Short-Term: Wednesday, Aug. 19-Friday, Aug. 21
The next several days will feature limited rainfall, with the best chance for showers and thunderstorms today and Thursday afternoon. Rainfall amounts are expected to be light and highly variable, with many locations receiving little or no measurable precipitation. High pressure building in from the west will bring drier and more seasonable weather heading into the weekend.
A cold front will move toward Maine from Quebec today and Thursday, although it will gradually weaken as it approaches the region. An upper-level disturbance ahead of the front will move through the Saint John Valley today, bringing a chance for afternoon and evening showers and a few thunderstorms, mainly across the Saint John Valley and North Woods. Most areas will remain dry, however, with only a limited chance of measurable rainfall.
Areas of fog this morning will give way to mostly cloudy skies today, with temperatures reaching the upper 70s. Winds will be light, becoming southwest at around 5 to 10 mph this afternoon. Scattered showers and isolated thunderstorms are expected to develop this afternoon, with the greatest potential across northern areas. A few thunderstorms could produce brief heavy rain and gusty winds, but widespread severe weather is not expected. The chance of precipitation will be around 50 percent.
Scattered showers and thunderstorms will continue into this evening before becoming isolated by late evening. Patchy fog will develop overnight as skies remain mostly cloudy. Temperatures will fall into the mid-50s, with light southwest winds. Most locations will receive little rainfall, and many areas will remain dry.
Thursday will be mostly sunny overall, although a few isolated showers and thunderstorms may develop during the afternoon as the weakening front approaches the region. Temperatures will reach the lower to middle 70s, with light northwest winds around 5 mph. The chance of precipitation will be around 20 percent, and most locations will not receive measurable rainfall.
The front will move through Thursday night, followed by clearing skies and the arrival of higher pressure from the west. Areas of fog may develop late Thursday night, with temperatures falling into the upper 40s and winds becoming calm.
Friday will bring a return to dry and mostly sunny weather. Areas of morning fog will dissipate by mid-morning, followed by a pleasant afternoon with temperatures in the lower 70s. Winds will be light early, becoming northwest at around 5 to 10 mph during the afternoon. Mostly clear skies will continue Friday night, although patchy fog may develop toward morning. Overnight temperatures will fall into the middle 40s.
Mid-range: Saturday, Aug. 22-Tuesday, Aug. 25
High pressure will slide across the region Saturday, bringing mostly sunny skies and mild conditions. Patchy fog is possible early in the morning, followed by increasing sunshine and temperatures in the middle to upper 70s. Winds will be light and variable, becoming southerly at around 5 mph during the afternoon. Clouds will increase Saturday night, with temperatures falling into the lower to middle 50s.
A low pressure system will approach from the Great Lakes on Sunday and move into Quebec by Monday, while another area of low pressure tracks along the coast and brings additional moisture into the region. Increasing clouds and a few showers are expected Sunday, with a chance for thunderstorms during the afternoon. Temperatures will reach the lower to middle 70s, with a 70 percent chance of precipitation.
Showers will become more likely Sunday night and continue into Monday as the low pressure system moves through. A few thunderstorms will also be possible, particularly along the frontal boundary. Sunday night will remain mostly cloudy, with temperatures in the middle 50s and a 70 percent chance of precipitation. Monday will feature widespread cloud cover with periods of showers and thunderstorms and temperatures in the lower to middle 70s. Additional showers and thunderstorms will remain possible Monday night, with temperatures falling into the lower to middle 50s.
Rainfall amounts are expected to remain modest overall, although locally heavier rainfall could occur with any thunderstorms or areas of enhanced lift along the frontal boundary. At this time, the system is not expected to provide enough rainfall to significantly improve ongoing drought conditions. Confidence is relatively high that rain will occur Sunday into Monday, but there remains greater uncertainty regarding the total rainfall amounts and the coverage of thunderstorms.
Surface high pressure is expected to build into the region Tuesday and Wednesday, bringing some improvement in conditions. However, upper-level troughing will remain over the area and could produce additional chances for showers. Tuesday will be partly sunny with temperatures in the lower 70s and a 30 percent chance of showers. A few showers could linger into Tuesday evening, although most of the night should remain dry, with temperatures in the lower to middle 50s. Overall, the pattern will remain unsettled into the middle of next week, but widespread rainfall is not currently expected.
Long-range: Wednesday, Aug. 26-Tuesday, Sep. 1
Climate Prediction Center trends indicate near normal temperatures and precipitation for the period. Normal temperatures during the final week of August and first day of September are generally in the upper 60s to lower 70s for highs and around 50°F for lows. The period averages around three-quarters of an inch of precipitation.
Daily Forecast Summary
Today: Mostly cloudy. Areas of fog this morning. Scattered showers with isolated thunderstorms this afternoon. Highs in the mid-70s. Southwest winds around 5 mph. Chance of rain 50 percent.
Tonight: Partly cloudy. Scattered showers with isolated thunderstorms in the evening. Patchy fog in the evening, then areas of fog after midnight. Lows in the mid-50s. Southwest winds around 5 mph. Chance of rain 50 percent.
Thursday: Partly sunny. Areas of fog in the morning. Isolated thunderstorms in the afternoon. Highs in the lower 70s. West winds around 5 mph. Chance of precipitation 20 percent.
Thursday Night: Mostly cloudy in the evening, then clearing. Areas of fog after midnight. Lows in the mid-40s. Northwest winds around 5 mph.
Friday: Areas of fog in the morning. Sunny. Highs in the lower 70s. Northwest winds 5 to 10 mph.
Friday Night: Clear. Patchy fog after midnight. Lows in the mid-40s.
Saturday: Mostly sunny in the morning, then becoming partly sunny. Patchy fog in the morning. Highs in the mid-70s.
Saturday Night: Partly cloudy. Lows in the lower 50s.
Sunday: Partly sunny with a chance of showers in the morning, then mostly cloudy with showers likely in the afternoon. Highs around 70. Chance of rain 70 percent.
Sunday Night: Showers likely, mainly in the evening. Lows in the mid-50s. Chance of rain 70 percent.
Monday: Mostly cloudy. A chance of showers in the morning, then showers likely in the afternoon. Highs in the lower 70s. Chance of rain 70 percent.
Monday Night: Partly cloudy. A chance of showers in the evening. Lows around 50. Chance of rain 50 percent.
Tuesday: Partly sunny. Highs around 70.
Tuesday Night: Partly cloudy. A slight chance of rain showers in the evening. Lows in the lower 50s. Chance of rain is 20 percent.
Weather Notice: The weekly forecast, by UMFK Professor Joseph E. Becker, is based on available computer models and data and may not reflect current conditions or later forecast updates. Check The County.me or the National Weather Service Caribou, Maine for the most recent weather information for the Saint John Valley.
