Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 141645 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1245 PM EDT Sat Oct 14 2017 .SYNOPSIS...
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Onshore winds will bring a good share of clouds over the eastern Carolinas through the weekend, accompanied by mild daytime temperatures. A cold front will cross the coast Monday, bringing much cooler, and drier air Tuesday through mid-week. A slow warming trend will prevail into late week.
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&& .NEAR TERM /THROUGH TONIGHT/... As of 1012 AM Saturday...Adjustments were made to strengthen the sensible weather effects of the stratus surge which has over- spread SE NC and NE SC. As a result, the main elements altered were to lower maximums, and increasing the longevity of sky cover associated with the stratus. A transition should slowly begin to occur whereas stratus morphs into stratocumulus, but even so, we may be looking at mostly cloudy sky dome. Max Ts were lowered into the 70s. Patchy very light drizzle was also inserted into the morning grids per observations across the region. Dry and warm air aloft will squelch any updrafts and weak thermals today, so pop values held below mentionable thresholds. As of 300 AM Saturday...Very pleasant conditions will continue through the near term period. Mid level high pressure, centered well off to the southwest will combine with surface high pressure along the Appalachians to provide these conditions. There is an area of lingering stratus pushing south this morning that may hang on in the northeastern areas through part of today, but even this moisture should mix out eventually. Highs today will be in a narrow range of 80-83 with tonights lows in the lower to middle 60s. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 300 AM Saturday...The 500 mb ridge will break down Sunday night and Monday as a trough advances into the eastern United States. Sunday looks like our last breath of summer-like weather as highs soar into the mid 80s away from the beaches with a bubble of 850 mb temps of +17C to +18C overhead. Climatology suggests this might be the last time this year we reach the mid 80s. Moisture will begin to increase late Sunday night as the trough approaches, but it will likely be Monday before measurable rain falls across the area. Modest convective instability coupled with low-level convergence along the front itself should be enough to produce showers. PoPs have been increased a bit to 50-60 percent, peaking Monday afternoon. Model isentropic analysis does not show any significant overrunning behind the front which gives us confidence there will be a fairly quick shutoff of precip late Monday afternoon or Monday evening. Cold advection at and below the 850 mb level Monday night will bring in the coolest air of the season, most likely exceeding the cool temperatures we experienced September 7-10 by several degrees. We`re predicting lows Monday night ranging from 48-52 inland, with mid 50s at the beaches. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 242 PM Friday...Central caption this period remains the arrival of Fall-like air late Monday into Tuesday in wake of a cold frontal passage. The cooling will serve to align absolute humidity and air temperatures more in line with climatology for middle October, but not necessarily cooler than `normal`. This period is essentially dry, except for a brief and narrow window of PCPN opportunity Monday in vicinity of the cold front, when a transitory spike in column moisture makes passage. It should be noted that QPF values associated with the front will remain nil to scant, likely a tenth of an inch or less. As a result, it seems fortunate we have recently received the rainfall that we did, because a prolonged dry period appears in the cards next week. The NE-E flow much of the upcoming week will spread a few maritime clouds from time to time as depicted in time-height plots of RH, but bouts of sunshine minutes will rack-up also. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/...
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As of 17Z...Challenging flight environment locally. Tenacious blanket of low stratus spread across NE SC and SE NC, covering most terminals presently, will begin to erode inland where the layer is thinner. What breaks do transpire this afternoon may very well fill in tonight as low-level RH already running high, saturates. As a result, unfavorable flight conditions AFT 2z-4z as MVFR CIGS lower to IFR. Even surface VSBYs may lower to 3SM or less as stratus lowers. A slow road to recovery appears likely Sunday, despite return flow, because it is a weak return flow. By 16Z Sunday however ceilings should lift to MVFR or develop breaks. Extended Outlook...Isolated to scattered MVFR/IFR produced convection is possible on Monday ahead of a strong cold front. MVFR stratus possible near the coast TUE/WED morning in blustery post-frontal NE wind.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 1012 AM Saturday...NE winds were bumped up to 15 kt for a portion of today and through morning per latest observations, otherwise no other significant changes were performed. Seas of 2-4 feet will remain a mix of NE and SE waves, both in wave periods around 9 seconds, and a moderate chop on top. As of 300 AM Saturday...Very quiet conditions have developed across the coastal waters this morning with winds now down in the single digits. A north to northeast flow of ten knots or less will continue for the next several hours via high pressure over the Appalachians. The flow weakens further this afternoon leaving a flow driven by a weak sea breeze. The direction will slowly work its way back to northeast by Sunday morning. Seas are currently 2-4 feet and should remain so through the short term period. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... 300 AM Saturday...Weak high pressure across the area Sunday will provide one last day of excellent coastal and beach weather. Light winds, dry weather, and unseasonably warm temperatures may be the last echo of summer we see for awhile. A reasonably strong cold front sliding southeastward through the Midwest on Sunday should reach the Carolina coastal waters Monday. The GFS model is faster than the NAM and suggests a morning frontal passage. By Monday afternoon winds should be northerly and will increase to 20-25 kt by Monday night as cool Canadian high pressure builds in from the northwest. LONG TERM /TUESDAY THROUGH WEDNESDAY/... As of 242 PM Friday...A difficult and rough marine period shaping up this time frame, as a cold frontal passage Monday afternoon to evening, opens the door to strong NE winds Monday night and Tuesday, before abating somewhat Wednesday. Small Craft Advisory conditions appear likely through at least Tuesday. Seas following the front will peak Tuesday at 4-8 feet, highest offshore and north of Cape Fear, lowest along inshore waters of Brunswick county. Cannot rule out 30 kt gusts given the warm SSTs aiding in mixing of stronger 975 mb wind barbs to the sea surface. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...MJC NEAR TERM...SHK/MJC SHORT TERM...TRA LONG TERM...MJC AVIATION...8 is the U.S. government's official web portal to all federal, state and local government web resources and services.