Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kbox 250915 
afdbox

Area forecast discussion
National Weather Service Taunton Massachusetts
415 am EST Sat Feb 25 2017

Synopsis...
mild air remains over the region today. A strong cold front
will cross the region tonight, bringing showers and a low
chance for thunderstorms as this front passes. Blustery
conditions with temperatures close to seasonal normals 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.

&&

Near term /until 6 PM this evening/...
low clouds and fog over the region will diminish during the
morning. After the cloudy start, expect partial clearing later
this morning and for part of the afternoon.

Digging shortwave over the Great Lakes will eject northeast into
Canada. The digging turns the upper flow more northerly. A cold
front over the eastern Great Lakes will sweep east across New York and
PA during the day. Precipitation along the front will mostly
move north/northeast into Canada and only slowly shift east.
Best chance of showers from this front will be late afternoon
and in western Massachusetts/western CT.

Model guidance has been consistantly cool compared with
verification the past couple of days. Temps at 925 mb support
Max sfc temps in the mid to upper 60s. The warmer guidance
members also aim at this range.

&&

Short term /6 PM this evening through 6 PM Sunday/...
the cold front arrives in the Hudson Valley around 6-7 PM and
crosses into western New England around 8-9 PM...central
sections 9-10 PM...and eastern New England 10 PM to midnight.
This front will be supported by the sharp upper shortwave.
Airmass stability will decrease through the evening...for
example, totals will climb into the lower 50s. This supports the
concept of sufficiently unstable conditions for a few
thunderstorms as the cold front approaches and moves through.
The greatest risk for tstms would be in western Massachusetts and western
CT where the low level inflow is least maritime.

Low level southerly winds will increase during the afternoon, so
that by evening we expect a 50-knot jet at or below 5000 feet.
Confidence is not high as to how much of that wind may be
brought to the surface in gusts during showers/tstms, but its
presence suggest a chance of strong wind gusts this
evening...possibly isolated damaging wind. Greatest risk would
again be in western areas early tonight.

Precipitable water fields continue to advertise values a little
over an inch, which is well above normal. But this is a narrow
and fast- moving zone, so while showers may be briefly strong,
total amounts should be 0.50 inches or less.

Colder air rushes in behind a cold front. It will be a race
between the cold air and the departing showers, but a brief
changeover to snow is possible at the end. Any accumulations
should be limited, generally less than an inch and mainly over
the higher terrain of the Berkshires and Worcester Hills.

Finally, the colder air advection behind the front will bring
mixing of strong west-northwest winds aloft to the surface late at night.
Wind gusts at that time will have a potential of reaching 30-35
knots.

Sunday...high confidence.

The shortwave trough moves offshore Sunday morning. The last of
any pcpn should end by that time. So Sunday shapes up to be a
dry day as high pressure builds in from the west.

Cold advection continues during the day. Mixing due to this
advection will tap winds aloft of 25-35 knots and possibly a
few areas of 40 knots. These winds will diminish during the
afternoon as the high pressure area approaches.

Temps aloft chill behind the front, but hover on Sunday at
levels that support sfc Max temps around 40 or the lower 40s.
Given the morning temps starting in the 30s, we have forecast
Max temps in the upper 30s to mid 40s.

&&

Long term /Sunday night through Friday/...

Highlights...

* 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 food
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.

Details...

Monday... high confidence.

Westerly flow across the region as high pressure builds south of the
region. Developing low level jet 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 warm air advection.
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 Standard 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 low level jet out ahead of this system with 925 mb low level jet
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.
&&

Aviation /09z Saturday through Wednesday/...
forecaster confidence levels...

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

Short term /through Sunday/...

Today...moderate confidence.

Stratus lingers across all areas early this morning, with cigs
between 500 and 1500 feet. Lowest cigs are along the South
Coast. Vsbys, after taking a dramatic dip at 10 PM, improved
overnight to either MVFR or better. Expect the low cigs to
continue through sunrise and then break. While low vsbys will be
spotty, their potential will linger until sunrise as well. Most
areas will have unrestricted vsbys by morning.

VFR continues through most of the day. Increasing south winds at
2000-4000 feet through the day, with 50 knots possible over the
CT valley by 5-6 PM. This may bring low level wind shear to that
area. Showers and scattered thunder will approach western areas
after 21z/4 PM, with IFR conditions possible in some showers.
Some of the heavier showers/storms could bring strong wind gusts
to the surface.

Tonight...moderate confidence.

A cold front sweeps west to east across the region between 6 PM
and midnight. Showers and widely scattered thunderstorms are
possible. This means conditions may briefly lower to IFR in any
showers or thunderstorms. We continue to expect low level wind
shear as well as a chance of strong wind gusts with
showers/storms as that 50 knot low level jet sweeps across ahead
of the cold front. The best chance for this will continue to be
in western Massachusetts and CT early in the night.

Behind the cold front, winds will shift from the west and west-
northwest. Colder air moving in behind the front will allow
strong west-northwest gusts to work in by late night, with speeds of 30 to
35 knots possible. The colder air may also bring a brief change
from rain to snow at the western edge of the precipitation.

Sunday...high confidence.

VFR. West-northwest winds will continue to gust 25-35 knots.
There are pockets of 40 knots shown in our forecast guidance,
so a few of these stronger winds are possible. Winds will
diminish by mid to late afternoon.

Kbos taf...moderate confidence in taf through 12z then high
confidence in taf through 25/22z. Moderate confidence after 22z.

Kbdl taf...moderate confidence in taf through 12z then high
confidence in taf through 25/22z. Moderate confidence after 22z.

Outlook /Monday into Wednesday/...

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

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

Wednesday...moderate confidence. MVFR to possible IFR in -shra.

&&

Marine...
forecaster confidence levels...

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

Short term /through Sunday/...high confidence.

Today...high confidence.

Increasing southerly winds through the day, with gusts to 25
knots mid to late afternoon. Seas will increase through the day
with 5 to 6 foot heights on the southern waters by mid to late
afternoon.

Tonight...moderate confidence.

A cold front sweeps across the waters the first part of the
night. This will bring showers and a widely scattered
thunderstorm. The showers may tap strong winds at 2000 to 4000
feet above the surface and bring them to the surface in strong
southerly wind gusts. Seas build to 5-8 feet on the exposed
waters of the south and the outer waters of the east.

Behind the front, winds shift from the west or west-northwest
and bring cooler air. Winds late tonight should gust 30 to 35
knots. Seas will continue at 5 to 8 feet.

Sunday...high confidence.

West-northwest winds continue to gust 30 to 35 knots during the
morning and early afternoon. Winds may slowly diminish during
the later afternoon. Seas will linger at 5 to 8 feet on the
exposed waters.

Outlook /Sunday night through Wednesday/...

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
Small Craft Advisory 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.

&&

Hydrology...
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.

&&

Climate...
record high temperatures for yesterday
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

Record high min temperatures for yesterday
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

Record high temperatures for today
bos 65/1930
pvd 69/1976
bdl 70/1976
orh 64/1976

Record high min temperatures for today
bos 46/1891
pvd 45/1930
bdl 45/1930
orh 37/1996, 1984, 1976

Dew points of note for yesterday
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

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...dense fog advisory until 7 am EST this morning for maz020>024.
Rhode Island...dense fog advisory until 7 am EST this morning for riz002>008.
Marine...Gale Warning from midnight tonight to 7 PM EST Sunday for
anz231>235-237-250-251-254>256.
Small Craft Advisory from midnight tonight to 7 PM EST Sunday
for anz230-236.

&&

$$
Synopsis...wtb/dunten
near term...wtb
short term...wtb

National Weather Service Glossary of Abbreviations