Marine Weather Net

Tidal Potomac from Cobb Island MD to Smith Point VA Marine Forecast


OVERNIGHT

SW
WINDS
5 KNOTS

FRI

S
WINDS
5 KNOTS

FRI NIGHT

SE
WINDS
5 - 10
KNOTS

SAT

SE
WINDS
5 - 10
KNOTS

The Marine Weather Forecast In Detail:
ANZ537 Forecast Issued: 202 AM EDT Fri Sep 25 2020

Overnight...Sw Winds 5 Kt. Waves Less Than 1 Ft.
Fri...S Winds 5 Kt. Waves Less Than 1 Ft. A Chance Of Showers.
Fri Night...Se Winds 5 To 10 Kt. Waves 1 Ft. A Chance Of Showers.
Sat...Se Winds 5 To 10 Kt. Waves 1 Ft. A Chance Of Showers.
Sat Night...S Winds 5 To 10 Kt. Waves 1 Ft.
Sun...S Winds 5 To 10 Kt. Waves 1 Ft Or Less.
Sun Night...S Winds 5 To 10 Kt. Waves 1 Ft.
Mon...Sw Winds 10 Kt. Waves 1 Ft. A Chance Of Showers.
Tue...S Winds 10 To 15 Kt. Waves 1 To 2 Ft. A Chance Of Showers.
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Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
858pm EDT Thu September 24 2020

Synopsis
High pressure centered over the western Atlantic will promote a return flow over the region as the remnants of Beta cross into the Carolinas while weakening Friday into Saturday. High pressure will remain in control for the latter half of the weekend before a cold front drops southeastward from the Great Lakes early next week.

Near Term - Until 6am Friday Morning
High pressure will remain offshore tonight while the remnants of Beta track through the Tennessee Valley. Plenty of high and mid-level clouds will continue to pass through the area tonight, but the remnants of Beta should remain far enough to the south for dry conditions.

Areas of fog and low clouds are possible overnight due to more low-level moisture compared to recent nights, light winds, and the fact that the high and mid-level cloud deck is thin. Locally dense fog is possible. Will have to monitor observations overnight to see if a Dense Fog Advisory is warranted.

The clouds along with a weak warm air advection regime will result in slightly above normal temps, with 50s to near 60 degrees expected.

Short Term - 6am Friday Morning Through Saturday Night
Latest guidance favors keeping the heaviest precipitation associated with the remnants of Beta to our south, mainly across extreme southern Virginia and the Carolinas Friday into Friday night. That being said, am carrying middle of the road chance POPs south of the District Friday afternoon and evening, with central Virginia carrying the highest chances and Quantitative Precipitation Forecast potential once again. Ample cloud cover will keep temperatures in the upper 60s to near 70 degrees over our southern zones, with low to middle 70s further north where slight rain chances exist.

The primary upper trough axis crosses the area Friday night, so will maintain chance POPs into Saturday morning for areas east of the Blue Ridge and over the Chesapeake Bay. Slightly above normal temperatures will persist through Friday night.

Lingering showers will be possible Saturday morning over the eastern half of the CWA as the upper trough exits to our east, however a light onshore flow may aid in keeping clouds around through a good portion of the day before some clearing commences. High pressure will nudge back overhead Saturday night as an upper ridge builds overhead. Near to slightly above normal temperatures expected Saturday and Saturday night as dewpoints elevate into the 60s. With increasing low level moisture, patchy fog will be possible Saturday night as well.

Long Term - Sunday Through Thursday
Global models show a split jet configuration with a residual southern stream impulse ejecting out of the Ozarks early Sunday. This will likely shear on its northeastward progress into the Mid- Atlantic during the overnight hours. Within the northern branch of the jet, synoptic flow is forecast to be amplified and progressive. A fairly potent jet streak will likely accompany these height falls with an array of solutions noted in the guidance. While the core of lower heigheights remain along the Ontario/Great Lakes border, some of the global models show an embedded impulse which may attain a negative tilt on its pursuit toward the Eastern Seaboard. Forecast solutions are quite variable in terms of placement, magnitude, and timing. Thus, confidence is low at this juncture, but showers and thunderstorms are likely early next week. Eventually a cold frontal passage will ensue ushering in cooler, drier air as cyclonic flow sets up across the northeastern quadrant of the U.S. by mid-week.

To conclude the weekend, warm and humid conditions will prevail as southwesterly flow steers Gulf moisture up the East Coast. Sunday's dew point temperatures are forecast to reach the upper 60s accompanied by highs in the low 80s. While pre-frontal, Monday could cool down a bit given the increase in cloud cover from warm advection processes. Even upon cold frontal passage, initial cooling will be stunted given well-mixed downsloping flow. Eventually highs around 70 degrees are possible by mid-week although quite a bit of spread is noted in the ensemble spread plots.

Marine
High pressure off the coast will promote a light southerly flow over the waters through Saturday as the remnants of Beta track to our south and weaken in the process. Given a weak gradient over the area during this time, sub SCA (Small Craft Advisory) conditions are expected through Saturday night.

Breezy southerly winds on Sunday and Monday could lead to Small Craft Advisory issuances. Additionally, there will be the chance for locally gusty winds from any developing showers and thunderstorms on Monday. Small Craft Advisories are possible into the middle of next week.

Tides / Coastal Flooding
Minor tidal flooding will remain possible with the high tide cycle late this evening into the overnight, especially around Washington DC and Annapolis. However, anomalies have fallen some this evening due to light winds. Therefore, confidence is too low for any advisories at this time.

Equipment
The KLWX (Sterling, VA) WSR-88D remains out of service until further notice. The outage is due to a failure within the Radar Data Acquisition Functional Area that occurred early in the morning on September 20, 2020.

Technicians from the National Weather Service Radar Operations Center will arrive in Sterling on Saturday, September 26, to diagnose the failure. At that time, they will determine the full scope of the failure, and work with WFO Sterling electronics program staff in taking subsequent maintenance actions. Action and diagnosis includes repairing the gear box and assessing the health of the bull- gear.

Users of KLWX can utilize adjacent weather radars located in Dover DE (KDOX), Mt. Holly NJ (KDIX), Pittsburgh PA (KPBZ), Charleston WV (KRLX), Blacksburg VA (KFCX), and Wakefield VA
(KAKQ).

NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...None. VA...None. WV...None. MARINE...None.