Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 210309
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
1009 PM EST Mon Feb 20 2017

.SYNOPSIS...
High pressure builds over the Northeast USA tonight and moves
offshore by Wednesday. This brings us dry weather tonight and
Tuesday. A series of low pressure systems move through the
Great Lakes Wednesday through Saturday bringing an extended
period of unseasonably mild temperatures, with near record
warmth possible Thursday. A strong cold front will cross the
region Saturday, likely bringing some rain, followed by blustery
and more seasonable conditions Sunday and Monday.

&&

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

Clear skies across much of New England. Signs of cirrus moving
in across Ontario and Western NY. Could be some morning surprise
cirrus after sunrise, but otherwise dry weather. The clear skies
and light winds will allow radiational cooling with dew points
in the teens in northern and western zones and 20-25 in SE Mass.
Expect min temps in roughly this same range...some upper teens
may occur in the colder spots of SE MA such as Taunton and
Norwood Airports.

Made a few adjustments to temps and dew points per 9 pm
observations. Otherwise the forecast grids look fine.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Tuesday...

Fairly high deep amplitude ridge over the region in the morning and
afternoon provides deep layer subsidence and abundant sunshine.
However as ridge continues to slide east, mid and high clouds will
begin to invade from the western horizon during the afternoon.

Chilly start to the day but despite shallow blyr mixing and light
winds from 1027 mb high overhead, temps will climb into the 40s
regionwide. Coolest readings will be along the immediate coast as
winds become onshore in the afternoon off the chilly near shore
waters with SSTs in the upper 30s.

Tuesday night...

High pressure moves offshore with WAA pattern overspreading the
region. Increasing clouds will give way to the risk for some showers
with highest pops...chance across western section of MA/CT. Only
wrinkle here is that shallow cold air may linger long enough across
northwest MA for a low risk of freezing rain. Temps around freezing
across interior eastern MA are some concern however precip may dry
up before reaching this area. Overall risk is low given marginal
cold airmass (temps near freezing vs temps in the 20s) and precip
possibly drying up as it moves eastward.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Highlights...

* Mild conditions Wed with near record warmth possible Thu
* A backdoor front may bring cooler temps Fri but low confidence
* Mild with widespread showers likely sometime Sat/Sat night
* Blustery and cooler Sun/Mon

Overview...

Guidance in general agreement on amplifying trof moving into the
Rockies and Plains toward the end of the week with building
downstream ridge along the east coast. This will result in a
period of unseasonably mild temps into the weekend, but will
have to watch a northern stream shortwave which could allow a
backdoor front to cool things off around Friday. Models agree on
mid level low lifting across the Great Lakes Sat with inside
runner and strong cold fropa likely bringing a period of rain,
although timing and details are uncertain. More seasonable and
blustery conditions follow for Sun/Mon as broad trof develops
across the NE.

Details...

Wednesday into Thursday...

Pronounced warming trend as high pres sets up south of New Eng with
SW flow of mild air into SNE. There may be some clouds to contend
with Wed as weak shortwave moves through with low risk of a few
showers and isold fzra early in the morning interior N MA, but
expect partly sunny skies in the afternoon as mid level drying
develops from the north. Highs should reach into the 50s Wed with
upper 50s possible in the coastal plain if there is sufficient
sunshine.

On Thursday, continued SW flow will push 925 mb temps to near 12C
which supports highs well into the 60s away from the south coast
with partly sunny skies. Even GEFS mean 925 mb temps around 10C so
above average confidence of temps above 60 Thursday with potential
for some upper 60s with sufficient sunshine. Could see near record
highs at some of our climate sites. See climate section below.

Friday...

Low confidence temp forecast as a backdoor front will be nearby and
may slip south of the region. GFS and GGEM push front to the south
with cooler temps while ECMWF hold the front to the north with temps
in the 60s again. Expect more cloud cover Fri along with a risk of a
few showers as deeper moisture moves into the region, but forcing
for ascent is limited so most of the time should be dry.

Saturday...

Timing uncertain but widespread showers likely to move into the
region sometime Sat into Sat night depending on the timing of the
cold front. Pre-frontal southerly low level jet should result in
more unseasonably mild temps.

Sunday into Monday...

A return to more seasonable temps with blustery W/NW winds as the
low pres moves into the Maritimes.

&&

.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

Short Term /through Tuesday Night/...

Tonight...

VFR. Diminishing winds becoming light.

Tuesday...

More of the same, VFR with dry weather and light winds.

Tuesday night...

VFR to start then MVFR with chance of a few showers except
probably remaining dry over RI and southeast MA. Interior MA
will have to watch the potential for some -FZRA with temps near
freezing.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday...Moderate confidence. Leftover MVFR/IFR conditions
possible in the morning, then improving to VFR.

Thursday...Moderate confidence. Mainly VFR.

Friday...Low confidence. Potential for easterly flow and MVFR cigs
if backdoor front slips to the south. However, VFR with SW winds if
front remains to the north.

Saturday...Moderate confidence. Potential for widespread MVFR/IFR
conditions with rain overspreading the region.

&&

.MARINE...
Forecaster Confidence Levels...

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

Short Term /through Tuesday Night/...

Tonight...High confidence. Diminishing winds have dipped below
25 knots all areas, but lingering 5 foot seas either measured or
implied on the outer waters east of Massachusetts. We will
maintain the existing Small Craft Advisory in that area until
morning.

Tuesday...High confidence. High pressure overhead will result
in light winds and flat seas.

Tuesday night...High confidence with winds becoming south.
Chance of showers and patchy fog late may reduce vsby at times.

Outlook /Wednesday through Saturday/...

Wednesday into Thursday...High confidence. Mainly SW flow with
gusts to 20 kt. A few gusts to 25 kt possible Thu afternoon.

Friday...Low confidence. Winds will depend on location of a backdoor
front. Easterly flow if the front moves to the south, but continued
SW flow with gusts to 20-25 kt possible if front remains to the
north.

Saturday...Moderate confidence. Increasing southerly flow with SCA
gusts likely. Vsbys reduced in developing rain and fog.

&&

.CLIMATE...
Record Highs for Thu Feb 23

BOS...65/1990
BDL...68/1990
PVD...60/1990
ORH...61/1990

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 6 AM EST Tuesday for ANZ250-254-255.

&&

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


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