Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Taunton Massachusetts
448 PM EDT Thursday Jul 31 2014

a few hit and miss showers/thunderstorms are expected this
evening across southern New Hampshire and western Massachusetts. Scattered showers and
isolated thunderstorms expected again Friday afternoon...mainly
northwest of I-95. The weekend forecast remains uncertain...but
the potential for periods of wet weather continues. Seasonable
temperatures are then expected early next week


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

..a couple of strong storms are possible across southern New Hampshire and
extreme northern Massachusetts into early this evening...

4 PM update...

This evening...widely scattered showers/thunderstorms across the New York to
New England region. Most of the activity is in New Hampshire into
Maine...associated in part with a potent short wave that is lifting
northeastward into northern New England. Storm Prediction Center mesoanalysis indicates
MUCAPES 500 to 1000 j/kg across most of southern New England...with
the higher cape values over southern New Hampshire into western Massachusetts. Somewhat
warmer air is moving in at the middle levels...which is contributing to
lower instability. However some strong storms are still possible
across southern New Hampshire into extreme northern Massachusetts for a few more hours.
Elsewhere...widely scattered to isolated showers/thunderstorms
possible until around sunset. Diminishing cloud cover is
expected...with skies becoming mostly clear.

Tonight...diurnal convection ends early...with high pressure
centered offshore winds are expected to become light SW. There may
be patchy lingering convective debris clouds that cross our
area...otherwise mostly clear skies expected tonight. Good
radiational cooling with winds becoming light...temperatures should dip
into the middle 50s to low 60s across most locales.


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

Friday...high pressure remains centered offshore...with a deep
upper trough lingering over eastern Canada into the Great Lakes
region and Mississippi Valley. This places our area in SW
flow...and the models are indicating a moisture rich environment
upstream in the southeastern U.S. This will bring a gradual
increase in moisture across our area Friday into Friday night.
During Friday some afternoon diurnal convection is possible...cape
increasing to a few hundred j/kg across the interior. A short wave
moving through the area may assist as a trigger. Shear is less
than today and 500 mb temperatures are not as cold.

Friday night...increasing moisture continues. An offshore front
is expected to back westward towards our coastline...and models
indicate the potential for an open wave developing along this
front. Over the course of the night increasing clouds are
expected...with rain/showers possible late. There is some
uncertainty on the placement of the low for 12z Sat...generally
between the Carolinas and middle Atlantic coastline.


Long term /Saturday through Thursday/...
* steady rain likely sometime this weekend
* showers and thunderstorms possible early next week

The models are in fairly good agreement through most of this
portion of the forecast. However...there are definitely
differences both in the details and also in parts of the synoptic
pattern...particularly around the potential system this weekend.
Used a blend of available guidance for much of this portion of the

Saturday and Sunday...a middle level trough shifts a bit to the west
this weekend...allowing for subtropical moisture to move up the
East Coast. This westward shift drags a nearly stationary front
west toward southern New England. Combined with the moisture...
expecting a fairly steady rainfall across at least a portion of
southern New England through part of this weekend. There are still
differences in the models...both in the westward extent of this
front and in its timing. Depending on the ultimate resolution of
these details...the forecast could require significant changes.

Monday and Tuesday...stationary front slowly shifts back offshore
bringing at least a temporary end to the risk for steady rainfall.
However...low pressure moving through Quebec will bring a cold
front towards southern New England. Expecting the possibility for
showers and thunderstorms periodically.

Wednesday...high pressure builds in behind the cold front. Cooler
but quiet weather is expected.

Thursday...another wave of low pressure arrives from the
west...pushing a front closer to our region. This should lead to
a slight increase in rainfall chances.


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...tonight through Friday night...

Early this evening...high confidence in mainly VFR conditions. A
few hit and miss showers/thunderstorms expected this
afternoon...with the highest risk across northwest Massachusetts/southwest New Hampshire.
This activity may result in briefly lower cigs/vsbys.

Tonight...moderate to high confidence. Mainly VFR conditions other
than patchy ground fog possible late in the typically prone

Friday...high confidence in mainly VFR conditions. A few hit and
miss showers and thunderstorms possible during the
afternoon...mainly northwest of I-95. This activity may result in
briefly lower conditions.

Friday night...moderate confidence VFR conditions. Low chance of
MVFR ceilings/visibilities in scattered showers.

Kbos taf...high confidence in VFR conditions. Very low probability
for a thunderstorm moving over the terminal this afternoon. Sea
breeze is expected to develop during Friday towards midday.

Kbdl taf...high confidence in taf. Very low probability for a brief
shower thunderstorm to move across the terminal this afternoon.

Outlook...Saturday through Tuesday...

Saturday through Sunday...moderate confidence. Mainly VFR
northwest...chance for MVFR ceilings/visibilities in scattered showers. MVFR
conditions more probable towards eastern Massachusetts/Rhode Island in -shra.

Monday and Tuesday...moderate confidence. Mainly VFR. Low
probability of MVFR/IFR conditions in scattered -shra/tsra...mainly
during the afternoon and evening hours.


forecaster confidence levels...

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

Short through Friday night...

High confidence. Upper level ridge just east of the waters will keep
winds/seas below Small Craft Advisory levels through Friday
afternoon with good visibilities. In addition...winds/seas expected
to remain below Small Craft Advisory thresholds Friday night.

Outlook...Saturday through Tuesday...

High confidence. Relatively quiet boating weather expected with
respect to winds and seas. Rain is likely for a time through a wavering stationary front near or over the waters.
The main impact will be reduced visibility. Drier weather
expected both Monday and Tuesday...with only the threat of an
isolated shower or two across the waters.


Box watches/warnings/advisories...
New Hampshire...none.
Rhode Island...none.


near term...nmb
short term...nmb
long term...Belk

National Weather Service Glossary of Abbreviations