Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 240853 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 353 AM EST WED DEC 24 2014 .SYNOPSIS... LOW PRESSURE TO THE WEST OF THE APPALACHIANS WILL DEEPEN AND LIFT NORTH TOWARD THE GREAT LAKES PULLING A COASTAL FRONT FARTHER INLAND AND NORTH THROUGH TODAY. THIS LOW PRESSURE SYSTEM WILL DRAG A COLD FRONT THROUGH THE COASTAL CAROLINAS TONIGHT AS IT LIFTS OFF TO THE NORTHEAST. DRY HIGH PRESSURE WILL BUILD OVER THE SOUTHEAST CHRISTMAS DAY INTO FRIDAY BEFORE MOVING OFF THE COAST BY SATURDAY. A COLD FRONT WILL DROP INTO THE SOUTHEAST ON SUNDAY WITH A A FEW WAVES OF LOW PRESSURE DEVELOPING EARLY TO MID WEEK NEXT WEEK LEAVING UNSETTLED WEATHER ACROSS THE CAROLINAS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM WEDNESDAY...THE COASTAL FRONT/WARM FRONT THAT HAS SAT OFFSHORE FOR THE PAST FEW DAYS IS FINALLY PRESSING INLAND. THIS IS ALLOWING A TROPICAL AIRMASS INTO THE AREA WITH TEMPS AND DEWPOINTS ON THE WESTERN EDGE OF THE GULF STREAM NOW IN THE 70S. IN THE UPPER LEVELS A DEEP TROUGH JUST WEST OF THE MISSISSIPPI RIVER WILL MOVE INTO THE APPALACHIANS TONIGHT. EXCELLENT SYNOPTIC LIFT AIDED BY FLOW INTO THE RIGHT-ENTRANCE REGION OF A 140 KNOT 200 MB JET STREAK SHOULD BRING ANOTHER WAVE OF MODERATE TO HEAVY RAINFALL INTO THE AREA THIS MORNING THROUGH EARLY THIS AFTERNOON. EMBEDDED THUNDERSTORMS REMAIN POSSIBLE AS ELEVATED CAPE AROUND 500 J/KG (AND SURFACE-BASED CAPE OF 250-500 J/KG) IS EXPECTED TO DEVELOP LATER THIS MORNING. THE SEVERE WEATHER THREAT REMAINS LOW DUE TO LIMITED BOUNDARY LAYER INSTABILITY AND INCREASINGLY UNIDIRECTIONAL WINDS WITHIN THE LOWEST 3 KM. 850 MB TEMPS RISING TO +14C AND DEEP SOUTH FLOW WILL HELP PUSH TEMPERATURES IN THE 70S TODAY AWAY FROM THE BEACHES EVEN WITHOUT SIGNIFICANT INSOLATION. WHERE TEMPS CAN EXCEED 70 LOOK FOR ENOUGH MIXING TO DEVELOP TO TRANSPORT DOWN 35 MPH WIND GUSTS TO THE SURFACE. IF ENOUGH SUNSHINE COULD SOMEHOW DEVELOP TO PUSH TEMPERATURES INTO THE MID 70S (PRODUCING 2000 FEET OF VERTICAL MIXING) WIND GUSTS COULD CONCEIVABLY REACH 45 MPH! NEAR THE BEACHES WINDS OFF THE COLD OCEAN WILL ADVECT A SHALLOW VERY STABLE BOUNDARY LAYER ONSHORE WITH TEMPERATURES LIKELY STUCK IN THE UPPER 50S AND 60S ALL DAY. DENSE SEA FOG COULD ADVECT ONSHORE AS WELL...HOWEVER ENOUGH WIND SHOULD EXIST TO MIX THIS FOG UPWARD INTO A RAGGED STRATUS DECK BY NOON. PREFERRED MODELS TODAY INCLUDE THE 00Z NAM...00Z WRF-NMM...AND TO A LESSER EXTENT THE 00Z CANADIAN. A LULL IN PRECIPITATION IS EXPECTED DURING THE MID TO LATE AFTERNOON HOURS...WITH SHOWERS AND ISOLATED T-STORMS FIRING ALONG THE COAST THIS EVENING. THE ACTUAL SURFACE COLD FRONT SHOULD CROSS INTERSTATE 95 AROUND MIDNIGHT...POSSIBLY ACCOMPANIED BY ONE FINAL BAND OF SHOWERS. LOWS SHOULD RANGE FROM 50-55...WARMEST AT THE NC BEACHES. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM WEDNESDAY...A COLD FRONT WILL BE PUSHING FARTHER OFF SHORE THROUGH THURS AS HIGH PRESSURE BUILDS UP FROM GULF COAST. ANY LINGERING PCP OR MOISTURE WILL BE SCOURED OUT AS MID TO UPPER TROUGH MOVES EAST LEAVING A DEEP DRY AND COOLER W-NW FLOW BEHIND IT. EXPECT PCP WATER VALUES DOWN FROM UP NEAR 2 INCHES THE NIGHT BEFORE TO A QUARTER OF INCH BY THURS AFTERNOON AS COLUMN DRIES OUT. OVERALL EXPECT CLEARING SKIES ON CHRISTMAS DAY WITH SUNSHINE MAKING AN APPEARANCE FOR THE FIRST TIME IN SEVERAL DAYS. TEMPS SHOULD NOT MOVE MUCH ON THURS AS A WARM START TO THE DAY WILL BE FOLLOWED BY GUSTY W-NW WINDS BRINGING IN RELATIVELY COOLER AIR. MODELS HAVE BEEN CONSISTENTLY BACKING OFF ON CAA BEHIND THE FRONT WITH 850 TEMPS ONLY FALLING ABOUT 6 C BEHIND FRONT BEFORE LEVELING OFF AND RISING SLIGHTLY THROUGH FRI. TEMPS THURS NIGHT SHOULD BE DOWN IN THE 30S AND BASICALLY EXPECT SEASONABLE TO ABOVE NORMAL TEMPS IN THE FORECAST AS HIGH PRESSURE BUILDS UP FROM THE GULF COAST OVER THE SOUTHEAST THROUGH FRI. THE CENTER OF THE HIGH ALMOST DIRECTLY OVERHEAD FRI AFTN WILL SHIFT OFF SHORE BY FRI NIGHT LEAVING A LIGHT RETURN FLOW. THIS WILL HELP TO CAUSE A SLIGHT RISE IN DEWPOINT TEMPS AND THEREFORE WILL KEEP TEMP A BIT HIGHER THAN THE NIGHT BEFORE BUT THE WINDS WILL BE LIGHT ENOUGH UNDER CLEAR SKIES TO PRODUCE DECENT RADIATIONAL COOLING. THIS WILL BRING TEMPS DOWN CLOSER TO 40 FOR FRI NIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 330 AM WEDNESDAY...RIDGE OF HIGH PRESSURE UP THE SOUTHEAST COAST ON SATURDAY WILL SHIFT EAST THROUGH EARLY NEXT WEEK. THIS WILL ALLOW A RETURN FLOW TO SET UP WITH SW-W WINDS THROUGH THE LOW TO MID LEVELS OF THE ATMOSPHERE. INITIALLY SHOULD SEE A FAIR AMOUNT OF SUNSHINE ON SATURDAY BUT A COLD FRONT WILL DROP SOUTH ON SUNDAY LEAVING SHALLOW COOL AIR IN PLACE. SHOULD SEE CLOUDS AND PCP SPREAD OVER THE CAROLINAS SAT NIGHT INTO SUNDAY AS COLD FRONT DROPS SOUTH WITH SOME DECENT ISENTROPIC LIFT DEVELOPING. THE GFS AND ECMWF SHOW A FEW WAVES OF LOW PRESSURE MOVING UP FROM THE GULF COAST ALONG THIS FRONT THROUGH NEXT WEEK. MAY END UP WITH AN EXTENDED PERIOD OF UNSETTLED WEATHER AS POSSIBLE WEDGE SETS UP. TEMPS ON SAT INTO SUNDAY SHOULD REMAIN ON THE WARM SIDE WITH 60S MOST PLACES. SOME UNCERTAINTY EXISTS WITH LOCATION OF COLD FRONT AS ECMWF KEEPS IT NORTH AND SHOWS WAVES OF LOW PRESSURE MOVING ALONG FRONT TO THE NORTH OF LOCAL AREA. THIS COULD KEEP LOCAL AREA IN WARMER SW FLOW AT THE SURFACE WITH WEDGE HOLDING INLAND AND TO OUR NORTH. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 06Z...LATEST RADAR IMAGERY DEPICTS LIGHT SHRA ACROSS THE AREA. THIS ALONG WITH LOW CIGS AND FOG WILL CONTINUE TO CREATE FLUCTUATING PERIODS OF IFR/LIFR OVERNIGHT HOURS AHEAD OF A WARM FRONT WHICH WILL LIFT NORTHWARD THROUGH THE AREA OVER THE NEXT COUPLE OF HOURS. NORTHEASTERLY WINDS WILL SHIFT TO THE SOUTHEAST. MODELS SHOW INCREASING COVERAGE OF RAIN WITH EMBEDDED HEAVIER CONVECTIVE ELEMENTS 10-12Z INLAND AND 12-15Z AT THE COAST. DOWNPOURS AND ISOLATED THUNDERSTORMS MAY CONTINUE INTO THE AFTERNOON AND EVENING HOURS IN ASSOCIATION WITH AN APPROACHING COLD FRONT. GIVEN UNCERTAINTY OF TIMING OF HEAVIER DOWNPOURS OR TSRA...HAVE NOT INCLUDED IN GOING FORECAST. GENERALLY SOUTH WINDS WILL PICK UP...WITH SUSTAINED SPEEDS OF AROUND 10 TO 12 KTS AND GUSTS UP TO AROUND 20 KTS THIS AFTERNOON. WILL BEGIN TO SEE RAINFALL TAPER OFF AS THE COLD FRONT PUSHES THROUGH TONIGHT. EXTENDED OUTLOOK...PRECIP ENDING NEAR THE COAST LATE TONIGHT WITH THE COLD FRONT PUSHING TO THE COAST THURSDAY MORNING WITH GUSTY WEST WINDS. VFR FRIDAY AND SATURDAY. RAIN RETURNING SUNDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM WEDNESDAY...THE COASTAL FRONT/WARM FRONT HAS FINALLY PUSHED ONSHORE WITH SOUTHEASTERLY WINDS SHOWING UP AT MOST BEACHES AND BUOYS. THE AIRMASS PUSHING ONSHORE IS TROPICAL WITH DEWPOINTS AROUND 70 AND AIR TEMPERATURES IN THE MID 70S COMING OFF THE GULF STREAM. WITH NEARSHORE OCEAN WATER TEMPERATURES IN THE LOWER TO MIDDLE 50S...SIGNIFICANT COOLING OF THE THIN BOUNDARY LAYER WILL RESULT IN DENSE SEA FOG LASTING MOST OF THE DAY. FOG COULD CONTINUE INTO THIS EVENING BUT SHOULD END COMPLETELY AFTER MIDNIGHT AS WINDS VEER WESTERLY WITH AN APPROACHING COLD FRONT AND MUCH DRIER AIR ADVECTS OFFSHORE. WE ARE CURRENTLY IN A LULL WITH SHOWER ACTIVITY...HOWEVER UPSTREAM RADARS AND MODEL DATA INDICATE SHOWERS AND EMBEDDED THUNDERSTORMS SHOULD REDEVELOP ACROSS THE AREA THIS MORNING. ACTIVITY MAY TAPER OFF AGAIN DURING THE MID TO LATE AFTERNOON HOURS...WITH A SECOND WAVE OF SHOWERS AND STORMS EXPECTED THIS EVENING. THE ACTUAL COLD FRONT ITSELF WILL PUSH ACROSS THE WATERS SHORTLY AFTER MIDNIGHT... PERHAPS ACCOMPANIED BY ONE FINAL LINE OF SHOWERS. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM WEDNESDAY...COLD FRONT WILL SHIFT FARTHER OFF SHORE ON THURS AS HIGH PRESSURE BUILDS UP FROM THE GULF COAST. GUSTY W-SW WINDS EARLY THURS WILL VEER AROUND BECOMING WEST THROUGH THE DAY. SEAS UP AROUND 5 TO 7 FT SHOULD FALL BELOW SCA THRESHOLDS BY THURS AFTN WITH HIGHEST SEAS GETTING PUSHED FARTHER OFF SHORE IN STRONGER W-NW FLOW BEHIND FRONT. WINDS WILL VEER FURTHER TO THE NW AND LIGHTEN UP LATE THURS INTO FRI AS CENTER OF HIGH SHIFTS CLOSER OVERHEAD. SEAS WILL BE DOWN TO 2 TO 4 FT BY THURS NIGHT AND DOWN TO 3 FT OR LESS THROUGH FRI AS HIGH PRESSURE MOVES OVERHEAD WITH MORE VARIABLE WINDS EXPECTED. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 330 AM WEDNESDAY...HIGH PRESSURE WILL SHIFT FARTHER OFF SHORE ON SATURDAY WITH A RETURN FLOW S-SW 10 KTS OR LESS SETTING UP. A COLD FRONT WILL DROP SOUTH SUN WITH POSSIBLE WEDGE DEVELOPING WITH WINDS VEERING AROUND TO THE N-NE AS IT DROPS SOUTH SUN NIGHT. THIS WILL PUSH SEAS UP A BIT BUT OVERALL BUT EXPECT SEAS TO GENERALLY 3 FT OR LESS THROUGH THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...DENSE FOG ADVISORY UNTIL 6 PM EST THIS EVENING FOR AMZ250-252- 254-256. SMALL CRAFT ADVISORY UNTIL NOON EST THURSDAY FOR AMZ250-252- 254-256. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RGZ AVIATION...TRA/SGL

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