BOX issues Area Forecast Discussion (AFD) at Oct 23, 10:05 PM EDT180
FXUS61 KBOX 240205
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
1005 PM EDT Wed Oct 23 2024
.SYNOPSIS...
A weak cold front arrives late tonight and could bring a few
brief showers, followed by somewhat cooler conditions Thursday
but still above normal. Generally dry and pleasant weather is
on tap for Friday and Saturday with a brief shot of chilly
temperatures Sunday into Monday behind a cold frontal passage.
High pressure then shifts east of the region early next week
allowing unseasonably warm temperatures to return Wednesday and
especially by Thursday. The extended period of dry weather also
looks to continue well into next week with just a low risk for a
few brief scattered showers on Saturday.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Made some tweaks to rainfall chances this evening based on the
last few runs of the HRRR, which appeared to be handling the
band of showers across NY state pretty well. Clouds expected to
arrive overnight. Low level dew points surged upward this
evening, increasing the risk for rainfall to reach the ground.
Still not very confident in measurable amounts, but did
increase PoPs for portions of the western half of southern New
England.
Minor tweaks to temperatures as well.
7 PM Update...
Upper trough approaches from the Gt Lakes tonight with the
accompanying cold front moving across SNE 06-12z. This is a
sharp trough axis with a narrow band of 1"+ PWATs moving across
the region ahead of the trough. However, much of the global
guidance is pretty muted with QPF and suggest a mostly dry
fropa as the column does not fully saturate. That being
said...based on latest radar trends and the last few runs of the
HRRR opted to include the risk for brief isolated showers
overnight. Clouds will be increasing ahead of the front and pre-
frontal SW flow will result in milder temps with lows mainly in
the 50s.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Thursday...
The upper trough axis moves through during Thu with closed low
possibly developing south of New Eng. This will slow the
eastward progression of the front but not until it moves off the
coast by 12z. A few morning showers will be possible with the
trough passage, mainly near the south coast. Drier air will
gradually move in from west to east with any lingering morning
clouds giving way to increasing sunshine. Airmass not all that
cool behind the front with 925 mb temps 8-12C so while it will
be cooler, temps will still be above normal with highs mid-upper
60s, cooler interior high terrain. Becoming breezy behind the
front with soundings supporting N-NW gusts to 20-25 mph, perhaps
up to 30 mph for the Cape and Islands.
Thursday night...
Upper trough moves offshore with rising heights and surface high
pres gradually building in from the west. Expect clear skies
with diminishing wind, especially interior but winds will stay
somewhat gusty along SE coastal MA and Cape/Islands. Coolest
temps in the low- mid 30s will be in western MA where best
radiational cooling, with mildest temps mid-upper 40s
Cape/Islands. Low temps mostly upper 30s and lower 40s
elsewhere.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Key Points...
* Extended period of dry/tranquil weather continues into next
week
* Low risk for brief scattered showers Sat...but may remain dry
* Pleasant Fri/Sat with a brief shot of chilly air Sun into Mon
* Unseasonably warm temps return Wed & especially Thu...record
highs?
Details...
Dry and tranquil weather will continue through much of next
week. A ridge of high pressure builds into the region Fri and
slides to our east Sat as a cold front approaches. There is the
low risk for a brief round of scattered showers Sat...but model
guidance currently does not show any QPF as the front is
moisture starved. We can not rule out that the models begin to
indicate a bit better chance for a few showers as we get closer
to Sat...but either way not expecting much if anything. Main
impact with the front will be a shot of chilly air Sun into Mon.
Highs should mainly be in the 60s Fri & Sat...but more like 50s
Sun. Mon should be the chilliest day with the chilly start and
high pressure overhead limiting mixing. Highs Mon likely remain
in the 40s in parts of the high terrain and struggle to get too
much passed 50 elsewhere. It will be quite chilly Sun
night...when many locales may drop well down into the 20s to the
lower 30s as high pressure builds over the region.
This high pressure system will slide east of the region by Tue
and Wed. This will allow a return southwest flow of much
milder air back into the region Wed and especially by Thu. The
EPS/GEFS anomalous upper level ridging setting up across the
mid-Atlantic coast. Southwest flow should allow highs to
probably reach back into the 70s by Wed and perhaps taking a run
at 80 by Thu. Still quite a ways out...but certainly may
challenge a few record highs given strong support from the
EPS/GEFS guidance.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
00z TAF Update...
Tonight and Thursday...Moderate confidence.
Mainly VFR conditions...but may see enough marginal moisture
return to result in a period of MVFR to even localized IFR
conditions towards the south coast, Cape and Islands overnight.
But thinking it does not make it much further north than that.
SW winds shift to NW 06-12z behind a cold front with gusts to
20 kt developing during Thu. Gusts to 25 kt possible
Cape/Islands. Nothing more than an isolated brief shower or
two with the cold front...but it mainly moves across the region
dry.
Thursday night...High confidence.
VFR. Diminishing wind, but gusts to 20 kt Cape/Islands.
KBOS TAF...Moderate confidence. Some risk for MVFR cigs
developing tonight but just included SCT035 layer in the TAF
for now as confidence was not high enough. Thinking main risk is
south of the terminal.
KBDL TAF...High confidence.
Outlook /Thursday Night through Sunday/
Friday: VFR. Breezy.
Friday Night: VFR.
Saturday through Sunday Night: VFR. Breezy.
Monday: VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
High confidence through the end of this week.
Another round of gusty NNW winds to 25 kt will develop over
eastern MA waters during Thu afternoon and evening. Small Craft
Advisories have been re-issued for this time period. We also
hoisted Small Craft Headlines later Thu into Fri for the outer-
waters...where seas are also expected to build to 5+ feet.
Outlook /Friday through Monday/...
Friday: Winds less than 25 kt. Local rough seas.
Friday Night through Saturday: Winds less than 25 kt. Areas of
seas approaching 5 ft.
Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Seas up to 5 ft.
Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft.
Sunday Night: Winds less than 25 kt. Areas of seas approaching
5 ft.
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
&&
.FIRE WEATHER...
For Thursday, expecting minimum relative humidity values of 35
to 45 percent are expected. N to NW winds will gusts to 20 to
25 mph. Based on input from our area Fire Weather Partners...a
Special Weather Statement will be issued to highlight the
elevated fire weather concerns.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from noon to 7 PM EDT Thursday for
ANZ231>234-251.
Small Craft Advisory from noon Thursday to 8 PM EDT Friday for
ANZ250-254-255.
Small Craft Advisory from noon Thursday to 2 PM EDT Friday for
ANZ256.
&&
$$
SYNOPSIS...KJC/Frank
NEAR TERM...Belk/KJC/Frank
SHORT TERM...KJC
LONG TERM...Frank
AVIATION...KJC/Frank
MARINE...KJC/Frank
FIRE WEATHER...Staff
Source:
BOX issues Area Forecast Discussion (AFD) at Oct 23, 10:05 PM EDT----------------
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