textproduct: NWS Wilmington

WHAT HAS CHANGED

Rainfall totals continue to decrease, but confidence is high in rainfall occurring on Sunday. A Small Craft Advisory has been issued for seas in excess of 6 feet, beginning early Sunday evening and continuing through late Monday.

KEY MESSAGES

1) Beneficial rainfall will occur Sunday through Monday morning. Rainfall amounts continue to decrease, but confidence in where the heaviest rainfall will occur has increased.

DISCUSSION

KEY MESSAGE 1... Beneficial rainfall will occur Sunday through Monday morning. Rainfall amounts continue to decrease, but confidence in where the heaviest rainfall will occur has increased.

Confidence remains high in widespread rainfall beginning mid-day Sunday. HREF guidance indicates that showers will begin to develop over central SC with increasing synoptic lift and deep moisture. A second area of showers will develop along an inland-moving coastal trough near coastal NC/SC as early as mid to late morning. Both areas of shower activity will expand by early to mid afternoon. The southern Pee Dee area will likely be the last to see the consistent radar echoes. Steadier rain should become widespread by late afternoon or early evening. The southern Pee Dee more likely by Sunday evening. Rain will become less uniform after midnight with showers persisting into early Monday.

Rainfall amounts continue to plague the forecast. What was a widespread potential for nearly an inch of QPF a few days ago has decreased for parts of our area. With HREF guidance starting to encompass the entire event, LPMM QPF has decreased yet again for portions of the Pee Dee. The I-95 corridor and points just east, such as Florence, Dillon, and Marion have dropped to just 10%-20% for QPF greater than 0.50 inches and around 50% for QPF exceeding 0.25 inches. The ensemble mean here is around 0.40 inches, much less than just 24 hours ago. This is likely due to the split in lift to the west of I-95 and near the coast. The disturbance has also increased in speed over the past several model cycles, ending early Monday morning. This is mostly seen in the hi-res ensemble depiction with global models holding onto showers slightly longer into Monday.

Rainfall elsewhere has also decreased, but to a lesser extent. Probabilities for Wilmington and coastal southeast NC exceeding 0.50 inches remains upward of 70%-80% with the 25th-75th around 0.60 inches to 0.90 inches. These will likely be the wettest areas within our CWA. Spreads increase for the rest of the area depending on the exact location of a "forcing gap," but generally favor ensemble means in the neighborhood 0.40 to 0.75 inches of QPF.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

VFR for most of the period. Clouds towards its end will gradually lower and thicken and some light rain may start appearing on area radar, moving in from the west. Most of the lowered flight categories will come after 18Z.

Extended Forecast... Flight restrictions likely midday Sunday into Monday as a low pressure system affects the area. VFR returns early next week.

MARINE

Through Sunday... Quiet weather through the near term as high pressure initially centered north of the area slides offshore towards the end of the period. There will not be any appreciable swell energy near shore leaving the diminutive wind waves the only.

Sunday Night through Wednesday... Seas build on Sunday as a result of the extended southerly fetch. Seas should exceed 5-7 feet by the early evening. Conditions will be most hazardous during the evening until just after midnight. Some late day sea fog is possible as dew points surge.

Northerly winds on Monday will keep seas elevated. Slow improvement is expected, but seas will likely remain in excess of 6 feet through the afternoon for SC nearshore waters and early evening for NC nearshore waters. SCA is split due to uncertainty in the timetable for improving conditions for the NC nearshore waters on Monday evening. Cold air advection late Monday could extend the hazardous seas a bit longer than is currently advertised. Again, confidence was low in this region, so some refinements may be needed as the event comes to a close on Monday.

High pressure dominates early next week. High pressure shifts offshore on Wednesday with return flow producing a noticeable gradient. I carried the adjustment from the previous forecast which tunes the known NBM high-wind bias in warm advective flow. Forecast advertises wind speeds near 15-20 knots with a slight increase in wind speed probs for the period over previous guidance. SCA may be needed possible, but will hold on mentioning elsewhere given the known bias.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...None. MARINE...Small Craft Advisory from 6 PM Sunday to 7 PM EST Monday for AMZ250-252. Small Craft Advisory from 6 PM Sunday to 1 PM EST Monday for AMZ254-256.