Casco Bay Marine Forecast
| Tonight...W Winds Around 5 Kt. Seas Around 2 Ft This Evening, Then 1 Foot Or Less. A Chance Of Showers With Isolated Tstms Early This Evening. Patchy Fog Towards Daybreak. Vsby 1 To 3 Nm Towards Daybreak. |
| Mon...W Winds Around 5 Kt, Becoming S In The Afternoon. Seas 1 Foot Or Less, Then Around 2 Ft In The Afternoon. A Chance Of Rain In The Afternoon. |
| Mon Night...Se Winds 5 To 10 Kt, Increasing To 10 To 15 Kt With Gusts Up To 20 Kt After Midnight. Seas Around 2 Ft. Rain. Patchy Fog After Midnight With Vsby 1 To 3 Nm. |
| Tue...S Winds 10 To 15 Kt With Gusts Up To 20 Kt, Becoming Nw 5 To 10 Kt In The Afternoon. Seas Around 2 Ft. Patchy Fog In The Morning. Rain In The Morning, Then Showers Likely In The Afternoon. Vsby 1 To 3 Nm In The Morning. |
| Tue Night...W Winds Around 5 Kt. Seas Around 2 Ft. A Chance Of Showers In The Evening. Patchy Fog After Midnight. |
| Wed...W Winds 5 To 10 Kt. Seas 2 To 3 Ft. Patchy Fog In The Morning. |
| Wed Night...W Winds 5 To 10 Kt, Becoming Nw After Midnight. Seas 2 To 3 Ft. |
| Thu...Ne Winds Around 5 Kt, Becoming Se In The Afternoon. Seas Around 2 Ft. |
| Thu Night...Se Winds 5 To 10 Kt. Seas Around 2 Ft. A Chance Of Showers After Midnight. |
| Fri...S Winds 5 To 10 Kt, Increasing To 10 To 15 Kt With Gusts Up To 20 Kt In The Afternoon. Seas 2 To 3 Ft. Showers Likely. |
| Fri Night...S Winds 10 To 15 Kt With Gusts Up To 20 Kt, Becoming Sw 5 To 10 Kt After Midnight. Seas 2 To 3 Ft. Showers Likely, Mainly In The Evening. Winds And Seas Higher In And Near Tstms. |
| Area Forecast Discussion National Weather Service Gray ME 905pm EDT Sunday Jun 21 2026 .WHAT HAS CHANGED... Rainfall amounts have trended upwards for the late Monday into Tuesday system. These trends will have to be watched closely for potential flood risks. .KEY MESSAGES... 1. Scattered showers and storms diminish by sunset this evening. Slow moving storms have produced heavy rainfall and a localized risk for flash flooding. 2. Low pressure crosses late Monday into Tuesday morning bringing widespread rainfall. A swath of heavy rainfall is possible with this system bringing the risk of flooding. 3. Weather is likely to remain unsettled through the rest of next week. KEY MESSAGE 1 DESCRIPTION... Latest radar shows scattered thunderstorms across Maine and New Hampshire with these storms having a history of producing rainfall rates of 1-2 inches per hour. Ample CAPE across the area has allowed for some stronger cells to contain small hail while the lack of shear has largely keep storms sub-severe. Scattered storms will continue into this evening and will wane with the loss of heating. The primary hazard with these storms will be localized heavy rainfall and possibly the need for additional flash flood warnings. KEY MESSAGE 2 DESCRIPTION... Mesoscale models are in decent agreement in an area of low pressure tracking across southern New England late Monday into Tuesday morning bringing a swath of moderate to heavy rainfall across the area. On the other hand, global models and their ensembles (mainly the GEFS) still have several members that keep the heaviest rainfall to the south of the forecast area. These southern track ensemble members are likely holding down the NBM Quantitative Precipitation Forecast forecast and could see rainfall amounts trend higher over the next forecast cycle if the agreement amongst mesoscale models continues. The synoptic setup is not overly impressive with a low amplitude wave emerging from the Ohio Valley that partially phases with an upper low over SE Canada. There is a signal for the right entrance region of the upper jet to be near by and this could aid in synoptic ascent. Most model solutions bring a plume of PWATs (Precipitable Waters) nearing 1.75 inches across souther areas with PWATs (Precipitable Waters) greater than 2 inches close by. Ultimately, the variability in rainfall amounts will hinge on how far north the low tracks that will allow for higher PWATs (Precipitable Waters) into the area along with better instability. Warm cloud depths nearing 12kFT will also aid in rainfall efficiency. The latest HREF does raise some concerns the mean Quantitative Precipitation Forecast of 2-3 inches across central NH into the White Mountains extending into the foothills of western Maine. The HREF max Quantitative Precipitation Forecast brings amounts up to 5 inches in these same areas. Therefore, stay tune to the latest forecast updates because these higher end amounts will likely warrant a Flood Watch. Low pressure exits Tuesday late Tuesday morning with a drying trend into Tuesday afternoon. KEY MESSAGE 3 DESCRIPTION... A relatively zonal mid-level pattern is likely through the end of this week. This will allow for the potential to see routine bouts of unsettled weather by Thursday and Friday across northern New England. Through the second half of the week, instability over the area is likely to generate scattered showers and thunderstorms. Temperatures also look a little warmer, with high temperatures in the upper 70s and lower 80s through the rest of the week. Wednesday has the best chance to be the driest day of the three, with scattered thunderstorms appearing more likely for Thursday and Friday. Marine Winds and seas remain below SCA (Small Craft Advisory) thresholds through Monday. Low pressure crossing southern New England will bring increasing south winds approaching 25 kts Tuesday morning. Winds shift offshore Tuesday afternoon with winds and seas largely remaining below SCA (Small Craft Advisory) thresholds through late week. NOAA Gray/Portland ME Office - Watches - Warnings - Advisories ME...None. NH...None. Marine None. |
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