Marine Weather and Tide Forecast for North Chevy Chase, MD

KEY MESSAGES
- 1) Showers and a thunderstorm or two will develop along a surface front into early this evening near I-64. The front will push south of the region overnight.

- 2) Cooler conditions anticipated Monday into Tuesday.

- 3) Heat, humidity, and thunderstorm chances return mid to late week, with heat index values possibly approaching 100.

DISCUSSION
KEY MESSAGE 1...Showers and a thunderstorm or two will develop along a surface front into early this evening near I-64. The front will push south of the region overnight.

A couple of showers and a thunderstorm or two could develop in parts of the central Shenandoah Valley and Virginia Piedmont where the front is stretched across the regions. The I-64 corridor could be affect by this convection. The main threats will be 55-65 mph wind gusts and small hail in the strongest thunderstorms. The front is expected to continue to move southward overnight tonight and through the day Monday. Cooler temperatures will evolve overnight with high pressure moving in from the northwest.

KEY MESSAGE 2...Cooler conditions anticipated Monday into Tuesday.

High pressure is expected to build into the Mid- Atlantic early this week in the wake of the front. Cooler and drier air will work its way into the region. Sure our temperatures may still be a couple of degrees above average, but should be a couple of degrees cooler than the past 2 days and the humidity should be less too. High pressure moves to the east later Tuesday to allow for an isolated shower or two to possibly develop in the Alleghenies with the next disturbance.

KEY MESSAGE 3...Heat, humidity, and thunderstorm chances return mid to late week, with heat index values possibly approaching 100.

Heat will begin to build Wednesday as the surface high moves off the coast. Ensemble temperature plots suggest Thursday and Friday will be the hottest days with temperatures potentially well into the 90s. The heat index may rise above 100 degrees in some areas as dew points will be higher these days compared to some of our recent hot days.

The higher theta-e airmass will arrive on Wednesday as well, with several opportunities for showers and thunderstorms spreading across the area. Beyond that, there are uncertainties with how strong mid/upper level ridging will be, and when exactly shortwaves may approach from the northwest. In the end, there is some shower and thunderstorm potential (mainly diurnal) Thursday through Saturday, even if it is ultimately terrain-driven and limited in coverage. There may be some severe weather risk given the heat and humidity, although it may be isolated due to relatively weak shear (assuming a stronger trough does not unfold).

A cold front will approach from the north over the weekend, although it may not have much of a southward push. The upper level pattern will be flattening, however, so temperatures should trend down a little.

AVIATION /18Z SUNDAY THROUGH FRIDAY/
VFR conditions through Tuesday. A brief heavy shower or thunderstorm could develop or makes its way near CHO but there is low confidence of one impacting the terminal later this afternoon. Winds northwest becoming southeast around 10 knots through tomorrow at the terminals with high pressure building.
The winds should shift to the south once the high moves east on Tuesday.

Thunderstorms are possible during the afternoon and evenings of Wednesday through Friday. Winds likely remain 10 kt or less out of the south or west.

MARINE
SCAs remain in effect for the upper and middle Tidal Potomac, as well as for the northern and central Chesapeake Bay waters through early this evening. Winds northwest 10 to 15 knots gusts higher through this evening, becoming northeast overnight and Monday. Winds becoming southeast 10 to 15 knots late Monday through Tuesday.

Southerly flow may peak Wednesday into Wednesday night, so Small Craft Advisories may be needed. Overall winds may trend lighter Thursday and Friday out of the south or west.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Small Craft Advisory until 8 PM EDT this evening for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ530>533-535-536-538-542.