Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 182327 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 627 PM EST TUE NOV 18 2014 .SYNOPSIS... ARCTIC HIGH PRESSURE WILL BRING RECORD COLD TEMPERATURES AND DRY AIR TONIGHT. TEMPERATURES WILL MODERATE THURSDAY AND FRIDAY AS ANOTHER AREA OF HIGH PRESSURE BUILDS INTO THE AREA. THIS HIGH WILL MOVE OFF THE COAST SATURDAY WITH A WARM AND MOIST RETURN FLOW BRINGING INCREASING RAIN CHANCES SUNDAY AND MONDAY. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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AS OF 6:30 PM TUESDAY...CLEAR SKIES AND PLUMMETING TEMPERATURES THIS EVENING WITH TEMPERATURES ALREADY BELOW FREEZING OVER SOME OF OUR INLAND LOCALES. FORECAST COVERS THIS WELL...PREVIOUS DISCUSSION FOLLOWS: DISCUSSION TODAY REVOLVES AROUND THE VERY COLD TEMPERATURES AS WELL AS SOME HIGH LEVEL CLOUDINESS. OTHERWISE...LITTLE TO MENTION IN TERMS OF SENSIBLE WEATHER DURING THE NEAR TERM. ARCTIC HIGH PRESSURE IS SETTLING ACROSS THE SOUTHEAST...WITH THE CENTER OF THIS HIGH PUSHING EASTWARD THIS EVENING. AS THIS HIGH PRESSURE ADVANCES...COLD ADVECTION WILL CONTINUE BENEATH 850MB ON COOL N/NW WINDS...SHUTTING OFF ONLY VERY LATE TONIGHT AND TOWARDS WEDNESDAY MORNING. HIGH TEMPERATURES HAVE STRUGGLED ONLY INTO THE LOW 40S...WITH A FEW MID 40S ALONG THE CAPE FEAR COAST. THE COOLEST TEMPS HAVE BEEN INLAND WHERE SOME HIGH LEVEL CIRRUS HAS BEEN PLAGUING THE AREA. THIS CIRRUS IS DUE TO A WEAK JET-LEVEL IMPULSE AND SOME INCREASED RH ABOVE 400MB. A COWORKER HERE RECENTLY NOTICED THAT THE CIRRUS HAS TAKEN ON A MORE CIRRO-CU APPEARANCE...WHICH JIVES WELL WITH SOME VERY...VERY...ELEVATED INSTABILITY WHERE LAPSE RATES BETWEEN 400MB AND 250MB ARE NEAR MOIST-ADIABATIC LEVELS. WHILE THIS WILL HAVE NO SENSIBLE WEATHER IMPACTS...PARTLY...TO AT-TIMES POTENTIALLY MOSTLY CLOUDY CONDITIONS WILL EXIST BEFORE THIS IMPULSE RACES TO THE NE AND DRYING OCCURS WITHIN THE JET LAYER. THEREAFTER...THE BIGGEST CONCERN IS THE SIGNIFICANT COLD EXPECTED TONIGHT. LATEST GUIDANCE HAS COME UP A BIT WITH MIN TEMPS...AND IT MAY NOT FULLY DECOUPLE LOCALLY THANKS TO PERSISTENT LOW-LEVEL CAA. FOR THIS REASON HAVE BUMPED MINS A BIT AREA-WIDE...AND AM NO LONGER EXPECTING ANY TEMPERATURES BELOW 20 EXCEPT IN THE ISOLATED NORMALLY COLD AREAS. STILL LOOKING AT RECORD COLD HOWEVER: WILMINGTON 25 SET IN 1959 CURRENT FORECAST IS 23 FLORENCE 24 SET IN 1951 CURRENT FORECAST IS 20 N MYRTLE BEACH 25 SET IN 1949 CURRENT FORECAST IS 24 IF ANY LOCATION DOES DROP BELOW 20 TONIGHT...IT WILL BE THE FIRST TIME IN THIS AREA SINCE THE END OF JANUARY WE HAVE EXPERIENCED TEENS FOR TEMPERATURES.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... AS OF 300 PM TUESDAY...1030 MB ARCTIC HIGH PRESSURE WILL BE CENTERED OVER THE AREA WEDNESDAY MORNING. MODEST NOVEMBER SUNSHINE AND WEAK WARM ADVECTION ON WESTERLY MID-LEVEL WINDS WILL WARM TEMPS ONLY TO 45-50...ABOUT 20 DEGREES BELOW NORMAL. THE AIRMASS WILL BE EXCEPTIONALLY DRY WITH PRECIPITABLE WATER VALUES FORECAST TO BOTTOM OUT AROUND 0.1 INCHES...NEARLY AS LOW AS IT CAN PHYSICALLY GET THIS IN PART OF THE WORLD. THIS WILL TRANSLATE TO LOW RELATIVE HUMIDITY (20-25 PERCENT) WEDNESDAY AFTERNOON. IN RESPONSE TO PERSISTENT UPPER LEVEL TROUGHING ACROSS THE NORTHEASTERN QUARTER OF THE NATION AND SOUTHERN STREAM RIDGING ACROSS THE DESERT SOUTHWEST AND TEXAS...THE ARCTIC HIGH AT THE SURFACE WILL SHIFT SOUTH WEDNESDAY NIGHT RATHER THAN EAST OFF THE COAST AS IS MORE TYPICAL. A BELT OF MODERATE WESTERLY WINDS WILL DEVELOP NORTH OF THE HIGH...ADDING A BIT OF A QUESTION TO HOW WELL-ESTABLISHED THE RADIATION INVERSION WILL BECOME. TOO MUCH WIND CAN PERTURB THE BOUNDARY LAYER DEPTH AND KEEP NIGHTTIME SURFACE TEMPS WARMER THAN WOULD OTHERWISE OCCUR. MY FORECAST LOWS ARE ON THE HIGH SIDE OF MOS GUIDANCE ESPECIALLY ACROSS SE NORTH CAROLINA. ON THURSDAY THE DECAYING ARCTIC HIGH TO OUR SOUTH WILL BRIDGE ACROSS WITH A NEW HIGH DROPPING SOUTHEASTWARD FROM THE PLAINS STATES. WESTERLY MID-LEVEL FLOW SHOULD CONTINUE THE MODEST WARM ADVECTION. WITH 850 MB TEMPS ANTICIPATED TO REACH +5C THURSDAY HIGHS SHOULD 55-60...STILL WELL BELOW NORMAL. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 300 PM TUESDAY...THE BIG STORY FOR THE EXTENDED FORECAST WILL BE THE WARMUP FOR THE WEEKEND EXTENDING INTO EARLY NEXT WEEK. THE MID LEVEL PATTERN WILL BECOME ORIENTED FROM THE SOUTHWEST WHICH IS A WARMING SETUP FOR OUR AREA AS A MID LEVEL CLOSED LOW DEVELOPS OVER THE FOUR CORNERS REGION. THIS SYSTEM WILL MOVE SLOWLY TO THE NORTHEAST AND SHEAR OUT BY EARLY MONDAY. DURING THIS PROCESS THE FLOW BECOMES ALMOST DUE SOUTH TO NORTH WHICH ADVECTS MUCH WARMER AND MOISTURE LADEN AIR INTO THE CWA. THESE ELEMENTS WILL BE MOST PRONOUNCED SUNDAY WHEN 850MB TEMPERATURES RISE TO ALMOST 13 DEGREES C. PRECIPITABLE WATER VALUES INCREASE TO ALMOST TWO INCHES WITH A NICE THETA E AXIS. WITH THIS MOISTURE AND BROAD UPPER LEVEL SUPPORT...WE HAVE LIKELY POPS IN THE FORECAST. THE TRAILING FRONT WILL NOT MOVE ACROSS UNTIL TUESDAY WHEN ANOTHER SHORTWAVE FINALLY DRIVES IT OUT. MONDAY AND TUESDAY FOR THAT MATTER COULD REMAIN UNSETTLED WITH AMPLE MOISTURE HANGING AROUND WITH THE SOUTHWEST FLOW. TEMPERATURES WILL INITIALLY BE SLOW TO INCREASE AS A WEDGE SCENARIO PREVAILS FOR FRIDAY AND SATURDAY. HIGHS WILL BE IN THE 50S FRIDAY...A LITTLE WARMER INTO THE LOWER 60S SATURDAY AND THE 70S SUNDAY AND MONDAY. TUESDAY WILL LIKELY SEE LOWER HIGHS AS THE FRONT MOVES ACROSS. OVERNIGHT LOWS WILL FOLLOW A SIMILAR TREND...COLD INITIALLY RISING TO ABOVE CLIMATOLOGY BY SUNDAY. && .AVIATION /23Z TUESDAY THROUGH SUNDAY/... AS OF 00Z...HIGH CONFIDENCE FOR VFR CONDITIONS THROUGH THE FORECAST PERIOD. HIGH PRESSURE WILL DOMINATE THE WEATHER WITH STRONG SUBSIDENCE EXPECTED. A SMALL JET STREAK IS MOVING OUT OF THE REGION WITH CLEARING SKIES. A MODERATE RADIATION INVERSION WILL SET UP...ALLOWING TEMPS TO DROP INTO THE LOW 20S IN SPOTS...POSSIBLY TEENS IN THE USUAL COLD SPOTS. WINDS WILL BE RATHER VARIABLE ON WEDNESDAY...WITH HIGH PRESSURE DIRECTLY OVERHEAD. THE COASTAL TERMINALS MAY EVEN GET A BIT OF A RESULTANT LATE IN THE AFTERNOON. EXTENDED OUTLOOK...VFR. LOW CONFIDENCE OF MVFR CIGS SATURDAY. MVFR CIGS MORE LIKELY SUNDAY WITH SHOWERS/ISOLATED THUNDERSTORMS && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 630 PM TUESDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: ARCTIC HIGH PRESSURE BUILDING EAST HAS KEPT THE GRADIENT SOMEWHAT PINCHED ACROSS THE COASTAL WATERS...BUT A SLOW WEAKENING TREND IS BEING OBSERVED. NW WINDS HAVE EASED TO AROUND 15 KTS...AND THIS MORNINGS SMALL CRAFT ADVISORY EXPIRED ON TIME AT 1PM. AS THE HIGH CONTINUES TO PUSH EAST TONIGHT...THE GRADIENT WILL CONTINUE TO SLACKEN...AND WINDS ARE EXPECTED TO FALL TO AROUND 10 KTS WHILE VEERING SLIGHTLY MORE TO THE NORTH. THESE LIGHTER WINDS WILL CONTINUE TO ALLOW WAVE HEIGHTS TO FALL...FROM THE CURRENT 2-4 FT TO 1-3 FT BY WEDNESDAY MORNING. NEAR SHORE SEAS WILL REMAIN JUST AROUND 1 FT. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 300 PM TUESDAY...ARCTIC HIGH PRESSURE OVER THE INLAND CAROLINAS WEDNESDAY WILL MAINTAIN A NORTH WIND ACROSS THE WATERS WEDNESDAY. AS THE RIDGE AXIS SETTLES SOUTH OF THE AREA WINDS WILL BECOME SOUTHWESTERLY DURING THE LATE AFTERNOON AND EVENING... INCREASING TO W 15 KNOTS WEDNESDAY NIGHT. WESTERLY WINDS WILL CONTINUE INTO WEDNESDAY NIGHT...SHIFTING NORTHERLY LATE AS A NEW HIGH APPROACHES FROM THE NORTHWEST. SEAS WILL CONSIST MAINLY OF SHORTER PERIOD WIND WAVES...RISING AND FALLING IN RESPONSE TO LOCAL WINDS. THE HIGHEST SEAS (3-4 FEET) ARE EXPECTED AWAY FROM SHORE THURSDAY IN THE STRONGER WESTERLY WINDS. LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 300 PM TUESDAY...WINDS WILL MAINTAIN A NORTHERLY COMPONENT FRIDAY AND EARLY SATURDAY AS HIGH PRESSURE MOVES FROM THE APPALACHIANS TO THE MID ATLANTIC REGION. SPEEDS WILL GENERALLY BE LIGHT WITH HIGHEST VALUES EARLY...10-15 KNOTS DROPPING TO TEN KNOTS OR LESS BY SATURDAY AM. BY SATURDAY AFTERNOON THE FLOW WILL TURN EAST THEN SOUTHEAST BY SUNDAY MORNING AND INCREASE TO 15-20 KNOTS AS A POTENT STORM SYSTEM...WELL TO THE WEST INCREASES THE GRADIENT. WINDS INCREASE FURTHER BY SUNDAY AFTERNOON TO 20-25 KNOTS. SEAS WILL FOLLOW THE SAME TRENDS...1-3 FEET FRIDAY INCREASING TO WELL OVER THE SIX FOOT SMALL CRAFT CRITERIA SUNDAY.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...REK/JDW SHORT TERM...TRA LONG TERM...SHK AVIATION...DL MARINE...REK/TRA/JDW/SHK

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