US Day 3-7 Hazards Outlook
NWS Weather Prediction Center College Park MD
439 PM EST Wed Dec 01 2021
 
Valid Saturday December 04 2021 - Wednesday December 08 2021
 
Hazards:
- Heavy precipitation across the higher terrain of the Pacific Northwest, as well as parts of the 
northern Idaho, Mon, Dec 6.
- Heavy precipitation across portions of northwestern Washington, Wed, Dec 8.
- Heavy precipitation across portions of northwestern Wyoming, Tue, Dec 7.
- Heavy rain across portions of the interior Deep South to the southern Appalachians, Wed, Dec 8.
- Flooding occurring or imminent across portions of northwestern Washington.
- Flooding likely across portions of northwestern Washington.
- Heavy snow across portions of southwestern Alaska, Mon, Dec 6.
- High winds across portions of Seward Peninsula in Alaska, Sun, Dec 5.
- Much below normal temperatures across portions of central and eastern Alaska, Sat, Dec 4.
 
Detailed Summary:

Latest model guidance continues to advertise general troughing across the eastern two-thirds of the 
country with two low pressure systems of concern traversing through the region during the medium 
range period.  A broad ridge of high pressure initially anchored in the western U.S. will be 
progressively eroded by shortwave energies descending into the northern Rockies.  The relatively 
fast flow in this pattern continues to introduce timing issues with precipitation associated with 
the two low pressure systems.  Models and ensembles have shown better definitions for a swath of 
wintry precipitation to spread from west to east from the northern Plains through the Great Lakes 
and northern England for the weekend and into Monday.  While most of the precipitation amounts are 
just below the criteria for a hazard area, some of the wintry precipitation could be locally 
enhanced by the warm waters further downwind from the Great Lakes.  By Tuesday into Wednesday, the 
second low pressure system moving through the region appears to bring another round of wintry 
precipitation across the Great Lakes into the northern Ohio Valley and then toward northern New 
England.  No precipitation hazards were depicted in these areas yet.  However, early model signals 
suggest a heavy rain area across the interior Deep South to the southern Appalachians next 
Wednesday ahead of a strong cold front.

Meanwhile, moisture ahead of the next Pacific cyclone is forecast to reach into the Pacific 
Northwest region by Sunday night into Monday.  It appears that areas from the Cascades westward to 
the coast will be impacted by moderate to heavy precipitation during this time frame.  The higher 
elevations of the Washington Cascades will likely see snow while other areas will see rain.  Some 
of the heavier precipitation should also spread into parts of the higher elevation of northern 
Rockies.  A general decrease of precipitation amounts are expected thereafter as the system dips 
further inland through the central Rockies and the Great Basin.

Temperature-wise, widespread milder than normal conditions are expected to continue for the 
majority of the country through the middle of next week.  Below average and winter-like 
temperatures are expected to be confined to New England, where lows could dip into the teens and 
single digits beginning on Saturday.  Colder than normal weather will be ushered into only a 
limited portion of the northern Plains and the upper Midwest/Great Lakes behind the two low 
pressure systems.

Alaska will likely enter a period of increasingly active weather as the first round of snow 
associated with a series of fronts and cyclones are forecast to reach western part of the state on 
Saturday.  The bitterly cold airmass initially engulfing the interior portions of the state will 
give away to moderating temperatures as the snowy and windy weather picks up in intensity over 
southwestern Alaska on Sunday.  A foot or more of heavy snow is forecast to first impact the 
southwestern portion of the Seward Peninsula on Sunday ahead of a deep cyclone traversing the 
Bering Sea.  By Monday, heavy snow is forecast to impact portions of southwestern Alaska as the 
center of the cyclone pushes onshore.  Other areas across southwestern Alaska up to the Seward 
Peninsula will likely see moderate snowfall.  In addition to the snow, much of the region will 
likely be impacted by south to southeasterly winds 35 mph or stronger.  The snow associated with 
this system should reach the southern coast and further down along the Panhandle Tuesday and 
Wednesday.  Amounts are generally below heavy snow criteria for these areas although uncertainty 
remains high at present.

Kong