Valid Monday, November 24, 2014 to Friday, December 05, 2014
Summary of Forecasts and Hazards
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EST November 21 2014Synopsis
: A strong storm system is predicted
to reach the Great Lakes by Monday. Surface high pressure is anticipated to
build across much of the rest of the lower 48 states during the first half of
the period. A cold front is forecast to sink southward from Canada by
Wednesday, bringing cold, arctic air to northern portions of the eastern and
central Contiguous U.S. Another cold, surface high is predicted to spread
southward from Canada during the beginning and middle of week-2. A series of
surface lows are anticipated to develop over the Bering Sea, Aleutians, and
Gulf of Alaska during days 3-7. Hazards
Detailed Summary For Monday November
24 - Friday November 28:
- Localized heavy
lake effect snow for parts of Michigan and Wisconsin, Mon-Wed, Nov 24-26.
- Localized heavy lake effect snow for parts of the Lower Great Lakes,
Tue-Wed, Nov 25-26.
- Possible localized flooding for parts of the Great Lakes, Mon, Nov 24.
- High winds for parts of the Upper Mississippi Valley and Great Lakes,
Mon-Tue, Nov 24-25.
- Much below normal temperatures for parts of the Northern Plains, Upper
Mississippi Valley, and Upper Great Lakes, Wed-Fri, Nov 26-28.
- Heavy snow for parts of the Cascade Mountains, Mon-Tue, Nov 24-25.
- Heavy snow for parts of the Northern and Central Rockies and Northern and
Central Great Basin, Mon-Wed, Nov 24-26.
- Much below normal temperatures for parts of the Central Rockies, Mon-Tue,
- Slight chance for much below normal daily minimum temperatures across much
of the central and eastern Northern Tier of the CONUS, Sat-Mon, Nov 29-Dec 1.
- Severe drought for the Central and Southern Great Plains, Southwest,
Southeast, Tennessee Valley, Pacific Northwest, Great Basin, and California.
A strong storm system is predicted to reach the
Great Lakes at the beginning of the period, bringing localized heavy lake
effect snow to parts of Michigan and Wisconsin, Monday to Tuesday and the Lower
Great Lakes on Tuesday. This storm may also bring high winds to parts of the
Upper Mississippi Valley and Great Lakes Monday to Tuesday, with sustained wind
speeds possibly reaching 30-40 knots or greater. As this storm exits the U.S.
into Canada, a surface low is expected to develop over the Upper Great Lakes
along a cold front draped across the Northern Tier on Wednesday, leading to
enhanced chances for another bout of lake effect snow across parts of these
Great Lakes areas on Wednesday. The greatest likelihood for significant
snowfall is over Michigan and Wisconsin, with the potential for half an inch of
liquid equivalent or greater in a 24-hour period. Currently, lower snow
accumulations are expected for areas east of Lakes Erie and Ontario. This cold
front is anticipated to move southward across the central and eastern CONUS,
bringing much below normal temperatures to parts of the Northern Plains, Upper
Mississippi Valley, and Upper Great Lakes, Wednesday to Friday. These areas may
experience daily temperatures 16 degrees or greater below normal, with minimum
temperatures reaching the negative single digits in some locations.
A moderation of temperatures is anticipated for parts of the Great Lakes on
Monday. Above freezing temperatures, in addition to expected rain showers, may
lead to localized flooding of creeks and lakes from melting of antecedent Lake
Effect snow in the Great Lakes region on Monday. The greatest chances for
significant flooding are east of Lakes Erie and Ontario. Urban sections of
Buffalo may experience ponding and flooding due to the large volume of melt
water overloading drainage systems. The area south of Lake Michigan is expected
to have minor flooding. The aforementioned cold front sinking southward from
Canada is anticipated to provide flood relief in these areas by Tuesday due to
the expectation that temperatures will go below freezing.
A series of surface lows are expected to develop over the northeast Pacific
Ocean. Strong onshore flow associated with this pattern is anticipated to bring
localized heavy snow to parts of the Cascade Mountains Monday to Tuesday. This
area may receive an inch or greater of liquid equivalent in a 24-hour period.
In general, snow elevation levels are expected to rise to between 7000 to 8000
feet by Tuesday, with the exception of snow levels potentially remaining at
3000 feet near the Canadian border.
Surface high pressure is forecast to build across the western half of the
CONUS during this period, leading to strong, upslope flow across the Rockies
for much of this period. This pattern is expected to bring episodes of
localized heavy snow to higher elevation areas of the Northern and Central
Rockies and Northern and Central Great Basin Monday to Wednesday. Some areas
may receive an inch of liquid equivalent or greater in a 24-hour period. This
northwesterly, upslope flow is also expected to bring much below normal
temperatures to parts of the Central Rockies on Monday and Tuesday. Daily
minimum temperatures may reach the negative single digits in some
For Saturday November 29 - Friday December 05:
There is much more
consensus amongst models today compared to yesterday, regarding the potential
for another surge of cold, arctic air from Canada into northern parts of the
CONUS from the beginning to middle of week-2. An area for slight risk of much
below normal temperatures is highlighted across much of the central and eastern
Northern Tier of the CONUS next Saturday to the following Monday. These areas
may experience daily minimum temperatures below the 10th percentile compared to
In general, a relatively zonal pattern is predicted for week-2, favoring
above-normal temperatures for much of the western two-thirds of the CONUS, and
normal temperatures for the eastern third of the CONUS, excluding the area of
below normal temperatures across the Great Lakes mentioned above. Normal to
above normal 500-hPa heights are forecast for Alaska, bringing normal to above
normal temperatures to the state.
The most recent U.S. drought monitor, released on November 20, indicates a
slight decrease in the areal coverage of severe to exceptional drought (D2 to
D4) from 17.27 percent to 17.13 percent across the Continental
Forecaster: Melissa Ou
Click here to see a display of the GFS Ensemble Forecasts
Please consult local NWS Forecast Offices for short range forecasts and region-specific information.