Marine Weather and Tide Forecast for Highland Beach, MD

NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
Mid to high level clouds approaching from the west will continue spreading eastward tonight ahead of an upper level cutoff low.
It will remain dry, though the southerly flow will continue overnight increasing Tds by daybreak. This will in part result in temps several degrees warmer than the past several nights. Lows will drop into the mid/upper 60s to mid 70s (upper 50s to lower 60s in the high elevation valleys).

SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/
The subtropical ridge will continue to build over Florida into the Atlantic and surface high pressure will strengthen over the Atlantic as a result. At the same time, the area of upper-level low pressure across the central/southern Plains today will shift east from the Plains into the Midwest/Tennessee Valley for Friday. Additionally, an area of low pressure well of to the north in Canada will continue to drag a slow-moving backdoor cold front towards the region from the north on Friday as high pressure builds north of the Great Lakes. The greatest bit of uncertainty lies with exactly how far south that boundary is going to drop into our region. This will likely be a focal point for convection during the afternoon/evening hours on Friday.

Given that the shortwave is still off to the west, and there isn't a lot of shear to work with, storms that fire early tomorrow afternoon are going to be slow-moving with little forcing/steering. They will also be developing in an air mass with temperatures in the mid to upper 80s and dew points approaching the low 70s, yielding CAPE values in the neighborhood of 1250 to 1500 J/kg. Pair that with a somewhat skinny CAPE profile and PWATs in the 2" range, and you start to worry about a decent flooding setup across the region. One thing that is even a bit more concerning is that once the backdoor front starts dropping southward, the southerly flow south of the front starts to help to squeeze some even higher PWATS out in some of the guidance (around 2.2" or so). Consideration for a flood watch was given, but opted to hold off for now to try to better pinpoint where the highest QPF totals will occur, which will largely vary depending on the frontal placement.
Additionally, the lapse rates in the low-levels are decent, and there is a bit of dry mid-level air in model soundings. This could help to accelerate some downdrafts and bring some gusty winds along with some of the stronger storms. This could cause storms to be a bit more cold pool dominant, thus maybe not resulting in as much training. This is one level of uncertainty as well, which was another reason to hold off for now. At any rate, tomorrow's thunderstorms are likely to bring some very heavy rainfall rates, so any given location picking up a quick inch or two in a short time span is not out of the question.
Picking where that will occur exactly is just something that is going to occur a little closer in time as we see all of the pieces coming together later this evening into the overnight hours.

Convection should wane overnight Friday/early Saturday morning, but plenty of moisture will remain in place and this may result in low clouds/areas of fog.

The upper-level low will continue to approach Saturday through Saturday night while a backdoor boundary approaches from the northeast. Plenty of moisture will remain in place for more showers and thunderstorms to develop (mainly during the afternoon and evening). PWATs look to remain high on Saturday, which when combined with an unstable atmosphere suggests that storms may contain heavy rainfall that leads to flooding once again. There is still some uncertainty as to exactly where the backdoor boundary sets up on Saturday as well, and consequently where the best lift and instability will be for the stronger storms to develop. Additionally, convection on Friday could even help to drive headline decisions on Saturday, if necessary, depending on which places get the most rain Friday. The CAMs are just coming into range with this, and are all depicting a somewhat similar scenario, being a strong MCS rolling through during the afternoon/evening. This could come with an isolated damaging wind threat, but especially heavy rain and lightning.
The main puzzle piece left is figuring out where the worst of that occurs, and that is still a bit uncertain, as mentioned previously. Recent guidance does still show that the best low- level convergence may set up near and to the south and west of the Potomac River. So perhaps this area could be the focal point, though I wouldn't count on that still a couple of days out. The position of that backdoor front is going to be the driving factor. The strongest storms will be most likely near/south of the front of course.

Convection should wane in coverage overnight Saturday, but a few showers along with low clouds and areas of fog will likely persist.

LONG TERM /SUNDAY THROUGH THURSDAY/
The backdoor boundary will likely stall out near the area Sunday through Monday while the upper-level passes through the area.
This will likely cause more showers and thunderstorms, and there is a threat for heavy during this time. Exact details remain uncertain, but the heaviest rain will most likely set up near and to the south/west of the backdoor boundary.

The upper-level low will move off to the east for Tuesday and Wednesday, but a nearly zonal flow aloft will persist along with additional weak disturbances passing through the area. This means more unsettled conditions will persist with chances for showers and thunderstorms (especially during the afternoon and evening hours each day).

AVIATION /01Z FRIDAY THROUGH TUESDAY/
VFR conditions are expected through tonight along with light winds. Showers and thunderstorms becoming increasingly likely Friday afternoon and evening. Have introduced TSRA into the 18z TAF updates towards the end of the period, along with PROB30 groups for a couple hours prior. This is due to potential storms firing earlier than anticipated.

Low clouds and fog are likely overnight Friday, especially in areas that receive rainfall, with IFR conditions possible.

An unsettled pattern with the likelihood for showers and scattered thunderstorms will persist for Saturday through Monday. Low clouds and areas of fog are possible during this time, especially during the nighttime and morning hours each day, resulting in subVFR and possible IFR conditions.

MARINE
Weak high pressure will move offshore tonight. Winds will remain light, but turning southerly this afternoon into tonight.
Southerly channeling will cause wind gusts to approach SCA criteria over the open waters, but confidence is too low for a headline at this time.

A southerly flow will usher in plenty of moisture Friday, and this will increase the chances for thunderstorms. Some stronger storms with gusty winds are possible during the afternoon and evening hours. A backdoor boundary will approach the waters Saturday and stall out nearby for early next week. More showers are likely with possible thunderstorms during this time.

TIDES/COASTAL FLOODING
The more sensitive tidal sites could continue to hit action stage during the higher of the 2 high tide cycles the next couple of days. But overall, anomalies will slowly drop.

LWX WATCHES/WARNINGS/ADVISORIES
DC...Air Quality Alert until midnight EDT tonight for DCZ001.
MD...Air Quality Alert until midnight EDT tonight for MDZ008-011- 013-014-504-506-508.
VA...Air Quality Alert until midnight EDT tonight for VAZ053-054- 505-506-526-527.
WV...None.
MARINE...Air Quality Alert until midnight EDT tonight for ANZ530.