Area Forecast Discussion
Issued by NWS Wilmington, NC

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046 FXUS62 KILM 050001 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 701 PM EST Sun Dec 4 2016 .SYNOPSIS... Low pressure moving up the coast will bring light rain tonight. After a break on Monday a stronger system will affect the region Monday night into Tuesday leading to a more substantial rainfall. Quiet and seasonable mid week weather will be followed by Arctic air arriving Thursday night. && .NEAR TERM /THROUGH TONIGHT/... As of 300 PM Sunday...Dense mid and high clouds have been traversing the Carolinas for 24 hours now courtesy of a powerful subtropical jet being steered by upper level low pressure over northern Mexico. Patchy light rain has been falling on and off all day from these clouds with trace to .03" totals in most locations so far. This should change rather dramatically tonight as a warm front developing along the Georgia coast swings northward to near the Carolina coast after midnight. Deep isentropic lift developing west of this boundary should lead to widespread rain breaking out this evening and persisting much of the night. Rainfall amounts don`t look quite as large as we were thinking 24 hours ago, but 0.35" to 0.60" totals are certainly plausible. Temperatures have been stuck in the 40s and lower 50s all day. While inland temperatures should hardly budge overnight, along the immediate coast look for temperatures to rise by 5-10 degrees overnight with the approach of the warm front. Low pressure developing almost overhead after midnight should drag the front back offshore before daybreak Monday. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Surface low pressure zipping away from the NC coast Monday morning will have pushed the front a good 150-200 miles south of the area by Monday afternoon. With the loss of isentropic lift there should actually be some breaks in the clouds Monday with rain chances dipping to only 10-20 percent by afternoon. Any lingering morning rain along the coast should wrap up really quickly with additional rainfall amounts less than a tenth of an inch after 7 AM. Highs Monday could approach 60 degrees, which is actually below normal but will feel wonderful after the dreary and cold Sunday we experienced. The big upper low over northern Mexico will finally eject out to the east Monday, leading to surface low pressure developing across the Deep South Monday night. Strengthening southerly flow ahead of this low should lift the stalled front northward again and bring it near the Carolina coast by daybreak Tuesday. Isentropic lift west of the front should again lead to widespread rain developing. With strong wind fields and advection of warm air northward, elevated instability should increase sufficiently that isolated thunderstorms will remain in the forecast for late Monday night into Tuesday. After the upper trough passes us by to the north Tuesday afternoon, precipitation should largely end with the front slowly sagging back offshore Tuesday night. Two interesting features in this forecast I wanted to mention: one is that the synoptic situation is actually favorable for a possible gravity wave event Tuesday. (a very stable surface airmass west of the front with unstable conditions aloft) Should a gravity wave develop across Georgia or South Carolina it would move eastward, persisting until it reaches the surface front at which point it should dissipate. Typically these waves produce wind gusts of 25-35 mph as they trickle along the back edge of a precipitation shield. Also, with nothing to scour out the low level moisture Tuesday and such low sun angles this time of year, stratus Monday night could lower into a widespread area of fog Tuesday which might persist much of the day west of the front. This could include the Pee Dee area plus Lumberton, Whiteville and Elizabethtown. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 3 PM Sunday...Fairly seasonable temperatures expected Wednesday and Thursday as a weak low level thermal ridge develops ahead of the impending Arctic front. Mid level flow will be out of the WSW and not favorable for deep moisture through the column. The boundary itself will thus likely move through rain-free but the change in airmass will be starkly noticeable by Friday as highs struggle their way into the mid 40s. Not much recovery is expected Saturday after a downright cold night Friday night featuring lows in the mid 20s. Saturday arguable may not feel as cold however as the wind stays light due to the high building overhead. As the high continues eastward Saturday night into Sunday some slow moderation will get underway. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... As OF 00z...High confidence MVFR flight conditions will deteriorate to IFR this evening at KFLO/KLBT. Although TEMPO IFR could occur at the coastal terminals mainly due to vsbys if heavier rain occurs before midnight, IFR in general at the coastal terminals should hold off until just after midnight. IFR will persist through 14-16Z at KFLO/KLBT, 15-17Z at the coastal terminals with improvement to MVFR then VFR by 18Z all terminals. Extended Outlook...IFR/rain likely Mon night through Tuesday night. MVFR becoming VFR Wednesday and extending into Thursday. Slight chance MVFR/showers Thurs night into early Fri. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 300 PM Sunday...High pressure along the Mid-Atlantic coast will weaken and move offshore tonight. A warm front developing along the Georgia coast will move northward tonight, ultimately reaching the beaches late tonight. Northeast winds should turn southerly after midnight. Low pressure developing overhead will push the boundary back offshore with northwesterly winds developing by daybreak Monday. Unfortunately for mariners, the approach of this system will lead to increasing winds and seas overnight, and it appears we should experience a period of 15-25 kt winds and 3-6 foot seas late tonight into Monday morning. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Low pressure moving out to sea late tonight will push the front 150-200 miles south of the area for Monday. North to northeast winds are expected much of Monday and Monday evening as a result. However the approach of low pressure from the Deep South will begin to tug this front northward again late Monday night, and the boundary is expected to sweep back across the waters as a warm front around daybreak Tuesday. This should allow wind directions to veer southerly again with another increase wind wind speeds to 15-25 kt. LONG TERM /WEDNESDAY THROUGH FRIDAY/... As OF 3 PM Sunday...Wednesday will offer up a weak pressure gradient and thus fairly tame winds. Seas will still be slightly agitated from the short term storm system, though well below any advisory or headline levels. Winds ramp up Thursday as the Arctic front approaches. This boundary looks to arrive a bit sooner than previously thought and may blast across the waters during the afternoon or evening. Small craft advisory may be needed Thursday night and/or Friday. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory from 1 AM to 10 AM EST Monday for AMZ250- 252-254-256. && $$ SYNOPSIS...MBB NEAR TERM...TRA SHORT TERM...TRA LONG TERM...MBB AVIATION...MRR

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