BOX issues Area Forecast Discussion (AFD) at Jan 21, 12:09 PM EST550
FXUS61 KBOX 211709
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
1209 PM EST Tue Jan 21 2025
.SYNOPSIS...
An arctic airmass will persist through Wednesday night with
moderating temperatures Thursday into the weekend although still
below normal temperatures. An ocean storm tracking well south
of New England may bring light snow accumulations to the outer
Cape and Islands tonight followed by clearing Wednesday.
Generally dry conditions are expected during the end of the week
and into next weekend, but we will have to watch another
distant ocean storm Thursday night which could bring light snow
to SE New England if it tracks further north and west.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages:
* Continued very cold today with increasing clouds
Northern stream trough approaches from the Gt Lakes today. A plume
of mid-upper level moisture ahead of the trough will overspread the
region today from the SW leading to increasing mid-high clouds
through the morning and especially in the afternoon. 925 mb temps
around -15C today will only allow temps to recover through the teens
interior, and into the lower 20s across SE MA and coastal RI. A
modest west wind 10-15 mph will result in max wind chills in the
single numbers and teens this afternoon.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Key Messages:
* Bitter cold again tonight with below zero temps interior MA. Cold
weather advisory in place for the Berkshires
* Light snow accumulations likely tonight over the outer Cape and
especially Nantucket
Tonight...
Split flow upper level pattern with southern stream wave moving off
the SE US coast while northern stream trough moves into New Eng.
Phasing is not expected, but the northern stream is a bit more
amplified and guidance has trended northward with plume of deeper
moisture lifting north from the ocean. This will likely bring a
period of light snow to the Cape and Islands tonight, especially
from Nantucket to the outer Cape as the column saturates in this
region with modest lift assocd with the northern stream trough.
Accumulations of 1-2 inches are possible from Chatham to Nantucket.
There is some risk for 3 inches at Nantucket if northward trend
continues, but confidence in this scenario is low. NSSL-WRF is the
most robust of the hi-res guidance but rest of the HREF suite is a
coating to 2 inches. A brief period of light snow or flurries may
make it into the south coast of RI and MA but no accum is expected
here.
Otherwise, expect clearing skies to develop from NW to SE through
the night, with clearing not reaching the Cape and Islands until
near daybreak. Light NW winds will allow good radiational cooling to
develop, especially late evening and overnight. Expect widespread
subzero lows interior MA, with single numbers elsewhere, but teens
outer Cape and Islands where clouds will linger. Just enough wind
for wind chills approaching -15F over the Berkshires where a cold
weather advisory is in effect. Elsewhere, expecting minimum wind
chills zero to -10F.
Wednesday...
Upper trough axis is over New Eng at 12z then moves to the east
thereafter. Some ocean effect clouds may linger over the outer Cape
and Nantucket, otherwise expect abundant sunshine across the region.
High clouds will be approaching from the west by late in the day.
925 mb temps around -15C again so expect highs upper teens and lower
20s. NW wind 5-15 mph will result in max wind chills in the single
numbers and teens.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Key Messages:
* After a period of chilly weather, more seasonable temperatures
return Thursday into this weekend.
* Mainly dry conditions, though will watch a weak surface low pass
offshore Thursday night/early Friday.
High pressure will be the dominant weather feature through much of
the extended forecast and the Arctic airmass exits the region, with
some improvement by Thursday. While it is "warmer" come Thursday the
temperatures are still slightly below normal highs for late January.
Highs rebound to the upper 20s and low 30s Thursday to Saturday, and
then the mid and upper 30s Sunday into Monday. Overnight lows are
still fairly chilly Thursday and Friday night in the upper single
digits and low teens, then more seasonable in the upper teens and
low 20s Saturday and Sunday night. For reference, the average high
across SNE ranges between the low 30s across the interior and upper
30s at the coast. As for the average lows, interior are generally in
the teens with the coast in the low 20s.
Mostly dry weather into the extended, through there is a wrinkle or
two to discuss. First is Thursday evening into early Friday morning
with the passage of a weak off shore low pressure system. Majority
of the guidance, GFS, GEM, and ECMWF would keep this far enough off
shore and are in agreement there would be little to no moisture to
work with, as PWATs are less than 0.2". Now, where the wrinkle comes
into play is the NAM 12Km, which brings in much higher PWATs ~0.5"
to mainly the islands, outer Cape, and the south coast. Did lean on
the NBM blend, would have the best chance of any precipitation at
Nantucket and capped POPs at 30% and the south coast at 15%. At this
point, the chance of light snow is low. Beyond this point a weak
clipper low pressure system passes to our north late Saturday night
into Sunday morning. The best forcing is displaced to our north in
northern NY & northern VT, with limited moisture yet again, would
think a few upslope snow showers are possible during this time frame
and limited POPs to northwest MA. Otherwise, mainly dry weather
through the extended.
&&
.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
18Z Update:
Through 00Z... High Confidence
VFR. West winds 5 to 10 knots. Increasing mid-level clouds
between 050-100 feet.
Tonight...High Confidence
VFR across the interior with winds becoming light out of the
west/northwest. -SN expected over The Cape/Islands terminals
with periods of MVFR ceilings and perhaps IFR vsbys, especially
at ACK. Expect snow to taper off before 12Z.
Tomorrow....High confidence.
VFR. NW wind 5-15 kt.
Tomorrow Night...High Confidence
VFR. Winds becoming light out of the west/southwest.
KBOS TAF...High Confidence in TAF.
KBDL TAF...High Confidence in TAF.
Outlook /Wednesday Night through Saturday/...
Wednesday Night: VFR.
Thursday: VFR. Breezy.
Thursday Night through Friday Night: VFR.
Saturday: VFR. Breezy.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High- greater than 60 percent.
Today through Wednesday...
Marginal SCA seas over the southern waters will subside this morning
with seas remaining mostly below SCA through the rest of the period.
W winds 10-20 kt today becoming NW-N later tonight into Wed. A few
gusts over 20 kt possible late tonight and early Wed. Arctic airmass
will result in areas of light freezing spray this morning and again
late tonight and Wed morning as winds ramp up a bit.
Outlook /Wednesday Night through Saturday/...
Wednesday Night: Winds less than 25 kt.
Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain, slight chance of snow.
Thursday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of rain, slight chance of snow.
Friday: Winds less than 25 kt. Seas locally approaching 5 ft.
Friday Night: Winds less than 25 kt.
Saturday: Winds less than 25 kt. Seas locally approaching 5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Cold Weather Advisory from midnight tonight to 10 AM EST
Wednesday for MAZ002-008-009.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...KJC/Dooley
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...Dooley
AVIATION...Dooley/RM
MARINE...KJC/Dooley
Source:
BOX issues Area Forecast Discussion (AFD) at Jan 21, 12:09 PM EST----------------
If I'm using your data in a way that is against your terms please email the team at "threatweb@pupswoof117.com"! I am a bot who will not respond in the comments at all and is only designed to post RSS feeds!
