Marine Weather and Tide Forecast for Washington, DC

NEAR TERM /THROUGH TONIGHT/
Current surface analysis shows a cold front draped across the center of the forecast area, generally along the I-66 corridor.
This boundary can be characterized by a wind shift out of the north to the north of the boundary, as well as much lower RH values and temperatures around 5 to 8 degrees cooler.

Latest thinking still brings this boundary to around the I-64 corridor in central Virginia today before stalling out as it loses energy. Steady lift along this frontal system will keep some threat for showers and perhaps a thunderstorm or two in the picture. As previously mentioned, the air mass to the north will be quite the opposite, being characterized by lower humidity (30 to 35 percent) later this afternoon. Based on observations over the locations well to the north, dew points are much lower across New England and southern Quebec, which is the source region for the airmass advecting into the region.
However, there are no fire weather threats given a lack of substantial gusty winds and recent rainfall, albeit light in terms of amounts.

Today's high temperatures are expected to rise into the upper 70s to mid 80s underneath plenty of sunshine. Despite added cloud cover well south of I-66, the overall air mass is warm to start so it should not take much to push into the 80s. The boundary remains stalled in the vicinity of I-64 into the overnight hours. Some patchy fog is not out of the question over the Potomac Highlands eastward into the central Shenandoah Valley. Most can expect low temperatures in the 50s.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
The aforementioned frontal zone to the south is expected to lift poleward during the second half of Thursday. As this warm front makes its northeastward push, humidity levels will rise as Gulf moisture re-enters the entire area. As this occurs, overall cloud cover will also increase which yields mostly cloudy skies on Thursday. This may offset some of the daytime heating which holds temperatures fairly closer to today/Wednesday. However, ensemble box-and-whisker plots show a bit more spread owing to the uncertainties in the convective forecast. It appears any meaningful activity is tied to the warm front itself. Given the slower and more delayed arrival of this front, a bulk of the shower chances initially focus west of I-95. Some showers may spread eastward into Thursday night which is accompanied by a return to mild nights. Persistent south to southeasterly winds keeps low temperatures in the upper 50s to mid 60s.

Recent forecast packages have noted a slowing trend in the cold frontal passage which was to be on Friday. At this juncture, the Mid-Atlantic remains squarely within the warm/moist sector. A shortwave races toward the east-northeast on Friday morning which likely spreads some morning showers across the area.
However, do expect a break behind this system which will allow temperatures to soar well into the 80s. With forecast 850-mb temperatures around 13-15C, the expected well mixed boundary layer would push highs in the mid 80s. Some spotty upper 80s are certainly possible as well, especially along the I-95 corridor.
Opportunities for showers and thunderstorms increase late in the day as the main trough pivots toward the area from the Upper Great Lakes.

Temperatures remain mild into Friday night, but becoming a bit cooler along the Alleghenies where rain continues. Low temperatures over this mountain range will be in the upper 40s to mid 50s, with upper 50s to mid 60s elsewhere.

LONG TERM /SATURDAY THROUGH TUESDAY/
Cold front and associated wave of low pressure progged to move across FA Saturday. Most guidance has a dry window Saturday morning before the front moves through with rain during the afternoon/evening. Favorable blocking pattern off the coast of the Atlantic makes this front stall near the coast, with the UL system lagging somewhere in the east. Considerable uncertainty and evolution of how this system may cut off into an UL low, and where it may reside if it develops. If it is over the Mid-Atlantic, a couple more days of showery conditions is possible through the early parts of next week. Should the system cutoff to the south or not at all, more quiescent wx is expected.

In terms of temperature, Saturday is likely the warmest day of the long term with 70s for most. Sunday and Monday have more uncertainty as to how much if any precip develops. If rain, cooler and 60s, else 70s. A moderation is likely Tuesday, but how much depends on how quickly any UL system may move out.

AVIATION /14Z WEDNESDAY THROUGH SUNDAY/
Expect a dry forecast through much of the day along with VFR conditions outside of CHO. The early morning cold front eventually stalls in the vicinity of I-64 later today. This sets the focus for some shower activity and perhaps a few rumbles of thunder at CHO. Will maintain a PROB30 group between 18-23Z. Elsewhere, winds should mainly be out of the north to northwesterly direction being north of the boundary.

The system remains stalled to the south through midday Thursday before slowly returning northward as a warm front. This leads to a shift back to south to southeasterly winds, with afternoon gusts up to 15 to 20 knots. Additionally, the return of Gulf moisture and continued warm weather favors some shower and thunderstorm activity. A few restrictions are certainly possible. Winds turn more southwesterly on Friday with sub-VFR conditions possible at times as storms roll through.

MVFR to IFR conditions at all terminals possible with showers and thunderstorms Saturday. VFR conditions returning Saturday night into Sunday, before additional restrictions possible early next week with renewed rain chances. Southerly winds becoming northwest 5 to 15 knots Saturday into Saturday evening.

MARINE
As a cold front continues to slowly push southward today, marine winds shift to northerly today before shifting to a light easterly wind tonight. Winds should stay below SCA thresholds through the first half of Thursday.

The frontal system to the south gradually returns northward as a warm front on Thursday afternoon/evening. Its northward push returns winds to south-southeasterly. Gusts could approach Small Craft Advisory thresholds at times. However, a better chance for such advisories come on Friday ahead of the next cold front.
Additionally, showers and thunderstorms are possible at times both Thursday and Friday.

SCA conditions possible Sat with fropa. Southerly winds become northwesterly behind front. Northerly winds expected Sunday with gusts largely below SCA criteria.

TIDES/COASTAL FLOODING
Given a modest uptick in southerly flow, some of the typically higher guidance (SFAS, CBOFS) approaches minor flood stage at vulnerable sites like Annapolis during the astronomically higher morning tides through today. However, given the brevity of the southerly flow and its relatively low magnitude, feel that flooding seems unlikely at this time.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.