Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 080556 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 156 AM EDT TUE JUL 8 2014 .SYNOPSIS... WARMER THAN NORMAL TEMPERATURES THROUGH THE MID WEEK WILL BE ACCOMPANIED BY A GRADUAL INCREASE IN RAIN CHANCES. BETTER RAIN CHANCES COME THURSDAY AND FRIDAY AS A FRONT ENTERS AND STALLS OVER THE AREA. THESE RAIN CHANCES WILL DECREASE BUT ALSO LINGER INTO THE WEEKEND AS THE FRONT WEAKENS. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 2 AM TUESDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: CLOUD-WISE WE ARE LEFT WITH A LARGE CIRRUS CANOPY ACROSS THE INTERSTATE 95 CORRIDOR COURTESY OF EARLIER CONVECTION FROM FLORENCE SOUTHWARD TO ALMOST CHARLESTON. THIS SHOULD THIN AND DISSIPATE OVER THE NEXT 2-3 HOURS. WE ARE ALSO PICKING UP THE FIRST INDICATION OF SOME LOWER CUMULUS/STRATOCUMULUS DEVELOPING ALONG THE COAST WITH 1500-1600 FOOT CLOUD BASES NOW SHOWING UP ON OBSERVATIONS FROM NORTH MYRTLE BEACH AND SOUTHPORT. AS MID-70S DEWPOINTS CONTINUE TO STREAM ONSHORE THIS WILL PROBABLY SPREAD NORTHWARD TO ENCOMPASS WILMINGTON. NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST ON THIS WARM MUGGY SUMMER NIGHT. A COUPLE OF FORECAST UPDATES HAVE BEEN CREATED IN THE PAST FEW HOURS CONCERNING CONVECTION ACROSS NORTHEASTERN SOUTH CAROLINA. THE FIRST BATCH OF STORMS NEAR AND JUST WEST OF GEORGETOWN DROPPED A RADAR-ESTIMATED 4 INCHES OF RAIN WEST OF SAMPIT BEFORE DISSIPATING IN THE COOLER MARINE AIR BEHIND THE SEABREEZE. A SECOND CLUSTER OF THUNDERSTORMS ACROSS WILLIAMSBURG AND SOUTHERN FLORENCE COUNTIES HAS DROPPED A MORE WIDESPREAD 1 INCH RAIN FROM EAST OF LAKE CITY SOUTHWARD THROUGH KINGSTREE TO THE SANTEE RIVER. LATEST RAPID-UPDATE MODELS SUGGEST THESE STORMS WILL CONTINUE MOVING NE 15-20 KT THROUGH 00Z...THEN SHOULD RAPIDLY DIE AS THE BOUNDARY LAYER COOLS AND STABILIZES. STORMS THIS AFTERNOON AND THIS EVENING HAVE BEEN AIDED STEEP LAPSE RATES ALOFT AND A CONSIDERABLY WEAKER SUBSIDENCE INVERSION THAN THE MODELS WERE INDICATING A FEW DAYS AGO. A WEAK 500 MB DISTURBANCE ACROSS EASTERN SC PLUS A 200 MB JET STREAK EXTENDING FROM NE NORTH CAROLINA TO THE DELMARVA OFFSHORE WATERS IS ALSO HELPING BY PROVIDING UPPER DIVERGENCE/VENTILATION FOR THE STORMS...EASILY OBSERVED ON SATELLITE IMAGERY BY THE RAPIDLY EXPANDING DOWNWIND CIRRUS PLUMES. AS THE BOUNDARY LAYER DECOUPLES TONIGHT AND SURFACE WINDS DIMINISH...A LOW LEVEL JET WILL DEVELOP WITH 1000 FOOT WIND SPEEDS BUILDING TO 20 KNOTS. ENOUGH OF A GRADIENT SHOULD REMAIN TO KEEP SURFACE WINDS FROM BECOMING COMPLETELY CALM...AND WITH PLENTY OF LOW LEVEL MOISTURE REMAINING WE SHOULD NOT BE ABLE TO BUILD A SUBSTANTIAL RADIATIONAL INVERSION TONIGHT. LOWS SHOULD ONLY REACH THE 73-78 RANGE...WARMEST AT THE BEACHES TONIGHT. THE SOUTH-FACING BEACHES BETWEEN LITTLE RIVER AND CAPE FEAR MAY ONLY HAVE LOWS AROUND 80 TONIGHT AS WINDS BLOW ONSHORE OFF THE TROPICALLY-WARM OCEAN. && .SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...DESPITE A SOUTHERLY COMPONENT TO THE FLOW THROUGH A FAIRLY DEEP LAYER TUESDAY MUCH OF THE COLUMN REMAINS TOO DRY TO SUPPORT MEANINGFUL PRECIP CHANCES. WSW MID LEVEL FLOW JUST ISNT BACKED ENOUGH AND STILL IMPORTING FAIRLY DRY AIR EVEN AS LOW LEVELS MOISTEN. PIEDMONT TROUGH WILL BE DEVELOPING BUT LOOKS TO HAVE TOO LITTLE CONVERGENCE TO PROVIDE ANY LIFT. FINAL ARGUMENT AGAINST MENTIONABLE POPS IS THE DEPARTURE OF THE UPPER LOW CURRENTLY FIRING STORMS TO OUR WEST. TEMPERATURES EXPECTED TO BE ABOVE CLIMO BUT WRF MOS GUIDANCE HAS BACKED OFF ON THE MAGNITUDE OF THE HEAT. GIVEN THE LACK OF DECENT MID LEVEL RIDGING DID TRIM HIGHS A LITTLE...BUT NOT QUITE AS COOL AS WRF. STORMS TOUGHER TO RULE OUT ON WEDNESDAY WITH A SHARPENING OF THE PIEDMONT TROUGH AND A RIBBON OF MOISTURE APPROACHING FROM THE NORTHWEST. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 3 PM MONDAY...WEAKLY AMPLIFIED PATTERN AT THE START OF THE PERIOD WILL TRANSITION TO FLAT RIDGING FOR THE START OF NEXT WEEK. FIRST HALF OF THE PERIOD WILL BE MARKED BY SHOWERS AND THUNDERSTORMS AS WEAK COLD FRONT MOVES INTO THE AREA AND STALLS. DEEP MOISTURE AND DIURNAL HEATING IN CONJUNCTION WITH THE DECAYING FRONT WILL GENERATE AFTERNOON CONVECTION THU AND FRI. SURFACE BOUNDARY WEAKENS ON SAT AS MID LEVEL TROUGH FILLS AND LIFTS NORTHEAST. MID LEVEL DRY AIR MOVES INTO THE AREA IN THE WAKE OF THE TROUGH REDUCING SHOWER AND THUNDERSTORM CHANCES LATE SAT AND SUN. WEAK MID LEVEL RIDGING BUILDS OVER THE SOUTHEAST EARLY NEXT WEEK BUT THE LACK OF STRONG SUBSIDENCE AND AN INCREASE IN MID LEVEL MOISTURE ON MON WILL MAINTAIN CHANCES OF AFTERNOON CONVECTION THROUGH THE END OF THE PERIOD. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 06Z...EXPECT MAINLY VFR CONDITIONS OVERNIGHT WITH SOME TEMPO MVFR/IFR CIGS POSSIBLE IN THE 09-12Z TIME FRAME. SOUTHWEST WINDS WILL BE TOO STRONG FOR FOG FORMATION...BUT THE LOW LEVELS ARE MOIST ENOUGH TO SUPPORT EARLY MORNING STRATUS. TEMPO 1-2KFT MVFR CIGS CAN BE EXPECTED ALONG THE COAST...WHILE KFLO/KLBT MAY SEE BRIEF PERIODS OF IFR STRATUS AROUND DAYBREAK...THOUGH CONFIDENCE IS STILL LOW. SOUTHWEST WINDS AOB 10 KTS WILL STRENGTHEN LATER TODAY AS THE GRADIENT TIGHTENS OVER OUR AREA. S-SW WINDS 10-15 KTS DURING THE DAY WILL GUST TO 20-25 KTS DURING THE AFTERNOON HOURS...WITH HIGHEST WIND SPEEDS AT THE COASTAL TERMS. THE GUSTS WILL SUBSIDE IN THE EVENING HOURS...BUT SOUTHWEST WINDS 10-12 KTS WILL PERSIST THROUGH THE END OF THE TAF PERIOD. EXTENDED OUTLOOK...VFR SHOULD PREVAIL THROUGH THE EXTENDED PERIOD. INCREASING CHANCES FOR SHOWERS/TSTMS THURSDAY THROUGH SATURDAY WITH TEMPO MVFR POSSIBLE AS A FRONT STALLS OVER THE AREA. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 2 AM TUESDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: SOUTHWEST WINDS REMAIN IN THE 15-20 KNOT RANGE WITH SOME GUSTS AS HIGH AS 22 KNOTS REPORTED RECENTLY FROM OCEAN CREST PIER AT OAK ISLAND. THE NEARSHORE WRIGHTSVILLE BEACH BUOY IS REPORTING A SOLID 3 FOOT WAVE WITH SHORT CHOPPY PERIODS. NO SIGNIFICANT CHANGES ARE NEEDED TO THE FORECAST. PREVIOUS DISCUSSION FROM 730 PM FOLLOWS... THE COMBINATION OF BERMUDA HIGH PRESSURE WELL OFFSHORE AND A HEALTHY SEABREEZE CIRCULATION HAS PUSHED NEARSHORE WIND SPEEDS TO NEAR 20 KNOTS ALONG THE COAST OF THE CAROLINAS THIS EVENING. WIND SPEEDS WILL NOT DIE DOWN AS MUCH AS MARINERS MAY LIKE OVERNIGHT. AS SURFACE WINDS DIMINISH INLAND A SOUTHWESTERLY LOW-LEVEL JET WILL DEVELOP WITH 1000 FOOT WIND SPEEDS INCREASING TO A SOLID 20 KNOTS. THIS MOMENTUM WILL THEN MIX DOWN IN GUSTS OVERNIGHT ACROSS THE COASTAL WATERS...WITH WIND SPEEDS EXPECTED TO RANGE FROM 15-20 KNOTS. SEAS CURRENTLY CONSIST OF A SMALL 9-SECOND SOUTHEASTERLY SWELL AND PLENTY OF 5-SECOND WIND WAVES. THE WIND WAVES WILL BE THE DOMINANT WAVE SET OVERNIGHT...CURRENTLY 2-3 FEET AND MAY BUILD TO 4 FEET AWAY FROM SHORE LATE. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...PROBABLY GOING TO NEED SCEC EITHER LATE TUESDAY OR TUESDAY NIGHT. PRESSURE GRADIENT ACROSS THE AREA TIGHTENS IN RESPONSE TO DEVELOPING PIEDMONT TROUGH WHILE LARGE AREA OF HIGH PRESSURE SITS OVER THE WESTERN ATLANTIC. TOUGH CALL ON WEDNESDAY...MODELS SHOWING A SLIGHT DOWNWARD TREND IN WIND SPEED...OR AT LEAST LESS GUSTINESS. MEANWHILE SOME EASTERLY SWELL ENERGY IS PROGGED TO INCREASE. HAVE ADDED ABOUT A HALF A FOOT TO WHAT WNA GUIDANCE...INDICATING THAT WEDNESDAY MAY ALSO BE ON THE CUSP OF NEEDED SCEC HEADLINES. LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 3 PM MONDAY...SOUTHWEST FLOW WILL PERSIST THROUGH SAT WITH SUSTAINED WINDS 10 TO 15 KTS. NEARSHORE WINDS WILL BE A LITTLE HIGHER IN THE AFTERNOON/EVENING HOURS WITH SPEEDS ON THE LOWER END OF THE 15 TO 20 KT RANGE. SEAS 3 TO 4 FT AT THE START OF THE PERIOD WILL SUBSIDE TO 2 TO 3 FT FRI AND SAT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...SGL NEAR TERM...REK/TRA SHORT TERM...MBB LONG TERM...III AVIATION...BJR MARINE...REK/TRA/MBB

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