Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
425 PM EDT Tue Mar 22 2022
Valid 12Z Fri Mar 25 2022 - 12Z Tue Mar 29 2022
...Overview...
An amplified upper level pattern is expected to prevail through
the medium range period as a ridge begins to build over the
western U.S. while a broad trough in the eastern U.S. will be
reinforced and possibly amplified by intrusions of colder air from
central/eastern Canada. A general cooling and drying trend is
expected across the Northeast as potentially record-setting warmth
in the West spreads eastward into the High Plains by early next
week. The most uncertain aspect in the pattern will likely be off
the West Coast where the timing and amplitude of a trough or
potentially closed low will affect when and if any significant
precipitation will move onshore for early next week. Despite the
uncertain timing of the West Coast trough, model ensemble means
indicate decent agreement for a surface low pressure system to
develop in the central Plains by next Tuesday.
...Guidance Evaluation/Predictability Assessment...
Model guidance this morning begins with generally good agreement
on slowly pulling out the low pressure system off New England on
Friday and into the weekend. Meanwhile, a clipper system is
forecast to move across the northern Plains and interact with the
departing low pressure system over new England. Models continue
to indicate some difficulties in timing this interaction,
resulting in uncertainty on the subsequent details of the trough
amplification as well as the positions of surface fronts over the
eastern U.S. There is some potential for modest cyclogenesis to
occur just off the New England coast by about Sunday.
Over the western U.S., models are in general agreement with a
ridge building across the region. In contrast, much uncertainty
lies off the West Coast where an upper trough is forecast to
amplify. Models show considerable uncertainty on the subsequent
evolution of this trough. The GFS and CMC maintain that this
feature will move into the western U.S. early next week. The
recent couple of runs of ECMWF, however, have abandoned this
scenario by closing off this trough and digs it southward well off
the West Coast. This scenario is possible given the increasingly
high amplitude nature of the pattern by the weekend.
Nevertheless, the 00Z EC mean appears at odds with the EC
deterministic by forming a low pressure system over central Plains
next Tuesday in agreement with the GFS and CMC, which would imply
a faster progression of the trough through the western U.S.
Thus the WPC medium-range package was based on the consensus of
the 00Z ECMWF/EC mean and the 06Z GFS/GEFS mean, with
increasing usage of the ensemble means by Day 5. A small
contribution of the 00Z CMC was included for Days 3-4 followed by
a small amount from the CMC mean Days 5-7. The results are
reasonably compatible with WPC continuity except the timing of low
pressure waves off the West Coast.
...Weather Highlights/Threats...
Snow is forecast to linger in Maine on Friday as a low pressure
center slowly exits New England. Then shortwave energy and weak
low pressure/frontal systems are expected to produce light
precipitation as they move across the Great Lakes region to the
central/northern Appalachians and Northeast late week into the
weekend. Some of the precipitation will be in the form of snow in
higher elevations and near the Canadian border followed by strong
and gusty winds with falling temperatures. Precipitation ahead of
the approaching eastern Pacific upper trough is likely to reach
the Pacific Northwest around Friday. Most of this activity should
be in the light to moderate range but some locally heavier totals
are possible. By early next week, precipitation associated with
an upper trough could move into the western or southwestern U.S.
but with uncertain timing and intensity of system details.
Unseasonably warm temperatures will build and expand underneath
upper ridging from the western U.S. into the Plains. Highs that
are 10-20F above normal will be common over California and the
Great Basin/Southwest Friday, with some plus 20-25F anomalies
appearing in the Great Basin Saturday and moving to the
northern/central High Plains early next week as the upper ridge
axis shifts east. Daily record temperatures could be tied or set
across California and eastward. Temperatures in the West are
likely to cool closer to normal by around Monday but the exact
timing will depend on the trough's movement inland. Meanwhile the
East should see near to slightly below average temperatures given
mean upper troughing, with coolest temperatures of 10-15F below
normal in the central Appalachians for the weekend and in the
Great Lakes early next week.
Kong/Tate
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
Hazards:
- Heavy precipitation across portions of the Central Great Basin,
California, and the Southwest, Sun-Mon, Mar 27-Mar 28.
- Flooding possible across portions of the Lower Mississippi
Valley, the Southern Plains, the Upper Mississippi Valley, the
Northern Plains, and the Tennessee Valley.
- Flooding likely across portions of the Middle Mississippi
Valley, the Upper Mississippi Valley, and the Northern Plains.
- High winds across portions of the Upper Mississippi Valley and
the Northern Plains, Fri, Mar 25.
- Much above normal temperatures across portions of the Central
Great Basin, California, and the Southwest, Fri-Sat, Mar 25-Mar 26.
- Much above normal temperatures across portions of the Central
Rockies, the Central Plains, the Southern Plains, and the Northern
Plains, Sun-Mon, Mar 27-Mar 28.
- Heavy precipitation across portions of mainland Alaska, Fri, Mar
25.
- Heavy precipitation across portions of the Alaska Panhandle,
Mon-Tue, Mar 28-Mar 29.
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