textproduct: Wakefield

WHAT HAS CHANGED

- Slight (level 2/5) excessive rain risk downgraded to a Marginal (level 1/5) risk for eastern VA and the MD Eastern Shore

KEY MESSAGES

1) Showers and some embedded storms are likely today, especially near the Chesapeake Bay and on the Eastern Shore. While severe weather is not expected, localized flash flooding will be possible.

2) Mainly dry with seasonable temperatures Sunday through Tuesday. Isolated to scattered diurnally driven convection returns by the middle to latter part of the week.

DISCUSSION

As of 305 AM EDT Saturday...

KEY MESSAGE 1...Showers and some embedded storms are likely today, especially near the Chesapeake Bay and on the Eastern Shore. While severe weather is not expected, localized flash flooding will be possible.

A weak stationary boundary remains just south of the forecast area this morning, roughly aligned along the NC/SC coast. There is also a broad trough axis aloft across most of the eastern CONUS. Locally, there is a ribbon of mostly light rain across the northern/northwest portions of the area. This conflicts with several earlier runs of various CAMS which depicted rather widespread overnight showers and storms, particularly across SE VA and NE NC. In fact, these areas are actually quite stable as of this writing with sfc temps in the lower 70s and dew points in the upper 60s, which yields low/near-zero sfc-based and MUCAPE. Any appreciable instability remains confined to our S, in closer proximity to the front. Therefore, really don't see much convective activity developing through around sunrise.

The front will (eventually) lift northward as we head into this afternoon. Model and WPC progs also depict weak low pressure developing in the vicinity of the Chesapeake Bay and Eastern Shore. This, combined with some low-level convergence, should be sufficient for showers to develop in these areas by late this afternoon and afternoon. Instability looks quite meager, especially early on in the day, so am not expecting widespread thunderstorms at this time. A moist atmospheric column (PWATS ~2.1" across the E/SE) and slow- moving activity will support a continued heavy rain and localized flash flooding risk. The 00z HREF also depicted a relatively impressive signal for heavy rain and some flash flooding in the Eastern Shore vicinity. However, all of the 00z members that comprised the ensemble suite are currently handling the ongoing activity extremely poorly. Therefore, confidence in the evolution of convection later today is low and some recent runs of the CAMs are less bullish about the overall coverage of showers and the associated heavy rain signal. WPC has removed the targeted "Slight" excessive rainfall risk (which was in place for eastern VA and the MD Eastern Shore) and replaced it with a broad "Marginal" risk. In summary, localized pockets of very heavy rain are possible, but the exact location is uncertain and the coverage may tend to be on the low side. All of this precludes the need for any Flood Watch at this time. Late this evening, convection from the Great Lakes and OH Valley, associated with the primary cold front and trough, could approach our Piedmont counties. However, diminishing instability and reduced forcing with eastward extent should allow for most of this activity to diminish as it moves eastward tonight.

Outside of any precip, temps will be quite "cool" for mid-late August and only in the upper 70s-lower 80s (some mid 80s possible SE). Skies will average mostly cloudy, with some clearing possible W of I-95 this afternoon.

KEY MESSAGE 2...Mainly dry with seasonable temperatures Sunday through Tuesday. Isolated to scattered diurnally driven convection returns by the middle to latter part of the week.

The weak front will finally move offshore late Sunday, as the main upper level trough axis shifts offshore and surface high pressure builds into the SE CONUS. The surface high will usher in a drier airmass with seasonable temperatures in the 80s and dew points in the 60s Sunday into early next week. A reinforcing intrusion of dry air is likely Monday night/Tuesday with dew points in the 50s looking likely (except 60s far SE). The high is progged to break down by Wed/Thu, with unsettled conditions and isolated- scattered aftn/evening convection returning mid to late week.

AVIATION /10Z SATURDAY THROUGH WEDNESDAY/

As of 615 AM EDT Saturday...

A frontal boundary remains just south of the area as of 10z, with most sites (stubbornly) remaining VFR. Still expect a period of lower CIGs at the terminals for a time this morning, especially at/near RIC and there could be very localized IFR CIGs. Additionally, the coverage of showers/storms is expected to increase over the next few hours and especially after 12z. While strong-severe storms are not expected today, IFR VSBYs are possible in any heavier showers. Remaining unsettled heading into the later half of the day with continued showers/storms expected (best chance SBY/PHF/ORF/ECG). CIGs should remain MVFR through most of the morning and should gradually lift to VFR by this afternoon and especially this evening. SBY potentially stays sub-VFR most of the day. Drying out tonight with VFR conditions returning, though can't rule out some patchy fog inland.

Outlook: Drying out tonight with VFR conditions returning Sunday morning through Monday. Some patchy fog could occur inland around or after 06z Sunday.

MARINE

As of 305 AM EDT Saturday...

Key Messages:

- Generally benign marine conditions are expected through the weekend into early next week.

- Showers and occasional thunderstorms are expected today, with diminishing chances of showers and thunderstorms Sunday into early next week.

Sub-SCA conditions are expected to prevail this weekend through much of next week. Weak high pressure is centered over Atlantic Canada early this morning, with a weak trough off the NC Outer Banks. The wind is E 5-10kt. Seas are 2-3ft, with ~1ft waves in the Ches. Bay. A weak trough lingers offshore today as a warm front lifts across the Mid-Atlantic coast. An E wind is forecast to increase to 10-15kt across the northern coastal/offshore waters this morning, before becoming SE ~10kt this aftn. Elsewhere, generally an E/SE wind ~10kt for the Ches. Bay, SE/S 5-10kt for the southern coastal/offshore waters, tidal rivers, and Currituck Sound. Numerous showers/tstms are expected today as the warm front lifts across the waters. The wind becomes SW 5-10kt tonight ahead of a weak cold front, which cross the coast early Sunday resulting in a wind shift to W 5-10kt. Another weak cold front crosses the coast early Monday with a brief wind shift to NW, before becoming W/SW with speeds remaining less than 10kt. Yet another weak cold front crosses the coast early Tuesday resulting in a brief wind shift to NNW. High pressure settles off the Southeast coast mid to late next week resulting in S/SW flow at or below 15kt. Seas are expected to be 2ft to occasionally 3ft for the next week, with 1ft to occasionally 2ft waves in the Ches. Bay.

A low rip risk will be maintained today, Sunday, and Monday. There is a period of increased onshore flow for the northern beaches this morning. However, the swell direction will be ~50 degrees for shore normal, which should result in more of a longshore current. This combined with shorter period nearshore waves should keep the rip risk at low for the northern beaches today.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...None.