Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

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

Synopsis...
dry weather with unseasonably warm afternoon/S will continue into
this weekend. The potential for wet weather and lower temperatures
may finally arrive late Sunday into early next week.

&&

Near term /through tonight/...
215 PM update...

Light/variable or calm winds in place. As expected...sea breezes
have developed along most of the southern New England coast.
Tweaked near-term conditions to reflect the observed trends.

High pressure overhead and mainly clear skies should lead to a
good night of radiational cooling. That said..still expecting
seasonable minimum temperatures.

&&

Short term /Thursday 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 Tuesday/...
highlights...

* SW flow will bring mild to warm temperatures through this
weekend for most areas
* low clouds and fog each overnight/morning with onshore winds
* increasing chance for showers from late Sunday into early next
week

Discussion and model preferences...

Continued 500 mb long wave blocking pattern remains in place for most
if not the entire long term forecast period with eastern U.S.
Ridging and blocking cutoff low pressure/trough across the west. May
start to see pattern breaking down...though some timing
differences amongst the operational models from late Sunday
through early next week lowered confidence during this timeframe.

Expect dry conditions to continue Friday through Sat as high pressure
ridge builds slowly east...allowing winds to shift to S-SW. Mild to
warm temperatures will continue through Sunday as dewpoints slowly but
steadily rise with the deep onshore flow. Temperatures along the S coast
will be cooler with the onshore winds as well. Will also see
development of low clouds and patchy fog each late night to middle
morning period along the coast and...as dewpoints increase...across
susceptible inland areas by this weekend.

May start to see a very slow moving front out of southern Quebec
and northern New England bring a few showers later Sunday into
Sunday night mainly across north Massachusetts around the Route 2 area. Some more
instability also looks to work in...so can not rule out a rumble
of thunder or two but tough to determine placement so left out
mention for now. Noting the 00z GFS op run trying to break down
the upper ridge and therefore moving the front faster toward the
region than the 00z GFS/ECMWF. Another factor is the developing
coastal low off the middle Atlantic/southeast U.S. Coast that may take on
subtropical characteristics. All op models appear to stall this
feature...which in turn should also help keep the upper ridge in
place and slow the progression of the front.

Models and ensembles showing progression of the cutoff low out of
The Rockies and plains states toward the Great Lakes by Monday night
into Tuesday...with associated low pressure/cold front that tries to push
the ridge and coastal low offshore. This appears to be the best
chance for showers along with better shot for convection but
again timing is the issue. Noted potential for periodic heavy
rainfall that may tend to train across the region as the front
slowly crosses as mentioned by previous forecaster...but too
early to tell how much at this point. Rather low confidence during
this timeframe.

Went with a blend of the available guidance into this weekend...
then transitioned to a blend of ensemble guidance from late Sunday
Onward which appeared to give better resolution of the timing
differences as slow moving front starts to sag toward the region.

&&

Aviation /18z Wednesday 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/...

High confidence. VFR conditions. Sea breezes diminish this
evening. Local sea breezes develop again toward midday Thursday.

Kbos taf...high confidence in taf. Southeast sea breeze gradually
breaks down early this evening. Moderate probability a southeast
sea breeze redevelops middle morning Thursday.

Low probability for IFR conditions toward the South Coast late
Thursday night.

Kbdl taf...high confidence in taf.

Outlook...Friday through Sunday...moderate confidence.

VFR. Expect S-SW winds. May see periods of IFR conditions in fog
and low clouds mainly along the S/southeast shoreline terminals during
overnight into the morning periods each day. Increasing chances
for -shra Sunday.

&&

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 through Sunday...moderate confidence.

Expect winds and seas to remain below small craft criteria through
the period. S-SW winds may gust up to 20 knots at times mainly across
the outer waters. Visibilities will be reduced each overnight into
early morning hours in low clouds and fog.

&&

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/evt
near term...Belk
short term...Belk
long term...evt
aviation...Belk/evt
marine...Belk/evt
fire weather...staff

National Weather Service Glossary of Abbreviations