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Area forecast discussion 
National Weather Service Taunton Massachusetts
722 PM EDT Wednesday Apr 1 2015

high pressure and chilly overnight. Turning milder into Thursday
with breezy southwest winds. Rain chances increase towards Friday
morning with the threat of heavy rain and thunderstorms as waves
of low pressure slide across a slow moving cold front. Dry and
chillier weather follows by late Saturday into Saturday night.
Fast moving low pressure may bring a few rain and/or snow showers
to the region Sunday into Sunday night. Periods of unsettled
weather possible for the first half of next week...but confidence
is quite low.


Near term /until 6 am Thursday morning/...
730 PM update...made adjustments to the temperatures and dewpoints
to bring them back in line with current trends. Otherwise...the
forecast was on track.

Winds taper as high pressure pushes into the region. Anticipate
quiet weather consisting of mostly clear conditions and light /
variable winds. While some increasing clouds late...expecting an
opportunity for radiational cooling. A consensus blend of MOS
guidance...nudged temperatures down a few degrees for areas which
notoriously radiate out and valley locations subject to cold-air
drainage /katabatic flow/.


Short term /6 am Thursday morning through Thursday night/...
*/ Thursday...

Warm front lifting NE across the region along the nose of return
warm-moist SW-flow along the west-periphery of the low- to middle-level
ridge axis pushing east. With middle- to upper-level support lacking...
feel a dry forecast prevails. Though there is some hint of low-
topped showery weather the better chances of which are along the west-
slopes of higher terrain...synoptic forcing and dynamics are largely
absent...mainly found northwest across Canada.

Onshore flow increasing out of the S in response to an enhancing
pressure-gradient with the approaching low and high pressure pushing
offshore. Increasing SW-flow aloft beneath an anticipated boundary-
layer inversion at 850 mb temperatures warm to +6-8c with h925 +2-4c.
But with clouds remaining a nuisance mainly over the north/west of New
England...whereas S/east remain mostly clear...the high-angle of the
early April sun will likely allow for highs up around the low- to
mid-50s. The warm-spots likely in the lower CT-valley...Merrimack
River valley...and interior east/southeast Massachusetts. Cooler along the S-shore and
out on Cape Cod with the onshore SW-flow off the much cooler waters.

*/ Thursday night...

Frontal boundary sweeps S across New England towards Friday morning.
Nearly parallel flow along the boundary. Attendant synoptic forcing
and dynamics lacking. There is little indication of convergence nor
deep-layer ascent. Though anomalous precipitable waters on the order of +1-2 South Dakota as
consensus forecast guidance suggests 1.00-1.25 inches...without much
forcing / lift...can not efficiently get the atmosphere to rain

So while wet weather is likely...expect just showers. No thunder and
nothing pronounced. Scattered activity. No flooding concerns. Just
an abundance of clouds and overall a mild night the likes we have
not seen since Thanksgiving 2014 for Boston / Providence...since
late October for Hartford / Worcester...using 45 degrees as the
threshold. Amazing! Looking at lows around the low- to mid-40s.

Will need to monitor closely for the presence of dense fog. Higher
dewpoint air over the colder ocean...and relatively colder ground
with lingering snowpack...will likely result in the development of
some dense fog. Though milder conditions ushered by breezy light snow shower
flow. Will this deter fog development remains to be seen. Of some
certainty will be the expectation of breezy high dewpoint air
along with wet-weather will allow for faster erosion of any left-
over snow. Perhaps we can finally say goodbye to the remnants of
winter. Right now we have a fog-free forecast as neither climatology nor
MOS-guidance suggests fog mostly due to anticipated breezy winds.
Again...will just have to monitor.

SW-gusts 25-35 miles per hour across S/southeast coastal New England...with 15-25
miles per hour gusts across the interior.


Long term /Friday through Wednesday/...
* quite unsettled weather expected through the long term
* highest confidence in periods of showers Friday into Sat am
* rain/snow showers possible again sun
* low confidence on unsettled weather pattern next week

Models are not in very good agreement at all for much of the
forecast period. The European model (ecmwf) in particular seems to be somewhat of
an outlier. However...confidence is rather low through the period
but especially next week. Somewhat higher confidence in the
forecast through Sunday...though there are still some model
differences that could yield different forecast results.

Friday through early Saturday...a shortwave trough and its attendant
low pressure system will move over the northeastern United States...
bringing widespread showers to the area. The 01/12z GFS/NAM bring
this low pressure system up from the lower MS valley are through
southern New England. The 01/00z European model (ecmwf) brings the low pressure up
through northern New England. This would mean a difference in
temperature profiles as well as wind directions during the day.
However...Don/T believe there is a significant enough difference
to result in a change of ptype from rain. Leaning more towards the
GFS/NAM solution.

Warmest day of the week should be Friday when temperatures will actually
reach or possibly even climb above normal. This may result in a
few locations reaching 60+ degrees for the first time this Spring.

Rest of Saturday...temperatures fall back below normal behind the
cold front that trails this low pressure system. Much of the day
should be dry prior to another front approaching the area.

Sunday...a quick cold front will move through the region bringing
another round of rain and possibly snow showers to the region.

Monday through Wednesday...a very unsettled pattern with low
confidence in the details and timing of the forecast. There is
potential for rain showers each day in one model or another but not
expecting a washout any one day nor through the entire period.
Temperatures will be fighting between cooler air to the north and
warmer air to the south. Given the pattern as of late...expect
the cooler air will likely win out. Will go with a blend of model
guidance for this time period.


Aviation /00z Thursday through Monday/...
forecaster confidence levels...

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

Short term /through Thursday night/...

Tonight into Thursday...high confidence.

VFR. Vrb winds overnight increasing out of the SW through the day
Thursday with gusts up to 25 kts along the S-shore by evening.
Some low-end VFR ceilings mainly across north/northwest Massachusetts around Thursday morning
into midday.

Thursday night...moderate confidence.

Low-end VFR / MVFR ceilings with scattered -shra. Continued blustery SW-flow
with gusts 15-20 kts across most of the terminals...25-30 knots over
S/se-coastal New England. Low confidence at this time...but dense
IFR fog possible. Low level wind shear likely as SW-winds at 2 kft will be 40-50

Kbos taf...high confidence. Gusty presently...but should see these
gusts drop off into evening.

Kbdl taf...high confidence. Gusty presently...but should see
these gusts drop off into evening.

Outlook...Friday through Monday...

Friday through Saturday morning...moderate confidence. MVFR
conditions are likely in rain showers. IFR conditions are
possible Friday night in fog.

Saturday afternoon and night...moderate confidence. Mainly VFR.

Sunday and Monday...low confidence. Mainly VFR. Periods of
MVFR/IFR in rain/snow showers.


forecaster confidence levels...

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

Short term /through Thursday night/...

Tonight...high confidence.

High pressure building across the waters. Winds becoming light and
variable. Seas relax.

Thursday...high confidence.

Winds increasing out of the SW through the day with gusts up to
25 kts along the S-shore by evening. Swell building resulting in
seas in excess of 5-feet beginning by afternoon into evening.

Thursday night...moderate confidence.

Continued blustery SW-flow with gusts 25-30 knots over S/southeast waters.
Low confidence at this time...but dense IFR fog possible. Winds
may limit fog development. Will need to closely monitor. Low
confidence concerning gales but could not rule out an intermittent
gale-force gust at times. Seas building 6-8 feet on the outer
waters...including Rhode Island / bi sound. Showery weather...not thinking
any heavy rain / thunderstorms at this time.

Outlook...Friday through Monday...

Friday through Saturday...seas increase as low pressure approaches
and then moves over the waters. Southwesterly winds 15 to 20 kts
shift to the northwest Saturday morning. Gusts up to 30 kts are
possible at times. Small craft advisories are likely for both
winds and seas on all the waters with a low probability of gales
being necessary for the outer waters for a period Saturday.

Saturday night through Sunday...seas diminish...but remain above 5
feet on the outer waters. Northwesterly winds diminish but remain
above 25 kts for most of the waters. Small craft advisories will
likely be necessary.

Monday...seas fall below 5 feet as a brief period of high pressure
builds over the waters. Southwesterly winds continue to diminish
and slowly shift to the southeast.


Box watches/warnings/advisories...
Rhode Island...none.
Marine...Small Craft Advisory from 2 PM Thursday to 6 am EDT Friday for


near term...rlg/sipprell
short term...sipprell
long term...rlg

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