Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 202354 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 754 PM EDT WED MAY 20 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 700 PM WEDNESDAY...THE SEA BREEZE HAS BEEN PUSHED WELL INLAND THIS AFTERNOON AND LIKELY TO PUSH EVEN FURTHER INLAND BEYOND THE ILM CWA THE REMAINDER OF THIS EVENING. IN ITS WAKE...A SHALLOW SFC BASED STABLE MARINE LAYER TO EXIST FOR THE REMAINDER OF THIS EVENING...WITH SOME MODIFICATIONS TO THIS LAYER OVERNIGHT. LATEST CONVECTION ACROSS THE FA HAS BASICALLY FELL APART DUE TO THE MARINE INFLUENCE. WILL ONLY CARRY 20 POPS AT MOST FOR THIS EVENING...MAINLY FOR RESIDUAL ONGOING CONVECTION AND FOR THE SLOW EASTWARD MOVING CONVECTION ACROSS INLAND SC...THAT MAY REACH THE FAR SW PORTIONS 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 WAIT FOR THE NEXT UPDATE AND DECIDE WHETHER TO INCLUDE OVERNIGHT FOG. LATEST MIN TEMP FORECAST LOOKS AOK. && .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 /00Z WEDNESDAY THROUGH MONDAY/... AS OF 00Z...SHOWERS AND THUNDERSTORMS HAVE MOSTLY ENDED LOCALLY...BUT A BRIEF SHOWER STILL CANNOT BE RULED OUT DURING THE NEXT HOUR ESPECIALLY AT ILM. OTHERWISE MOST OF THE NIGHT WILL BE DRY...BUT AGAIN A FEW SHOWERS MAY DEVELOP OFFSHORE AND ADVECT INTO ILM LATE TONIGHT TOWARDS THURSDAY MORNING. BIGGER CHALLENGE TONIGHT IS FOG/STRATUS POTENTIAL. A WAVE OF LOW PRESSURE WILL DEVELOP WEST OF THE AREA AND MOVE EAST OVERNIGHT. THE GRADIENT WILL REMAIN RELATIVELY WEAK...BUT SURFACE WINDS ARE NOT EXPECTED TO FULLY GO CALM AND MAY REMAIN OVER 5 KTS AT THE COAST. STILL...THE GROUND IS SATURATED AND DEWPOINTS HAVE RISEN QUITE A BIT BEHIND THE SEA BREEZE. AS TEMPS COOL TOWARDS THE DEWPOINT...THIS WILL COMBINE WITH THE WET GROUND TO PRODUCE FOG POTENTIAL...BUT AT THE SAME TIME WINDS AT 1500-2000 FT WILL INCREASE TO 15-20 KTS. THIS IS LIKELY NOT ENOUGH TO INHIBIT FOG ENTIRELY...BUT EXPECT PRIMARILY MVFR VSBYS. SOME IFR IS POSSIBLE AT KCRE FOR LOCAL EFFECTS...WITH A BETTER CHANCE AT KFLO/KLBT...BUT EVEN THERE HAVE CAPPED VSBY REDUCTION ABOVE IFR. ON THURSDAY...LOW PRESSURE WILL MOVE EAST AND DRAG A COLD FRONT ACROSS THE AREA AT THE END OF THE VALID PERIOD. SW WINDS AHEAD OF THE FRONT WILL GUST OVER 20 KTS 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. EXTENDED OUTLOOK...VFR. FOG POSSIBLE MONDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 700 PM WEDNESDAY...A MEANDERING FRONTAL BOUNDARY TO EXIST AND OCCUR ACROSS PORTIONS OF THE ILM NC AND SC WATERS THIS EVENING AND TONIGHT. THIS SFC PRESSURE PATTERN COULD MAKE THE WIND DIRECTION FORECAST A BIT CHALLENGING. THIS ESPECIALLY TRUE...WITH LATEST WIND DIR AND SPEED OBSERVATIONS ACROSS THE LOCAL AND OFFSHORE WATERS NOT LINING UP WHERE THE LATEST MODELS PLACE THE FRONT AT THIS TIME. IE. 41013 REPORTED WEST 10 KT OR LESS. AS A RESULT...WILL BACK DOWN ON THE OVERNIGHT EASTERLY WINDS ACROSS THE ILM WATERS NORTH OF CAPE FEAR. IN ADDITION...NOT MUCH OF A SFC PG ON EITHER SIDE OF THE FRONTAL BOUNDARY OVERNIGHT...WITH AROUND 10 KT LIKELY TO COVER WIND SPEEDS. THE APPROACHING LOW FROM THE INLAND CAROLINAS LATE TONIGHT WILL INCREASE THE WIND SPEEDS 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/RAN LONG TERM...SGL AVIATION...JDW

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