textproduct: NWS Wilmington

WHAT HAS CHANGED

A Coastal Flood Advisory has been issued for the Cape Fear River at downtown Wilmington as well as for the northeast South Carolina beaches as this evening's high tide is expected to bring tidal flooding.

KEY MESSAGES

1) While unsettled weather is likely later this weekend confidence in rainfall amounts remains limited.

DISCUSSION

KEY MESSAGE 1...While unsettled weather is likely later this weekend confidence in rainfall amounts remains limited.

Showers and thunderstorms will spread over the region later this weekend, tangentially associated with recently formed TD 9. While direct impacts from the system, which is forecast to be a hurricane at landfall along the Gulf Coast early this weekend, seems unlikely, the storm will help lift a plume of tropical moisture over the Southeast. Have high confidence in an unsettled weekend with rain arriving Sat, spreading south to north. The big question, and still a point of uncertainty will be rainfall totals. There is potential for excessive rainfall amounts with precipitable water in excess of 2" and as high as 2.5" during the event.

The strength and evolution of ridging at 5h to the northeast will shape where the tropical plume is directed. It is worth noting that the 3 major ensembles (CMC/EC/GFS including the AI variants) continue to show probabilities for total rainfall greater than 2" at 50% or less with minimal probability for rainfall in excess of 4". However, just to the south and west, as well as farther offshore, there are higher probabilities. Despite precipitable water values AoA daily record max values Sat into Sun, once the isentropic lift and low level convergence shift north Sat night, forcing is limited and lapse rates are not impressive. On Sun widespread cloud cover will limit surface based instability which may limit convective coverage.

Going back to the key message, have high confidence in widespread showers and thunderstorms this weekend, but there are several factors at play and while it is possible portions of the forecast area end up with significant rainfall (in excess of 3"), it is also possible the bulk of the higher rainfall amounts end up on the periphery of the forecast area. Should see solutions converge with the next few runs as better sampling of the environment around TD 9 helps, allowing for refinements to the specifics of this weekend's forecast.

AVIATION /13Z WEDNESDAY THROUGH SUNDAY/

VFR for the valid TAF period. Remains of a front offshore continue drifting southeast, taking mid-level moisture with it, but continue to see some higher clouds streaming northward, mainly along the coast. Otherwise clear skies expected with light NE winds.

Extended Outlook...VFR through at least Friday evening, outside of any patchy morning fog. Flight restrictions likely to return Saturday or Sunday.

MARINE

Decreasing northeast flow has allowed seas to fall under 6 ft and the Small Craft Advisory has been ended. Winds and seas will continue decreasing into Thu, with flow remaining northeast. Benign marine conditions Thu/Fri before gradient starts to respond to what the tropical system in the Gulf. Confidence in no direct impacts from what is currently TD 9, but northeast flow will start increasing Fri night and by Sat headlines are likely to be required as prolonged, enhanced northeast flow builds seas. Winds will veer to east Sat night and then southeast to south for Sun. Peak gradient winds appear to be Sat night, with the easterly component helping push higher seas offshore well into the nearshore waters. So while marine conditions will be nearly ideal Thu/Fri expect conditions to quickly turn treacherous this weekend.

ILM WATCHES/WARNINGS/ADVISORIES

NC...Coastal Flood Advisory from 6 PM to 10 PM EDT this evening for NCZ107. SC...Coastal Flood Advisory from 5 PM this afternoon to 7 PM EDT this evening for SCZ054-056. MARINE...None.