Marine Weather and Tide Forecast for Indian Head, MD

KEY MESSAGES
-1) Cold front could bring severe thunderstorms this evening/tonight.

-2) Quiet weather expected through Wednesday with moderating temperatures late week. Shower chances return Thursday and Friday as a cold front approaches the region.

DISCUSSION
KEY MESSAGE 1...Cold front could bring severe thunderstorms this evening/tonight.

S'ly winds will persist through the day. This will result in low-level moisture increasing, with some potential for fog/low clouds by daybreak especially east of the Blue Ridge. Any low clouds or fog should burn off quickly this morning.

Notably warmer today with SW'ly flow advecting well above average temps into the region (H85 temps of 15-17C). Have added a climate section (below) to account for near record heat today. Most of the forecast area should climb into the 80s, with some locations potentially even making it into the mid- upper 80s.

Guidance has trended slightly slower with cold frontal passage across local area, potentially delaying storms until after sunset. The front itself is rather strong and will be over PA during peak heating. This will result in showers and thunderstorms developing north of us during the afternoon hours.
Across the local area, almost every sounding/model analyzed has capping through the day with a lingering EML. At this point, very low chance of storms developing ahead of the front. The aforementioned storms over PA will likely drift SE toward northern Maryland shortly after dark. As low-levels stabilize with loss of daytime heating, the trend should be for these storms to gradually weaken as they move into our FA.

The environment to our north across PA looks very favorable for the development of severe thunderstorms, with a CAPE/shear parameter space capable of producing both supercells and bowing segments. As storms do move in after dark, they could still potentially produce severe hail, even if they're elevated.
Today is a day to watch for severe thunderstorms, but as it stands now, it may be a near miss for most of the area, with the capping serving as a potential saving grace.

The day 1 SPC update has little change across the FA with a Slight Risk (Level 2 out of 5) in the northern third of the area and Marginal Risk (Level 1 out of 5) elsewhere. SPC also has far northwestern portions of the FA in a sig hail outlook (indicating the potential for 2+" hailstones). That hints at the potential high ceiling for the severity of storms tomorrow, if they maintain their strength southward into our forecast area.
As of now, the most likely timing for storms looks to be between 8 PM and Midnight, with remnant showers moving southward along with the cold front through the entire FA later during the overnight hours.

KEY MESSAGE 2...Benign weather is likely during mid week before a cold front brings higher rain chances Thursday night into Friday.

Winds will shift to out of the NW behind the cold front on Mon. Conditions will dry out and temps will be much cooler (but near normal), with highs for most in the 50s and lower 60s (40s mtns). Winds will gust to around 25-35 mph out of the NW.

High pressure will build overhead Tue with dry conditions and below avg temps.

Surface high pressure will continue to drift offshore Wed into Wed night with a subtle shortwave trof/weak backdoor front passing across the area Thu. This will touch off a few light showers across the mtns and northern portions of the FA.
Confidence in this occurring is low given ample dry air leftover in the low levels with high pressure close enough offshore to provide some lingering influence across the area.

Meanwhile, surface low pressure will work across the St. Lawrence Valley of Canada. This low will eventually shove a frontal zone southward into the area late Thu night into Fri. The front will be slow to cross Fri with due to the placement of the low up over Canada/northern Great Lakes and an incumbent deepening trough ejecting east from the southern Plain/Mid-South region.
The front will sag southward as a cold front Fri evening into Fri night while becoming parallel to the upper level flow.

With that said, plenty of model spread remains per the latest 00z guidance in regards to timing, placement of surface features, temperatures, and rain amounts late week. Thus the position of this potentially wavering frontal zone may have some impacts on temps Thu and Fri, though they should be near or above normal.

Most of the guidance has the front south of the area Sat with Canadian high pressure building back over the region. This will a bring a return to near or slightly below normal temps for the weekend.

AVIATION /06Z SUNDAY THROUGH THURSDAY/
S'ly winds expected to continue through the day ahead of cold frontal passage. There remains a signal that low clouds and/or fog may try to form by daybreak. For now, TAFs have been kept MVFR, but IFR CIGs are hinted at with a scattered group. Any low clouds or fog should quickly burn off this morning, leading to VFR conditions once again through much of the day. Winds will gradually pick up out of the SW, and could gust around 20 to perhaps 30 kts during the late afternoon/evening hours.

Aforementioned cold front will bring shower and t-storm chances this evening/tonight. Sub-VFR CIGs and VSBYs may both be possible at times. Any precip should come to an end by daybreak Mon, but winds will remain gusty (25-35 knots) out of the NW during the day Mon.

VFR conditions are expected with Canadian high pressure Tue and Wed. Sub-VFR conditions return for some terminals Thu as a backdoor front drops into the region. S'ly winds may gust to around 25 kts on Thu as a low pressure system passes well to the north. More widespread sub-VFR conditions are expected with a strong cold front Fri.

MARINE
Sub-SCA s'ly winds continue through daybreak. Winds gradually pick up out of the S to SW through the day, and could reach low-end SCA levels by the late afternoon/evening hours. However, warm air moving over much cooler waters could limit mixing and resultant wind speeds, especially over the wider waters. One place mixing should be efficient is over the middle and upper tidal Potomac River (narrower waterways) so have an SCA to account for this.

A strong cold front will move over the waters tonight, causing winds to shift to out of the N. Showers and a few thunderstorms may accompany the frontal passage, with the best chance for storms across northern portions of the Bay (SMWs may be needed).
Chances for precip will come to an end by daybreak Mon, but winds will remain gusty out of the NW through the day. SCAs will likely be needed Mon into Mon night.

High pressure will provide light winds Tue. SW winds may begin to increase Tue night into Wed and may approach SCA levels. SCAs possible Thu and again Fri as the next front pushes in.

CLIMATE
Record daily high temperatures are possible on Sunday (March 22).
Below is a list of records for the date.

Site Record/Year Set DCA 90/1907 BWI 86/1907 IAD 83/1968 DMH 79/1955 NAK 82/1948 HGR 88/1907 MRB 84/1966 CHO 92/1907

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 2 PM this afternoon to 6 PM EDT this evening for ANZ535-536.