Marine Weather Net

Casco Bay Marine Forecast


TODAY

NW
WINDS
10 - 15
KNOTS

TONIGHT

W
WINDS
5 - 10
KNOTS

WED

S
WINDS
5 - 10
KNOTS

WED NIGHT

SW
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
ANZ153 Forecast Issued: 325 AM EDT Tue Mar 19 2024

Today...Nw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft.
Tonight...W Winds 5 To 10 Kt. Seas Around 2 Ft.
Wed...S Winds 5 To 10 Kt With Gusts Up To 20 Kt. Seas Around 2 Ft. Scattered Showers In The Afternoon.
Wed Night...Sw Winds 10 To 15 Kt With Gusts Up To 20 Kt, Becoming W 15 To 20 Kt With Gusts Up To 30 Kt After Midnight. Seas 2 To 3 Ft. A Chance Of Rain In The Evening.
Thu...W Winds 25 To 30 Kt With Gusts Up To 40 Kt. Seas 2 To 4 Ft.
Thu Night...Nw Winds 25 To 30 Kt With Gusts Up To 40 Kt. Seas 2 To 4 Ft.
Fri...Nw Winds 15 To 20 Kt With Gusts Up To 30 Kt, Becoming W 10 To 15 Kt With Gusts Up To 20 Kt In The Afternoon. Seas Around 2 Ft. Light Freezing Spray In The Morning.
Fri Night...W Winds 5 To 10 Kt, Becoming Se After Midnight. Seas 1 Foot Or Less. A Chance Of Snow After Midnight With Vsby 1 Nm Or Less.
Sat...Se Winds 10 To 15 Kt, Increasing To 15 To 20 Kt In The Afternoon. Seas 2 To 3 Ft. Snow Likely. Rain Likely In The Afternoon. Vsby 1 Nm Or Less.
Sat Night...S Winds 15 To 20 Kt, Becoming Nw After Midnight. Seas 2 To 3 Ft, Building To 3 To 5 Ft After Midnight. Rain Likely, Mainly In The Evening. Vsby 1 Nm Or Less.
SHARE THIS PAGE:           
Area Forecast Discussion
National Weather Service Gray ME
416am EDT Tuesday Mar 19 2024

Synopsis
Mountain snow showers gradually diminish today as cyclonic flow weakens ahead of an approaching clipper. The clipper brings more widespread snow showers Wednesday and Wednesday night, with a period of accumulating snow likely across northwestern areas Wednesday night into Thursday. Strong gusty winds follow the system on Thursday as cool high pressure builds into New England through Friday. Low pressure likely brings a more widespread round of accumulating snowfall on Saturday, with another storm possible late in the weekend. Unsettled conditions may linger into early next week as the pattern becomes much more uncertain.

.NEAR TERM /TODAY THROUGH TONIGHT/... A shortwave trough axis driving snow showers through the mountains this morning exits east today, leaving a cooler, more seasonable airmass in its wake along with a brief dry trend. Deep cold advection in cyclonic flow keeps lapse rates steep and mixing strong... allowing flow to become unblocked once again, which will have clouds track toward the coast. Precipitation diminishes by this afternoon as weakly diffluence flow and a shortwave ridge axis move in from the west. For sensible conditions, there is still a fair amount of mid-level moisture evident in modeled fields and satellite imagery this morning, so I think another day of stratocu is a fair forecast for the region, along with highs in the 30s and 40s. Well- mixed gradient flow ensures a steady WNW breeze gusting near 20 mph.

The shortwave ridge crossing this evening will allow winds quickly diminish, although hot on its heels will be falling heigheights associated with the next approaching system. Light snow showers are forecast to enter the Connecticut River Valley around or after sunset, and will continue to overspread the mountains overnight... perhaps spilling into the foothills and toward the coast toward dawn. Temperatures will be mostly in the 20s... except teens in the northern ME Lakes region, and 30s toward the Lower Merrimack.

Short Term - Wednesday Through Wednesday Night
A clipper tracking through a negatively tilted trough rolls through New England Wednesday into Thursday, bringing a bout of showers and accumulating snow. Snow shower activity mostly across the mountains through the morning will expand in coverage with the diurnal trend, and as a pre-frontal trough axis shifts SW to NE through New England... mixing with rain toward the coast, and becoming more rain than snow over the interior as temperatures warm. Temperatures are forecast to reach into the 40s for most places, as mixing and breaks in the clouds will allow sun to help in some places... although wet-bulbing and shower intensity ought to keep wet flakes around in the foothills.

One of the bigger questions with the system is the degree to which precipitation with this system will be stratiform vs showery. Broad warm frontal forcing may support more stratiform precipitation in the morning. During the daytime, CAMs entering the forecast range suggest steep lapse rates from deep Cold Air Advection combined with strong mixing aided by surface heating favors more showery precipitation and also contributes to elevated snow squall parameters during the day Wednesday across the mountains. While snow accumulation would be more hit or miss, showers could be briefly intense and lay down a quick dusting up to an inch or so.

Better stratiform potential exists during the evening and overnight, when a vorticity maximum barrels in from the west to quickly deepen the surface low as it reaches coastal Maine. The negatively tilted trough extending to the coastal low may place the Maine mountains in a favorable position for banded snowfall, with the added benefit of westerly to northwesterly upslope flow. Being the NW quadrant of the low... the conceptual model favors higher snow ratios too, with cold advection behind the low bringing thermal profiles into the snow growth zone, overlapping with mid-level ascent. Meanwhile further south and west, dry slotting would diminish precipitation potential, except in the upslopes... with a gusty west wind eventually mixing in as the low exits east. It is important to note that a shift northward of the upper level wave may dry slot up to the international border... leading to little additional accumulation other than from showers.

All in all snowfall totals may necessitate a winter weather advisory, especially when considering the spirit of it as a travel- oriented product. While showery activity during the day time would hardly amount to and inch or two across the mountains, there is certainly some good upward potential for heavier snowfall totals later in the evening and overnight toward the north if they get under a ban d. While ensemble means point to Quantitative Precipitation Forecast of around 0.3-0.5" between Bangor and the Maine mountains, medians are higher, suggesting a skew toward higher- end snowfall potential... especially across the peaks and ridges. Current forecast calls for accumulations up up to 7-10 inches near the international border, and across the summits elsewhere... with valley totals more in the 3-5 inch zone. But, this could be a feast or famine situation depending on mesoscale influence.

Long Term - Thursday Through Monday
Overview... Low pressure pulls away on Thursday, with windy conditions behind the system. High pressure crosses through on Friday, and then one or two systems likely affect New England from Saturday through early next week.

Details... The strengthening low pressure system moves through eastern Maine and into New Brunswick Thursday morning. Snow transitions to more snow showers across northern areas Thursday morning, while most other areas dry out by midday. Westerly winds quickly become gusty and strong, with gusts over 50 mph possible during the daytime on Thursday as the strong low pulls away, and high pressure builds in. Outside of the mountain peaks, winds look to be strongest across southern New Hampshire. Wind headlines may be needed for this set up.

Winds ease Thursday night, but breezy conditions likely continue into Friday morning. Temperatures will also be cooler than we've experienced most of this month, so it will feel cold overnight Thursday as lows dip into the teens, and wind chills dip into the low single digits to below zero. By late Friday, high pressure will have progressed far enough eastward to bring calmer conditions. The high will be progressive, with the ridge axis crossing through Friday night and moves toward Newfoundland through Saturday night. A stronger high builds to the north across Quebec and Labrador through weekend, reaching near 1050mb by early next week.

The forecast for the weekend has shifted significantly since 24 hours ago as the Euro and it's ensembles have tracked northwestward by several hundred miles with the weekend system, a solution the GFS (Global Forecast System) alone was showing yesterday. This appears to be in part from a shortwave in the northern branch being more amplified on Saturday, and the high being located further north, rather than across New England. Now, the northern system alone looks to have the potential to bring accumulating snow to much of the area on Saturday, while another stronger storm develops off the Carolina coast.

The break in the ridge provided by the northern branch shortwave allows the southern storm with its rich moisture to be drawn further north. The GFS is now showing a solution where the northern branch phases more with the southern system, and the Euro is very close to making this solution happen as well. Several Euro ensemble members are showing this now, and we will need to monitor if this trend continues over the next few runs. With such a large shift in the Euro from last night, it's not unreasonable to think it will shift further to more of the phasing solution, rather than the cut off low off the Carolina coast solution. If this happens, there is then much more moisture in play with the system for New England, and a rain/snow line this would be highly dependent on the track. With multiple shortwaves, a potential cut off low, and a strong high present, there are many moving parts that will need to be sorted out over the next day or two before a clearer picture arises.

Beyond this weekend the forecast for early next week becomes highly uncertain, with options ranging the chance for a cut off low meandering offshore bringing precipitation, to a cold dry airmass behind a departing low pressure system. These details will become more clear once the weekend system becomes better sorted.

Marine
Short Term
Breezy west flow at or below 25 kts today diminishes below 15 kts tonight, coinciding with 3-5 ft seas diminishing below 3 ft. Flow returns out of the SSW on Wednesday approaching SCA (Small Craft Advisory) thresholds, then turns W overnight with a crossing front. Wind gusts will increase from there, to around 30-35 kts by dawn Thursday.

Long Term
Westerly gales are possible Thursday and Thursday night as a strengthening low pressure center moves into New Brunswick Thursday morning. High pressure builds in behind the low and crosses the waters late Friday. Low pressure tracks eastward across the waters on Saturday. A stronger low develops off the Carolina coast this weekend, and may track northward into the Gulf of Maine by Sunday.

NOAA Gray/Portland ME Office - Watches - Warnings - Advisories
ME...None. NH...None.

Marine
None.