textproduct: Boston / Norton

WHAT HAS CHANGED

There is potential for elevated fire risk on Thursday, otherwise the general forecast trends remain unchanged.

KEY MESSAGES

- Chilly temperatures tonight will be followed by a period of dry/quiet weather ahead of our next chance for showers Tuesday night into Wednesday

- Shower chances for Wednesday, followed by more seasonable temperatures Thursday through the upcoming weekend. Risk for elevated fire weather concerns Thursday due to low relative humidly and gusty northwest winds.

DISCUSSION

KEY MESSAGE 1...Chilly temperatures tonight will be followed by a period of dry/quiet weather ahead of our next chance for showers Tuesday night into Wednesday.

Short-wave energy moving over southern New England this afternoon ejects southeast overnight bringing an end to any afternoon showers. Northwest flow follows with moderate low-level CAA that will bring 925 hPa temps down to -5C. Additionally, with light winds and clear skies, we can expect a chilly night with well below normal temperatures in the upper 20s to low 30s for much of southern New England. Locations across the interior Northwest may even observe temperatures in the high teens.

A mid-level ridge builds in from the west tomorrow afternoon which will bring 925 hPa temps up closer to 0C. This will support a second consecutive afternoon with high temperatures peaking in the low 50s. Overall a dry and sunny Tuesday dominated by surface high pressure.

As surface high pressure shifts east tomorrow night into Wednesday, return flow and warm advection from the south may support a few isolated to scattered showers across southern New England.

KEY MESSAGE 2...Shower chances for Wednesday, followed by more seasonable temperatures Thursday through the upcoming weekend. Risk for elevated fire weather concerns Thursday due to low relative humidly and gusty northwest winds.

There are no significant weather events on the horizon for Wednesday through this upcoming weekend, a few nuisance hiccups at best. There is a weak system passing through early Wednesday, this is associated with an 850mb shortwave, leading to showery activity. Given marginal temperatures aloft, 925-850mb, between -2C to +2C, cannot rule out a few of the showers containing wet snow. No impacts expected due to the recent warmth. However, a coating isn't out of the question for northern Berkshires and northern Worcester Hills. Otherwise, mostly dry period of weather for the rest of the work week and increasing temperatures. As mentioned by the previous forecaster, 925mb temps rebound to +5C to +8C for Thursday and Friday, returning afternoon highs to the lower 50s and upper 50s. Nightly lows are seasonable in the lower 40s and upper 30s.

Thursday shows potential for elevated risk for fires to spread. The key factors include a mixed boundary layer, leading to low dewpoints/humidity, and gusty NW wind around 20-30 mph. Will need to monitor and collaborate with state officials on whether or not a Special Weather Statement would be needed.

Looking ahead to the weekend, SNE is placed on the western side of a mid-level trough, under NW flow. Shortwave energy does pass through the flow, this may lead to instances of showers, though a washout is not expected at this time. There isn't much of a deviation in 925mb temperatures for the weekend, but added cloud cover, highs could be a few degrees cooler Saturday and Sunday in the upper 50s to 60F.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

18Z TAF Update:

Through 00Z...High Confidence

VFR with -SHRA through 20-21Z. West/northwest winds from 5 to 10 knots.

Tonight...High confidence.

VFR. Skies becoming clear, NW wind becomes NNW to N 5-10 kts and lighter heading into Tue AM.

Tuesday...High confidence.

VFR. Light NNE east winds to start 5-10kts, becoming light SW for interior terminals in afternoon. It may stay more light easterly for the east coast terminals (BOS, Cape/Islands).

KBOS Terminal...High Confidence in TAF. Sea-breeze tomorrow between 15-16Z.

KBDL Terminal... High Confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday: Mainly VFR, with local IFR possible. Slight chance SHRA.

Wednesday Night: Mainly VFR, with local MVFR possible.

Thursday: VFR. Breezy.

Thursday Night through Friday: VFR.

Friday Night through Saturday: VFR. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

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

Tonight through Tomorrow Night

High pressure moves over the coastal waters tonight through tomorrow bringing relatively calm conditions to the coastal waters. Generally expect seas with significant wave heights 3 feet or less and modest wind speeds around 10 knots with some gusts to 15 knots possible. Winds will be out of the north tonight and tomorrow before a shift to southerly flow tomorrow night.

Outlook /Wednesday through Saturday/...

Wednesday through Wednesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.

Thursday Night through Friday Night: Winds less than 25 kt.

Saturday: Winds less than 25 kt. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...None.