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Area forecast discussion 
National Weather Service Taunton Massachusetts
1040 am EST Monday Nov 30 2015

high pressure over eastern New England this afternoon will move
offshore tonight and early Tuesday. Coastal low pressure passing
Cape Cod and a storm coming out of the western USA will bring
periods of rain to New England later Tuesday into Wednesday.
There is a low risk of freezing rain at the onset in northwest
Massachusetts. High pressure then brings dry and seasonable
weather through the weekend.


Near term /until 6 PM this evening/...
1030 am update...

850 mb temperatures are forecast to continue to
warm late this morning and this afternoon which should bring any
lingering ocean effect sprinkles or flurries to an end. Radar
already confirms this trend. A mix of clouds and sun is forecast
for this afternoon. Overcast cloudiness in the CT River Valley was
lifting northward which may lead to increasing sunshine this
afternoon there. Skies were mostly sunny in Rhode Island and interior
portions of eastern Massachusetts and Cape Ann and this trend should
continue. Ocean effect cloudiness will likely continue along the
southeast Massachusetts coast this afternoon. Little change to temperature forecast.
Just a tad cooler to start in CT valley due to cloud cover.


Short term /6 PM this evening through 6 PM Tuesday/...
tonight ...

Greater confidence that it will stay dry. Surface high pressure is
to the east and offshore while the middle- to upper-level ridge is either
across or to the west of New England. Synoptically there is not a lot
of support to suggest that wet-weather will move in by morning. It
is with certainty that top-down moistening will occur as middle- to
high-level clouds increase and thicken...but overall forcing mostly
via isentropic ascent is weak as broader diffluence is absent. Will
see lows drop well below freezing considering the below-average
conditions earlier and an increasing north-component of ageostrophic
flow through the interior. Lows around the middle- to upper-20s.

Tuesday ...

Leaning a WRF/European model (ecmwf) solution holding precipitation off till midday.
This coincident with the consensus of forecast guidance synoptically
building in diffluence aloft with presence of surface high pressure
east. Prior to the ridge remains in place. North-component of ageostrophic
flow persists through the interior keeping temperatures chilly with
just a slight warming ... remaining steady but just above freezing
with precipitation onset. If there is any concern of freezing rain
the focus is across north/west Massachusetts. Meanwhile east-onshore flow
prevails along the coast. Looking at a coastal front setup with
upper-30s for highs across the interior ... low- to middle-40s along
the coast. So wet weather for the most part beginning around midday
and continuing into the evening hours.


Long term /Tuesday night through Sunday/...
big picture...

Closed low west of the Great Lakes moves along the Canadian border
Thursday. A second shortwave races through on Friday. Upper ridge
then builds over the eastern USA for the weekend.

Models show general consistency and so we used a general blend.

The dailies...

Tuesday night-Wednesday...moderate confidence.

Continues to look like a two-phase period of wet weather across
southern New England. Coastal low pressure off New Jersey moves past
cape/Nantucket overnight with one period of wet weather...then a
break Wednesday morning...then more rain in the afternoon/evening as
the system cold front approaches. Small differences in timing of
frontal passage...consensus places it in the Hudson Valley Wednesday evening
and east of mass between 06z and 12z Wednesday.

Southern stream jet extends up the Ohio Valley with broad upper
divergence over New England Tuesday night. The jet curves north into
New York/PA overnight and the venting weakens over our area...but
strengthens again Wednesday afternoon as the jet shifts east over
New England.

With favorable jet dynamics and deep moisture in place...will
continue with high-end likely probability of precipitation. Clouds and an increasing south
flow overnight. There could be some evening cooling but
otherwise expect temperatures to slowly rise most of the night.

Precipitable water values maximize around 1.25 inches Wednesday
afternoon with highest values over cape/islands. This is well above
90 percent exceedance. Good venting and good supply of moisture
should support locally heavy downpours. Possibly some poor
drainage flooding.

Thursday-Friday...high confidence.

Generally dry but with upper low and cold pool concerns. On Thursday
it is the upper low supporting the midweek storm. Cold pool and
associated moisture will generate clouds and widely scattered
showers rain and snow showers across northern mass.

Second shortwave drops south from northern Ontario on Friday. This
one has less associated moisture with the cold core concentrated
farther north. Expect fewer clouds and little/no precipitation.

The mixed layer both days will reach near 925 mb. Temperatures in the layer
will support maximum surface temperatures in the 40s.

Saturday-Sunday...high confidence.

High pressure builds over New England with dry weather.


Aviation /15z Monday through Friday/...
forecaster confidence levels...

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

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

This afternoon... north to NE winds gusting to 15 knots along the coast
should turn to the east and diminish. Winds turning to the southeast by this
evening. -Shra/-shsn still possible along the southeast coast of Massachusetts until
about noon or 1 PM. VFR conditions with broken-overcast conditions around
4000 feet in the CT valley and along the southeast coast...gradually
becoming scattered.

VFR with light wind.

increasing sky cover with cloud heights lowering through the day.
Still some question of timing for onset of MVFR ceilings. Best
estimate would be middle to late afternoon in the CT valley and
evening in the east. Could be a brief period of -fzra in northwest
mass at the start of the precipitation. Increasing east winds along the
South Coast with potential gusts to 25 knots.

Kbos terminal ... VFR. Looks like the -ra on Tuesday will hold
off until Tuesday evening.

Kbdl terminal ... VFR...with overcast 4000 feet through early
afternoon...then becoming scattered. Sky cover increasing again Tuesday
with chance of rain in the early afternoon.

Outlook /Tuesday night through Friday/.....Moderate confidence

Tuesday night-Wednesday...IFR/LIFR especially along the cape and
islands. Conditions may improve to MVFR Wednesday morning but expect
mixed MVFR/IFR later afternoon and evening as a cold front moves
through. Easterly wind Tuesday night becomes west Wednesday
afternoon. Conditions improve to VFR behind the cold front Wednesday

Thursday-Friday...VFR. Northwest gusts to 25 knots on Thursday.


forecaster confidence levels...

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

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

No change to marine forecast late this morning. Winds and seas
relax through today beneath the influence of high pressure
allowing small-craft advisories to conclude. North to NE winds gusting
to 15-20 knots late this morning will turn to the east and diminish this
afternoon. Attention then turns towards Tuesday with the onset of
rain and increasing east-winds with gusts up to 25 kts late in the
day. Subsequently a new round of small craft advisories may be

Outlook /Tuesday night through Friday/...moderate confidence

Tuesday night-Wednesday... coastal low pressure moves across the
waters Tuesday night and off to the northeast Wednesday morning.
Rain and fog will bring areas of poor visibility. Winds will stay
below 25 knots. Seas will build to 5 feet on the southern outer
waters. Cold front moves through late Wednesday or Wednesday night.
Winds become west to northwest behind the cold front. Small Craft
Advisory may be needed.

Thursday-Friday... winds increasing from the northwest with gusts 25-
30 knots. This will build seas to 5-7 feet...mainly on the outer
waters. Small Craft Advisory may be needed Thursday.


Box watches/warnings/advisories...
Rhode Island...none.
Marine...Small Craft Advisory until 1 PM EST this afternoon for anz231-
Small Craft Advisory until 4 PM EST this afternoon for


near term...wtb/sipprell/field
short term...sipprell
long term...wtb

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