textproduct: Wakefield

WHAT HAS CHANGED

Updated full discussion. No major forecast changes.

KEY MESSAGES

1) A more typical summertime pattern prevails Friday with a low chance of afternoon and evening showers and thunderstorms.

2) Shower and thunderstorm chances continue through the weekend with hot and humid weather expected, especially on Saturday. Dry weather and slightly cooler temperatures return early next week.

3) A warming trend is expected by the middle of next week, with more significant heat possible by later in the week. Shower/thunderstorm chances remain very low through Wednesday.

DISCUSSION

As of 325 PM EDT Thursday...

KEY MESSAGE 1...A more typical summertime pattern prevails Friday with a low chance of afternoon and evening showers and thunderstorms.

High pressure is centered immediately offshore this afternoon. Partly to mostly sunny with temperatures in the mid 80s, with upper 70s at the immediate coast due a slight onshore component to the wind. Quasi-zonal flow prevails aloft from the central CONUS to the Mid-Atlantic, with several shortwaves tracking from the High Plains to TN Valley. Mostly clear tonight with seasonal temperatures in the mid 60s to lower 70s.

Hotter and more summerlike (low-mid 90s) on Friday with continued low-level S-SW flow. Heat indices ~100F are possible in SE VA/NE NC, but generally mid/upper 90s for most of the area. However, an approaching shortwave will bring a low chc of showers and tstms to the area during the afternoon and evening. While it is uncertain exactly how convection will evolve, there remains hints that tstms initially develop in 2 areas Friday afternoon: along the higher terrain to our west and to our SW across the central Carolinas. The best storm chances locally will initially be across northern and western portions of the area, with isolated-scattered convection potentially spreading E or SE during the early part of Friday night before diurnal weakening occurs. It is important to note that most areas probably stay dry Fri aftn/evening, especially in SE VA/NE NC. With the heat and humidity, a few stronger tstms capable of producing highly localized damaging wind gusts cannot be ruled out, especially given increasing 500mb flow in advance of a shortwave trough to our NW.

KEY MESSAGE 2...Shower and thunderstorm chances continue through the weekend with hot and humid weather expected, especially on Saturday. Dry weather and slightly cooler temperatures return early next week.

The upper level flow gradually shifts from the W to NW over the weekend as strong ridging builds over the Mississippi River Valley. A series of shortwaves will drag a cold front through the area late Sunday or Sunday night. While there could be an isolated shower or storm closer to the coast Saturday morning- midday, scattered to potentially numerous showers/tstms are expected area-wide from Saturday afternoon through Saturday evening as a slightly stronger shortwave tracks over the area. With decent W-WNW flow aloft, some storm organization will likely occur on Saturday. Convective coverage likely peaks during the 4 PM-9 PM timeframe before gradually weakening Saturday night. Once again, a few stronger tstms will be capable of producing highly localized damaging wind gusts as it will continue to be hot and humid. In fact, 100-105F heat indices are forecast across southern VA/NE NC. The flash flood threat is rather low for most of the area Saturday, but there could be some hydro issues if convection coalesces over urban areas. Convective coverage is expected to be a bit less on Sunday and confined more to southern portions of the FA as the front begins moving through the area and the low-level flow becomes N-NE across northern portions of the FA. Dry and fairly pleasant weather for the end of June is expected on Monday, with temps in the mid-upper 80s and noticeably lower humidity as high pressure builds toward the area from the NNE.

KEY MESSAGE 3...A warming trend is expected by the middle of next week, with more significant heat possible by later in the week. Shower/thunderstorm chances remain very low through Wednesday.

Upper heights gradually rise from Tuesday-Wednesday as the strong ridge builds E from the Mississippi River Valley. This will lead to a warming trend, though storm chances will remain very low with sfc high pressure remaining just offshore and no forcing mechanism for convection. After seasonable temps Tuesday, temps could rise well into the 90s by the middle to latter portion of next week with heat indices climbing above 100F across a decent portion of the area.

AVIATION /19Z THURSDAY THROUGH TUESDAY/

As of 135 PM EDT Thursday...

High pressure was centered immediately offshore as of 18z. VFR conditions are expected to prevail for the 25/18z TAF period. This wind will mainly be SSW 5-10kt inland this aftn, with seabreeze effects shifting the wind to ENE 8-10kt at ORF and SE 8-10kt at ECG. Otherwise, the wind should gradually become SSW less than 10kt at all sites overnight, and then SSW 8-12kt Friday. FEW-SCT CU will linger this aftn, with CI aloft gradually thinning and pushing E. Mainly clear tonight/early Friday.

Outlook: Diurnally driven showers and thunderstorms develop Friday afternoon and evening, with the best chc at RIC/SBY. There is a better chc of showers/tstms on Saturday across the entire area, and low-end shower/storm chances continue on Sunday (mainly S/SE). Prevailing conditions will be VFR outside of sub-VFR conditions in convection. VFR conditions are expected to return by the beginning of next week as a cold front moves south of the forecast area.

MARINE

As of 220 PM EDT Thursday...

Key Messages:

- South to southeast winds in the Chesapeake Bay increase around Small Craft Advisory criteria late this afternoon into late tonight.

- Thereafter, generally quiet marine conditions expected for the weekend, outside of any thunderstorm activity ahead of a cold front on Friday through Saturday night.

Latest analysis reveals 1020+mb surface high pressure has become centered near Bermuda this afternoon. Light SSW winds over the rivers and upper Chesapeake Bay, with afternoon seabreeze now pushing winds SSE in the lower bay and nearshore over the Atlantic coastal waters. Waves 1 ft or less in the Bay, VA tidal rivers and Currituck Sound, and 2-3 ft in the coastal waters, highest offshore of 20nm.

Small Craft Advisory remains in effect for late this afternoon and evening, as the pressure gradient briefly becomes a bit more compressed with low pressure crossing well north of the local waters. While it will be very marginal, will likely see a few hours of SCA-level winds/gusts in the Bay. South winds of 10 to 20 kt will continue into Friday, with the strongest winds remaining over the coastal waters. Winds then veer around to the SW on Saturday 10-15 kt ahead of a cold front that drops south across the waters Saturday night, which turning winds to the NNE post-frontal Sunday into Sunday night. However, CAA will be minimal behind this front, and accordingly expect winds to remain below SCA thresholds at this time. Isolated thunderstorm activity is possible on Friday, with more widespread showers and storms possible Saturday with the frontal passage. Storms on each of these days will likely require MWSs/SMWs issuances as needed.

Seas throughout the weekend generally 1 ft or less in the Bay and 3 feet or less over the coastal waters.

A low rip current risk will likely remain through Saturday, with generally benign conditions currently forecast, the lack of shore-normal flow, and shorter period waves. With flow turning to a more shore-normal orientation Sunday, a Moderate Rip Current Risk has been issued for Eastern Shore beaches Sunday.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Small Craft Advisory until 4 AM EDT Friday for ANZ630>632-634.