BOX issues Area Forecast Discussion (AFD) at Oct 17, 3:15 PM EDT413
FXUS61 KBOX 171915
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
315 PM EDT Thu Oct 17 2024
.SYNOPSIS...
High pressure builds in starting Friday with a warming trend through
early next week. Chilly nights will transition to mild afternoons as
high temps climb into the mid 70s by early next week. Not much on
the horizon when it comes to precipitation.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Low pressure to our southeast will begin to retreat to sea which
will take the mid to high level clouds that burdened much of SE MA
and RI today with it. While it will be clear overnight tonight for
most, winds will stay more elevated compared to the last few nights,
which will stunt radiational cooling for most of the region; save
for far NW MA where winds may decouple thanks to being furthest from
the coastal low. Do expect most to stay above freezing outside of
the northern Connecticut River Valley, with 40s expected along the
coast. 705 AM Update:
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/...
Friday...
Friday will be a transitional day with low pressure still southeast
of the benchmark for the first half of the day. High pressure and
strong ridging building from the southwest will nudge the low
further southeast. While the synoptic setup will be transitioning
towards a more favorable, at least if you like 70s and sunny,
pattern, surface flow on Friday will continue to be influenced by
the low to our southeast, thus, we won't warm as quickly as some may
hope tomorrow with winds continuing to blow from the NNE. It will be
another blustery day, with winds gusting in excess of 20mph along
the coastline, which will certainly have an impact on temperatures
with SSTs now in the upper 50s and low 60s. Overall, should tack
several degrees onto temps compared to Thursday, with highs
generally expected to range from the low to mid 60s, though portions
of the CT River Valley may make a run at the upper 60s as 850mb
temperatures climb to ~8C by late afternoon. Cloud cover should be
less, particularly across SE MA and RI, tomorrow as low pressure
drifts out to sea.
Friday Night...
Friday night will have the potential to be another great radiator as
winds fall off across interior southern New England; though the best
radiative potential will be north of I-90 as winds try to maintain
between 5-10mph along the I-95 corridor, and between 10-15mph across
the Cape and Islands. Do think that most will stay above the
freezing mark overnight, but places like Orange and Chicopee will
make another run at 32F. As mentioned, winds should keep most of the
eastern MA radiators, like OWD and TAN, above freezing, but mid to
upper 30s are again possible for portions of metro-west. Urban
heating and an inversion will keep temps near or above 40 in most
urban centers and across the high terrain.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Key Points:
* Warm and dry into mid-week
Latest output from the Global models continue to show a powerhouse
ridge locked in place across much of the eastern half of the country
from this weekend all the way into mid-week. With the run-to-run
consistency in the models, this makes for a high confidence
forecast. Went with the NBM, although adjusted a little colder by
blending in the NBM25th percentile guidance for Saturday Night and
Sunday Night given expected good radiational cooling conditions.
This would put overnight lows into the low-mid 30s in many areas
(especially the normally colder spots). That means some frost is
possible, so if you still have non-native plants on your deck (like
palm trees and banana plants), you'll have to take action to protect
them again. Otherwise the aspect of the weather that will be most
noticeable to everyone will be the warming conditions. 925mb
temperatures on Saturday will be 11-12C -- which supports surface
high temperatures into the upper 60s. Westerly flow and
subsidence will help to warm those temperatures a couple of
degrees Sunday and then again Monday. Thus by Monday we will be
looking at widespread mid to upper 70s for highs, although
cooler across the Cape and Islands and perhaps the immediate
coast if we get a seabreeze. Flow looks to turn more onshore for
Tuesday, so although mid-upper 70s are still expected inland,
along eastern areas temperatures will be moderated somewhat.
Still, temperatures will be well above normal. Some hints that
the upper air ridge starts breaking down later Wednesday or
Thursday. Thus somewhat cooler temperatures and perhaps a small
chance for showers.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
18z TAF Update:
Through tonight... Generally VFR except across SE MA and RI
(generally from I-95, southeast) where a cloud deck around 3k ft
will continue to impact terminals this afternoon. Borderline
MVFR cigs will gradually pull to the southeast, with conditions
improving to VFR from 21 to 00Z, with ACK the last to improve.
Dry, with brisk ENE winds gusting to between 10-20kt with winds
subsiding away from the coast this evening as they gradually
shift to the north. Isolated shower possible for ACK.
Tomorrow and tomorrow night...
VFR with N/NE winds that may shift to the NW just prior to
Sunrise on Saturday. Gusts to 20kt possible again during the day
on Friday.
KBOS TAF...High confidence. VFR.
ENE winds gusting to around 15kt this afternoon slacken,
becoming more northerly overnight. Winds pick up again on
Friday, gusting to as high as 20kt, from the N/NE. VFR, though
borderline MVFR cloud deck to hang around the terminal Thursday
afternoon.
KBDL TAF...High confidence. VFR. N/NE winds gusting to as high
10kt today and 15kt on Friday. .
Outlook /Friday Night through Monday/
VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
400 AM Update:
A distant coastal low pressure will lead to increasing NE winds
and building seas starting late this afternoon and continuing
into later Friday night or Saturday. Small craft advisories
have been posted starting late this afternoon over the southern
waters, and early this evening over the eastern waters.
NE wind gusts increase to around 20-25 kt late this afternoon
over the southern outer waters, and become around 25-30 kt
tonight into Friday. For the eastern waters, NE winds reach the
20-25 kt range early tonight, staying around that range before
slowly decreasing into later in the day on Friday. Wave heights
to build to around 5 to 9 ft for the offshore waters later today
and continuing into Friday.
Outlook /Saturday through Tuesday/...
Saturday through Saturday Night: Winds less than 25 kt. Seas up
to 5 ft.
Sunday: Winds less than 25 kt. Seas locally approaching 5 ft.
Sunday Night through Tuesday: Winds less than 25 kt.
&&
.TIDES/COASTAL FLOODING...
Coastal flooding will be the one wildcard on Friday, particularly
during the Friday mid day high tide, but it appears to be highly
dependent on the proximity of low pressure. High astro tides - with
Boston already at approximately 12.0 ft, will drive most coastal
flood prone areas to "near flood". Aforementioned blustery
NE/ENE winds may be the straw that breaks the camel's proverbial
back, leading to storm surge between 0.5-1.0ft. The lower bound
of forecasted surge puts most of our coastline safely in
"Coastal Flood Statement" territory, but given the potential for
up to a foot of surge, opted to issue a Coastal Flood Advisory
for the eastern MA coast as well as the Islands, mainly as a
safeguard against the upper bounds of the forecast. In general,
expecting minor splashover in places like Morrissey Blvd as well
as on ACK.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Coastal Flood Advisory from 10 AM to 3 PM EDT Friday for
MAZ007-015-016-019-022>024.
RI...None.
MARINE...Small Craft Advisory from 11 PM this evening to 8 PM EDT
Friday for ANZ231>235-237-251.
Small Craft Advisory from 11 PM this evening to 11 PM EDT
Friday for ANZ250.
Small Craft Advisory until 8 AM EDT Saturday for ANZ254>256.
&&
$$
SYNOPSIS...KS/Nash
NEAR TERM...KS
SHORT TERM...KS
LONG TERM...Nash
AVIATION...KS
MARINE...KS/Nash
TIDES/COASTAL FLOODING...
Source:
BOX issues Area Forecast Discussion (AFD) at Oct 17, 3:15 PM EDT----------------
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