Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Taunton Massachusetts
1100 PM EDT Sat Apr 19 2014

Synopsis...
high pressure in control will result dry weather into Tuesday. Mild
afternoon/S except for chilly sea breezes along the coast Sunday.
A low pressure and an associated cold front will likely bring a
period of wet weather Tuesday afternoon into Wednesday. Another
high pressure arrives with more dry...pleasant conditions for late
next week.

&&

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

1040 PM update...
while strong high pressure ridge continues to build S out of Quebec
this evening...noting an area of high clouds that has worked north
from the strong storm system off the Georgia/SC coast. Models not
handling this well at all. Big question will be whether enough dry
air works S as the high continues to build in. This could also
affect radiational cooling and temperature drop overnight. Also see area
of clouds working out of central Canada and the central Great
Lakes as short wave works north of the region...which could also keep
high level moisture moving in.

Have slowed the temperature drop over the next few hours...but kept
current temperature trends after 06z...for now. Will monitor closely for
any changes to current thinking.

Have updated remaining grids to bring conditions current.

&&

Short term /6 am Sunday morning through Sunday night/...
high pressure over eastern Canada will shift to a position just
south of the Maritimes late Sunday night. This will result in
mostly clear skies...but also onshore winds. Since the water is
still rather cold...temperatures along the immediate coast should
hold in the 45-50 degree range. Elsewhere...plenty of sunshine
should boost maximum temperatures well into the 50s. A few locations
near the CT and Merrimack River valleys may reach around 60
degrees.

Winds will be much lighter than today...so it will be a pleasant
afternoon inland from the coast. Not as ideal radiational cooling
conditions Sunday night...so expecting seasonable temperatures.

&&

Long term /Monday through Saturday/...
model overview...
split flow dominates the beginning of the coming week with mainly
zonal flow. Towards the end of the week...the flow becomes phased on
the back side of a wave moving through the region midweek. This
becomes negatively tilted...but should do so just off the East
Coast. Disagreement occurs around the time the phased flow comes in
as to how fast the wave moves through. Usual model biases...ensemble
guidance and the wpc solution guide this forecast as to the speed of
the passage. Another wave arrives during the early weekend.

Dailies...

Monday to Tuesday...high dominating the northeast USA for the past
few days slowly meanders to the east. Return flow on the back of the
high allows the airmass to get milder. Both days see 850mb temperatures
around 8-10c and model mixing up to around 900mb so could see it
approach 70f especially since mixing may be underdone. Monday...with
its weak winds of less than 10kts and warmer temperatures on land...may see
a weak sea breeze develop. A cold front approaches the region
Tuesday night with moist columns...precipitable waters 1sd above normal and k-
index approaching 30. With the aforementioned convective parameters
and total of totals nearing 50 can/T rule out the possibility of
thunder. Precipitation should amount to around 0.25". Low level jet at 850 mb
approaching 30kts so some gusty winds in the middle to upper 20s should
be seen.

Wednesday and Thursday...cold frontal passage occurs early in the
morning. Negatively anomalous trough follows it indicating cold air
1sd below normal to follow the front for Thursday. However...rising
heights from midlevel ridge over the eastern half of the country
should keep temperatures from falling too much. Gusty winds should be seen
due to a low level jet from the northwest and from the phased winds mixing
down.

Friday...with high pressure moving east from the southeastern states
have kept the region dry and slightly above average with the high
pressure/S return flow.

Saturday...a bit of a model discrepancy as to when the low pressure
should make its way into the region...but have gone with chance probability of precipitation
to cover the area. Also looks to be some convective nature to this
storm.

&&

Aviation /03z Sunday through Thursday/...
low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.

Short term...today through Sunday night...high confidence.

VFR conditions. Winds become onshore Sunday morning...then
continue to shift southeast Sunday afternoon...then south Sunday
night.

Kbos terminal...high confidence in taf.

Kbdl terminal...high confidence in taf.

Outlook...Monday through Thursday...

Monday into Tuesday...high confidence. Mainly VFR. Mainly southwest
winds.

Tuesday night into Wednesday... moderate confidence...periods of
MVFR/IFR in low ceilings and visibilities due to rain. Conditions looks to
improve on Wednesday behind the front. West/northwest wind gusts to around 30
kts possible.

Thursday... VFR conditions on clear skies and northwest winds around 15
kts. Gusts to around 35 kts over the waters to the north.

&&

Marine...
forecaster confidence levels...

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

Short term /today through Sunday/...high confidence.

Tonight...

Looks like we may see a period of north to northeast 25 knot wind
gusts over the eastern waters in a surge of cold advection. Kept
the eastern Atlantic waters with Small Craft Advisory headlines.
Its possible we may need to extend them into Cape Cod Bay and
Nantucket Sound for a time.

Sunday and Sunday night...

Winds should remain below advisory thresholds across most of the
waters. However...marginal 5 foot seas expected to linger into
the late morning/early afternoon across portions of the eastern
Atlantic waters before finally subsiding.

Outlook...Monday through Thursday...

Monday into Tuesday...high confidence. High pressure dominates the
weather for this period with few S/SW gusts around 25kts possible.

Tuesday night into Wednesday...moderate confidence. Cold front moves through
the region from west to east bringing periods of rain. Waves should
remain below 5ft. Winds should remain below 15 kts for this period.
Rain should end at about late morning to midday.

Thursday...potential northwest winds gusting to 35 knots. Expect seas to build
to 5-8 feet during this time. Will monitor for potential gale
conditions.

&&

Fire weather...
Sunday...although the dry weather continues...winds will be much
lighter and high temperatures a bit lower. No headlines planned.

&&

Hydrology...
minor flooding continues along portions of the mainstem CT river.
All points have finally crested and are now receding. See the
latest flood statement for details.

Flood warnings remain posted along CT river at...

Hartford and Middle Haddam

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
New Hampshire...none.
Rhode Island...none.
Marine...Small Craft Advisory until noon EDT Sunday for anz250-255.
Small Craft Advisory until 5 PM EDT Sunday for anz254.

&&

$$
Synopsis...Belk/99
near term...evt
short term...Belk
long term...wtb/hr
aviation...wtb/Belk/hr
marine...Belk/evt/hr
fire weather...staff
hydrology...staff