Marine Weather and Tide Forecast for Riva, MD

KEY MESSAGES
- (1) First widespread (albeit light) rain this morning in over a week.

- (2) Fire weather possible this afternoon and Monday.

- (3) Widespread freeze expected Monday night.

DISCUSSION
KEY MESSAGE 1...First widespread (albeit light) rain this morning in over a week.

Intermittent SHRA will be the story through this morn and into the aft east of I-95 as a cold front progresses eastward.
Rainfall amounts as of 2AM are on the higher side of previous guidance (generally two tenths to a half inch across the NW FA).
Perhaps this is a telling sign as we move through the morning, as any additional few hundredths or tenths will be beneficial given ongoing drought. Overall, still expecting a general one to three tenths with localized spots near a half an inch. As the cldfrnt moves E, S/SE winds will quickly shift to W/NW today.
Winds could gust 40-45 mph immediately behind the front. High temps today will be reached early in the day.

KEY MESSAGE 2...Fire weather possible this afternoon and Monday.

Depending on how much rain falls this morning and how quickly things dry out with blustery W/NW wind at ~25 mph or so, there could be a fire weather threat mainly west of the Blue Ridge.
Areas further east have less time drying out and generally weaker winds.

Following a secondary cold front Mon, a strong upper-level trof and sw will pivot overhead. Very cold air at 850-500 hPa will result in very steep lapse rates, with deep inverted-V profiles noted in forecast soundings up to 8-12 kft. This will result in wind gusts of 20 to 30 mph as dry low-level air moves in. Given mid-level moisture and the sw, some cloud cover and a few sprinkles or even a light/brief graupel shower can't be ruled out. Did undercut NBM temps by a degree or two in most areas given the cold airmass.

With the overlap in very dry air and strong winds, the fire wx threat Mon needs to be monitored. It is conditional and based on how much rain falls. More detail in fire wx section below.

KEY MESSAGE 3...Widespread freeze expected Monday night.

High pressure builds overhead Mon night into Tue leading to lighter winds. The cold, dry airmass, clear skies and light to calm winds Mon night into Tue morning are likely to bring widespread frost/freeze conditions. Issued a Freeze Watch where confidence is >50% for low temps less than 32F Mon night. 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. Should be noted areas in srn MD and east of I-95 still have a frost threat as temps generally hover 33-35F.

No frost/freeze headlines for the Alleghenies as the growing season has not started yet.

AVIATION /06Z SUNDAY THROUGH THURSDAY/
An abrupt wind shift to the NW is expected 06Z-12Z Sun with FROPA. Some MVFR is possible Sun AM. Gusty winds of 30 to perhaps 40 kts are possible for a brief time right after FROPA.
Gusts of 20 to 30 kts then linger through this eve with lighter winds tonight. A secondary cold front likely results in 20 to 30 kt gusts again heading into Mon with a spotty shower.
Otherwise, VFR Sun night through Tue. Winds shift to S by Tue.

Although a few showers are possible on Wed, expect mainly VFR conditions. This theme continues into Thu as drier air moves in behind the cold front. In response to this cold front, W to SW'ly winds may gust to around 15 to 20 knots. Winds on Wed night into Thu become lighter and out of the N.

MARINE
Winds have subsided aside from wider waters off southern MD as of 2 AM. An abrupt wind shift to the NW is expected between 4 AM and 8 AM this morning from NW to SE, with gusts of 30-40 kts for a brief time likely necessitating SMWs even if there is little to no precip as a strong cold front crosses the waters.

Showers and gusty winds (SCAs) linger behind the front, with drying expected this aft. Winds become lighter tonight then increase again Mon with a secondary front. Light winds Mon night turn s'ly Tue with additional SCAs possible by Tue night.

An uptick in sw'ly winds is possible on Wed morning which may warrant SCAs over the srn waters. However, winds largely decrease to below SCA levels through the remainder of Wed into Thu as winds shift to N'ly behind the front.

FIRE WEATHER
Rain amounts may average a tenth to three tenths of an inch and may not be sufficient to wet fuels significantly. It should be noted some hi-res guidance does have localized amounts near a half an inch, but pinpointing the exact locations of these spotty amounts is very difficult. Strong gusty winds of 35 mph with potential for gusts as high as 45 mph will create renewed fire weather concerns despite marginal humidities and the overall light rainfall more so on Mon. Given the short duration of precip (6 hours or less for most), the 100-hour fuel moisture values aren't likely to rise much at all. The 10-hour fuel moisture likely rises considerably, but drops quickly through the day today due to the drying effects of strong winds and rapidly lowering humidity especially west of the Blue Ridge and Catoctin Mountains.

Much cooler temperatures are expected Mon and Tue with a moderating trend in temps expected during the middle and second half of the week. Strongest winds look to be on Mon out of the NW with gusts to 25 mph (30 mph over ridges). For the rest of the week, winds will be on light side thanks to high pressure overhead, but humidities will be marginally low to near critical levels. The next potential for rainfall is Wed into Thu, but amounts look light again.

TIDES/COASTAL FLOODING
SE flow will cause tides to rise to around or a little over one foot above normal through early this morning ahead of a strong cold front. Minor tidal flooding is possible at several sites especially for the waters around central to southern MD, with near moderate flooding possible in a high-end scenario at Annapolis (though a wind shift to the NW right around high tide should prevent that).

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Small Craft Advisory from 6 AM this morning to 6 PM EDT this evening for MDZ008.
Freeze Watch from late Monday night through Tuesday morning for MDZ003>006-008-011-503>508.
Coastal Flood Advisory until 10 AM EDT this morning for MDZ014.
VA...Freeze Watch from late Monday night through Tuesday morning for VAZ025>031-036>040-050-051-053-055-056-501-502- 505>508-526-527.
WV...Freeze Watch from late Monday night through Tuesday morning for WVZ051>053.
MARINE...Small Craft Advisory from 6 AM this morning to 6 PM EDT this evening for ANZ530>533-535-536-538>542.
Freeze Watch from late Monday night through Tuesday morning for ANZ530.
Small Craft Advisory until 6 PM EDT this evening for ANZ534- 537-543.