NWS Technical Forecast Discussion


Observed at
Lowell, Massachusetts
13-Nov-2018 11:40 PM

Temperature

38.1°F

Hour Change

-2.0°F

Humidity

55%

Hour Change

-18%

Dewpoint

23.4°F

Hour Change

-8.8°F

Wind

9 mph from 315° (NW)

Wind Gust

20 mph

Barometer

29.967 inHg

3 Hour Trend

0.114 inHg

Today's Rain

1.36 in

Rain Rate

0.00 in/hr

Rain Last Hour

0.00 in

Monthly Rain

5.23 in

Yearly Rain

40.94 in

Wind Chill

31.8°F

Heat Index

38.1°F

Est. Cumulus Base

3523 feet

Today Highs / Lows

High Temperature

Low Temperature

48.9°F at 10:00 AM

38.1°F at 11:38 PM

High Humidity

Low Humidity

97% at 08:40 AM

55% at 11:35 PM

High Dewpoint

Low Dewpoint

48.1°F at 10:00 AM

23.4°F at 11:38 PM

High Barometer

Low Barometer

30.329 inHg at 12:00 AM

29.705 inHg at 02:02 PM

High Wind Gust

20 mph from 313° at 05:19 PM

High Rain Rate

0.45 in/hr at 11:16 AM

Low Wind Chill

28.1°F at 11:37 PM

High Heat Index

48.9°F at 10:00 AM

Yesterday's Statistics

High Temperature

Low Temperature

48.4°F at 01:47 PM

26.8°F at 05:17 AM

High Humidity

Low Humidity

84% at 07:51 AM

42% at 01:49 PM

High Dewpoint

Low Dewpoint

33.1°F at 11:51 PM

20.8°F at 12:02 AM

High Barometer

Low Barometer

30.436 inHg at 09:21 AM

30.325 inHg at 11:53 PM

High Wind Gust

13 mph from 229° at 11:49 AM

Rain

0.00 in

High Rain Rate

0.00 in/hr at 12:00 AM

Low Wind Chill

26.8°F at 05:17 AM

High Heat Index

48.4°F at 01:47 PM

000
FXUS61 KBOX 140253
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
953 PM EST Tue Nov 13 2018

.SYNOPSIS...
Low pressure moves off through the Maritimes as a broad
northwest surface flow brings colder air to New England. High
pressure builds over our region Wednesday and remains into
Thursday. The high drifts north during Thursday as the next low
pressure system approaches from the south late in the day. A
wintry mix will be possible with this storm Thursday night into
Friday. A weak system may bring scattered snow showers Sunday
night into Monday.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...

Northern stream trough moves across Canada tonight and
eventually turns the upper flow more northwest. The northwest
flow will bring colder air across Southern New England
overnight. This cold air advection should maintain low level
mixing, bringing gusts of 20 kts to the surface over CT and
bring gusts to 30 kt over northern border areas of
Massachusetts, especially Northeast Mass.

Satellite images show a broad area of mid and high clouds moving
over the region for part of the night. Drier air brough south in
the developing northwest flow will thin the clouds overnight,
with guidance suggesting clearing by morning.

Observed temps at 9 PM were 3-4F milder than forecast values. We
nudged hourly and overnight min temps up 1-2F in response to
this. Overall range of forecast continues to be mid 20s to
lower 30s. We are maintaining wind gusts at 20-30 kt/25-35 mph
through the night.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
Some of the coldest air of the season will be moving into the
region Wednesday and Wednesday night as arctic air flows into
the region behind the upper trough. With the upper trough axis
to the northeast and with increasing subsidence the area is
expected to remain nearly cloud free Wednesday and Wednesday
night. Cold advection will continue Wednesday and will be
weakening after 15Z. Thus mixing will become more limited. Winds
and gusts are expected to remain below advisory levels. Even if
mixed to the top of the layer winds will be briefly near
advisory levels Wednesday morning.

With the center of the high nearly overhead winds will decouple
and become light, allowing for good radiational cooling.

&&

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

*  Low pressure late Thu into Fri with rain/snow/sleet possible
*  Another weak system may bring snow showers Sun night/Mon

Details...

Thursday and Friday...

As the high crosses northern New England Thursday, winds shift
around to E-SE during the day. Clouds will push in from S-N
during the day, and will steadily lower and thicken especially
across S coastal areas. With the souther periphery of the high
in place, will be tough to get the leading edge of moisture
working into the region until Thu night. Might see some some
light rain push into the S coast toward sunset. Cold air remains
in place, with temps only reaching the 30s, except the lower
40s along the S coast.

The H5 cutoff low slowly moves E-NE across the mid Atlc states
Thu night but, as the high to the NE slowly moving to the
Maritimes, increasing easterly flow will help feed in moisture
which should allow precip to spread across the region. Big
question will be PTYPEs as the onset of the precip. Have a mixed
bag of precip moving in even along the coast to start, but
should change over to rain with a slow temp rise with the
onshore flow off the milder waters. Timing of the changeover,
and exact amounts of snow/sleet are still up in the air. Temps
inland may fall back to the 20s Thu evening, especially across
the higher inland terrain, but should start to rise after
midnight as E winds increase. Temps should rise above freezing
across most areas during Fri, but again questions whether the
cold air will scour out of the interior valleys and the higher
terrain. Something to monitor closely.

Strong low level jet moving toward S coastal areas, Cape Cod and
the islands after midnight Thu night through Fri. Could see
E-SE wind gusts up to 35-40 kt, highest across the islands
Friday morning, possibly to midday. May need wind headlines for
a time there.

Expect the surface low to cross close to or across Cape Cod or
S coastal Mass around midday Friday, then should exit rather
quickly across the Gulf of Maine. However, precip may linger
through the day, though should start tapering off late Fri
afternoon across western areas.

Friday night through Monday...

Any leftover precip across central and eastern areas should end
Fri evening. Otherwise, a nearly zonal fast flow aloft will
bring quickly improving conditions across the region. Lows Fri
night will run close to seasonal normals, in the upper 20s and
30s, except 35-40 along the coast. Winds shift to W-NW with
gusts up to 25-30 kt across Cape Cod and the islands early, but
should diminish.

Will see somewhat milder temps as compared to the previous few
days on Saturday, but will still run around 5 degrees below
normal. Another short wave approaches from the W, but should be
mainly dry as it moves across the region late Sat or Sat night.
However, this should bring another shot of colder air across
the region by Sunday with highs only in the 30s well inland to
40-45 along the coastal plain.

Another short wave may work E Sun night into Mon as a mid level
trough starts to dig across the Great Lakes. With temps falling
back to the 20s to around 30 Sunday night, may see snow showers
move across with this weak, fast moving system. May see
leftover snow showers early Mon, then conditions should improve,
though it will remain cold.

&&

.AVIATION /03Z WEDNESDAY 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/...

Overnight...High confidence.

Cloud bases have lifted to VFR all areas, and with drying at the
lower levels we expect conditions to remain VFR through the
night. Low level mixing will continue overnight, maintaining
Northwest gusts of 20-30 kts, strongest over higher terrain and
near the coast.

Wednesday...High confidence.

VFR. Gusty northwest winds. Gusts 25 to 35 kt, with some
occasional gusts to 40 kt possible.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Thursday through Sunday/...

Wednesday Night: VFR. Breezy.

Thursday: Mainly VFR, with local MVFR possible.

Thursday Night: Mainly MVFR, with local IFR possible. Windy
with gusts to 35 kt. PL and/or RA likely, chance SN.

Friday: Mainly MVFR, with local IFR possible. Windy with gusts
to 35 kt. RA likely, FZRA likely.

Friday Night: Mainly VFR, with local MVFR possible. Windy with
local gusts to 30 kt.

Saturday: VFR. Breezy.

&&

.MARINE...

Gale force gusts will continue across most of the forecast
waters through Wednesday, especially the outer waters by
Wednesday afternoon. Gale warnings continue through Wednesday
most waters. A Small Craft Advisory continues for Narragansett
Bay.

Outlook /Thursday through Sunday/...

Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas.

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain.

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

Friday: Low risk for gale force winds with gusts up to 40 kt.
Rough seas up to 14 ft. Chance of rain.

Friday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 14 ft. Slight chance of
rain showers.

Saturday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Local rough seas.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Warning until 5 PM EST Wednesday for ANZ232>234-256.
     Gale Warning from 1 AM to 3 PM EST Wednesday for ANZ230.
     Gale Warning until 7 PM EST Wednesday for ANZ231-250-251-254-
     255.
     Small Craft Advisory until 5 PM EST Wednesday for ANZ236.
     Gale Warning until 3 PM EST Wednesday for ANZ235-237.

&&

$$
SYNOPSIS...WTB
NEAR TERM...WTB/KJC
SHORT TERM...
LONG TERM...
AVIATION...WTB/KJC
MARINE...WTB

NWS BOX Office Area Forecast Discussion