Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
252 AM EDT Wed Oct 28 2020
Valid 12Z Sat Oct 31 2020 - 12Z Wed Nov 04 2020
...Overview and Guidance Evaluation/Preferences...
A progressive yet still amplified pattern is forecast for the
CONUS Sat-Wed with troughing primarily in the eastern half of the
lower 48 and ridging in the West into Texas this weekend. Through
the 12Z/18Z models, the latest guidance consensus offered a good
starting point to the forecast with the lead trough into the East
by early Mon. Thereafter, the GFS/GEFS were a bit quicker than the
ECMWF ensembles and the 12Z ECMWF even slower, but the multi-day
trend has been slower as well. Preferred to weight the ECMWF and
especially its ensemble mean more than the GEFS mean for next
Tue-Wed as the GFS appears too progressive. Canadian offered some
support to the ECMWF but became too different on timing/amplitude
(perhaps too flat) to include in the blend by the end of the
period.
...Weather/Hazard Highlights...
Troughing will carry a surface front and respectable surface low
(in Canada) through the Midwest on Sunday but with generally
little precipitation. Temperatures will cool post-FROPA and
daytime highs will be about 5-15 degrees below normal. Rain and
some high elevation snow is forecast for the Northeast and perhaps
Mid-Atlantic as the front moves through the region Sunday. Some
lake-enhanced precipitation cannot be ruled out either. Over
Florida, the tail-end of a cold/stationary front in addition to
another cold front Monday will maintain a chance of at least light
rain for central and southern Florida. More significant
precipitation may enter the Pacific Northwest midweek next week as
a front comes ashore. Temperatures will be near to above normal in
the West through the period.
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