Penobscot Bay Marine Forecast
|Today...N Winds 5 To 10 Kt With Gusts Up To 20 Kt. Seas 1 Foot Or Less, Then 1 To 2 Ft This Afternoon. Scattered Snow Showers Early This Morning, Then Isolated Snow Showers Late This Morning. Isolated Snow Showers Late. Vsby 1 To 3 Nm This Morning, Then 1 To 3 Nm Late.|
|Tonight...N Winds 10 To 15 Kt, Becoming Nw 5 To 15 Kt After Midnight. Seas 1 To 2 Ft In The Evening, Then 1 Foot Or Less.|
|Thu...W Winds Around 5 Kt, Becoming S In The Afternoon. Seas 1 Foot Or Less. Scattered Snow Showers In The Afternoon.|
|Thu Night...Nw Winds 5 To 10 Kt, Becoming N After Midnight. Seas 1 Foot Or Less. A Chance Of Snow Showers. Vsby 1 To 3 Nm In The Evening.|
|Fri...N Winds 5 To 10 Kt. Seas 1 Foot Or Less. A Chance Of Snow Showers. A Chance Of Showers In The Afternoon.|
|Fri Night...N Winds 5 To 10 Kt, Increasing To 10 To 15 Kt With Gusts Up To 20 Kt After Midnight. Seas 1 Foot Or Less. A Chance Of Snow Showers.|
|Sat...Nw Winds 10 To 20 Kt. Seas 1 Foot Or Less, Then Around 2 Ft In The Afternoon. A Chance Of Snow Showers In The Morning.|
|Sat Night...Nw Winds 15 To 20 Kt. Seas Around 2 Ft.|
|Sun...Nw Winds 15 To 20 Kt. Seas Around 2 Ft.|
|Sun Night...Nw Winds 15 To 20 Kt, Diminishing To 10 To 15 Kt After Midnight. Seas Around 2 Ft.|
| Area Forecast Discussion|
...UPDATED National Weather Service Gray ME
549am EST Wednesday Jan 20 2021
A clipper system crossing the area this morning will bring pockets of snow showers today. High pressure crosses the area tonight followed by another weak system late Thursday into Friday. High pressure builds in for the weekend and into early next week.
Near Term - Until 6pm This Evening
Update...Still snowing across the North Country webcams...so I have extended the duration of likely and higher Probability of Precipitation thru the mid morning hours. Otherwise no significant changes to the forecast.
Previous discussion...Well defined S/WV trough set to swing across the region this afternoon. Its approach has established a weak surface trough across the forecast area. It is within this zone aided by orographic ascent that I have the highest Probability of Precipitation early in the day for light snow. Opted for stratiform wording as it will be rather tough to distinguish individual snow showers. Generally looking at light precipitation and Quantitative Precipitation Forecast...but persistent nature may allow an inch or two of accumulation thru the day in the Northern zones.
As the trough axis swings thru this afternoon I have made sure at least slight chance Probability of Precipitation is in place for all zones...with slightly higher 25 to 40 percent chance in Srn half of NH. High-res guidance is more bullish on scattered snow showers in those zones closer to the upper forcing than farther N. Things should be rather progressive though...and very light accumulations expected.
Overall blended model guidance produced very little PoP today...so I had to manually increase forecast for zones I expect will be most likely to see flakes flying today.
Short Term - 6pm This Evening Through 6pm Thursday
Cold Air Advection expected in the wake of the upper trough tonight. Opted for more raw 2 m temp guidance in the blend vs MOS as the latter has a tendency to favor radiational cooling too much in these situations. May see some lingering upslope snow showers but flow aloft looks unlikely to maintain a persistent direction to establish an organized event.
The warm air advection wing of the next S/WV trough moves into the area late Thu. It will bring another threat of snow showers...most likely in the higher terrain where upslope flow helps to enhance the lift. Overall a similar look to today.
Long Term - Thursday Night Through Tuesday
A broad are of low pressure associated with a series of disturbances embedded within cyclonic flow aloft will cross the area Thursday night into Saturday morning. These disturbances will bring pockets of snow showers during this time with a drying trend the latter half of the weekend. Early next week a piece of southern stream energy will eject out of the Southwest with low pressure tracking east through the Mid-Atlantic. Current guidance tracks this system too far to our south to bring any precipitation with dry weather expected for this first half of next week.
A clipper-like area of low pressure will be dropping southeastward out Canada Thursday night into Friday. This will bring an extended period of chances for snow showers into Saturday morning although little accumulation is expected with the mountains fairing the best with a few inches. Main impacts from this system will be intermittent periods of snow covered roads and reduced visibility. High temperatures Friday will range from the 20s north to near 40 south.
The clipper system exits Saturday with only some upslope snow showers expected in the mountains. Colder air will be working into the region on brisk NW winds with winds gusting 20 to 30 mph Saturday afternoon. Highs will be below freezing for all for a change with teens north and upper 20s south. With the brisk NW winds windchills will be below zero in the mountains and the teens across the south.
High pressure will build in from the west Sunday while an area of low pressure strengthens in the Canadian Maritimes. There will be a decent PGF between these system over our are leading to another brisk day with winds gusting 20 to 30 mph and windchills staying below zero in the mountains and near 10 degrees south.
Early next week attention turns to a southern stream piece of energy ejecting out of the Southwest Monday. This piece of energy will lead to low pressure developing over the southern Plains and tracks eastward towards the Mid-Atlantic Monday night into Tuesday. Deterministic and the majority of ensemble members track this system east out into the Atlantic too far to our south to bring precipitation to our area. However, there are a couple ensemble member that do track the system far enough to bring accumulation snow to at least southern areas. This system will be one to watch over the next several days because it will likely have more Quantitative Precipitation Forecast to work with than the clipper systems we have been dealing with this week.
Winds and seas will increase in the wake of a passing trough today. Marginal SCA (Small Craft Advisory) conditions remain likely and SCA (Small Craft Advisory) remains in place for this afternoon and evening. Winds and seas diminish thru Thu.
Long Term...Conditions will be below SCA (Small Craft Advisory) thresholds Thursday and Friday. SCA (Small Craft Advisory) conditions expected over the weekend, at least over the outer waters, as pressure gradient between low pressure to our east and approaching high pressure drives gusty winds over the waters. Outside chance for gales Saturday night over the eastern outer waters.
NOAA Gray/Portland ME Office - Watches - Warnings - Advisories
Small Craft Advisory from noon today to 7pm EST this evening for ANZ150-152-154.