BOX issues Area Forecast Discussion (AFD) at Sep 2, 10:01 AM EDT739
FXUS61 KBOX 021401
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
1001 AM EDT Mon Sep 2 2024
.SYNOPSIS...
Dry and very pleasant weather persist through the end of the
work week, with temperatures moderating by Thursday/Friday.
Potential for our next rainmaker to develop next weekend.
&&
.NEAR TERM /UNTIL 7 PM THIS EVENING/...
* Beautiful today with partly sunny skies & very comfortable
humidity levels...high temperatures between 75 and 80
10 AM Update...
Post frontal airmass has overspread the region this morning,
with some fall vibes in the air, as dew pts fall into the 40s
and 50s, along with a modest northerly breeze. Canopy of
mid/high clouds streaming SW to NE across CT/RI and eastern MA
this morning, will slowly exit eastward this afternoon, as mid
level flow becomes more westerly. HREF cloud cover captures this
very well. Thus, decreasing clouds this afternoon for this
region. Farther inland across western-central MA, mostly sunny
conditions this morning will give way to scattered diurnal
CU/SCU this afternoon. Overall, beautiful weather for the
holiday.
Tonight...core of cool/dry air advects across the region late
tonight, as robust northern stream s/wv traverses from southern
Quebec to Maine and then into the Maritimes. 850 mb temps over
SNE go from +11C Monday morning to +4C Tuesday morning. This
will yield widespread lows in the 40s overnight, about 10 degs
cooler than normal. To put this into perspective, the last time
overnight temps fell into the 40s at KBDL, was late May. The
urban areas of Boston, Providence and Hartford, will not be
quite as cool, but nonetheless lows in the low to mid 50s.
&&
.SHORT TERM /7 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Key Points...
* Dry/Chilly tonight...lows mainly in the 40s with lower to middle
50s in some of the urban centers as well as the Cape & Islands
* Sunny & beautiful weather Tue with highs in the lower to middle
70s with very comfortable humidity levels
Details...
Tonight...
Large high pressure over the midwest gradually builds eastward
tonight as a secondary dry cold front crosses the region. This
coupled with a dry airmass in place will result in chilly
temperatures tonight. Overnight lows should bottom out in the lower
to middle 40s in the normally coolest outlying locations...to the
lower to middle 50s in the urban centers of Boston and Providence.
Northerly winds will be a bit breezy on the Cape & Islands with the
cool airmass transferring over the relatively mild ocean. This
should keep overnight low temps in the lower to middle 50s across
the Cape and Islands.
Tuesday...
Large high pressure will be in control of our weather Tuesday.
Despite the chilly start...sunny skies and a dry airmass in place
will result in nice recovery in temperatures. Afternoon highs should
reach the lower to middle 70s with light northwest winds and very
comfortable humidity levels.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
* Dominant high pressure remains in place through late week
* Gradual warming trend brings temperatures closer to average by
late week
* Unsettled conditions likely next weekend, though the period will
need to be watched
Sprawling high pressure remains in place through Friday before
trough digs south from the Great Lakes next weekend. Guidance is in
generally good agreement that surface low will track near or over
southern New England in the vicinity of Saturday, which combined
with approaching trough will yield our only real rain chances during
the long term period.
Tuesday night/Wednesday morning will feature another round of
seasonably chilly lows with high pressure directly overhead. While
radiational cooling conditions will be optimal, lows will be several
degrees warmer than what we expect on Tuesday morning as dewpoints
are forecast to be some 5 degrees or so higher, in the mid 40s. Same
record on repeat for Thursday and Friday as dewpoints gradually
begin to climb into the low 50s, resulting in moderating
temperatures late week. Cold pool that persists over southern New
England early this week shifts to our east Wednesday-Friday allowing
850mb temperatures to warm back to between 9-11C, supportive of
highs in the upper 70s to around 80. Temps are expected to warm
quickly each morning given drier airmass in place, but some morning
radiation fog, primarily in the CT River Valley, each morning could
delay warming a few hours.
Aforementioned surface low/incoming trough for the weekend
drives an unsettled pattern. While a bit early to determine
exactly how much rain we could see, both deterministic and
ensemble Euro, GFS, and Canadian guidance hints at the potential
for 1-2" of rain, with the Canadian ensemble showing up to a
50% chance of 1" of QPF Saturday into Sunday across interior
southern New England. This period bears watching over the next
several days.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
15z TAF Update...only change to the forecast is for KBOS,
seabreeze direction this afternoon from roughly 16z-20z (plus or
minus an hour) will be more from the NE than east. Otherwise,
VFR, dry weather and local seabreezes for coastal terminals.
Earlier discussion below.
====================================================================
Today...High Confidence.
VFR today with NNW winds around 10 knots with a few gusts
between 15 and 20 knots. The exception might be on the immediate
eastern MA coast/Cape and Islands...where winds should turn NE
or even localized sea breezes for a few hours between
approximately 16 and 20Z.
Tonight and Tuesday...High Confidence.
VFR conditions with N-NW winds generally 10 knots or less...but
some 20+ knot wind gusts possible tonight across Cape and
Islands.
KBOS TAF...High confidence in VFR. The only uncertainty is wind
direction and we think there may some sort of NE or E sea breeze
for a few hours during the afternoon.
KBDL TAF...High confidence in TAF.
Outlook /Tuesday Night through Friday/...
Tuesday Night through Thursday Night: VFR.
Friday: VFR. Breezy.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Today...High Confidence.
Areas of fog should scour out quickly by daybreak across our
southern waters behind the cold front. N winds of 10 to 15
knots with some 20+ knot gusts for the first part of the day
should shift to the NE and diminish a bit later.
Tonight...High Confidence.
A secondary cold front crosses the region early this evening. This
will result in a period of NNW wind gusts up to 25 knots for a few
hours. The cool airmass should mix well over the relatively mild
ocean...so we hoisted a small craft advisory for most of our open
waters tonight.
Tuesday...High Confidence.
N winds of 10 to 15 knots will begin to diminish on Tue as high
pressure builds in from the west. Winds and seas will be back below
small craft advisory thresholds.
Outlook /Tuesday Night through Friday/...
Tuesday Night through Thursday Night: Winds less than 25 kt.
Friday: Winds less than 25 kt. Areas of seas approaching 5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 8 PM this evening to 8 AM EDT
Tuesday for ANZ231>235-237-250-251-254>256.
&&
$$
SYNOPSIS...Frank/KS
NEAR TERM...Frank/KS/Nocera
SHORT TERM...Frank
LONG TERM...KS
AVIATION...Frank/KS/Nocera
MARINE...Frank/KS
Source:
BOX issues Area Forecast Discussion (AFD) at Sep 2, 10:01 AM EDT----------------
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