Valid Thursday February 11, 2016 to Monday February 22, 2016
US Hazards Outlook
NWS Climate Prediction Center College Park MD
EST February 08 2016Synopsis
: A strong area of upper-level low
pressure is expected to remain over the eastern U.S. through the next week.
Arctic surface high pressure is forecast to shift south from Canada this
weekend. The well-established area of upper-level high pressure across the
western U.S. is expected to remain strong through Thursday and then gradually
weaken when a low pressure system moves inland from the Pacific. An area of
upper-level low pressure is forecast to persist across the Aleutians during the
next two weeks. Hazards
Detailed Summary For Thursday
February 11 - Monday February 15:
- Locally heavy, lake-effect snow
downwind of the Great Lakes, Fri, Feb 12.
- Heavy snow for parts of the central and southern Appalachians, Fri, Feb 12.
- Much below-normal temperatures for the eastern U.S., Thu-Mon, Feb 11-15.
- Much below-normal temperatures for the upper Mississippi Valley, Great
Lakes, and Midwest, Fri-Sat, Feb 12-13.
- Flooding occurring or likely across parts of the Southeast and lower
- Severe Drought across parts of the western U.S. and Puerto Rico.
A highly amplified upper-level trough
across eastern North America is likely to result in a 1044-hpa surface high
shifting south from Canada into the eastern U.S. this weekend. Deterministic 6Z
GFS and 0Z ECMWF model runs are in good agreement that 850-hpa temperatures
below -24 degrees C shift from the Great Lakes on Friday to the mid-Atlantic
this weekend. The most extreme anomalous cold across the upper Mississippi
Valley, Great Lakes, and Midwest is forecast on Saturday morning when minimum
temperatures of 0 to -20 degrees F can be expected. On Sunday morning, subzero
minimum temperatures are forecast across the Northeast with single digits above
zero across the mid-Atlantic. These minimum temperatures are 20 to 25 degrees F
below-normal for mid-February. Although wind speeds are likely to remain below
hazards criteria, gusty winds of 15 to 25 mph this weekend are likely to create
dangerous wind chill values across the Northeast and mid-Atlantic. Preceding
this arctic outbreak, much-below normal temperatures (negative anomalies of
more than 12 degrees F) are also expected to prevail across parts of the
eastern U.S. on Thursday and Friday.
On Friday, strong cold air advection is expected to promote locally heavy
lake-effect snow (6 inches or more in 24 hours) downwind of the Great Lakes.
Also, heavy snow (near 4 inches) is expected across parts of the central and
southern Appalachians due to strong cold air advection coupled with upslope
flow. The deterministic 0Z ECMWF model indicates that the amplifying trough
promotes surface low development across the mid-Atlantic on Friday night. This
low pressure system poses a risk of moderate to heavy snow from the
mid-Atlantic north to New England. However, the deterministic 6Z/12Z GFS and
0Z/12Z Canadian models favor offshore development of this surface low with
little or no snow across the mid-Atlantic and Northeast. Due to these large
model differences, a heavy snow hazard is not depicted on the map for these
areas at this time.
The upper-level ridge over western North America is forecast to weaken and
allow the return of onshore flow to the Pacific Northwest later in the week.
Precipitation amounts are not expected to reach hazards criteria across coastal
Washington on Friday and Saturday.
Heavy rainfall during the past few weeks triggered minor to moderate
flooding along the following rivers: Altamaha and Savannah Rivers in Georgia,
Cape Fear River in North Carolina, Edisto River in South Carolina,
Choctawhatchee River in the Florida Panhandle, and Pearl River in Mississippi.
A persistent area of low pressure and onshore flow are expected to bring
periods of increased winds and precipitation to coastal southern Alaska and the
Alaska Panhandle during this period. However, hazardous precipitation amounts
and wind speeds are not forecast across these areas. For Tuesday February 16 - Monday
The 0Z/6Z GFS ensemble mean maintains a longwave pattern
featuring an upper-level ridge (trough) over western (eastern) North America
during Week-2. However, large spread exists among the 0Z Canadian and 0Z ECMWF
ensemble members across North America with these model solutions suggesting
more zonal flow. Model guidance indicates the potential for an impactful winter
weather event across the eastern U.S. early in Week-2. However, due to large
model spread, no hazards are designated on the map at this time.
According to the U.S. Drought Monitor valid on February 2, the coverage of
severe to exceptional (D2-D4) drought across the 50 U.S. states and Puerto Rico
decreased slightly from 7.13 percent to 7.06 percent. Severe to exceptional
drought is limited to the western third of the contiguous U.S. and Puerto
Forecaster: Brad Pugh
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.