Area forecast discussion
National Weather Service Taunton Massachusetts
1056 PM EDT Sat may 25 2013
Synopsis...
low pressure in the Gulf of Maine will slowly move northeastward
tonight. Some improvement is likely Sunday as this low departs
into northern New England. Mainly dry weather is anticipated with
moderating temperatures Monday into Tuesday. A warm front will move
through Wednesday bringing some showers and thunder. Expect warm
and muggy conditions by the end of the work week.
&&
Near term /until 6 am Sunday morning/...
1050 PM update...mainly brough near-term forecast conditions in
line with observed trends. No major changes to the forecast.
Previous discussion...
Showers and drizzle continue. The surface low was off Portland
and the upper low overhead. As these shift northeast...the coldest
air aloft will move over southern New England. Model soundings
suggest that rain in the higher terrain may mix with or change
over to snow in the heavier showers. The best chance for this to
occur exists at elevations greater than 1000 feet. Given that its
late may...temperatures at the surface and on the ground are too
warm for any appreciable accumulations. Elevated surfaces such as
trees and power lines may see a dusting of snow. Low temperatures
are expected to be 10 to 15 degrees below seasonal normals.
&&
Short term /6 am Sunday morning through Sunday night/...
Sunday...leftover showers will end from south to north during the
day as low pressure moves into the Maritimes. Clouds will remain
for most of the day as northwest winds pick up. Expecting gusts up
to 30-35 miles per hour...especially across central and western areas. Will
remain cool with highs again 10-15 degrees below normal.
Sunday night...should see clearing skies as high pressure starts
to build into southern New England. Winds will stay up enough to
prevent optimal radiational cooling so temperatures won't be as cool as
tonight but will still be 5 to 10 degrees below normal.
&&
Long term /Monday through Saturday/...
big picture...upper low over the northeast USA migrates northeast
through the Maritimes. Upper high pressure over the plains shifts
east for the latter half of the week. Pacific upper low digs over
The Rockies midweek...then ejects through the northern plains by
next weekend.
Model preferences...upper contour fields are similar for much of
the week. Minor differences in handling the ejecting Pacific low
upstream late week. We used blends of HPC/gmos and GFS/European model (ecmwf) data
as available.
The dailies...
Monday-Tuesday...upper trough shifts east Monday but still
cyclonic flow aloft as the surface high builds in. Limited
moisture around 850 mb should support some diurnal cloud
development...but not deep enough for any showers. Monday should
be a dry day with at worst partly cloudy skies. Of more concern
are the temperatures. Both mav and met guidance show highs in the
middle 70s pvd-bdl and low 70s bos...while model temperatures at the top of
the mixed layer support values of 65-70. Either the model temperatures
aloft are wrong...the projected mixing depth is wrong...or MOS is
wrong. We favored a blend that edges toward the cooler values with
a range in the upper 60s to low 70s.
Clear skies and light winds Monday night...dewpoints 35-40. Could
be some frost in the Berkshires and Monadnocks but elsewhere temperatures
should bottom out in the upper 30s to middle 40s.
High pressure overhead Tuesday with temperatures aloft warming...values
around 9-10c support maximum temperatures 75-80. Cooler at the coast as the
light flow will allow for developing sea breezes.
Wednesday...upper ridge will push warming temperatures into the region.
Warm front representing the leading edge of this warmer air moves
across New England late Wednesday/Wednesday night. This will
generate some showers...and stability parameters support potential
for thunder as well.
Thursday through Saturday...very warm air aloft with 850 mb temperatures
around 16c. Dewpoints are expected in the low to middle 60s. Mixing
should support maximum temperatures in the middle and upper 80s...dewpoints
point to humid air with night mins in the 60s. Shower potential
looks low Thursday and Friday. An approaching cold front may bring
a chance of showers Saturday especially north of the Mass Pike.
But the strength of the upper ridge may keep this front to our
north and preclude showers. So the precipitation forecast is low confidence
by next Saturday.
&&
Aviation /03z Sunday through Thursday/...
forecaster confidence levels...
Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.
Overview...
Tonight...moderate confidence. Snow may mix in with the rain
across the higher terrain in western Massachusetts and southwest New Hampshire. Showers
will keep conditions variable across the region. MVFR ceilings over
the coastal plain and north of mass Route 2...MVFR/IFR visibilities along
the East Coast. VFR conditions possible elsewhere.
Sunday...moderate confidence. Precipitation tapers off from S-north
with VFR conditions most everywhere by late Sunday afternoon.
Sunday night...high confidence. VFR.
Kbos terminal...moderate confidence in taf. Low confidence in
overall timing.
Kbdl terminal...moderate confidence in taf. Low confidence in
overall timing.
Outlook...Monday through Thursday...
Monday through Thursday...generally VFR. Early morning IFR
possible in fog and low clouds. Local MVFR ceilings/visibilities in
showers/thunderstorms Wednesday and Wednesday night. Sea breezes at the
coast Tuesday.
&&
Marine...
forecaster confidence levels...
Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.
Northwesterly winds and seas increase tonight into Sunday as low
pressure rotates in the Gulf of Maine and then moves into the
Maritimes Sunday. Small craft advisories are up for all marine
zones at some point through Sunday night. West-northwesterly winds
take awhile to kick up on the eastern waters so advisories begin
later over those interior zones where seas remain below 5 feet.
Winds will be stronger on the southern outer waters so have opted
for gale warnings across those waters...especially given the
busier Holiday weekend. Showers and fog may limit visibilities
through Sunday morning with showers tapering off Sunday afternoon.
Outlook...Monday through Thursday...
Monday through Wednesday...winds and seas below small craft
thresholds. South winds may gust near 25 knots nearshore of the
cape and islands Wednesday afternoon.
Thursday...southwest winds gusting near 25 knots nearshore of the
cape and islands. The southwest wind will build seas with 5-6 foot
values on the outer waters...possibly on Rhode Island and Block Island sounds
as well.
&&
Hydrology...
while there may be periodic heavier rain showers across southern
New England through early Sunday...not thinking it will be
persistent enough to result in flooding. Will have to monitor the
possibility of training cells though. No headlines planned at this
time.
&&
Tides/coastal flooding...
high astronomical tides are expected along the East Coast of
Massachusetts this weekend. At Boston...a high tide of 12.2 feet
will occur early Sunday morning at 12:12 am. After high tide this
afternoon...there was about a half foot of surge lingering at
Boston. With estofs indicating up to 0.7 feet surge...seems
reasonable that it could reach 13 feet even with minimal wave
action offshore. Confidence not high enough to issue a coastal
Flood Advisory especially being a marginal event but opted to
issue a coastal flood statement for the eastern Massachusetts
zones for the potential of some splashover.
&&
Climate...
several climate records could be reached over the weekend. While
Boston...Providence...and Worcester were several degrees over
their record low maximum temperature this afternoon...Hartford has
tied its record low maximum of 48 so far. If their temperature GOES up
even a degree the record set in 1967 will hold. However...think
theres a good chance that we will tie that record in Hartford.
Tonight...the forecast low at Worcester...34 degrees...would break
the current record low of 35 degrees set in 1992. The forecast
lows at Providence...Hartford...and Boston are within 2-3 degrees
of the previous records /see below/.
Hartford - forecast low - 39 record low - 36 (1992)
Providence - forecast low - 38 record low - 35 (1972)
Boston - forecast low - 41 record low - 39 (1882)
&&
Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
New Hampshire...none.
Rhode Island...none.
Marine...Small Craft Advisory until 4 am EDT Monday for anz232>235-237-
250-254.
Small Craft Advisory from 2 PM Sunday to 4 am EDT Monday for
anz230-231-251.
Small Craft Advisory until 9 PM EDT Sunday for anz236.
Gale Warning until 7 am EDT Sunday for anz255-256.
&&
$$
Synopsis...dunten/rlg
near term...Belk/rlg
short term...rlg
long term...dunten
aviation...wtb/dunten/rlg
marine...dunten/rlg
hydrology...staff
tides/coastal flooding...staff
climate...rlg
