[Weather] [2019.12.29 4 PM Update] NWS Boston EM Breifing: Severe Icing Threat & Wintry Mix Tonight-Monday Night

Sun Dec 29 21:22:48 UTC 2019

Good afternoon everyone,

Here is the latest information on a storm that will impact Southern New
England tonight into Tuesday. The greatest impacts are expected across the
higher elevations of the slopes of the Berkshires, northern Worcester
County and northwest Middlesex County. The graphics attached include the
Winter Storm Severity Index (gives an idea where the worst impacts can be
anticipated), storm total ice accumulations, current winter headlines,
precipitation onset time, sustained wind speeds and peak gusts tonight into
Monday afternoon (i.e. period when icing is greatest).

*What has changed:*
Winter Storm Warning changed to an Ice Storm Warning for northern Worcester
County and northwest Middlesex County. In those areas we now expect one
quarter to one half inch of ice with isolated totals to three quarters of
an inch.

*Current Watches/Warnings/Advisories in effect:*

All warnings and advisories over land are in effect from tonight through
Tuesday AM

   - *Ice Storm Warning **for the eastern slopes of the Berkshires,
   northern Worcester County and northwest Middlesex County.* Here is where
   the most significant icing is expected due to a long duration of freezing
   rain. Severe impacts can be expected with extensive power outages and tree
   damage. The Monday morning commute will be treacherous in those areas.

   - Winter Weather Advisory *for the rest of Southern New England except
   for southern RI, southern Plymouth & Bristol Counties in MA into Cape Cod
   and the Islands*. Mix of precipitation types for these areas. Expect
   lesser, but still impactful  accretions of freezing rain and sleet.  A
   slick Monday morning commute can be expected.

*Marine Watches/Warnings in effect:*

   - *Gale Warnings* for all of the coastal waters except for Narragansett
   Bay. Starting Monday morning and continuing into early Tuesday.

*Main Weather Concerns: *

1) *Severe icing across the higher elevations* *of* *western and north
central MA tonight through Monday night*. Icing begins tonight and
continues into Monday evening. For the slopes of the Berkshires we expect
to have one half to three quarters of an inch of ice with isolated amounts
up to one inch. In northern Worcester and northwest Middlesex Counties one
quarter to one half inch of ice with isolated totals to three quarters of
an inch. Easterly to northeasterly winds will increase throughout the day
with gusts of 20-30 mph in the higher terrain by late afternoon. This,
coupled with the ice, could worsen the impacts. By Tuesday temperatures
increase into the upper 30s and low 40s in the higher terrain allowing for
melting.

2)* Lower elevations: Lesser amounts of sleet and freezing rain tonight
continuing through Monday. *Accumulations of freezing rain and sleet will
impact the Monday morning commute.  Across the MA East Coast, northernmost
RI and CT a wintry mix is expected...changing to rain on Monday. Icing
amounts range from a light glaze to one quarter inch. *Localized totals may
be near a half-inch in spots northwest of I-84 and I-495 if freezing rain
can remain more prolonged*.

3)  *Strong east to northeast winds* are expected over the coastal waters
and along the South Coast Monday night. Expect gusts of 40-45 mph across
Cape Cod and the Islands Monday afternoon and evening.

*What we are uncertain about:*

*Moderate confidence:*

   - Uncertain on the duration and exact precipitation type outside of the
   Ice Storm Warning areas. If colder air lingers longer than currently
   forecast then this may result in a change to sleet and ice accumulations.
   The risk for this is highest across northeast MA, southern interior MA and
   into northern CT.
   - Monitoring the potential for higher ice accumulations across southern
   Worcester County and for extreme northwest Hartford County (Hartland).

Meteorologists: Nicole Belk, Bill Babcock, Glenn Field and Bill Leatham

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>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.massupt.org/pipermail/weather/attachments/20191229/acc18e43/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: WSSI-12292019.PNG
Type: image/png
Size: 552556 bytes
Desc: not available
URL: <http://lists.massupt.org/pipermail/weather/attachments/20191229/acc18e43/attachment-0006.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: WWA-20191229.png
Type: image/png
Size: 197049 bytes
Desc: not available
URL: <http://lists.massupt.org/pipermail/weather/attachments/20191229/acc18e43/attachment-0007.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: Onset_SFC.png
Type: image/png
Size: 130824 bytes
Desc: not available
URL: <http://lists.massupt.org/pipermail/weather/attachments/20191229/acc18e43/attachment-0008.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: StormTotalIce_SFC.png
Type: image/png
Size: 123161 bytes
Desc: not available
URL: <http://lists.massupt.org/pipermail/weather/attachments/20191229/acc18e43/attachment-0009.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: MaxWindMphISC_SFC.png
Type: image/png
Size: 142310 bytes
Desc: not available
URL: <http://lists.massupt.org/pipermail/weather/attachments/20191229/acc18e43/attachment-0010.png>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: MaxWindGustMphISC_SFC.png
Type: image/png
Size: 131371 bytes
Desc: not available
URL: <http://lists.massupt.org/pipermail/weather/attachments/20191229/acc18e43/attachment-0011.png>