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Area forecast discussion 
National Weather Service Taunton Massachusetts
339 PM EDT Tuesday Oct 6 2015

high pressure will bring dry weather to southern New England through
Thursday with seasonable temperatures. After cooler temperatures
Thursday...a cold front will bring rain to the region on
Friday...followed by more seasonable weather for the weekend.


Near term /until 6 PM this evening/...
a ridge of high pressure in control will result in mostly clear to
partly cloudy skies tonight along with light winds...bringing
another ideal night of radiational cooling. Went a few degrees
below guidance in the normally cooler outlying locations...where
lows should bottom out in the upper 30s to the lower 40s. Across
the rest of the region...expect mainly lower to middle 40s. The mild
spots will be the urban heat islands of downtown
Boston/Providence...where overnight low temperatures will drop to between
50 and 55. Some patchy ground fog will likely develop in the
typically prone locations late...but should not be widespread.


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

Plenty of sunshine and a relatively dry atmosphere will allow
temperatures to quickly rebound after a chilly start. Afternoon
highs should reach into the upper 60s to the lower 70s. Winds will
be relatively it should be a rather comfortable afternoon
for outdoor activities.

Wednesday night...

A weak cold front will move across southern New England Wednesday
night. Little moisture is available with the will
maintain a dry forecast. Low temperatures will mainly be in the
40s...with some lower 50s across the urban heat island of Boston and
portions of the cape/Nantucket.


Long term /Wednesday night through Tuesday/...
* cold front moving through Friday will bring rain
* more seasonable temperatures expected through the long term
* dry weather and a warming trend for into next week

Overview and model preferences...
northern stream remains in control in a predominantly negative nao/ao
regime through early next week. In spite of this...the overall
pattern across noam trends toward a more zonal flow as Pacific
cutoff begins to flatten persistent ridge in vicinity of the Continental
Divide. The resultant flow pattern will allow Arctic cutoff in
Hudson Bay to slide S and amplify a trough in-situ across the
NE...but not before a strong shortwave ejects east through the
developing cyclonic flow pattern. It will be this feature which
will deliver a widespread rainfall risk for Friday in the form of a
surface cold front. After-which...cooler more seasonal pattern is
expected as the longwave trough slowly lifts into early next week.
Not noticing too many significant differences in deterministic
guidance. In fact...looking at d-prog/d-T...all agree that the
final shortwave will be deeper than it/S own previous runs.


Thursday and Thursday night...
high pressure will gradually be sliding east of the region...with
developing return flow and weak warm advection in it/S wake. Thursday
likely to be mostly sunny looking at moisture the the
column...outside of normal diurnal cumulus...but suspect increasing
clouds during the overnight hours. Cool airmass aloft where 850 mb
temperatures are below +5c...therefore in spite of the sunshine...highs
will remain mainly in the low-middle 60s. Lows fall back into the 40s
and low 50s.

Friday and Friday night...
slow moving cold front associated with progressive but robust
shortwave will be moving across the region especially during the
latter half of the day. This recent slow down noted by a deeper
shortwave than previous runs and the possible development of a
weak mesoscale-low along the front. This is likely a result of weak
convective chances. Indices not really impressive but with
showalters nearing 0...and some modest cape apparent on BUFKIT
profiles...heavier elements can/T be completely ruled out. Precipitable waters
support this as well...nearly 1.50 inches or about 1 Standard deviation
above climatology with k-indices in the middle 30s. Low level jet support there
as well...with a 40-45 knots 850 mb jet moving coincident with the
front/frontal wave. The whole pattern is thankfully somewhat
progressive...but can/T rule out a few spots over-achieving with
precipitation totals. Quantitative precipitation forecast plumes top out around an inch with mean/median
values around 0.30. Widespread quantitative precipitation forecast values will reflect this
thinking. Regarding the low level jet...may have some gusty winds along
with some of the heavy rains and frontal passage. Not expecting
any significant issues...but with fully leaved and potentially wet
trees...could see a few downed limbs. Precipitation gradually ends from
northwest to southeast through the evening hours.

Sat and Sat night...
mainly dry but some indication between deterministic European model (ecmwf) and
ensemble members from both the ecens and gefs that suggest a
secondary frontal wave could force precipitation shield back north from
offshore. Feel that some slight chance probability of precipitation mainly S of the Route
44 corridor will reflect this risk. Otherwise...temperatures back to
slightly below seasonal normals with highs mainly in the upper 50s
to low 60s and lows back closer to the low 40s /isolated upper 30s
possible if enough overnight clearing is achieved/.

Sun into Tuesday...
mainly dry although secondary shortwave moving through New
England could lead to increased clouds mainly late sun into Sun
night. Column is dry will maintain the none probability of precipitation.
Otherwise...gradually increasing temperatures each day from slightly
below normal to above normal by Tuesday. In fact...ensemble
probabilities suggest 850 mb temperatures may fall just shy of 10c...which
could promote a brief return to the 70s by early next week.


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

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

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

High confidence in VFR conditions right through Wednesday night. The
exception will be a few hours of patchy ground fog in the typically
prone locations very late tonight into early Wednesday morning.

Kbos terminal...high confidence in taf. Sea breezes should come to
an end roughly between 23z and 01z this evening.

Kbdl terminal...high confidence in taf.

Outlook...Thursday through Sunday.....

Thursday...high confidence.

Friday...high confidence.
Mainly VFR. Brief MVFR/IFR conditions in any shra/fg.

Sat and sun...high confidence.


forecaster confidence levels...

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

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

Tonight through Wednesday...seas will continue to slowly diminish
through Wednesday afternoon. Therefore...small craft headlines will
gradually be brought down...except across the Easter outer-waters
where 5 foot seas will continue into Wednesday afternoon. Wind
gusts will generally remain 15 knots or less with a weak pressure
gradient in place.

Wednesday night...a cold front crosses the waters Wednesday night.
North to northwest winds may gust into the lower 20 knots behind the
front in the cool air advection pattern...but should remain just
below small craft thresholds for wind gusts. However...long enough
fetch will likely continue to result in 3 to 6 feet across our
Easter outer-waters requiring headlines.

Outlook...Thursday through sun...

Thursday into Friday...high confidence.
Winds will shift to the S-SW by late day Thursday. This will allow the
remnant swell to dissipate below Small Craft Advisory conditions by afternoon.
Therefore...any leftover small craft advisories will be dropped
for a time.

Friday night into Sat...moderate confidence.
After a cold frontal passage Friday evening...winds shift to the
northwest...with gusts approaching 25 knots at times into the day on Sat.
This will lead to wind driven waves around 5 feet as well on the
ocean waters. Therefore...small craft advisories may once again be

Sun...high confidence.
West winds dissipate as high pressure returns. Looks like any small
crafts will be able to be lowered.


Box watches/warnings/advisories...
Rhode Island...none.
Marine...Small Craft Advisory until 8 am EDT Thursday for anz250.
Small Craft Advisory until 6 am EDT Wednesday for anz251-255-
Small Craft Advisory until 4 PM EDT Wednesday for anz254.


near term...Frank
short term...Frank
long term...doody

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