Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Taunton Massachusetts
932 PM EDT Wednesday may 6 2015

Synopsis...

Dry weather with unseasonably warm afternoons will continue into
this weekend. The potential for wet weather and lower temperatures
may finally arrive early next week.

&&

Near term /until 6 am Thursday morning/...

930 PM update...

Clear skies...diminishing wind and high pressure overhead will
combined with the dry airmass in place. This will allow for a good
night of radiational cooling. Low temperatures will range from the upper
30s to the lower 40s in the normally coolest outlying locations...to
the lower to middle 50s across portions of the higher terrain and
downtown Boston. A touch of brief very localized patchy ground fog
is possible in areas that radiate well near daybreak...but certainly
nothing widespread.

&&

Short term /6 am Thursday morning through Thursday night/...
high pressure remains in place Thursday. With dry air in place...
expecting temperatures to rise rather quickly. A more modest
southerly flow should develop. It is marginal if these winds will
be strong enough to completely preclude sea breeze development.
Odds are there will be a period of a sea breeze along the East
Coast of Massachusetts. Thinking the southerly flow will win out by late in
the day...which should allow maximum temperatures to approach 80
degrees even at the coast.

High pressure moves farther offshore Thursday night. There is a
low probability this could lead to some marine stratus and fog
across portions of the South Coast of Rhode Island and Massachusetts. The main question
will be the availability of low level moisture. At this
juncture...do not have enough confidence to sock in the South
Coast. This will be something which will need to be watched over
the next 24 hours or so.

&&

Long term /Friday through Wednesday/...
*/ highlights...

- Alabama 90 invest yielding some headaches with this forecast
- confident SW-flow and above-average temperatures into the weekend
- S/se-coastal issues overnight-morning with marine stratus / fog
- increasing wet weather chances into early next week

*/ discussion...

A good portion of the forecast hinges upon the evolution of Alabama 90
invest. Wobbling around coastal Carolina prior to slipping NE with
the mean-flow...there is some consensus with regards to track per
forecast guidance but nothing clear about evolution nor timing. Am
though certain that its presence enhances 500 mb ridging across the NE
Continental U.S. Through the weekend. Surface high pressure maintains over the
northwest-Atlantic along the west-periphery SW-flow prevails advecting warm-
moist air north. So looking at a warmer-than-average period of mostly
dry weather. Perhaps a couple of days of 90-degree readings focused
from Friday-Sunday. SW-flow of warm-moist air over the cooler ocean
is likely to yield periods of marine-stratus / fog as moisture pools
beneath the subsidence inversion per the ridge. Could we see some
drizzle? Not out of the question especially for the S/se-coast and
islands.

Chances for wet-weather increase into early next week. A cool front
edges slowly east ahead of which the warm-moist airmass prevails. With
Alabama 90 invest in the mix enhancing the ridging pattern...am expecting
subsidence and dry air to squash any diurnally-forced activity ahead
of the front across our region. Better chances for showery weather
should be along the front where the best moisture-lift-instability
reside. Coincident deep-layer moisture along with precipitable waters in excess of
1.5-inches.

If ridging holds keeping our region dry prior to a prominent trough
signature per ensemble solutions by midweek...then flooding concerns
that were discussed yesterday may not be a worry after all. The mean-
layer flow is still SW around 25 miles per hour with a weak corfidi flow...but
as mentioned earlier...better conditionally unstable/moist adiabatic
environment is north/west putting the Ohio-River valley into north New England
under the risk. Lots of intangibles and low confidence at this time.
Any aspect of the forecast /ridge - cool front - Alabama invest 90/ can
wobble yielding significantly different outcomes.

Yet if consensus of forecast solutions are correct then the trough
sweeping across our region rather quick up against potentially Alabama 90
invest would yield nuisance wet weather activity. Wait and see.

&&

Aviation /02z Thursday through Monday/...
forecaster confidence levels...

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

Short term /today through Thursday night/...

VFR. Sky clear. Light winds overnight into Thursday. Sea-breezes
developing by late morning eroding into evening.

Kbos taf...high confidence in taf.

Kbdl taf...high confidence in taf.

Outlook...Friday though Monday...

VFR. SW-flow. Breezy at times. IFR marine stratus / fog at times
along the S/se-shoreline terminals during overnight-morning periods.
Increasing chances for -shra towards Monday.

&&

Marine...
forecaster confidence levels...

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

Short term /today through Thursday night/...

High confidence. High pressure nearby will keep winds and seas
below Small Craft Advisory thresholds through Thursday night.
Seas generally 1 to 3 feet with good visibility.

Outlook...Friday though Monday...

Winds and seas remaining below Small-Craft Advisory criteria. Expect
breezy SW-flow ahead of an approaching cool front into early next
week ahead of which marine stratus / fog may be an issue along the
S/se-shore-line during the overnight into morning periods. Dry
forecast overall with just a chance of shower activity beginning
Monday.

&&

Fire weather...
dry weather will continue through at least Saturday...if not into
Sunday. Minimum afternoon relative humidity values will drop to
between 15 and 25 percent this afternoon and again Thursday
afternoon. While winds will probably not be strong enough through
the rest of this work week for fire weather headlines...we may
have to be more concerned this weekend if it remains dry.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
Rhode Island...none.
Marine...none.

&&

$$
Synopsis...Belk/sipprell
near term...Frank
short term...Belk
long term...sipprell
aviation...Belk/sipprell
marine...Belk/sipprell
fire weather...staff

National Weather Service Glossary of Abbreviations