textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast. High confidence in near record high temperatures Tuesday.

KEY MESSAGES

- Area of fog quickly dissipate by mid-Tue morning. Otherwise... sunshine returns Tue with near record highs in the upper 60s to lower 70s away from the immediate coast.

- A more unsettled/active weather pattern Wed/Thu, with a round or two of precipitation. Back to cool temperatures later Thu into Friday.

- With dew points in the 30s and 40s, along with minor precip events, expecting a controlled/diurnal snowmelt over the coming week. Hence, only minor river flooding possible.

DISCUSSION

KEY MESSAGE 1...Areas of fog quickly dissipate by mid-Tue morning. Otherwise...sunshine returns Tue with near record highs in the upper 60s to lower 70s away from the immediate coast.

Areas of fog overnight into Tue morning, especially near the south coast. The fog will quickly burn off after sunrise given a lot of dry air just above the boundary layer.

Lots of sunshine again tomorrow/Tue and even warmer temps aloft, from +12C/+13C today to +14/+15C Tue will yield another spring-like day, with highs in the upper 60s to lower 70s. Given this, we followed the warmer NBM 95 percentile for MaxT tomorrow. These temps will come close to record highs for the day (see climate section for specifics). Of course it will be noticeably cooler on the immediate south coast, Cape and Islands given S-SW winds streaming across the cool near shore waters.

KEY MESSAGE 2...Trending more unsettled Wed/Thu with a round or two of precipitation. Back to cool temperatures late Thu into Friday.

Backdoor front slips into northeast MA late Tue night/early Wed and then slowly lifts north as a warm front later Wed. This will yield lots of clouds Wed along with a chance of showers, but by no means a washout. Not as warm Wed given cloud cover and onshore flow, but still mild with highs in the 50s, 60-65 inland. Deepening parent low tracks thru the St Lawrence River Valley Wed night, with its attending cold front entering SNE Thu. Strong jet dynamics coupled with good moisture advection will yield widespread showers Wed night into Thu. Models showing lots of spread regarding potential anafrontal precip, with some of the guidance supporting rain changing to snow and/or sleet before ending across the high terrain. Friday the post frontal airmass overhead means cooler temperatures, highs 40-45, which is on target for this time of year. Another northern stream low passes to our north late Fri/Fri night, which may bring some scattered rain/high elevation snow showers. Dry weather is likely Sat behind this system and possibly lingering into much of Sunday, before the next system impacts SNE Sun night into Monday.

KEY MESSAGE 3...Expecting controlled/diurnal snowmelt over the coming week. Thus, only minor river flooding possible.

Given dew pts are only expected to rise into the 30s and 40s, along with minor precip events, we are expected a controlled/diurnal snowmelt. This will contribute back to the watershed leading to rises, but for the reasons mentioned above, only expecting minor flood stages to be observed as a worse case scenario. Guidance continues to indicate the most likely spots to see flooding are along the Connecticut River by next weekend with addition of S. RI rivers by early next week.

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 in TAF/trends but moderate on exact timing.

VFR away from the immediate south coast, with SW winds decreasing to around 5 kt. Areas low-level wind shear possible through 08z, although 2000' winds look weaker and left out LLWS mention from TAFs. Meanwhile anticipating IFR-VLIFR stratus and fog to develop along the immediate south coast, Cape and Islands now that the sun has set. Satellite shows marine fog and stratus expanding in areal coverage over the far southern waters and would expect fog/stratus to develop between 01-03z and then persist though 12z.

Tuesday: High confidence, though moderate along the south coast.

Areas IFR-VLIFR in fog/stratus along the south coast/Cape and Islands initially should trend to a IFR-MVFR stratus early Tue AM; categories are in some question here as sub-VFR stratus could lurk around for quite a while as moisture is trapped underneath very strong thermal inversion. VFR elsewhere with SW winds around 5-10 kt; winds too strong for seabreeze to develop at BOS.

Tuesday Night: Moderate confidence.

IFR-LIFR fog/stratus should expand northward from the waters into at least the south coast/Cape and Islands. Conditions should be VFR for most of the time elsewhere; however a backdoor cold front could southward as soon as 08z Wed and bring at least MVFR- IFR ceilings and increasing NE winds to BED-BOS-ORH- PVD. Timing of this backdoor front is still unclear.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Tuesday Night through Saturday/...

Wednesday: Mainly VFR, with local MVFR possible. Breezy. Chance RA.

Wednesday Night: Mainly VFR, with local IFR possible. Breezy. Chance RA.

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

Thursday Night through Friday: VFR. Breezy.

Friday Night: Mainly VFR, with local MVFR possible. Breezy. Chance RA, chance SN.

Saturday: Breezy.

MARINE

Forecaster Confidence Levels...

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

Today through Tuesday night...High confidence.

A weak pressure gradient will keep winds and seas below small craft advisory thresholds through Tue night. Areas of fog...some of which will be dense at times will impact our southern waters during the overnight and early morning hours. This will result in poor vsbys for mariners at times, but improving by mid to late morning.

Outlook /Tuesday Night through Saturday/...

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

Wednesday Night: Strong winds with areas of gusts up to 30 kt. Areas of rough seas. Chance of rain.

Thursday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 10 ft. Chance of rain.

Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Chance of rain, slight chance of snow.

Friday: Winds less than 25 kt. Areas of seas approaching 5 ft.

Friday Night: Strong winds with gusts up to 30 kt. Seas up to 5 ft. Chance of rain.

Saturday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas.

CLIMATE

Record highs for Tuesday, March 10th...

BOS...71...1878 PVD...72...2016 BDL...72...2016 ORH...67...2020

Average high for 3/10 is 40-45.

BOX WATCHES/WARNINGS/ADVISORIES

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