textproduct: Wakefield

WHAT HAS CHANGED

Severe Thunderstorm Watch has been issued for the majority of the CWA.

Strong to severe storms and very localized Flash Flooding is is possible across portions of SE VA and NE NC tomorrow.

Active weather pattern continues Monday through Thursday of next week.

KEY MESSAGES

1) Strong to severe thunderstorms are possible this afternoon as a hot and humid environment is in place.

2) Another round of showers and thunderstorms are possible tomorrow.

3) Seasonable temperatures continue through much of the work week with daily chances of showers and thunderstorms with the potential with cooler temperatures by the end of the week.

DISCUSSION

As of 348 PM EDT Saturday...

KEY MESSAGE 1...Strong to severe thunderstorms are possible this afternoon as a hot and humid environment is in place.

Afternoon weather analysis shows multiple 700mb shortwaves moving across the area which is helping to initiate storms ahead and along a Lee trough which is located along the spine of the Blue Ridge mountains. These showers and thunderstorms are moving into a rich and unstable environment with DCAPE values around 1000- 1300J/kg and MLCAPE values of 2500-3500J/kg. However, shear remains weak with only 25-35kt of bulk shear present with the highest shear concentrated across the MD Eastern Shore. Nevertheless, the atmosphere which is present will allow for multi-cell and broken- line segments to persist across VA and portions of NC potentially produce strong to severe wind gusts and small to severe hail. Will mention, across the MD Eastern Shore where the better shear is overlapping with modest instability a brief tornado cannot be ruled out especially since the environment is sufficient for supercells. With all these ingredients in place a Severe Thunderstorm Watch has been issued for the majority of the CWA. Latest model guidance continues to have these storms persisting through the afternoon and evening as the ongoing environment remains in place. By this evening the severe threat will wind down as daytime heating is lost and a CAP build back in place. The only way for storms to thrive is if they have matured and are able to maintain themselves through the capping inversion. The overall severe threat should end by late tonight into early Monday morning.

As for temperatures, as mentioned earlier a hot and humid environment is in place with temperatures in the low to middle 90s across the area and dew points hovering in the middle to upper 70s. This has allowed for heat indices to between 105-110 along and east of I-95 and 100-105 west of I-95. The Heat Advisory will remain in place through 8pm this evening. For tonight, temperatures will lower into the middle to upper 709s across the area. However, will mention some areas could potentially be in the low 70s if they receive any rain from the thunderstorms this afternoon.

KEY MESSAGE 2...Storm chances return this weekend, bringing the potential for strong, damaging winds and locally heavy rain.

The upper trough will continue to push south into the area for tomorrow. At the surface, a cold front associated with a low pressure system north of the area will advance south and stall somewhere across our area of the area. Model guidance continues to favor the better hot and humid airmass remaining along and south of I-64 for Sunday. Temperatures are progged to be in the upper 80s to low 90s and dews reaching into the low to middle 70s. Heat Incises are expected to be highest south of I-64 with Heat Index values to be between 100-104 and remaining just remaining below Heat Advisory criteria.

In addition, showers and thunderstorms are expected to develop associated with the front as multiple 700mb shortwaves will move across the area. As noted earlier a hot and unstable environment will be in place with MLcape values between 2000-2500J/kg. Again shear will remain weak with bulk-shear between 25-35kt just sufficient enough to help maintain storms. The primary mode will be Multi-cell to small broken line segments potentially producing strong to severe wind gusts. Will also note, there is the potential for localized Flash Flooding as storms are expected to train over the same area multiple times. Latest 12z HREF shows the greatest threat for localized Flash Flooding being located across NE NC.

KEY MESSAGE 3... Seasonable temperatures continue through much of the work week with daily chances of showers and thunderstorms with the potential with cooler temperatures by the end of the week.

The aforementioned cold front will liner across the area Monday bringing another chance of showers and thunderstorms. These thunderstorms could potentially pose the risk of a strong to damaging wind gust and localized Flash Flooding cannot be ruled out especially if storms move over areas that have been saturated from the previous days. Temperatures Tuesday are expected to be around seasonable with highs in the middle to upper 80s. For Tuesday and Wednesday, the severe threat looks to be increasing as a much stronger trough will start to move out of the Midwest and into the Mid-Atlantic. Tuesday looks to be the weakest day as shear remains weak but multiple shortwaves will move through and could initiate storms along the Lee Trough. Wednesday looks the best for severe weather as the better shear moves into place and the trough takes on a slightly negative tilt. At the surface, a strong cold front will move into place Wednesday helping to initiate thunderstorms. The primary hazard at this time looks to be strong to severe wind gusts. Once this front moves through, slightly cooler temperatures are possible.

AVIATION /19Z SATURDAY THROUGH THURSDAY/

As of 121 PM EDT Saturday...

VFR conditions have returned to the terminals early this afternoon. There continues to remain some HZ at RIC but it should clear within the next hour. Partly cloudy conditions are expected as cumulus develop across the area. Winds remain out of the S/SW and and are between 10-15KT with gusts to 20-25KT through the afternoon. Thunderstorm chances return this afternoon/evening, confidence in TSRA has increased and PROB30S been added to all terminals except ECG where thunderstorm chances remain low. Gusty, erratic winds and VIS reductions due to +RA will be possible in these TSRA. SW winds will subside overnight, except for some lingering gustiness along the coast. By tonight, the showers and storm coverage will decrease and VFR conditions will prevail till around 6z where models hint on some MVFR VIS and CIG restrictions across the terminals.

Outlook: Showers/storms are expected to redevelop again Sunday, with additional flight restrictions possible. Rain chances continue into early next week.

MARINE

As of 210 PM EDT Saturday...

- Small Craft Advisory conditions are expected with south/southwest winds this afternoon into Sunday morning ahead of the next front.

- Strong storms are possible this evening and again on Sunday ahead of the front with locally hazardous winds/waves/seas.

Afternoon analysis shows low pressure near the Great Lakes with an associated cold front extending to the SW across the Midwestern states. Winds locally are from the SW 15-20 kt with gusts to 25 kt in the Ches Bay but remain S and a bit lighter (for now) over the ocean. Waves are around 2 ft with seas 2-3 ft.

The gradient is forecast to tighten further later this afternoon and especially tonight ahead of the front. SW winds will stay in the 15- 20 kt with gusts to 25 kt range for the Chesapeake Bay/lower James/Currituck Sound and 20-25 kt and gusts up to 30 kt offshore. SCA headlines have been adjusted a bit with respect to timing based on the latest guidance. All SCA headlines now come to an end at 11z/7AM EDT Sunday. The middle and northern bay zones may be able to be dropped a bit earlier but will leave that decision to subsequent shifts. Waves build to 2-4 ft in the stronger SW flow this evening and tonight while seas increase to 3-5 ft N and 2-4 ft S. The southern ocean advisories may also fall below SCA criteria as the winds decrease early Sunday as seas are not forecast to reach 5 ft in these areas. The surface cold front crosses the waters on Sunday with little to wind enhancement as flow turns to the N behind the boundary.

Showers and storms are possible this evening and into the early overnight hours. Additional storms are possible on Sunday along and ahead of the surface cold front. The storms on Sunday are expected to mainly impact the southern half of the area. Strong winds and locally higher waves/seas can be expected to accompany the stronger convective cells.

AKQ WATCHES/WARNINGS/ADVISORIES

MD...Heat Advisory until 8 PM EDT this evening for MDZ021>024. NC...Heat Advisory until 8 PM EDT this evening for NCZ012>017- 030>032-102. VA...Heat Advisory until 8 PM EDT this evening for VAZ064-075>090- 092-097>100-511>525-528>531. MARINE...Small Craft Advisory until 7 AM EDT Sunday for ANZ630>634-639- 650-652. Small Craft Advisory until 7 AM EDT Sunday for ANZ654-656-658.