Penobscot Bay Marine Forecast
| Rest Of Today...S Winds 5 To 10 Kt. Seas Around 2 Ft. A Slight Chance Of Showers Late This Morning. Patchy Fog Late This Morning With Vsby 1 To 3 Nm. |
| Tonight...S Winds 5 To 10 Kt. Seas Around 2 Ft. Areas Of Fog. Vsby 1 To 3 Nm. |
| Thu...S Winds 5 To 10 Kt. Seas Around 2 Ft. Areas Of Fog In The Morning, Then Patchy Fog In The Afternoon. Vsby 1 Nm Or Less. |
| Thu Night...Sw Winds 5 To 10 Kt, Becoming W With Gusts Up To 20 Kt After Midnight. Seas 2 To 3 Ft. Patchy Fog In The Evening. A Chance Of Showers. Vsby 1 Nm Or Less In The Evening. |
| Fri...W Winds Around 10 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft. |
| Fri Night...Nw Winds 5 To 10 Kt. Seas 2 To 3 Ft. |
| Sat...Sw Winds 5 To 10 Kt. Seas 2 To 3 Ft. |
| Sat Night...S Winds 5 To 10 Kt. Seas Around 2 Ft. |
| Sun...S Winds 5 To 10 Kt. Seas Around 2 Ft. |
| Sun Night...Sw Winds 5 To 10 Kt. Seas Around 2 Ft. |
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Area Forecast Discussion National Weather Service Gray ME 931am EDT Wednesday Jun 18 2025 Synopsis Warmer temperatures are expected today along with a chance of late afternoon showers and thunderstorms north of the mountains. A cold front approaches on Thursday with higher chances for showers and thunderstorms, some of which could be strong to severe. Friday and the weekend will be drier but a few showers or thunderstorms cannot be ruled out. Hot and humid conditions will then return early next week. Near Term - Until 6pm This Evening 930 AMForecast remains on track, with minimal changes needed at this time. Blended in some of the most recent HRRR (High-Resolution Rapid Refresh) to the temperatures, cloud cover, and refreshed forecast to match observations and satellite imagery. 630am Minor changes to reflect latest observational trends. Latest radar trends suggest that the shower activity may linger over southern regions through a large portion of the morning hours though, perhaps a bit longer than some hi-res guidance indicates. Previously... Nighttime microphysics and water vapor satellite imagery early this Wednesday morning shows a plethora of cloud cover across the region with ASOS/AWOS reports indicating widespread low- level stratus. Patchy fog is resulting in reduced visibility and this will continue to be possible through this morning. Northeast radar mosaic continues to show some weak returns streaming northeastward and this is associated with scattered light showers. Latest hi-res guidance indicates these showers should wane over the coming hours but could linger through around 8am over southern areas. Current temperatures are primarily into the 60s and little in the way of additional cooling is anticipated through sunrise. A weak triple point over southern Quebec will send a surface warm front northward today before it stalls over western ME late today. This will result in WAA (Warm Air Advection - the movement of warm air) aloft while low-level southerly flow will persist. Skies will be mostly cloudy but a few breaks of sun are possible late day, especially over western NH. Much of the day should be dry south of the mountains but a few showers and perhaps rumble of thunder is possible across mainly the far north and the mountains themselves. High temperatures will be around 5-10 degrees warmer than yesterday with readings into the 70s to near 80 across the interior with 60s/70s along the coast and towards Penobscot Bay. Short Term - 6pm This Evening Through 6pm Thursday The warm front will retreat southward a bit tonight with cloudy conditions continuing along with patchy fog and low ceilings. A few isolated showers are possible overnight, especially over the north and mountains. Low temperatures will mostly be into the 60s. A deep mid-level trough axis will move from the Great Lakes region and southern Quebec on Thursday before arriving in New England during the afternoon and evening. At the surface, closed low pressure will arrive from the west and in doing so will send a surface warm front northward early in the day, which will then be followed by a trailing cold front late day. This will place our region within the warm sector with southerly flow allowing for deep moisture transport. After a cloudy start to the day increasing sunshine is expected during the afternoon, sending high temperatures into the lower 90s in southern NH with middle to upper 80s further to the north and extending into southwestern ME. Further to the east, highs into the 60s and 70s are expected from the Capital District and point east. These warm temperatures combined with dew points nearing 70F will likely allow for strong destabilization to occur. There is an increasing threat for strong to severe thunderstorms during the afternoon and early evening hours. Forecast soundings show MUCAPE between 2,000-3,000 J/KG during the afternoon with 0-6km bulk shear between 30-40 kts. Low-level lapse rates are forecast to reach up to around 7C/km with 700-500mb lapse rates a little less conducive for severe storms but still respectable for our area at around 6C/km. Latest forecast hodographs show the potential for a few discrete supercells along with perhaps some linear segments to develop. These parameters combined with precipitation loading with PWATs (Precipitable Waters) approaching and perhaps exceeding 1.50" introduces the threat for damaging winds along with severe hail given the high shear profiles. While not the greatest of the threats, an isolated tornado cannot be ruled out given the high 0-1km shear and SRH and high 0-3km CAPE profiles and low LCL heights. The latest SPC D2 outlook places most of the area now in a SLGT risk (2/5) with all severe threats on the table. A MRGL (1/5) risk exists for the coast and Mid-Coast region where later clearing and onshore flow introduces an overall lower risk. Isolated flash flooding is also possible given deep warm cloud depths and high PWATs. Long Term - Thursday Night Through Tuesday 12am Long TermLoaded latest med-long term guidance while preserving prev forecast shift's thoughts. This mainly includes a breezy Friday morning. Passing jet will be moving through the region late Thursday night/Friday morning, and when daytime mixing kicks in amid cooler and drier NW flow, gusts could climb towards 30 mph. This does weaken into the afternoon, with daytime highs around 10 degrees cooler than Thursday. Brought Probability of Precipitation down a bit for the day Friday. While there will be good heating, profiles are quite dry to produce more than isolated showers on the day. No change in thinking ahead of a more prolonged (relative to this week) warmup early next week. ECMWF (European Centre for Medium-Range Weather Forecasts) EFI continues to highlight a broad region of warmer temps vs. seasonal reforecasts. There are hints of increasing shift of tail values, but not uniform enough to go higher than forecast guidance at this range. Friday is a little less certain with some guidance showing a quicker frontal passage while others suggest a slower passage with perhaps another weak low developing along it. The faster solution would result in a drier/breezier day on Friday while the slower solution keeping more clouds/showers a little longer. However, even with the slower solution, it could still get pretty breezy across western areas. For the weekend, a strong 500mb ridge builds across the Deep South and toward the Great Lakes, which will gradually expand toward the East Coast. New England will be on the eastern periphery of this ridge with a couple of disturbances possibly riding along it to bring an opportunity or two for showers and storms over the weekend, although confidence in timing and location remains lower. Temperatures remain warm across much of the interior with temps well into the 80s possible by Sunday. Of higher confidence is the heat and humidity set for early next week with strong ensemble support for anomalously warm temperatures aloft as the ridge further expands. The combination of hot temperatures and humidity could produce heat index values in the mid to upper 90s. Marine Short Term Southerly onshore flow will continue as a warm front stalls near the waters today into tonight. Marine and coastal fog will be common. A cold front will approach the waters late tomorrow with scattered showers and thunderstorms possible. Otherwise, winds and seas below SCA (Small Craft Advisory) thresholds are expected. Long Term High pressure builds in south of the waters over the weekend with another weak low pressure/front possibly moving through at some point. However, timing and location is uncertain, but it looks like conditions will stay below SCA (Small Craft Advisory) levels over the weekend. For early next week, broad high pressure becomes established over the eastern CONUS and into western Atlantic with south to southwest flow over the waters. NOAA Gray/Portland ME Office - Watches - Warnings - Advisories ME...None. NH...None. Marine None. |
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