Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Taunton Massachusetts
1005 PM EDT Friday Oct 24 2014

Synopsis...
low pressure will move into the Maritimes tonight. A weak ridge
of high pressure provides dry and seasonably mild weather
Saturday. A cold front will sweep across the region Saturday night
and may be accompanied by a few showers...then dry and blustery
weather follows for Sunday with warming early next week. A cold
front may bring showers Tuesday night into Wednesday. High
pressure briefly visits on Thursday with the potential for a low
pressure system in our vicinity at the end of the next workweek.

&&

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

10 PM update...

Back edge of cloud line moving across the CT River Valley and advancing
steadily eastward. Clouds will continue to erode as middle level flow
transitions from cyclonic to anticyclonic in response to weak
short wave ridging approaching from New York and PA.

Seasonably cool night ahead with temperatures falling into the
40s...upper 30s well inland. A modest northwest wind at 5 to 15 miles per hour with
gusts up to 20 miles per hour higher terrain and along the coast will make it
feel a bit cooler. Previous forecast captures these details nicely
so only change with this forecast update was to modify hourly
grids to better reflect current trends per satellite imagery and
surface observation.

&&

Short term /6 am Saturday morning through Saturday night/...
Saturday...
fairly potent middle level shortwave and associated cold front will be
moving east from the upper lakes. Weak shortwave ridging ahead of
the trough will provide enough subsidence in southern New England for mosunny skies
for much of the day along with a modest westerly breeze.
Soundings show mixing up to 925 mb. Temperatures at this level are near
10c which translates to maxes 60-65 degrees...cooler higher
terrain.

Saturday night...
middle level shortwave moves across southern New England with cold front moving into
west zones 00-02z and off the coast around 06z. Moisture and low
level convergence are limited but shortwave is fairly robust and
there is enough qg forcing to support a few showers. We have 20-30
probability of precipitation in the grids. Begin the front...W/NW winds will become gusty
overnight.

&&

Long term /Sunday through Friday/...
* mainly dry and slightly cooler than normal on Sunday
* high pressure prevails on Monday
* chance for showers Tuesday night/Wednesday with a cold frontal passage
* potential for low pressure system in our vicinity at the end of
next week

Details...

Sun...at the surface a low pressure system will cross through the
Canadian Maritimes during the day...with its associated cold front
pulling further offshore from southern New England. Fairly tight
pressure gradient over our area with some cold air advection and
h850 winds 30 to 40 knots...so will likely have a blustery northwest wind on
sun with gusts 20 to 30 miles per hour at times possible. Aloft...models
continue to show robust short wave digging into upper trough and
moving through our area. This will mainly bring clouds to our
area...and possibly isolated showers in far western Massachusetts/SW New Hampshire. High
temperatures a few degrees below normal...mainly in the 50s.

Monday and Tuesday... high pressure will slide across the region from the
SW on Monday...with abundant sunshine. A warm front will cross the
Great Lakes region on Monday...then track through and north of our
area on Tuesday. While an increase in clouds is expected with the
warm front...the better chance for showers looks to be minimal.
Mainly dry conditions are anticipated in our area on Tuesday.
Temperatures are expected to moderate...with highs in the 60s across
many locales.

Tuesday night and Wednesday... surface cold front will be sliding across the
region during this timeframe as low pressure moves through Quebec. Precipitable waters
close to the cold front approach 1.5 inches. Enough instability
available for showers in the vicinity of the front but not enough
for thunder at this point. H850 winds 30 to 40 knots so some gusty
winds with the showers still possible.

Thursday and Friday... continue to expect brief ridging on Thursday behind
the frontal passage. However model discrepancies exist on the
development and track of a potential low pressure system. The brief
high pressure may give way to a coastal low pressure system at the end
of the workweek...depending in part on whether or not the upper
level trough becomes a cutoff low. Have slight chance to chance probability of precipitation
for Thursday night and on.

&&

Aviation /02z Saturday through Wednesday/...
forecaster confidence levels...

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

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

10 PM update...

No major changes from 00z tafs. Earlier discussion below.

----------------------------------------------------------------

Tonight...MVFR ceilings lifting to VFR 00z-03z with the exception of
Cape Cod and the islands...where MVFR ceilings should lift to VFR
between 04z and 07z. Gradual decrease in cloud cover. After 07z
VFR with clearing skies.

Saturday...VFR.

Saturday night...VFR ceilings. A few showers possible with brief MVFR
conditions.

Kbos...high confidence overall. Ceilings should rise from MVFR to VFR
by 02-03z.

Kbdl...high confidence.

Outlook...Sunday through Tuesday...

High confidence. Mainly VFR. Scattered showers Tuesday night/Wednesday
may bring localized MVFR conditions.

&&

Marine...
forecaster confidence levels...

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

Short term /through Saturday night/...

10 PM update...

Increased winds slightly from previous forecast along with seas a
bit higher. Otherwise previous forecast on track. Earlier
discussion below.

--------------------------------------------------------------------

Tonight...winds have diminished below Small Craft Advisory thresholds but seas
remain above 5 feet over the eastern waters so Small Craft Advisory will continue.
Seas should subside below 5 feet toward daybreak.

Saturday...northwest winds in the morning become west/SW in the afternoon as
cold front approaches from the west. Wind gusts to 20 knots likely
during the afternoon. Seas below Small Craft Advisory.

Saturday night...expect increasing west winds through the night
as cold front moves across the waters. Good Post frontal mixing
supports wind gusts to 30 knots with building seas...especially over
south coastal waters. Small craft advisories will be needed.

Outlook...Sunday through Tuesday...

Sunday and Sunday night...high confidence in at least Small Craft
Advisory conditions. Northwest winds with gusts of 20 to 30 kts expected
behind a cold front that will be moving offshore Sunday morning.
Seas 5-8 feet. Low chance for a period of gale force gusts late sun or
Sun night.

Monday...moderate confidence...Small Craft Advisory seas expected to linger over the
course of the day but gradually subside. Winds gradually diminish as
well as high pressure builds over the waters.

Tuesday...moderate confidence...winds and seas below Small Craft Advisory threshold
as high pressure is still over the region.

Wednesday...low confidence on timing. Cold front approaches and
crosses through the waters. Small Craft Advisory winds/seas possible.

&&

Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
New Hampshire...none.
Rhode Island...none.
Marine...Small Craft Advisory until 8 am EDT Saturday for anz250-254.
Small Craft Advisory until 2 am EDT Saturday for anz251.
Small Craft Advisory until 10 PM EDT this evening for anz255.

&&

$$
Synopsis...kjc/nmb
near term...nocera
short term...kjc
long term...nmb
aviation...kjc/nocera/nmb
marine...kjc/nocera/nmb

National Weather Service Glossary of Abbreviations