Valid Friday November 29, 2019 to Thursday December 05, 2019
US Hazards Outlook NWS Climate Prediction Center College Park MD 300 PM
EST November 21 2019
Synopsis: We expect a progressive pattern
over North America during the Week-2 period and several low pressure systems
are forecast to traverse the country leading to unsettled weather from the
Aleutians to the East Coast. There are slight chances of high winds and much
below normal temperatures throughout southern Alaska, Plains and Great Lakes.
There is also a slight chance of heavy precipitation throughout the interior
Southeast and upper Midwest, where precipitation is likely to fall as snow in
the comma head of a cyclone. There is a moderate risk of much below normal
temperatures over much of the western third of the country next weekend with
the cold air expected to spread to the East Coast by the end of Week-2.
Moderate risk of much below normal temperatures
across parts of the western CONUS, Fri-Sun, Nov 29-Dec 1.
Slight risk of much below normal temperatures across parts of southern
Alaska, Fri-Wed, Nov 29-Dec 4.
Slight risk of much below normal temperatures across most of the interior
western CONUS, Fri-Thu, Nov 29-Dec 5.
Slight risk of much below normal temperatures across much of the eastern
CONUS, Tue-Thu, Dec 3-5.
Slight risk of heavy precipitation in the upper Midwest, Sat-Sun, Nov
Slight risk of heavy precipitation in the interior Southeast, Sat-Thu, Nov
Slight risk of heavy precipitation in southern Arizona, Fri, Nov 29.
Slight risk of high winds across the Aleutians and southern Alaska,
Fri-Sat, Nov 29-30.
Slight risk of high winds across the northern and central Plains and Great
Lakes, Fri-Tue, Nov 23-Dec 3.
For Friday November 29 -
Thursday December 05: The Week-2 period is expected to feature impacts
from several mid-latitude cyclones. A series of storms in the Gulf of Alaska is
expected to produce strong winds across the Aleutians and there is a slight
risk that these winds will surpass the hazardous threshold on Nov 29-30. Much
below normal temperatures are also possible across southeastern Alaska during
the entire period, and a slight risk is also posted for Nov 29-Dec 4.
Anomalously cold temperatures are expected throughout much of the country
during Week-2. An anomalous trough is forecast to be over the western CONUS
during the first few days of the period and expand eastward throughout the
week. A slight risk (20-40%) of much below normal minimum temperatures is
posted from Nov 29-Dec 5 over the western CONUS and there is a moderate risk
(40-60%) of much below normal temperatures within that area from Nov 29-Dec 1.
Daily minimum temperatures throughout this region are expected to fall below
the 15th percentile. A slight risk of much below minimum temperatures is posted
over the eastern CONUS from Dec 3-5 as the cold air is forecast to shift
A strong mid-latitude cyclone is expected to develop late next week lee of
the Rockies and track northeastward during the forecast period. Heavy rain is
possible along the system's cold front and is likely to be concentrated in the
interior southeast. There is a slight risk of heavy precipitation in this
region Nov 30-Dec 5 as the ECMWF suggests another cyclone will impact the
Southeast near the end of the week. Rainfall amounts could exceed 1 inch per
day in this area. Heavy precipitation within the comma head of the low over the
northern Plains and parts of the upper Midwest is possible, and would most
likely fall as snow. A slight risk of heavy precipitation is posted for this
area from Nov 30-Dec 1.
High pressure is expected to develop over the western CONUS in the wake of
this cyclone and the pressure gradient between the two systems could lead to
strong winds. A slight risk of high winds is posted for Nov 29-Dec 3 over the
northern and central Plains, and the Great Lakes region. During this time,
there is a 20% chance that winds will exceed their 85th percentile values with
sustained winds > 25 mph.
Models predict a southwesterly flow of moisture into Arizona right around
the beginning of the forecast period and there is a 20% chance that rainfall in
parts of southern Arizona will exceed 1 inch on Nov 29. Localized flooding is
possible under these circumstances and interested parties should keep an eye on
the forecast from their local NWS office.
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.