Waltham, MA 02454 Weather

What Has Changed

No meaningful changes to the forecast as quiet weather takes hold of the region. Refinements to marine headlines, downgrading Gale Warnings to Small Craft Advisories as Post-Tropical Cyclone Josephine moves east and south of Nova Scotia and New Brunswick today into tomorrow.

Key Messages

- Dry weather continues through the weekend and much of next week. Cool today, with moderating afternoon temperatures this weekend, though chilly mornings will bring widespread frost to much of the area away from the immediate coast.

Discussion

KEY MESSAGE 1...Dry weather continues through the weekend and much of next week. Cool today, with afternoon temperatures gradually moderating this weekend, though chilly mornings will bring widespread frost to much of the area away from the immediate coast.

As anticipated, Subtropical Storm Josephine has undergone extratropical transition, now Post-Tropical Cyclone Josephine per the National Hurricane Center. This system is moving east and will pass to the south of Nova Scotia and New Brunswick Friday into Saturday. With the center of the system moving further east into the North Atlantic Ocean, expansive high pressure builds across the Northeast. Thus, any lingering gusts of 20 to 30 mph will be confined to the easternmost waters and adjacent coastal areas, particularly from Cape Ann to Cape Cod and the Islands. Winds diminish late this morning into the afternoon, while areas farther inland will be treated to a pleasant day with light northerly winds of 5 to 10 mph. Full sunshine today with highs ranging from the lower to middle 50s.

Looking ahead, there really isn't any sensible weather to discuss as the aforementioned high pressure system remains the dominant weather feature for the foreseeable future. However, a weak cold front starved of moisture approaches from the north-northwest on Tuesday. Strong high pressure and dry air will likely cause this front to dry out before reaching southern New England, perhaps adding some cloud cover at most. In fact, global ensembles paint a rather parched picture for southern New England, with probabilities of measurable precipitation (0.01 inches or greater) generally less than 10 percent from Friday through Wednesday of next week.

In terms of temperatures, expect moderating afternoon temperatures this weekend, returning to the upper 50s/lower 60s on Saturday and low to middle 60s on Sunday and Monday. Saturday and Sunday mornings will be quite cold, with lows dropping into the 20s to lower 30s and widespread frost likely away from the immediate coast. Be sure to protect those mums and Halloween pumpkins! Opted to trend overnight lows below NBM guidance, which tends to run too warm during efficient radiational cooling setups, especially with clear skies, calm winds, and strong 1030+ mb surface high pressure overhead. Tuesday into the upcoming week seasonable temperatures day and night are expected.

Aviation

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

12Z TAF Update:

Today through Saturday...High confidence.

VFR conditions prevail through the period. N to NNE winds 10 to 15 kt, gusting 20 to 30 kt today at eastern terminals. Farther inland, N winds around 10 kt. Gusty winds gradually diminish between 00Z and 04Z tonight, with winds generally 5 to 10 kt overnight. Some interior terminals may become calm as high pressure settles in. By Saturday, light W to WNW winds of 4 to 8 kt are expected.

KBOS Terminal...High confidence in TAF.