Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
252 AM EDT Fri Mar 26 2021
Valid 12Z Mon Mar 29 2021 - 12Z Fri Apr 02 2021
...Overall Weather Pattern...
The overall mid-upper level pattern across the continental U.S. is
expected to be rather amplified next week. The departing
trough/cold front off the East Coast Monday will allow for an
upper ridge to briefly build with an embedded southern stream
disturbance tracking across the southeastern U.S. through
Wednesday. Meanwhile, the next major storm system will be in
place over the Rockies and Intermountain West to begin the week,
and this storm system will steadily across the central and eastern
U.S., reaching the East Coast around Thursday. A large surface
high should settle in across the Plains and Midwest for the end of
the week.
...Model Guidance and Predictability...
The deterministic model guidance indicates above average agreement
on the main synoptic scale features, particularly across the
northern half of the U.S., through Wednesday evening. The 00Z CMC
becomes slower with the next storm system approaching the Pacific
Northwest for the end of the week, and it's farther west with the
downstream upper ridge axis across western Canada. The 00Z UKMET
is faster with the arrival of the western U.S. trough across the
High Plains by midweek and ahead of the model consensus, and
similar to its 12Z run.
A southern stream shortwave over the southern Plains Monday
continues to show some uncertainty regarding timing, and potential
interaction with the larger scale trough to the west, as it
crosses the southeastern U.S. The GFS is weaker overall than the
other deterministic guidance and currently not the favored
solution for this region. The WPC medium range product suite was
primarily derived from a composite blend of the 12Z ECMWF/CMC/some
GFS/UKMET for the Monday through Wednesday time period, and then
less of the CMC for Thursday and Friday owing to the slower
solution across the West. This maintains good WPC product
continuity from the previous forecast cycle.
...Sensible weather and potential hazards...
The strong East Coast storm system will be exiting the Northeast
Monday morning, with strong and gusty winds and colder weather in
its wake, and some snow showers for northern New England. The
next system crosses the Intermountain West with a strong surface
low trekking across southern Canada for the beginning of the week.
This will bring another round of rain and mountain snow to the
central and northern Rockies through Tuesday. As the cold front
reaches the Central U.S. by Monday/Tuesday, it should advect
enough Gulf moisture northward to produce showers and storms from
Texas to the Deep South, and locally heavy rainfall is possible
across the Appalachians by mid-week, although models differ on the
axis of heaviest rainfall. Strong winds are also expected across
the northern Plains and Upper Midwest through Tuesday owing to the
strong pressure gradient that will be in place.
Temperatures are expected to be well above average ahead of the
cold front advancing across the Plains, especially on Monday when
highs could be pushing 70 degrees as far north as the Canadian
border. An abrupt return to reality ensues by the middle of the
week as a much colder airmass advects into the region behind the
front, with readings about 5-15 degrees below average. The good
news is the cold weather should be relatively brief as highs
return to above average levels by Friday ahead of the next storm
system, whereas readings are considerably colder for the East
Coast states by then as a Canadian surface highs builds into the
region.
Hamrick
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook 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