Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
101 AM EST Sun Jan 19 2020
Valid 12Z Wed Jan 22 2020 - 12Z Sun Jan 26 2020
...Overview...
A developing system in the Southern Plains will spread modest to
perhaps locally heavy rainfall from the Lower Mississippi Valley
northeastward next Thu-Sun. In the Pacific Northwest, a steady
stream of systems will subject some cities to some sogginess.
Overall, a warming trend over most of the CONUS is expected.
...Guidance/Predictability Assessment...
The models/ensembles were in generally good synoptic agreement in
showing a progressive and modestly amplified longwave flow
pattern. A blend among the GFS/ECMWF/Canadian formed a good
cluster around the ensemble consensus which still shows fairly
typical spread. The 12Z Canadian was mostly in between the GFS and
ECMWF and closer to the best ensemble clustering, but neither
other scenario was considered improbable. This would take the
southern system northeastward toward the Midwest with a jump
across the Appalachians through the Mid-Atlantic next weekend. Off
the West Coast, ensembles have trended toward deeper troughing
next weekend at the expense of the leading systems east of the
Rockies.
...Weather/Hazard Highlights...
Despite what is normally just about the coldest time of the year,
temperatures will trend toward above average nearly CONUS-wide by
the end of the week into next weekend. Highest anomalies will lie
astride the Canadian border with near to slightly above average
temperatures near the Gulf Coast.
Precipitation will be non-continuous but quite repetitive in the
Northwest as several systems push through. The generally mild flow
will keep snow levels a bit higher too. Farther east, rainfall
will expand over Texas to points eastward/northeastward with help
from leftover mid/high-level moisture across the eastern
Pacific/Baja Mexico. Gulf inflow will help realize modest rainfall
totals along the NW Gulf coast but with continued uncertainty to
its northward extent. Some amounts could be locally heavy. The
system will likely have some wintry weather on its northern side
from the Central Plains to the Great Lakes but with amounts
contingent on the precipitation structure and system evolution.
Fracasso
Additional 3-7 Day Hazards information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at:
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/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml