Area Forecast Discussion
Issued by NWS Wilmington, NC

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037 FXUS62 KILM 101421 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 921 AM EST WED FEB 10 2016 .SYNOPSIS... A DRY ARCTIC FRONT WILL REINFORCE THE COLD AIR TODAY. BELOW NORMAL TEMPERATURES ARE EXPECTED TODAY AND THROUGH THE REST OF THE WEEK. ANOTHER ARCTIC FRONT WILL CROSS THE AREA FRIDAY WITH A SMALL CHANCE FOR SOME SHOWERS. EVEN COLDER AIR WILL FOLLOW AND THE COLDEST AIR OF THE SEASON IS FORECAST THIS WEEKEND. TEMPERATURES WILL BEGIN TO MODERATE EARLY NEXT WEEK AS THE CENTER OF THE ARCTIC HIGH MODIFIES AND MOVES AWAY FROM THE REGION. A LOW PRESSURE SYSTEM MAY IMPACT THE AREA ON TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 930 AM WEDNESDAY...ONLY A COUPLE OF MINOR TWEAKS TO THE CLOUD COVER AND HOURLY TEMPERATURE GRIDS THIS MORNING. OTHERWISE FORECAST IS ON TRACK WITH A COLD AND BREEZY DAY. PREVIOUS DISCUSSION FOLLOWS: A LARGE AMPLITUDE UPPER TROF WILL BE THE MAIN PLAYER ALOFT FOR THE ILM CWA AS WELL AS ROUGHLY THE EASTERN 1/2 OF THE UNITED STATES. THIS WILL RESULT IN A CONTINUED ROUGHLY 15 DEGREE BELOW NORMAL TEMPERATURE REGIME DURING THIS PERIOD. FOR TODAYS HIGHS...WENT WITH A 40 TO 45 DEGREE RANGE AND THIS MAY BE TOO MILD GIVEN TEMPERATURES AT 850MB ARE PROGGED TO DROP TO -10 TO -13 DEGREES C BY THIS EVENING. ENOUGH MOISTURE IN THE LOWER LEVELS AND THE DYNAMICS FROM THE SHEARED VORT OVERHEAD...MAY BE ENOUGH TO PRODUCE SCATTERED...TO POSSIBLY A BROKEN DECK OF STRATOCU CLOUDS OVER NORTHERN PORTIONS OF THE ILM CWA WHERE SKIES WILL BE PARTLY CLOUDY. FOR TONIGHT...850MB TEMPS ACTUALLY WARM TO -6 TO -9 DEGREES C BY DAYBREAK THU. THIS IS IN RESPONSE TO A TRANSITION TO A SLIGHTLY LOWER AMPLIFICATION TO THE LONGWAVE UPPER TROF ACROSS THE FA...AND A NORTHWARD PLACEMENT/ADJUSTMENT OF THE LINE OF SHEARED VORTICITY IN THE MID-LEVELS. AT THE SFC...THIS WILL RESULT IN A RELAXING SFC PG DURING TONIGHT. AND WITH THE CAA BECOMING NEUTRAL AT THE SFC...NO GUSTY WINDS ARE EXPECTED. THE WAA ALOFT WILL NOT BE REALIZED AT THE SFC TONIGHT...AND AS A RESULT HAVE STAYED WITH THE COLDEST OF THE AVBL MODEL MOS GUIDANCE...WHICH IS IN THE LOW 20S WITH POSSIBLE OUTLIER UPPER TEENS WEST OF THE I-95 CORRIDOR. SFC DEWPOINTS ARE PROGGED TO DROP INTO THE TEENS LATER TODAY AND CONTINUE THRU TONIGHT. THIS IS TYPICAL OF A DRY ARCTIC AIRMASS. THE INFLUX OR ADVECTION OF THIS COLD DRY AIR MASS WILL BE DELIVERED BY WEST TO NW WINDS AT 10 TO 20 MPH...WITH OCCASIONAL GUSTS UP TO 25+ MPH DURING DAYLIGHT HOURS TODAY WHERE MIXING IN THE LOW LEVELS WILL BE ABLE TO PULL DOWN THOSE HIER WINDS ALOFT. WIND CHILL READINGS FORA COUPLE HOURS THIS MORNING WILL RANGE FROM THE UPPER TEENS INLAND...IE. IN THE VICINITY OF THE I-95 CORRIDOR...TO THE LOW 20S AT THE COAST. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM WEDNESDAY...WELL BELOW NORMAL TEMPERATURES TO RULE THE SHORT TERM AS A LARGE UPPER TROUGH DOMINATES THE EASTERN CONUS. WITHIN THIS TROUGH...A PIECE OF VORT ENERGY WILL ROTATE THROUGH THE CAROLINAS LATE FRIDAY...WITH SOME INCREASING CLOUDINESS AND MAYBE SOME PRECIP BENEATH IT. THE ANTECEDENT COLUMN IS QUITE DRY...PWATS AROUND 0.25 INCHES THURSDAY INTO FRIDAY...SO AS THE IMPULSE MOVES OVERHEAD PRECIP WILL BE TOUGH TO DEVELOP. SOUNDINGS DO SUGGEST SATURATION BOTH ABOVE 600MB AND BELOW 800MB...BUT THE DENDRITIC ZONE REMAINS VERY DRY. THIS COULD BE A SITUATION WHERE SNOWFLAKES WILL EVAPORATE INTO THE DENDRITIC ZONE ALOFT...LEAVING JUST A FEW COLD SPRINKLES/SHOWERS LOCALLY. HOWEVER...CANNOT RULE OUT A FEW SNOWFLAKES IF THE VORT BECOMES MORE POTENT AND CAN SATURATE THE ENTIRE COLUMN BEFORE TEMPS WARM NEAR THE SURFACE...BUT ATTM LOCAL TOPDOWN METHODOLOGY PRODUCES ALL LIQUID AND WILL CARRY JUST -RW WITH VERY LIGHT QPF. THE PRIMARY STORY THEN IS THE BELOW NORMAL TEMPS...FORECAST TO BE 10- 15 DEGREES BELOW CLIMO FOR EARLY FEBRUARY. HIGHS THURSDAY AND FRIDAY WILL BOTH STRUGGLE INTO THE MID 40S...MAYBE APPROACHING 50 IN THE FAR SOUTHERN ZONES ON FRIDAY. MINS THURSDAY NIGHT WILL DROP WELL INTO THE 20S AWAY FROM THE COAST...BUT BE MUCH WARMER FRIDAY NIGHT...30-35...DUE TO CLOUDS AND WIND BEFORE COLD ADVECTION DEVELOPS LATE. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 300 AM WEDNESDAY...EXTREMELY COLD TEMPERATURES FOR THE WEEKEND WILL SLOWLY MODERATE NEXT WEEK BEFORE A LOW PRESSURE SYSTEM IMPACTS THE REGION LATE IN THE EXTENDED. ANOMALOUS TROUGH ACROSS THE EAST STRENGTHENS OVER THE WEEKEND AS A PIECE OF VORT ENERGY DRIVES A COLD FRONT OFFSHORE ON SATURDAY. 850MB TEMP PLUMMET TO NEAR -15C...WARMER THAN PREVIOUS GUIDANCE BUT STILL VERY COLD...AND AS THE CORE OF THE COLDEST AIR MOVES OVERHEAD LATE SATURDAY AND SUNDAY...HIGHS AND LOWS MAY BE CLOSE TO 30 DEGREES BELOW CLIMO. SUNDAY MORNING LOWS ARE FORECAST TO BE IN THE MID TO UPPER TEENS...WITH HIGHS ON SUNDAY LIKELY REMAINING RIGHT AROUND FREEZING. AFTER ANOTHER COLD NIGHT SUNDAY NIGHT TEMPS BEGIN TO MODERATE AS THE LONGWAVE TROUGH AXIS SHIFTS OFFSHORE ALLOWING FOR SUBTLE SHORTWAVE RIDGING AND A PERIOD OF RETURN FLOW AT THE SURFACE AHEAD OF THE NEXT SYSTEM. THIS WILL BRING TEMPS WARM ENOUGH FOR THE TUESDAY LOW PRESSURE TO LIKELY BE AN ALL-RAIN EVENT...BUT IT WILL NEED TO BE MONITORED CLOSELY FOR ANY PTYPE ISSUES. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... AS OF 12Z...CONTINUED COLD/ARCTIC AIR ADVECTION ALONG WITH LOWER DEWPOINTS WILL PUSH ACROSS THE AREA THIS PERIOD. LOOK FOR 260-280 WIND DIRECTIONS THRUOUT...WITH SPEEDS 10-15 KT EARLY THIS MORNING AND THIS EVENING...10-20 KT WITH GUSTS 24 TO 28 KT DURING THE LATE MORNING AND AFTERNOON DUE TO MIXING OF THE STRONGER WINDS ALOFT TO THE SFC. EXTENDED OUTLOOK...PREDOMINATELY VFR. EXPECT W TO NW WINDS GUSTING UP TO 15 TO 25 KT THURSDAY...AND 20 TO 30+ KT DURING SATURDAY INTO SUNDAY. CHANCE OF PRECIP ON FRIDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 930 AM WEDNESDAY...NO CHANGES TO THE COASTAL WATERS FORECAST THIS MORNING AS THE STRONG SMALL CRAFT ADVISORY REMAINS INTACT. WILL CONSIDER A SHORT TERM MWS FOR BLOW OUT TIDES FOR THE GRAND STRAND THIS AFTERNOON DEPENDING ON TRENDS. PREVIOUS DISCUSSION FOLLOWS: SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR ALL WATERS...THROUGH THURSDAY MORNING. THIS A RESULT OF A TIGHTENED SFC PG COMBINED WITH CONTINUED COLD AIR ADVECTION OR ARCTIC AIR ADVECTION SURGES RESPECTIVELY. THIS COLD/ARCTIC AIR WILL BE ADVECTING ACROSS SSTS IN THE 40S AND 50S WHICH WILL ALLOW THE STRONGER WINDS JUST OFF THE DECK TO MIX DOWN TO THE OCEAN SURFACE. WINDS WILL BASICALLY RUN 260-280 DEGREES AT 20 TO 25 KT WITH GUSTS UP TO 30 KT...AND VEER SLIGHTLY TO 280-300 DEGREES AT 15 TO 20 KT TONIGHT. WILL SEE GUSTS UP TO 25 KT THIS EVENING. DUE TO THE OFFSHORE NATURE OF THE WINDS...THE HIGHER WIND SPEEDS WILL PRIMARILY OCCUR OVER THE OUTER WATERS WHERE THERE IS LESS FRICTIONAL EFFECTS FROM LAND. THE EXCEPTION ARE THE WATERS SOUTH OF CAPE FEAR TO LITTLE RIVER INLET...WHERE WESTERLY WIND DIRECTIONS ARE NEARLY PARALLEL TO THE COAST. BUT THIS WILL CHANGE TONIGHT WHEN WIND DIRECTIONS VEER TO THE NW...A TRUE OFFSHORE DIRECTION FOR ALL ILM WATERS. SIGNIFICANT SEAS WILL RUN 3 TO 7 FT...WITH A FEW 8 FOOTERS POSSIBLE ACROSS THE OUTER WATERS OFF CAPE FEAR. DUE TO A SLIGHTLY LONGER FETCH FOR WHICH TO BUILD SEAS UPON...THE WATERS BETWEEN CAPE FEAR SOUTH TO LITTLE RIVER WILL HAVE LESS OF A RANGE. AS WINDS VEER TO THE NW...A TRUE OFFSHORE COMPONENT FOR ALL WATERS...SEAS WILL HAVE A RANGE FROM 2 TO 3 FT NEAR SHORE TO 4 TO 5 FT OUTER WATERS...EXCEPT UP TO 6 FT POSSIBLE OFF CAPE FEAR. SHORT PERIOD...4 TO 6 SECONDS...WIND DRIVEN WAVES WILL DOMINATE THE SIGNIFICANT SEAS SPECTRUM. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... AS OF 300 AM WEDNESDAY...GUSTY NW WINDS WILL PLAGUE THE WATERS MOST OF THE SHORT TERM BEHIND A COLD FRONT JUST BEFORE THIS PERIOD...AND AGAIN LATE FRIDAY BEHIND A WEAK WAVE OF LOW PRESSURE. MOST OF THURSDAY...AND THEN AGAIN LATE FRIDAY...WINDS ACROSS THE WATERS WILL BE FROM THE NW AT 10-20 KTS. IN BETWEEN...THE AFOREMENTIONED LOW PRESSURE WILL CAUSE A FLUCTUATION IN THE GRADIENT AND WINDS TO VEER TO THE NE AROUND 10 KTS...DEPENDING ON THE EXACT TRACK OF THIS LOW PRESSURE...BEFORE RETURNING TO THE NW QUICKLY AS MENTIONED ABOVE. SEAS WILL BE PRIMARILY WIND-WAVE DRIVEN...WITH SOME RESIDUAL 6 FT SEAS NECESSITATING THE SCA TO CONTINUE INTO THURSDAY BEFORE FALLING TO JUST 1-2 FT BY FRIDAY AS THE OFFSHORE WINDS AND DECREASING SPEEDS DRIVE LOWER AMPLITUDES. RENEWED 2-4 FT SEAS WILL DEVELOP LATE AS THE WINDS INCREASE ONCE AGAIN. LONG TERM /SATURDAY THROUGH SUNDAY/... AS OF 300 AM WEDNESDAY...GUSTY WINDS FOR THE WKND WILL INITIALLY BE NW AT 15-25 KTS...BEFORE SLOWLY VEERING TO THE NE ON SUNDAY WHILE REMAINING AT ELEVATED SPEEDS. ALTHOUGH THIS WIND DIRECTION FEATURE A SIGNIFICANT OFFSHORE COMPONENT...THE STRONG VELOCITIES WILL PUSH SEAS UP TO 4-6 FT LATE SATURDAY AND INTO SUNDAY BEFORE WAVE HEIGHTS DROP BACK TO 2-3 FT LATE IN THE WKND. A SMALL CRAFT ADVISORY WILL LIKELY BE REQUIRED FOR ALL THE WATERS FOR PORTIONS OF SATURDAY AND SUNDAY. && .TIDES/COASTAL FLOODING... AS OF 630 AM WEDNESDAY...A COASTAL FLOOD ADVISORY HAS BEEN ISSUED FOR THE LOWER CAPE FEAR RIVER...IN EFFECT FROM 9 AM THRU 1 PM TODAY. LATEST FORECASTS FROM THE SURGE MODELS INDICATE THE DOWNTOWN WILMINGTON GAGE READING ON THE LOWER CAPE FEAR WILL PEAK AROUND 6.1 FEET MLLW AT HIGH TIDE...WHICH IS 1045 AM. FLOODING BEGINS AT 5.5 FT MLLW. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...COASTAL FLOOD ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NCZ107. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THURSDAY FOR AMZ250-252- 254-256. && $$ SYNOPSIS...JDW NEAR TERM...DCH/SHK SHORT TERM...JDW LONG TERM...JDW AVIATION...DCH MARINE...DCH/JDW TIDES/COASTAL FLOODING...DCH

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