Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
149 AM EST Mon Feb 21 2022
Valid 12Z Thu Feb 24 2022 - 12Z Mon Feb 28 2022
...Heavy to excessive rainfall threat from the Mid-South to the
Mid-Atlantic Thursday along with a significant heavy snow/ice
threat from the Mid-Mississippi Valley northeastward to the
Northeast Thursday-Friday...
...Guidance Evaluation/Predictability Assessment...
Models and ensembles offer a similar mid-larger scale flow
evolution in a pattern with above normal overall predictability.
An 18 UTC GFS and 12 UTC ECMWF/UKMET/Canadian composite along with
the 01 UTC National Blend of Models seems to provide a good
forecast basis days 3-5 (Thursday-Saturday). Blending of these
well clustered models tends to mitigate smaller scale system
variances consistent with predictability. Newer 00 UTC guidance is
consistent. The WPC product suite into days 6/7 was mainly derived
from the ECMWF ensemble mean that maintains a slightly more
amplified Southeast upper ridge that often lingers on the stronger
side of the full envelope of solutions in this type of pattern.
This plan maintains great WPC product continuity.
...Pattern Overview and Weather Highlights/Threats...
A cold pattern ensues this week as Canadian high pressure settles
across much of the lower 48. Upper level troughs will dig through
the West/Southwest, with ejecting energies and induced frontal
waves progressing downstream overtop a warming Southeast upper
ridge. A main upper trough will eject out through the
south-central Plains and Mid-South/OH Valley later this week as
amplified ridging builds from the east Pacific to the West Coast.
This will favor a heavy to excessive rainfall threat from the
Mid-South to the Mid-Atlantic Thursday, along with a significant
heavy snow/ice threat from the cooled Mid-Mississippi Valley
northeastward through Ohio Valley states to the Northeast Thursday
into Friday. Later, northeast Pacific upper trough energies and
precipitation will slowly work toward the Pacific Northwest days
6/7 (Sun/next Mon). This occurs as lead upper troughing ejects out
from the West/Southwest to across the southern U.S. tier to
modestly renew waves and precipitation, albeit with more uncertain
phasing with an amplifying/cold reinforcing northern stream upper
trough then set to dig into the east-central U.S..
The cold high pressure surge will spread much below temperatures
across much of the western and central U.S. by mid-late week to
include widespread record cold values, especially frigid from the
northern High Plains to the Northern/Central Plains where daytime
highs and overnight lows could be 30-40+ degrees below normal.
This very cold air will spread, but gradually modify later week
across the Midwest/East. Meanwhile, much above normal pre-frontal
temperatures are expected across the Southeast/East with some
record warmth likely, especially overnight mins with upper level
ridging and enhanced pre-frontal moisture into the region.
Schichtel
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