Area forecast discussion
National Weather Service Taunton Massachusetts
728 am EDT Thursday may 23 2013
Synopsis...
a stalled front across central southern New England will move
north as a warm front later today. Scattered strong thunderstorms
are possible today and Friday. Showery and much cooler weather
will occur for the weekend...with improvements on Monday.
Seasonable temperatures and dry weather for the middle week.
&&
Near term /until 6 PM this evening/...
730 am update...
Scattered showery and isolated thunder continues to fester over
Long Island. These cells continue a northeast path across CT and
Rhode Island into central mass. Expect these showers to continue well
throughout the day. Thinking storm cells will move quickly enough
today to mitigate the occurrence of widespread heavy rainfall.
This potential will still need to be reevaluated by the next
shift.
Previous discussion...
Still rather tranquil across southern New England in comparison.
Lots of stratus with areas of poor visibility in fog and drizzle
to contend with. A frontal boundary still looks to be stalled
along I-90 in Massachusetts. 23/00z guidance has struggled with the movement
of this front...and think the guidance is too quick to push this
front north. Adjusted the timing of this front based on observed
trends for this morning. Current expectation is this front will
push north quickly this morning after sunrise.
Otherwise...expecting a low pressure to move through the Great
Lakes into the Saint Lawrence River valley today. A blend of the
23/00z GFS and NAM looks like a good solution for timing of this
feature. This should leave southern New England in the warm sector
of this low for most of today. Instability should be limited by
the copious clouds to start the day...with some breaks possible
this afternoon. Modest low-level winds could provide enough
organization where some severe thunderstorms are possible...much
like the past couple of days. Areas across the western half of
southern New England will be more at risk for any severe
thunderstorms this afternoon and evening.
Temperatures were a blend of the various MOS products. Did adjust
temperature trends in the near-term to go along with slower timing
of warm front.
&&
Short term /6 PM this evening through 6 PM Friday/...
a slow-moving cold front should plod its way east across southern
New England tonight into Friday. Widespread showers are a near
certainty. A plume of precipitable water values between 1.50-1.75
inches ahead of this front should also mean locally heavy
downpours as well. Enough instability to keep a mention of
isolated to scattered thunderstorms in the forecast through this
period.
Used a blend of the slower 23/00z NAM and the slightly faster 23/00z
GFS for the timing of this cold front. This was also supported
fairly well by the 22/21z sref.
Temperatures were a blend of the various MOS products.
&&
Long term /Friday night through Wednesday/...
highlights...
* wobbly upper level low will keep showers and cooler temperatures for the
weekend.
* Improvements begin on Monday...with dry weather and seasonable temperatures.
* Temperature improvement by the mid-week.
Confidence level/model guidance...low confidence in model
performance...but moderate confidence in the forecast. The
models/ensembles show an upper trough with an embedded closed low
across New England over the weekend. This system will wobble over
the region until pushing out by early next week thanks to ridging
across the Midwest. Have high confidence that a cooler weekend is
in store with moderate confidence on precipitation timing and placement.
Believe Monday will dry out the region with a mainly dry forecast
for the mid-week. Models indicate a warming trend by late week
with temperatures above 80f.
Details...
The weekend...looks like cloudy skies...showers and cool temperatures
are in store for the Holiday weekend. Models continue to slow down
the timing of the elongated trough with an embedded cut off low.
Expect the low to linger across New England before pushing out by
Monday. This low will bring a cold pool over the region allowing
for temperatures to struggle to get into the 60s. Breezy northwest winds
wont help much either. Models are indicating some sort of trowal
feature from the cut off lows cyclogenesis. Still too hard to
pinpoint but believe that areas across the CT valley have the best
potential to see the heaviest precipitation with quantitative precipitation forecast values ranging up to
an 1.5 to 2 inches total for the weekend. Since this particular
region has had several round of convection in the past few
days...and with more on the way...may need to watch for potential
flooding amongst the rivers and low lying areas. Precipitation should
begin to lift Sunday night/early Monday morning. Kept any
indication of thunder out of the grids for this time period as
there if very low instability and cloud cover will limit diurnal
heating. Heavy downpours will be the main threat as precipitable water values
will reach up to an inch.
Monday and beyond...Monday is a transition day from the soggy
cool weekend to a warm...dry mid-week. Upper level low will
continue to push off shore into the Gulf of Maine...allowing for
Midwest ridge to build. Surface high pressure will slide over and
help keep a dry forecast for most of the work week. However cannot
rule out a spot shower or two...especially if sea breezes develops. Temperatures
will increase through the mid-week...with upper 60s for Monday to
upper 70s by Wednesday.
&&
Aviation /12z Thursday through Monday/...
forecaster confidence levels...
Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.
Overview...moderate confidence in timing of ceilings and convection.
Today...moderate confidence. Continued unsettled weather. Fog and
low clouds will slowly lift this morning. The tafs may be too
fast in lifting cigs/vsbys...especially across the coastal plain.
Scattered showers/thunderstorms will regenerate during the day
with more strong storms in the CT valley and central hills.
Thursday night and Friday...low confidence. Very unsettled
pattern with variability between VFR and MVFR-IFR conditions in
showers thunderstorms and fog. Timing of conditions at specific
terminals very difficult to pin down at this time.
Kbos terminal...moderate confidence in trends and ceilings...
mainly due to timing issues of a warm front.
Kbdl terminal...moderate confidence in timing of convection
through the period. Could see brief IFR in an area of thunderstorms and rain.
Potential for hail or wind gusts to 50 knots in isolated thunderstorms
this afternoon and evening.
Outlook...Friday night through Monday...
The weekend...low to moderate confidence. Very unsettled pattern
with variability between VFR conditions and MVFR/IFR conditions in
shra/tsra/fog. Improving conditions late Sunday night into Monday
morning from south to north.
Monday into Thursday...high confidence. VFR. Low confidence on sea
breeze development.
&&
Marine...
forecaster confidence levels...
Low...less than 30 percent.
Moderate...30 to 60 percent.
High...greater than 60 percent.
High confidence today. A front is stalled across the eastern
waters this morning. This front will shift north as a warm front
later today. Southwest winds will increase today with potential
for 25 knots gusts. This wind will cause building seas through the
period with 5-8 foot seas on the southern exposed waters and
possibly the eastern outer waters.
Expect low visibilities in fog and locally heavy showers. Isolated
thunderstorms are also possible.
Tonight-Friday...moderate confidence. A cold front will remain
west of the waters...so expecting south to southwest winds to
remain gusty. Low probability for gale-force gusts. Seas well
above 5 feet...mainly across the outer coastal waters.
Outlook...Friday night through Monday...
The weekend...cold front will linger across the waters as surface
low stays over New England. Expect seas to remain above Small Craft Advisory for most
of the weekend. Gusty northwest bring gusts close to gale force Sat into
Sat night with strong Small Craft Advisory needed for Sunday.
Monday...moderate confidence. Winds and seas will slowly diminish.
&&
Tides/coastal flooding...
astronomical high tides will occur this weekend into early next week.
With surface low wobbling over southern New England Saturday and
into Sunday...expect gusty northerly to northwest winds especially
during the daytimes hours. At Boston...a high tide of 11.9ft will
occur on Friday night at 11:21 PM and 12.2ft early Sunday morning
at 12:12 am. Expect a light southerly winds during the Friday high
tide so this is less than a concern. Looking at the Sunday morning
high tide...northerly to northwesterly winds may help increase the
surge especially for Cape Cod Bay. Right now only expect minor
splashover across north facing beaches. Will need to continue to
monitor and update with the latest forecast guidance.
&&
Box watches/warnings/advisories...
CT...none.
Massachusetts...none.
New Hampshire...none.
Rhode Island...none.
Marine...Small Craft Advisory until 6 am EDT Friday for anz232>234.
Small Craft Advisory until 6 am EDT Friday for anz230-231-236-
251.
Small Craft Advisory until 6 PM EDT Friday for anz235-237-250-
254>256.
&&
$$
Synopsis...Belk/dunten
near term...Belk/dunten
short term...Belk
long term...dunten
aviation...Belk/dunten
marine...Belk/dunten
tides/coastal flooding...
