Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1047 AM EST Wed Mar 06 2019
Valid 12Z Sat Mar 09 2019 - 12Z Wed Mar 13 2019
...Weather Pattern Overview...
A stormy weather pattern persists through medium range time scales
as two large scale mid-upper level troughs/height falls
originating from the Pacific lead to deep surface low development
over the central U.S. and Midwest states. The first storm system
develops and intensifies across the central plains and Upper
Midwest this weekend as surface high pressure erodes the East. A
second Pacific storm crosses the Desert Southwest Tue, with
Plains/Midwest storm genesis by Wed.
...Guidance and Uncertainty Assessement...
Model and ensemble forecast clustering is quite good for much of
the forecast period with a more amplified pattern in place and
forecast predictability remains above average. The GFS,FV3,ECMWF,
Canadian and the GEFS/NAEFS/ECMWF ensemble means indicate rather
impressive consensus into day 6/Tue and a composite solution seems
reasonable. Timing issues are evident with the second main system
energing from the Southwest into the Plains/Midwest in about a
week. Prefer a slightly less progressive than concensus solution
given flow amplitude, more in line with recent ECMWF/Canadian and
ECMWF/NAEFS ensemble means. This solution maintains good WPC
continuity. However, the more progressive GFS/GEFS solutions are
plausible given potential kicker upstream shortwave approach Day 7
to the Pacific Northwest that could act to decrease system
wavelength spacing.
...Weather Highlights and Hazards...
Widespread rain and thunderstorms are expected to develop from the
Gulf Coast to the Ohio Valley and southern Appalachians on
Saturday and into early Sunday as a rich supply of Gulf moisture
surges northward ahead of a strong cold front from the Midwest
surface low. The heaviest rainfall is likely from eastern Texas to
the southern Appalachians, where a general 1 to 2 inches of rain
is likely that may lead to some local flooding issues based on the
current forecast. However, the progressive nature of the event
would limit the duration of the heaviest rain. Depending on where
the surface low tracks, a corridor of blizzard conditions is
becoming increasingly likely across parts of the Upper Midwest,
including parts of the Dakotas. Another facet to this low pressure
system will be the potential for severe thunderstorms to develop
in the warm sector, and this is something that the Storm
Prediction Center is currently monitoring.
Upstream, the pattern again favors an amplified mid-upper level
trough developing off the West Coast this weekend. This will
support another round of precipitation over the southwestern U.S.
as the trough moves inland on Monday. Additional widespread rain
may then develop across the central and southern Plains through
the Mississippi Valley/Midwest in about a week as the trough
induces another deepening surface low/storm east of the Rockies.
There is also the potential for severe weather with this storm
system, and details on this will become more evident in the
upcoming days.
D. Hamrick/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