textproduct: Newport/Morehead City

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

1) Unsettled pattern expected through the weekend

2) Back to a more typical summertime pattern next week with high draped over the Southeast U.S.

DISCUSSION

KEY MESSAGE 1...This afternoon, a wavy frontal boundary stretches west to east from the Ohio Valley to the Mid-Atlantic. South of the front, a moistening southerly flow is ongoing across the Southeast U.S, with instability steadily building. Case in point, dewpoints today are about 5 degrees higher than yesterday across the board. There is still some residual dry air aloft, but it continues to erode and the PWATs are bumping up against 2" which is above the 90th percentile for this time of year.

For the rest of today, residual subsidence beneath upper ridging shifting offshore may hold convective coverage down some. However, with moisture and instability increasing, we still expect at least isolated convection to develop, primarily along sea/river/sound breezes. Later this evening and tonight, the above-mentioned cold front is forecast to dip into the northern counties of ENC, and this may support some continuation of convection in that area past sunset. Storm motions parallel to front may allow some training of convection, with a minor/nuisance-stayle flooding risk possible. With some residual dry air aloft, DCAPE is forecast to be around 1000j/kg, supporting a risk of gusty downburst winds of 40-50 mph.

Early Saturday morning, convection may be ongoing in the vicinity of the stalled front. There may also be some convection along the southern coastal areas thanks to an approaching shortwave and the diurnal land-breeze circulation. Through the day, PWATs continue to climb above 2" for the entire area. The above-mentioned shortwave is forecast to pass west of ENC, but should provide enough of a glancing blow combined with the seabreeze and an inland trough to support scattered convection capable of very heavy rainfall rates and gusty winds. The increased southerly flow should lead to a more progressive seabreeze which should also favor a more progressive nature to the convection. While this would limit the duration of heavy rainfall rates over any one location, the rates could be high enough to support minor hydro concerns, especially in urban areas. Of note, despite anomalous moisture and moderate instability, convective coverage on Saturday is less certain as the strongest forcing is expected to be outside of ENC. Despite moderate instability, weak shear and lower DCAPE should help to keep the severe thunderstorm risk at a minimum.

On Sunday, guidance continues the trend of slowing down the arrival of a cold front that will be dropping south out of Virginia. The front now looks to come through Sunday night. This points towards an extra day of moist and unstable conditions, with another round of scattered to perhaps numerous thunderstorms. Deep layer shear is forecast to slightly increase, but the overall severe thunderstorm risk continues to look low. With anomalous PWATs in place, heavy rainfall rates can be expected, with a continued risk of minor flooding impacts.

KEY MESSAGE 2...A much drier airmass is forecast to build in across the Eastern U.S. early next week in the wake of Sunday night's cold front. Additionally, guidance have trended a bit cooler within the developing northeasterly flow regime, offering a reprieve from the higher humidity over this weekend. From mid-week on, guidance differ on whether it warms up or stays milder. Additionally, guidance suggests a decent coastal trough may develop along what is leftover from this weekend's front. With ridging building in, this trough may slide west beneath the ridge and bring a return to unsettled conditions, especially along the coast by Thursday.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

Forecast confidence is moderate over the next 24 hours.

With increasing moisture and instability today, the risk of TSRA is expected to step up today compared to yesterday. That said, the coverage is expected to be isolated to, at worst, scattered. PROB30s will continue to be in the TAFs where confidence in TSRA activity is the highest. Later this evening into Saturday morning, guidance is once again showing a moderate signal for sub-VFR CIGs and reduced VIS in BR/MIFG/FG. The signal is more widespread tonight compared to last night, which may put all TAF sites within the risk area.

Outlook: There will continue to be a risk of TSRA through Sunday. Eventually, a cold front is forecast to move through Sunday night with drier and more stable air in tow, along with a reduced risk of TSRA. Drier conditions are expected to last into the middle of next week with a reduced risk of TSRA.

MARINE

South to southwest winds of 10-15kt are common across most waters this afternoon. The exception is across the northern coastal waters and the Albemarle Sound vicinity where winds have recently shifted to E or NE in the wake of a weak front. That front is forecast to remain mostly stationary through this evening, then lift back north as a warm front by Saturday morning. Southerly flow then prevails through Saturday afternoon. Seas are currently 1-3ft across the coastal waters, and this is expected to continue through Saturday. Through this evening, any thunderstorm activity should be confined to the inland rivers and sounds. The risk then shifts to the coastal waters tonight into Saturday morning. The risk moves back inland Saturday afternoon.

Outlook: The risk of thunderstorms will continue until a cold front moves through Sunday evening. A northerly wind shift will occur along this front, with northeasterly flow then continuing into next week. The strongest northeasterly winds (10-20kt) are expected Monday and Tuesday, with a period of 25kt winds possible for some waters. Confidence in 25kt winds is moderate. Seas will respond to the building winds, and are expected to peak at 4-7ft Tuesday into Wednesday.

MHX WATCHES/WARNINGS/ADVISORIES

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