Key MESSAGE 1, A plume of anomalous, and deep, moisture will get pulled north through the Southeastern U.S. In advance of a two cold fronts this weekend. The front will initially move through ENC on Saturday, then stall offshore before lifting back north on Sunday. This will occur as a weak area of low pressure rides NE along the front. As the low moves off the coast, it will drag the front back south through ENC later Sunday into Sunday night.
Modest heating of a moist boundary layer should allow moderate instability to build ahead of the front today, especially across our southern counties south of HWY 70. It's there where we expect the greatest coverage of showers and thunderstorms to be focused this afternoon and evening. Guidance differ some on the progression of the front on Saturday, but with strong ridging centered offshore, it stands to reason that the progress of the front will be slowed, favoring a frontal passage during peak heating for our southern counties. Moderate instability plus PWATs AoA climo maximums for early October, suggests a risk of high rainfall rates at times. Ensemble guidance suggests 0.50-1.50" of rain, on average, in this area. However, where convection is the most persistent, rainfall totals may reach as high as 2-3". This may support a risk of urban and poor drainage flooding. 3-hr flash flood guidance is 3-4" in this area, which suggests the risk of flash flooding is low based on the potential higher- end amounts being below FFG. It's worth watching, though, given such high moisture content. As such, WPC has included this area, where the seabreeze and front will meet this afternoon, in a Slight Risk of Excessive Rainfall.
On Sunday, guidance differs on how far north the front will get as it briefly lifts back as a warm front. This doesn't appear to impact the ENC from a coverage standpoint. However, if the front were to lift further north, it could open up the potential for more instability to be available while the FA is warm sectored, which could support higher rainfall rates and amounts. This could also have an impact on temperatures. Regardless, increased low- mid level convergence interacting with a very moist airmass should lead to a widespread area of showers and isolated thunderstorms. For the area at large, the greatest coverage of showers and thunderstorms is expected on Sunday.
In total, 1-3" of rain appears likely for much of ENC over the weekend, 2-4" over the area from Greenville S and W. The highest rainfall amounts expected in an area roughly outlining Duplin Co to New Bern to Newport/Havelock to Jacksonville, where there will be the potential for heavy rain both Saturday and Sunday (compared to just Sunday for the northeastern counties of ENC). Highly localized weekend totals of 4-6" aren't out of the realm of possibility in this area.
The risk of severe thunderstorms continues to look low due to weak shear and weak mid-level lapse rates. However, perhaps a few water- loaded downdrafts of 30-40 mph will occur Saturday afternoon when instability is at its peak.
KEY MESSAGE 2, In the wake of the weekend front, a stiff NEerly breeze will develop and peak MON night into TUE. This will lead to building seas and elevated water levels. Astronomical tide levels will luckily be on the way down, but seas building to 7ft, though relatively choppy periodicity of 7 sec, but enough to lead to further beach and dune erosion concerns across the areas with severely diminished dune structures. Strongest winds of 20-25 kt with higher gusts expected MON night into TUE morning. Winds remain out of the N-NE into late- week, but speeds diminish to 10-15kt late TUE and beyond.
06z Saturday through Wednesday Main forecast concern tonight is the potential for fog/stratus development. Guidance is less bullish with developing it tonight compared to last night with winds still AoA 4kt for most of ENC. Href/refs probs reflect this with only around 30-50% chance of IFR or lower at best. Skies are expected to be mainly clear for most of the night with mainly thin high clouds, though could see increasing low clouds toward daybreak ahead of a cold front. Despite the ongoing low level mixing, SWern zones are likely to decouple in the early morning hours. Confidence for fog development is low giving the pluses and minuses and generally have MVFR vsbys late tonight but there is some potential for lower cigs/vsbys than forecast. Any fog that develops is expected to dissipate fairly quickly after sunrise.
A cold front will drop into northern rtes this morning and stall somewhere south of the Pamlico River in the afternoon. North of the front, expect MVFR to develop late morning and persist through the afternoon with the post frontal low level inversion. Along and south of the front there will be sufficient instability for shower and thunderstorm development bringing periods of sub-VFR conditions. Pw values will be surging to well above 2" and some storms could bring locally heavy rainfall. The front will push south through the area late afternoon and evening with convection waning with loss of instability. Ifr/lifr conditions expected to spread from N to S across all rtes with scattered showers continuing through this evening.
Outlook: A risk of low CIGs and TSRA will accompany a wavy frontal boundary that will waffle north and south across ENC over the weekend. The front will finally shift fully offshore and away from the area Sunday night into Monday. The wind direction will vary during this time as well, but will become predominantly north to northeast behind the front Sunday night into early next week.
Boating conditions start with winds SW generally 5-10kt early and seas around 1-2 ft. A cold front moves through the area today with a modest northerly surge of wind behind it tonight. Showers and storms possible over GStream waters. Southerly flow then briefly returns on Sunday as a weak area of low pressure moves through ENC, higher chances of more widespread showers and tstorms Sun.
Outlook (Sat through Tue): At this time, conditions look to remain below SCA levels through the weekend, but a secondary front moves through Monday with SCA conditions likely developing behind it across all coastal waters and larger inside waters, with winds 15-25 kt and coastal seas building to to 4-6ft, offshore 7-9ft. Winds peak TUE morning and remain NEerly and generally 10-15kt through the rest of the work-week.
Nc, none. Marine, none.
