WPC Medium Range Archive
Medium Range Products Valid On:
(Day 7 PMDEPD: Valid 03/30/2020 to 04/03/2020)
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
403 PM EDT Fri Mar 27 2020
Valid 12Z Mon Mar 30 2020 - 12Z Fri Apr 03 2020
...Heavy rain possible for the South Mon-Tue...
Atmospheric shuffling over North America next week has resulted in
model uncertainty and poor run-to-run continuity. The larger
anomaly centers will be across far northern Canada (70-80N) where
a closed high will move out of the North Slope eastward to the
Canadian archipelago near Resolute. The other center will be the
subtropical ridge/upper high over Florida on Monday that will
slide westward into Mexico and weaken. This generally favors
weaker troughing astride the US/Canadian border with a couple lead
impulses through the South/East.
Model guidance continues to struggle with the synoptic setup next
week across the CONUS. For the southern stream system, there is
slightly better agreement in the timing and track of an expected
area of low pressure from the south-central Plains toward the Deep
South Mon-Tue. The ECMWF low track is slightly ahead of the GFS
now, but the differences has lessened from earlier model cycle and
allowed for a near equal blend of the available deterministic
guidance for day 3-4. The system is expected to track toward the
Southeast U.S. and then off the Mid-Atlantic coast where spread
begins to increase. To maintain WPC continuity, the ECMWF and its
ensemble mean was favored for later forecast periods (day 5-7) as
the synoptic setup favors more quasi-zonal flow (an inherently
System moving out of the southern Rockies Mon will spread rain and
embedded convection across the ArkLaTex and Mid-South/TN Valley to
the southern Appalachians by Tue. Rainfall could be heavy in local
areas. Light to modest rainfall and maybe some snowfall over the
higher elevations of the Northeast will spread ENE on Wed as the
system moves out to sea. In the West, precipitation will be
heaviest early in the week with the leading stronger systems,
tapering to lighter rain/snow showers as the upper low settles
over British Columbia.
Temperatures will trend cooler in the East behind the exiting
system midweek. Some record highs may still be possible across
Florida Mon/Tue. Milder temperatures are expected over the
Southwest after Mon when the upper trough exits. Temperatures are
much more uncertain (50-60 deg spread in the guidance) over
eastern Montana to the Dakotas Tue-Thu depending on where the
frontal boundary lies. Strong high pressure (>1050mb) north of
Hudson Bay will try to funnel cold air across the border but it
will battle milder air over the central Plains.
Additional 3-7 Day Hazards information can be found on the WPC
medium range hazards chart at:
- Heavy precipitation across portions of California, the Pacific
Northwest, and the Northern Great Basin, Mon, Mar 30.
- Heavy rain across portions of the Lower/Middle Mississippi
Valley, the Tennessee Valley, the Mid-Atlantic, the Southern
Appalachians, the Southeast, the Southern Plains, and the Ohio
Valley, Mon-Tue, Mar 30-Mar 31.
- Heavy snow across portions of the Northern Plains, the Northern
Rockies, and the Northern Great Basin, Mon-Tue, Mar 30-Mar 31.
- Heavy snow across portions of the Northeast, Mon, Mar 30.
- Flooding possible across portions of the Great Lakes, the
Middle/Upper Mississippi Valley, the Southern Plains, and the
- Flooding occurring or imminent across portions of the
Middle/Lower Mississippi Valley, the Northern Plains, the
Tennessee Valley, the Southeast, the Southern Plains, and the Ohio
- Flooding likely across portions of the Middle Mississippi
Valley, the Upper Mississippi Valley, and the Northern Plains.
- Much above normal temperatures across portions of the Upper
Mississippi Valley and the Northern Plains, Mon, Mar 30.
- Much above normal temperatures across portions of the Southeast,
Mon-Tue, Mar 30-Mar 31.
- Enhanced wildfire risk across portions of the the Southern
Plains, Mon, Mar 30.
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at: