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Area Forecast Discussion (AFD)

Issued by Boston / Norton, MA (BOX)

                            
000
FXUS61 KBOX 151939
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
339 PM EDT Sun Sep 15 2019

.SYNOPSIS...

High pressure will bring an extended period of dry weather into
next weekend, other than perhaps a brief spot shower or two on 
Monday. The high will initially be accompanied by unseasonably 
cool weather Tuesday into Thursday morning. A gradual warmup is 
expected with temperatures possibly rebounding into the 80s 
Friday through Sunday.

&&

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

West to northwest flow aloft will allow for mid and high level
cloudiness to increase tonight ahead of a weak wave of low
pressure. Nonetheless, expect dry weather to continue tonight
with low temperatures mainly in the 50s by daybreak Monday. 
Winds will be rather light too, so a pleasant night of weather 
is on tap for the region.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Monday...

A weak wave of low pressure across the southern Great Lakes
early Mon morning will slide southeastward through the day. 
This will take the better forcing/moisture to the southwest of 
our region. So while we probably will see a period of some
cloudiness, at least across our CT/RI and SE MA expect little if
any rain other than a few spot showers. Greatest risk will be 
across northern CT and near the south coast, but regardless dry
weather should dominate in this region too.

High temperatures on Monday will probably still reach the lower
to middle 70s in many locales given at least some partial 
sunshine.

Monday night...

High pressure in Quebec will force a cold front south of the
region Monday evening. While dry weather should continue Monday
night it will turn cooler on northerly winds. Low temperatures 
by daybreak Tuesday should mainly be in the middle 40s to the 
lower 50s.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...

Highlights...

* High pressure brings dry weather Tuesday through Sunday
* Cooler than normal Tue-Thur, warming Friday into the weekend

Details...

Precipitation...

An very dry forecast in the extended, painting the picture for a
very pleasant week/weekend in southern New England. Building 
surface high pressure with a persistent mid level ridge set up 
to our immediate west will keep southern New England under a dry
N/NW flow through at least Saturday. No significant weather to 
speak of. 

Temperatures...

A very Fall-like feel will arrive beginning Tuesday and lingering 
through at least Thursday. This as N/NE flow sets up around the 
sfc-H85 high ushering in cold Canadian air. H85 temps drop to 
the 2-5C range by mid week, with the coldest period likely being
Wed and Thursday morning. Highs Tuesday and Wednesday won't 
break out of the 60s, compared to average highs of 70-75. Steady
warming is expected thereafter. Thursday some 70s return, then 
we get well into the 70s Friday and back into the 80s for the 
weekend. Yes, the return of summer-like temperatures is possible
this weekend into early next week as the ridge moves overhead. 
Before that, though, we'll also be dealing with chilly low 
temperatures. Given the dry, calm, clear nights we'll get some 
decent radiational cooling, with lows bottoming out Thursday 
morning in the 40s before rebounding to the 50s by the weekend. 

Tropical Storm Humberto...

We continue to expect little to no impact from Tropical Storm 
Humberto as model guidance shows the surface high helping to 
deflect it out to sea well to our south and east. As mentioned 
previously, the only real impact we may see would be increased 
swells for the MA/RI waters, bringing rough surf and strong rip 
currents around Friday/Saturday. 

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...

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

Short Term /through Monday Night/...High confidence.

Tonight...VFR conditions continue despite an increase in some
mid and high level cloudiness.  Rather light winds.

Monday...VFR conditions dominate despite some mid level
cloudiness. Low risk of brief MVFR conditions south of the MA 
Turnpike and perhaps a spot shower or two. Rather light winds.

Monday night...VFR.  North winds of 5 to 10 knots.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF. 

Outlook /Tuesday through Friday/...High confidence.

Tuesday: VFR. Breezy. 

Tuesday Night: VFR. 

Wednesday: VFR. Breezy. 

Wednesday Night through Friday: VFR. 

&&

.MARINE...
Forecaster Confidence Levels...

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

Short Term /through Monday Night/...High confidence.

Tonight and Monday...Weak pressure gradient will keep winds and
seas well below small craft advisory thresholds.

Monday night...A cold front will cross the waters Monday
evening. Decent mixing in the cool air advection pattern should
yield a period of northerly lower 20 knot wind gusts and 2 to 4
foot seas. We can not rule out brief SCA conditions, but threat
is too marginal to hoist any headlines at this point.

Outlook /Tuesday through Friday/...Moderate confidence.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

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