textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes made to the forecast.

KEY MESSAGES

- Quiet weather continues through Tue night with highs mainly in the 60s to 70+ in the CT Valley...But only 50s along the immediate coast. Lows in the 30s to the lower 40s.

- Unsettled weather returns late Wednesday and Thursday with a soaking rain likely.

- Remains unsettled Friday into the weekend with cooler than normal temperatures. Isolated showers possible.

DISCUSSION

KEY MESSAGE 1...Quiet weather continues through Tue night with highs mainly in the 60s to 70+ in the CT Valley...But only 50s along the immediate coast. Lows in the 30s to the lower 40s.

A ridge of high pressure will remain in control of our weather through Tue night. This high pressure system will result in mainly clear skies tonight with another excellent night of radiational cooling. Low temps will drop well down into the 30s across the many of our locations...to the lower 40s in some of the urban centers. Airmass is still quite dry...But can not rule out some patches of fog/low clouds developing overnight near the coast. Low confidence on whether or not this happens...but greatest risk towards the Cape and Islands.

Plenty of sunshine is expected on Tue...Although do expect some mid- high level cloudiness to overspread the region during the day. Onshore flow a bit stronger than today...so high temps probably a few degrees lower than today on the coastal plain. Nonetheless...still expect highs to reach into the 60s in most locations away from the immediate coast. The mild spots will again be the CT Valley where high temps of 70+ seem likely. Meanwhile...onshore flow will hold high temps mainly in the lower to middle 50s along the immediate coast, Cape and Islands.

Mainly dry and cool again Tue night with another good night of radiational cooling. Lows will be in the 30s in many locations with lower 40s in most urban centers. We will need to watch for some stratus and perhaps some fog patches working in off the ocean into eastern MA/Cape overnight. Perhaps even a touch of spotty drizzle/very light showers working in off the ocean too.

KEY MESSAGE 2...Unsettled weather returns late Wednesday and Thursday with a soaking rain likely.

Wednesday will be a "transition" day as the weather pattern becomes unsettled by Thursday morning. Most places remain dry for Wednesday with high pressure in place. As a trough approaches from the west, moisture begins to advect into the region mainly from the west. Expect cloudy skies for the day with continued NE flow. Only areas that may see an isolated shower or two are the eastern coastal areas.

The shortwave trough and frontal system arrive overnight Wednesday into Thursday. Precipitable water values rise to around 1.0", supportive of widespread showers/rain. Model guidance is still a little split in the details, especially with the development of a secondary low pressure that tracks around/just offshore of the Cape Thursday. This may have some influence on rain amounts as well as the wind direction/speed. We are still continuing to monitor coastal flooding, but even minor coastal appears very low probability at this point for the eastern coastal areas. The bulk of the rain exits Thursday night. Most places should get at at least a half an inch. There are some low probabilities for around 1" of rain for northeast MA.

KEY MESSAGE 3...Remains unsettled Friday into the weekend with cooler than normal temperatures. Isolated showers possible.

Weather pattern remains unsettled Friday through the weekend with troughing aloft. This will bring cooler than normal temperatures and partly to mostly cloudy skies overall. Can't rule out pop-up showers on Friday into the weekend underneath the trough/cyclonic flow aloft. There is some marginal instability present, so can't rule out a graupel within any showers. There is a small percent of model/ensemble guidance that indicates the potential for a coastal system to give a glancing blow to southern new england over the weekend. In this scenario this could bring rain/gusty winds later Saturday into Sunday to portions of southern new england. Again, this is still low probability scenario right now being displayed by a small percentage of model solutions. This will continue to be monitor as confidence in the upper pattern and details increases as we get closer.

AVIATION /00Z TUESDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

00z TAF Update:

Tonight...High confidence. Low/mod for low clouds near Cape/Islands.

VFR conditions with light NE winds. We will need to watch for some spotty low clouds/fog patches towards the Cape/Islands developing toward 12Z. Lower confidence as the airmass is quite dry and it will be difficult to develop low clouds.

Tuesday...High confidence. Low/mod for low clouds on Cape/Islands.

VFR for most. Confidence lower in the potential for periods of BKN low clouds near the Cape and Islands. E-NE winds 6-15 kts with the strongest near the coast. NE winds gust to between 20 and 25 knots across the Cape and especially Nantucket during the daylight hours.

Tuesday Night...High confidence. Moderate for ceilings.

VFR for most. MVFR-IFR ceilings develop across Cape and Islands potentially reaching the east coast and BOS after midnight (lower confidence).

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday: VFR. Slight chance SHRA.

Wednesday Night: Mainly VFR, with local IFR possible. SHRA.

Thursday: MVFR/IFR conditions possible. Breezy. SHRA, slight chance TSRA.

Thursday Night: Mainly VFR, with areas MVFR possible. Windy with local gusts up to 30 kt. Chance SHRA.

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

Friday Night: Mainly VFR, with local MVFR possible. Breezy.

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 Tuesday night...High confidence.

High pressure centered over the Canadian Maritimes with distant low pressure well southeast of the Benchmark will result in persistent NE winds tonight through Tue night. This long fetch will generate 3 to 6 foot seas across the outer-waters...so current small craft headlines will persist. Some marginal NE 20-25 knot wind gusts possible for Nantucket sound again on Tue...so another small craft headline may need to be posted for Tue once the current once expires this evening for that region.

Outlook /Wednesday through Saturday/...

Wednesday: Winds less than 25 kt. Areas of rough seas. Chance of rain showers.

Wednesday Night: Winds less than 25 kt. Local rough seas. Chance of rain showers.

Thursday: Winds less than 25 kt. Areas of rough seas. Rain showers, slight chance of thunderstorms.

Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers.

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

Friday Night: Winds less than 25 kt. Seas up to 5 ft.

Saturday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ232. Small Craft Advisory from 2 AM Tuesday to 8 AM EDT Thursday for ANZ250. Small Craft Advisory until 8 AM EDT Thursday for ANZ254>256.