Area Forecast Discussion
Issued by NWS Boston, MA

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000
FXUS61 KBOX 242212
AFDBOX

Area Forecast Discussion
National Weather Service Taunton MA
512 PM EST Fri Feb 24 2017

.SYNOPSIS...
High pressure over the Atlantic Ocean will maintain dry and
unseasonably warm conditions through Saturday. A strong cold
front will cross the region Saturday night, bringing showers
and areas of fog. There will be a low chance for isolated
thunderstorms as this front passes. Blustery conditions with
temperatures close to seasonal normals expected for Sunday and
Monday. A couple of weather systems will bring periods of wet
weather Monday night into Thursday. Colder air looks to return
late next week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
*** Record Warmth Across Much of Southern New England ***

This afternoon...adjusted temperatures for this afternoon one
last time based on observed trends. Wind direction will be key
to see if Providence can tie their highest February max
temperature. At last check, they were still one degree shy.

Tonight...Expecting the unseasonably mild weather to continue.
Min temperatures tonight should range about 25 to 30 degrees
above normal.

Not seeing a lot of snowpack left in visible satellite imagery
this afternoon. However, whatever is left will certainly
continue to melt. This, combined with a persistent south wind,
will keep the lowest levels of the boundary layer fairly humid.
This is turn should at least lead to areas of fog. Also
expecting some stratus to develop, with a fairly strong
inversion developing.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Not much change to expectations during this period.

Low clouds and areas of fog likely to start Saturday. This will
limit sunshine for a while, resulting in lower max temperatures,
which will still be well above normal. Guidance has not been
handling the warmth the past couple of days very well, so kept
the trend of going a couple degrees higher than the warmest
guidance.

Still thinking a strong cold front will move across southern
New England Saturday evening, about the same time as a potent
mid level shortwave. Mid level lapse rates should be more
unstable than moist adiabatic. So despite a climatologically
unfavorable time, cannot completely rule out the possibility for
a few thunderstorms during the evening and overnight hours. The
greatest risk for thunderstorms would be across western MA and
northern CT.

Higher temperatures will lead to greater mixing depth of the
boundary layer. This should lead to more gusty southwest winds
of 25 to 30 kt, particularly toward the coast and over the
coastal waters. Any convection could bring stronger gusts to the
surface across the interior, too.

Precipitable water values continue to show just over an inch,
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 late Saturday night 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 WNW winds aloft to the surface. Wind gusts will
have a potential late Saturday night of reaching 30-40 knots.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...

Highlights...

* Blustery and more seasonable temperatures Sun and Mon
* Low pressure will bring scattered rain and/or snow showers Tue
* Another low passes N of New England with rain showers possible
  Mon night through Wed night
* A cold front may cause rain showers to mix or changing to
  snow showers Thursday

Overview...

Noting rather good agreement with the 12Z model suite on
development and movement of weather features across the region
into Tuesday. Beyond this, model solutions diverge, mainly due
to continued progressive upper level steering flow across the
lower 48, causing timing and track issues amongst the individual
models. Appears the 12Z GFS is on the fast side of the guidance
in moving systems along in the fast flow.

Overall, looks like temps will continue to run warmer than
seasonal normal, with the mildest temps around the Mon-Wed
timeframe at this point. Signals beyond this appears to see a
return to near or below normal temps by late next week. However,
timing and track of the systems during that timeframe remain in
question due to the fast steering flow aloft.

Details...

Sunday...High confidence.

H5 trough pushes quickly offshore Sunday morning. Any leftover
rain and/or snow showers over E coastal areas should be offshore
by 13Z. High pressure ridge will approach from the W by Sunday
evening.

General W wind flow at the surface and aloft moves in. Noting
H85 low level jet at 40 kt, and 30-35 kt below to H95. Excellent
low level mixing in place with lapse rates at 9-10C/km up to
H85. So, will likely see gusts up to up to 30-35 mph, possibly a
bit higher across the higher inland terrain as well as along
the coast.

Even though colder air works in aloft, temps look to top off
milder than seasonal normals. Highs will be mainly in the 40s,
though could reach to around 50 in the coastal plain and lower
CT valley. However, with the blustery winds, it will feel colder
with wind chills in the 20s across the higher terrain and 30s
elsewhere.

Monday...Moderate to high confidence.

High pressure ridge builds offshore as center of the associated
high will push off the mid Atlantic coast. Winds back to SW
during the day on the backside of the high. Another dry day with
some gusty winds, up to 20-30 mph possible around midday or
during the afternoon, highest along the S coast, Cape Cod and
the islands.

Mid and upper level moisture will start to work in aloft, so
clouds will be increasing during the afternoon. Highs will range
from the mid 40s across the higher inland terrain to around 50
across the coastal plain.

Monday night through Wednesday...Moderate confidence.

As mentioned above, model solutions begin to diverge during
this timeframe. Noting high pressure settling off the SE U.S.
coast. Mid level steering currents shift to a more SW direction
with broad ridging over eastern Canada into the western Atlc.
Noting weak short waves in this flow, with a wide variety of
tracks for each individual wave.

At the surface, will see low pressure wave shift NE in the mid
level flow late Mon night and Tue. Most of the energy remains
just offshore, but will see slug of moisture cross the region.
have carried slight chance to chance POPs, with the best chance
for showers during Tuesday. Looks like models signal mainly
rain, but could see some mixed rain/snow showers at the onset of
precip overnight Mon night. QPF values on order of 0.1 to 0.2
inches during Tuesday. Mild air remains in place on Tuesday, so
highs will be in the mid 40s to around 50.

Precip will linger Tue night as first wave moves off the Mass
coast into the Gulf of Maine. However, another low looks to
cross out of the Great Lakes into southern Quebec late Tue night
into Wed bringing another slug of precip to the region. SW
winds remain in place, so temps will not fall much Tue night.
Lows will be mainly in the 30s. Could see a brief period of
mixed rain/snow showers along the Mass/NH border overnight.

On Wednesday, the low shifts E-NE, but another trailing front
will keep the chance for precip across the region into Wed
night, but timing is in question. Another question is whether a
secondary low will form along this front as it pushes toward the
mid Atlantic coast or even a bit further north. This could
delay the exit of the precip. Expect highs in the upper 40s to
mid 50s, so expect rain showers to continue.

Thursday...Low confidence.

Low pressure looks to push into eastern Canada, with trailing
cold front passing offshore. May see lingering rain and/or snow
showers before ending. Timing of front`s exact track exiting the
region still very much in question.

12Z model suite and ensembles signaling colder air working
across the region by Thu night. Temps will be cooler than
earlier in the week, but will be close to seasonal normals.

Friday...Low confidence.

For now, should see mainly dry but cold and blustery
conditions. Highs may run about 5 degrees below seasonal
normals.


&&

.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...

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

Short Term /through Saturday Night/...

Through 00Z...High confidence. VFR.

Tonight...Moderate confidence. VFR with areas of IFR/LIFR
developing in areas of fog. patchy LLWS possible as a southwest
low level jet develops over southern New England. Greatest risk
for LLWS north and west of KLWM-KORH-KBDL.

Saturday...Moderate confidence.

Lingering IFR in morning fog, otherwise VFR. Showers approach
from the west and are most likely between 21Z and 03Z in the
west, and between 00Z and 06Z in the east. Conditions may
briefly lower to IFR in any rain showers. Isolated
thunderstorms are possible as this band of showers moves
through. Rain may change to snow across the higher terrain as
it tapers off Saturday night.

More LLWS is possible in the evening with S-SW winds at 40-50
knots at 2000-3000 feet AGL. Winds shift from the west during
the early night as a cold front sweeps through from west to
east. WNW winds will become gusty overnight with gusts to 30 to
35 knots possible.

KBOS TAF...High confidence in TAF through 25/04Z. Moderate
confidence in TAF after 25/04Z.

KBDL TAF...High confidence in TAF through 25/04Z. Moderate
confidence in TAF after 25/04Z.

Outlook /Sunday through Wednesday/...

Sunday...High confidence. VFR. W-NW wind gusts to 25-35 kt.

Monday...High confidence. VFR. W-SW winds gusting to 20-25 kt,
highest along the coast and over the higher terrain, diminishing
Mon night.

Monday night-Wednesday...Moderate confidence. Areas of MVFR
conditions possible in -SHRA and/or -SHSN.

&&

.MARINE...
Forecaster Confidence Levels...

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

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

Tonight...Winds and seas remain relatively light. South to
southwest winds continue.

Saturday...Moderate confidence.

A cold front sweeps across the waters Saturday evening and
early night with showers, and perhaps isolated thunderstorms.
Strong winds aloft may produce a couple of strong wind gusts in
any showers and storms. Winds shift behind this cold front.
Winds from the west after midnight will have potential gusts of
30 to 35 knots. This would be borderline conditions for gales
toward Sunday morning.

Outlook /Sunday through Wednesday/...

Sunday...High confidence. W winds gusting up to 25-30 kt. Some
gust up to 35 kt possible mainly over the open waters. Gale
watch in effect. Seas up to 6-8 ft. Winds and seas should slowly
diminish Sun night. Good visibilities.

Monday...High confidence. Winds back to SW gusting up to 25-30
kt highest on the eastern outer waters. Seas remain around 5 ft.
Will likely hold on to small craft conditions through Mon night
over the outer waters. Good visibilities.

Tuesday through Wednesday...Low to moderate confidence. Expect
E-SE winds gusting to 20 kt on Tue, then shifting to SW on
Wednesday. Gusts will increase to around 25 kt late Wed/Wed
night, along with seas building to at or above 5 ft over the
open waters. With approaching system to the west could see lower
vsbys in rain and fog.

&&

.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 TEMPS FOR TODAY
BOS   73/2017 - previous record 70/1985
PVD   72/1985 - topped off at 71 degrees
BDL   73/1985 - topped off at 72 degrees
ORH   69/2017 - previous record 67/1985

RECORD HIGH MIN TEMPS FOR TODAY
BOS   49/1930 - bottomed out at 46 this morning (no record)
PVD   45/1984 - bottomed out at 45 this morning
BDL   43/1981 - bottomed out at 42 this morning (no record)
ORH   46/1985 - bottomed out at 48 this morning

RECORD HIGH TEMPS FOR SATURDAY
BOS   65/1930
PVD   69/1976
BDL   70/1976
ORH   64/1976

RECORD HIGH MIN TEMPS FOR SATURDAY
BOS   46/1891
PVD   45/1930
BDL   45/1930
ORH   37/1996, 1984, 1976

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Watch from late Saturday night through Sunday evening for
     ANZ230>237-250-251-254>256.

&&

$$
SYNOPSIS...Belk/EVT
NEAR TERM...Belk
SHORT TERM...Belk
LONG TERM...EVT
AVIATION...Belk/EVT
MARINE...Belk/EVT
HYDROLOGY...Belk
CLIMATE...Staff


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