Updated: 110 AM EST Thu Nov 21 2024
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A slow-moving low pressure area spreads welcomed steady light to moderate rain today, before tapering to intermittent rain showers tonight into early Friday. Rain could mix with slushy wet snow above 1500 feet elevation tonight but no wintry impacts are expected. Another round of steady light rain moves through eastern New England Friday afternoon and evening. Low pressure slowly progresses into the Maritimes for the weekend, with gusty northwest winds and more clouds than sun are anticipated. Dry weather then returns for Monday before an unsettled weather pattern develops again for the middle of next week.
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UNTIL 6 AM THIS MORNING
730 PM update...
Dry, tranquil weather continues this evening and for much of the overnight period. Clouds approaching from the west via WAA aloft, along with low clouds approaching from the east given onshore flow. However, much of the night will be dry. Leading edge of the rain shield is across central PA into western NY. Current radar and model trends still have the rain arriving into western-central CT/MA between 09z-12z, then overspreading RI and eastern MA between 12z-15z, possibly closer to noon for Cape Cod and Nantucket. Some of the heavy rain will impact the AM commute across western-central CT/MA, including Hartford and Springfield.
Not as chilly tonight as previous nights given increasing dew pts and cloud cover.
Lows 35-40, except 40-45 in the urban areas and along the coast given onshore flow. Previous forecast captures these trends, therefore no major changes with this update..
6 AM THIS MORNING THROUGH 6 PM FRIDAY
Thursday through Thursday night will be the main focus of the forecast, especially for those with interest in seeing diminished fire activity. The pattern makes a switch as the upper low over the Great Lakes and its surface reflection sink into the Mid- Atlantic. This spawns a secondary low pressure center along the frontal boundary just off the east coast which subsequently deepens as it lifts directly over southern New England on Thursday and retrogrades backs toward eastern New York Thursday night. A deep plume of moisture will accompany this system with PWATs on the order of one inch. Strong dynamic lift (35-45kt LLJ and 500 mb PVA) with the aforementioned moisture will lead to a blossoming precipitation shield that overspreads SNE from 2AM (west) to 10AM (east) and continues all of Thursday and the first half of Thursday night before a dry slot works its way north into the region.
Thereafter showers become more scattered in nature with the low continuing to be just to our west.
Rainfall amounts continue to look solid for a meaningful rainfall, with 1 to 1.75 inches possible; the heaviest amounts will be in the high elevations of western MA where easterly upslope flow assists. As for snow potential, there will be enough cold air aloft and moving in on the back side of the system to bring some wet flakes to the upper reaches of the Berkshires, mainly above 1500 ft. However, not expecting efficient accumulation; a slushy inch or two are most likely.
As for the winds on Thursday, it will be a blustery and cool day with that LLJ overhead, easterly winds gusting 20 to 30 mph, especially along the coasts; it will be a windy and rough day on the our waters as well..
FRIDAY NIGHT THROUGH WEDNESDAY
Highlights:
* Cloudy, damp and overcast Fri night, with steady rains breaking out in the coastal plain.
* Gusty NW winds this weekend, with more clouds on Sat along with off-and-on showers. Seasonable temps but the winds will make it feel cooler.
* Dry for Monday, but turning more unsettled into midweek.
Details:
Friday Night:
Cloudy, damp and unsettled conditions for Southern New England continue into Fri night with vertically-stacked circulation continuing to meander around western New England/southern NY vicinity. However there still looks to be a round of steadier light rains which develop/rotate NNW from the southern waters into eastern MA, the Cape and the Islands. Looking at GEFS/EPS/GEPS ensemble members, there is a significant enough majority of members which keep this secondary burst of steadier rains into the MA/RI coastal plain with lighter intermittent precip over western MA/CT.
However QPF amts are still pretty variable; while QPF amts are more commonly in the quarter to half inch range in the coastal plain thru Fri night, there are a minority of members up to 3/4ths an inch. By early Sat AM, this band of steadier rains should shift NNE into coastal ME/NH as the broader upper level low begins to pull offshore.
The Weekend:
Ensembles continue to trend toward a slower NE departure of the upper-level low and its cold pocket of air aloft for the weekend. Thus a trend toward cloudier conditions for Sat with off-and-on light showers, with better chances in eastern and northern MA, Cape and Islands. Less cloud cover in general for Sunday, with more in/around the terrain but with drier conditions.
Highs on Sat in the 40s to around 50, and with a pretty strong NWly gradient flow and cloud cover, lows may only fall into the upper 30s to low 40s. With less cloud cover, highs Sun in the 40s to lower 50s with lows in the 30s Sun night.
The cooler temperatures aloft and a robust NW gradient flow will also contribute to rather blustery to gusty NW winds through the weekend. Model soundings also continue to show mixing up to about 900 mb on Sat, and slightly higher around 850 mb for Sun with a little less cloud cover and slightly warmer temps. For Sat, NW gusts could reach into the 25 to 30 mph range during the daytime hrs. Strongest 925 mb jet of 35-40 kt moves thru Sat night into early on Sun, and we should still realize gusts around 20-25 mph into the evening for most areas, but could punch up to around 35-45 mph over the Berkshires, hills in Worcester County as well as the Cape and Islands.
Still see gusts in the 25 to 35 mph range for Sunday thru the early afternoon, then beginning to subside late in the day as gradient starts to relax and low level jet core shifts offshore. Potential for gale headlines for the waters, although over land, confidence in gusts reaching Advisory levels is lower but could be possible if we mix deeper. Will reassess gusts as we get into the mesoscale model forecast horizon.
Monday:
Still looking at pretty tranquil weather conditions for Mon with weak shortwave ridging aloft and modest SW winds allowing for highs in the low to mid 50s.
Monday Night through Wednesday Night:
A more active weather pattern is indicated by most of the ensembles into the early to middle part of next week, as slow-evolving trough energy circulating over the West Coast/Pac NW begins to eject eastward off the Rockies.
At least one frontal system moves in during this period, around the Mon night/Tue timefame, although there are still significant differences in strength with this potential system. Forecast confidence is still on the low side in this period and stayed fairly close to NBM forecasts for this period until those differences shake out..
Forecast Confidence Levels:
Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.
06z TAF Update:
Through 12z Thursday: High confidence in trends, moderate on timing.
MVFR stratus initially (IFR at ORH) with dry weather for at least another couple hrs. Steady light to moderate RA with vsbys 3-6 SM now over the lower Hudson Valley then breaks out into BAF/BDL around 08-10z, and into central MA/RI by ~10-12z. Better chance for steadier rains eastern airports just after 12z. Ceilings may trend closer to MVFR/borderline IFR range as steady rain breaks out. Light E winds to start but will increase to around 7-10 kt thru 12z Thurs.
Today: Moderate confidence.
3-5 SM RA spreads across all airports early this AM, which continues into early tonight. Rain will become increasingly wind-driven as E winds increase to around 10-15 kt with gusts 20-25 kt near the E MA coast.
MVFR/IFR ceilings continue, though ceilings likely to dance between 800-1500 ft most of the day. Took a pessimistic approach with the TAFs indicating IFR, however there could be MVFR intervals in between but difficult to pinpoint a timing.
Tonight: Moderate confidence.
Widespread 3-6 SM steady RA early tonight trends to more of an intermittent -SHRA or even -DZ between 00-06z, earliest south and later north. Steadier light rain likely to continue at BAF/BDL. Improvement in ceilings toward OVC MVFR interior, and become BKN/OVC VFR over eastern/southeast New England. Winds start E around 10-15 kt with gusts 20-25 kt, though will become SE/S around 10-14 kt with lesser gusts to around 20 kt.
Friday: Moderate confidence.
MVFR ceilings with periods of -RA interior CT/MA, BKN/OVC VFR ceilings with initially dry wx eastern airports. Later in the afternoon a band of rain moves northward from the ocean and spreads across eastern MA/RI, exact timing uncertain but likely not sooner than 18z. SE to S winds around 7-14 kt with gusts up to 20 kt.
KBOS Terminal...Moderate confidence in TAF. MVFR cigs initially, trending IFR/MVFR with 3-6 SM RA developing around ~12-13z. Cigs could flip between IFR-MVFR levels frequently today. Wind-driven rain on ENE/E winds around 15 kt today with gusts 20-25 kt. RA tapers off around 03z to a intermittent light -SHRA, with winds becoming SE around 10-13 kt.
KBDL Terminal...Moderate confidence in TAF. MVFR cigs initially, trending IFR-MVFR w/ 3-6 SM RA developing around ~08-10z. Steady light to moderate RA continues thru about 02z before lightening up. E winds around 10 kt today, becoming SE tonight.
Outlook /Friday Night through Monday/...
Friday Night: Mainly MVFR, with local IFR possible. RA likely.
Saturday: Mainly VFR, with local IFR possible. Windy with local gusts up to 30 kt. Chance RA.
Saturday Night: Mainly VFR, with local MVFR possible. Windy with gusts up to 35 kt. Slight chance RA.
Sunday: VFR. Windy with gusts up to 35 kt.
Sunday Night: VFR. Breezy.
Monday: VFR.
Forecaster Confidence Levels:
Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent.
This evening through Thursday night...
Calm/tranquil conditions this evening with weak high pressure supporting light winds over the coastal waters. Conditions begin to deteriorate overnight as an area of low-pressure moves over the south coastal waters. Winds strengthen out of the east to speeds of 15 to 25 knots with gusts up to 30 knots by tomorrow. Moderate easterly winds continue through the day Thursday with seas building to 6 to 8 feet. A few gale force gusts up to 35 knots will be possible, especially over the southern marine zones through Thursday afternoon. However, confidence in a prolonged period of gales is not high enough to warrant gale headlines. Nonetheless, solid SCY conditions will be present over the coastal waters likely through much of the day Friday and beyond.
Outlook /Friday Night through Monday/...
Friday Night: Winds less than 25 kt. Seas up to 5 ft. Rain.
Saturday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Rain likely.
Saturday Night: Moderate risk for gale force winds with gusts up to 35 kt. Rough seas up to 11 ft. Chance of rain.
Sunday: Strong winds with gusts up to 35 kt. Rough seas up to 10 ft.
Sunday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas.
Monday: Winds less than 25 kt. Areas of seas approaching 5 ft.