textproduct: Newport/Morehead City

WHAT HAS CHANGED

Little change from the previous forecast.

KEY MESSAGES

1) Warmer weather today but still dry ahead of an approaching cold front.

2) Wet weekend is likely as moisture associated with TC Isaias overspreads the Carolinas. Heavy rain is likely with highest amounts focused along the coast.

3) A few stronger thunderstorms are possible on Sunday.

DISCUSSION

KEY MESSAGE 1...Latest analysis this morning shows WNW to W low level flow on the southern periphery of a broad mid-level cyclone swirling over southeastern Canada. At the surface, high pressure that has been in control for the past couple days is beginning to weaken as it gives way to an approaching cold front currently draped across the Midwest. Low-level thicknesses will build today, aided by the aforementioned downsloping flow, will aid in temperatures rising above climo into the low to mid 80s. Closer to the coast, temperatures will be tempered a few degrees by a thick cirrus shield being pulled off of TC Isaias over the central Gulf.

KEY MESSAGE 2...The pattern begins to change after today 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, making landfall in the vicinity of Mobile Bay late tomorrow evening.

East of Isaias, a plume of tropical moisture, with anomalous 2"+ PWATs, is forecast to surge north through the southeastern CONUS over the weekend. The moisture, in tandem with enhanced low- level convergence and strengthening WAA along a developing warm front will support a period of moderate to heavy rain late Saturday into Sunday across all of ENC. Guidance continue to show a solid signal for around 1-2" of rain across much of the area. Average amounts have changed little, but probabilities for higher-end amounts continue to trend upward. This is especially true along the coast where frictional convergence will likely enhanced rainfall rates. NBM probabilities for amounts higher than 3" are now between 50-60% here, and above 4" probabilities are up to roughly 20-30% - only slightly higher than similar odds from Euro and GFS ensembles.

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. Areas from New Bern south remain in a Slight (Level 2 of 4) risk of excessive rainfall from WPC.

KEY MESSAGE 3...Steady increase in moisture through the weekend peaks on Sunday contributing to an increase in instability across portions of ENC, greatest south of Highway 264. Factors like cloud cover will determine how much we end up getting, but ensemble averages suggest CAPEs as high as 1000+ J/kg in some spots. While low- level forcing is in question, it's a setup that bears watching for a conditional severe thunderstorm risk. Machine learning guidance and EFI guidance have changed little from yesterday, still suggesting at least a marginal threat.

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 /12Z THURSDAY THROUGH MONDAY/

Patchy shallow fog is gradually coming to an end this morning per area webcams, although PGV may see another reported drop or two before 12z. VFR conditions otherwise persist today with winds slowly veering southwesterly as high pressure moves offshore and a dry cold front approaches from the north. Dry tonight but with plenty of high level clouds, which will aid in keeping fog chances low - less than 10%.

Outlook: Generally VFR conditions are expected to persist through at least tomorrow. 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 along the Outer Banks.

MARINE

Light and variable winds under 5 kt in place over area waters this morning with seas offshore hovering at 2-3 feet with periods of 6-7 seconds. Winds slowly turn out of the southwest later today ahead of an approaching dry cold front, but should remain at 10 kt or less through the day. Winds will veer northerly overnight as front pushes offshore, with a brief surge of up to 15-20 kt possible for a few hours.

Outlook: Attention 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 easterly winds as early as Sat PM up to 20-25 kt from Raleigh Bay south, then turning southeast to south by Sunday as the low lifts north of the Carolinas and overspreading 20-30 kt 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 be at their highest Saturday night into Monday morning. In addition to the winds, seas are forecast to build to at least 7-9ft at 7-8s. A warm front lifting north through the area appears supportive of a risk of thunderstorms as well, focused on Sunday.

MHX WATCHES/WARNINGS/ADVISORIES

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