Casco Bay Marine Forecast
|Today...Sw Winds 10 To 15 Kt. Seas 2 To 4 Ft.|
|Tonight...Sw Winds 10 To 15 Kt, Becoming W 5 To 10 Kt After Midnight. Seas 2 To 4 Ft.|
|Tue...Nw Winds 5 To 10 Kt, Becoming N In The Afternoon. Seas Around 2 Ft.|
|Tue Night...N Winds 5 To 10 Kt. Seas Around 2 Ft.|
|Wed...N Winds 5 To 10 Kt. Seas 1 To 2 Ft.|
|Wed Night...N Winds 5 To 10 Kt. Seas 1 To 2 Ft.|
|Thu...N Winds Around 10 Kt. Seas 1 To 2 Ft. A Chance Of Showers.|
|Thu Night...Nw Winds 5 To 10 Kt. Seas 1 To 2 Ft. A Chance Of Showers In The Evening.|
|Fri...Nw Winds Around 10 Kt. Seas 1 To 2 Ft.|
|Fri Night...Nw Winds 5 To 10 Kt. Seas 1 To 2 Ft.|
| Area Forecast Discussion|
National Weather Service Gray ME
1057am EDT Monday September 27 2021
A cooler pattern develops this week as an upper level low settles in overhead. First, a low pressure system moves through with rain showers today into tomorrow as a cold front sags southward through New England. A mix of sun and clouds is expected through the duration of the week with the best chance for additional showers coming late Wednesday through Thursday. The pattern becomes less certain this weekend as upper level low pressure attempts to make an exit.
Near Term - Until 6pm This Evening
1045 AM...Timing of clouds/showers adjusted a little but no majorchanges for forecast today into tonight. Cold front and upper level support are currently vertically line up, but during this afternoon, will upper level wave shift NE will front moves SE. This means best chance of showers will be in the CT valley early this afternoon, and in the mtns this after into the evening. I have stuck closest to a blend of the meso models consensus. There is some suggestion that a few showers make it into the ME coastal plain later this afternoon, but very scattered, so I have added slt chance POPS to this region. Otherwise, forecast was unchanged.
650amUpdated some sky conditions this morning as a shelf of mid cloud has proceeded through New York quickly. Coverage will vary as it travels over the various mtn ridges and valleys. Generally expect greatest coverage west of the NH/ME mtns, with perhaps some cloud streets developing in the lee across the foothills and coastal plain this afternoon. Low temp of the night goes to Mount Washington, dipping to freezing and experiencing their first glaze ice event since June 23. While temps will rise into the low 40s there today, winds will keep wind chills in the teens to lower 20s.
Previous Discussion... Partly to mostly sunny skies are expected early this morning as high pressure exits to the east. To the west, an approaching cold front will bring increasingly cloudy skies to NH and western Maine through the late morning to early afternoon.
Much of the cloud cover will reside atop and to the west of the higher terrain early, with downsloping delaying widespread coverage until more moisture arrives in proximity to the cold front.
Near the higher terrain is also where much of the rain shower activity is anticipated. Downsloping will cap much of the front's potency for the coastal plain, but cannot rule out an isolated showers as the afternoon wears on. Perhaps the more notable item here will be the breezy conditions as SW winds gust up to 25 mph amid good mixing under a strengthening LLJ off the S New England coast.
Despite the cold front's advancement, the generally warm mid to low levels limit much in the way of thunder potential. Trended high temperatures lower with cloud cover expected to limit the weakening sun's influence for the mtns and foothills.
Short Term - 6pm This Evening Through 6pm Tuesday
The cold front will continue to slide through the CWA through tonight, with showers expected to decrease in coverage through the ME coastal plain and southern NH.
Low pressure amid the front is forecast to strengthen across PA as it drifts east tonight. This should set up a fairly tight gradient of precipitation for S NH, with much of the associated rain falling across southern New England Tuesday. Looking at the suite of hires guidance, kept Probability of Precipitation low and left the mention of thunder out. Trends have been to reduce the amount of elevated instability with this system.
Long Term - Tuesday Night Through Sunday
The Autumn season is in full swing through the middle and end of this week as low pressure cuts off overhead, bringing in a cooler northwest wind and chances for rain showers. Looking to global ensembles through the period, there is strong agreement WRT cut off low pressure lingering over the region through at least the close of the work week, after which downstream blocking leads to a murkier wave progression. Nonetheless single-digit h850 temperatures limit high temperatures to the 50s and 60s with overnight lows in the 30s and 40s... flirting with the freezing mark at times in sheltered valleys especially across the north, depending on cloud cover.
Starting Tuesday night... low pressure and an attendant cold front will sag southeast offshore with showers ending and skies partially clearing. Northwest flow will persist behind this front through the end of the week with high pressure building to our west over the Great Lakes region. Looking aloft, a northern stream trough cuts off nearly overhead by Thursday... as this occurs, low pressure off the coast of the Canadian Maritimes retrogrades back west slightly. This combined with the descending cold pool(a region of relatively cold air) and broad vorticity maxima provide the best opportunity for cloudy skies and rain showers late Wednesday through Thursday... with flakes in the cards across the highest peaks of the Presidentials. Upsloping showers persist into Friday. After this point, the question turns to how the blocky northern hemispheric pattern evolves WRT the movement of the upper level low. Generally speaking flow should flatten aloft with low pressure shifting east at some point this weekend, with a modest warm trend expected.
Winds and wave heigheights will increase this afternoon, with SCA (Small Craft Advisory) conditions expected. Southerly winds will gust around 25 kts ahead of an approaching cold front, while wave heigheights respond 3 to 6 ft. Conditions improve around daybreak Tuesday.
Low pressure to the east and high pressure to the west will set up a general offshore flow regime through the end of the week with winds expected to remains at or below SCA (Small Craft Advisory) thresholds. For the seas however long period swells near 5 ft from distant tropical activity may develop late by the weekend.
NOAA Gray/Portland ME Office - Watches - Warnings - Advisories
Small Craft Advisory from 2pm this afternoon to 6am EDT Tuesday for ANZ150-152-154.