Marine Weather and Tide Forecast for Smith Island, MD

KEY MESSAGES
1) Light to moderate morning rain still expected.
There is a Slight Risk (level 2/5) for severe weather with afternoon thunderstorms. A few brief tornadoes and strong wind possible.

2) A brief warmup is expected early next week with cooler temperatures later in the week.

3) Coastal Flood Advisories have been issued for portions of east-central VA along the Bay and tidal Rappahannock/Potomac for minor flooding Sunday. Coastal Flood Statements have been issued for Hampton Roads, the tidal York/James, and the bayside of the lower Maryland and VA eastern shore for nuisance flooding Sunday.

DISCUSSION
As of 305 AM EDT Sunday...

KEY MESSAGE 1...Light to moderate morning rain still expected.
There is a Slight Risk (level 2/5) for severe weather with afternoon thunderstorms. A few brief tornadoes and strong wind possible.

Early morning sfc analysis indicates the remnant sfc low from Isaias and the attending UL low situated over TN and a warm front extending east from it into the Carolinas. This warm front is forecast to lift north into the local FA this morning, then the low will cross from SW VA toward the Eastern Shore during the afternoon. High pressure ridging off the New England coast is ridging down the mountains, forming a subtle CAD feature over the western piedmont and Appalachia. Latest radar shows light to occasionally moderate rain across much of the area and is most widespread around the Richmond metro and the northwestern counties. Winds are gusty at the coast ahead of the aforementioned features with gusts up to 30mph already observed. High-res guidance does still indicate that rain should fill in across the area, becoming moderate to locally heavy at times as the warm front pushes into the area. Once this batch of rain lifts north, there should be a break in the rain for the middle portion of the day. A second round of precip will then cross through the area SW to NE as the low passes through. Total QPF from both rounds of rain looks to be quite a bit lower than was guidance depicted several day ago, partially due to the dry slot that was not originally shown. Based on radar trends so far and latest runs of the HRRR/REFS, total QPF will likely only be 0.5" to 1" at most for much of the area. Areas along the immediate coast in NC/Virginia Beach and far western areas in Louisa/Fluvanna could see closer to 1.5". Probs for 2" have dropped to ~20% for these areas with <10% for the rest of the area.

The second round of rain this afternoon is where the severe weather risk comes in. CAMs depict a broken line and/or supercells progressing from SW to NE during the late afternoon as the sfc low trek NE and the UL trough pivots into the region. A moist and unstable airmass will advect into the area behind the warm front.
00z guidance suggests MLCAPE will climb into the 1000-1200 J/kg range which is more than enough to support convective activity. Deep layer shear of 40kt+ along with low level shear of 30kt+ and long, curved hodographs further supports the threat. Add to that SRH values over 200, low LCLs, and SE sfc winds and you've got yourself a decent set up for a few tornadoes and damaging wind gusts. The SPC outlook for today is mostly unchanged from yesterday with a slight risk for interior portions of the FA and a Marginal Risk along the coast. Highest confidence is south of I-64 since CAD may dampen instability across the north and northwest.

Showers and thunderstorms from this second round should taper off by 8pm. Additional showers on the backside of the low will be possible late tonight into early Monday, primarily north of I-64 and on the Eastern Shore.

KEY MESSAGE 2...A brief warmup is expected early next week with cooler temperatures later in the week.

An upper level ridge centered across the central CONUS gradually builds into the region through the week. Meanwhile, surface high pressure remains centered across the Deep South through midweek before a second area of high pressure builds in from the north late in the week. This will bring a warmup with highs in the 70s for most Mon, lower 80s for most Tue (mid- upper 70s across the Eastern Shore), and mid 80s for most Wed (upper 70s to near 80F for the Eastern Shore). Temps gradually cool late in the week but remain at or above average through Fri. Otherwise, mainly dry conditions are expected from Mon- Thu.

KEY MESSAGE 3...Coastal Flood Advisories continue for portions of east-central VA along the Bay and tidal Rappahannock/Potomac for minor flooding today. Coastal Flood Statements continue for Hampton Roads, the tidal York/James, and the bayside of the lower Maryland and VA eastern shore for nuisance flooding. A high Surf Advisory has been issued for all coastal zone for ~8 ft nearshore waves.

A rapid rise in water levels is expected with the high tide cycle today, occurring mainly in the morning for the lower Chesapeake Bay, lower James, and during the afternoon farther north across the middle Peninsula/northern Neck and late afternoon into early evening for the lower Maryland eastern shore Bay zones. Given the E-SE wind direction, the highest impacts are expected across areas in the Advisory (east central VA along the tidal Rappahannock/Potomac and west shore of the Bay. This should be just one tide cycle with the fast moving nature of this system and winds becoming S-SW later this afternoon and tonight.

AVIATION /12Z SUNDAY THROUGH THURSDAY/
As of 650 AM EDT Sunday...

The 12z/11 TAF period will be unsettled as a warm front lifts across the area this morning and sfc low pressure passes through this afternoon. IFR is spreading across the terminals with MVFR hanging on another hour or two at SBY. Light rain should continue to spread across the FA as well as lowering CIGs as the front presses north. A break in precip is forecast around mid- day, but CIGs are expected to stay in IFR range. A second round of showers and thunderstorms will then pass through the area SW to NE as the sfc low traverses from SW to NE as well. Conditions are expected to improve tonight into Monday morning. ESE winds will be gusty through this afternoon, especially at the coast.
Winds turn to the S then SW this evening.

Outlook: Dry conditions expected after sunrise on Mon. VFR conditions prevail through mid week.

MARINE
As of 325 AM EDT Sunday...

Key Messages:

- Gale Warnings and Small Craft Advisories in effect this morning as the remnants of Isaias track through the TN Valley and towards the local area, with strong high pressure well off the east coast.

- A cold front crosses the waters on Monday with increasing NW winds. SCA conditions are likely in the Chesapeake Bay.

Surface analysis shows Isaias' remnant low over TN with 1032mb high pressure centered east of Cape Cod. A tight pressure gradient is noted across the Mid-Atlantic with easterly winds 20-25 kt with gusts 30-35 kt. Waves in the bay are 2-4 ft with 3-5 ft near the mouth. Seas offshore are building rapidly from S to N. Buoys off the northern OBX are showing 6-9 ft seas with 3-5 ft seas north of of Cape Charles.

Gale Warnings and strong Small Craft Advisories remain in effect for all area waters this morning. Latest guidance and local wind probs have continued to trend downward with respect to both the magnitude and duration of gale conditions ahead of and along a northward lifting warm front this morning. Observations off the NC coast do show some gusts ~35 kt so far this morning and these winds will lift northward into the local coastal waters over the next 6-9 hours.
Gale conditions will to be fairly brief at any particular location, with the strongest winds likely to accompany the lifting warm front's passage. Thereafter, winds will become SE and fall below gale thresholds. SCAs will replace gales from S to N as the strongest winds lift northward through the morning hours. SCA conditions continue in the sound/rivers until early afternoon and in the Ches Bay through early evening, though headlines in the bay could be cancelled prior to expiration with current model trends showing rapidly diminishing winds this afternoon. Waves in the bay will continue to build to 3-5 ft (5-7 ft at the mouth) this morning before falling to 2-3 ft (3-4 ft mouth) this afternoon. 6-9 ft seas nearshore and 7-11 ft well offshore will lift northward with the stronger winds this morning. Have expanded the High Surf Advisory to include all coastal zones given current observations. Seas will slowly diminish this afternoon into tonight but are expected to remain above the 5 ft SCA threshold well into Monday.

A cold front is forecast to cross the waters in the wake of the departing system Monday morning. Another period of SCA conditions is likely for the bay through early afternoon as cooler and drier air filters into the region. Mainly sub-SCA conditions Mon night through midweek. Another front likely crosses the waters late Wed into Thurs with increasing N and NE winds. Long range models are starting to key in on a much stronger frontal passage next weekend.

AKQ WATCHES/WARNINGS/ADVISORIES
MD...High Surf Advisory until 6 PM EDT this evening for MDZ025.
NC...High Surf Advisory until 4 PM EDT this afternoon for NCZ102.
VA...High Surf Advisory until 6 PM EDT this evening for VAZ099-100.
High Surf Advisory until 4 PM EDT this afternoon for VAZ098.
Coastal Flood Advisory from 11 AM this morning to 6 PM EDT this evening for VAZ075>077-521-522.
Coastal Flood Advisory until 4 PM EDT this afternoon for VAZ078-085-086.
MARINE...Small Craft Advisory until 7 PM EDT this evening for ANZ630>632.
Small Craft Advisory until 1 PM EDT this afternoon for ANZ633- 635>637-639.
Gale Warning until noon EDT today for ANZ634-654-656-684-686.
Small Craft Advisory until 7 AM EDT this morning for ANZ650- 652.
Gale Warning until 4 PM EDT this afternoon for ANZ650-652-680- 682.
Gale Warning until 10 AM EDT this morning for ANZ658-688.