Marine Weather and Tide Forecast for Sanford, VA

NEAR TERM /UNTIL 6 AM SATURDAY MORNING/
As of 330 PM EDT Friday...

Key Messages:

- A round of strong to severe thunderstorms is possible between 4-9 PM across the entire area. The main threat with this is damaging wind gusts up to 70 mph, with a low-end threat for large hail and/or a brief tornado.

- A second round of storms is possible after 2-3 AM tonight, which could pose a low-end threat for damaging wind gusts. However, this is highly uncertain and depends on the evolution of the initial round of storms.

The flow aloft remains WSW late this morning as upper ridging slowly pushes to our east. A prominent upper low (stacked atop strong sfc low pressure) continues to spin over the Upper Midwest. Still no prominent surface features nearby, with a cold front still well to our NW and high pressure well offshore to our SE. Dry/very war, wx continues with temps around 90F and mid 60s-lower 70s dew pts, but am watching strong to severe tstms across SW Virginia. In addition, a few severe storms have formed near the MD/DE border that are exhibiting supercellular characteristics. The environment is characterized by steep low/mid-level lapse rates, strong instability (2000-3000 J/kg MLCAPE) and 40-50 kt effective shear (mainly speed shear as hodographs are mostly straight). Strong to severe storms may impact the MD Eastern Shore during the next couple of hours.
Otherwise, we're watching the convection in western VA which is expected to reach the Piedmont by 4-5 PM. This is the main area of convection that we'll be watching for potential severe wx. A Severe Thunderstorm Watch has been issued for the entire area until 03z/11 PM to account for the threat.

There are still uncertainties with respect to convective coverage later this aftn/this evening. But consensus (as well as upstream trends) show that at least a broken line of tstms will cross the CWA from west to east between 4 PM and 9 PM. This is also supported by the WoFS This solution is shown by most of the incoming 12z/16 CAMs.
Given the environmental parameters mentioned above (which are much more favorable for severe wx than we typically see in the Mid- Atlantic), the main threat will be for severe wind gusts (potentially to 70 mph). Large hail will also be possible (have seen reports of 1.75" hail just to our north). Can't rule out a brief tornado as well, but a lack of directional shear will mitigate the tornado threat. There will likely be a break in the storms late this evening-early tonight before a second round of storms potentially approaches early Sat AM (after 2-3 AM). However, these will be weakening as they approach but will pose a low-end threat for damaging wind gusts. Also, if the first round comes through as advertised, this will act to stabilize the environment and thus further lessen the threat for additional severe wind early Sat AM.
Have raised PoPs to ~50% through the evening to account for increased confidence in the first round of convection and will maintain chc PoPs later tonight.

The Storm Prediction Center has a Slight Risk (Level 2 out of 5) for the entire area. Lows tonight should be very reminiscent of summer and range from the upper 60s to lower 70s.

SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/
As of 330 PM EDT Friday...

Key Messages:

- Very warm Saturday with a slight chance of thunderstorms across SE VA and NE NC.

- Drying out later Saturday into Sunday behind a cold front.

Another hot day is ahead for Saturday ahead of a cold front as morning convection should dissipate by 6-9 AM. High temperatures in the upper 80s to lower 90s are expected, with the warmest temps across the SE. The main change in the forecast for Saturday is the waning confidence in severe wx (and also convective initiation during the aftn) as winds become west and dew pts fall during the aftn (especially inland). Will keep 20% PoPs across SE VA/NE NC to account for additional tstm development between 2-8 PM. There will still likely be a highly conditional severe threat across the SE given strong sfc heating and still decent shear in place. Of course, confidence is low regarding any sort of convective initiation. Given this, SPC has maintained a Level 1 out of 5 (Marginal) severe weather risk near the coast. The main threat would again be damaging winds, with large hail also possible. With drier air filtering in behind the front Saturday night, expect cooler low temps in the lower to mid 60s.

Still quite warm for Sunday/Monday as only modest cold advection occurs behind the front. Highs in the lower to mid 80s both days, warmest across the S and SE and coolest on the Eastern Shore.
Overnight lows Sun night drop into the 50s inland and lower 60s closer to the coast.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
As of 330 PM EDT Friday...

Key Messages:

- Unsettled weather returns later Tuesday through Thursday.

- Below average temperatures return by late next week and likely last into next weekend.

Unsettled wx returns for the mid to late week period as an upper level low is progged to track from the Midwest to the east coast from Tuesday through Thursday, before slowly exiting to the NE by Friday/Friday night. While the specifics remain unclear with differences among the deterministic guidance, Tuesday night- Wednesday looks like the wettest period, with a drying trend expected by Thu as cooler air filters in from the NW. With the increased precipitation chances, temperatures trend cooler...and likely below seasonal norms...by Wednesday and Thursday. Below normal temperatures remain favored through the end of the week and looking ahead to Memorial Day weekend.

AVIATION /20Z FRIDAY THROUGH WEDNESDAY/
As of 150 PM EDT Friday...

VFR conditions prevail at the terminals this afternoon with SCT cumulus. However, scattered showers/tstms (some strong to severe with brief gusts to 50 kt) across western VA will track toward the area and potentially impact the terminals between 21-02z. Will maintain PROB30 groups at all of the terminals for a 3-4 hour window and will amend as needed if it is clear that a storm is approaching. There will likely be a break in the storms from 02-07z. A complex of storms will form well to our west and weaken as it approaches early Saturday morning. However, this second round of convection may impact the area (especially RIC/SBY) between 07-12z. Will have VCSH for now given low confidence. Additional showers/storms will remain possible into early Saturday morning. Breezy on Sat with W-WSW winds of 10-15 kt with 20-25 kt gusts. Isolated showers and storms are possible near the coast Saturday afternoon, but PoPs are only ~20%.

Outlook...Prevailing VFR conditions are expected over the weekend into early next week.

MARINE
As of 400 PM EDT Friday...

ey Messages...

- Severe storms possible through this evening with wind gusts in excess of 50 kt possible.

- SW winds gusting to 20 to 25 kt in the lower Chesapeake Bay/ York/James Rivers and Currituck Sound on Saturday. A small craft advisory is in effect.

- More tranquil marine weather expected Sunday into early next week.

SW winds mostly 10 kt or less across the waters this afternoon with a weak trough across the waters. The main concern through this evening will be the chances for severe thunderstorms and the potential for severe wind gusts. Currently one storm just north of Ocean City that will likely impact the far northern Coastal Waters near the MD/DE waters for the next few hours. However, latest high resolution forecast guidance suggests that strong to severe storms will impact the waters perhaps as early as 5 to 7 pm over the central Chesapeake Bay and 6 to 9 pm over the remainder of the waters. These storms have the potential for wind gusts in excess of 50 kt and large hail as they move through. Any storm threat should exit by 9 to 10 pm.

The pressure gradient picks up over the waters somewhat on Saturday ahead of the cold front. These southwest winds will become rather gusty over land, however some of these 20kt gusts will likely impact the southern Chesapeake Bay, James/York Rivers and Currituck Sound.
As such, have issued a small craft advisory for these areas on Saturday into Saturday evening. SW winds decrease early Saturday evening as the front pushes through. Behind the front, winds gradually turn west then northwest on Sunday. Low pressure then deepens over the Canadian Maritimes Sun night into Monday which should allow for NW winds to increase to around 15 kt across the waters. May need small craft advisories with this northerly surge but there is still some uncertainty. Winds gradually turn to the east by Tuesday as low pressure develops to the west of the area and a frontal boundary stays south of the region.

HYDROLOGY
As of 300 PM EDT Thursday...

Flood Warnings continue along the James River, at Richmond- Westham, and Richmond Locks have crested, but will remain in minor flood stage through Friday night. See water.noaa.gov for more site- specific information.

AKQ WATCHES/WARNINGS/ADVISORIES
MD...None.
NC...None.
VA...None.
MARINE...Small Craft Advisory from 10 AM to 10 PM EDT Saturday for ANZ632-634-636>638.
Small Craft Advisory from 10 AM to 7 PM EDT Saturday for ANZ633.