Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
224 PM EDT Thu Oct 29 2020
Valid 12Z Sun Nov 01 2020 - 12Z Thu Nov 05 2020
...Overview...
In the wake of an anomalously strong upper trough moving through
the northeastern CONUS early in the medium range period, primarily
fast zonal flow set ups across the CONUS next week. Aside from a
few weather system impacting the Pacific Northwest, much of the
lower 48 will see little in the way of precipitation. Temperatures
will initially start off below normal for the eastern U.S. then
moderate while the western U.S. stays mostly above normal.
...Guidance Evaluation/Preferences...
The large scale upper pattern exhibited average to above average
forecast confidence and run to run consistency such that high
weights of the deterministic runs of the GFS/ECMWF/CMC/UKMET were
utilized for day 3-5. Beyond that time frame, the typical fast
bias of the GFS was noted and this led to decreasing use of its
deterministic run for day 5-7 while the GEFS was supported more.
The ECENS was the favored mean late in the forecast period and
offered a good blend staying close to continuity.
...Weather/Hazard Highlights...
The respectable cold front in the Midwest early Sun will sweep
through the East Coast later in the day, ushering in the coldest
air of the season to some areas of the Mid-Atlantic as well as
some strong/high winds to portions of the Northeast and New
England. Morning lows on Monday may flirt with freezing toward the
I-95 corridor with highs only in the 40s through Virginia.
Temperatures will moderate Tuesday onward as heights rise and NW
winds turn to W and SW by mid week. In the West, temperatures will
be about 5-15 degrees above normal to start the period, spreading
eastward into the Plains by Tuesday and Great Lakes/Northeast
Wednesday/Thursday. The greatest precipitation totals across the
CONUS will be found across the Pacific NW, particularly Washington
State where a series of atmospheric river events will bring
unsettled weather. In the wake of the strong cold front early next
week, lake effect snows will be possible downwind of Lake Erie and
Ontario.
Taylor
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