Marine Weather and Tide Forecast for Washington, DC

KEY MESSAGES
- (1) Colder early this week with a fire weather threat Monday.

- (2) Widespread frost/freeze Monday night into Tuesday morning.

- (3) Warmer temperatures mid to late week.

DISCUSSION
KEY MESSAGE 1...Colder early this week with a fire weather threat Monday.

A strong cold front will continue to push offshore tonight while a secondary cold front approaches from the west. This second front will cross early Monday with high pressure building in its wake. Initial breezy conditions will abate this evening before picking up again Monday morning.

Very dry air will move overhead through Monday. However, there is a layer between roughly 6,000 and 12,000 feet where notable moisture is present. The thought is scattered to broken stratocu and wave clouds will develop out of this, especially as the secondary front pushes through early Monday, then the trailing shortwave/upper-level trough pivot overhead Monday afternoon. A few sprinkles or a pop up shower can't be ruled out (with a little snow likely above 2500 feet over the mountains). The nose of the shortwave aloft crosses roughly between I-70 and I-64 on Monday, and even if precipitation evaporates before hitting the ground (virga), very steep low-level lapse rates could result in some enhanced gustiness. Frequent gusts of 20 to 30 mph are expected through early this evening and again Monday, with peak gusts of 35 to 40 mph possible especially at higher elevations.

Dry and breezy conditions are expected through early this week.
Please refer to the Fire Weather section below for more details on the fire weather threat Monday.

KEY MESSAGE 2...Widespread frost/freeze Monday night into Tuesday morning.

High pressure builds overhead Monday night into Tuesday leading to lighter winds. The cold, dry airmass, clear skies and light to calm winds Monday night into Tuesday morning are likely to bring widespread frost/freeze conditions. Expanded the Freeze Watch across the remainder of the area, thinking that the very dry airmass and light winds will be favorable for strong radiational cooling outside the major urban centers and away from larger bodies of water.

This is ~10 days past the median date of the last spring freeze based on 1991-2020 climatology for areas along/east of I-81.
Given the warmth early this spring, many areas are ahead of schedule from a growth stand point so this freeze could be rather impactful.

There are no frost/freeze headlines for the Alleghenies as the growing season has not started there yet.

KEY MESSAGE 3...Warmer temperatures mid to late week.

Warmer air will work into the region for Wednesday through Saturday as upper-level ridging gradually builds in aloft. High temperatures are forecast to reach into the 70s to lower 80s each day, with overnight lows generally in the 50s. Much of the time period should remain dry, but a shower or thunderstorm can't be ruled out on Wednesday or Saturday as weakening cold fronts approach from the northwest.

AVIATION /18Z SUNDAY THROUGH FRIDAY/
Gusts of 20 to 30 kts will linger through this evening with lighter winds tonight. A secondary cold front likely results in 20- to 30-knot gusts again heading into Monday with a spotty shower possible. Otherwise, VFR through Tue. Winds shift to S by Tuesday, then SW Wednesday.

Prevailing VFR conditions are expected on both Wednesday and Thursday, although a brief reduction to sub-VFR can't be ruled out in any showers (or t-storms) on Wednesday. Winds are expected to be out of the southwest/west on Wednesday, before becoming light out of the northwest on Thursday.

MARINE
Winds become lighter tonight then increase again Monday with a secondary front. Light winds Monday night turn southerly Tuesday with additional SCAs possible late Tuesday into Wednesday.

Sub-SCA level winds are expected late Wednesday into Thursday.
Winds will generally be out of the southwest/west on Wednesday, before becoming light and variable on Thursday.

FIRE WEATHER
Some areas of the Shenandoah Valley and central Virginia piedmont received less than a quarter inch of rain this weekend.
These same areas have been the driest recently, and may also end up with the lowest humidity through Monday. That, coupled with the breezy conditions, results in an elevated threat for the rapid spread of fires. The potential of a more substantial cumulus field, recent greenup, and at least some rain across the area may keep a more significant threat at bay, hence no Fire Weather Watches have been issued.

LWX WATCHES/WARNINGS/ADVISORIES
DC...Freeze Watch from late Monday night through Tuesday morning for DCZ001.
MD...Freeze Watch from late Monday night through Tuesday morning for MDZ003>006-008-011-013-014-016>018-503>508.
VA...Freeze Watch from late Monday night through Tuesday morning for VAZ025>031-036>040-050-051-053>057-501-502-505>508- 526-527.
WV...Freeze Watch from late Monday night through Tuesday morning for WVZ051>053.
MARINE...Small Craft Advisory until 9 PM EDT this evening for ANZ530- 531-535-536-538>540-542.
Small Craft Advisory from 6 AM to 9 PM EDT Monday for ANZ530- 531-535-536-538>540-542.
Small Craft Advisory until midnight EDT tonight for ANZ532>534- 537-541-543.
Small Craft Advisory from 6 AM Monday to 4 AM EDT Tuesday for ANZ532>534-537-541-543.