Lexington Weather

Lexington, Massachusetts, USA

36°F
1/27/2020 7:44am 
  • Lexington Conditions: Overcast
  • Temperature: 36.3°F / 2.4°CWarmer 0.2°F than last hour.
  • Dew Point: 31.3°FDecreased 0.2°Fsince last hour.
  • Relative Humidity: 82%Decreased 1.0% since last hour.
  • Wind: Wind from SW SW 2 mph, 10-min avg: 2 mph, gust: 8 mph
  • Barometer: 29.57 in Steady
  • Visibility: 10 miles
  • Rain Today: 0.00 in
  •   

Area Forecast Discussion
for Boston, MA

        
000
FXUS61 KBOX 271138
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
638 AM EST Mon Jan 27 2020

.SYNOPSIS...
Varying amounts of clouds much of the week ahead along with mainly 
dry weather. Cooler weather overspreads the area Monday and Tuesday 
with colder air to follow Tuesday night into Thursday. Temperatures 
begin to moderate Friday.  There is the potential for a storm to 
impact the region sometime this weekend, though it remains far from 
a certainty at this point.

&&

.NEAR TERM /THROUGH TONIGHT/...

645 am update...

Main update this morning to expand coverage of light flurries
across eastern MA. Lots of low level dry air (dewpoint
depressions of 10-15 degrees) and any flakes that make it to the
ground shouldn't accumulate given warmer surface temps. 

Previous Discussion...

Northern stream short wave approaches the region from the west today 
providing cyclonic flow and lots of clouds especially inland and the 
high terrain with less clouds across the coastal plain. Not much 
moisture from this feature so any snow showers/flurries should be 
confined to the upslope regions of the Berkshires and possibly the 
Worcester Hills. Although with lots of dry air below cloud bases any 
activity should be fairly localized. Otherwise the remainder of the 
region should remain dry. Not as mild as Sunday with 850 mb temps 
down to about -6C today. Although well mixed boundary layer and some 
downslope WNW wind component should support highs of 40-45, except 
upper 30s high terrain which is still 5-10 degs above normal. A 
modest WNW wind will make it feel a bit cooler.

&&

.SHORT TERM /TUESDAY/...
235 AM Update ...

Tonight ...

Dry weather continues behind departing short wave along with 
decreasing clouds after sunset. Weak cold air advection behind the 
trough with 925 mb temps cooling from about 
-2C at 00z to -4C by 12z Tue. Brisk NW winds at sunset will diminish 
as boundary layer likely decouples except in the urban areas, high 
terrain and Cape Cod/Islands should be enough pres gradient for at 
least some wind. Cooler but lows still a few degs above normal with 
low temps in the 20s, except 30-35 in the urban areas and Cape 
Cod/Islands. 

Tuesday ...

Dry weather likely prevails with next potent northern short wave not 
approaching the region until Tue night. The only exception to dry 
weather may be across the outer Cape including Nantucket and Cape 
Ann if winds have enough northerly component to generate some ocean 
effect snow (OES) showers. All Hi Res guidance hints at this OES 
potential. 925 mb temps cool a bit more to about -3C, supporting 
highs from the upper 30s to lower 40s, mid 30s high terrain. Still a 
few degs above normal. Regarding cloud cover, breaks of sunshine in 
the morning likely give way to diurnal clouds with cooling temps 
aloft and cyclonic flow. Clouds most abundant over Cape Cod and 
Nantucket with winds becoming northerly and cold advection across 
the relatively warm ocean waters.

&&

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

* Generally dry with near-slightly above normal temps Tue through Fri

* Potential storm next weekend, but uncertainty is high

Details...

Tuesday night through Friday...

Another remarkably quiet week upcoming which continues clear through 
at least Friday under an incoming surface high and mid level 
ridging. Late Tuesday night into Wednesday will be our only chance 
at some precip, over Cape Cod and the islands. We'll likely be 
dealing with some ocean enhanced clouds and snow showers during the 
evening and overnight hours as a weak shortwave rotates through and 
we have good moisture in the low levels. By Wednesday night winds 
before more northerly, but the moisture is gone. That leaves us with 
sunny skies Wednesday/Thursday and partly sunny skies on Friday as 
SW flow on the backside of the ridge brings in more moisture. It 
also brings in milder air, so after our coldest day on Thursday 
(highs in the low 30s) Friday will be quite a bit warmer, in the low 
40s. 

Next Weekend...

There remains a high degree of uncertainty with next weekend's 
potential storm system. The key word is "potential." Possibilities 
range from a rainy inside runner to a significant snow storm to the 
chance that we see nothing more than a weak frontal wave that stays 
out to sea. A lot rides on whether a couple of northern and 
southern stream disturbances can phase and bring the right combo
of moisture and cold air together. At the moment all options 
are on the table and ensemble spread continues to indicate the 
possibility of a track favorable for southern New England 
precip. Another complicating factor for those craving some snow 
will be the warmer than average antecedent airmass; highs on 
Friday and Saturday will be in the low 40s so ptype with any 
system is uncertain. Stay tuned!

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...

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

12z update...

Short Term... High confidence.

Today...

Cigs BKN-OVC040-050 today. Mainly dry weather with any light 
snow showers/flurries confined to western MA. SW winds this 
morning becoming west this afternoon.

Tonight...

Decreasing clouds with VFR. Modest WNW winds.

Tuesday...

VFR to start but then MVFR cigs develop over high terrain and
also along eastern MA coast from Cape Ann to Cape Cod to
Nantucket along with isolated -SHSN. 

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Tuesday night through Thursday/ ...

Tuesday Night through Wednesday: VFR. 

Wednesday Night through Thursday: VFR. Breezy. 

Thursday Night through Friday: VFR.

&&

.MARINE...
Short Term /through Tuesday/...High confidence. 

Today ... SW winds 15-20 kt with gusts up to 25 kt then becoming 
west at the same speeds this afternoon. Dry weather and good vsby. 

Tonight ... light NW winds along with dry weather and good vsby. 

Tuesday ... NNW winds 10-15 kt. Scattered rain/snow showers eastern 
waters from Nantucket to Cape Cod to Cape Ann. Mainly dry
elsewhere. 

Outlook /Tuesday Night through Friday/...

Tuesday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Slight chance of snow showers. Areas of visibility 1 to
3 nm.

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

Wednesday Night: Winds less than 25 kt. Local rough seas. 

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

Thursday Night: Winds less than 25 kt. Seas locally approaching
5 ft. 

Friday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 10 AM this morning to 5 PM EST this 
     afternoon for ANZ232>234.
     Small Craft Advisory until 7 PM EST this evening for ANZ235-
     237-250-254>256.
     Small Craft Advisory until 5 PM EST this afternoon for ANZ251.

&&

$$
SYNOPSIS...Nocera/BW
NEAR TERM...Nocera/BW
SHORT TERM...Nocera
LONG TERM...BW
AVIATION...Nocera/BW
MARINE...Nocera/BW
      

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