Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 261918 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 318 PM EDT TUE APR 26 2016 .SYNOPSIS... WARM WEATHER IS EXPECTED THROUGH FRIDAY. A COLD FRONT WILL BRING SHOWERS THURSDAY INTO THURSDAY NIGHT. HIGH PRESSURE WILL BUILD IN ON SATURDAY BRINGING A BIT OF A COOL DOWN. RAIN CHANCES RAMP UP ON SUNDAY AND WILL PERSIST FOR THE FEW DAYS THAT FOLLOW. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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AS OF 315 PM TUESDAY...LARGE HIGH PRESSURE OFFSHORE CONTINUES TO BE THE CONTROLLING INFLUENCE ON THE SENSIBLE WEATHER TODAY. A SECOND DAY OF MOIST RETURN FLOW HAS ALLOWED COLUMN PWATS TO INCREASE...AND WITHOUT LOOKING AT SOUNDINGS THIS IS EVIDENT FROM THE MUCH MORE WIDESPREAD CUMULUS ACROSS THE AREA THIS AFTN. THE HIGH RES GUIDANCE WAS DEPICTING SCATTERED SHOWERS TODAY...AND CU HAS BECOME AGITATED ENOUGH ALONG THE PIEDMONT TROUGH THAT A SPOT SHOWER OR TWO HAS DEVELOPED AND MAY CONTINUE INTO THIS EVENING BEFORE WANING QUICKLY WITH LOSS OF HEATING. CONTINUED DRY AIR ALOFT HOWEVER HAS PREVENTED OTHER SHOWER DEVELOPMENT...EVEN ALONG A ROBUST SEA BREEZE. CUMULUS WILL ERODE QUICKLY AFTER DARK LEAVING A MOSTLY CLEAR NIGHT...ALTHOUGH SOME MID/HIGH LEVEL CLOUDINESS MAY SPREAD FROM THE NORTH LATE...AND SOME INCREASED MOISTURE IN THE FORM OF STRATOCUMULUS MAY DEVELOP WITHIN THE LLJ OVERNIGHT. THIS LLJ IS FORECAST TO BE QUITE STRONG...30-35 MPH AROUND 1500 FT...AND THIS WILL PREVENT SHARP STEEPENING OF THE NOCTURNAL INVERSION OVERNIGHT. CONTINUED WARM SW SURFACE WINDS AND A WEAK INVERSION WILL KEEP MINS ELEVATED OVERNIGHT...AND HAVE SIDED WITH THE WARMER EDGE OF GUIDANCE...62-66 ACROSS THE AREA.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
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AS OF 315 PM TUESDAY...WARM AND HUMID CONDITIONS TO CONTINUE THIS PERIOD AS BERMUDA HIGH PRESSURE PERSISTS OFFSHORE. AT THE SAME TIME...A COLD FRONT WILL BE SLOWLY DROPPING SOUTH...AND THESE FEATURES COMBINES WILL CREATE INCREASING CHANCES FOR TSTMS. EXPANSIVE AREA OF HIGH PRESSURE OFFSHORE WILL CONTINUE TO RIDGE BACK INTO THE CAROLINAS WEDNESDAY AND THURSDAY...ONLY BECOMING SLOWLY DISPLACED BY A COLD FRONT THURSDAY NIGHT. RETURN FLOW AROUND THIS HIGH WILL DRIVE INCREASING WARMTH AND HUMIDITY...BUT THIS WILL COME WITH THE COST OF PROMOTING BETTER CONVECTION CHANCES EACH DAY. ON WEDNESDAY...HIGHS WILL SOAR INTO THE MID AND EVEN UPPER 80S AWAY FROM THE COAST...WHILE A SEA BREEZE WILL KEEP THE BEACH COMMUNITIES 5- 10 DEGREES COOLER. THE COMBINATION OF THESE WARM TEMPS AND DEWPOINT VALUES IN THE 60S WILL CREATE AMPLE INSTABILITY...FORECAST TO BE AROUND 1500 J/KG...AND AIR MASS TYPE PULSE CONVECTION IS POSSIBLE WEDNESDAY. THE SEA BREEZE AND PIEDMONT TROUGH WILL LIKELY SERVE AS THE INITIAL FOCUS FOR STORMS...BUT ANY BOUNDARIES COULD DRIVE STORMS ON WEDNESDAY. FORECAST SOUNDINGS REMAIN PRETTY DRY ABOVE 700 MB...SO DO NOT EXPECT WIDESPREAD OR STRONG STORMS...BUT AT LEAST SCATTERED COVERAGE IS LIKELY. MOST OF THIS ACTIVITY WILL WANE AFTER DARK AS IT IS PRIMARILY DIURNALLY FORCED...BUT A WARM NIGHT WILL REMAIN AS LOWS FALL ONLY INTO THE MID 60S. A SIMILAR DAY FORECAST FOR THURSDAY...BUT MORE WIDESPREAD CONVECTION IS FORECAST AS THE AFOREMENTIONED FRONT DROPS FURTHER SOUTH AND MID- LEVEL HEIGHTS DROP LEADING TO STEEPER LAPSE RATES. TEMPS ONCE AGAIN IN THE LOW/MID 80S WILL CREATE AMPLE INSTABILITY OF 1500-200 J/KG WHICH WILL FUEL STORMS ON THURSDAY. THE TYPICAL BOUNDARIES WILL AGAIN BE FAVORED DURING THE AFTN...BUT AS THE FRONT DROPS SLOWLY INTO THE AREA THURSDAY EVE AND NIGHT...CONVECTION COULD BECOME MORE WIDESPREAD AND LAST WELL AFTER DARK. SPC HAS THE AREA IN A MARGINAL RISK FOR THE SWODY3...BUT OTHER THAN LARGE CAPE VALUES THE OVERALL SEVERE PARAMETERS ARE LOW...AND ATTM DO NOT EXPECT MUCH SEVERE POTENTIAL...BUT AN ISOLATED WET MICROBURST IS POSSIBLE THANKS TO A SUBTLE INVERTED-V IN THE INCREASINGLY SATURATED ENVIRONMENT. COLD FRONT WILL BE MOVING OFFSHORE AT THE END OF THE PERIOD...BUT LOWS WILL AGAIN REMAIN WARM...FALLING ONLY INTO THE MID 60S...LOW 60S WELL NORTH.
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&& .LONG TERM /FRIDAY THROUGH TUESDAY/...
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AS OF 315 PM TUESDAY...THE MID LEVEL PATTERN WILL CONTINUE TO BE HIGHLY AMPLIFIED AND SLOW MOVING...NOT SURPRISING FOR LATE APRIL IN THE TRANSITION SEASON FROM SPRING TO SUMMER. LOW PRESSURE WILL BE LOCATED OVER THE SOUTHWEST WITH A ZONAL FLOW TO THE EAST. THE FLOW SLOWLY BECOMES SOUTHWEST ACROSS OUR AREA BY TUESDAY AS THE LOW OPENS UP AND MEANDERS EAST. AS FOR THE SURFACE FEATURES...HIGH PRESSURE BUILDING IN FROM THE NORTHEAST SHOULD KEEP FRIDAY AND SATURDAY DRY. BY SUNDAY HIGHER THETA-E AIR ARRIVES AND WITH MINIMAL FORCING...SEA BREEZE AND THE PIEDMONT TROUGH IT IS ENOUGH TO WARRANT SLIGHT CHANCE POPS. BETTER MID LEVEL FORCING ALONG WITH THE PREVIOUS ELEMENTS WARRANT HIGHER POPS MONDAY. SOME UNCERTAINTY FOR TUESDAY AS THE GFS IS MORE PROGRESSIVE IN CLEARING THING OUT WHILE THE ECMWF MOVES ANOTHER SYSTEM ACROSS. MAINTAINED SHOWERS IN THE FORECAST FOR NOW BUT THIS IS SUBJECT TO CHANGE. TEMPERATURES SHOULD BE ABOVE NORMAL MOST OF THE PERIOD. WARMEST FRIDAY BEFORE THE HIGH BUILDS IN AND THE MOISTURE RETURNS.
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&& .AVIATION /19Z TUESDAY THROUGH SUNDAY/... AS OF 18Z...EXPECT VFR CONDITIONS THRUOUT THE VALID 24 HR 18Z ISSUANCE PERIOD. WINDS REMAIN THE PROBLEM CHILD FOR THIS FCST. LIMITED MOISTURE AND FORCING FROM AN INLAND PROGRESSING AND POTENT SEA BREEZE THAT WILL YIELD FEW/SCT DIURNALLY DRIVEN CU THRU THIS AFTN AND EARLY EVENING. BEHIND THE SEA BREEZE...STABLE LOW LEVEL MARINE AIR WILL KEEP SKIES SKC. SUBSIDENCE ALOFT WILL LIMIT THE VERTICAL GROWTH OF THE CU...WITH THEIR TOPS BEING FLATTENED OUT. THUS COULD OBSERVE MODERATE CU GROWTH AT BEST...WITH NO PCPN EXPECTED. FOR TONIGHT...DIURNALLY DRIVEN CU WILL DISSIPATE THIS EVENING. DO NOT EXPECT ANY FOG DEVELOPMENT DUE TO SFC WINDS STAYING ACTIVE. AS FOR WINDS...THE CENTER OF HIGH PRESSURE WILL PUSH FURTHER OFFSHORE FROM THE CAROLINA COASTS THRU THIS PERIOD...WITH ITS SFC RIDGE AXIS EXTENDING WESTWARD AND ONSHORE NEAR THE GA-SC STATE LINE. A SLOW TIGHTENING OF THE SFC PG WILL ALSO BE PRESENT INTO WED. IN ADDITION...AN ACTIVE AND POTENT INLAND PROGRESSING SEA BREEZE THIS AFTN...WILL REACH THE FLO AND LBT LINE AROUND SUNSET. OVERALL...LOOKING AT SW-WSW WINDS AT 10 KT G15 KT...BACKING TO S-SSW AT 10-15 KT WITH G17-19 KT. THE COASTAL TERMINALS WILL SEE S-SSW AROUND 15 KT G20-25 KT INTO THIS EVENING. ALL LOCATIONS WILL SEE WINDS BACK TO SW-WSW AT 5 TO 10 KT BY MIDNIGHT AND LIKELY HOLD AT THIS SPEEDS OVERNIGHT. THE LATTER DUE TO A DEVELOPING LOW-LEVEL JET FROM THE SW AT 30-35 KT AT 1100 TO 1400 FT AGL. AS A RESULT... COULD SEE WIND GUSTS UP TO 15 KT ESPECIALLY AT THE COASTAL TERMINALS AFTER MIDNIGHT. THE SFC PG RELAXES-SOME BY WED DAYTIME MORNING...YIELDING WSW WINDS AT 5 TO 10 KT. THE WED SEA BREEZE WILL DEVELOP BY NOON. EXTENDED OUTLOOK...ISOLATED CONVECTION POSSIBLE WED AFTERNOON AND EVENING. INCREASED CHANCES FOR SCATTERED CONVECTION THURSDAY INTO FRIDAY DUE TO A BACK-DOOR COLD FRONT DROPPING SOUTHWARD. OTHERWISE EXPECT VFR. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 315 PM TUESDAY...HIGH PRESSURE OFFSHORE WILL MAINTAIN ITS INFLUENCE ACROSS THE WATERS THROUGH TONIGHT. SW WINDS AROUND THE HIGH PRESSURE HAVE BEEN AROUND 15 KTS...AND THESE ARE EXPECTED TO PERSIST WITH LITTLE FLUCTUATION THROUGH THE REMAINDER OF THE NEAR TERM. HOWEVER...SEA BREEZE WINDS IN THE NEAR SHORE WATERS HAVE BEEN GUSTING TO 20 KTS...AND THESE WILL SLOWLY EASE TO JOIN THE SYNOPTIC WINDS THIS EVENING. SEAS AROUND 2-3 FT WILL BUILD AT TIMES TO 3-4 FT ESPECIALLY NEAR THE 20 NM BOUNDARY...WITH AN E SWELL AND LOCAL SHORT PERIOD WIND CHOP. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 315 PM TUESDAY...LARGE HIGH PRESSURE OFFSHORE WILL BE THE DOMINANT INFLUENCE ON THE WATERS THIS PERIOD AS IT DRIFTS VERY SLOWLY TO THE EAST. THIS WILL DRIVE PERSISTENT SW WINDS OF AROUND 15 KTS...INCREASING TO 20 KTS AT TIMES THROUGH THURSDAY NIGHT...AS A COLD FRONT APPROACHING FROM THE NORTH PINCHES THE GRADIENT. THIS FRONT WILL BE ALONG OR JUST NORTH OF THE NORTHERN EDGE OF THE WATERS THURSDAY NIGHT WITH THE ASSOCIATED WIND SHIFT TO THE NW EXPECTED BEYOND THE SHORT TERM. SEAS WILL BE 3-4 FT MUCH OF THE PERIOD WITH A 9-10 SEC SE SWELL AND 5 SEC SW WIND WAVE PRODUCING THE SPECTRUM. LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 315 PM TUESDAY...OVERALL SOMEWHAT MANAGEABLE CONDITIONS FOR THE MARINE COMMUNITY FOR THE EXTENDED ALTHOUGH NOT IDEAL. A BRIEF WESTERLY FLOW WILL BE IN PLACE INITIALLY WITH LIGHT AND VARIABLE WINDS LATER FRIDAY INTO SATURDAY MORNING. A BETTER DEFINED NORTHEAST FLOW DEVELOPS LATER SATURDAY IN A 10-15 KNOT RANGE. BY LATER SUNDAY AN ONSHORE FLOW WILL DEVELOP. THE HIGHEST WIND SPEEDS SHOULD OCCUR EARLY FRIDAY AROUND 15 KNOTS. THE SEAS WILL BE MANAGEABLE THROUGHOUT WITH THE LIGHT WIND FIELDS. EXPECT A MOSTLY 2-4 FOOT RANGE WITH IF ANYTHING EVEN LOWER VALUES.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...SHK NEAR TERM...JDW SHORT TERM...JDW LONG TERM...SHK AVIATION...DCH

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