Hughesville, MD 20637 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

Made a small expansion to the Dense Fog Advisory to include northern Fauquier, Rappahannock and Warren Counties.

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.

A couple of consecutive days of light onshore flow has increased low-level moisture enough to result in (1) river valley fog west of the Blue Ridge (locally dense at times), and (2) low clouds banking along and east of the Blue Ridge and Catoctin Mountains. Clouds/fog are more expansive relative to Wednesday morning, but should burn off and lift by midday to early afternoon as winds shift from southeast to southwest.

The NAM seems to be handling the low-level moisture profiles best, with low clouds favored east and areas of fog west (as opposed to a lot of other guidance which maintains a dense fog threat to the east with minimal fog to the west).

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

Low clouds (FL020-FL030) will continue to bank up the east side of the Blue Ridge and Catoctin Mountains, expanding across the I-95 corridor through daybreak. Ceilings may gradually lower, possibly breaching IFR 11Z-13Z, though given recent trends MVFR is more favored. Low clouds are beginning to show a slow eastward shift due to south to southwest flow. To the west at MRB, fog is developing nearby, and may still become dense at times until about 13Z. Light SE flow early this morning becomes SW today through tonight with VFR expected to return 15Z-18Z. 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: Dense Fog Advisory until 10 AM EDT this morning for MDZ501-502. VA: Dense Fog Advisory until 10 AM EDT this morning for VAZ027-029- 030-040-501. WV: Dense Fog Advisory until 10 AM EDT this morning for WVZ050-055- 502-504. MARINE: None.