BOX issues Area Forecast Discussion (AFD) at Oct 10, 3:09 AM EDT744
FXUS61 KBOX 100709
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
309 AM EDT Thu Oct 10 2024
.SYNOPSIS...
Blustery and cooler weather today behind a cold front, then a
warming trend Friday into Saturday as high pressure builds south
of New England. Low pressure approaching from the west brings
rain and unsettled weather to the region Sunday into early
Monday followed by drier and blustery conditions Monday
afternoon. Cooler fall-like air mass settles in behind the
departing low pressure system Tuesday and Wednesday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Upper level trough axis and shortwave will move east of SNE by
12z. As it crosses the Cape/Islands a few showers over the ocean
may graze the outer Cape through mid morning. Otherwise, the
trough axis will set up east of New Eng with one more shortwave
rotating around the upper low to the north but tracking mostly
to the east. While temps aloft are warming with the departing
trough, residual cold air aloft persists with 500 mb temps -20
to -22C this afternoon. The colder air aloft acting on shallow
low level moisture will result in diurnal CU developing again
although mostly sunny skies will prevail. Cooler airmass today
as 850 mb temps drop to 0 to -2C which supports highs mid 50s
to around 60, but a bit cooler higher terrain. These temps are
about 5-8 degrees below normal for this time of year. A deep and
well mixed boundary layer will promote excellent mixing with NW
winds occasionally gusting to 20-25 mph, perhaps up to 30 mph
in the interior.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/...
Tonight...
High pres over the Gt Lakes builds south to the mid Atlc region.
Given the center of the high is still well to the SW with ridge axis
to the west, there will be a modest NW breeze tonight and still
somewhat gusty along the immediate coast and Cape/Islands. Despite
clear skies tonight, the wind will limit radiational cooling a bit.
Still a chilly night but not as cold as it would be if the high pres
had moved overhead. Lows will be in the mid-upper 30s away from the
coast, and low-mid 40s closer to the coast where winds will be
stronger and more persistent. Low risk for isolated frost in some of
the interior valleys where winds are lighter, but overall not much
frost expected.
Friday...
High pres remains to the SW with dry NW flow across SNE. Abundant
sunshine expected with limited CU as temps aloft are warmer and
soundings not showing much low level moisture. Mixing depth is more
shallow but 925 mb temps warm to 10-11C so highs should reach mid-
upper 60s, but cooler higher terrain. The milder temps will be
accompanied by W-NW winds 10-20 mph.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Key Points:
* Warm and sunny Saturday
* Next chance for rain most likely in early Sun evening through
Monday time frame.
* Cooler airmass positions over the region next week bringing
slightly below normal temperatures, mainly Tuesday-Thursday.
Details:
Friday Night through Saturday Night:
Ensemble guidance shows a general consensus in a transition to a
zonal upper level pattern with WNW flow aloft by Saturday.
Conditions remain dry on Saturday despite a weak disturbance moving
through earlier on in the day. Temperatures have potential to reach
above normal values with highs in the mid 60s to low 70s. Some
models trend a bit cooler behind the early AM disturbance which
could limit those 70 degree readings. Mainly clear skies Saturday
night will promote optimal radiational cooling with lows in the
upper 30s across decent portions of interior southern New England.
Can't rule out cooler reading for the higher elevation areas. Closer
to the coast, lows drop into the low to mid 40s.
Sunday through Wednesday:
There is sufficient agreement among ensemble guidance for a
shortwave trough and accompanying surface low to lift across the
northeast over the course of Sun/Mon. There are differences in
timing being highlighted by individual ens members at this time.
Generally you can expect increasing cloud cover Sunday and rain
chances increasing throughout the course of the afternoon. This will
bring a few rounds of rain to southern New England by Monday
morning. Ensembles aren't signaling this to be an anomalous event in
regards to rainfall. Most seems to agree on amounts in the 0.1 to
0.4" range with the high end scenario (low probability) staying
less than an inch.
A deep trough across the northeast will keep anomalously cooler air
over the region Tuesday through at least Thursday. During this time
frame, expect temperatures slightly below normal in the 50s with
chillier nights dropping into the 30s. There isn't a strong signal
for precipitation during this period, but can't rule out a
few showers each day.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
06z TAF Update:
Through 12z...
SCT-BKN VFR ceilings. NW wind 5-15 kt with G20 kt
Today: High confidence.
VFR, but SCT-BKN low end VFR-MVFR cigs possible on the outer
Cape this morning. NW winds 10-15 kt with gusts 20-25 kt.
Tonight and Friday: High confidence.
VFR. NW winds diminishing to 5-10 kt tonight, but a bit stronger
Cape/Islands and immediate eastern MA coast. W-NW wind 10-20 kt
Fri.
KBOS TAF...High confidence in TAF.
KBDL TAF...High confidence in TAF.
Outlook /Friday Night through Monday/...
Friday Night through Saturday: VFR. Breezy.
Saturday Night: VFR.
Sunday: VFR. Chance SHRA.
Sunday Night: Mainly VFR, with areas MVFR possible. Breezy.
SHRA likely.
Columbus Day: Mainly VFR, with local MVFR possible. Breezy.
Chance SHRA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Today through Friday...High confidence.
Gusty NW winds with gusts to 25 kt will diminish this afternoon.
Another surge of 25+ kt gusts expected later today into this evening
for the eastern MA waters assocd with the shortwave passage to the
east. Winds diminish late tonight into Fri but still expect 10-20 kt
winds. SCA for the southern waters will drop off this afternoon, but
will continue through tonight for eastern waters for combination of
wind and building seas to 4-6 ft.
Outlook /Friday Night through Monday/...
Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft.
Saturday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft.
Saturday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft.
Sunday: Winds less than 25 kt. Chance of rain showers.
Sunday Night: Winds less than 25 kt. Local rough seas. Rain
showers likely.
Columbus Day: Winds less than 25 kt. Areas of rough seas.
Chance of rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ230.
Small Craft Advisory until 8 AM EDT Friday for ANZ231-250-251-
254-255.
Small Craft Advisory until noon EDT today for ANZ232>237-256.
&&
$$
SYNOPSIS...KJC/Mensch
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...Mensch
AVIATION...KJC/Mensch
MARINE...KJC/Mensch
Source:
BOX issues Area Forecast Discussion (AFD) at Oct 10, 3:09 AM EDT----------------
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