textproduct: Wakefield

WHAT HAS CHANGED

- Slight Risk Excessive Rainfall Outlook area has been expanded to include all but far southeast Virginia and northeast North Carolina on Sunday. Slight Risk Severe Weather Outlook now includes all but coastal MD and our NC counties. Increasing chances for showers and storms presenting both a severe and flood risk for late this afternoon and evening

- Probabilities for Heat headlines have largely held steady, but still look likely over our southern tier of counties, including much of Hampton Roads into northeast NC.

KEY MESSAGES

1) Warmer and more humid today with more widespread late day and evening showers and storms expected. Strong to severe storms and localized flash flooding will be possible.

2) Hot and humid with afternoon storms Monday ahead of the next cold front. Heat Advisories are likely to be needed for Hampton Roads into Northeast NC on Monday.

DISCUSSION

As of 250 AM EDT Sunday...

KEY MESSAGE 1...Warmer and more humid today with more widespread late day and evening showers and storms expected. Strong to severe storms and localized flash flooding will be possible.

Another active weather day across the Mid-Atlantic, though model guidance has trended slightly later with storm onset. The expansive upper ridge over the southern tier will slowly dampen today as shortwave energy digs across the Ohio Valley. At the surface, southerly return flow will push the boundary north as a warm front, transporting a tropical airmass (PWATs 2.252.4") back into the region.

Early morning satellite imagery shows an MCV pushing east across SE OH into southwest Pennsylvania/N WV. Good agreement across the past few CAM runs that these showers spread east through sunrise, potentially producing light showers over the VA Piedmont and northern counties by mid-morning, reaching the Eastern Shore by early afternoon. Increased cloud cover and lingering showers will delay diurnal destabilization temporarily. Farther to the SSW, the front is projected to push into the Piedmont toward I-95 this afternoon, with MLCAPE values rising into the 10001500 J/kg range by mid to late afternoon.

Additional spokes of shortwave energy cross the region late today, likely triggering another round of scattered to numerous showers and storms after 45 PM into this evening, with strong to severe storms possible. Deep-layer shear of ~2530 knotsdecent for mid-Augustwill support multicells and bowing line segments capable of producing damaging wind gusts of 5060+ mph. While less likely, all modes of severe weather remain possible, as strong mesoscale convergence along the warm front and DPVA ahead of the approaching shortwave assist in forcing locally stronger updrafts. Additionally, E-SE winds along the warm front and 01 km SRH values of 150200 m/s will maintain potential rotation and an isolated tornado threat. SPC highlights most of our area north of the VA/NC line in a Slight Risk, with a Marginal Risk for coastal Maryland and our North Carolina counties.

Aside from the severe threat, heavy rainfall is a concern as steering flow gradually slows this evening. Slow-moving or back- building storms could result in scattered instances of flash flooding. WPC maintains a Slight Risk ERO covering much of central and eastern VA, mainly north of US-460 and west of the Chesapeake Bay.

KEY MESSAGE 2...Hot and humid with afternoon storms Monday ahead of the next cold front. Heat Advisories are likely to be needed for Hampton Roads into Northeast NC on Monday.

Hot, humid conditions look to peak on Monday ahead of an approaching cold front, with highs reaching the low to mid 90s. High temperatures combined with dewpoints in the mid to upper 70s will yield heat indices of 105+ across southern/southeastern portions of the area and 100105 elsewhere. Heat Advisories will likely be needed for North Carolina counties, Hampton Roads, and possibly even into south-central Virginia. Some scattered showers and storms are also expected Monday afternoon/evening along the lingering frontal boundary. Drier and slightly cooler conditions arrive for Tuesday through midweek.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

As of 250 AM EDT Sunday...

Predominate VFR is persists over most of the TAF sites. A stationary front south of the local area will begin to lift N as a warm front overnight into Sunday. Remnant showers may try to approach far northern/western portions of the area later this morning, but confidence in any direct impacts at the TAF sites remains low. Light E/SE winds have allowed for some patchy ground fog/low stratus, mainly around the KPHF terminal and have allowed for some brief flight restrictions, including some short-lived IFR/LIFR VSBY through 8-9z or so.

More widespread showers/tstms develop this afternoon. This will bring the potential from brief sub- VFR conditions as well as the potential for strong to damaging wind gusts. The wind will primarily be SSE 8-12kt this afternoon outside of any showers/tstms. Have again included PROB30s to account for developing convection late today into tonight.

Outlook: Showers/tstms linger into tonight with localized sub- VFR conditions possible. Unsettled conditions continue on Monday afternoon and evening ahead of an approaching cold front. Mainly dry/VFR conditions return through midweek as high pressure returns.

MARINE

As of 250 AM EDT Sunday...

Key Messages:

- Small Craft Advisories remain in effect for the Chesapeake Bay and coastal waters N of Cape Charles this afternoon into tonight due to increasing southerly winds and building seas.

- Showers and storms are also expected today, some of which could be strong to severe.

Sub-SCA conditions are expected to prevail through midday. Winds are light from the ESE and SE this morning and will become S and increase this afternoon. The pressure gradient is expected to tighten some as a weak front approaches and Small Craft Advisory conditions are expected to develop in the Chesapeake Bay this afternoon and the ocean by the late afternoon/evening hours. Sustained winds will generally be 15-20 kt with gusts up to 25-30 kt (highest N of Cape Charles on the ocean). Seas briefly build to 4-5 ft and will again be highest N of Cape Charles. Waves 3-4 ft on the Ches Bay. Showers/storms could also produce locally higher winds late today. Winds and seas subside by mid-morning Monday. Thereafter, light flow and benign conditions are favored into the middle and end of next week.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 1 PM this afternoon to 7 AM EDT Monday for ANZ630-631. Small Craft Advisory from 4 PM this afternoon to 7 AM EDT Monday for ANZ632-634. Small Craft Advisory from 7 PM this evening to 7 AM EDT Monday for ANZ650-652-654.