Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
207 PM EST Mon Jan 24 2022
Valid 12Z Thu Jan 27 2022 - 12Z Mon Jan 31 2022
...Winter Coastal Storm Threat from the Mid-Atlantic to especially
New England Friday/Weekend...
...Overview...
Guidance still shows a mean upper level pattern that features
troughing over the East, varying degrees of ridging over the West,
and a developing northeastern Pacific trough that may approach the
West Coast early next week. Within this agreeable regime there are
lingering uncertainties regarding specifics of an eastern U.S.
amplified trough that has become more likely support a significant
and rapidly deepening western Atlantic coastal storm Friday into
the weekend with effects from the Mid-Atlantic to New England in
particular, as well as for a lead Pacific shortwave approaching
the West Coast by Sat. There are also lingering differences with
details of a later period northeastern Pacific trough, affecting
how much moisture reaches the Northwest. However, these
differences are now less profound than earlier.
...Guidance Evaluation/Predictability Assessment...
Even though the large scale pattern evolution has been rather
consistent in recent guidance, embedded areas of uncertainty
involve aspects that are smaller in scale and have lead to lower
predictability. However, forecast spread has decreased with the
latest couple model and ensemble runs whose systems are now better
clustered, bolstering forecast confidence. The WPC medium range
product suite was mainly derived from a composite blend of the
GFS/ECMWF/Canadian Day 3-5 (Thu-Sat) along with supportive
ensembles and the National Blend of Models before transitioning to
just the GEFS/ECMWF ensemble means and NBM into Day 6/7 (Sun/Mon).
I did apply some manual adjustments to offset composite smoothing.
These were primarily to ensure sufficient coastal storm depth
consistent with overall support, trending deeper than WPC
continuity given improved forecast clustering, ensemble member
probabilities, and a deeper/closer track to the coast guidance
trends.
...Weather Highlights/Threats...
Key Messages for January 28-30 (Friday-Weekend) Winter Storm:
Confidence is increasing that a significant winter storm will
create considerable impacts Friday through the weekend from the
Mid-Atlantic through the Northeast. While uncertainty continues
with the track and intensity of this system, it is becoming more
likely that it will bring significant snow, sleet, and freezing
rain to the region, including the I-95 metropolitan areas.
Hazardous travel conditions are possible due to the combination of
snow, sleet, freezing rain, and wind. Close to the immediate
Atlantic coastline, strong winds combined with high astronomical
tides may lead to coastal flooding. Please continue to monitor for
future updates as this system develops.
Elsewhere, some locations near the West Coast may see an increase
in precipitation with an approaching shortwave/possible compact
upper low late week into the weekend. This energy should
eventually support some precipitation over the southern
Plains/western half of the Gulf Coast early next week. Flow ahead
of a northeastern Pacific upper trough should bring rain and
mountain snow into the Northwest into early next week. A wavy
frontal system should also bring mostly light snow to the Great
Lakes and Appalachians late this week. One or more trailing weak
waves may also produce scattered light snow over areas from the
extreme northern tier into the Great Lakes.
Mainly the East will experience periods with much below normal
temperatures (10-20F below normal). Much of the West should
continue to see moderately above normal temperatures (5-10F+
anomalies) while the northern and central Plains will likely see
multiple warm days with temperatures 10-20F above normal,
especially starting the weekend.
Rausch/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