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Area forecast discussion 
National Weather Service Taunton Massachusetts
951 am EDT Thursday Oct 2 2014

Synopsis...

Cool...damp weather continues through the early part of the day with
a drying trend expected through Friday. A cold front approaches on
Saturday...crossing western New England in the late afternoon /
evening and eastern sections at night. High pressure brings cooler
temperatures Sunday followed by a warming trend early next week.
Another front moves across late Tuesday and early Wednesday.

&&

Near term /until 6 PM this evening/...

10 am update...

Trowaling evident with water-vapor imagery beginning to show signs
of collapse in radar-echo returns. Feel this is subsequent of the
upper-level low transitioning southeast along with the rrq of the upper-
level jet...as better convection in the northwest-flank of the surface-850 mb
low usurps moisture trowaling back west. Also impacts associated with
a ridge of high pressure and drier air building east. Already seeing
the west-flank of moisture within the water-vapor eroding.

Showers expected to dissipate towards midday towards the southeast. May
see some activity linger along the east/NE-slopes of higher terrain
with persistent easterly onshore moist-flow perhaps undergoing
some weak orographic lift. Anticipating improvement late with all
activity concluding and conditions beginning to clear.

Looking at a cloudy and dreary day with the best chances of seeing
some sunshine towads the northwest late in the day. Breezy NE-flow the
strongest of which will be along the east-facing slopes. This will
keep east/southeast portions of New England in the upper-50s for highs.
Low-60s elsewhere with the anticipated warmest spots in the CT-
River Valley with readings around the mid-60s.

&&

Short term /6 PM this evening through 6 PM Friday/...

Tonight...

Clearing continues as a weak upper level ridge builds in. Light
northerly winds...high pressure...and mostly clear skies will
result in cooler temperatures overnight with lows in the 40s
expected for most locations away from the coast and urban centers.

Friday...

Southern New England will find itself in the quiet between two
weather systems. The departing coastal low pressure southeast of
Nantucket and a deep upper level trough moving into the Great
Lakes. Weak upper ridging over southern New England will provide
quiet...somewhat more seasonable weather for southern New England.

&&

Long term /Friday night through Wednesday/...

Big picture...

Trough migrating to the Great Lakes this weekend becomes a closed
low and sits in that position through early next week as a couple
of shortwaves rotate through the flow...one Saturday night/Sunday
and the second Tuesday night/Wednesday. The upper low then slowly
migrates north through northern Ontario and Hudson Bay midweek.
The flow across the northern USA then becomes zonal Thursday.

Contour heights within the closed low will be well below normal...
suggesting cold temperatures under the core. But that will be in
the Great Lakes. Here in New England heights initially drop behind
the first shortwave early Sunday which should bring colder air to
New England. But the low remains to our west while an upper ridge
builds over the west Atlantic. Heights rebuild over the East Coast
with values returning to near normal during the first half of next
week.

The dailies...

Friday night...

High pressure to our north with an east flow at low levels.
Meanwhile low pressure which departed New England will linger
south of Nova Scotia and feed cloud-level moisture into that east
flow. Model cross sections show increasing and deepening moisture
below 850 mb Friday night. Expect increasing low clouds and fog.
Could be some drizzle especially near the mass East Coast. Min
temperatures should be near dew point...in the upper 40s to middle 50s.

Saturday...

Upper low over the Great Lakes with southwest to south flow aloft
over the northeast USA. Cold front in central New York and eastern
PA will be pushed northeast by this flow. As the front lines up
with the upper flow...the push will diminish and so the front will
slow down. This will make timing of the front and the associated
showers a challenge. Model consensus would bring the cold front to
the Hudson Valley 18z and to the CT valley around 00z...then to
the Massachusetts East Coast by 06z. So the best chance of showers
will be roughly noon to midnight and possibly a couple of hours
later. We have aimed highest probability of precipitation during this period. Precipitable
water values are forecast around 1.5 to 1.7 inches. The upper end
of this range would be 2 Standard dev above normal...suggesting some
locally heavy downpours especially along the South Coast.

After the front GOES through...cooler air moves in from the west
Saturday night. Min temperatures should be several degrees cooler than
Friday night.

Sunday-Monday...

Upper shortwave overhead Sunday morning lifts north by afternoon.
High pressure builds north from the southern states. Expect a
clearing trend Sunday but with west winds bringing ing cooler air.
The mixed layer will reach to at least 850 mb and possibly a
little higher. This would mix temperatures of 1-3c to the surface and
support maximum surface temperatures in the low to middle 60s...could be upper 50s
in the hills. Temperatures aloft warm about 4c Monday so maximum surface temperatures
should also be a little warmer...we went with middle to upper 60s.
Nighttime temperatures should be coldest Sunday night...the model range
of upper 30s to around 50 looked reasonable.

Tuesday-Wednesday...

Another shortwave rotating around the Great Lakes low will swing
a weak cold front across the northeast USA Tuesday...mostly during
the afternoon and night. The front then moves offshore Wednesday
morning. This will support a chance of showers shortly before and
during passage. High pressure then builds with clearing skies late
Wednesday and Wednesday night.

&&

Aviation /14z 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 Friday...moderate confidence.

Today...high confidence in trends...lower confidence in timing.

IFR ceilings/MVFR visibilities in rain and fog from the Worcester Hills
east...MVFR ceilings and patchy MVFR visibilities in the CT valley and
east slopes of the Berkshires. Expect these conditions to improve
from west to east very slowly as rain comes to an end. Should see
VFR conditions most locations by the end of the day with the
possible exception of the cape and islands where MVFR conditions
may linger. Northeasterly winds gust to 25 kts on the cape and
islands.

Tonight...high confidence. Mainly VFR. Low probability of patchy
fog in normally prone locations.

Friday...high confidence. Mainly VFR.

Kbos...high confidence in trends...lower confidence in timing.

Kbdl...high confidence in trends...lower confidence in timing.

Outlook...Friday night through Monday...moderate confidence.

Friday night...

Increasing clouds from the Gulf of Maine moving west. Ceilings lower
to IFR with patches of LIFR in fog/drizzle.

Saturday...

IFR/LIFR in low clouds/fog/drizzle in the morning...especially in
eastern Massachusetts. A cold front then approaches from the west
with MVFR and areas of IFR in showers and fog during the afternoon/
evening in the CT valley and Worcester Hills. Showers and fog move
across Rhode Island/eastern mass/Merrimack valley New Hampshire during the late
afternoon and early night. Increasing south winds with 40 knots
possible at 2000 feet. This could cause some low level turbulence
during the afternoon and evening.

Saturday night...

The cold front moves offshore around midnight. Winds shift west
and drier air moves in. Expect conditions improving to VFR with
patches of lingering MVFR ceilings overnight.

Sunday-Monday...

VFR with gusty west winds. High pressure builds over the region
with fair weather.

&&

Marine...

Forecaster confidence levels...

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

Short term...today through Friday...high confidence

Persistent northeasterly winds increase through the day gusting
up to 25 to 30 kts this afternoon. Because of the northeasterly
winds...seas will remain in the 5 to 10 foot range on the outer
waters. Small craft advisories continue through the period for all
the waters.

Outlook...Friday night through Monday...moderate confidence.

Friday night...

Low clouds and fog move in on east winds and remain over the
waters through the night. Expect poor visibilities in fog and drizzle.
Diminishing 5 to 8 foot seas on the outer and northeast- exposed
waters may require a continued Small Craft Advisory.

Saturday...

Lingering poor visibilities during the morning in fog and drizzle.
Conditions may improve during the afternoon as winds pick up out
of the south and as showers move in ahead of a cold front. The
cold front will cross the waters around midnight...followed by a
wind shift. West winds will then bring drier air overnight. South
winds ahead of the front may reach 25 to 30 knots at times. West
winds behind the front may also reach 25 to 30 knots at times.
Seas 5 to 7 feet on the outer and exposed waters. Small Craft
Advisory may be needed.

Sunday-Monday...

High pressure builds over the waters Sunday and then shifts
toward sea Monday. West winds Sunday may gust near 25 knots and
seas may linger around 5 feet. A Small Craft Advisory may still be
needed. Conditions get quieter Monday with winds and seas below
small craft levels.

&&

Box watches/warnings/advisories...

CT...none.
Massachusetts...none.
New Hampshire...none.
Rhode Island...none.
Marine...Small Craft Advisory until 11 am EDT Friday for anz232.
Small Craft Advisory until 11 PM EDT this evening for anz233-
234.
Small Craft Advisory until 2 am EDT Friday for anz230.
Small Craft Advisory until 4 am EDT Friday for anz231.
Small Craft Advisory until 8 PM EDT this evening for anz236.
Small Craft Advisory until 6 PM EDT Friday for anz235-237.
Small Craft Advisory until 8 PM EDT Friday for anz250-251-
254>256.

&&

$$

Synopsis...wtb/rlg
near term...wtb/rlg/sipprell
short term...rlg
long term...wtb
aviation...wtb/rlg
marine...wtb/rlg

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