NWS Forecaster Discussion
BOX
Area Forecast Discussion National Weather Service Boston/Norton MA.
201
FXUS61 KBOX 240217
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
1017 PM EDT Wed Oct 23 2019
.SYNOPSIS...
Dry and pleasant weather continues into the first half of Friday.
A cold front sweeps through with a few showers Friday night, then
high pressure will bring dry and seasonably cool weather Saturday.
Rain is expected Sunday as low pressure approaches from the Ohio
Valley and crosses southern New England. A few showers may linger
early next week as a front remains near our area.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
1017 PM Update...
No significant changes to the ongoing forecast. Brought the
forecast back in line with observed trends. Relatively quiet
and dry weather will continue overnight.
Previous Discussion...
Daytime cumulus clouds have dissipated, and clear skies will be
the rule overnight. The slightly gusty west/northwest winds are
also fading away with the loss of heating and resulting
atmospheric mixing. Still enough of a pressure gradient that a
light wind will continue all night in most areas. The air is
rather dry (dewpoints mostly in the 30s) so temperatures should
fall pretty fast the rest of the evening. Forecast for lows in
the 30s to lower 40s looks good (warmer along the Cape and
across the Islands). Some of those normally chilly places could
drop to the lower/mid 30s, but not looking at any significant
frost threat. We shouldn`t see any fog either thanks to a slight
breeze and dry low levels. Have a good night.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Thursday...
High pressure in control will result in dry and pleasant
weather. Highs Thu afternoon should recover well into the 60s
with plenty of sunshine. A little breezy by Thu afternoon, but
a very nice afternoon for late October standards with
temperatures averaging a bit above normal.
Thursday night...
High pressure centered to our south will result in another
dry/tranquil night of weather. Model cross sections indicate
some mid/high level cloudiness may impact the area times with
the focus north of the MA Turnpike. This should not have a big
impact on overnight temps. Overnight low temps will mainly be
in the upper 30s to the middle 40s in most locations.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Highlights...
* Few showers late Friday into Saturday then dry/cool.
* Soaking rain Sunday.
* Mainly dry/seasonable next week but a few showers possible.
Subtropical ridge breaks down as we head into weekend which allows
southern stream closed low over southern Plains to eject NE into
Great Lakes. Early next week a decent shot of cold drops into
northern Plains as full-latitude trough takes up residence over
central part of country. Eventually trough begins to lift out toward
Northeast during middle of next week which should lead to period of
below average temperatures.
Looking at day to day weather, a fast moving front crosses SNE
Friday night into early Saturday morning under rather zonal flow
aloft. Moisture isn`t overly impressive so we`re only expecting a
few showers, especially across northern MA. High pressure follows
with dry but seasonable day Saturday with highs in 50s.
Low pressure lifting from Ohio Valley into eastern Great Lakes will
bring widespread soaking rainfall Sunday as secondary low develops
over mid Atlantic and probably tracks through SNE. Ensemble SA
tables aren`t off the charts with this system but do show potential
for strong moisture transport as PWAT anomalies reach +2 to +3 SD.
This setup with low level SE flow often keeps higher rainfall totals
west of SNE but we should still see widespread 0.50 to 1.00" amounts.
Certainly looks like a chilly and wet day with highs in upper 40s to
mid 50s.
More uncertainty as we head into new work week. Overall pattern
looks dry but models/ensembles diverge a bit with 12Z GFS quicker to
eject northern stream trough into Northeast, which drives another
surface low into eastern Great Lakes and returns wet weather to our
region. For now we will ride with model blend and have some mention
of showers but confidence is pretty low this far out in time.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Thursday Night/...
What you see is pretty much what we will continue to see for the
next 24 hours. VFR conditions area wide the entire time. Surface
W/NW winds overnight should remain 10 kt or less. Surface winds
turn more SW on Thursday, with gusts around 20 kt again expected
from mid-day through the afternoon.
KBOS Terminal...High confidence in TAF.
KBDL Terminal...High confidence in TAF.
Outlook /Friday through Monday/...
Moderate confidence through the period.
Thursday Night: VFR. Breezy.
Friday through Friday Night: VFR. Slight chance SHRA.
Saturday: VFR.
Saturday Night: Mainly VFR, with local MVFR possible. Breezy.
Chance RA.
Sunday: Mainly MVFR, with areas IFR possible. Breezy. RA
likely.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Thursday Night/...
Tonight...High confidence. SCA conditions for mainly seas will
persist on the outer-waters for much of tonight, but a gradual
downward trend is expected as high pressure builds in from the
southwest.
Thursday and Thursday night...High confidence. High pressure
centered to our south will result in some 20 to perhaps 25 knot
wind gusts at times across our northern waters. Will continue
SCA into the first half of Thu evening across our northern
waters for marginal wind gusts/seas. Across the rest of our
waters, expect winds and seas to remain below SCA thresholds.
Outlook /Friday through Monday/...Moderate confidence to
Friday: Winds less than 25 kt.
Friday Night: Winds less than 25 kt. Slight chance of rain
showers.
Saturday: Winds less than 25 kt.
Saturday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Rain likely.
Sunday: Moderate risk for Small Craft Advisory winds with gusts
up to 25 kt. Rough seas up to 9 ft. Rain likely.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 11 PM EDT Thursday for ANZ250.
Small Craft Advisory until noon EDT Thursday for ANZ251-254.
Small Craft Advisory until 6 AM EDT Thursday for ANZ255-256.
&&
$$
SYNOPSIS...Frank/JWD
NEAR TERM...Belk/Nash
SHORT TERM...Frank
LONG TERM...JWD
AVIATION...Nash
MARINE...Frank/JWD