Area forecast discussion
National Weather Service Taunton Massachusetts
1048 am EDT Wednesday may 22 2013
Synopsis...
a stalled front will move back north as a warm front today. Warm
and humid conditions continue into Thursday and Friday with
showers and scattered strong thunderstorms possible. Cooler and
less humid conditions are expected for this Holiday weekend as
high pressure builds across the northeast.
&&
Near term /until 6 PM this evening/...
Per 10 am observations...would place the stalled front near the
Massachusetts/New Hampshire border and extending across northeast mass. Upper flow is
mostly parallel to this front which would suggest little change in
position this afternoon. It/S possible for the front to drift
marginally north. Winds at Jaffrey are light southwest...which
also suggests some drift north. Temperatures and dewpoints are drifting
up at Hartford-Springfield and at Providence and expect this to
continue.
Signs of breakage in the cloud cover upstream...so that along with
advection there may also be some solar heating. Light flow at
surface will support seabreeze/onshore flow near the coast which
would keep temperatures lower near the coast. So we have held temperature
forecasts close to previous.
As for convection...another round of showers/thunder expected this
afternoon. Not much jet dynamics to support venting...but
favorable convective parameters in play. Best areas for
development would be along/west of the I-84/I-495 corridor. If the
front lingers near the mass border then New Hampshire would have less of a
chance...but if the front moves north then New Hampshire will be in play.
Storm Prediction Center has placed all of southern New England in a slight risk
area...so strong winds/hail are possible.
As mentioned before...the best advice is to keep an eye on the
sky and later forecasts if you will be outdoors this afternoon.
&&
Short term /6 PM this evening through 6 PM Thursday/...
tonight...more of the same tonight. Warm front continues to push
north as stronger south to southwest synoptic flow develops.
Decent instability persists through the night. So thinking we will
be seeing another night of isolated to scattered thunderstorms.
The greatest risk of these will be across the interior...away from
the stabilizing influence of the ocean.
Thursday...southern New England remains in the warm sector of a
low pressure moving from the Great Lakes into the Saint Lawrence
River valley. This low has a rather amplified upper system...so
its cold front will be slow to move across our region.
Expecting more rounds of showers and scattered thunderstorms.
Very humid airmass in place as well...with precipitable water
values around 1.7 inches. Will likely see some heavy downpours
with some showers...along with some hail and gusty winds. May not
quite reach severe thresholds as clouds will be more prevalent...
thus temperatures should be lower than Wednesday.
&&
Long term /Thursday night through Tuesday/...
highlights...
* scattered showers and thunderstorms Friday
* cooler and less humid for the weekend
Confidence level/model guidance...moderate confidence in overall
forecast. 00z models continue to slow down the elongated trough
moving across the eastern half of the Continental U.S.. there is still some
timing differences on when the system will push through the
northeast. Regardless appears that elongated trough will move into
New England eventually becoming a cutoff low by the weekend. This
low will eventually move into the Maritimes by the beginning of
the work week as high pressure moves in. Have high confidence that
precipitation will occur on Friday and cooler temperatures will dominate the
region for the weekend. Low confidence in forecast after Tuesday.
Details...
Thursday night into Friday...
upper level trough will push through the eastern Great Lakes
region eventually pushing a cold front through southern New
England. Models continue to slow the timing of the front down...so
believe that it move through sometime on Friday. Because of the
model difference have low confidence in timing.
Regardless...believe that showers and thunderstorms will move
through with temperatures near average. Cannot rule out a few strong
thunderstorms especially across regions south of the I-84
corridor. Models indicate some instability with about 25kts of
shear. Precipitable water values of over 1.5 inches leads forecaster to believe
that heavy downpours is the main threat...but with falling heights
as cold front approaches...small hail and gusty winds is not out
of the question. Any chance for strong storms to develop will
diminish after sunset as diurnal heating is lost.
Weekend...tricky forecast is playing out for the weekend. Models
have indicated that the elongated trough will cut off over the middle
Atlantic and slowly rotate over New England for the weekend. This
will allow for much cooler air...well below average and even has
slowed down the timing of precipitation. Believe that precipitation may linger
into Sat...but have low confidence that precipitation will occur on
Sunday. For now have continued with the slow down trend in the
forecast. Expect highs reaching into the middle to upper 60s with
lows dropping into the middle to upper 30s. If skies clear out as
this cold pool sits over US...there is a possibility that
frost/freeze headlines may be needed as the entire region is
officially in the growing season.
Monday and beyond...surface high pressure will be in control for
the first half of next week. This will help temperatures reach seasonal
conditions. Appears that there is limited moisture keeping the
forecast dry...however cannot rule out a spot shower or two...especially
if sea breezes develops.
&&
Aviation /14z Wednesday through Sunday/...
forecaster confidence levels...
Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.
Overview...moderate confidence in timing and areal coverage of
stratus and fog through this morning.
Midday/this afternoon...visibilities improving at most spots except
ack...but IFR ceilings lingering longer than expected. Clouds upstream
are showing breakage...so we should trend to lose the ceilings this
afternoon with heating allowing the ceilings to lift to VFR. Heating
will generate another round of showers/thunderstorms with best chances in
CT and north/west of Boston. The Storm Prediction Center has all
of southern New England in a slight risk area...so strong winds
and hail are possibilities especially after 2 PM through evening.
Tonight...moderate confidence in trends. Expect variable
conditions depending upon shower and fog development. Better shot
for IFR visibilities in fog along S coast on S-SW winds and mild temperatures
mainly after midnight. Scattered showers/thunderstorms across most of the region
though best shot across central and western areas...with MVFR-IFR
cigs/vsbys. May see local heavy downpours. Low confidence on
timing and placement.
Thursday...moderate confidence in trends. Very unsettled pattern
ahead of approaching cold front. Variable conditions between VFR
and MVFR/IFR in rain showers/tsra/patchy fog. Cold front crosses the
region Thursday night...so will see improving conditions across western
areas after midnight Thursday night...then into central sections after
06z-07z. May see SW wind gusting up to 20-25 knots during the day as
well. Winds shift to west-northwest across central and western areas after
midnight.
Kbos terminal...moderate confidence in trends...lower confidence
in timing of lower conditions and convection this afternoon.
Kbdl terminal...moderate confidence in taf...mainly due to timing
of convection this afternoon. Could see brief IFR in a band of
thunderstorms and rain.
Outlook...Thursday night through Sunday...
Thursday night into Friday...low confidence. Moderate confidence
on sea breeze developments. Very unsettled pattern with
variability between VFR conditions and MVFR/IFR conditions in
shra/tsra/fog. Improving conditions late Friday night into
Saturday morning.
Saturday-Sunday...high confidence. VFR.
&&
Marine...
forecaster confidence levels...
Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.
High confidence through tonight.
Increasing SW flow will result in seas building over the southern
coastal waters. Small Craft Advisory is in effect this afternoon
for some of the southern waters...expanding north overnight and
Thursday. Winds should continue to increase tonight into Thursday
as low pressure moves into the Great Lakes.
Expect low visibilities in heavy showers and patchy fog at times.
Isolated to scattered thunderstorms possible as well...especially
near shore.
Outlook...Thursday night through Sunday...
Friday...moderate to high confidence. Cold front will be slow to
clear the waters...so expect SW winds in place for a portion of
the day before shifting to west-northwest across the eastern waters.
The weekend...moderate confidence. Seas will remain above Small Craft Advisory for
most of the weekend especially for the outer waters. Gusty northwest behind the
front will bring gusts close to gale force Sat into Sat night.
Expect both seas and wind to slowly subside throughout the day
on Sunday.
&&
Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
New Hampshire...none.
Rhode Island...none.
Marine...Small Craft Advisory until 6 PM EDT Thursday for anz255-256.
Small Craft Advisory from 4 PM this afternoon to 6 PM EDT
Thursday for anz235-254.
Small Craft Advisory from 9 PM this evening to 6 PM EDT
Thursday for anz237.
&&
$$
Synopsis...Belk/dunten
near term...wtb/Belk/dunten
short term...Belk
long term...dunten
aviation...Belk/dunten
marine...Belk/dunten
