Marine Weather Net

Tidal Potomac from Key Bridge to Indian Head MD Marine Forecast


OVERNIGHT

S
WINDS
5 KNOTS

MON

S
WINDS
5 - 10
KNOTS

MON NIGHT

S
WINDS
5 - 10
KNOTS

TUE

S
WINDS
5 - 10
KNOTS

The Marine Weather Forecast In Detail:
ANZ535 Forecast Issued: 139 AM EDT Mon Sep 28 2020

SMALL CRAFT ADVISORY IN EFFECT FROM 10 AM EDT THIS MORNING THROUGH THIS AFTERNOON
Overnight...S Winds 5 Kt. Waves Less Than 1 Ft. Patchy Fog. Vsby 1 To 3 Nm.
Mon...S Winds 5 To 10 Kt. Waves 1 Ft. Patchy Fog. Vsby 1 To 3 Nm.
Mon Night...S Winds 5 To 10 Kt. Waves 1 Ft.
Tue...S Winds 5 To 10 Kt. Waves 1 Ft. Showers.
Tue Night...Nw Winds 5 Kt. Waves Less Than 1 Ft. Showers With A Chance Of Tstms.
Wed...Nw Winds 5 Kt. Waves Less Than 1 Ft. A Chance Of Showers.
Wed Night...Nw Winds 5 Kt. Waves Less Than 1 Ft. A Chance Of Showers.
Thu...Nw Winds Around 5 Kt. Waves 1 Ft Or Less. A Chance Of Showers In The Morning.
Fri...Nw Winds Around 5 Kt. Waves 1 Ft. Winds And Waves Higher And Visibilities Lower In And Near Tstms.
SHARE THIS PAGE:           
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
136am EDT Monday September 28 2020

Synopsis
A cold front will move very slowly through the area Tuesday through Wednesday followed by a second reinforcing cold front early Friday. High pressure will build over the region at the end of the week.

Near Term - Through Tonight
A shortwave-trough is moving through the area this morning and responsible for a high dense overcast. This feature is expected to exit the area to the northeast by 15Z today with scattered fair weather cumulus. Shortwave-rdiging and lingering subsidence today should keep things mainly dry except perhaps in the mtns where models show shallow convection possible, not a guarantee, but it's a non-zero chance. Nothing significant will happen tonight other than an increase in cloud cover late tonight primarily low-level clouds as moisture deepens ahead of the approaching cold front.

Short Term - Tuesday Through Wednesday Night
As upper level trough amplifies east of the MS River Tuesday and upper level flow becomes parallel to surface front, surface cold front will slow down with multiple areas of low pressure developing in response to deepening trough and strengthening jet dynamics. Moderate to heavy rainfall is expected mainly in the Tuesday night time frame as areas of low pressure move across the area. Heaviest rainfall is expected mainly east of the Rt 15 corridor where the best instability is forecast. 1-2 inches of rain seem likely east of Rt 15 with potential for 2-4 inches east of I-95.

Conditions will begin to improve gradually from west to east Wed with rain/showers tapering off Wednesday afternoon.

Long Term - Thursday Through Sunday
On the synoptic scale, broad troughing will dominate over the eastern US from Thursday through the weekend. Multiple shortwaves will progress through the longwave trough during this time period, but low-level moisture will be lacking within the post frontal air mass, and none of the disturbances will be overly impressive. As a result, no precipitation is expected outside of a stray afternoon shower on Thursday or Friday in response to daytime heating beneath the upper trough. A mix of sun and clouds is expected each day, with increased cloudiness during the afternoon hours in response to daytime heating and resultant mixing. Temperatures will run below normal for late September/early October. On Thursday, highs will reach into the upper 60s to low 70s. Slightly cooler air will advect in aloft by Friday into the weekend as the main trough axis shifts overhead. This will lead to highs in the 60s (50s in the mountains), and lows in the 40s (low 50s in downtown DC/Baltimore, 30s in the mountains).

Marine
SCA (Small Craft Advisory) conditions possible this afternoon, but not guaranteed. SCA conditions more likely Tuesday night into Thu morning with SMWs possible Tuesday night in heavy showers and t-storms.

Winds may approach SCA (Small Craft Advisory) levels on Thursday in westerly flow behind a departing area of low pressure. Thereafter, sub-SCA (Small Craft Advisory) level winds are expected over the waters.

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.

Saturday morning, technicians from the National Weather Service Radar Operations Center diagnosed a failure in the bull-gear. This will cause a lengthy delay in returning KLWX WSR-88D to service. Staff from the WSR-88D Radar Operations Center, NWS Eastern Region Headquarters, and the Baltimore/Washington Weather Forecast Office (WFO) will meet today Monday, September 28 to determine the next steps. At that time, we will provide you with another update on the repair and expected time to return KLWX to service. At this point, the radar will be out of service for at least another week or two.

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).

Further updates to keep users informed about the situation will be issued as information becomes available. Thank you for your understanding during this extended outage.

NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...None. VA...None. WV...None.
MARINE...
Small Craft Advisory from 10am this morning to 6pm EDT this evening for ANZ530>543.