textproduct: Newport/Morehead City

WHAT HAS CHANGED

Winds have slightly increased over the weekend.

KEY MESSAGES

1) Warming trend into the weekend, along with next chance for rain, potentially heavy.

DISCUSSION

KEY MESSAGE 1...Warming low-level thicknesses, possibly aided by a downsloping west to northwest low-level flow, should support above normal temperatures on Thursday. The one caveat is high clouds which may prevent highs from getting as warm as low-level thickness values might otherwise suggest.

Beyond Thursday, the pattern begins to change as an upper level ridge shifts east from the TN Valley to the Carolinas. Meanwhile, a cutoff low is forecast to develop over east Texas. The flow between these two features should help to steer TC Isaias north through the Gulf and towards the Gulf Coast. The latest forecast track from the NHC brings Isaias north through the TN and OH Valleys Saturday and Sunday after making landfall near the FL/AL coast. East of Isaias, a plume of tropical moisture, with anomalous 2"+ PWATs, is forecast to surge north through the Southeast U.S. this weekend. The moisture in tandem with enhanced low-level convergence and strengthening WAA along a developing warm front should support a period of moderate to heavy rain late Saturday into Sunday across all of ENC. Guidance continue to show a solid signal for 1-2.5" of rain across much of the area. While the area average amounts haven't changed much, the higher end of available guidance has increased some. Those higher end amounts (2-4") will likely be focused where convection develops. Initially, this will likely be focused along the coast, and for now this is where the greatest potential exists for 2"+ amounts. The precipitation is expected to trend more showery in nature later Sunday into Monday as the better forcing shifts away from the area. 6hr Flash flood guidance is around 2-4" for the areas of ENC that saw heavy rainfall a few days ago, while the rest of the area is 4"+. With area averages forecast to fall below these ranges, and over a longer period of time, the risk of significant hydro impacts appears low. That said, any convection that develops will be capable of intense rainfall rates, with rate-driven flooding of poor drainage and urban areas possible.

Of note, based on the latest guidance, and NHC track, the remnants of Isaias may pass a bit closer than previously forecast. While this doesn't change the forecast significantly, it does edge the stronger gradient (between the TC remnants and a strong high offshore) east some. Because of this shift, winds have increased some with this forecast. Along the coast, a period of 30-40 mph wind gusts appears possible, especially Saturday night into Sunday night.

One other potential hazard we will be watching is thunderstorms. As mentioned previously, the greatest instability, and risk of thunderstorms, is forecast to remain offshore. However, the inland track of the remnants of Isaias should put ENC in the warm sector on Sunday, and recent guidance suggests an area of weak to moderate instability may develop Sunday afternoon depending on the track and timing, cloudcover, etc. While low- level forcing is in question, it's a setup that bears watching for a conditional severe thunderstorm risk. Machine learning and EFI guidance have recently picked up on this, and have trended higher with severe probs.

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 a lower chance of showers and thunderstorms by Tuesday.

AVIATION /00Z THURSDAY THROUGH MONDAY/

VFR conditions currently across the terminals early this evening. High pressure will remain anchored over, or near, ENC over the next 24 hours, which will support light winds. Additionally, a very dry airmass in place should limit low-mid level cloudcover. However, expect increasing high clouds overnight into Thu. The one caveat overnight is the potential for MIFG/BR into early Thursday morning. Cirrus clouds overhead, plus the dry airmass, appear to be limiting factors for a greater FG risk. However, outside of the high clouds, decent radiational cooling conditions are expected tonight, so the probability isn't zero.

Outlook: Generally VFR conditions are expected to persist through at least Friday. Conditions change over the weekend as tropical moisture gets pulled north off the Gulf and into the Carolinas. This will support periods of low CIGs, widespread RA, and potentially a TSRA risk. Gusty southeast to south winds are likely as well, especially Saturday into Sunday.

MARINE

Modest northeasterly winds of 10-15 kt this afternoon are expected to lay down to around 5-10kt by tonight as high pressure edges closer to the area. With winds laying down, seas are expected to hold in the 2-3ft range. Good boating conditions then continue into Thursday.

Outlook: A modest northeasterly surge of wind is expected on Friday as the gradient tightens across the area. Winds are expected to build to 10-20kt during this time, but are currently expected to stay below 25kt, and marine headlines appear unlikely. Attention then turns to the weekend as the remnants of TC Isaias move inland through the Gulf Coast States. While the system is forecast to remain well west of ENC, the gradient will further tighten between that system and a strong surface high over New England. This is expected to support southeast to south winds building to 20-30kt for most waters with higher gusts. Marine headlines are likely from this weekend into early next week. For most waters, this looks like a strong small craft advisory type of event. For the outer coastal waters, winds may be strong enough to support gale headlines. Winds are expected to peak Saturday night into Monday morning. In addition to the winds, seas are forecast to build to at least 6-8ft at 7-8s. A warm front lifting north through the area appears supportive of a risk of thunderstorms as well.

MHX WATCHES/WARNINGS/ADVISORIES

NC...None. MARINE...None.