Key MESSAGE 1, A plume of tropical moisture characterized by 2"+ PWATs and dewpoints in the 70s is forecast to continue to overspread the Carolinas to the east of the northward-advancing remnants of TC Isaias this morning. At the surface, a warm front/coastal trough (currently just south of the area) will trudge north along the southeastern coastline, likely with a weak, non- tropical area of low pressure developing along it. Now it appears the main axis of convection will remain over the Gulf Stream, with heavy storms offshore robbing some of the rich moisture advection into ENC. This has been a notable trend with most of the CAMs the past several runs. For this reason, have cont to trend down with QPF, especially inland. Most model estimates the potential for several inches along the immediate coast, with much lower amts less than an inch or so for the interior Coastal Plain counties. Will continue Flood Watch for areas along the coast, effective through through this afternoon, though bulk of widespread rain will be over by mid morning.
KEY MESSAGE 2, Possibility of convective elements reaching the coast would warrant a tornado risk early this morning as the aforementioned warm front lifts through ENC. Plenty of low level helicity in place with the inc serly flow in place and strong veering wind profile downstairs. The greatest tor threat would likely be focused near the srn/sern coast where some better instability advects onshore. Later today, flow becomes more unidirectional with swrly low level winds ensuing during the afternoon. While helicity wanes, better instability will be in place due to daytime highs expected in the low 80s and TD's surging through the mid 70s. Will have to watch for a severe threat this afternoon ahead of the cold front, with best chances appearing for the interior zones, where NCAR/HRRR svr probs are highest. Main concern this afternoon will be potential for iso damaging wind gusts.
The remnants of Isaias are forecast to round the upper level ridge and move off the Northern Mid-Atlantic Coast early next week. Drier air then moves in behind it with drying conditions developing tonight into Mon.
KEY MESSAGE 3, Strong onshore winds, building seas, and higher than normal astronomical tides may support some coastal impacts through early Mon. There remains uncertainty on the magnitude of impacts, especially given the shorter-duration of the stronger winds, as well as what should be a weaker swell and periodicity compared to the recent Nor'easter. With that in mind, there will be an increased risk of rip currents and large waves, at a minimum. High Surf Advisory remains in effect between Ocracoke and Oregon Inlets. Additionally, some of the most vulnerable locations along the Outer Banks may see at least some minor issues, especially with this morning's high tide (7-9am). There may also be some very minor (sub advisory) coastal flooding around sounds and tidal waterways around the Crystal Coast due to the higher astronomical tides.
09z Sunday through Thursday Widespread IFR conditions persist across the terminals early this morning with periods of light rain and drizzle. Brief period of LLWS possible across all terminals the next few hours with a SE jet at 40-45 knots around 2kft. This jet will quickly shift to be out of the SW behind a warm front progressing northward. Periods of rain will bring vsbys down to 3-5 sm ocnl, with thunder threat mainly east of the TAF sites this morning, except MRH. Cigs will be slow to lift today, likely becoming MVFR by late morning and afternoon, and VFR this evening. A few thunderstorms possible this afternoon ahead of an approaching cold front, though coverage and chances will be dependent by how much cloud cover lingers this morning.
Outlook (Mon through Thu): Pred VFR conditions expected through the period as high pressure builds in. Breezy NW winds expected Mon.
Dropped Gales for nearshore coastal waters, continues for some offshore zones. Scas continue for the nearshore waters and sounds. Latest obs show S-SE winds 15-30 kt across the waters, with seas 6-12 ft. A warm front will continue to lift northward through the waters this morning, with winds veering and becoming southerly. Winds and seas will slowly diminish but remain breezy to strong through the day. Scas and Gales continue for the waters and sounds. Breezy to strong S-SW winds will continue tonight behind the front, becoming more westerly early Mon morning. Seas 5-9 ft this evening will grad subside to 4-8 ft early Mon.
For the convection threat, strong to severe thunderstorms containing waterspouts are possible early this morning over the Gulf Stream waters as low pres travels along a slow moving warm front. After a break in storms mid morning, additional showers and storms are possible later this afternoon into the evening ahead of a cold front, with precipitation finally clearing eastward later tonight.
Outlook (Mon through Thu): Behind a cold front tonight, gusty wrly winds are expected to develop, with SCA conditions for most of the sounds and nearshore coastal waters through Monday morning and afternoon. High pres eventually builds in later Mon through mid week, with winds and seas diminishing. Another front will push through the waters later in the week, likely Thursday.
Nc, flood watch until 2 pm EDT this afternoon for ncz047-081-092- 094-194>196-198-199-203>205. Beach hazards statement through this evening for ncz195-196- 199-203>205. High surf advisory until 8 pm EDT this evening for ncz204-205. Marine, small craft advisory until 8 am EDT Monday for amz131-230-231. Small craft advisory until 11 am EDT Monday for amz135. Small craft advisory until 2 pm EDT Monday for amz150-152-154- 156-158. Gale warning until 10 am EDT this morning for amz180. Gale warning until 2 am EDT Monday for amz182-184.
