Lexington Weather

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 010555
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
155 AM EDT Wed Apr 1 2020

.SYNOPSIS...
Closed upper low pressure lingers over New England through 
midweek, but should see mainly dry conditions. An ocean storm 
will pass well south of the region late this week, bringing 
gusty and cool northeast winds especially along east coastal 
areas. An area of rain will move onshore across the region
Wednesday night into Friday morning, with wet snow possible 
especially across the high terrain. High pressure will bring 
dry but continued cool conditions Saturday. Another weak, fast 
moving system will bring unsettled weather on Sunday, then dry 
conditions return early next week.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
150 AM update...

Strato-cu has filled in across western MA/CT with lower clouds
across Cape/Islands and mainly clear in between. Expect lower
clouds to gradually fill in across SE MA overnight as low level
moisture backs in across SE New Eng. Strato-cu breaks up out 
west but high clouds will be moving in overnight.  

Previous discussion...

Clear skies across much of SNE, but areas of low clouds 
rotating south across waters north and east of Cape Cod and 
impacting the outer Cape and ACK. Low level RH fields indicate 
this moisture gradually moving west and HREF suggesting low 
clouds expanding across eastern MA overnight with a low risk 
for spotty light rain developing. Meanwhile, some strato-cu 
expected to fill in across western New Eng per 850 mb RH. Lows
will drop into the upper 20s to lower 30s before leveling off.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
Tomorrow will be watching mid level low emerging out of the TN  
Valley this afternoon as it tracks ENE off the Mid Atlc coast
Wed morning. Dry weather prevails across our region but clouds
may dominate the day across eastern MA given NE onshore flow and 
perhaps some light rain late in the day over Cape Cod and
Islands. However farther inland across RI/CT and western-central 
MA expecting dry weather to prevail with at least partial
sunshine. Despite the partial sunshine inland temps will remain 
chilly given same airmass in place. Expecting highs in the mid
to upper 40s inland and upper 30s to lower 40s across eastern
MA. Thus another cooler than normal day and gusty NE winds up to 
25-30 mph across Cape Cod and Islands will add to the chilly 
conditions. 

Wednesday night ...

Low tracking well southeast of New England and deepens to about
980 mb by 12z Thu as it enters southeast Georges Bank. While
most of our area will remain dry given this distant storm track, 
the mid level circulation is very large and wraps warm air aloft
(TROWAL) back into New England. This will support a risk of rain 
entering eastern MA. Per model soundings column is cold enough
to support some light snow per wet bulb temps but precip may not 
be heavy enough for wet bulb temps to be realized. Thus,
expecting mainly light rain now but will have to watch if
heavier precip rotates westward.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Highlights... 

* Near to below normal temperatures through Saturday night, the
  near to above normal temperatures into early next week

* Periods of showers developing sometime late Wednesday night
  into Friday

* Dry Saturday, then spotty showers with another weak 
  disturbance Sunday

* Mainly dry conditions Saturday through Tuesday, expect for
  some scattered showers possible with a cold front passage 
  Sunday into Sunday night

Details....

Mid level flow not expected to evolve too much through the end
of this week. Still thinking southern New England will be under
the influence of a persistent cutoff meandering between the
Great Lakes and the North Atlantic. This pocket of colder air
aloft will maintain some instability where showers will result
at times. This cutoff should finally move far enough away from
our region towards Saturday. Expecting the weather pattern to be
more progressive as we head into early next week.

At the surface, expecting an offshore low pressure to
retrograde back to the west Thursday night into Friday. While
this low should remain over the North Atlantic, it should get
close enough to produce a period of showers, especially across
eastern MA. Depending upon the exact timing, which is not yet
known, there is a risk for some wet snowflakes across the 
higher terrain of central and western MA Thursday night.

With a high pressure farther to the north, the pressure gradient
increases. Could be quite gusty towards the coasts during this
time, too. 

As this low pressure moves farther away Friday into Saturday,
looking at a drying trend. Winds will diminish Friday night, 
but will remain onshore so could see a few isolated showers 
lingering across Cape Cod and the islands. High pressure then 
passes by Saturday, with another cold front sweeping across our
region Sunday. We should return to the influence of a high
pressure early next week.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...

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

Through 12z...
MVFR cigs Cape/Islands spreading inland across SE MA, otherwise
mainly VFR. 

Today...Moderate confidence due to some uncertainty with how 
far inland MVFR cigs will track.

Expect MVFR cigs developing across much of eastern MA/RI this 
morning with pockets of IFR this afternoon outer Cape/Islands. 
Mainly VFR to the west. Low risk for some light rain developing 
late in the day Cape/Islands. N wind gusts 25-30 kt developing 
in the afternoon over Cape/Islands.

Tonight....Moderate confidence. 
MVFR cigs eastern MA/RI with localized IFR outer Cape/ACK. 
Mainly VFR to the west. Occasional light rain developing over 
the Cape/Islands and possibly spreading across eastern MA 
overnight. N wind gusts to 35 kt over ACK and outer Cape with 25
kt gusts developing along the coast. 

Thursday...Moderate confidence. 
MVFR with occasional rain developing eastern MA/RI gradually 
spreading west and possibly reaching CT valley by late 
afternoon. Areas of IFR Cape/Islands. N wind gusts 35-40 kt 
outer Cape/ACK with 25 kt gusts elsewhere. 

KBOS Terminal...High confidence in trends, but lower confidence
on exact timing. MVFR cigs developing 12-14z.

KBDL Terminal...High confidence.

Outlook /Thursday Night through Sunday/... 

Thursday Night: Mainly MVFR, with areas IFR possible. Windy 
with gusts up to 35 kt. Chance SHRA, patchy FG.

Friday: MVFR/IFR conditions possible. Windy with gusts up to
35 kt. Slight chance SHRA.

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

Saturday: Mainly VFR, with areas MVFR possible. Breezy. 

Saturday Night: VFR. 

Sunday: Mainly VFR, with local MVFR possible. Chance SHRA.

&&

.MARINE...
Tonight...Modest NNE wind 10-15 kt with gusts up to 20 kt. Seas
5-8 ft across the outer waters given long NE fetch. Mainly dry 
weather and good vsby. 

Wednesday...Low pres emerges off the NC coast and moves ENE 
well south of New England. However NE winds increase to 20-25 kt
late in the day. Seas build as well along with some light 
spotty rain.

Wednesday night...Low pres intensifies as it tracks well 
southeast of 40N/70W then into southeast Georges Bank. NNE winds
increase 20-30 kt along with vsby reduced in rain.

Outlook /Thursday Night through Sunday/...

Thursday: Low risk for gale force winds with gusts up to 35 kt.
Rough seas up to 12 ft. Rain showers likely, patchy fog. Local
visibility 1 nm or less.

Thursday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 18 ft. Rain showers likely, patchy fog.
Local visibility 1 nm or less.

Friday: Strong winds with gusts up to 35 kt. Rough seas up to
19 ft. Chance of rain showers. 

Friday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 18 ft. Slight chance of
rain showers. 

Saturday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Rough seas up to 16 ft. 

Saturday Night: Winds less than 25 kt. Rough seas up to 13 ft. 

Sunday: Winds less than 25 kt. Rough seas up to 10 ft. Slight
chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from noon today to 8 PM EDT Thursday for 
     ANZ231>235-237.
     Small Craft Advisory until 8 PM EDT Thursday for ANZ250-251-
     254>256.

&&

$$
SYNOPSIS...Belk/Nocera
NEAR TERM...KJC
SHORT TERM...Nocera
LONG TERM...Belk
AVIATION...Belk/KJC
MARINE...Belk/Nocera