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Area Forecast Discussion
National Weather Service Taunton MA
727 AM EDT SAT JUL 23 2016

.SYNOPSIS...
Hot conditions continue today, along with another risk for
thunderstorms this afternoon, some of which may become severe. An
approaching cold front will bring another round of scattered
showers and thunderstorms from Monday into early Tuesday. More
warm weather follows midweek.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Mostly minor tweaks to bring the forecast back in line with
observed trends.Some patchy fog across southeast MA will dissipate
soon. Otherwise, plenty of sunshine to begin the process of
increasing instability.

Previous discussion...

Pre-frontal trof is currently shifting through central S New
England as initial upper lvl shortwave/associated cold pool are
moving offshore. While some moderate convection continues in
advance, the bulk of this should remain offshore for the rest of
the morning hours. Very weak post convective ridging is clearing
things out to the NW.

This clearing will allow for atmospheric reloading, so-to-speak, 
through the morning. In fact, guidance is likely underdoing
today's diurnal destabilization as progged dwpts/temps are
initializing lower than current obs suggest. H85 temps only drop
to about +18C, so another day (given plenty of sunshine to start)
with temps in the upper 80s to low-mid 90s is likely. Dewpoints
only drop into the upper 50s to mid 60s behind the stalling
boundary.

Other than heat, will need to monitor for another round of
potential severe weather today, thanks to another round of
instability with ML CAPE values near 1200 J/kg. Very acute
shortwave combined with H5 temps dropping to near -13C suggest one
last taste of the remnant EML which helped convection overnight.
Noting mid level lapse rates will approach 7.0 C/km with this
upper level cold pool.

Therefore primed for another round of TS today, peak timing of the
shortwave suggests a slightly earlier start/end, mainly 18Z (2 PM)
to 01Z (9 PM). Primary issue will once again be wind, as mean
shear exceed 40 kt with H92 winds nearly 40 kt, and high D-CAPE
values thanks to a well mixed BL. Would not be surprised to see
localized downburst and straightline wind damage similar to
Friday evening. Although this shear could allow for storm
organization, tornado risk should once again be low thanks to very
high LCLs and a well mixed BL.

Hail also a risk, as high lapse rates once again support hail CAPE
values mainly +300 J/kg. Therefore, stay tuned to forecast
updates through the morning as this thinking correlates to latest
SPC SWODY1 Marginal Risk.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/...
Thunderstorms/showers should end earlier than Friday night thanks
to faster movement of the forcing shortwave. Drier air will lead
to some drying during the overnight but leftover convective debris
cloudiness will likely keep temps from dropping too far. Expect
mins mainly in the 60s. A few spots of fog possible, especially
where late day rainfall is observed.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Overview...

Not much change from the previous model cycle. High pressure
covers much of the southern USA for most of next week. This will
mean any fronts will struggle to get very far south of our region
next week. Mid level flow transitions to a near zonal flow by
early next week, then to a broad trough by mid week. Temperatures
should generally be above seasonable levels most of this portion
of the forecast.

Details...

Sunday...

High pressure in place through the day. Winds appear to be light
enough where seabreezes may develop along both coasts. Moderate
confidence in seabreezes. Above normal temperatures continue for
most of southern New England.

Monday...

A mid level shortwave moves across our region late Monday into
Monday night. Most of the day should be rain-free. Some signs of
marginal instability crossing during the morning, which may be a
warm front with a couple of light showers. Greater instability
moves in from the west during the afternoon and evening, in the
warm sector ahead of a cold front. Precipitable water values
remain high, so locally heavy rainfall is still possible in
stronger thunderstorms. Scattered showers and thunderstorms should
continue into Monday night as a cold front passes by.

Tuesday and Wednesday...

High pressure takes control and brings fair weather. Above normal
temperatures continue. 

Thursday and Friday...

Latest operational guidance continues to indicate some potential
for showers, largely due to a stalled front to our south, and
another cold front approaching from the north. Still have low
confidence in the details. Will continue to mention a chance of
showers and thunderstorms due to the presence of these boundaries.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels.

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

Short Term /through Tonight/...

Today...moderate confidence.
VFR through at least 18Z. Then another risk for sct TSRA possible
mainly E of a line from kEEN-kORH-kWST. Some strong winds possible
once again in some of these storms. Otherwise, winds mainly W-SW
10-15 kt.

Tonight...High confidence.
Mainly VFR after any storms/showers end through the overnight
hours.

KBOS TAF...Moderate confidence. Another round of thunderstorms is
likely this afternoon to early evening. Some of those storms could
produce strong wind gusts.

KBDL TAF...High confidence of VFR prevailing. There could be some
patchy fog with MVFR visibility through 12Z.

Outlook /Sunday through Wednesday/...

Sunday...High confidence mostly VFR. Possible areas of IFR in
early morning fog.

Monday...Moderate confidence. Mostly VFR. Possible IFR in early
morning fog. Brief MVFR/IFR cigs/vsbys in afternoon and early
night showers/thunderstorms.

Tuesday and Wednesday...High confidence VFR.

&&

.MARINE...
Forecaster Confidence Levels.

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

Short Term /through Tonight/...High confidence.

Seas will continue to dissipate through the morning as winds
outside of thunderstorms have already dropped to or below 20 kt.
Seas will also gradually dissipate this morning allowing the
remaining small craft advisories to be dropped.

Otherwise, another round of showers and thunderstorms are possible
over the waters this afternoon and evening which could contain
localized strong wind gusts.

Outlook /Sunday through Wednesday/...Moderate confidence.

Winds less than 20 knots and seas less than 5 feet through this
period. A cold front will bring scattered showers/thunderstorms
Monday afternoon and night, with potential for strong wind gusts
and brief poor vsbys in heavy downpours.

&&

.EQUIPMENT...
The KBOX radar is down for maintenance. Technicians will try to
return the radar into service by no later than 3 PM this
afternoon.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ235-
     237-255-256.

&&

$$
SYNOPSIS...Belk/Doody
NEAR TERM...Belk/Doody
SHORT TERM...Doody
LONG TERM...Belk
AVIATION...Belk/Doody
MARINE...Belk/Doody
EQUIPMENT...Belk

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