Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 252021

Area Forecast Discussion
National Weather Service Taunton MA
321 PM EST Sat Feb 25 2017

A strong cold front will cross the region tonight, bringing
showers and a low chance for thunderstorms as this front passes.
Blustery conditions with more seasonable temperatures expected
for Sunday and above average on Monday. A couple of weather
systems will bring periods of wet weather Tuesday into Thursday.
Colder air looks to return late next week.


Fine line of convection along the cold front moving into
eastern NY. Sct to numerous t-storms along this line where
MUCAPES 250-500 J/kg but MUCAPES 1000-1500 J/kg further south
across SE PA where greater severe wx threat exists. Hi-res
guidance indicates this line will move into western MA and
northern CT 00-02z. Strong mid level omega holds together into
W MA along with 40-50 kt LLJ so expect the line to maintain
itself as it moves into W MA early this evening but the line of
convection will begin to outrun better instability to the west
so some weakening is expected. Still expect brief heavy
downpours and gusty winds in western MA and N CT with low risk
of an isold damaging wind gust if convection can mix down
stronger winds aloft. Will have to monitor radar closely as deep
layer shear and 0-1km helicity values are quite robust and
damaging wind or even a brief tornado is favorable in this
environment if instability is greater than forecast.

As the line moves east across central and eastern New Eng
02-06z it will diminish and weaken as mid level omega weakens
rapidly and becomes fragmented. So just a few showers expected
by the time it gets to eastern MA. The rain may end as a brief
period of snow showers in the Berkshires as deeper colder air
rushes in behind the front, but moisture will be exiting as the
cold air moves in. Low risk of a coating to less than an inch in
the Berkshires.

Gusty W/NW winds develop behind the cold front which moves
through SNE 01-06z from west to east. Gusts to 30-40 mph
possible, strongest over higher terrain. Min temps by Sun
morning will range from 35 to 40 degrees, except upper 20s to
lower 30s over the higher terrain in central and western MA


Mid level shortwave moves east of New Eng. Expect partly to
mosunny skies with sct-bkn strato-cu developing in cold
advection pattern. Gusty W/NW winds expected with soundings
supporting gusts to 35 mph with chance of a few gusts over 40
mph across the higher terrain where low prob a wind advisory
may be needed.

Much colder airmass Sun as 850 mb temps drop to -8 to -10C.
However, temps will likely overachieve a bit as soundings
indicate mixing above 850 mb with good downsloping. Expect
maxes ranging from the upper 30s higher elevations to the mid
40s in the coastal plain with a few upper 40s possible.

Sunday night...
Surface high moves off mid Atlc coast with ridge axis moving
east of New Eng. Winds will diminish and shift to SW overnight.
Column is dry except for some increase in mid/high level
moisture. Expect mostly clear to partly cloudy skies with mins
ranging through the 20s.



* Above average temperatures for next week
* Widespread showers possible Wednesday/Thursday
* More seasonable conditions return on Friday

Pattern Overview...

The 00z models and their ensembles have been in generally good
agreement through the period with the GFS just a bit displaced.
Therefor used a blend of the ensembles for the bulk of the
forecast. Overall, zonal flow over the region as Bermuda high
begins to build in the mid-levels. By mid-week the western
trough is forecast to transition into the east as a surface
front will move from the Great Lakes towards the Northeast
around Wed/Thurs. Still some issues with the timing of the front
as a surface wave may develop along it, which could slow it
down a bit. This appears to be more inline with the EC/GEFS and
ECENS. Otherwise, northwest flow behind the front could result
in several clippers for next weekend.


Monday... High confidence.

Westerly flow across the region as high pressure builds south of the
region. Developing LLJ of near 40 kts will develop with high
pressure to the south and quick moving wave to the north. This will
make conditions a bit gusty at times. As surface high pressure moves
farther to the east, winds will begin to back resulting in WAA.
Surface temps could reach into the mid 50s on Monday with full
mixing. Otherwise dry weather will prevail.

Tuesday...High confidence.

More of a transition day for Tuesday as high pressure moves eastward
as upper level trough approaches. Southwest flow aloft will help
saturate the profile. Guidance does show a weak wave developing a
coastal low but appears to be just to far east to bring significant
rainfall to the region. Depending on when this occurs, we could see
a few flakes north of the Pike but confidence is low on this
occurring. For now expect a few showers and clouds on Tuesday.

Wednesday into Thursday... Moderate confidence.

Main weather produce for the long term will occur Wed into Thursday
as upper level trough approaches the region. Warm front ahead of the
system will bring some showers to the area as temperatures rise well
above average.

Upper level low will move from the Plains towards northern Maine.
This will drag a potent cold front through the region. Good
agreement amongst the guidance with this system, just some issue`s
with the exact timing of the front. Trended towards the slower side
as there is the potential for a secondary low to develop along the
front. This is more inline with the ensembles.

This is an anomolous system with PWATs 3 STD above normal as Gulf
moisture is tapped out ahead of the frontal passage. Heavy precip is
a possibility if secondary low does develop bringing the better
dynamics over southern New England. Also have noticed that there is
a potent southerly LLJ out ahead of this system with 925 mb LLJ
increasing to near 50-60 kts. If heavy rain does develop then we
could tap into these stronger winds as the system moves through.
Lastly appears that there is some elevated instability so have kept
with iso thunder in the forecast. Still a lot of details to work
out, but a system to watch in the coming days.

High confidence in above average temperatures with a non-diurnal
trend Wednesday night. Went several degrees above guidance and could
still be a bit low.

Friday and beyond... Moderate confidence.

As the cold front passes through, northeast winds take a hold of the
region. Models appear to be inline with a few shortwaves/clipper
systems moving through the flow. So some snow showers are certainly
possible as temps drop back to seasonable.


Forecaster Confidence Levels...

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

Short Term /through Sunday Night/...

Through 00z...Mix of VFR/MVFR cigs this afternoon, but IFR
stratus and patchy fog expected to develop along the south coast
and Cape/Islands toward 00z.

Tonight...Moderate confidence.
Widespread showers and isold t-storms will move through
western New Eng 00-02z then diminish as it moves into eastern
New Eng 03-06z. Brief heavy rain and gusty winds possible with
any t-storms in western New Eng. Precip may end as brief snow
showers in the Berkshires 03-06z. IFR/MVFR cigs with patchy
fog will improve to VFR after cold fropa and wind shift to W/NW
02-06z. W/NW gusts to 30 kt developing after the wind shift,
with G35 kt possible over higher terrain.

Sunday...High confidence.
VFR with sct-bkn cigs 4-5k ft. W/NW gusts to 30 kt, higher gusts
possible over higher terrain in the morning.

Sunday night...High confidence.
VFR. Diminishing W wind becoming SW overnight.

KBOS TAF...Moderate confidence through this evening, then high
confidence in improving conditions overnight.

KBDL TAF...Moderate confidence through this evening, then high
confidence in improving conditions late this evening.

Outlook /Monday through Thursday/...

Monday...High confidence. VFR with westerly wind gusts near 20-30

Tuesday...Moderate confidence. Generally VFR with MVFR conditions
possible south of the Pike.

Wednesday...Moderate confidence. MVFR to possible IFR in -SHRA.


Forecaster Confidence Levels...

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

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

Tonight...Moderate confidence.
Southerly winds shift to W/NW behind a cold front 03-06z.
Increasing post-frontal winds with a few marginal gale force
gusts to 35 kt expected. Will continue gales for most of the
open waters.

Sunday...High confidence.
W/NW gusts to 30-35 kt, especially during the morning with a
gradual diminishing trend during the afternoon.

Sunday night...High confidence.
Diminishing W winds in the evening becoming SW overnight.
Another surge of 25-30 kt gusts expected toward daybreak.

Outlook /Monday through Thursday/...

Monday...High confidence. Improving conditions on Monday with gusts
near 20 kts and seas beginning to relax as high pressure builds over
the southern waters.

Tuesday into Wednesday...Low confidence. Wind and seas will be below
SCA for Tuesday. Approaching system to the west could see lower
vsbys in rain and fog. Seas build late Tuesday night into Wednesday
as low pressure system approaches. There is the potential for
southerly gales across the waters.


We will need to monitor rising water levels across southern New
England into early next week. Much, if not all, of our snowpack
has, or will have, melted. There is still much more snowpack
upstream, over northern new England, that will push into the
headwaters and head downstream. Some river levels could approach
action stage.


BOS 73/2017 - previous record 70/1985
PVD 72/1985 - topped off at 71 degrees (no record)
BDL 73/1985 - topped off at 72 degrees (no record)
ORH 69/2017 - previous record 67/1985

BOS   49/1930 - bottomed out at 46 (no record)
PVD   45/2017 - ties previous record of 45/1984
BDL   43/1981 - bottomed out at 42 (no record)
ORH   48/2017 - previous record 46/1985

BOS 65/1930 * broken 69 degrees
PVD 69/1976
BDL 70/1976 * tied 70 degrees
ORH 64/1976 * broken 65 degrees

BOS   46/1891
PVD   45/1930
BDL   45/1930
ORH   37/1996, 1984, 1976

BOS   Max Dew Point 54 ties highest for date set in 1985
PVD   Max Dew Point 53 is highest for date. Previous high 50/1990
BDL   Max Dew Point 54 is highest for date. Previous high 49/1990
ORH   Max Dew Point 53 is highest for date. Previous high 48/1985


MARINE...Gale Warning from 2 AM to 11 AM EST Sunday for ANZ231>235-251.
     Small Craft Advisory from 11 PM this evening to 7 PM EST
     Sunday for ANZ230-236.
     Small Craft Advisory from 11 PM this evening to 10 PM EST
     Sunday for ANZ237.
     Gale Warning from 2 AM to 2 PM EST Sunday for ANZ250-254>256.


LONG TERM...Dunten
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