Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
320 PM EST Fri Jan 28 2022
Valid 12Z Mon Jan 31 2022 - 12Z Fri Feb 04 2022
...Next week to bring heavy precipitation to the central and
eastern U.S., including winter weather from the Central Plains to
Great Lakes and interior Northeast around midweek...
...Overview...
A weak shortwave moving through the southern Plains on Monday
should generate enhanced rainfall along/north of the Texas Gulf
Coast, before shearing out pretty quickly on Tuesday due to a
building ridge over the western Atlantic. After this, troughing
will dig into the West Tuesday-Wednesday and shift/expand eastward
into the central U.S. Thursday. By Friday, broad longwave
troughing should cover much of the CONUS as strong ridging builds
over the eastern Pacific and western Atlantic. This evolution is
expected to bring widespread precipitation along a leading frontal
boundary into much of the eastern half of the country mid-late
next week, with potential for notable wintry weather on the
backside of the system.
...Guidance Evaluation/Predictability Assessment...
Recent model guidance remains in generally good agreement for the
overall large scale pattern, but with continuing uncertainty in
the smaller scale details. Models are pretty consistent with the
track of the initial compact southern stream upper low over Texas
Monday and into the Gulf early Tuesday before shearing out with
somewhat variable timing. A multi-model deterministic blend worked
well for this feature. In the northern stream, a couple of
shortwaves moving across the Great Lakes region toward the western
Atlantic early in the workweek showed good agreement in the 00Z
and 06Z GFS and 00Z ECMWF, with some slightly different solutions
in the 00Z CMC and UKMET.
Then there is good consensus with energy diving south through the
Intermountain West for the first half of the workweek, serving to
deepen the trough in the west-central U.S., but with lingering
uncertainty on the exact magnitude--the 00Z UKMET was deeper than
other guidance/most ensemble members by early Wednesday. The trend
toward less separation of streams within the trough has remained
for the past couple of cycles, so there is a building consensus
with that. Then by Thursday into Friday, there are some additional
differences with shortwave features within the broader trough.
Energy moving through the base of the trough Thursday exhibits
some differences that also affect frontal and surface low position
by Friday in the Northeast, while model guidance also varies with
strength of energy possibly dipping through the western side of
the trough. In general the GFS runs have been stronger with this
feature (with the exception of the 06Z GFS) compared to ECMWF
runs, but the 12Z ECMWF came in with a stronger shortwave than its
past runs. So the run-to-run inconsistencies as well as notable
differences in individual ensemble members show this aspect is
still uncertain.
The WPC forecast used a multi-model deterministic blend favoring
the GFS and ECMWF early in the period, gradually phasing in some
proportion of the 06Z GEFS and 00Z EC ensemble means to about 40
percent by the end of the period to maintain some definition of
systems but smooth individual model differences.
...Weather Highlights/Threats...
The upper shortwave/low into the Southern Plains by Monday will
bring a threat for locally moderate to heavy rainfall from eastern
Texas across parts of the Gulf Coast region during the first half
of next week. The best potential still appears to be over eastern
Texas, with some potential for heavy rainfall farther east along
the Gulf Coast depending on the exact track of the mid-upper
energy. The northeastern Pacific upper trough digging into the
West Monday-Tuesday will spread light to moderate amounts of lower
elevation rain and mountain snow from the Pacific Northwest
eastward and southeastward into much of the Rockies. In general,
the forecast remains on track for a significant increase of
coverage and intensity of precipitation over the east-central U.S.
the second half of the week as the upper trough emerges from the
Rockies and the leading cold front interacts with a strong low
level feed of Gulf moisture. At this time the best chance for
heaviest rainfall extends across the lower half of the Mississippi
Valley into parts of the Ohio/Tennessee Valleys to the
Appalachians and the East. Wintry weather will be possible on the
northwest side of the moisture shield, with at least some
potential for meaningful snow from central parts of the Plains and
Mississippi Valley northeastward through the Great Lakes and into
the interior Northeast. While confidence in a heavy rain area
appears better than average, details with the wintry precipitation
in the colder air may be more dependent on lower-confidence
details of ejecting shortwave energy and frontal waves.
Above average temperatures initially over the Plains on Monday
should spread eastward Tuesday-Thursday as upper ridging builds
in. Behind this, arctic high pressure dives into the Central U.S.
behind the cold front midweek, bringing chilly and much below
normal temperatures all the way from the northern Rockies/High
Plains southward into Texas. Widespread daytime highs (and
slightly less extreme overnight lows) as much as 10-20 degrees
below average are possible. Locally higher values as much as 25F
below normal are possible across the north-central U.S. The below
normal temps may moderate slightly as they shift east into the
Ohio Valley/Gulf Coast states next Friday. Much of the West Coast
states should be near normal through much of next week owing to
amplified ridging across the East Pacific.
Tate/Santorelli
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 Mid-Atlantic, the
Lower Mississippi Valley, the Central Appalachians, the Tennessee
Valley, the Great Lakes, the Middle Mississippi Valley, the
Northeast, the Southern Plains, and the Ohio Valley, Wed-Thu, Feb
2-Feb 3.
- Heavy rain across portions of the Lower Mississippi Valley and
the Southern Plains, Mon, Jan 31.
- Heavy rain across portions of the Mid-Atlantic, the Lower
Mississippi Valley, the Central Appalachians, the Tennessee
Valley, the Middle Mississippi Valley, the Northeast, the Southern
Appalachians, the Southeast, and the Ohio Valley, Wed-Thu, Feb
2-Feb 3.
- Heavy snow across portions of the Central Plains, the Northeast,
the Southern Plains, the Middle Mississippi Valley, the Upper
Mississippi Valley, the Great Lakes, and the Ohio Valley, Wed-Thu,
Feb 2-Feb 3.
- High winds across portions of the Central Rockies, the Central
Plains, and the Northern Plains, Mon, Jan 31.
- Much below normal temperatures across portions of the Central
Plains, the Central Rockies, the Lower Mississippi Valley, the
Central Great Basin, the Northern Plains, the Northern Rockies,
the Southern Rockies, the Middle Mississippi Valley, the Upper
Mississippi Valley, the Southern Plains, and the Southwest,
Wed-Fri, Feb 2-Feb 4.
- Much below normal temperatures across portions of the Lower
Mississippi Valley, the Tennessee Valley, the Great Lakes, the
Middle Mississippi Valley, the Upper Mississippi Valley, the
Southern Plains, and the Ohio Valley, Fri, Feb 4.
- Much below normal temperatures across portions of the Southeast,
Mon, Jan 31.
- Heavy precipitation across portions of the Alaska Panhandle and
mainland Alaska, Thu-Fri, Feb 3-Feb 4.
- Heavy precipitation across portions of mainland Alaska and the
Aleutians, Mon-Thu, Jan 31-Feb 3.
- High winds across portions of the Aleutians, Mon-Wed, Jan 31-Feb
2.
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