Columbia, MD 21045 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: Tonight

No hazardous weather is expected at this time.

Days two through seven: Thursday through Tuesday

No hazardous weather is expected at this time.

Spotter information statement

Spotter activation is not expected at this time.

What has changed

A Coastal Flood Advisory has been issued for Anne Arundel until 11PM EDT tonight. Fog & visibilities were modified to reflect denser conditions along and east of I-95 on Thursday morning. Increased wind gusts for Friday afternoon in the wake of the cold front. Lowered dewpoints slightly for Saturday, with some mountain regions potentially seeing RH's in the low 30s. &&

Key messages

- 1) Cloudy the rest of the day, with areas of fog on Thursday morning.

- 2) Above normal temperatures through the end of the week, with increasing clouds heading into the weekend.

- 3) On-and-off rain showers possible Sunday night through Tuesday.

Discussion

KEY MESSAGE 1: Cloudy the rest of the day, with areas of fog on Thursday morning.

A weak shortwave disturbance brings intermittent overcast skies to the Mid-Atlantic today, with increased low-level moisture lending to a brief period of morning fog and low clouds on Thursday morning. Warm advection persists through the afternoon as a weak warm front lifts north along with persistent onshore flow. This will allow for an increase in dewpoints/moisture on Thursday, before the disturbance gradually transitions offshore by Friday morning.

Combined with overall light winds, areas of fog could settle in by early Thursday morning, with some areas seeing reduced visibility below 5 miles at times. Fog will likely be concentrated along and east of the I-95 corridor through 14Z, with areas further west likely seeing overall patchier fog. As the shortwave disturbance transitions offshore, clouds clear in the afternoon, with warm afternoon temperatures ranging in the low-to-mid 70s.

KEY MESSAGE 2: Above normal temperatures through the end of the week, with increasing clouds heading into the weekend.

As the midweek shortwave disturbance transitions offshore, another brief period of upper-level ridging builds over the Mid- Atlantic between Thursday afternoon and Friday. Winds could gust up to 15-20 knots throughout the day on Friday as temperatures range well above average with afternoon highs in the mid-70s.

An incoming cold front could bring overnight temperatures back down into the 40s between Friday & Saturday across the metros, with temps potentially in the upper 30s over the mountains. Saturday will see increasing cloud cover throughout the day as this front moves through the region, bringing temperatures back down to more seasonable daytime ranges in the 60s. No precipitation is anticipated for most of the weekend as this front slowly begins to track through into early next week.

KEY MESSAGE 3: On-and-off rain showers possible Sunday night through Tuesday.

High pressure should keep most, if not all, of the region dry through the heart of the day Sunday. Rain chances could arrive with an approaching low pressure system Sunday night and linger through Tuesday. It is too early to tell how much in coverage these showers will be each period, but some areas may not see any showers at all. All in all, rain amounts could be light. Temperatures will be seasonable Sunday, but then inch their way upwards Monday and Tuesday as a southerly to southwesterly wind brings in slightly milder air. Highs Sunday in the middle 60s for most locations, then climb into the upper 60s to near 70 for both Monday and Tuesday.

Aviation

Conditions have generally returned to VFR this afternoon, with a shortwave disturbance bringing a few cloud decks to the Mid-Atlantic this afternoon as it heads towards the coast. Additional low clouds and fog could develop early Thursday morning, with higher potential reaching along and east of the I-95 corridor. There is still some uncertainty as to where exactly the low clouds develop, so some TAF sites show borderline IFR/MVFR conditions between 0800Z-1400Z Thursday depending on this uncertainty. Fog could occasionally bring visibilities to 1-2SM during this time.

Visibilities return to VFR between 14Z-16Z Thursday, with clouds generally clearing by the afternoon. Winds flow southerly Thursday before shifting northwesterly on Friday, with gusts potentially up to 15-20 knots throughout the day. Winds diminish on Saturday before shifting southerly again.

VFR conditions Sunday through Monday night. Light southerly winds around 5 knots or so Sunday, becoming light and variable southeast to northeast Monday and Tuesday.

Marine

Light southeasterly winds through this evening, then shifting southerly overnight. Winds strengthen to borderline SCA thresholds Friday & Saturday due to increased vertical mixing over near- shore/narrower waterways, shifting northwesterly by Friday evening. Winds diminish by Saturday evening. Up until Friday morning, winds stay within 5-10 knots.

No marine hazards expected Sunday through Monday night. Winds south 5 to 10 knots Sunday, becoming east to northeast 5 to 10 knots Monday and Tuesday.

Tides/coastal flooding

Onshore flow Thursday & Friday could push sensitive shorelines close to flood stage, primarily during the evening tide cycles. A Coastal Flood Advisory has been issued until 11PM this evening for Annapolis in anticipation of minor flooding that could occur with the high tide.

Light offshore flow should lower tidal anomalies on Saturday before winds shift again on Sunday.

Watches, warnings and advisories

DC: None. MD: Coastal Flood Advisory until 11 PM EDT this evening for MDZ014. VA: None. WV: None. MARINE: None.