Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Taunton Massachusetts
723 am EDT sun may 24 2015


Southwest winds will bring warmer air into southern New England
beginning today. Warm and muggy conditions build into midweek
ahead of increasing chances of showers and thunderstorms. Could
remain wet all the way through into next weekend.


Near term /until 7 PM this evening/...

730 am major changes to the forecast.

Middle level clouds drifting across north New England in advance of weak
short wave diving southeast from Canada. They may graze north Massachusetts.

Otherwise plenty of sunshine expected today as cross sections show
dry air through column. Mixing layer will deepen significantly
once again in response to daytime heating...with 25-30 miles per hour gusts
expected near the S coast...Cape Cod and islands as well as in
eastern Massachusetts with 20-25 miles per hour gusts elsewhere. Winds will diminish
toward evening as boundary layer begins to stabilize...aside from
S coast where it will take a bit longer.

Highs will top out in 70s and lower 80s except 60s on S coast...
Cape Cod and islands due to SW flow off colder ocean.


Short term /7 PM this evening through 6 PM Monday/...

SW flow persists tonight and Monday as models bring warm front
through upstate New York and northern New England...which should be
focus for any showers or storms. 00z GFS seems overdone in
bringing precipitation this far east...especially given rising 500 mb
heights and lack of deep moisture or appreciable lift over our
area. As a result we do expect to see an increase in cloudiness
/mainly middle level/ with perhaps an isolated shower or storm Monday
across northwest Massachusetts.

Lows will drop back into 50s tonight and once again climb into
70s/lower 80s Monday except 60s on S coast...Cape Cod and islands.


Long term /Monday night through Saturday/...

*/ highlights...

- warm muggy and dry Tuesday into Tuesday night
- increasing shower / thunderstorm potential Wednesday - Thursday
- perhaps a lull in the weather on Friday
- looking potentially wet and active for next weekend

*/ discussion...

Forecast guidance struggling with both strength and influence of
ridging across the east-Continental U.S. And subsequent allowance of north-stream
energy to slip S. As been the trend the last several days...the
ridge deamplifies subsequent to the flattening maritime flow and
retrograding low pulling cooler air cyclonically SW. There is not
much support in maintaining a ridging pattern. So expectation through
the week is for north-stream energy to have the ability to trough S
shifting the convergent SW-flow along with Theta-E / instability
axes into New England. Anticipating increasing chances for showers
and thunderstorms especially across the interior. Shear not impressive
compared to echo prior forecaster with concern of
heavy rain as a threat.

Will keep Tuesday into Tuesday night dry. Though the warm and muggy
conditions potentially exceeding convective-temperatures across the
north and west may yield thunderstorms that would push east with the steering
flow...feel dry air and subsidence will erode / weaken any activity
into New England. The better forcing and SW-convergent flow of moist-
instability axes is well northwest at this time. Low-90s possible across
interior valleys. Expect marine stratus / fog along the S/se-coast
perhaps developing as early as Monday night into Tuesday.

Wednesday into Thursday the ridge weakens allowing the favorable
environment for showers and thunderstorms to shift southeast. Increasing
pop chances accordingly. Some question as to how effectively we can
destabilize. Could be issues with cloud cover should activity on
Wednesday expected mainly west drifts east overnight into Thursday. Will
continue with warm and muggy conditions. Low-90s possible across
interior valleys especially Wednesday. Continued potential of marine
stratus / fog along the S/se-coast.

Friday could be a lull with dry air and high pressure in place if
you believe the GFS over the European model (ecmwf). Low confidence. Consensus of
forecast guidance has another wave north pushing a frontal boundary S
and stalling over New England making it a focus for a prolonged
period of wet-weather. Have some doubts with convergent mass-fields
north as surface reflections focus S with thermal-instability-moist
axes. Should have a better idea as we get closer in time.


Aviation /12z Sunday through Thursday/...

Forecaster confidence levels...

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

Short term /through Monday/...high confidence.

12z update...

VFR with SW flow. 20-25 knots gusts later this morning into early
evening...especially near coast. Ceilings at or above 060 late tonight and
Monday with an isolated -shra/thunderstorms and rain possible across northwest Massachusetts.

Kbos terminal...high confidence in taf.

Kbdl terminal...high confidence in taf.

Outlook...Monday night through Thursday night...

Monday night into Tuesday night...moderate confidence. VFR. Breezy
SW-flow with 20-25 knots gusts. IFR stratus / fog possible across the

Wednesday into Thursday night...moderate confidence. Increasing
chances for -shra / thunderstorms and rain. Tempo MVFR-IFR with any activity. SW-flow
with 20 knots gusts at times. IFR stratus / fog remains possible across
the S/se-coast.



Forecaster confidence levels...

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

Short term /through Monday/...high confidence.

730 am update...Small Craft Advisory for all waters today.

Still seeing around 20 knots gusts on S coastal bays / sounds per
coastal buoys and mesonet observations this morning...where Small Craft Advisory
remains posted. Expanded Small Craft Advisory to include all waters with expected
25 knots gusts beginning this morning and into this evening...especially
within few miles of shore. Seas will build to 5 feet on outer
waters...where Small Craft Advisory remains in effect through midnight when seas
should subside.

Increasing SW winds against departing tide on Buzzards Bay and
western portion of Vineyard Sound should lead to steep waves...
first through sunrise and again this afternoon.

Gusts may be marginal along east Massachusetts coast including bos Harbor but
decided to include these areas due to increase in Holiday
recreational traffic.

Winds and seas diminish tonight. SW flow persists Monday but gusts
are expected to remain below Small Craft Advisory.

Outlook...Monday night through Thursday night...

Moderate confidence. Persistent SW-fetch with gusts around 20-25 kts
at times. Wave heights in excess of 5-feet mostly on the outer
waters but getting into the S inner sounds. Fog anticipated lending
to visibility restrictions.


Fire weather...

Still have concern for elevated fire weather spread today given
low humidity /20-30 percent/...gusty SW winds /20-25 miles per hour/ and lack
of significant rainfall over past several weeks. We will issue
Special Weather Statement to address this concern.

Persistent SW flow will bring gradual increase in humidity this


Box watches/warnings/advisories...

Rhode Island...none.
Marine...Small Craft Advisory until 7 PM EDT this evening for
Small Craft Advisory until 7 PM EDT this evening for anz230-
Small Craft Advisory until midnight EDT tonight for anz254>256.



near term...sipprell/jwd
short term...jwd
long term...sipprell
fire forecast office box staff

National Weather Service Glossary of Abbreviations