Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Wed Mar 16 2022
Valid 12Z Sat Mar 19 2022 - 12Z Wed Mar 23 2022
...Strong low pressure system will likely produce heavy rain and
severe storms across large sections of the southern U.S. toward
the Tennessee Valley by early next week...
...Overview...
A rather active weather pattern is in store for the medium-range
period as a low pressure system moving through the Northeast this
weekend will give way to a deep upper level trough forecast to
move quickly through the western U.S. This deep trough will
likely amplify as it reaches the central/southern Plains early
next week and evolves into an elongated low pressure system. A
large section of the southern U.S. to the Tennessee Valley will
likely be impacted by heavy rain and severe storms. Meanwhile on
the back side of the system, the central Rockies to the Front
Range could potentially be impacted by a winter weather event.
...Guidance Evaluation/Predictability Assessment...
Model guidance this morning appears to be in rather decent
agreement with the aforementioned synoptic evolution across the
U.S. through the medium-range period. The deterministic solutions
begin to diverge toward the middle of next week as expected but
the ensemble means still show rather decent agreement on the
position of the surface low pressure system forecast to form over
the central Plains. The GFS continues to be on the faster side of
the guidance with more aggressive downstream frontal development
toward the East Coast by midweek next week. In contrast, the
ECMWF has been slower with the progression of the trough by
digging the upper energy farther south across the Southwest and
into the southern Plains. The Canadian model has been in between
these extremes. Overall, the consensus appears to trend toward
the ECMWF's side although recent ECMWF runs have shown some more
northern stream development.
Taking these factors into account, the WPC forecast was primarily
based on the consensus of 40% 00Z ECMWF/EC mean, 40% 06Z GFS/GEFS,
and 20% 00Z CMC/CMC mean with increasing contributions from the
ensemble means toward Day 7. Overall, very good agreement with
WPC continuity was maintained for Days 3-5. A slight southward
trend on the cyclone position was noted on Day 6 , leading to a
south/eastward push of the heavy rain axis across the Mid-South.
...Weather Highlights/Threats...
The surface low tracking from the Ohio Valley to the Northeast on
Saturday will likely be accompanied by a swath of moderate to
locally heavy snow across northern portions of New England,
particularly central and northern Maine. Elsewhere, moderate rain
is expected from the northern Mid-Atlantic to central/southern New
England for the first half of the weekend.
Attention then turns to the Plains and Gulf Coast region as an
elongated surface low exiting the central/southern Rockies begins
to intensify over the central Plains by early Monday while taping
into a surge of Gulf moisture across Texas and the central Gulf
Coast region. The prospects for severe weather will expand from
eastern Texas to the central Gulf Coast states from Monday to
Tuesday whereas the heavy rainfall threat will be farther inland
from the lower to mid-Mississippi Valley northeastward to the
Tennessee Valley. Flooding rain could become an issue as multiple
rounds of convection develop over the same general areas. The
Storm Prediction Center has additional information pertaining to
the severe weather potential. On the back side of the storm, the
air mass could be cold enough to support a winter weather event
across the central Rockies into the Front Range on Monday and
possibly into Tuesday. Some wintry precipitation could also
develop over the upper Midwest/upper Great Lakes Wednesday morning
as the threat of heavy rain edges toward the Appalachians.
In terms of temperatures, the East Coast should continue to have
above normal readings this weekend and into the middle of next
week as upper level ridging develops ahead of the deep trough over
the Plains. Even greater positive anomalies are likely across the
central and northern Plains by Sunday ahead of the storm system,
with highs up to 25 degrees above average, whereas a return to
slightly below average temperatures is expected across the Rockies
and the western High Plains under the upper level trough for
Monday and Tuesday. No major surges of arctic air are expected.
Kong/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
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