Yarmouth Port, MA Weather

What Has Changed

No meaningful changes to the forecast, with an extended stretch of quiet and dry weather ahead.

Key Messages

- Prolonged stretch of dry weather across southern New England, likely lasting through Halloween, with a potential transition toward unsettled weather in early November. Mild temperatures today, followed by a brief cooldown Tuesday and Wednesday before warmer weather returns late in the week. Temperatures trend closer to seasonable levels over the weekend.

Discussion

KEY MESSAGE 1...Prolonged stretch of dry weather across southern New England, likely lasting through Halloween, with a potential transition toward unsettled weather in early November. Mild temperatures today, followed by a brief cooldown Tuesday and Wednesday before warmer weather returns late in the week. Temperatures trend closer to seasonable levels over the weekend.

Nearly picture-perfect fall weather continues for the upcoming week across southern New England. Once again, the broken record is playing track one, titled "High Pressure." An extended stretch of dry weather is expected, with some day-to-day variability in temperatures, but otherwise not much excitement on the horizon. In fact, global ensembles paint a rather parched picture for southern New England, with cumulative probabilities of measurable precipitation (0.01 inches or greater) generally less than 10 percent through All Hallows' Eve!

An expansive area of surface high pressure, around 1030 mb, continues to dominate the regional weather pattern, although its center has shifted slightly farther south toward the Mid-Atlantic compared to 24 hours ago. Nevertheless, this will promote plenty of sunshine, light winds, and generally quiet conditions. Two cold fronts will pass through the region this week, albeit moisture- starved cold fronts. The first arrives tonight into early Tuesday, followed by a second Friday night into Saturday morning. However, persistent high pressure and dry air will likely limit these fronts to little more than some additional cloud cover, breezy conditions, and cooler air masses. The next opportunity for precipitation may arrive Sunday or Monday of next week, as global guidance hints at a transition toward a more active weather pattern during the first week of November.

In terms of temperatures, 925 mb temperatures warm to +14C today, supporting highs in the middle 60s to near 70F this afternoon. In the wake of the first moisture-starved cold front, Tuesday will be noticeably cooler, with 925 mb temperatures +1C to +4C. This should support afternoon temperatures roughly 10 to 15 degrees cooler than today, with highs in the lower to middle 50s.

Starting Wednesday, warm air advection aloft leads to a steady increase in temperatures through the remainder of the week, with Wednesday afternoon a few degrees warmer than Tuesday. Thursday and Friday look fairly mild considering the time of year, with highs returning to the middle 60s Thursday and upper 60s to potentially the lower 70s Friday! DESI probabilities of highs reaching 70F or greater Friday have increased significantly over the past 24 hours, from 30 to 50 percent yesterday to generally 60 to 80 percent or higher today, with lower probabilities along the coast and across higher terrain. Unfortunately, this warmth will be short-lived, as the second moisture-starved cold front passes through Friday night into Saturday morning, knocking temperatures back by around 10 degrees. This should bring highs back into the upper 50s to lower 60s over the weekend.

After a frosty weekend, overnight temperatures should trend closer to seasonable levels, generally in the upper 30s and 40s through much of the week. One exception may be Wednesday morning, when a cooler post-frontal air mass, combined with light winds and mainly clear skies, could allow for efficient radiational cooling and temperatures to fall back into the 20s and lower 30s. However, urban areas such as Boston will likely remain above freezing, with lows in the middle to upper 30s. Confidence in the colder temperatures Wednesday morning remains moderate given uncertainty regarding how effectively winds decouple overnight, which could limit radiational cooling. Be sure to protect those mums and Halloween pumpkins!

Aviation

Forecaster Confidence Levels...

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

18Z TAF Update:

Today and Tonight...High confidence.

VFR conditions. W to WNW winds this afternoon at 6-12 kts. Occasional gusts of 18-20 kts possible for Cape/Islands. A cold front pushes through the region between 00-04Z. No rain expected; however, this will bring a windshift to the NW/NNW with gusts 18-25 kts. Highest gusts for Cape and Islands. SCT to BKN cloud decks accompany the front, but likely to be mid-level (050-100).

Tuesday...High confidence.