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Wintry 1/20 - 1/23 Winter Storm

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Latest thoughts from WPC...


Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
210 AM EST Sun Jan 16 2022

Valid 12Z Wed Jan 19 2022 - 12Z Sun Jan 23 2022

...Pattern Overview...

...Of the main shortwaves, the first should slide over the Great Lakes into the Northeast Wednesday and Thursday, with the next tending to dig more sharply into the South Friday and up off the Mid-Atlantic/Southeast coast Saturday. There is significant forecast spread and run to run uncertainty with this latter feature and associated mid-winter weather focus with frontal wave/coastal low genesis.

...The wavy trailing cold front on the leading edge of this Arctic blast will gain some Gulf moisture to fuel an emerging area of precipitation up from the South/Southeast. Guidance varies however with potential focus due to ample run to run trough track/separation uncertainty aloft later week into the weekend. The pattern offers potential into later week for an enhanced swath of overrunning snow/ice on the northern periphery of activity. A cluster of multi-model ensemble members along with in particular the 18 UTC GFS and now the latest 00UTC ECMWF/Canadian models, are much more robust with frontal wave to coastal low/storm genesis and mid-winter precipitation extent across the region and up the East Coast at these longer time periods. However, the 00 UTC GFS has backed off. The preferred model and composite trends WPC product continuity toward more organized and closer to the coast genesis and track, but not at this point as strong as some of the models.

Schichtel
 
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This looks ”better” than our current storm, as in I don’t think the current storm looked this good 6-7 days prior, at least for the I20 corridor. I’m pretty convinced ATL benefits most from overrunning setups just like this, with 12/7/17 & 1/28/14 on my mind (anyone have any other good ex?)
 
From RAH:

Uncertainty continues to remain for the Fri-Sat timeframe. The
GFS/Canadian/ECMWF all show a deeper mid-level trough digging from
the Great Plains and Midwest region into the southeast US late Fri
night. However, the models differ on the overall position, track,
and intensity of the shortwave, as well as in regards to the track
and development of a potential Miller Type A surface low tracking
along the western Atlantic along the arctic frontal boundary. The
GFS is faster and more offshore by Sat, while the ECMWF/Canadian are
closer to the coast. The cold air in place would largely favor snow,
but if the low moves further inland, it could result in a mix of
rain or snow. Many of the GEFS/NAEFS and ECMWF ensemble members show
precipitation in this timeframe, which would favor a solution closer
to the ECMWF/Canadian, so have kept chances for snow toward the end
of the period.
&&
 
Euro still with the perfect track and more amped. Would be almost blizzard like.


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GSP Discussion...

Otherwise, addressing the next elephant in the room... the latest global models (sans the GFS) are interesting to say the least in depicting yet another winter storm for the Fri/Sat time frame, and in fact the 00Z ECMWF has eliminated the substantive timing differences that did exist between its 12Z run and the 12Z Canadian model. As we always like to say when the global models advertise such shenanigans beyond Day 5 "expectations should be managed," and there is still plenty of time for run-to-run flipping and flopping, as is common with Southeast coastal storms beyond the short term. As such, our forecast PoPs in the Fri/Fri night time frame are limited to low chance for the time being. Other than a sliver of rain/snow across the upper Savannah River Valley, precip type is currently advertised as snow...and only snow...during that time frame.
 
Area Forecast Discussion
National Weather Service Birmingham AL
352 AM CST Sun Jan 16 2022
.LONG TERM...

An Arctic air mass looks to invade much of the eastern CONUS late
in the week. Another shortwave rounds the base of the trough, with a
lot of spread in ensemble members as to whether there is a quicker
unphased solution or a slower more phased solution. The slower
solution would result in an area of low pressure forming in the
northeastern Gulf, while the quicker solution would not develop a
surface low until the Atlantic. The slower solution would result in
moisture returning to the area Thursday night/Friday while the
moisture would be much more limited with a quicker solution. Unlike
previous systems there is plenty of cold air present, but moisture
and forcing are uncertain. This results in a range of outcomes from
dry conditions to a winter storm. This is several days out and
certainly could change, but there is enough of a signal in ensemble
probabilistic guidance to at least mention a chance of a rain/snow
mix Friday with a low confidence mention of accumulations in the
HWO.
 
Morning FFC Discussion

.LONG TERM /Monday Night through Saturday/...

A dry ridge dominated Tuesday offers only a brief reprieve in the
active pattern as the next upper wave and translated sfc cold
front pushes into the area for Wednesday afternoon into Thursday
looking to initially generate mainly rain showers. Where it gets
interesting is how the models evolve with a secondary piece of
upper wave energy and potential coastal cyclogenesis along a
lingering enhanced moisture axis near the possibly more stalled
front for late Thursday and Friday. Both the GFS and Euro indicate
potential for this as the next round of wintry precip, though
there is lack of consensus and run-to-run consistency. The latest
GFS indicates more of a clipper type system and progged thermal
profile suggest primarily all snow p-type, while the Euro has more
of the coastal low influence and more lingering moisture with the
upper trough amplification digging farther south supporting
various p-types and what could be snow in parts of the north and
west and freezing rain in the south and east. Given the
uncertainty with this far out and lack of agreement, have not
included freezing rain in the grids but have advertised some snow
potential.
 
griteater said:
GSP Discussion...

Otherwise, addressing the next elephant in the room... the latest global models (sans the GFS) are interesting to say the least in depicting yet another winter storm for the Fri/Sat time frame, and in fact the 00Z ECMWF has eliminated the substantive timing differences that did exist between its 12Z run and the 12Z Canadian model. As we always like to say when the global models advertise such shenanigans beyond Day 5 "expectations should be managed," and there is still plenty of time for run-to-run flipping and flopping, as is common with Southeast coastal storms beyond the short term. As such, our forecast PoPs in the Fri/Fri night time frame are limited to low chance for the time being. Other than a sliver of rain/snow across the upper Savannah River Valley, precip type is currently advertised as snow...and only snow...during that time frame.
Click to expand...
GSP seems a little bullish for them considering this is still a few days out. Perhaps it’s because there appears to a stronger cold push than our current, but GSP already has heavy snow in my point forecast for Friday night. Also TWC has highs on Friday for the entire CLT metro area in the 20s with snow. Also GSP has my low on Friday night of 19 with that heavy snow.
 
Chazwin said:
GSP seems a little bullish for them considering this is still a few days out. Perhaps it’s because there appears to a stronger cold push than our current, but GSP already has heavy snow in my point forecast for Friday night. Also TWC has highs on Friday for the entire CLT metro area in the 20s with snow. Also GSP has my low on Friday night of 19 with that heavy snow.
Click to expand...

That's crazy for that far out.


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Do these new models have any snow going over ATL area or is it gonna be below this time?
 
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