Area forecast discussion
National Weather Service Taunton Massachusetts
1031 PM EDT Tuesday Jun 18 2013
Synopsis...
Widespread showers and isolated thunderstorms will gradually
dissipate south and east into Wednesday morning...drying out
thereafter as high pressure builds across the region with more
seasonable conditions into the weekend. Warmer and more humid
weather is expected this weekend as high pressure anchors just south
of New England. Showers and thunderstorms possible Saturday.
&&
Near term /until 6 am Wednesday morning/...
1030 PM update...
Widespread rain should gradually dissipate south and east as the
main disturbance /inferred from water vapor imagery over Lake
Ontario and upstate New York/ rotates around the low centered over
Quebec and through New England. Subsidence and drier air should
dominate the regions weather by morning.
Of considerable note is the line of showers re-emerging along a
line from coastal New Hampshire back into the lower Hudson Valley
of New York. This is likely the 850 mb front located above the inversion
per 0z Chatham sounding. Available moisture transport within the
low-levels is likely lifting along the front in a region of
steeper lapse rates /cold pool evident at the middle-levels from the
inversion to around h6 per 0z Chatham sounding/. Low confidence
for any thunder...and feel what GOES up will quickly go down. Any
cells should not sustain for long.
Feel the flooding threat has dissipated and the Flood Watch has
been allowed to expire accordingly. Weather forecast grids have
are amended accordingly. Worst of the weather for the next several
hours will be across the South Coast...especially the cape and
islands.
A secondary concern is for patchy dense fog. As conditions improve
north to south with weak winds and potential clearing...the
expected cooling coupled with antecedant rains from earlier today
making a more moist boundary layer profile moreso than high-res
models can infer will yield fog especially in Interior Valley
locations.
&&
Short term /6 am Wednesday morning through Wednesday night/...
Wednesday...
Cooler airmass building south should allow significant boundary
layer mixing of around 4-6 kft. Subsequently...anticipating the mix-
down of faster momentum and drier air. Not looking at any fire
weather headlines with recent rains. Dewpoints down to around 50
degrees...some gusty northerly winds mainly across eastern New
England. Expecting diurnal scattered to broken fair-weather cumulus
across interior New England.
&&
Long term /Thursday through Tuesday/...
Highlights...
* high pressure will lead to quiet weather Thursday and Friday
* high pressure S of southern New England brings warm...humid conditions this weekend
* showers and thunderstorms possible Saturday
There is good general agreement amongst the models through much of
the long term. There are some model discrepancies regarding the
strength and extent of an upper level ridge over the eastern U.S.
Through this weekend. Ultimately this will affect the weather in
this area mainly in where and when showers and thunderstorms are
able to develop. The consensus is with the European model (ecmwf) and the upper
level ridge over the southeast Continental U.S. Thursday and gradually building
northward into the Ohio Valley by Saturday and into the NE Continental U.S.
Sunday and sinking back south early next week. Otherwise...am
expecting fairly quiet weather with more Summer like temperatures
and a few humid days thrown in there as well. With thunderstorms
currently moving over southern New England...will make whatever
changes are necessary and base much of the forecast off the
previous forecast.
Thursday and Friday...high pressure crests over southern New England
with a warming trend in temperatures.
Saturday...best chance for showers and thunderstorms as warm...moist
air builds into the region on SW winds. We will still be on the
periphery of the ridge with decent instability noted in steep middle
level lapse rates.
Sunday through Tuesday...high pressure moves offshore as the upper ridge
sinks S slowly. Warm...moist air remains in the region on
southwesterly winds...and increases instability. However...not much
of a trigger any of those days and models are not showing much...if
any...quantitative precipitation forecast so will keep thunderstorm chances low.
&&
Aviation /02z Wednesday through Sunday/...
Forecaster confidence levels...
Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.
Near term /through Wednesday night/...
Moderate confidence for trends...lower confidence for timing
through tonight...then moderate confidence Wednesday-Wednesday night.
Tonight...expect conditions to improve to mainly VFR across north
Massachusetts/S New Hampshire...patchy MVFR-IFR ceilings/visibilities mainly in the valleys with
patchy fog. Across central and southern areas...MVFR-IFR
ceilings/visibilities in low clouds/showers. May see scattered thunderstorms through
midnight. Brief LIFR conditions possible.
Wednesday...MVFR-IFR ceilings/visibilities to start mainly S of the Mass
Pike...then improving to VFR during the morning. MVFR visibilities may
linger along S coast into the afternoon.
Wednesday night...VFR.
Kbos terminal...moderate confidence. Low confidence in another
shower moving over the terminal between 00 and 02z.
Kbdl terminal...moderate confidence. Rain showers possible through 01z.
Outlook...Thursday through Sunday...
Thursday and Friday...high confidence. VFR.
Saturday...moderate confidence. Mainly VFR. Low probability of
showers and thunderstorms briefly lowering conditions to MVFR/IFR.
Sunday...moderate to high confidence. VFR.
&&
Marine...
Forecaster confidence levels...
Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.
Near term /through Wednesday night/...moderate confidence.
Tonight...winds shift to NE as cold front moves offshore...then
low pressure passes S of the waters. NE winds increase...gusting to 25
knots toward daybreak across the southern outer waters and east of Cape
Cod with seas up to 5 feet. Low probability of thunderstorms this evening.
Wednesday...NE winds gusting to 25 knots through midday on the outer
waters from Cape Cod southward. May also see gusts up to 25 knots on
Nantucket Sound and Buzzards Bay mainly during the morning...so
have put up small crafts there. Seas up to 5 feet...but should
subside by evening.
Wednesday night...winds and seas below small craft criteria.
Outlook...Thursday through Sunday...
High confidence.
Quiet boating weather expected through Sunday with high pressure
near or over the waters. The only exception is Saturday when
showers and thunderstorms may limit visibilities on the waters.
&&
Hydrology...
Have kept Flash Flood Watch up through this evening across the
region...though may end it early across lower CT valley region.
Have had several reports of flash flooding due to torrential rains
from thunderstorms as the cold front slowly moves through. Have also
received a couple of reports of small streams overflowing their
banks.
As for river flooding...the Charles at Dover remains just above
flood stage. Latest guidance indicates that this river will only
slowly fall and remain in minor flood through late Wednesday night.
&&
Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
New Hampshire...none.
Rhode Island...none.
Marine...Small Craft Advisory from 6 am to noon EDT Wednesday for
anz232-234.
Small Craft Advisory from 4 am to 6 PM EDT Wednesday for
anz254>256.
&&
$$
Synopsis...rlg/evt
near term...sipprell
short term...evt
long term...rlg
aviation...rlg/evt
marine...rlg/evt
hydrology...weather forecast office staff
