Marine Weather and Tide Forecast for Nassawadox, VA

NEAR TERM /THROUGH TONIGHT/
As of 330 AM EDT Tuesday...

Key Messages:

- Showers continue to move into the area with periods of moderate to locally heavy rainfall expected today.

- Flood Watch is now in effect for the majority of the area, excluding the VA/MD Eastern Shore.

- Cannot rule out a few isolated tornado this morning into this afternoon.

Latest analysis reveals a vertically-stacked low pressure over the mid-south early this morning. The attendant surface low has occluded over western TN and will slowly slip north today.
The negatively-tilted upper system and resultant deep-layered SE flow is providing a deep, moist flow of air that has bumped PW values into the 1.5-1.8" range across the region. Numerous spokes of energy embedded within the mid-level flow has allowed for numerous showers already last evening into early this morning, with increased rainfall rates of 1-1.5"/hr producing locally heavy rainfall in spots. The slow-moving upper low and occluded surface low trundles slowly north today, with showers and storms to lift across the region through this evening. While the axis of greatest moisture is progressive, it will nevertheless present a pair of forecasting/sensible wx challenges today and tonight.

Heavy Rainfall...
The heaviest rainfall lifts across much of the region this morning into the afternoon, with the higher rain rates then focusing on the northern neck and eastern shore this afternoon into this evening. Secondary low pressure develops across the Carolina coastal plain this morning, and will lift NE along the sfc warm front later today into this evening. This feature will provide extra forcing for ascent, as well as increasing PWs a bit farther into 1.75-2" range (near daily maxes for both PW and Integrated Vapor Transport). 00z/13 HRRR LPMM still showing a broad swath of 1-3" with locally higher amounts of 4-5+" possible where storms train. Emerging signal from past few runs of CAMs, including the latest 00z/13 run, shows an emerging signal for better chances of training storms occurring along and E of I-95. The PMM max once again shifted east slightly closer to IVT maxima. Given this and the satellite trends, we have expanded the existing Flood Watch NE to include the rest of the VA northern neck, as additional bands of rainfall today into tonight gradually shifting north and east. Flood Watch continues through late tonight.

Tornado Potential...
Apart from the heavy rain potential, forecast soundings show a a rather tropical-like setup with plenty of curvature evident in the lower levels late this morning into the afternoon (0-1km SRH max out around 100 m2/s2). Noted a few rotating storms across eastern NC this morning, and had a few rotating storms across our area yesterday in a far less favorable environment relative to what we should experience later today as convection becomes more widespread. This setup (increased SRH combined with MLCAPE increasing to potentially >1000 J/kg across at least SE portions of the FA) this morning into this afternoon suggest a clear, albeit narrow area of enhanced tornado chances across the coastal plain (along and E of I95), with a broader general straight-line wind threat extending farther inland over the piedmont, where low-level shear is a bit less focused but deep- layer shear is still present. SPC has added a Marginal Risk area for the entire region, with 5% TOR prob oriented along the coastal plain.

Timing...
Mid- and upper-level dryslot begins to integrate into the system from the south this afternoon and tonight. This will serve to diminish areal coverage in showers from SW to NE this afternoon.
However, it will also lead to cooling aloft, steepening lapse rates and increasing instability. The best chance for strong to severe storms looks to be from noon through about 6pm across SE VA/NE NC, as the secondary low lifts into the region along the previously referenced warm front, locally increasing SRH. Highs today in the upper 60s to low 70s.

Tonight...
The upper low will weaken into an open wave off to our W-NW tonight. At the surface, secondary low pressure lifts into the northern mid-Atlantic and a mid-level dry slot lifts farther north into the Delmarva late tonight, allowing showers to taper off from this evening (south) to overnight into Wednesday morning far NE sections. Mild and muggy tonight with low clouds and patchy fog. Lows mainly in the 60s.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
As of 320 AM EDT Tuesday...

Key Messages:

- Lower coverage of storms but remaining unsettled Wednesday.
Afternoon and evening showers and storms are likely, with isolated strong to severe storms possible.

- Trending warmer, with scattered aftn/early evening storms possible Thursday.

The cutoff Gulf low will continue to slowly weaken over the Ohio Valley to begin the day Wednesday. While the best moisture plume lifts well north of the local area, one last wave rounding the base of the upper trough pushes through the region on Wednesday aftn/evening, then sliding offshore Wed night. While we should see some partial clearing and perhaps even some sunshine Wed, expect another round of convection as the upper wave crosses into the region. Given the cooling (steepening lapse rates)
aloft with our proximity to the upper low, aftn convection is a good possibility. A few strong tstms will be possible Wed aftn/evening, but at this time, would expect a loosely-organized and primarily sub-severe storm mode supporting small hail and gusty winds. Relatively weak bulk shear (averaging ~20-25 kt)
should allow for storms to quickly wane with loss of heating, with partial clearing into Thursday. Highs in the upper 70s to lower 80s. Lows upper 50s to low-mid 60s.

Weak upper ridging is expected across the region Thursday, as the next upper low takes shape across the northern Plains/upper midwest. Still enough residual moisture and instability for widely scattered aftn showers/tstms, but overall a much lower coverage is anticipated. Warm with highs into the low-mid 80s.
Mainly dry Thursday night with lows ranging through the 60s.

LONG TERM /FRIDAY THROUGH TUESDAY/
As of 320 AM EDT Tuesday...

Key Messages:

- Summerlike warmth and humidity Friday and Saturday, remaining very warm but with lower humidity Sunday-Monday.

- Isolated to scattered showers/tstms possible Friday- Sunday, mainly dry Monday.

An upper level ridge is forecast to be in place across the area on Friday, shifting offshore by Saturday as the next cold front approaches from the NW. With building heights aloft, and a SW low level flow, highs Friday and Saturday will be well above normal, generally in the upper 80s to lower 90s, along with dew points more typical of summer (upper 60s to lower 70s).
This will lead to heat indices potentially in the mid- upper 90s Friday area-wide. A front looks to approach from the west by later Saturday, with increasing rain chances Saturday afternoon and evening. It will probably be slightly cooler Saturday, though SE VA and NE NC could be just as warm as Friday, with another day where heat indices top out in the mid-upper 90s. Beyond that, there is more uncertainty given only a slight cool down in the wake of the front. The models are into good agreement with an amplified ridge across the central CONUS, and an upper low over the NE CONUS, placing the local area in a NW flow aloft.
PoPs are only ~20% right now but this will need to be monitored for Sunday aftn/evening. Generally looking dry Monday.

AVIATION /19Z TUESDAY THROUGH SUNDAY/
As of 210 PM EDT Tuesday...

Challenging and relatively low confidence CIG forecast through tonight. Broad low pressure over the area has allowed plenty of moisture to move northward and into the area. This has allowed for widespread MVFR and even some IFR conditions across the area, however in general the TAF sites have been mostly MVFR through the day. Heaviest rainfall has generally shifted northward into the eastern shore and northern neck/Middle Peninsula of VA with a widespread overcast. Meanwhile, to the south of the rain the clouds are more broken due to some drying. However, expect clouds and showers to rapidly fill south of I-64 this afternoon due to daytime heating. As such, will maintain a MVFR or IFR forecast for many of this sites this afternoon despite some sites briefly perhaps rising to VFR early in the period. Have introduced a PROB30 TSRA for RIC/ORF/PHF and ECG generally between 21z and 00z as the convection over southern NC associated with an upper disturbance may move into the area.

Overnight, expect the rain to end, but guidance is very bullish on low vsbys overnight due to the heavy rainfall from today and lightening winds. Will therefore keep IFR conditions at all sites overnight into early Wed morning. Conditions will improve on Wed morning due to increased morning mixing.

Outlook: Looking ahead, another round of showers and storms will be possible on Wed afternoon/evening, with a few stronger storms possible. A lower coverage of late day showers/storms is expected Thu-Fri.

MARINE
As of 250 PM EDT Tuesday...

Key Messages:

- SCA conditions persist through into this evening, then winds slowly decrease overnight by Wednesday morning.

- Winds remain sub SCA Wednesday through Friday.

Low pressure will move north across the region late this evening and tonight allowing southeast winds to remain 15 to 25 kt with some gusts to 30 kt or greater. Waves on the Bay are running 3 to 5 ft with ocean seas 4 to 7 feet, highest from Cape Charles south. As the low lifts north winds will decrease from south to north overnight. Winds should drop below SCA conditions at the Port of VA and rivers around midnight and then the Bay by 4 am.
With the pressure gradient persisting longer over the norther waters from Parramore Island to Ocean City, expect SCA conditions with gusty winds to persist in the north until Wednesday morning.

Winds will be sub SCA criteria everywhere later Wednesday morning, however, seas will remain elevated with persistent south winds 5 to 15 kt. Seas remain around 4 to 5 ft into Wednesday afternoon while weaker winds will allow waves of the Bay to drop to 1 to 2 ft. Ocean seas continue to decrease Thursday as winds remain south at 10 to 15 kt.

Southwest winds may increase some Friday afternoon around 10 to 15 kt remaining below SCA. Southwest winds of 10 to 15 kt will persist through the weekend with some afternoon gusts near 20 kt each day. The next weak front may cross the area Sunday with southwest and west winds becoming northwest and north, but likely remaining below SCA criteria.

AKQ WATCHES/WARNINGS/ADVISORIES
MD...None.
NC...Flood Watch until 2 AM EDT Wednesday for NCZ012>014-030>032.
Flood Watch through late tonight for NCZ015>017-102.
VA...Flood Watch until 2 AM EDT Wednesday for VAZ048-060>062- 065>069-079>081-087-088-092-509>511-513>516.
Flood Watch through late tonight for VAZ064-075>078-082>086- 089-090-093-095>098-512-517>525.
MARINE...Small Craft Advisory until 4 AM EDT Wednesday for ANZ630>632- 634.
Small Craft Advisory until 10 PM EDT this evening for ANZ633.
Small Craft Advisory until 1 AM EDT Wednesday for ANZ635>638.
Small Craft Advisory until 7 PM EDT Wednesday for ANZ650-652.
Small Craft Advisory until 4 PM EDT Wednesday for ANZ654.
Small Craft Advisory until 10 AM EDT Wednesday for ANZ656-658.