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Area forecast discussion 
National Weather Service Taunton Massachusetts
415 PM EDT Thu Oct 20 2016

a warm front approaches from the south late tonight and will be
accompanied by a few showers and/or drizzle along with areas of fog.
Rain may become more widespread and heavy at times Friday and Friday
night across eastern Massachusetts and Rhode Island as low pressure
tracks across the region. Some wrap around showers are possible Sat
night otherwise becoming blustery...cooler and mainly dry by
Saturday low pressure strengthens across northern New
England into Sunday. Dry but cool and blustery into early next week.


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

4 PM update...

Low pressure tracks across western PA/New York tonight with accompanying
warm front approaching from the south. Column remains dry in the mid
levels however low level moisture increases below 5 kft. Good signal
for areas of drizzle/fog and perhaps a few low top showers. The fog
could locally become dense but not expecting widespread dense fog.
Thus no statements or headlines at the moment.

Dew pts in the 50s now will increase overnight into the 60s. Thus
not as cool as previous nights along with temps rising overnight
given the strong low level moisture and thermal advection.


Short term /6 am Friday morning through Friday night/...

4 PM update...


Still a low confidence forecast as models differ on the spacing and
interaction of northern stream energy and subtropical low offshore.
This is apparent in model wind fields with the NAM and rgem much
farther west with its low level jet. While the GFS and European model (ecmwf) farther
east and weaker. Thus how far west just deep layer tropical moisture
and lift track? Model consensus suggest into eastern Massachusetts and perhaps
Rhode Island by afternoon or late day. Hence greatest risk for a period of
heavy rain will be over this region. Will have to watch this closely
as heavy rain threat could shift just offshore or farther west into
Rhode Island and eastern CT into Worcester Hills.

Meanwhile dry slot overspreads much of CT and western-central Massachusetts.
Although showers ahead of approaching frontal boundary from the west
may impact the Berkshires and Litchfield Hills and eventually the CT
River Valley/I-91 corridor. Thus could be two areas of rain across eastern Massachusetts and another across western portions
of MA/CT...with not much in between.

Expecting entire region to get into the warm sector tomorrow with
dew pts in the 60s and temps in the upper 60s and low 70s. So
definitely not feeling like late Oct. Given warm sector will have to
watch for the risk of a few robust showers or isolated thunder
western CT/Massachusetts given a few hundred joules of cape coupled with deep
layer shear across this area.

Friday night...

Much of the same...risk of showers across eastern Massachusetts associated with
tropical plume of moisture and also western CT/Massachusetts as frontal
boundary approaches. Still uncertainty here on how quick streams
phase. Looks like low pres develops over the region and then bombs
north of our latitude. Impressive mid level trough with negative
tilt toward Sat morning. Despite dry slot approaching could have
widespread low top showers toward morning.

Warm start Fri evening with slow cooling toward Sat morning as
cyclogenesis occurs across the region.


Long term /Saturday through Thursday/...

4 PM update...


* wet weather may continue into Saturday
* temperatures drop below normal Saturday and continue dropping
through Tuesday/Wednesday time frame
* mainly dry weather through this time with a few areas of showers
possible on several days

Models are in good agreement through much of the long term,
particularly on the synoptic scale pattern. There are some
discrepancies, but these are largely on the smaller scale details as
well as timing. Looking at more seasonable or even cooler than
seasonable weather through much of the long term.

Saturday...there are still some placement/timing discrepancies with
the surface low with models placing the low anywhere from south of
southern New England to northern New England to start the day. All
models have it then tracking north into Quebec, but the starting
position will make some difference in wind direction and perhaps
duration of the rain. We do lose the deep layer moisture that we
had on Friday fairly quickly so expect rain to taper down fairly
quickly Saturday.

The larger concern Saturday will be the strong pressure gradient and
decent cold air advection that will result in breezy conditions.
Much of the day should remain below Wind Advisory criteria, but
there are indications that winds will pick up towards the end of the
day. Will continue to watch to see if wind advisories may be needed
for a portion of Saturday. In addition, temperatures will drop back
to near or just below normal levels Saturday, with highs in the
mid 50s to around 60 degrees most locations.

Sunday and Monday...the upper level trough slowly moves offshore and
low pressure moves into the Maritimes while a few shortwaves move
through southern New England. Temperatures will be a bit cooler than
normal and gusty winds will likely continue through at least a
portion of Sunday. Sunny skies will counter the cooler, breezy
conditions somewhat but it will definitely feel like a more typical
October out there. The shortwaves moving through may bring a few
showers to the area as well.

Tuesday and Wednesday...high pressure starts building into southern
New England bringing cooler, dry weather. Temperatures will be 5-10
degrees below normal both days, cool enough to possibly induce some
ocean effect clouds and showers on the cape and islands.

Thursday...shortwave ridging becomes more dominant across southern
New England, allowing temperatures to rebound a bit, though they
stay below normal. Dry weather is expected.


Aviation /20z Thursday through Tuesday/...
forecaster confidence levels.

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

Short term /through Friday night/...

230 PM update...

Thru 00z...high confidence.

A combination of VFR and MVFR with any rain showers likely
confined to northwest Massachusetts and then a chance of showers along the
South Coast of Massachusetts and Rhode Island toward 00z.

After 00z...high confidence on trends but lower confidence on
exact timing and details. Widespread MVFR to start and then
lowering to IFR/LIFR after 02z/03z in drizzle/fog and scattered
showers. Localized low level wind shear possible with light easterly winds at the
surface and southerly winds 20-30 kt developing at 2k ft.

Friday...high confidence on trends but lower confidence on exact
timing and details. Widespread IFR/LIFR conditions persisting in
the morning...possibly lifting to MVFR at times in the afternoon
with rain becoming more widespread. Isold T-storm possible.

Friday night...high confidence on trends but lower confidence on exact
timing and details. IFR/LIFR likely in periods of rain/drizzle
and fog. Isold T-storm possible.

Kbos taf...high confidence in trends.

Kbdl taf...high confidence in trends.

Outlook /Saturday through Tuesday/...

4 PM update...

Saturday...moderate confidence. A mix of conditions in scattered
showers. Westerly winds increase, gusting to 25 to 30 kts. Higher
gusts are possible towards evening particularly on the cape and

Sunday...high confidence. VFR. Gusty northwest winds continue but will
diminish slowly.

Monday and Tuesday...moderate confidence. Mainly VFR. Low
confidence in MVFR/IFR conditions developing on the cape and islands
in ocean effect clouds and rain showers.


forecaster confidence levels.

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

Short term /through Friday night/...moderate confidence.

4 PM update...

Tonight...warm front approaches from the south with areas of drizzle
and fog lowering vsby to less than a mile at times. East-northeast winds 15 to
20 kt becoming southeast with gusts up to 25 kt at times.

Friday...warm front lifts north with low vsby due to drizzle and fog
improving somewhat toward midday. Periods of heavy rain possible in
the afternoon across the eastern waters as subtropical low lifts
north of the Bahamas tonight.

Friday night...low consolidates over southern New England and then
becomes a gale center over central-northern New England Sat. Winds
variable as low tracks over the area. Vsby reduced at times in areas
of rain and fog.

Outlook /Saturday through Tuesday/...

4 PM update...

Saturday and Sunday...high confidence. Small Craft Advisory
conditions will continue with a tight pressure gradient between the
departing low pressure system and building high pressure in the
Great Lakes. Westerly winds will shift to the northwest on Sunday.
Have enough confidence in gale force winds occurring to issue a gale
watch for all southern New England coastal waters for Saturday. This
likely will need to be extended into a portion of Sunday at a later

Monday and Tuesday...moderate confidence. Marginal Small Craft
Advisory conditions continue though both winds and seas will
diminish gradually through the period as the pressure gradient


Tides/coastal flooding...

4 PM update...

Astronomical high tides are subsiding with each tidal cycle. There
may still be a small risk of minor splashover at the more
vulnerable spots on the coastline during the Fri evening high tide
cycle, but the general trend is now moving away from that.


Box watches/warnings/advisories...
Rhode Island...none.
Marine...gale watch from Saturday morning through Saturday evening for
Small Craft Advisory until 8 PM EDT Friday for anz250-254.
Small Craft Advisory until 8 PM EDT Friday for anz255-256.


near term...nocera
short term...nocera
long term...rlg
tides/coastal flooding...staff

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