Marine Weather and Tide Forecast for Tall Timbers, MD

KEY MESSAGES
1) Rain tapers off this afternoon into this evening. Much cooler tonight through early next week. Patchy frost is possible late tonight and again Sunday night in sheltered, rural Piedmont locations.

2) Breezy N to NE winds are expected through early next week, especially along the immediate coast where gusty conditions will persist into midweek. A Wind Advisory remains in effect for Virginia Beach and Currituck County, NC into Sunday morning.

3) Forecast uncertainty remains early next week regarding the track and intensity of the nor'easter offshore. Regardless of model spread, a long-duration coastal flood event is expected.
Coastal Flood Advisories continue for this afternoon's high tide cycle, with Coastal Flood Watches in effect for Monday's high tides across the lower Chesapeake Bay, lower James River, and the Atlantic coast of the Eastern Shore.

DISCUSSION
As of 245 PM EDT Saturday...

KEY MESSAGE 1....Rain tapers off this afternoon into this evening.
Much cooler tonight through early next week. Patchy frost is possible late Sunday night in sheltered, rural Piedmont locations.

Early this afternoon, a seasonally strong cold front pushed offshore of the mid-Atlantic coast. Strong cold air advection in the wake of this front has allowed much cooler air to filter into the region on gusty N winds. Widespread stratiform rain overrunning the boundary has begun clearing across western zones. Expect the remainder of the area to dry out over the next few hours, though clearing will take longer across Southside Hampton Roads into NE NC, where light rain may linger into early evening. Decreasing clouds west of I-95 will allow for late-day sun and modest warming before sunset, though temperatures will generally hold in the mid to upper 50s.

The mid/upper-level trough pushes toward the coast this evening, then closes off offshore tonight as strong 1030+ mb surface high pressure builds in from the northwest. Continued cool/dry air advection will maintain inland clearing, with drying conditions reaching the coast. Overnight lows will drop into the 40s to near 50 along the immediate coast, with upper 30s to lower 40s inland. A well-mixed boundary layer (winds lingering 5-10 mph)
should prevent temperatures from completely bottoming out, therefore minimizing the potential for patchy frost, even across the piedmont. A partly to mostly sunny and breezy Fall day is ahead for tomorrow. Despite plenty of sunshine, highs only in the upper 50s to lower 60s are forecast. As high pressure settles just NNW of the area Sunday night, a better chance for patchy frost arises across the far NW Piedmont, followed by highs in the 60s on Monday.

KEY MESSAGE 2...Breezy N to NE winds are expected through early next week, especially along the immediate coast where gusty conditions will persist into midweek. A Wind Advisory remains in effect for Virginia Beach and Currituck County, NC into Sunday morning.

Low pressure continues to develop along the offshore front near Cape Hatteras this afternoon. The tightening pressure gradient between this developing low and the 1030+ mb high to our northwest will maintain northerly winds of 15 to 20 mph inland, with gusts of 20 to 30 mph. Along the coast, NE winds of 25 to 30 mph with gusts of 40 to 50 mph will continue into Sunday, highest from Virginia Beach south to the NC Northern Outer Banks.

As the cold front shifts farther offshore, confidence continues to increase that the coastal low/nor'easter will deepen further through the first half of next week. The low is forecast to meander offshore of the Carolina/lower mid-Atlantic coast through at least midweek, resulting in persistent breezy conditions inland and prolonged windy conditions along the immediate coast. N-NE gusts will average 20 to 30 mph inland and 30 to 45 mph along the coast, highest over the Virginia Capes south to the NC Northern Outer Banks.

KEY MESSAGE 3...Forecast uncertainty remains early next week regarding the track and intensity of the nor'easter offshore.
Regardless of model spread, a long-duration coastal flood event is expected. Coastal Flood Advisories continue for this afternoon's high tide cycle, with Coastal Flood Watches in effect for Monday's high tides across the lower Chesapeake Bay, lower James River, and the Atlantic coast of the Eastern Shore.

Model guidance exhibits spread regarding cyclone intensity and placement, particularly beyond Tuesday. With the cutoff low detached from the primary jet stream and lacking an upstream kicker trough, probabilistic ensembles favor a system meandering offshore through midweek. Gale-force N-NE winds will drive building tidal anomalies over the next few days, initially generating minor flooding in the lower Bay and lower James River with the upcoming high tide.

Prolonged onshore flow will drive anomalies to 1 to 3 feet above normal astronomical tide. Fortunately, the region is currently in an astronomical neap tide cycle, which will help to mitigate peak water levels. Even so, widespread minor to moderate coastal flooding is expected during high tides through early next week, peaking on Monday. If the low strengthens further or edges closer to the coast, localized major flooding cannot be ruled out, though consensus guidance continues to trend "lower" toward high-end minor to moderate thresholds.
Coastal Flood Watches have been expanded to include the Atlantic side of the Eastern Shore, including Ocean City.

AVIATION /19Z SATURDAY THROUGH THURSDAY/
As of 225 PM EDT Saturday...

Gradually improving flight conditions inland to begin the 18z TAF period, with mainly MVFR CIGs along the coast. CIGs continue to gradually improve late this afternoon and this evening from NW to SE, with all locations returning to VFR by early this evening at the latest.

Winds frequently gust to 30-35 kt at ORF/ECG, and 20-30 kt elsewhere into this evening. Winds diminish slightly inland tonight.

Outlook: Conditions remain VFR for inland sites through Monday.
Continued breezy NNE conditions each day through midweek. Winds gusting to at least 25-35 kt as a nor'easter develops and lingers offshore.

MARINE
As of 330 PM EDT Saturday...

Key Messages:

- Long Duration Gale expected through at least mid week if not beyond as the Nor-easter meanders offshore.

- Brief lull in winds on Sunday as low pressure develops along the front.

- Deterministic and ensemble forecasts suggest the low staying further offshore on Monday, although winds will increase as the low pressure deepens. Still a great amount of uncertainty for mid week as the ensemble guidance ranges from the low gradually moving north and east to the low slightly retrograding to the west leading to a stronger winds in the waters.

Widespread north winds of 25 to 30 kt with gusts to 40 kt across the waters as the surge of cold advection aloft has moved over the area.
These winds should continue through the afternoon and into the evening before gradually starting to decrease overnight. Models have come into better agreement on the lull of winds on Sunday as the low develops a little further south and the ridge builds southward. This could lead to sub gale force gusts extending as far south as Cape Charles Sunday afternoon. However, given the well mixed boundary layer, will continue to forecast gusts to 35 kt except for the far northern coastal zone where gusts will be forecast at 30 kt.

No major changes to the forecast for Monday. With the low pressure now trending further south and offshore, have trended slightly lower with wind speeds and gusts. However, the pressure gradient will tighten across the waters as the low pressure deepens and slowly moves north. The forecast is still above much of the numerical guidance and about the 75th percentile NBM wind. The offshore area will have the best chance to see 34 kt sustained winds, but certainly widespread gale force gusts can be expected in the coastal waters and lower Chesapeake Bay.

Still a great amount of uncertainty for Tuesday and beyond as ensemble guidance shows a diverse set of solutions for the eventual low pressure track. By Wednesday night, the 12z EC ensemble suggests low pressure anywhere from just east of Cape Hatteras to as far as 500 miles offshore. This leads to a very low confidence forecast for Tuesday into Thursday as the winds will be highly dependent on the low pressure track. Regardless of what happens, gale force gusts are expected through Wednesday and the gale warning has been extended until Wed morning.

Hazardous seas will continue through the period. By Monday, expect seas to build to 12 to 18 feet in the coastal waters and remain in that range through much of the week. High surf advisory has been extended into Tuesday.

AKQ WATCHES/WARNINGS/ADVISORIES
MD...Coastal Flood Watch from Monday afternoon through Tuesday morning for MDZ024-025.
High Surf Advisory from 4 AM Sunday to 7 AM EDT Wednesday for MDZ025.
NC...Coastal Flood Watch from Monday afternoon through Tuesday morning for NCZ102.
Wind Advisory until 10 AM EDT Sunday for NCZ017-102.
High Surf Advisory until 7 AM EDT Wednesday for NCZ102.
VA...Coastal Flood Watch from Monday afternoon through Tuesday morning for VAZ097>100-529>531.
High Surf Advisory from 4 AM Sunday to 7 AM EDT Wednesday for VAZ099-100.
Wind Advisory until 10 AM EDT Sunday for VAZ098.
High Surf Advisory until 7 AM EDT Wednesday for VAZ098.
Coastal Flood Watch from Monday afternoon through Tuesday morning for VAZ089-090-524-528.
Coastal Flood Advisory until 6 PM EDT this evening for VAZ097- 098-525-529>531.
MARINE...Gale Warning until 7 AM EDT Sunday for ANZ630-631.
Gale Warning until 7 AM EDT Wednesday for ANZ632>634-639-652- 654-656-658-680-682-684-686-688.
Gale Warning until 7 AM EDT Sunday for ANZ635>637.
Gale Warning until 1 PM EDT Sunday for ANZ650.
Gale Watch from late Sunday night through Tuesday morning for ANZ650.