Area Forecast Discussion
Issued by NWS Wilmington, NC

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KILM 031421 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 921 AM EST Sat Dec 3 2016 .SYNOPSIS... High pressure will move offshore Sunday night. A complex storm system will bring periods of heavy rainfall late Sunday through Tuesday. Cool and dry high pressure will follow this system for mid-week. A true Arctic front will cross early Friday, ushering in the coldest air since last winter. && .NEAR TERM /THROUGH TONIGHT/... As of 930 AM Saturday...Temps are rising through the 40s and should reach 54-58 for highs this afternoon. Cirrus clouds will arrive from the west within an increasingly moist 400-200 mb subtropical jet originating over the Pacific Ocean and accelerating eastward across Mexico and the Gulf Coast. Changes with this morning update were very minor. Discussion from 600 AM follows... The low level flow will be from the N and NE. Satellite imagery shows considerable higher clouds racing across the southern CONUS. Model profiles show this moisture increasing above 15 kft today with mid level ceilings beginning to materialize tonight. Thus, sunshine will be more filtered as compared to recent days. Given temps at 850 mb will only be in the single numbers and sunshine will be increasingly filtered, forecast highs are not expected to exceed the mid 50s. The clouds tonight should help to keep temps from falling below the mid 30s to around 40. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 300 AM Saturday...Chilly high pressure will be centered just to our N Sunday. The high will move off the coast Sunday night. At the same time, a very wet southern stream system will be organizing along the Gulf Coast. Warm and moist air will override the cool airmass near the surface and isentropic lift will be on the increase. Clouds should be plentiful on Sunday. Moisture should be streaming N and E and it is possible light rain will break out during Sunday afternoon, especially across the Pee Dee and Interstate-95 corridor. A warm front is expected to develop to our S and along the southeast coast Sunday night. The lift associated with this feature is expected to increase the risk for rainfall and have increased POPs to categorical. Monday and Monday night, strengthening low pressure is expected to move from the western Gulf Coast and across the mid south. A warm front will extend eastward from the low. Another area of low pressure may begin to develop along the offshore coastal front. A southwest low level jet of 50-60 kt will bring copious moisture up and over the front to our S. Precipitable water values will be near 2 inches while the depth of moisture becomes very deep. Thus, will show POPs as high as categorical. Rainfall rates should increase given the increasing lift and moisture supply. Will add mention of heavy rain. The frontal system is expected to remain to our S and E through 12z Tue and so will keep any mention of thunderstorms offshore where instability should be highest. We are still expecting a soaking rain with amounts through Tue in the 1 to 2 inch range and as high as 3 inches. High temperatures will be below normal through the period, mainly in the lower to mid 50s Sunday and mid and upper 50s Monday. Low temperatures will be in the 40s Sunday night and mid 40s to mid 50s Monday night, highest at the coast. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 300 AM Saturday...An active pattern continues next week, and the extended will begin with a potentially high-QPF rain event. Low pressure developing along the Gulf Coast will move NE, with secondary re-development likely along the Carolinas Coasts. High pressure in place ahead of this feature will slowly erode to the NE, with strong isentropic lift in an environment with increasing PWAT driving periods of heavy rainfall Tuesday. While initially the precip characteristic will be stratiform, recent guidance has shifted the secondary low track just inland, which could allow for more dynamic/convective rainfall late Tuesday. This can be ironed out as we get closer to the event, and what is more certain is significant rainfall, with the GFS ensemble plume mean centering near 2 inches in the timeframe ending Tuesday night. A cold front trails this system Tuesday night and seasonably cool and dry weather is forecast Wed/Thu before a strong trough digs into the Great Lakes driving an arctic cold front through the Carolinas on Friday. Moisture return ahead of this feature may be limited, so showers along the front are currently forecast to be light early Friday. More noteworthy is the polar air mass behind this front, and 850mb temps may approach -10C by the end of the period, signaling well below normal temperatures beginning Friday. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... As of 12Z...High confidence for VFR through the valid TAF period as high pressure remains in place. Expect FEW/SCT high clouds and northerly winds around 5 to 10 kts today. Tonight, winds will become light and variable with increasing mid to high level cloud cover, BKN/OVC in nature, ahead of an approaching system. Extended Outlook...A storm system will bring periods of MVFR/IFR late Sunday through Tuesday. Otherwise, expect VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 900 AM Saturday...High pressure building in from the upper Midwest is keeping a rather tight pressure gradient over the Carolina coastal waters, with recently observed wind gusts as high as 25 knots at the Frying Pan Shoals buoy, 17 knots at Wrightsville Beach, and 17 knots at the nearshore Sunset Beach buoy. These stronger winds should maintain themselves for the next several hours before diminishing this afternoon. An exercise caution headline will remain on the forecast north of Cape Fear through 1 PM. Discussion from 900 AM follows. A Small Craft Should Exercise Caution headline is in effect from Cape Fear to Surf City. High pressure building from the NW will keep the wind direction from the N today and NE tonight. Wind speeds will be up to 15 to 20 kt this morning with gusts up to 25 kt. Wind speeds for the remainder of the period will be 10 to 15 kt. Seas will be up to 4 to 5 ft this morning, highest across the outermost waters. Seas will subside to 2 to 4 ft this afternoon and 2 to 3 ft tonight. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... As of 300 AM Saturday...The center of high pressure to out N on Sunday will shift offshore Sunday night. A warm front and coastal front will develop Sunday night and then remain in close proximity Monday and Monday night. Return flow around the departing high will allow winds to veer from NE Sunday to E and SE Sunday night. The juxtaposition of the front will ultimately determine the wind direction for the remainder of the period. At this time, we think winds will tend to veer to S and SW across the waters late Sunday night into Monday as high pressure moves offshore. Developing low pressure along the front would tend to shift winds back to the NE during Monday with winds perhaps returning to E and SE overnight Monday depending on the evolution of the the coastal front. Wind speeds will be in the range of 10 to 20 kt through the period. Seas of 2 to 3 ft Sunday and Sunday night will build to 3 to 4 ft Monday and Monday night. LONG TERM /TUESDAY THROUGH WEDNESDAY/... As of 300 AM Saturday...Low pressure moving along the coast will create SCA conditions on Tuesday. Uncertainty remains into the strength and position of this system, but if the low stays along the coast or just inland as currently projected, S/SW winds of 15-25 kts will envelop the waters Tuesday, driving seas to 4-7 ft, and an SCA is likely. As the low pulls away Tuesday night, a trailing cold front will cross the waters turning winds to the NW, with wind speeds then slowly falling to around 10 kts by the end of the period. These lighter winds combined with the offshore direction will allow seas to fall to 2-3 ft during Wednesday. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...JDW NEAR TERM...RJD/TRA SHORT TERM...RJD LONG TERM...JDW AVIATION...SGL is the U.S. government's official web portal to all federal, state and local government web resources and services.