Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
159 AM EST Wed Nov 06 2019
Valid 12Z Sat Nov 09 2019 - 12Z Wed Nov 13 2019
...Central/Eastern U.S Winterization includes Northern Tier to
Northeast Snows...
...Pattern Overview and Guidance/Predictability Assessment...
The larger scale flow pattern is expected to remain amplified this
weekend into next midweek and feature aloft a U.S. West Coast to
Alaska ridge and downstream trough over the central/eastern CONUS.
Overall, forecast confidence in the large scale pattern is above
average, and a favored blend of the latest GFS/ECMWF, GEFS/ECMWF
ensemble means and NBM provides a good starting point for the Day
3-7 product suite.
...Weather Highlights/Threats...
To the west of the Rockies expect mainly warm and dry conditions.
One exception may be with some modest Pacific
moisture/precipitation that may work into the West Coast mean
upper ridge position, especially into favored terrain of the
Pacific Northwest.
The downstream pattern under a mean upper trough laden with
embedded shortwave impulses favors periodic reinforcement of
colder than normal temperatures from the Rockies and Central U.S.
to the East as post-frontal surface high pressure centers track
south/southeast from Canada. A lead airmass will cross the
central/eastern states by Sat with a fairly broad coverage of
temperatures 10-20F below normal that could produce a few record
cold values. Then by Sun-Wed an even colder surge with highs
15-25F below normal is expected to spread across the central and
eastern U.S. that may produce more widespread record cold
temperatures.
A lead weekend clipper system and trailing cold cyclonic flow will
bring mostly snow to the Great Lakes/Northeast with snows
prolonged into next week by lake effect. Meanwhile, locations
along the eastern slopes of the northern-central Rockies will see
periods of enhanced snows as the trailing Arctic front digs
southward. The longwave upper flow pattern then suggests potential
for coastal low development offshore the East Coast early-mid next
week, although there is considerable uncertainty in its coastal
proximity and extent of potential wintery impacts. Guidance trends
show increased support for another threat of some heavy snow for
the Northeast and vicinity.
Schichtel
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