Washington, DC 20565 Weather

This Hazardous Weather Outlook is for the Maryland portion of the Chesapeake Bay, Tidal Potomac River, and I-95 corridor through central Maryland, northern Virginia, and District of Columbia.

Day one: Today and Tonight

No hazardous weather is expected at this time.

Days two through seven: Friday through Wednesday

No hazardous weather is expected at this time.

Spotter information statement

Spotter activation is not expected at this time.

What has changed

Dense Fog Advisory will expire at 10 AM as fog is quickly dissipating.

Key messages

- 1) Above normal temperatures through Friday, then seasonable with increasing clouds this weekend.

- 2) Rain chances remain uncertain for the first half of next week.

Discussion

KEY MESSAGE 1: Above normal temperatures through Friday, then seasonable with increasing clouds this weekend.

The Dense Fog Advisory in effect for parts of the Shenandoah Valley and Potomac Highlands this morning will be allowed to expire at 10AM. The increasing daytime heating is causing fog to dissipate, though some patchy valley fog will linger west of I-81 as fog lifts to stratus, then burns off by around noon.

After the clouds break, mixing on these light southwest winds should allow temperatures to reach into the lower to middle 70s (60s mountains). Low temperatures tonight will be seasonable in the 40s to lower 50s, but may be rather variable over short distances depending on where goes calm and where holds onto a light southwest wind. Higher elevations will actually hold on to more southwest breezes and be poking up into the warming airmass, and could therefore be some of the warmest spots tonight.

Well above normal temperatures persist Friday, despite a cold front crossing the region. Cold air advection lags behind this front, and downsloping flow likely allows for highs to push well into the 70s (60s mountains). One caveat is if some stratocumulus develops on northwest flow, but the background airmass is rather dry so the chance of that happening and it having a significant impact on temperatures is limited.

Eventually, some cooler temperatures will filter into the region Friday night through the weekend. Expect seasonable and dry conditions as high pressure holds firm, with any precipitation becoming less likely through at least Sunday evening.

KEY MESSAGE 2: Rain chances remain uncertain for the first half of next week.

Strong high pressure will remain overhead Sunday and only gradually drift eastward through the first half of next week. The Mid-Atlantic will be caught in between more prominent but slow moving troughs (or closed lows) near Florida/the Bahamas, the Plains, and eastern Canada. Some models still show potential for a shortwave trough to ride around the departing ridge, but at this point the chance for rain has dropped to 30 percent or less between Sunday night and Tuesday night. Even though conditions may largely remain dry, expect more cloud cover between onshore surface flow and a warm advection pattern aloft. Temperatures will likely remain a little above normal through this period despite the extra clouds. The Plains trough may eventually increase rain chances Wednesday or Thursday as it moves eastward, but its progression is uncertain as well.

Aviation

Most of the low clouds and fog have burned off, and should be completely dissipated by 16Z. Light southwest winds through tonight with VFR expected. Low cloud/fog potential appears lower tonight given a persistent albeit light SW wind.

VFR is likely Friday as winds shift to the northwest. Gusts of 20-25 knots are likely around midday into mid afternoon as a dry cold front crosses. Winds become lighter Friday night into Saturday while shifting to the north, with light east to calm winds Saturday night as high pressure builds.

Significant weather is unlikely Sunday and Monday as high pressure moves eastward. However, some low chances of sub-VFR ceilings and a few rain showers exist Monday depending on how the weather pattern evolves.

Marine

Light south to southwest winds are expected through tonight, though a few gusts around 15 knots are possible at times. A dry cold front will shift winds to the northwest Friday, with near shore and narrower waterways having the potential to see gusts to near 20 knots at times. Northerly channeling Friday night may prompt Small Craft Advisories before diminishing Saturday. Winds then shift to the east Saturday night as high pressure builds.

Light winds will likely continue Sunday and Monday as high pressure gradually moves offshore.

Tides/coastal flooding

Tidal anomalies remain elevated, though have been slowly decreasing so far tonight. Some fluctuation is possible over the next 12-24 hours which could send vulnerable shoreline to near minor flood stage this evening.

Offshore flow decreases tide levels Friday into Saturday. Winds turn back around out of the south at low speeds which could cause a modest rebound in tides by Sunday.

Watches, warnings and advisories

DC: None. MD: None. VA: None. WV: None. MARINE: None.