[Weather] [2019.11.30 430PM] NWS Boston EM Briefing: Weather Hazards for Sunday thru early Tuesday

Sat Nov 30 21:54:11 UTC 2019

Good evening everyone,

Here is the latest information on the upcoming significant winter storm,
which will begin tomorrow afternoon and end early Tuesday morning.

*Watches/Warnings/Advisories:*

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

*What we expect:*

*Sunday into early Monday*

   - Snow will begin in western MA between Noon and 1 PM Sunday; CT Valley
   and central MA 1-3 PM Sunday; and eastern MA 3-5 PM.
   - Snow becomes heavy at times (1"/hour) shortly after onset and
   continues in the late afternoon and evening hours.
   - As warmer air intrudes aloft, precipitation changes to sleet, then
   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 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 about 3 PM.  It will reach RI and
   eastern MA (except Cape Cod/Islands) by between 7 PM and 11 PM Monday.  The
   snow could 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 remains 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.
   - Confidence remains low enough at this point, however, to have
   continued the Winter Storm Watch for many interior locations.  This is due
   to not being completely sure of the extent of the warm air intrusion, which
   could greatly impact snowfall totals.  A colder scenario by just a few
   degrees would mean more snow than currently forecast.  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.

Attached are wind gust, onset timing, and snow total graphics.  A more
comprehensive Powerpoint will be forthcoming soon.

-- Glenn Field/Rodney Chai
   NWS - Norton, MA

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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