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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KBOX 250206
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1006 PM EDT Sun Mar 24 2019

.SYNOPSIS...
A cold front sweeps across the region tonight followed by cooler but
dry weather Monday. Dry weather continues through the end of the
week with chilly weather Tue gradually moderating as the week
progresses. Mild weather next weekend but risk of showers increases
Sunday as cold front approaches.

&&

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

No major changes to the forecast this evening. Mid and high
level clouds will gradually increase across southern New England
overnight, particularly along and south of the Mass Pike. Main
changes this evening were to bring temperature back in line with
observed trends. Large dewpoint depressions will continue near
the ground, for several more hours anyway. Not expecting much
precipitation to reach the ground, but cannot dismiss the
possibility of a few light showers later tonight.

Showers more likely toward the south coast of New England late
tonight, where the low level humidity is higher, and a cold
front approaches from the north. This cold front was across
central VT and NH at 10 PM, so it will take just about all night
to reach the coast. Will continue to monitor its progress.

Previous Discussion...

Mainly high clouds currently moving across SNE ahead of mid
level shortwave. Cold front moving south from northern VT will
take its time as it approaches SNE and cross SNE late tonight
and Mon morning. Moisture is limited so expecting a mainly dry
fropa. Best moisture stays to our south with marginally dry low
levels over SNE so this shortwave passage isn`t expected to
bring much more than increased cloud cover. If anything a few
light spot showers may appear Monday morning, best chance over
the Berkshires where orographics can help, and along the south
coast where higher dewpoints located. Lows only drop into the
30s given the warm airmass ahead of the front.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Cold front moves off the south coast Monday morning ushering in
a drier airmass and quickly clearing skies. Best chance of
seeing some clouds is along the south coast, closest to better
moisture and a passing system to our south. High pressure
expanding over SNE should keep this system suppressed well to
our south. CAA behind the front but the coldest air doesn`t make
it over the region until Tuesday morning, so we`ll still see
highs in the upper 40s.

Monday night north winds bring the cold pool south with 850mb
temps dropping from -5C to -12C between Monday and Tuesday
mornings. This brings lows back into the 20s; teens in the
higher terrain.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Highlights...

* Dry weather through much of the upcoming week
* Chilly Tue, then warming trend with above normal temps by Fri
* Mild and mainly dry Sat, then increasing risk of showers Sun

Tuesday through Friday...

Mainly dry weather through at least Thu and possibly into Fri as
well, but shower risk will increase slightly Thu night/Fri. Coastal
storm moves well out to sea Tue with high pres building into New Eng
Tue night/Wed leading to mostly clear skies. Mid level trough over
New Eng on Tue with 850 mb temps -10C will bring below normal temps,
then moderating Wed as trough lifts out and heights rise.

Warming trend will continue Thu and Fri as high pres moves offshore
with SW flow developing. Temps should be near normal Thu and above
normal Fri with some 60s possible across interior locations. Still
dry Thu, then northern stream trough passes to the north as weak
cold front approaches from northern New Eng. This may lead to a few
showers Thu night/Fri, mainly across the interior, but dry weather
most of the time.

Saturday and Sunday...

Forecast confidence decreases as models differ on how additional
northern stream energy dropping into the Great Lakes and New Eng
interacts with approaching Pacific shortwave. It looks like mostly
dry weather may hold on for Sat as front stalls to the north and
west with backing flow ahead of next shortwave. Just a low risk for
a few showers in western MA at this time, but this is day 6 and if
the trough and front speed up, the risk for showers will increase.
If front does remain to the north, potential for temps well into the
60s to near 70 degrees in the interior Sat.

Low confidence forecast for Sunday. GFS indicating more progressive
northern stream with cold front sweeping through Sat night with a
period of showers then cooler and drier Sun. ECMWF shows much more
amplified northern stream trying to phase with Pacific energy.
Result is much slower timing of front with mild weather lasting into
Sun although shower threat would be increasing from the west as
front approaches. 12z EPS shows considerable spread with location of
the boundary but favor a compromise between deterministic ECMWF and
GFS with fairly high probs of rainfall. As a result we will indicate
chc showers for Sun.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...

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

Short Term /through Monday Night/...

Tonight...

VFR and dry this evening with WSW winds. After 06Z, VFR cigs
OVC100 with a spot shower or sprinkle possible. WSW winds
shifting to NW.

Monday ...

Brief MVFR in the morning, mainly south coast with low risk of
a spot shower/sprinkle, then trending VFR from north to south
with dry conditions. North winds.

Monday night... VFR.

KBOS terminal...High confidence in TAF.

KBDL terminal...High confidence in TAF

Outlook /Tuesday through Friday/...

Tuesday through Wednesday: VFR. Breezy.

Wednesday Night through Thursday: VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

Short Term /through Monday Night/...

This evening, extended the Small Craft Advisory for most of the
south coastal bays and sounds. Observations continue to indicate
gusts up to 25 kt late this evening.

Tonight ...

Dry cold front moves across southern New England. WSW winds become
NW toward daybreak as cold front moves toward the south coast.

Monday ...

WSW winds becoming NNW by midday as dry cold front moves offshore.

Monday Night ...

Light N/NE winds. Seas less than 3ft becoming 3-5 ft

Outlook /Tuesday through Friday/...

Tuesday through Wednesday: Winds less than 25 kt. Areas of seas
approaching 5 ft.

Wednesday Night: Winds less than 25 kt.

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 1 AM EDT Monday for ANZ232>235-237.
     Small Craft Advisory until 6 AM EDT Monday for ANZ254>256.

&&

$$
SYNOPSIS...KJC/BW
NEAR TERM...Belk/KJC/BW
SHORT TERM...BW
LONG TERM...KJC
AVIATION...KJC/BW
MARINE...KJC/BW