Summary: The jet stream (associated with the full thickness tropospheric front) and its associated surface front continues to meander over the region as it has for the past week. The meridional (north-south) temperature contrast is still relatively weak so the jet stream, as well as any surface lows and associated fronts associated with the jet also remain relatively weak. In addition, the jet stream is oriented in a predominantly zonal (east-west) configuration. Therefore, there has not been enough “waviness” in the jet stream or its associated front to allow for the passage of any strong cold fronts with subsequent strong surface high pressure. As such we have remained under relatively persistent cloud cover with intermittent rain showers since last week. This pattern will continue for the next few days. However, the next two cold fronts will be slightly stronger, with slight amplification in the wave pattern, which should permit the sun to return on Thursday after the passage of the first front and then again on Saturday after the second front passes on Friday. There will be the chance of scattered showers with the passage of the first front near dinner time tomorrow. However, this front is still relatively weak so the showers will not be widespread and any rain that does fall should be quite light. A surface high pressure system will then build in behind the front, clearing skies overnight and through the day Thursday. Despite the sunshine, temperatures will struggle past 50 as cooler and drier air moves in behind the front. In fact, it will feel quite “autumnal”. The second front will move through on Friday. This front will probably only be associated with clouds and not any rainfall as the air in advance of the front will be quite dry. One important note: It appears that as high pressure moves in behind the front Friday night, the sky will clear and winds will be light or calm and the air will be quite dry as dew points drop into the 20s for the first time this fall. This will set up ideal radiational cooling conditions overnight that could result in our first widespread frost and, possibly, even a light freeze as temperatures fall into the upper 20s countywide. I will provide more information on this developing situation in tomorrow’s forecast.

Tuesday Night

Remaining mostly cloudy and cool.

Temperatures will not drop much with the cloud cover. Low temperatures should fall to the mid 40s countywide.

Calm winds.

Wednesday

Mostly cloudy. There is the chance of scattered light rain showers late afternoon to early evening with the passage of the cold front. There will be a band of light showers moving through Berkshire County with this frontal passage but it should be broken, not a solid band, so that only some portions of the county will receive any rain. The probability that any one location will receive rainfall is approximately 50%. Any rain that does fall should total less than 0.10 inches.

Despite the cloud cover, it should be slightly milder than on Tuesday as winds shift to the southwest in advance of the front during the afternoon. High temperatures are expected to be in the mid to upper 50s for most of the county with some readings around 60 in portions of South County. If any sun breaks through the temperatures could approach 60 everywhere.

Southeast winds shifting to southwest at 8-12 mph in the afternoon.

Wednesday Night

Mostly cloudy early with the chance of an early evening shower (see daytime forecast). Clearing skies after midnight, becoming breezy and cooler.

Low temperature in the upper 30s.

West-northwesterly winds at 10-15 mph.

Thursday

Partly cloudy (25-50% cloud cover) for most of the day, becoming mostly sunny (<25% cloud cover) later in the afternoon. Breezy and cool.

High temperatures in the low 50s for most of the county including Pittsfield and North Adams, with upper 40s over elevated terrain and in the hilltowns. Highs will likely reach the mid 50s in parts of south county, such as in Great Barrington and Sheffield.

West- northwest winds at 10-20 mph.