Key MESSAGE 1, Southerly low-level flow beneath ridging aloft, plus strong heating with clear skies will support well above to near- record highs this afternoon. Please see the CLIMATE section for more details. For reference, normal highs in early October are around 80 degrees, and forecast highs are in the 80s to low 90s.
KEY MESSAGE 2, A plume of anomalous, and deep, moisture will get pulled north through the Southeastern U.S. In advance of a cold front 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 on Saturday, 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 Saturday afternoon into Saturday 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 2"+ PWATs 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.
On Sunday, guidance differ on how far north the front will get as it briefly lifts back north 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, 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. The highest rainfall amounts should be across the southwestern counties of ENC where there will be the potential for heavy rain both Saturday and Sunday (compared to just Sunday for the northeastern counties of ENC).
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 3, 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.
18z Friday through Wednesday Forecast confidence is moderate over the next 24 hours.
VFR conditions this afternoon will eventually give way to the development of low CIGs on Saturday as a cold front begins to move slowly south into ENC. Just prior to the arrival of the front, there may be a window of opportunity for BR/MIFG/FG to develop, and this continues to be reflected in the latest TAF forecast. While the TAFs only show MVFR/low VFR conditions for now, the potential exists for a period of IFR, or lower, conditions to develop early Saturday morning. The front, itself, is then expected to be accompanied by a more widespread area of IFR/MVFR CIGs in low stratus. However, guidance differ some on the timing of the front. A northeast wind shift will accompany the front as well.
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.
Benign boating conditions continue across ENC with light S-SWerly 5-10 kt winds and 1-2 ft seas across our area waters as high pressure persists offshore. S-SW winds build to 10-15kt late this afternoon Seas generally remain around 1-3 ft at 9-10 sec into early SAT morning.
Outlook (Sat through Tue): A front will be approaching the area from the NW and pass through with winds turning NNE and inc a bit to 10-20 kt for Nern marine zones by SAT afternoon. Increasing moisture plus weak instability lead to widespread showers with a few storms. At this time, conditions look to remain below SCA levels through the weekend, but a secondary front moves through Monday with SCA winds appearing likely later Mon into Tue with 15-25 kt winds and seas of 6+ ft.
Nc, none. Marine, none.
