Marine Weather and Tide Forecast for North Chevy Chase, MD

NEAR TERM /THROUGH TONIGHT/
Thunderstorm chances increase today as a cold front approaches from the northwest, creating synoptic level forcing. A warm and humid airmass yields plenty of instability with 2000-3000 J/kg of SBCAPE.
Storms will be more progressive in nature compared to previous days and will be slightly more organized with around 15-20 knots of shear. Primary hazards expected with convection today will be damaging winds gusts with saturated model soundings indicating a threat for wet downbursts.

In addition to the severe weather threat, a saturated airmass indicated by model guidance showing PWATS exceeding 2" will lead to a risk of Flash Flooding across much of the area. A Flood Watch has been issued for counties along and east of the I-81 corridor. Within convection, heavy rainfall is expected with precipitation totals of 1-3" possible. Locally higher amounts are possible within strong storms. Rainfall rates up to 2" per hour are possible which may lead to scattered instances of flash flooding.

High temperatures will be in the 80s for most with isolated areas reaching the low 90s. Warm dew point temperatures will lead to heat indices rising into the upper 90s for the area. Overnight low temperatures will be in the 60s to 70s.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/
A frontal boundary stalled over the region will continue daily shower and thunderstorm chances Tuesday and Wednesday. A lack of forcing will limit thunderstorm coverage each day with precipitation chances highest in the southern portions of the forecast area on Tuesday. On Wednesday, shower and thunderstorm chances are greatest in the afternoon during peak daytime heating. Coverage will be more widespread on Wednesday as the stalled front lifts northward.

High temperatures will be in the 80s for most Tuesday and Wednesday.
Highest ridgetops will stay in the 70s while isolated locations in the valleys and southern portions of the forecast area reach the 90s. Overnight low temperatures will be in the 60s for most west of the Blue Ridge and in the low 70s along and east of the Blue Ridge.

LONG TERM /THURSDAY THROUGH SUNDAY/
While we can't guarantee a dry day or period of time in the extended forecast, there does appear to be a lull in the shower and thunderstorm activity across the eastern two-thirds of the region on Thursday. Most shower and thunderstorm activity should occur in the western third Thursday afternoon and evening due to a trough of low pressure nearby. Some of this activity could spread farther east Thursday evening, but confidence is low. High temperatures should be in the lower to middle 90s.

By Friday, the possibility of lull in convection could go away as a cool front pushes southeast across the region Friday midday through Friday evening. The front could spawn shower and thunderstorm activity across all parts of the region. High temperatures again should reach the lower 90s.

A couple of showers and a thunderstorm could linger or pop up on Saturday with the heating of the day, but a weak area of high pressure could win out and push into the region from the northwest.
This high would bring a break in convection once again with a drying northwest to north wind. Humidity may not drop too far but there may be just enough dry air moving in the lower levels to restrict convection much of the day Saturday. High temperatures should reach the middle to upper 80s.

Dry conditions could linger through the day Sunday with high pressure still holding on. A slight upslope component to the wind in the mountains in the west could spawn a few showers. Overall, conditions should still be tranquil in most areas. Highs in the middle to upper 80s again.

AVIATION /07Z MONDAY THROUGH FRIDAY/
Showers and thunderstorms will likely impact the terminals today as a cold front approaches from the west. Within showers and thunderstorms, gusty winds, frequent lightning, and flight restrictions are expected. Winds remain out of the south/southeast today, blowing 5 to 10 knots in the afternoon and becoming light and variable overnight.

A cold front stalls nearby Tuesday and Wednesday with showers and thunderstorms possible each day. Flight restrictions are expected during showers and thunderstorms. Winds remain out of the south/southeast each day, becoming light and variable each night.

Most of any shower and thunderstorm activity may be held to MRB and CHO on Thursday. VFR conditions for the terminals, despite a brief MVFR development with convection. Winds southwest 5 to 10 knots. VFR conditions should start the day Friday, but MVFR to IFR conditions may develop Friday midday through Friday evening at any of the terminals. Once convection clears, VFR conditions should redevelop.
Winds southwest to west 5 to 10 knots.

MARINE
Light winds are expected over the waters through Tuesday. Winds remain below SCA criteria each day, blowing 5 to 10 knots Monday and Tuesday afternoon. Daily shower and thunderstorm activity may lead to SMWs being needed. Winds increase to near SCA criteria Wednesday evening due to southerly channeling. A Small Craft Advisory may be needed.

The only marine hazards that could occur Thursday through Friday night would be Special Marine Warnings for thunderstorms that could develop and move out over the Potomac River and Chesapeake Bay waters Friday midday through Friday evening. Winds generally southwest to west 10 knots with exception to higher gusts in thunderstorms.

TIDES/COASTAL FLOODING
A prolonged period of southeasterly winds will lead to elevated tidal anomalies through midweek. This carries most of the tidal locations into Action stage, particularly during the higher of the two astronomical high tide cycles. Sensitive locations, such as Annapolis, are forecast to stay just below Minor stage during the high tide cycles this morning.

LWX WATCHES/WARNINGS/ADVISORIES
DC...Flood Watch from 2 PM EDT this afternoon through this evening for DCZ001.
MD...Flood Watch from 2 PM EDT this afternoon through this evening for MDZ003>006-008-011-013-014-016>018-503>508.
VA...Flood Watch from 2 PM EDT this afternoon through this evening for VAZ025>031-036>040-050-051-053>057-501-502-505>508- 526-527.
WV...Flood Watch from 2 PM EDT this afternoon through this evening for WVZ051>053.
MARINE...Flood Watch from 2 PM EDT this afternoon through this evening for ANZ530.