Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
156 PM EST Wed Feb 09 2022
Valid 12Z Sat Feb 12 2022 - 12Z Wed Feb 16 2022
...Weather Pattern Overview...
Guidance continues to show a significant upper-level pattern
change over the course of the period. The West Coast
ridge/eastern trough configuration this weekend should transition
toward an amplified western trough and southwesterly mean flow
farther east, as a shortwave traversing the North Pacific
ultimately drops southeastward downstream from a building Pacific
ridge likely to reach near 140W longitude by the middle of next
week. Within the upper trough crossing the East, some details
seem to be more uncertain than 24 hours ago--affecting specifics
of low pressure expected to develop off the East Coast around
Sunday-Sunday night, along with the corresponding moisture shield.
There are also detail questions for the trough digging into the
West during the first half of next week, affecting specifics of
associated precipitation and the leading wavy cold front.
Precipitation should increase over the central U.S. around midweek
as low level flow from the Gulf begins to interact with this
front.
...Guidance Evaluation/Predictability Assessment...
Compared to earlier runs, some guidance has noticeably diverged
for the eastern U.S./western Atlantic evolution around
Sunday-Monday. There is still a relative majority that shows
offshore development in response to energy within the upper trough
remaining open. However the 00Z UKMET/12Z CMC have a closed upper
low crossing the Great Lakes region, drawing the surface low
closer to the East Coast and spreading much more precipitation
across the Northeast. Meanwhile some GFS runs have been sharp
enough with energy farther south to emphasize the central-southern
Appalachians into Mid-Atlantic for precipitation while keeping the
developing low far enough offshore just to brush southern/eastern
New England. Recent ECMWF runs have tended to be lighter/more
suppressed with its snow. The 00Z UKMET/12Z CMC scenario is a
relative minority among ensembles (but within the envelope) thus
requiring minimal weight for a single deterministic forecast, but
taken as a whole there is somewhat more of a signal for at least
some snow over parts of the Mid-Atlantic/Northeast as ensemble
means had been hinting.
Meanwhile most models and means have come into better than average
agreement for the upper trough digging into the West, relative to
typical 5-7 day forecasts. There is still some debate over
whether an embedded low may exist as it comes ashore (new 12Z
ECMWF adding to that cluster) and the 12Z UKMET is a little
southwest of models that show a low center at that time, but
ultimately by day 7 Wednesday the latest GFS/ECMWF/CMC runs all
show an upper low reaching the Southwest/Four Corners region while
the GEFS/ECens/CMCens means all imply such a low would exist at a
similar location.
Between these two features, in the Saturday-Monday time frame
models have been diverse and inconsistent with the details of a
weak clipper-type wave that may drop southeastward between the
Plains and west of the Appalachians before dissipating. These
issues correspond to varying depictions of shortwave energy
forecast to feed into the mean trough aloft crossing the East.
Guidance behavior up to this point as well as the small scale of
the feature yield low confidence in any particular solution.
The early-period operational model blend of 00Z/06Z guidance
placed the least weight on the UKMET given its lower-probability
solution over the East. Favorable guidance comparisons led to
transitioning the forecast blend toward the 06Z GFS/GEFS mean and
00Z ECMWF/ECMWF mean/CMC by days 6-7 Tuesday-Wednesday.
...Weather Highlights/Threats...
Brisk winds and colder air behind the system tracking just north
of Maine on Saturday should support an episode of light to
moderate lake effect snow across portions of Michigan and upstate
New York. Expect low pressure to form along the trailing front
near the East Coast by Sunday, but with lower than desired
confidence in the strength/track of the system and
coverage/intensity of associated precipitation. Recent trends are
at least signaling potential for some snow from the
central-southern Appalachians into the Mid-Atlantic and
southern/eastern New England with rain possible over parts of the
Southeast/Florida. However the current possibilities for the
Mid-Atlantic/Northeast still range between minimal and significant
snowfall. Continue to monitor forecasts of this system closely.
Expect the upper trough/wavy front moving into the West early next
week to bring an episode of rain and mountain snow, with highest
totals likely to extend from the Pacific Northwest into the
northern-central Rockies. Precipitation should increase in
coverage and intensity over the central/southern Plains and
vicinity by next Wednesday or so as the surface front interacts
with a strengthening low level flow of Gulf moisture. Some snow
may be possible from the central High Plains northeastward.
Many parts of the West will see well above normal temperatures
extend through the weekend with some areas seeing plus 10-20F
anomalies. Best potential for daily records will be over
California Saturday-Sunday. The upper trough approaching from the
Pacific will begin a cooling trend over the Pacific
Northwest/northern California by Monday while the Great Basin and
Southwest remain quite warm. Then expect moderately below normal
highs to spread across the West/Rockies by Tuesday-Wednesday.
Meanwhile the Plains will see a warming trend (up to plus 10-20F
or so anomalies) from the weekend into early next week before the
western front approaches. Areas near the East Coast will see a
warm day Saturday (plus 10F or greater anomalies) before passage
of a cold front, with trailing temperatures generally 10-20F below
normal progressing from the Mississippi Valley Saturday through
the East into early next week. The East will likely rebound to
near or above normal by next Wednesday.
Rausch
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