295
FXUS02 KWBC 081842
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
142 PM EST Wed Jan 8 2025

Valid 12Z Sat Jan 11 2025 - 12Z Wed Jan 15 2025

...Overview...

A quieter weather pattern is on tap for the weekend into early next
week. Broad mean upper troughing will extend from the Northeast to
the Southwest, and a series of upper lows will churn over
southeastern Canada, the Great Lakes, and the far Northeast. A few
weak frontal system are forecast to move across the eastern two
thirds of the nation, but precipitation chances will be fairly
limited. This weekend, precipitation chances will focus over the
northern Rockies and Plains in the vicinity of low pressure and
along the East Coast as a storm system pushes offshore. Early next
week, precipitation chances will be limited to the Great Lakes
where light to moderate lake effect snows will be possible. This
pattern will continue below normal temperatures for most of the
nation, with hazardous cold for some.


...Guidance/Predictability Assessment...

Model and ensemble forecast spread continues to decrease, leading
to higher forecast confidence. The most uncertain features in the
forecast are weaker features early-mid next week, which are harder
for the models to resolve. However, the affect on the sensible
weather should be minimal since these features are not forecast to
produce significant weather hazards.

WPC`s afternoon forecast was derived from a general blend of the
available model guidance including the GFS/ECMWF/CMC/UKMET and
National Blend of Models, which produced a reasonably good
forecast given little model spread. Ensemble means from the
GEFS/ECENS/CMCE were added to the blend early-mid next week to help
smooth out minor differences in the deterministic model guidance.


...Weather/Hazards Highlights...

The winter storm set to slam the southern U.S. late this week will
be moving offshore by Saturday. Wintry weather will linger across
the Mid-Atlantic and Northeast on Saturday as the system
strengthens offshore, and light to moderate wintry precipitation
could create locally hazardous conditions, especially where snow
may be enhanced in the central/northern Appalachians and downwind
of the eastern Great Lakes. An anomalously cold air mass will
remain in place over the South, Southeast, and Mid-Atlantic through
the weekend, and trailing fronts may continue to focus periodic
rain/convection back across Florida, the northern Gulf of Mexico,
and southern Texas through early-mid next week.

Wintry weather is also expected from the Northwest to the Plains
this weekend as a frontal system tracks east. This system will
push towards the Midwest and Great Lakes early next week, likely
triggering additional lake effect snows. In the wake of this
system, another blast of Arctic air is forecast to spill into the
north-central U.S. this weekend and spread to the East and
Southeast next week. Hazardous cold temperatures are expected from
the northern Plains to the Gulf and Southeast Coasts, with
temperature anomalies potentially reaching 10-20 degrees below
normal.

Elsewhere, high pressure will dominate in the West early next week
and spread across the South by mid-week. Temperatures underneath
this area of high pressure will likely be near to slightly below
normal.


Dolan


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw




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