7:34AM
DAYS 1-5 (NOVEMBER 21-25)
Discussion…
A couple adjustments will be made in this forecast. Giving more weight to the northern jet stream and less to the southern jet stream. I think one of the common difficulties the medium range guidance sets are having is over-forecasting the strength of southern jet energy and mistiming disturbances in the northern stream. So this is the current thinking: A mild west southwest air flow arrives today and boosts temperatures to the plus side of normal, something we have not seen much of this month. But this will be short-lived as a cold front charges eastward with an arrival time of Wednesday morning. While this is ongoing, a plume of moisture that had moved from the Gulf of Mexico to the waters off the US Southeast Coast will get drawn northward ahead of the front. As it starts to curve to the east, it should clip southeastern MA and RI with a period of rain Wednesday morning, but showers associated with the front should dry up as they try to cross the mountains to the west and north of the region. By later Wednesday, colder air will be flowing in and this will set up a dry and chilly Thanksgiving holiday on Thursday. However another frontal boundary will approach from the northwest by late Thursday and some cloudiness will arrive in advance of it. Where I previously thought moisture to the south may fan some cloudiness into the region Thursday/Friday, I no longer feel this will be an issue. However, Friday may still turn out to have more cloudiness from advancing milder air from the west, and this should be here by Saturday for another short-lived stay.
Forecast Details…
TODAY: Sunny. Highs 54-60. Wind WSW 10-20 MPH, gusts 25-35 MPH mainly in the afternoon.
TONIGHT: Increasing clouds. Rain likely Cape Cod and Islands and chance of rain remainder of southeastern MA and RI toward dawn. Lows 42-48. Wind SW to S 5-15 MPH.
WEDNESDAY: Cloudy through mid morning with a chance of rain RI and eastern MA except cloudy through late morning with rain more likely Cape Cod and Islands. Clearing late morning. Sunny afternoon. Highs 45-53 morning, falling through the 40s afternoon. Wind SW 5-15 MPH morning, NW increasing to 10-20 MPH with higher gusts afternoon.
WEDNESDAY NIGHT: Clear. Lows 22-32, coldest interior valleys, mildest coastline. Wind NW 10-20 MPH early, diminishing overnight.
THURSDAY – THANKSGIVING: Mostly sunny morning. Partly sunny afternoon. Highs 38-45. Wind light variable.
FRIDAY: Variably cloudy. Slight risk of brief very light rain NH/MA. Lows in the 30s. Highs in the 40s.
SATURDAY: Partly cloudy. Risk of a rain shower late-day or evening. Lows in the 40s. Highs in the 50s.
DAYS 6-10 (NOVEMBER 26-30)
Transition back to below normal temperatures in the November 26-28 period but I’m not sure yet of the weather details. Not completely letting go of a chance of a storm system the models still don’t see. Faster-flow may allow moderation the last 2 days of the month.
DAYS 11-15 (DECEMBER 1-5)
Low confidence. Fine line between a block and zonal pattern as we have talked about. Will re-evaluate but for now leaning toward mild followed by cold with an unsettled period in the transition.