textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes have been made to the forecast. Some interior rain showers very late tonight, but any snow showers confined to the very highest terrain. Relatively mild conditions today, and especially Wednesday, with sharply colder weather arriving later Thursday into Friday behind a strong cold front. While a significant storm appears unlikely Saturday night into Sunday, a bit of snow is certainly possible.

KEY MESSAGES

- Overall quiet weather today, followed by a period of showers late tonight across interior southern New England with some snow showers confined to the very highest terrain.

- Mild weather Wed into Wed night with a few rain showers perhaps ending as a brief period of light snow showers early Thu across the interior. Highs Wed in the 40s to near 50.

- Turning colder Thu with falling daytime temps. Dry & cold Thu night-Fri. Lows Thu night in the upper single digits & teens with highs Fri mainly in the upper 20s and lower 30s.

- Milder high temps into the 40s Sat with perhaps a bit of snow sometime Sat night-Sun...but a significant storm is unlikely.

DISCUSSION

KEY MESSAGE 1...Overall quiet weather today, followed by a period of showers late tonight across interior southern New England with some snow showers confined to the very highest terrain.

A series of shortwaves quickly move from west to east tonight along zonal flow. First disturbance passes with little impacts outside of an increase in mid and high level clouds this morning across northern MA. Milder day follows as a transient ridge axis develops over New England. Latest guidance still shows a milder day on tap as 925mb temps climb to 0- 2C. A more amplified shortwave digs over the Great Lakes later Tuesday into Tuesday night. First sign of its approach will be increasing mid and high level clouds later today. Should see a broken band of precipitation pass through the CWA with the higher chances located across northern Massachusetts. Much of the forcing with this shortwave will be confined to Northern New England and so shower activity will be limited in coverage and intensity. May also see a few flakes mix in across the higher terrain but accumulations if any will be light with marginal temperatures and modest QPF.

KEY MESSAGE 2...Mild weather Wed into Wed night with a few rain showers perhaps ending as a brief period of light snow showers early Thu across the interior. Highs Wed in the 40s to near 50.

An amplifying shortwave trough moves across the Great Lakes and into northern New England Wed into early Thu. Out ahead of this cold front/amplifying shortwave trough, southerly flow will result in unseasonably mild temperatures. Despite considerable clouds, high temps will be well into the 40s to near 50 in a few spots. These readings are a solid 10+ degrees above normal for mid January standards.

Given the bulk of the dynamics passing to our north, not expecting a lot of precipitation and much of this time will feature dry weather. Nonetheless, a few showers will be possible at times Wed into Wed night with the focus for them across interior southern New England closer to the shortwave energy. As colder air begins to work in from the west, may see precipitation end as a brief period of light snow showers across interior southern New England early Thu morning. Any snow accumulations should be a dusting to generally less than 1 inch.

KEY MESSAGE 3...Turning colder Thu with falling daytime temps. Dry & cold Thu night-Fri. Lows Thu night in the upper single digits & teens with highs Fri mainly in the upper 20s and lower 30s.

Low pressure will rapidly intensifies Thu into Thu night as it tracks northeast from northern new England into the Canadian Maritimes. The result will be a shot of much colder air working into southern new England Thu into Fri. Temps on Thu will likely fall during the afternoon into the upper 20s and 30s on a stiff gusty west wind. Low temps Thu night will drop into the upper single digits and teens. Wind chills will drop to between 5 below and 10 above by daybreak Fri. High temps on Fri will only recover into the upper 20s and lower 30s. High pressure building in from the west will keep our weather dry, despite the cold conditions.

KEY MESSAGE 4...Milder high temps into the 40s Sat with perhaps a bit of snow sometime Sat night-Sun...but a significant storm is unlikely.

High pressure quickly moves east of the mid-Atlantic coast to start this weekend as another trough gets carved out across the Great Lakes. This allows for a quick rebound in temperatures with highs mainly in the 40s on Sat. The forecast then becomes quite complex Sat night into Sunday with an amplifying trough to our west with several pieces of shortwave energy. The problem is that the guidance is struggling on which piece of energy to amplify and where the actual surface low develops. Latest guidance tends to develop the main surface low too far north and late for a significant storm. That being said, there are a few pieces of guidance including the CMC/ICON that have a wave of low pressure further south with the potential for an inverted trough setup. So while a significant storm appears unlikely, given the amount of shortwave energy to our west we cannot rule out period of snow sometime Sat night into Sun if an inverted trough sets up. Whether or not this happens remains to be seen, but it is something to watch in the coming days.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

Forecaster Confidence Levels...

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

Through Tonight...High confidence.

Mainly VFR. Very brief MVFR conditions possible across the interior between about 03-09Z in a few brief rain showers. Any snow showers will be confined to the very highest terrain of the Berkshires and northern Worcester Hills and rather short-lived too. Modest LLJ developing will result in periods of SW wind gusts of 20 to 25 knots tonight near and southeast of the I-95 corridor. LLWS included for some terminals given winds at 850 mb on the order of 45 to 55 knots.

Wednesday...High Confidence.

VFR for most. Areas MVFR and local IFR towards the Berkshires during the afternoon. Low risk for some rain showers as well.

Wednesday Night...High Confidence.

Mainly VFR to start across the eastern half of southern New England. Areas MVFR with local IFR across the western half expanding east after midnight. Widespread MVFR with IFR across the higher terrain expected towards the Thursday morning push. Chance of rain showers, with snow showers across the higher terrain of the Worcester Hills and Berkshires. More widespread snow showers possible across the western half of southern New England late.

KBOS Terminal... High confidence in TAF.

KBDL Terminal... High confidence in TAF.

Outlook /Thursday through Saturday/...

Thursday: Mainly VFR, with local MVFR possible. Windy with local gusts up to 30 kt. Slight chance SHRA, slight chance SHSN.

Thursday Night: VFR. Windy with areas of gusts up to 30 kt.

Friday through Friday Night: VFR. Breezy.

Saturday: VFR. Breezy. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

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

High Confidence.

Low pressure moving across southeast Canada will result in an increasing S to SW wind across the waters. Gusts up to 30 kt possible. Rough seas expected to develop across the southern coastal waters as well, so Small Craft Advisories continue. A cold front should approach the waters late Wednesday night.

Outlook /Thursday through Saturday/...

Thursday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft. Chance of rain showers.

Thursday Night: Low risk for gale force winds with gusts up to 35 kt. Areas of rough seas. Freezing spray, slight chance of snow showers.

Friday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 10 ft. Freezing spray.

Friday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 10 ft. Slight chance of rain showers, slight chance of snow showers.

Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 7 PM this evening to 11 AM EST Wednesday for ANZ231>235-237-250-251. Small Craft Advisory until 7 PM EST Wednesday for ANZ254. Small Craft Advisory until 10 PM EST Wednesday for ANZ255-256.