Summary: The change in the jet stream pattern which had been anticipated last week is presently taking place. Unfortunately, this change is stuck in transition directly over our region. A large southward plunge in the jet stream wave pattern (trough) over the Western U.S. has brought some rain to California and snow to the Rockies with much cooler temperatures. In response, the jet stream wave pattern has lifted to the north (ridge) over the Eastern U.S.. This is bringing much warmer temperatures to the Midwest and most of the East Coast. Temperatures have surged into the unseasonable 70s and 80s. Unfortunately, the trough which is lifting out of our region is taking its sweet time and, effectively, is blocking the northward surge of the ridge. So, we are caught between the trough and the ridge which is manifested as a surface warm front which is stalling just to the southwest of Berkshire County. The lighter warm air (80 degrees in Pittsburgh!!) is trying to advance north but is unable to budge the heavier cooler air over New England (temps in the 50s), so it is riding up over it, causing cloud formation and a band of rain and showers to develop today. As the front stalls, we will be stuck in the clouds, with relatively cool and moist air (temperatures still are slightly above normal for this time of year) for the next 48 hours or so. Hopefully, the front will finally push through to our northeast later on Thursday. This should allow at least some sunshine and warmer temperatures to move in for Friday and Saturday. In fact, temperatures could crack the 70 degree mark on both days before a strong cold front moves through late on Saturday. We may actually have below average temperatures early next week, but that is still a long way off.

Tuesday Night

Overcast with showers likely in the evening. Probability of precipitation 90% in South County, 80% in Central Berkshire but only 50% in North County as the northern edge of the precipitation shield associated with the warm front, while giving northern areas some showers this afternoon, will shift south in the evening and may not reach the Vermont border and may even stay south of Williamstown and North Adams during the nighttime hours. Precipitation totals will likely be between 0.10 and 0.25 inches with the heaviest totals to the south. The steadier rain should end near midnight with only a chance of scattered light showers after midnight.

Low temperatures in the low to mid 40s.

Light and variable winds becoming calm.

Wednesday

Overcast and seasonably cool. There may be a few scattered sprinkles and some drizzle but it will be mostly dry.

High temperatures in the mid 50s in Pittsfield and North Adams, upper 50s in Great Barrington and low 50s over elevated terrain and the hilltowns.

Light north-northeasterly winds.

Wednesday Night

Remaining cloudy with a few scattered areas of drizzle or sprinkles.

Low temperatures generally in the mid 40s.

Calm winds.

Thursday

Mostly cloudy. There may be a few peeks of sun later in the afternoon. There may be some lingering drizzle in the morning.

It will remain seasonably cool but will likely be a few degrees warmer than Wednesday with high temperatures in the upper 50s in Pittsfield and North Adams, near 60 in Sheffield and Great Barrington and mid 50s over the elevated terrain and hilltowns.

Southeasterly winds at 5-10 mph.