Casco Bay Marine Forecast
|Overnight...S Winds Around 5 Kt, Becoming Se. Seas Around 2 Ft. Areas Of Fog. A Slight Chance Of Showers Late. Vsby 1 To 3 Nm.|
|Fri...E Winds Around 5 Kt. Seas Around 2 Ft. A Chance Of Showers. Areas Of Fog In The Morning. Patchy Fog In The Afternoon. Vsby 1 To 3 Nm.|
|Fri Night...S Winds 5 To 10 Kt. Seas 1 To 2 Ft. Patchy Fog. Vsby Variable To Less Than One Quarter Nm.|
|Sat...S Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft. Patchy Fog In The Morning. Vsby Variable To Less Than One Quarter Nm In The Morning.|
|Sat Night...S Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 4 Ft. A Chance Of Showers. Patchy Fog After Midnight. Vsby Variable To Less Than One Quarter Nm After Midnight.|
|Sun...S Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft. Patchy Fog In The Morning. Vsby Variable To Less Than One Quarter Nm In The Morning.|
|Sun Night...Sw Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft. Patchy Fog After Midnight. Vsby Variable To Less Than One Quarter Nm After Midnight.|
|Mon...Sw Winds 10 To 15 Kt. Seas 2 To 4 Ft. Patchy Fog In The Morning. Vsby Variable To Less Than One Quarter Nm In The Morning.|
|Mon Night...Sw Winds 5 To 10 Kt. Seas 2 To 4 Ft. Patchy Fog After Midnight. Vsby Variable To Less Than One Quarter Nm After Midnight.|
|Tue...Sw Winds 5 To 10 Kt. Seas 2 To 3 Ft. Patchy Fog In The Morning. Vsby Variable To Less Than One Quarter Nm In The Morning.|
|Tue Night...Sw Winds 5 To 10 Kt. Seas 2 To 3 Ft. A Chance Of Showers. Patchy Fog After Midnight. Vsby Variable To Less Than One Quarter Nm After Midnight.|
| Area Forecast Discussion|
National Weather Service Gray ME
1008pm EDT Thu Jun 24 2021
High pressure settles to position south of Nova Scotia tonight with a weak low passing near the coast Friday morning. This will bring scattered showers south of the mountains with a drying trend Friday afternoon. Heat and humidity builds over the weekend into next week with chances for afternoon showers and thunderstorms. Heat indices will peak on Monday into the mid and upper 90s with little signal for a cool down in the long term.
Near Term - Until 6am Friday Morning
1005 PM...Just a few tweaks to temps/sky based on current obs, but overall forecast remains similar for the overnight, with increasing clouds after midnight in the south, and a few showers possible around daybreak.
710 pm...Based on some of the latest meso models and satellite trends, have edge back arrival of low stratus in time, and allowed POPs to follow. This puts chance of showers in southern NH during the pre dawn and daybreak to 12Z slightly further inland in NH and along the ME coastal counties.
Previously...Broad area of high pressure shifts eastward tonight as a weak area of low pressure tracks up the Eastern Seaboard. Cloud cover will increase over southern areas tonight in response to the northward moving low while northern areas will see mostly clear skies. Northern valleys that maintain clear skies will likely see some patchy fog develop tonight while southern and coastal areas will see chances of showers by daybreak. Lows will range from the low 40s north to mid 50s south.
Short Term - 6am Friday Morning Through Friday Night
Area of low pressure will transition to an open wave as it crosses eastern Massachusetts around sunrise. Showers will scrape along southern New Hampshire and the coastal plain of Maine through late morning. CAMs show some elevated instability with PWATs (Precipitable Waters) between 1.25 and 1.5 inches so there may be rumble of thunder and some showers will be capable of producing moderate rainfall. Overall expectations are for coastal areas pick up less than a tenth of inch with some local amounts to a quarter of an inch of rain. Showers will taper off late morning with some lingering showers into the afternoon near the Mid-Coast. Skies will be mostly cloudy across southern New Hampshire and south of the mountains in Maine with more sun in the north. This will lead to the Connecticut Valley into northwest Maine being the warm spots withs highs near 80 with mid 70s across the interior and low 70s near the coast where the cloud deck will limit solar insolation.
Partly to mostly cloudy skies are expected Friday night with lows in the mid 50s north to mid 60s south.
Long Term - Saturday Through Thursday
Much above Normal Temperatures Sunday into Wednesday... Overall global models are in good agreement in the long term portion of the forecast. The area will be on the NW periphery of a large upper level area of high pressure with a bermuda high at sea level off the East Coast. This setup will result in increasing temperatures and dewpoints (relative humidity) throughout much of the period. Being on the NW side of this setup does allow for weak disturbances to perhaps set off a few showers and thunderstorms...most of these should be confined over the mountains and near the Canadian border.
In the dailies, Saturday and Saturday Night will be the transition period as a warm front moves through. Some clouds and showers are possible with its passage especially over northern parts of the area. Behind the warm front on Sunday we will be in the warm sector resulting in significantly higher temperatures and dew points with highs reaching the low 90s over many locations. It will be dry with the exception of the mountains where a few airmass showers and thunderstorms are possible. Monday and Tuesday look to be even hotter than Sunday with highs in the mid 90s and apparent temperatures in the upper 90s to near 100. There will be a continued possibility of the chance of a few airmass showers and thunderstorms especially over the highlands and mountains. Low temperatures will be warm as well with reading only reaching lows in the upper 60s and lower 70s south of the mountains. On Wednesday and Thursday temperatures will be a little cooler (upper 80s to lower 90s) with a bit more cloud cover and a better chance of showers and thunderstorms as a weak disturbance moves just to our north.
Have used the NBM as a good starting point but did lower POPS some especially Saturday and Thursday.
Winds and seas remain below SCA (Small Craft Advisory) thresholds through Friday night. Patchy fog is expected over the waters tonight and again Friday night. Weak low pressure passes through the waters tomorrow morning bringing some showers.
Long Term... Outside the bays...wind and waves approaching low SCA (Small Craft Advisory) levels late Saturday and lasting into next week as a persistent south and southwest wind develops. Areas of fog and haze are possible as warm air moves over colder water.
NOAA Gray/Portland ME Office - Watches - Warnings - Advisories
ME...None. NH...None. MARINE...None.