAINLY AFTER THIS PERIOD. SIGNIFICANT SEAS WILL BASICALLY RUN 2 TO 3 FT...AND BE COMPRISED OF BOTH WEAK WIND DRIVEN WAVES AT 4 TO 5 SECOND PERIODS...AND A LAZY 1 TO 1.5 FOOT GROUND SWELL AT 8 TO 9 SECOND PERIODS. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 PM WEDNESDAY...LOW PRESSURE WILL MOVE EASTWARD THROUGH NORTH CAROLINA THURSDAY...BRINGING A BELT OF SOUTHWEST 15-20 KT WINDS THROUGH THE AREA. A COLD FRONT WILL DIP SOUTH BEHIND THE DEPARTING LOW THURSDAY EVENING...WITH NORTHERLY WINDS EXPECTED THROUGH FRIDAY. THE STRONGEST NORTH WINDS ARE EXPECTED THURSDAY NIGHT INTO EARLY FRIDAY WITH 15-20 KT POSSIBLE AT TIMES. THESE PERIODS OF RELATIVELY STRONG WINDS SHOULD LAST LESS THAN 12 HOURS EACH...AND THEREFORE SEAS ARE EXPECTED TO REMAIN BELOW 5 FEET. LONG TERM /SATURDAY THROUGH MONDAY/... AS OF 330 PM WEDNESDAY...HIGH PRESSURE WILL RESULT IN NE WINDS OF 10 TO 15 KT SATURDAY WHICH WILL VEER TO THE SE BY SUNDAY NIGHT. SEAS OF 3 FT OR LESS ARE ON TAP FOR THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...DCH SHORT TERM...TRA LONG TERM...SGL AVIATION...JDW/RJD

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