Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
202 AM EST Fri Jan 28 2022
Valid 12Z Mon Jan 31 2022 - 12Z Fri Feb 04 2022
...Overview...
A weak shortwave moving through the southern Plains on Monday
should shear out pretty quickly as it moves out of the Plains
Tuesday-Wednesday due to a building ridge over the western
Atlantic. This shortwave should at least generate enhanced
rainfall along/north of the Gulf Coast on Monday. After this,
another shortwave is forecast to amplify out of the West, sending
an amplified and elongated trough into the central U.S. by
Thursday. By Friday, broad longwave troughing should cover much of
the CONUS as strong ridging builds over the East Pacific and
Western Atlantic. This evolution is expected to bring widespread
precipitation along a leading frontal boundary into the eastern
third of the country mid-late next week, with potential for wintry
weather on the backside of the system.
...Guidance Evaluation/Predictability Assessment...
For the most part, the guidance shows pretty good agreement on the
overall large scale pattern, but plenty of continued uncertainty
in the details. The 27/12z UKMET remained a notable outlier for
the initial shortwave through the Southern Plains/Gulf Coast on
Monday, but the 28/00z run trended a little slower and more in
line with the rest of the guidance. For the next system digging
into the Western/Central U.S. Tuesday-Thursday, the operational
models seem to be trending towards less separation of
northern/southern stream energy compared to previous runs, though
the UKMET again is problematic with maintaining more separation
between streams. For the first half of the period, WPC leaned
towards a non-UKMET deterministic model run consensus.
Larger differences across the board begin to arise during the
second half of the period. First concerning energy lifting towards
the Great Lakes/Northeast where the GFS is noticeably faster than
the ECMWF, which affects deepening low pressure into the Lower
Great Lakes/Northeast on Friday. Out West, uncertainties remain
with strength of upstream energy dropping into the mean trough on
Thursday. The past few runs of the ECMWF have been consistently
much weaker and faster with the energy as it rounds out the base
of the trough by Friday. The GFS had been consistently more
amplified/slower though the 27/18z run looked a lot like the
ECMWF, and the 00z run again a tad more amplified than the
previous run. The CMC is also stronger/slower. A look at
individual ensemble members and the means, suggest a more
amplified solution is possible (more so evident in the GEFS than
the ECENS members). Given the lingering uncertainties both with
the Northeast energy and the Western energy, the WPC forecast for
days 6 and 7 trended towards the means, but continued about 50
percent contribution from the latest available GFS/ECMWF for some
added definition to individual systems.
...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. Best potential at this time appears to be over
eastern Texas with lower confidence in details farther east. Some
aspects of this event may hinge on small-scale details not easily
resolved very far in advance. The northeastern Pacific upper
trough digging into the West Monday-Tuesday will spread moderate
amounts of rain and mountain snow from the Pacific Northwest
eastward and southeastward into much of the Rockies. Highest
totals are likely to be in the Pacific Northwest but should not be
too extreme. 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 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 the
central/south-central Plains northeastward through the Great
Lakes. 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.
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 normal are possible. Locally
higher values as much as 25 below normal are possible across the
far northern Plains. The below normal temps should 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.
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
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