NWS Forecast Area Discussion - New England Area

000
FXUS61 KBOX 162005
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
405 PM EDT Tue Oct 16 2018

.SYNOPSIS...
A cold front moves through the region Wednesday followed by the
coldest air of this young fall season invades Wednesday night
and Thursday. However the cold weather is short lived with
moderating temps Fri and Sat but a chance of showers ahead of a
cold front Saturday. Colder air returns Sunday and Monday behind
the frontal passage.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Clear skies will prevail tonight, with some increase in mid/high
clouds late tonight across western New Eng as mid level trough
moves into the Gt Lakes. Enough gradient tonight will maintain
modest wind over the higher terrain and coastal areas which will
limit radiational cooling. Lows will range from the mid 30s to
lower 40s.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Wednesday...

Robust mid level trough and shortwave moves into New Eng with
attending cold front sweeping across the region during the
afternoon. Steep low level lapse rates approach dry adiabatic
in the 0-3km layer which will lead to broken clouds developing
given some low and mid level moisture. Can`t rule out a few
showers, especially interior given modest forcing but overall
moisture is a limiting factor and will limit areal coverage.
Gusty SW winds in the morning will shift to W in the afternoon
with gusts to 25-35 mph developing in the cold advection
pattern. Moderating low level temps will lead to a miler day
with highs into the lower 60s in the coastal plain with mid 50s
over the interior higher terrain.

Wednesday night...

Strong cold advection will bring anomalous cold airmass for
this time of year with gusty W/NW winds. -10C air at 850 mb
moves into SNE by 12z Thu. Lows will range from the upper 20s
higher terrain to low/mid 30s elsewhere away from the outer
Cape/Islands. Wind chills late Wed night into Thu morning will
drop to the upper teens to mid 20s. No frost expected given wind
and very dry air, but freeze headlines likely needed for
portions of the interior where growing season is still active.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Highlights...

* Brief surge of winter cold Thursday
* Moderating temperatures Friday and Saturday
* Return to colder than normal Sun & continuing into early next week
* Mainly dry this period with just scattered showers Fri ngt/Sat

Synoptic Overview and Model Preferences.

GEFS and ECENS continue to support a persistent eastern Pacific
trough/western Canada ridge this period which fits teleconnections
of a -EPO and + PNA. This favors downstream trough over eastern
Canada into New England. Given the NAO remains positive the flow
remains somewhat progressive so these cold surges will be short
lived. However central-northern Atlantic ridge coupled with the
western Canadian ridge will support eastern Canadian/New England
trough to reload resulting in temperatures at or colder than normal
much of this period.

Thursday...

High amplitude mid level trough over the Maritimes advects a winter-
like airmass into New England with 850 mb temps down to -10C to -8C.
This will only support highs in the 40s which is about 15-18 degs
colder than normal! These highs are more typical of early Dec, thus
running way ahead of schedule. It will feel even colder courtesy of
NW winds gusting up to 20-30 mph which will yield wind chills in the
30s. So definitely a winter chill in the air Thu. Wed night will be
the colder night for the urban areas given the strong CAA however
Thu night will be colder for the suburbs. This will be a result of a
very dry airmass with dew pts in the teens combines with diminishing
wind and mostly clear skies. Leaned toward the colder MOS guidance
here with lows in the 20s across many of the suburbs and 30-35 in
the cities including much of the immediate coastline.

Friday...

Upper air pattern remains progressive so anomalous cold trough exits
with rising heights/warming temps aloft offering a nice rebound in
temperatures.  In addition anticyclonic mid level flow and
associated subsidence should yield mostly sunny conditions.
Increasing southwest winds will erode/modify leftover cold air with
925 mb temps recovering to about +5C by Fri afternoon, supporting
highs well into the 50s.

Weekend...

WAA pattern ahead of next northern stream trough and attending cold
front. 925 mb temps warm to about +9C Sat afternoon so highs in the
lower 60s seem reasonable. Thus leaned toward the warmer EC MOS for
highs. Models have trended a bit faster with this short
wave/attending front with greatest risk for scattered showers Fri
night into Sat morning with possible drying trend Sat afternoon
given quicker FROPA.

Post frontal airmass overspreads the area Sat night into Sun. Cold
cyclonic flow aloft will yield diurnal clouds and perhaps a spot
rain/snow shower especially over the interior. Otherwise dry weather
prevails. However it will be cold with 12z ECENS 850 mb temps
ranging from -4C to -6C, supporting highs from the upper 40s to
lower 50s. It will feel colder given blustery NW winds. This will be
followed by another chilly night (Sunday night) as winds diminish
and lows dip into the 20s and 30s.

Early next week...

Persistent long wave trough hangs tough over eastern Canada into New
England with colder than normal temps Monday with highs only in the
40s. Some moderation Tue ahead of next short wave and attending cold
front, however looks like this just reloads the long wave trough
with a reinforcing surge of cold air for mid week. Mainly dry this
period other than low risk of scattered showers with short wave and
attending cold front around Tue.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...

Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

Short Term /through Wednesday Night/...High confidence.

Through tonight...VFR. Light W/SW wind.

Wednesday...
VFR. sct-bkn cu 5-6k ft developing in the afternoon, greatest
coverage in the interior where a few showers possible. Gusty SW
winds in the morning becoming west with 25-30 kt gusts
developing in the afternoon.

Wednesday night...
VFR. W/NW gusts 20-30 kt early in the evening, then
diminishing but remaining gusty along the immediate coast.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Thursday through Sunday/...Moderate-High confidence.

Thursday: VFR. Windy with gusts to 35 kt.

Thursday Night: VFR. Windy with local gusts to 30 kt.

Friday: VFR. Breezy.

Friday Night: Mainly VFR, with areas MVFR possible. Windy with
areas gusts to 30 kt. Chance SHRA.

Saturday: Mainly MVFR, with areas VFR possible. Windy with
gusts to 30 kt. Chance SHRA.

Saturday Night through Sunday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

Short Term /through Wednesday Night/...High confidence.

West winds mostly below SCA tonight. Increasing SW winds
Wednesday morning, then gale force west wind gusts developing
Wed afternoon and continuing through Wed night in strong cold
advection behind the cold front. Gusts to 35-40 kt expected.

Outlook /Thursday through Sunday/...Moderate to High

Thursday: Low risk for gale force winds with gusts up to 35 kt.
Areas of rough seas.

Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Local rough seas.

Friday: Winds less than 25 kt. Areas of seas approaching 5 ft.

Friday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Chance of rain showers.

Saturday: Low risk for gale force winds with gusts up to 35 kt.
Areas of rough seas. Chance of rain showers.

Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Areas of rough seas. Slight chance of
rain showers.

Sunday: Moderate risk for Small Craft Advisory winds with gusts
up to 25 kt. Areas of rough seas.

&&

.CLIMATE...
Record Low Maximum Temperatures for Thursday October 18

BOS   45 in 1898
ORH   36 in 1989
BDL   44 in 2009
PVD   46 in 1939

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Warning from 2 PM Wednesday to 8 AM EDT Thursday for
     ANZ232>235-237-254>256.
     Gale Warning from 4 PM Wednesday to 4 AM EDT Thursday for
     ANZ230.
     Gale Warning from 4 PM Wednesday to 8 AM EDT Thursday for
     ANZ231-250-251.
     Small Craft Advisory from 10 AM Wednesday to 8 AM EDT Thursday
     for ANZ236.

&&

$$
SYNOPSIS...KJC/Nocera
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...Nocera
AVIATION...KJC/Nocera
MARINE...KJC/Nocera
CLIMATE...

NWS BOX Office Area Forecast Discussion