Chester River to Queenstown MD Marine Forecast
|Rest Of Tonight...S Winds 10 Kt...Becoming W Late. Waves 1 Ft.|
|Wed...N Winds 5 To 10 Kt. Waves 1 Ft. A Chance Of Showers And Tstms.|
|Wed Night...E Winds 5 Kt. Waves Less Than 1 Ft. A Chance Of Showers And Tstms.|
|Thu...S Winds 5 To 10 Kt. Waves 1 Ft. A Chance Of Showers And Tstms.|
|Thu Night...Sw Winds 5 To 10 Kt. Waves 1 Ft. A Chance Of Showers And Tstms.|
|Fri...Nw Winds 10 Kt. Waves 1 Ft.|
|Fri Night...N Winds 10 Kt. Waves 1 Ft.|
|Sat...Nw Winds 5 To 10 Kt...Becoming S. Waves 1 Ft.|
|Sun...W Winds 5 To 10 Kt. Waves 1 Ft. A Chance Of Showers. Winds And Waves Higher And Visibilities Lower In And Near Tstms.|
| Area Forecast Discussion|
...UPDATED National Weather Service Baltimore MD/Washington DC
926pm EDT Tuesday July 27 2021
A weak frontal zone will remain draped near or over the Middle Atlantic through Wednesday, reinforced by disturbances aloft. A stronger cold front will cross the region Thursday into Friday. High pressure will follow for the first half of the weekend before another frontal boundary approaches by early next week.
Near Term - Through Wednesday
An isolated shower has developed over Augusta County this evening. Hoping that this is short-lived as there is an abundance of dry air per 00Z IAD RAOB. A thicker layer of smoke was also seen right around sunset over southern PA and western MD progressing southeast. Mainly clear, but hazy skies are expected overnight with lows ranging from the mid 60s in the mtns to the mid 70s along the bay.
Short Term - Wednesday Night Through Thursday Night
A shortwave trough currently over Saskatchewan in Canada is expected to cross the region Wednesday afternoon. This should enhance the pre-existing frontal zone/lee trough (possibly merging with another weak front/surface reflection). Lift from these features will act on the instability present to result in scattered afternoon and evening showers and thunderstorms. Modest flow aloft may lead to some loose organization, perhaps resulting in a focused cluster/corridor or two of gusty to damaging winds, but certainty in specifics is low a day in advance given the overall marginal environment for organization. Notably, the 12z HRRR (High-Resolution Rapid Refresh) mixes dew points to around 50 during the afternoon, whereas as the NAMNest holds dew points in the mid 60s (as does most other guidance). This plays a big role in available CAPE and subsequent depth of convection. Regardless, very steep lapse rates in the lower levels and ample DCAPE should result in an environment favorable for strong downdrafts/bursts in the stronger cells.
A much more potent (convectively augmented) shortwave trough and accompanying mid-level speed max are expected to pivot across the area Thursday afternoon. There are uncertainties in the extent of upstream convection and clouds which may temper instability, though the 12z guidance overall has trended higher with projected instability/CAPE. The seasonably strong trough and wind field with moderate to strong CAPE may result in one or more clusters of organized thunderstorms (perhaps initiating as more discrete cells for a time) capable of damaging wind and hail, heavy rain/flooding given high humidity, and even a tornado threat. The extent of severe weather will be highly dependent on the evolution of upstream convection over the next 48 hours as well as the magnitude of instability locally. Overall, the threat is marginal at this time due to low confidence, but with a high ceiling; a worst case scenario would be one where widespread gusty to damaging winds are observed due to the favorable background environment.
Temperatures should run a little above normal Wednesday through Thursday before heat and humidity take a tumble behind the front by the end of the week.
Long Term - Friday Through Tuesday
A few isolated showers are possible across our southern zones and bay waters both Friday afternoon and again Saturday evening with a weak boundary nearby. Otherwise, the weekend looks slightly cooler by a couple of degrees compared to previous days with highs in the middle to upper 80s. The warmer day appears to be Friday.
Later Sunday into Monday would be the next better chance of showers and thunderstorms as a cold front pushes in from the northwest and nearly stalls to the south by later in the day Monday. High temperatures will approach 90 ahead of the front but could be held in the middle to upper 80s in any cloud cover and convection.
Through early Thursday, wind outside of convection should stay under SCA (Small Craft Advisory) levels. There is some increase in southwesterly winds expected on Thursday which may require a SCA (Small Craft Advisory) for portions of the waters. A better chance for thunderstorms exists on Wednesday and Thursday, with Special Marine Warnings possible.
A Small Craft Advisory is possible Friday. Winds northwest 10 to 20 knots w/ higher gusts Friday. Winds diminishing northwest 5 to 10 knots Friday night and Saturday, becoming south 5 to 10 knots Saturday night.
NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...None. MD...None. VA...None. WV...None. MARINE...None.