Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
144 AM EST Mon Nov 02 2020
Valid 12Z Thu Nov 05 2020 - 12Z Mon Nov 09 2020
...Tropical Storm Eta to track slowly through the Caribbean...
...Heavy rain is possible over southern Florida...
...Heavy precipitation for the Pacific Northwest and wintry
weather through the West/Rockies/Northern Plains...
...Overview...
The large-scale upper pattern in the medium range starts with
generally zonal flow over much of the lower 48 with several
embedded progressive shortwaves. The pattern is expected to become
more amplified later week as a potent trough digs into the West,
moving slowly eastward and deepening over the weekend, spreading
precipitation to much of the West and west-central U.S..
Meanwhile, Tropical Storm Eta is forecast to move west across the
Caribbean making landfall in Central America. It remains to be
seen if energy from this system may be lifted north and east late
in the week, potentially leading to additional tropical
development, but regardless, a good amount of rain can be expected
over parts of the Florida peninsula through next weekend as
easterly flow persists north of a frontal system.
...Guidance Evaluation/Preferences...
The WPC medium range product suite was primarily derived from a
blend of the quite similar 12/00 UTC ECMWF and 12/00 UTC ECMWF
ensemble mean. Most guidance similarly agrees to amplify the
pattern
over the CONUS later week, but the ECMWF and ECMWF ensemble mean
depict tropical features closer to NHC than the more aggressive
northward motion of recent GFS/GEFS runs.
...Weather/Hazard Highlights...
The Pacific Northwest should see a wet mid-late week period given
moist inflow and a series of frontal passages, especially across
the Cascades and Olympics. As the potent trough (mid-level heights
2+ standard deviations below normal) moves into the West, snow
levels are expected to lower late week as precipitation and cooler
than normal temperatures overspread much of the Great Basin,
Rockies then northern Plains by the weekend. Ahead of this
cooldown, warmer than normal temperatures will spread from the
western/central CONUS toward the East under a building ridge
aloft. Elsewhere, heavy rainfall is possible across southern
Florida as moisture interacts with easterly post-frontal flow well
to the north of Eta and any possible additional tropical
development.
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