textproduct: Wakefield

WHAT HAS CHANGED

Small Craft Advisories have been issued for all but the upper rivers Tuesday afternoon/evening into Wednesday.

KEY MESSAGES

1) Heavy rainfall and strong wind gusts are possible this afternoon and evening, mainly near and south of the VA/NC border.

2) Potential for strong to severe storms and flooding will return area-wide on Tuesday and Wednesday ahead of a cold front.

DISCUSSION

As of 340 PM EDT Monday...

KEY MESSAGE 1...Heavy rainfall and strong wind gusts are possible this afternoon and evening, mainly near and south of the VA/NC border.

The surface front remains stalled along the VA/NC border this afternoon. Showers and storms have largely been confined south of the boundary where instability is maximized. The best shear is noted to the north of the front but enough extends southward into NC to allow for a few instances of transient rotation in the storms so far today. However, the main threat from convection today will continue to favor strong winds and locally heavy rainfall. SPC has trimmed the Marginal Risk for severe storms to areas roughly along and S of the US-58 corridor. CAM guidance has been pretty abysmal over the last few days but several models suggest the potential for additional showers/storms into central VA this evening into the overnight as the stalled front finally lifts back to the north. Warm and muggy conditions expected tonight with lows in the low/mid 70s and increase dew points behind the frontal passage.

KEY MESSAGE 2...Potential for strong to severe storms and flooding will return area-wide on Tuesday and Wednesday ahead of a cold front.

Severe potential ramps up considerably on Tuesday as an upper trough amplifies over the Great Lakes. Several shortwaves will traverse the area ahead of the main trough axis. Flow aloft strengthens considerably by the afternoon hours with 40-50 kt of flow noted at 500mb. Low level moisture also ramps up with PWAT values climbing back above 2". Instability is a bit more uncertain with clouds possibly hampering heating to some extent but models still show 2000- 3000 J/kg of MLCAPE across the area. Storm mode is also somewhat uncertain with the potential for a mix of linear segments and semi- discrete cells. All these factors point to a robust severe wx threat across the region. SPC has most of the area in a Slight Risk (level 2/5) with a sliver of Enhanced Risk (lvl 3/5) clipping far northern portions of the MD Eastern Shore. Could see the higher risk area being shifted a bit south and east in subsequent outlooks pending greater clarity on degree of cloud cover and storm morphology. As is typical for Mid-Atlantic July severe setups, the main threat will be from damaging winds but a tornado or two cannot be completely ruled out, especially across the N and NE portions of the region where the shear and low level helicity are progged to be strongest.

The severe threat likely continues into Wednesday, but with the higher probabilities shifted to the south and east ahead of the cold front. How convection evolves on Tuesday will also influence the degree of cloud cover and destabilization potential on Wednesday. That said, the flow aloft is forecast to remain rather strong. SPC has a Slight Risk outlined from Richmond south and east with a Marginal Risk (lvl 1/5) for the remainder of the area.

Despite the ongoing drought conditions, Tuesday and Wednesday both have the potential for localized flooding, especially in urban and poor drainage areas. WPC has most of the area in a Slight Risk ERO on Tuesday and Wednesday with PWAT generally 2-2.25". Decent flow aloft should keep individual cells moving but cell training could result in areas of flash flooding. Some drier air finally moves back into the region Thursday and Friday but some showers and storms will remain possible, mainly across the southern and southeastern portions of the area.

AVIATION /19Z MONDAY THROUGH SATURDAY/

As of 155 PM EDT Monday...

Mix of VFR conditions over the northern half of the area and MVFR CIGs and VSBY from RIC southward. PHF and RIC have observed MVFR HZ associated with some smoke from the Canadian wildfires. Winds are mainly E or SE 5-10 kt this afternoon but will become variable or S overnight as the stalled front lifts back northward. Winds become SW 10-15 with gusts to 20 kt by mid to late morning Tuesday. Some showers and storms are ongoing, mainly near and S of the VA/NC border. These cells will be the most impactful in the ECG vicinity through the afternoon where a TEMPO group has been included. Less confident in seeing convection at RIC, ORF, and PHF so will leave out any specific mention in this forecast. Guidance suggests another area of showers and storms is possible farther north near RIC later tonight but confidence in coverage and timing is low. Regardless, MVFR CIGs are likely at RIC and SBY late tonight with potentially some MVFR VSBY restrictions even outside of precip areas. IFR CIGs are also possible at RIC and SBY toward sunrise but have maintained MVFR for now. Chances for strong storms ramp up quickly late in the period.

Outlook: Rain and storm chances increase Tuesday afternoon and evening with strong storms possible. Additional storms are possible on Wednesday before some drier air moves into the region.

MARINE

As of 340 PM EDT Monday...

- Small Craft Advisories have been issued for late Tuesday into Wednesday for most of the local marine area.

- Strong thunderstorms are possible Tuesday and Wednesday, primarily during the afternoons and evenings.

Weak high pressure is centered off the northern Mid-Atlantic coast this aftn. Meanwhile, a stationary front is located near the VA/NC border. The wind is generally E 10-15kt to the N of the boundary. Seas are 2-3ft, with 1-2ft waves in the Ches. Bay. The bulk of the shower/tstm activity is suppressed S of the local waters this aftn. The front will gradually lift to the N as a warm front tonight with the wind remaining 10-15kt and gradually shifting from SE to S, then SW by Tuesday as the warm front lifts to the N of the local area. The wind steadily builds Tuesday into Wednesday as the pressure gradient tightens in advance of a cold front well to the NW. A SW wind around 15kt is forecast for Tuesday morning, increasing to 20- 25kt with gusts to 30kt Tuesday evening through at least Wednesday morning. Local wind probs for 25kt+ wind gusts peak early Wednesday morning. SCAs have been issued for most of the marine area aside from the upper rivers, beginning late Tuesday aftn/early evening. Seas build to 5-7ft during this time with waves in the bay at 3 to 4ft. Marginal gale conditions are possible for the offshore zone off the Currituck Outer Banks. However, have opted to hold off given that there is little to no probability of sustained 34kt wind (40- 60% of 34kt gusts). Widespread showers and tstms, some of which may be severe, are also expected with the cold front later Tuesday into Wednesday. Conditions improve behind the front Thursday as the wind turns to the N, then NE at 10-15kt.

The rip current risk is moderate for the the northern beaches and low for the southern beaches Tuesday and Wednesday, and likely moderate for all beaches Thursday with the wind turning to the NE.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...None. NC...None. VA...None. MARINE...Small Craft Advisory from 4 PM Tuesday to 1 PM EDT Wednesday for ANZ630>632-634-639. Small Craft Advisory from 7 PM Tuesday to 1 PM EDT Wednesday for ANZ633. Small Craft Advisory from 4 PM Tuesday to 6 PM EDT Wednesday for ANZ650-652. Small Craft Advisory from 7 PM Tuesday to 6 PM EDT Wednesday for ANZ654-656-658.