St. John Valley weather for May 27-June 2, 2020
Short-Term Outlook: Wednesday – Friday
A strong upper-ridge anchored off the Southeastern US coast will bring warmer and more humid than normal conditions to the Valley through the late week period.
The upper-level ridge will shift to to the east/northeast and move away from the US through the late week period while the surface high pressure well offshore in the Atlantic will weaken allowing a strong cold front to approach Friday. Moisture is also being channeled northeast from the circulation around an upper-level closed-low over the Lower Mississippi Valley / Southern Plains, and this moisture will provide fuel as a disturbance moves across northern Maine this afternoon. Instability aloft will allow for thunderstorm activity including a marginal risk for some isolated strong to severe thunderstorms across the Valley with large hail and a few strong wind gusts being the primary threat this afternoon. The disturbance will move east of the region this evening with the high-pressure ridge continuing to bring partly cloudy skies tonight and Thursday.
Thursday will be quite hot and humid with temperatures pushing the 90F mark in Fort Kent and surrounding areas. Another weak disturbance is expected to move across the region Thursday afternoon; however, current model runs indicate less robust atmospheric dynamics Thursday afternoon, so only a slight chance for afternoon showers/thunderstorms and thunderstorms is expected.
Clouds will increase Thursday night as a strong cold front approaches from the west ahead of a notably cooler air mass for northern Maine. A warm front ahead of the system will produce a chance for showers after midnight Thursday night with a greater chance for showers and thunderstorms by mid-morning Friday ahead of the main cold front. Showers and thunderstorms are expected to continue Friday afternoon into the overnight hours with a steadier rain, possibly heavy at times, likely as the cold front moves through. Some strong storms may be possible; however, variances in forecast models create some uncertainty regarding any severe weather as of this Wednesday morning.
Today & Tonight
Partly sunny and humid with a 60 percent chance for afternoon/evening showers and thunderstorms. Isolated strong/severe storms are possible with large hail the primary threat across the Valley. Rainfall in the 1/10 to 1/4-inch range expected with higher amounts in any storms. High in the middle 80s with south/southwest winds 0 to 5 mph.
Tonight, partly cloudy with a 20 percent chance for showers and thunderstorms before midnight. Low in the middle 60s with south/southwest winds 0 to 5 mph.
Thursday, May 28
Partly cloudy, hot, and humid with a 20 percent chance for afternoon showers and thunderstorms. High in the upper 80s with west/southwest winds 5 to 10 mph.
Thursday night, partly cloudy with a 20 percent chance for showers after midnight. Low in the mid-60s with southwest winds 0 to 5 mph.
Friday, May 29
Partly sunny with a high in the middle 80s. A 50 percent chance for showers and thunderstorms with some strong storms possible. Rainfall between 1/100 and 1/10-inch with higher totals possible in storms. Southwest winds 5 to 10 mph.
Friday night, partly cloudy with an 80% for rain, showers, and thunderstorms. Low in the low 60s. Southwest winds 0 to 7 mph.
Medium Range: Saturday – Tuesday
The cold front moves through Saturday with rain tapering to showers in the afternoon. A slight chance for afternoon thunderstorms is possible. Showers continue overnight into Sunday morning as the front moves east. Much cooler Sunday as high-pressure centered over the Upper Mississippi Valley/Great Lakes builds east into New England. Skies become partly cloudy Sunday afternoon with a slight chance for shower activity over the course of the day. High-pressure will slide over the Ohio Valley early next week with partly cloudy/mostly clear skies, drier conditions, and below normal temperatures for the SJV. Indeed, some areas of frost may be possible across the region Sunday night and Monday night.
Saturday, May 30
Mostly cloudy with a 60 percent chance for rain tapering to showers along with a slight chance for afternoon thunderstorms. High in the middle 70s with west winds 8 to 14 mph.
Saturday night, partly cloudy with a low in the middle 40s and a 20 percent chance for showers. Northwest winds 0 to 7 mph.
Sunday, May 31
Partly cloudy with a 20 percent chance for showers. High in the upper 50s/low 60s with northwest winds 8 to 14 mph.
Sunday night, partly cloudy to mostly clear with a low in the upper 30s. Slight chance for showers. Northwest winds 0 to 7 mph.
Monday, June 1
Partly cloudy with a slight chance for showers. High in the upper low 60s. Northwest winds 8 to 14 mph.
Partly cloudy with a slight chance for showers. Low in the mid-top-upper 30s. Northwest winds 0 to 7 mph.
Tuesday, June 2
Partly cloudy with a 20% chance for afternoon showers. High in the low 60s with north winds 8 to 14 mph.
Tuesday night, partly cloudy with a slight chance for showers. Low in the upper 30s/low 40s. North/northwest winds 0 to 7 mph.
Regional Long-Range Trends: Wed. June 3 – Tue. June 9
Slightly below normal temperatures and near normal precipitation
Note: Computer model precision diminishes the further into the week the forecast projects. Check the Fiddlehead Focus for weather updates with more current information.
The Week Ahead is the work of UMFK Professor Joseph E. Becker based on personal weather station data, various computer forecast models, and information that the National Weather Service, NOAA, and other weather resources provide.