Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
157 AM EST Wed Jan 22 2020
Valid 12Z Sat Jan 25 2020 - 12Z Wed Jan 29 2020
...Overview...
A frontal boundary will lift through the Northeast this weekend
with inland and elevation snow and coastal rain. The West will
continue to see nearly daily chances of rains/snow as the pattern
remains active out of the Pacific. By next Tue/Wed, a system may
organize over the southern Plains with more rain and northern-side
snow for middle of the CONUS.
...Guidance/Predictability Assessment...
Overall a multi-model deterministic blend served as a good
starting point for the first half of the forecast period. The
eastern system has shown good run-to-run continuity with a slight
trend quicker. Much more uncertainty lies off the Pacific
Northwest coast with the flow over the northeast Pacific Ocean,
drive by a strong jet in between subtropical ridging northeast of
Hawai'i and an upper low over Alaska. This leads to lower than
average confidence in timing as the models keep shifting the
system progression with each run. Thus, a consensus blend was used
to mitigate future changes. By next Tue/Wed, trough in the West
should dig into the southern Plains and help spur cyclogenesis
along the Red River (TX/OK border). GFS/GEFS were a bit quicker
than the ECMWF/ECMWF ensembles, but a middle ground solution was
prudent for now with the large lead-in uncertainty.
...Weather/Hazard Highlights...
Two areas of low pressure will consolidate into one near Long
Island/Southern New England by Sunday morning, with snow over
inland areas/higher elevations and rain along the I-95 corridor
south of Maine. Modest to perhaps significant snow is possible for
some areas.
Given the active pattern in the West, rounds of precipitation will
continue. Higher elevations can expect snow with lower elevation
rain, with several inches liquid equivalent over the multi-day
period. Frontal system on Sun-Tue will spread precipitation
through much of the interior and central Rockies but this should
be on the lighter side overall.
Most of the CONUS will see near or above average temperatures in
the medium range, with the highest anomalies of 10 to 25 degrees
across the north-central tier of the US. Near to slightly below
average temperatures are favored across portions of the
Southeast/Florida.
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