Old Res Weather

Lexington, Massachusetts, USA

31°F

2/9/2023 12:14am

Lexington Conditions: Clear
Temperature: 31.3°F / -0.4°C
Dew Point: 24.6°F
Relative Humidity: 76%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 30.27 in Steady
Visibility: 10 miles
Rain Today: 0.00 in
UV Index: $VPuv None

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 090240
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
940 PM EST Wed Feb 8 2023

.SYNOPSIS...
High pressure builds into the region tonight. Low pressure then 
tracks northwest of our region Thursday and Thursday night bringing 
showers to southern New England. Mainly rain is expected with this 
system, with a low probability of a wintry mix Thursday afternoon 
across far NW MA. Unseasonably mild temperatures, close to the 
records for the day, follow on Friday. Cooler and more seasonable 
weather returns this weekend. Low pressure moving off the mid Atlc 
coast is expected to remain well south of New England, but the 
northern extent of the precipitation shield may make it into 
portions of the region late Sunday into early Monday.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...

930PM Update...

Clear conditions continue to dominate the region this evening,
supporting healthy radiational cooling; the temperature 
dropping 4 degrees here at the office in just the last hour.
Radiational cooling will continue for the next few hours but
will be capped earlier across our western zones as high clouds
move in from the SW. 

Otherwise, forecast remains on track, see previous updates for
more detail. 

640 PM update...

High pres builds into New Eng tonight with diminishing winds
becoming near calm. Clear skies will give way to increasing high
clouds overnight. A period of good radiational cooling during
the first half of the night will allow temps to fall quickly 
before leveling off later tonight. Expected lows will drop into
the mid/upper 20s, except lower 30s near the coast. Forecast on
track.

Previous discussion...

A building mid level ridge and increasing subsidence from an 
approaching surface high pressure center are allowing for 
increasingly clear skies over southern New England. While mid level 
moisture has held on longer than expected, clear skies finally 
arrived and should stick around until the early overnight hours. 
That's when an approaching warm front will move in, first in the 
upper levels, leading a deck of cirrus clouds to overspread from 
southwest to northeast. These clouds will thicken and lower through 
the night. So, while winds will come down tonight as the high moves 
overhead, this will be later in the night when cloudcover is 
thicker. So, have only tweaked low temperatures a bit lower to 
account for some radiational cooling. Expect lows in the upper 20s 
and low 30s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Thursday starts with mostly cloudy skies, quickly becoming overcast 
as the surface warm front lifts through. This is associated with a 
vertically stacked low which will move from the Great Lakes into 
Canada, well to our north and west over the next 24 hours. What this 
means for us is that any precipitation that falls will be in the 
form of rain, with temperatures on Thursday reaching well into the 
40s. As the system moves closer it generates a 45 to 55 kt low level 
jet overhead which, while it will help provide lift for rain 
showers, will struggle to mix down to the surface. BUFKIT soundings 
show a stout inversion around 920 mb which should keep the stronger 
winds aloft until cold advection kicks in on Friday. The best chance 
for rain showers, especially early on, is for northern MA in closest 
proximity to the better forcing. While scattered showers are 
possible for all of southern New England during the evening and 
early overnight hours, rain shuts off after midnight as a mid level 
dry slot moves overhead.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Highlights...

* Windy & unseasonably mild Fri. Near record high temps.

* Cooler and more seasonable this weekend. Some rain may make into 
  southern portions of SNE late Sun into early Mon, with a lower 
  risk of rain or snow/mixed precip further N.

* Above normal temps early next week

Friday...

Rather mild start to the day with temps well into the 40s to lower 
50s. Cold front will be moving off the coast in the morning with 
cooling low level temps. Afternoon 925 mb temps around 5C with good 
mixing and westerly flow supports highs well into the 50s in the 
coastal plain and lower CT valley, with perhaps temps near 60 in a 
few spots across SE MA. Some diurnal cloud cover expected, otherwise 
partly to mostly sunny skies. The mild temps will be accompanied by 
windy conditions as well mixed boundary layer supports 25-40 mph 
gusts. 

Northern stream trough approaches Fri night with backing flow which 
will allow clouds to increase but area of southern stream moisture 
expected to remain to the south, with just a low risk a few showers 
could clip the Islands. 

Saturday through Monday...

Northern stream trough sweeps through Sat morning followed by NW 
flow and drying column. Expect lots of sunshine and cooler temps in 
the upper 30s and lower 40s. Cold night Sat night as high pres 
builds into New Eng with good radiational cooling resulting in lows 
in the teens and 20s. Then a southern stream low will emerge off the 
mid Atlc coast Sun night passing well south of New Eng Monday. 
However, building ridge ahead of this system expected to allow 
moisture to lift further N and possibly get into SNE. Expect much of 
Sunday to be dry, but it is possible some rain may begin to move 
into south coastal areas by late Sun. There is still uncertainty 
with how far north precip shield will get but confidence is 
increasing in a period of rain getting to at least the south coast 
through Sun night. And there is enough ensemble support for a low to 
moderate risk of precip making it further N into SNE with the threat 
of some wet snow or mixed precip the further N it makes it across 
SNE. Gusty NE winds also a risk near the coast with a modest low 
level jet developing. 

It appears precip could linger into Mon, especially near the coast 
but trend will be for improving conditions later Mon as storm pulls 
away. 

Tuesday and Wednesday...

Above normal temps expected Tue/Wed but lower confidence on 
PoPs/timing as an active pattern persists with multiple shortwaves 
rotating through a somewhat amplified flow pattern. GEFS and ECENS 
suggest mostly dry Tue with greater risk of showers Wed.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Forecaster Confidence Levels:

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

00Z TAF Update...

Tonight... High Confidence.

VFR with light northwesterly winds, less than 10 kt, calm across
portions of interior southern of New England.

Thursday... High Confidence in trends, moderate confidence in 
exact timing. 

VFR to start the day. Increasing clouds ahead of our next
rainmaker after 15-18Z from west to east. MVFR and light rain 
showers develop during the afternoon hours. Periods of IFR at
our western terminals possible before 00Z Friday, especially in
heavier bands of rain. Calm winds become southerly by Thursday
afternoon, increasing to about 15kt. 

Thursday night...moderate confidence. 

IFR in SHRA becoming VFR by 12Z. SW winds 15 to 20 kt. 

KBOS Terminal...High Confidence in TAF.

VFR through the period. Mid level clouds scour out to clear
conditions by late morning. Winds becoming West/Northwest winds
10-15 knots today with 20+ knot gusts by afternoon. Winds
diminish tonight.

KBDL Terminal...High Confidence in TAF.

VFR through the period. Mid level clouds scour out to clear
conditions by late morning. Winds becoming West/Northwest winds
10-15 knots today with 20+ knot gusts by afternoon. Winds
diminish tonight.
 

Outlook /Friday through Monday/... 

Saturday: VFR. Windy with local gusts up to 30 kt. 

Saturday Night: VFR. 

Sunday: VFR. Breezy. Slight chance RA.

Sunday Night: VFR. Windy with areas of gusts up to 30 kt.
Chance RA, slight chance FZRA, slight chance SN.

Monday: Mainly VFR, with local MVFR possible. Windy with gusts
up to 35 kt. 

Monday Night: VFR. Breezy. 

Tuesday: 

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight...

High pressure builds over the coastal waters tonight with lighter 
winds and decreasing seas. Conditions will fall below small craft 
criteria across the outer waters overnight. 

Thursday... NW flow gradually shifts to the south and builds through 
the day Thursday. Winds remain below small craft thresholds. Seas 
gradually build to near 5 feet again. 

Thursday night...SW winds increasing to 15-20kt gusting 25 to 30 kt. 
Seas build to 5 to 7 ft for the outer waters. 

Outlook /Friday through Monday/... 

Saturday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft. 

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

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

Sunday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Chance of rain. 

Monday: Low risk for gale force winds with gusts up to 35 kt.
Rough seas up to 10 ft. Chance of rain. 

Monday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. 

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

&&

.CLIMATE...
Record Maximum Temps for Fri 2/10...

Boston60/1990
Hartford55/1909
Providence58/1909
Worcester55/1909

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 1 AM EST Thursday for ANZ250-254-
     255.

&&

$$
SYNOPSIS...KJC/BW
NEAR TERM...KJC/BW/KS
SHORT TERM...BW
LONG TERM...KJC
AVIATION...KJC/BW
MARINE...KJC/BW
CLIMATE...