Marine Weather Net

Casco Bay Marine Forecast


TODAY

W
WINDS
5 KNOTS

TONIGHT

SW
WINDS
5 - 15
KNOTS

THU

W
WINDS
5 - 10
KNOTS

THU NIGHT

NW
WINDS
5 KNOTS

The Marine Weather Forecast In Detail:
ANZ153 Forecast Issued: 638 AM EST Wed Jan 22 2020

Today...W Winds Around 5 Kt, Becoming Sw This Afternoon. Seas 1 Foot Or Less.
Tonight...Sw Winds 5 To 15 Kt With Gusts Up To 20 Kt. Seas 1 Foot Or Less.
Thu...W Winds 5 To 10 Kt, Becoming Sw In The Afternoon. Seas 1 Foot Or Less.
Thu Night...Nw Winds Around 5 Kt, Becoming Ne After Midnight. Seas 1 Foot Or Less, Then 1 To 2 Ft After Midnight.
Fri...Ne Winds 5 To 10 Kt. Seas Around 2 Ft.
Fri Night...Ne Winds 5 To 10 Kt. Seas Around 2 Ft.
Sat...E Winds 5 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 4 Ft.
Sat Night...E Winds 15 To 25 Kt With Gusts Up To 30 Kt. Seas 4 To 7 Ft. Rain With Snow Likely. Vsby 1 To 3 Nm.
Sun...Ne Winds 15 To 25 Kt With Gusts Up To 35 Kt. Seas 5 To 8 Ft. Snow And Rain. Vsby 1 To 3 Nm.
Sun Night...N Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 3 To 5 Ft. Snow And Rain Likely. Vsby 1 To 3 Nm.
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Area Forecast Discussion
National Weather Service Gray ME
643am EST Wednesday Jan 22 2020

Synopsis
The region will continue to be dominated by high pressure through today providing for fair weather and a warming trend. A cold front will drop down from the north tonight with little in the way of adverse weather other than cooler temperatures. A coastal storm may bring accumulating snow to much of the region over the weekend into early next week, but rain and mixed precipitation are also possible depending on system track.

Near Term - Until 6pm This Evening
Update... Have updated the forecast based on current observations and latest set of mesoscale models. Clouds continue across the region with the exception of southern New Hampshire and extreme southwestern Maine. Clear skies in the south allowed for the coldest temperature readings this morning. Have adjusted temperatures and cloud forecast for the next few hours. Have also introduced the possibility of a brief snow shower or flurry over northern sections this morning.

Prev Disc... Warm air advection will continue today, bringing clouds to the region, especially during the morning hours.

H8 temperatures climb to about -1C over much of the region as heigheights rise along the East Coast. This will allow temperatures to climb into the 30s in most areas with perhaps a few upper 20s in the far north.

Short Term - 6pm This Evening Through 6pm Thursday
Mainly clear skies and light winds will allow for radiational cooling tonight. Despite a mild day, temperatures overnight will fall into the single numbers in the north to the teens in the south.

The ridge will allow for more sunshine on Thursday and mild temperatures as winds continue out of the southwest, both at the surface and aloft. With nearly full sunshine, temperatures will reach the lower 40s over southern areas.

Long Term - Thursday Night Through Tuesday
By the end of this work week, ridging over the Mid-Atlantic coast breaks down as Pacific energy amplifies over the Rockies and digs southeastward into the Plains and Mississippi River Valley. An 850 mb thermal ridge, a couple degrees either side of 0C, hangs around Thursday night into Friday, meanwhile surface high pressure strengthens out of the north which ought to lead to one more night in the teens under cool northerly flow, possibly the single digits in sheltered valleys of higher terrain. Increasing high level clouds, depending on what level they actually come in at, could encumber cooling so I haven't invested fully in MOS guidance in this case.

By Friday, high pressure shifts northeastward while heigheights aloft begin to fall in response to the developing trough and accompanying surface low pressure over the central CONUS. The digging trough links with southern stream energy and moisture as upper level flow becomes increasingly zonal over Canada. This leads to the low closing off to some degree over the southern Great Lakes, with a complex surface set-up featuring an occluding low over the upper Ohio Valley and a developing low over the Piedmont. As the Piedmont low moves northeastward into the Mid-Atlantic and eventually southern New England around the middle of the weekend, zonal flow over Canada leaves the eastern third of the CONUS into eastern Canada wide open to the development of a healthy warm sector aloft.

As prior discussions have noted, numerical models tend not to handle finer details of closed-low scenarios well. This is evident in ensemble model analysis; North American ensembles highlight sensitivity to north/south system track and strength of coastal development in the low/mid levels over southern New England. A tertiary source of uncertainty would be the strength of high pressure over the Canadian Maritimes and its bearing on system timing. Meanwhile the ECMWF (European Centre for Medium-Range Weather Forecasts) ensemble paints broad, 10-15 C spread in 850 mb temperatures across the forecast area in spite of fairly well- correlated 500 mb heigheights given the warm airmass advected into place.

Thus precipitation type over at least southern NH and coastal ME will be the primary challenge with the weekend system in spite of deterministic model (GFS, ECMWF, CMC) output showing decent agreement on system strength and track. With this in mind, have maintained simple rain/snow wording without getting too specific in the weather type. Deterministic consensus brings in precipitation on the front side of the approaching surface low Saturday evening into night with gradual cyclogenesis over southern coastal New England Sunday. One can expect mixed precipitation and/or rain to occur during this transition phase into Sunday, depending on how much additional warm air can be wrapped up in the low/mid-level circulation. Also contingent on this is the amount of FGEN forcing and resultant Quantitative Precipitation Forecast we could see out of the system. There is potential for around 1.5" of Quantitative Precipitation Forecast, likely centered over the coastal plain aided by coastal cyclogenesis, but with a sharp cutoff to the north. The low pressure exits east offshore toward the maritimes by Sunday night.

Northwest flow looks to dominate behind the departing trough into the early part of next week, however warm mid-level air lofted north by the prior system remains with temperatures still slated to run at or above normal with another ridge moving in by mid-week. Stuck close to an operational blend of models with weekend system uncertainty likely to impact conditions early next week. The amplified pattern continues through the foreseeable future.

Marine
Short Term
Winds and seas will remain below SCA (Small Craft Advisory) thresholds through Thursday.

Long Term...Smooth sailing for the end of the work week, then a possibly impactful system crosses near the Gulf of Maine during the second half of the weekend. A period of onshore flow could be strong depending on how quickly the low pressure organizes along the New England coast. Current modeled guidance indicates building seas (to 10+ ft) and winds (to SCAs, possibly gales) Saturday into Sunday, peaking Sunday morning. Stronger solutions lead to some minor splash- over but there remains plenty of uncertainty with the specifics of the system.

Hydrology
Rivers that had ice issues the last few days have gone down during the last 24 hours.

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