BOX issues Area Forecast Discussion (AFD) at Oct 19, 10:24 AM EDT171
FXUS61 KBOX 191424
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
1024 AM EDT Sat Oct 19 2024
.SYNOPSIS...
Strong high pressure settles over the Northeast states today
into midweek, bringing dry conditions and warmer temperatures
this weekend through much of next week. Temperatures will be
well above normal. Change in air mass Thursday with the passage
of a front which may bring our next chance for light rain.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
1015 AM Update:
Gorgeous morning in progress, with abundant sunshine and light
winds, as 1034 mb high over NY slowly advects over New England.
Warm temps aloft (already 64 at ORH) will mix down to the
surface as cool shallow surface layer erodes with increasing sun
angle late morning into early afternoon. Highs climb well above
normal (about +10 degs), with temps peaking in the upper 60s
and lower 70s this afternoon. Slightly cooler along the coast
and islands with highs topping off in the low to mid 60s, as
seabreezes develop with SST in the upper 50s and lower 60s. Very
comfortable with dew pts in the 30s this afternooon. Only change
from previous forecast, was to expand the special weather
statement across the entire region, for elevated fire weather
parameters. Despite light winds today, concern is high
recreation given ideal weather this weekend. Earlier discussion
below.
Previous discussion:
The weather across Southern New England continues to be governed
by a strong area of high pressure and anomalously high 500 mb
heights/ridging. Large-scale subsidence associated with these
features are supporting clear skies and generally calm winds.
Wide range of observed temps early this morning, as low as 30
degrees to as "mild" as the upper 40s.
Today is shaping up to be a spectacular day with hardly a cloud
in the sky and above normal temperatures associated with the
strong ridge aloft. 925 mb temps reach around +12 to +14C today
and with the protracted spell of drier weather we've had and
lighter WSW winds, temperatures should soar today. The forecast
850 mb temps around 10-12C under full mixing would support some
areas hitting 80 degrees, but the main limiting factor to go
any higher than the mid 70s was that mixing looks shallow. While
we are not in jeopardy of breaking daily record high temps at
our four climate sites, these are still some 15 degrees warmer
than late-October normals! Coastal areas today should reach
highs in the mid to upper 60s, with a potential for a seabreeze
early in the afternoon with less than 10 kt of flow through a
large depth of atmosphere.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM SUNDAY/...
300 AM Update:
Tonight and Sunday:
We'll still be under influence of strong ridge of high pressure
both at surface and aloft, though it will tend to flatten and
shift southward into Sunday.
So for tonight, expect another evening of near ideal radiational
cooling with very dry air, clear skies and light winds. However
it should be quite a bit warmer than we've been, considering the
warm daytime and that forecast 850 mb temps around +12C are
exceeding the climatological 90th percentile at ALB as per SPC's
sounding climatology. Most areas should only fall into the lower
to mid 40s, though a few mid to upper 30s could be possible in
northwestern MA.
Sunday should be essentially a repeat of Saturday. In other
words, another day with full sun and highs reaching the lower to
mid 70s, with mid/upper 60s near the coast. Thus, should be
great for any outdoor plans, though will be some 15 degrees
warmer than normal compared to a typical late October day. The
only real nuanced change is that WSW winds end up being a touch
stronger than today, but it won't be by very much and for many,
that change will hardly be perceptible.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Highlights:
* Tranquil conditions thanks to expansive high pressure across the
northeast, bringing dry conditions and warmer temperatures through
Wednesday.
* Change in air mass Thursday with the passage of a front which
may bring our next chance for light rain.
Global deterministic guidance remains in consensus that mid-level
ridging and surface high pressure are the primary weather feature
through Wednesday. Around Thursday, signs the mid-level ridge breaks
down and a mid-level trough/cold front approaches from the west.
This would be the next chance for rain. Now, probabilites are low
for 0.1", between 10% and 30% based on the GEFS, between 30% and 50%
based off the CMC ENS, and between 20% and 30% based off the ECMWF
ENS. Given this part of the forecast is nearly a week out, continued
with NBM POPs, which paints a picture of 'slight chance' to at best
'chance' across the CWA.
Mostly sunny skies Monday through Wednesday are accompanied by above
normal temperatures, warmest likely on Monday and Tuesday. Both days
could have high temperatures well into the 70s. Warmest afternoon
highs are in the Connecticut River Valley, middle 70s. One caveat
with Tuesday, should have a sea breeze, keeping the coastal areas
cooler in the upper 60s. Temperatures should be a few degrees cooler
on Wednesday with slightly cooler temperatures aloft, highs are
generally in the lower 70s. With the mid-level ridge breaking down,
a return of more seasonable temperatures in the low 60s by next
Thursday. And by Friday, highs are in the low to middle 50s.
Sunday night into Monday morning will still feature cold overnight
lows. Areas prone to radiational cooling could return to the low 30s
with patchy frost. Rest of the week, overnight lows are upper 30s
across the interior and areas that typically radiate while the rest
of the region are 40s to lower 50s at the immediate coast. Thursday
night, post cold front, temperatures should cool off, returning the
widespread 30s.
&&
.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
15z TAF Update: no change from previous issuance. VFR, dry
weather and light/variable winds, locally onshore near the
coast. Earlier discussion below.
==========================================================
Today: High confidence overall, though moderate on wind
direction at BOS.
VFR. Winds shift from light WNW to SW around 5-8 kt. With very
weak winds within the lowest 2000 ft, seabreeze could develop at
BOS. If it were to develop, it would likely not do so until
early afternoon (around/after 16z) and it may also oscillate
between WSW and SE, before becoming SSW after 22z Sat.
Tonight: High confidence.
VFR. Light SW winds to trend light W overnight. Winds may go
calm at times.
Sunday: High confidence.
VFR. SW winds around 5-10 kt. Seabreeze at BOS looks unlikely.
KBOS TAF...High confidence in TAF overall, though moderate on
if a seabreeze can develop. Winds to become SW around 5-8 kt
today, though a potential seabreeze could flip winds to SE after
16z thru 22z.
KBDL TAF...High confidence in TAF. VFR. Light SW winds.
Outlook /Sunday through Wednesday/
VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
305 AM Update:
Overall high confidence.
SCAs continue in effect through later Saturday night for the
outer offshore waters as built-up seas begin to gradually
subside. Winds mainly light SW today through Sunday with speeds
around 10 kt or less. Seas gradually lower today through Sunday,
falling below 5 ft on all waters by late tonight, and becoming 4
ft or less for Sunday.
Outlook /Sunday Night through Wednesday/...
Winds less than 25 kt.
&&
.FIRE WEATHER...
715 AM Update:
Above normal temperatures and full sunshine will boost
temperatures into the 70s today. Dewpoints in the mid 20s to
mid 30s should bring relative humidities down to 25 to 30
percent today. When combined with the protracted dry spell/lack
of rainfall, it has led to elevated fire weather concerns. The
one mitigating factor is that winds will be quite a bit lighter
than yesterday, mainly southwest around 5-10 mph. Input from our
fire weather partners in Connecticut has led to a special
weather statement for fire weather concerns valid thru 700 PM.
We have also reached out to our forestry partners in
Massachusetts and Rhode Island and will await their feedback
before making a determination if an SPS is needed for those
states.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ250-
254>256.
&&
$$
SYNOPSIS...Loconto/Dooley
NEAR TERM...Loconto/Nocera
SHORT TERM...Loconto
LONG TERM...Dooley
AVIATION...Loconto/Dooley/Nocera
MARINE...Loconto/Dooley
FIRE WEATHER...Loconto
Source:
BOX issues Area Forecast Discussion (AFD) at Oct 19, 10:24 AM EDT----------------
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