textproduct: Wakefield

WHAT HAS CHANGED

Updated discussions.

Chances have increased for SCA conditions on Monday after a stronger frontal passage.

KEY MESSAGES

1) Continued unsettled and humid today. Widespread showers and a few thunderstorms early, then scattered afternoon showers/storms possible. Mainly dry with skies clearing tonight.

2) Mainly dry with seasonable temperatures and significantly lower humidity Monday-Wednesday. Temperatures warm back above normal late in the week an upper ridge builds back into the region. Next chance for rain Fri-Sat.

DISCUSSION

As of 345 AM EDT Sunday...

KEY MESSAGE 1...Continued unsettled and humid today. Widespread showers and a few thunderstorms early, then scattered afternoon showers/storms possible. Mainly dry with skies clearing tonight.

The latest WX analysis indicates a sfc warm front from northern VA to the MD eastern shore, with a sfc trough farther south across the VA/NC piedmont. The next batch of showers has developed across south-centra//central VA along the sfc trough, with another area of showers and some tstms across the NE portions of the FA near the warm front. There is decent low level wind shear near the warm front and less CIN so will be watching the eastern shore closely through the next few hrs for any potential stronger storms or quick spin- up circulations. Otherwise, just locally heavy rain through around 8-9 AM (with PWATs 2"+) before shower/storms diminish and push offshore and off to the NE as the warm front lifts away from the local area. Expect a lull in the precip for a few hrs, with some redevelopment likely this aftn as the early AM clouds lift and scatter out. Models show ML CAPE this aftn of 1000-1500 J/Kg, highest E of I-95. Highest chances will be across the SE, where 40-60% PoPs are forecast for a few hrs, though the CAMs also have honed in on some development across the mountains, so will have 20-30% PoPs moving in from the NW as well. There is no SPC outlook today but an isolated stronger storm is possible, along with locally heavy rain. Highs today generally in the mid-upper 80s. Drying out after sunset, with lows mostly in the upper 60s to lower 70s.

KEY MESSAGE 2...Mainly dry with seasonable temperatures and significantly lower humidity Monday-Wednesday. Temperatures warm back above normal late in the week an upper ridge builds back into the region. Next chance for rain Fri-Sat.

The upper level flow becomes NW on Monday as a strong upper level trough dives SE from the Great Lakes and pushes off the NE and mid- Atlantic coast Monday night, with an upper level ridge slowly expanding NE from the lower MS Valley. This looks strong enough to drive the sfc cold front well south of the CWA Monday, and bring significantly lower dew points that are more typical of September. The models continue to depict a strong shortwave passing through the region on Monday, so do expect to see a 3-6 hr window where clouds increase and even a few isolated showers develop on Monday before the much drier air surges in from the NNW during the afternoon. Best chance for seeing a few showers with the front will be across the far SE where higher dew pts will linger through the mid aftn hrs. Otherwise, becoming breezy in the immediate wake of the front with significantly drier air and deep mixing aided by the shortwave aloft. With the N-NE win direction, expect to see some gusts to 25-30 mph at the coast in SE VA and NE NC. Highs will be in the low-mid 80s for most.

As high pressure builds in behind the front Monday night, a pleasant night is expected Monday night/Tue AM as winds diminish inland (staying elevated near the coast). Even the NBM now shows lows into the 50s for most areas away from the coast, so expect to see low-mid 50s across most of the piedmont, and 55-60F elsewhere (locally 65-70F at the coast). The upper level ridge becomes nearly stationary across the TN Valley Tue-Wed as a weak upper level trough develops off the SE Coast, with some models placing this feature as far south as Florida. This pattern will allow strong sfc high pressure (~1030 mb), to set up from off the New England coast SW into the Carolina coastal plain through midweek. Highs will stay mostly in the low-mid 80s through Wed with lows in the 50s to lower 60s (locally warmer at the immediate coast). The models now mostly have the upper tough to our S/SE potentially amplifying late in the week which would retrograde the ridge back towards the lower MS Valley. Overall, a decent amount of uncertainty as to how this evolves, but the forecast will continue to show temperatures climbing back to above normal for mid- September, with some low-end rain chances Fri-Sat.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

As of 730 AM EDT Sunday...

Showers have been weakening over the past 1-2 hrs, and will mostly slide off the coast after ~14z. Still periodic IFR-MVFR CIGs early this morning, with a gradual improvement thereafter. Light S-SW winds shift to the W-SW and remain 10 kt or less. All areas should see conditions improve to mainly VFR this aftn, but have included PROB30 groups for aftn SHRA/TSRA at ORF/PHF/ECG (chance is too low at RIC/SBY for now). Drying out this evening and becoming SCT-SKC tonight with light winds.

Outlook: Mainly dry Monday, but as a front drops south through the area, expect elevated N-NE winds (especially at the coast with some gusts to 20-25kt possible). Staying dry Tue- Wed with lighter winds except locally breezy SE VA and NE NC along the coast.

MARINE

As of 125 AM Sunday...

Key Messages:

- Generally benign marine conditions are favored through tonight.

- Small Craft Advisories are possible with increased NE winds behind a front late Monday morning through Monday evening.

A warm front is lifting through the region early this morning. Winds to the south of the front are fairly light with latest obs showing south winds of 5 to 10 knots. Buoy obs show seas of 2-3ft and waves around 1ft. S to SW winds will stay in the 5-10kt range today and 3ft seas will diminish to 2ft. Light winds turn to the west late tonight before a cold front pushes through on Monday.

Guidance continues to trend on the stronger side with that front for Monday, with better post-frontal CAA on NNE winds Monday afternoon and night. Latest local wind probabilities show an uptick for potential sustained winds => 18kt in the Ches Bay, with probabilities now in the 60 to 90% range late Monday morning into early evening. For nearshore coastal waters, high-res guidance shows a 30-50% chance of 25 kt gusts during that same period. Probabilities and the first look at high-res CAM guidance also indicate a brief secondary surge is possible Monday night into Tuesday morning, especially in the lower Bay and lower James River. Increased NE winds favor building seas, likely to ~4ft for most of the coastal zones. 5-6 ft seas remain possible for the southern coastal waters during this timeframe, with those 5-6 ft seas potentially lingering in the 20-60 nm offshore zones from Monday night into mid-week. Onshore winds, mostly 10kt or less, continues Tues through mid to late week as high pressure hangs out to the north.

AKQ WATCHES/WARNINGS/ADVISORIES

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