Area forecast discussion
National Weather Service Taunton Massachusetts
729 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/...
730 am update...
convection is finally dying down as it enters into already worked
over air. Expect precipitation to continue to move eastward and
dissipate. Temperatures are slow to rebound this morning...but with
winds south of the Pike already switching to the SW...expect temperatures
to jump later this morning. Otherwise bulk of the forecast remains
on track as strong to severe weather is still anticipated across
the western half of the region.
Previous discussion...
continuing to monitor waves of convection this morning. Latest
runs of the hrrr appear to have the best handle on these bands of
convection...although its timing was slow by a few hours. Leaned
heavily on the 05z hrrr with the appropriate timing adjustment for
the early morning forecast. Showers and thunderstorms are
reasonably holding together in a high shear/Low Cape environment.
Later today...expecting the stalled back-door cold front to move
back north as a warm front. There are still some questions as to
how fast this will happen. Currently thinking there is not enough
push to drive it completely through southern New England. As
such...maintained coastal seabreeze fronts along both coasts.
This has big ramifications for temperatures along the East Coast.
Should this front get enough push...current forecast temperatures
are likely 5-10 degrees too low along the immediate coastline. Am
more confident with temperatures farther inland. Should there be
more sunshine that currently thinking...likely too low farther
inland as well.
Thinking there will be more clouds than sunshine today owing to
lots of convective debris from the overnight showers...as well as
new convective clouds as we head into this afternoon.
More showers and thunderstorms are expected later today. There is
the possibility for more isolated severe weather. The greatest
risk should be farther west of our region where the more favorable
combination of instability and shear should be. 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 /12z 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.
Today...expect MVFR-LIFR conditions to gradually improve to VFR
14-16z as SW winds develop. IFR may persist most of the day at
kack. Isolated to scattered convection becoming more widespread
this afternoon...especially west of kmht-korh-kijd.
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.
Winds expected to remain below Small Craft Advisory criteria
through today. Increasing SW flow will result in seas building
over the southern coastal waters. Small Craft Advisory issued for
later today into Thursday for coastal waters where confidence is
highest. Winds should continue to increase tonight into Thursday
as a low pressure moves into the Great Lakes. As such could see
Small Craft Advisory expand into more of the coastal waters around
Cape Cod due to 25 knots wind gusts. Confidence is not yet high
enough to issue advisories for those waters at this time.
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 from noon today to 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...Belk/dunten
short term...Belk
long term...dunten
aviation...Belk/dunten
marine...Belk/dunten
