textproduct: Wakefield

WHAT HAS CHANGED

SVR Tstm Watch in effect until 9 PM for all VA-MD zones.

KEY MESSAGES

1) SVR Tstm Watch in effect until 9 PM for VA-MD zones. Marginal SVR risk elsewhere. In addition, locally heavy rainfall will be possible area-wide.

2) Drier weather returns to end the week and likely continues this weekend into early next week.

DISCUSSION

As of 240 PM EDT Wednesday...

KEY MESSAGE 1...SVR Tstm Watch in effect until 9 PM for VA-MD zones. Marginal SVR risk elsewhere. In addition, locally heavy rainfall will be possible area-wide.

Storms have developed across northern VA in advance of a stationary front that will begin to drop S as a cold front late today. The main threat will be from damaging wind gusts. Thus far, the threat for hail is limited as mid level lapse rates are quite weak, however, models do show some potential for these rates to become a bit steeper by late aftn. The Watch extends through 9PM and goes all the way to the VA-NC border. Through 5 PM, the bulk of any SVR activity will be over northern portions of the Watch area, and while southern portions will probably not have much SVR potential, satellite imagery shows some breaks in the clouds moving in from the W that will likely enhance low level lapse rates by late aftn/early evening. Sfc-based and ML CAPE values are already decent, but thus far DCAPE values are quite limited- again this may change as we get to later in the aftn/early evening.

Latest SPC mesoanalysis indicates that the compressed H7-H5 heights is allowing for moderately strong W winds aloft and 0-6km bulk shear to 30- 40kt. Additionally, heavy rain is expected with any storms, and have been seeing instantaneous rates to 5-7"/hr, though the storms are moving so FFWs will be limited to training storms and/or more urban areas in general. Into tonight, some of the CAMs are showing a 2nd batch of additional storms quite late- well after midnight, and this is in association with the trailing upper trough and shortwave energy. Have maintained high chc PoPs for scattered showers/storms to account for this, but this scenario is rather uncertain and the SVR threat would be much more limited as low level lapse rates would be weak given the airmass being worked over considerably. Lows Thu AM will range through the 60s for most.

KEY MESSAGE 2...Drier weather returns to end the week and likely continues this weekend into early next week.

The front gradually pushes south of the area early Thursday as a trough digs out of Eastern Canada into the Northeast CONUS. For Thursday, PoPs will be confined mainly to NE NC, with a slight chc into the piedmont for a few hrs in the aftn (where dew pts stay a little higher in the 60s). Overall though, much drier air will overspread the area with dew pts dropping into the 50s across the I-64 corridor and pts northward. Due to a well mixed BL, forecast high temperatures remain in the low-mid 80s Thursday. Dry and pleasant Thu night with lows mainly in the 50s (60s immediate coast). Friday will be mild and dry as high pressure settles from the Great Lakes to the local area with highs in the upper 70s to around 80 F inland, and in the mid 70s for coastal areas, after a pleasant morning with lows in the mid 50s to lower 60s.

By this weekend, another trough digs out of Canada and pushes another cold front south across the Mid-Atlantic. However, the latest trends are for a stronger northern stream, which suppresses the moisture S. 27/12z EPS/GEFS each depict PW values remaining below normal through the weekend, and even into early next week. For now, NBM PoPs are 20% or less Saturday (mostly likely dry for most locations), with PoPs less than 15% Sunday. NBM PoPs are ~20% Monday/Tuesday, which is near climo. Temperatures will be near to a little below normal overall from Saturday through Tuesday, with highs in the 70s to lower 80s and lows mainly in the 50s, with some upper 40s possible over the Piedmont Sunday morning. Overall, quite pleasant for the end of May into the beginning of June.

AVIATION /19Z WEDNESDAY THROUGH MONDAY/

As of 200 PM EDT Wednesday...

Storms have started to develop well in advance of a frontal boundary N of the region this aftn. Showers/tstms are advancing to the E-SE and will have the potential to affect all of the terminals- generally 20Z-00Z for RIC/SBY, 22Z-02Z ORF/PHF, and 00Z-04Z ECG. Have included TEMPO groups (except at ECG where timing is later have maintained a PROB30). Additional rain chances persist into early Thursday morning, through 04-08Z, but this 2nd batch is more uncertain. Winds will be W-SW at ~10 kt with gusts to 15-20 kt outside of storms this aftn and evening, shifting to the N between 06-12Z. Any showers/tstms have the potential to produce IFR VSBYs in heavy rain along with strong wind gusts.

Outlook: Drier air, N winds, and VFR conditions are expected Thursday through Friday. Another cold front arrives by Saturday, but most guidance depicts this as a dry frontal passage with increased northerly winds and VFR conditions. High pressure and VFR conditions prevail by Sunday.

MARINE

As of 315 PM EDT Wednesday...

Key Messages:

- Thunderstorms will bring strong wind gusts and locally higher waves late this afternoon and evening.

- Winds become northerly behind a front Thursday, followed by light flow Friday. Elevated onshore flow and higher seas possible this weekend as another front moves through the local waters.

The front the brought reduced VIS and some light rain to the northern waters earlier this morning has lifted just north of our area. SW winds prevail this afternoon, with the strongest winds of 10-15 kts with gusts of 15-20 kts are being measured in the lower Bay and the Rivers due to the best mixing occuring on land this afternoon. Winds across the coastal waters are light at ~5 kts in the northern waters, with with the southern waters measuring westerly winds of 10-15 kts. Seas across the coastal waters range between 2-3 ft, and waves in the Bay are measuring 1-2 ft.

While mainly benign conditions are expected, the threat for strong- severe thunderstorms now through this evening today will likely bring significantly higher wind gusts (40+ kt) and locally higher waves. The associated front will drop southward across the area early Thursday, with the wind becoming northerly. While a brief surge in northerly winds is possible along and just behind the front late Thursday morning, conditions should mostly stay sub-SCA. With warmer waters across the Bay, would not be shocked to see a few hours where winds gust to 20 kt around or just after sunrise. High pressure will build in from NW Friday with lighter winds forecast through the first part of Friday night. A stronger system could bring a period of N/NE winds this weekend, with gradually building seas and potential SCAs. There is good model agreement that a surface low will develop over Quebec and drop down across the Northeast and move offshore sometime on Friday night into Saturday. There is some disagreement in timing and magnitude of the winds, so the current wind and wave forecasts are subject to change.

Seas remain in the 2-3 ft range through at least Friday night. Similarly, waves in the Chesapeake Bay will only be in the 1-2 ft range. Building seas are possible later Saturday into Sunday; this is again ultimately dependent on the magnitude of onshore flow and strength of the lows offshore.

AKQ WATCHES/WARNINGS/ADVISORIES

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