Key MESSAGE 1, A large Nor'easter continues to spin off the coast of the Northern Mid-Atlantic this morning. Well south of the center of the system, the pressure gradient continues to relax, and this should continue to support winds stepping down compared to the past few days. As the winds weaken, and as the Nor'easter finally weakens and pulls further away from the region, swell energy will continue to decrease. While some coastal communities will continue to feel the effects of the rough surf and strong swell, the magnitude of impacts is expected to take a step down today. In light of this, the Coastal Flood Warning for Hatteras and Ocracoke Islands has now been transitioned to a Coastal Flood Advisory. Areas where dunes have been damaged or weakened, some minor flooding may continue through 1 or 2 more high tides (around 8:00am this morning and 8:00pm this evening). Additionally, water may be slow to recede where roads have been flooded over the past few days, even without additional sound or oceanside water level rises.
Of note, the one area where new, minor coastal flooding may occur is around Roanoke Island. Moderate westerly winds are expected to develop along the length of the Albemarle Sound for several hours today, and this may support elevated waters levels in the Croatan and Roanoke Sounds. It's unclear whether the winds will be strong enough for a long enough duration, but the potential exists for up to 1 ft of inundation around those sounds, and the Northern OBX Coastal Flood Advisory covers this risk.
KEY MESSAGE 2, An upper level ridge is forecast to build over the Southeast U.S. Later this week, but guidance has slowed down some on when this occurs. In light of this, the warmest temperatures of the week have trended towards the end of the week (Thursday/Friday). Beneath the ridge, warming low-level thicknesses and persistent southerly flow may allow inland highs to get back close to 90 degrees (roughly 10 degrees above normal as we head into the first few days of October). The humidity is forecast to steadily return as well, but with ridging in place, the chance of showers and thunderstorms looks to stay low for much of the week.
07z Sunday through Thursday Forecast confidence is moderate to high over the next 24 hours.
The biggest change to the aviation forecast overnight was to introduce a period of MVFR CIGs at KPGV and KEWN. Guidance has been struggling with the extent of these lower CIGs as they progress south out of Virginia. They appear to be associated with an area of low-level moisture advection on the southwestern periphery of the Nor'easter off the Northern Mid-Atlantic Coast. Short-term guidance is starting to catch up to the faster and more expansive trend, and is why KPGV and KEWN now have TEMPO groups for MVFR CIGs. The probability of MVFR conditions is lower for the remaining TAF sites, and the forecast continues to show VFR conditions overnight.
By Sunday morning, a drying westerly flow is forecast to ensue and this should lead to a quick reduction to any remaining MVFR CIGs. Those westerly winds are likely to be gusty at times, with gusts to 20kt forecast for several hours.
Outlook: Until the Nor'easter pulls fully away from the region, there may still be a low-end chance of SCT to BKN MVFR-level clouds, but in general, VFR conditions are expected to dominate moving into at least the first half of next week.
Northwesterly winds of 10-15kt this morning are forecast to become westerly by this afternoon, and may slightly build to 10-20kt. For the nearshore coastal waters, 25kt winds are not expected, but it will continue to be breezy. Winds finally lay down substantially by Monday as the gradient continues to relax. Of note, a weak area of low pressure may move through the area on Monday. While it is not expected to be strong, it may lead to varying wind directions during the day.
For the nearshore coastal waters north of Cape Hatteras, seas of 6- 8ft this morning should finally lay down below 6ft by early this evening. A seas-driven Small Craft Advisory remains in effect through then. For the outer coastal waters, seas of 7-10ft are forecast to last into early this evening. For all coastal waters, seas are forecast to lay down to 2-4ft by Monday.
Outlook: Several days of much-improved boating conditions are anticipated for much of the upcoming week. Light northerly winds Tuesday and Wednesday are forecast to become southerly Thursday and Friday. Seas of 2-3ft are forecast for much of the week as well.
Nc, beach hazards statement through this evening for ncz203-205. Coastal flood advisory until midnight EDT tonight for ncz203>205. High surf advisory until 8 am EDT this morning for ncz203-205. Marine, small craft advisory until 8 pm EDT this evening for amz150. Small craft advisory until 5 pm EDT this afternoon for amz152- 154.
