[Weather] [2019.12.01 530 AM] NWS Boston EM Briefing: Weather Hazards for Sunday thru early Tuesday

Sun Dec 1 10:20:07 UTC 2019

Good morning everyone,

Here are our latest thoughts on the upcoming significant winter storm
impacting southern New England this afternoon through early Tuesday.

*Watches/Warnings/Advisories:*

1) NEW: Winter Storm Warning now includes Western Hampden, Western
Hampshire, all of Franklin, northern Worcester, and northern/central
Middlesex counties in MA.
2) NEW: Winter Weather Advisory now includes Hartford, Tolland, and Windham
counties in CT; northwest Providence County in RI; Norfolk, eastern
Hampden, eastern Hampshire, southern Worcester, Suffolk, southeast
Middlesex, and Essex counties in MA.
3) NEW:  Gale Warning now in effect for all coastal waters from this
afternoon through Monday afternoon/night.

*What we expect:*

Changes: Slightly lower snowfall totals from our last update and slower
onset time today.

*Sunday into early Monday*

   - Slower onset. Snow will begin in western MA between 2 and 3 PM Sunday;
   CT Valley and central MA 3-4 PM Sunday; and eastern MA 4-6 PM.
   - Snow becomes heavy at times (1"/hour) shortly after onset and
   continues into the evening hours.
   - As warmer air intrudes aloft, precipitation changes to sleet and
   freezing rain in northern CT, RI, to a sleet/snow mix in northern MA, and
   to plain rain in southern RI and southeast MA for the overnight hours.
   - By daybreak Monday, snow/sleet accumulations of 6-8" possible in
   western and northern MA with approximately 4-6" in Springfield and interior
   Essex County, with 2-5" elsewhere, except less than an inch on Cape
   Cod/Islands and near the immediate coast in southeast MA and southern RI.
   - The snow will be very moisture-laden.  This could make for compact
   snow but it will be heavy to shovel.
   - Wind gusts will increase to 25-40 mph along the south coast late
   Sunday night.

*Monday into early Tuesday*

   - Early in the morning, rain will be occurring in RI, portions of
   northern CT and much of eastern MA, with a mixed bag elsewhere.  However,
   everything will change back to snow from west to east. The changeover will
   reach as far east as northeast MA, central MA, and northern CT by early to
   mid afternoon.  It will reach RI and eastern MA (except Cape Cod/Islands)
   by mid afternoon into the late evening. The snow will likely continue into
   early Tuesday morning.  Less snow is expected than what occurred on the
   front end Sunday, but there still could be several inches in some
   locations.  This may be dependent on where localized bands of heavier snow
   set up.
   - Winds will gust to 35-45 mph along coastal areas, with the highest
   gusts over Cape Ann, outer Cape Cod, and the coastal waters off eastern MA.
   - Storm surges of up to 2 feet are expected, but due to low astronomical
   tides, only splashover is expected for east coastal MA, including Cape Cod
   Bay and Nantucket (with northeast winds).  Will keep a close eye on this as
   some pockets on minor coastal flooding cannot be ruled out.

*Storm Total Accumulations:*

   - We are still expecting a widespread 8 to 10 inches over much of
   interior MA with as much as a foot possible in the higher Worcester hills
   and 12 to 17 inches in the east slopes of the Berkshires.  Amounts drop off
   rapidly as one heads southeast, with 3 to 5 inches from southern Hartford
   County eastward to Providence and Plymouth and less than an inch on Cape
   Cod and the Islands.

*Confidence* :

   - Confidence is highest in the warning areas of western and northern MA,
   where >6" of snow in a 12 hour period or 8" in a 24 hour period is likely.
   - Our lowest confidence is in southeast sections, particularly along the
   I-95 corridor.  This could be a situation in which there is a sharp
   snowfall gradient within the city of Boston,  with only a slushy inch or
   two at the immediate coast to warning criteria amounts in western Suffolk
   County.

-- Matt Belk/Bryce Williams

If you have any questions or would like more information, don't hesitate to
contact us via this email address, on NWSChat <https://nwschat.weather.gov/>,
or at the following:

National Weather Service Boston/Norton, MA
46 Commerce Way
Norton, MA 02766
508.622.3280
Website <http://www.weather.gov/boston> | Facebook
<http://www.facebook.com/NWSBoston> | Twitter
<http://www.twitter.com/NWSBoston>
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