Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
238 AM EDT Mon Oct 21 2019
Valid 12Z Thu Oct 24 2019 - 12Z Mon Oct 28 2019
...Guidance/Uncertainty Assessment and Weather
Highlights/Threats...
Guidance agrees that the active flow pattern will reload over the
cooling/unsettled West Wed/Thu as digging upper impulse/jet
energies support some enhanced Rockies snows. Height falls should
then act to carve out an amplified central U.S. upper trough later
week. Pattern evolution uncertainty grows quickly, resulting in
low forecast confidence. Guidance continues to indicate two
possible scenarios by this weekend: (1) A more amplified upper
trough draws in deep moisture from the Gulf and results in a low
pressure system that spreads heavy rainfall well inland, as
indicated by recent ECMWF/UKMET and CMC solutions; or (2) less
flow separation between the northern and southern streams will
keep a cold front moving steadily across the southern and eastern
U.S., as indicated by recent GFS runs. GEFS/EC/CMC ensembles are
mixed, with ECMWF ensembles showing the most support for the first
scenario. WPC progs modestly lean the forecast to show such
potential. This considers upstream upper ridge amplitude and as
the next main upper trough does not bring renewed cooling with
enhanced precipitation/mountain snows through the Northwest then
Rockies until next weekend, so wavelength spacing with the
downstream system seems sufficient to allow for at least some
southern stream separation.
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