Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
246 PM EDT Mon Mar 30 2020
Valid 12Z Thu Apr 02 2020 - 12Z Mon Apr 06 2020
...Guidance/Predictability Assessment...
The WPC medium range product suite was primarily derived from a
blend of compatable guidance from the 06 UTC GFS and 00 UTC
ECMWF/ECMWF ensemble mean days 3-5/Thu-Sat. This solution offers
good WPC continuity and average predictability. Later, the models
seem to have been having a more difficult time than usual recently
at longer time frames due to pattern sensitivty upstream and/or
data injest issues TBD. I asked for EMC/MEG to look into it as the
GEFS and especially the GFS are again showing some big run-run
continuity changes by day 6/7. The ECMWF/CMC are not immune to
this issue either, especially inland from the Pacific.
Accordingly, WPC Day 6/7 products gravitated to the ECMWF ensemble
mean in a pattern with below normal predictability.
...Weather/Hazard Highlights...
Precipitation will focus along/ahead of a shortwave lifting over
the north-central U.S. Thu-Fri along the track of frontal low
pressure from Kansas to Minnesota. Marginally cold air digging on
the northwest side of the low offers a heavy snow risk, especially
from the central Rockies through the Dakotas. Precipitation will
become lighter farther east over the Great Lakes/Northeast this
weekend as upper ridging only slowly relents.
Underneath, a series of hard to time southern stream impulses will
eject over TX and the lower MS Valley/central Gulf Coast states
and combine with frontal/moisture convergence to produce a
periodic local threat for heavy rains Thu-Mon.
Meanwhile, the Pac NW will see some light rain/snow as a couple
systems move through, but there is some signal for organized
activity through CA and to a lesser extent the Intermountain West
this weekend into early next week. The Sierra may have the most
threat for heavy snow with this series of systems.
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