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By now, you may have heard a major snowstorm or historic blizzard is in the forecast for the Ohio valley early next week. You will likely hear a lot of talk about this over Thanksgiving turkey and leftovers. Before you panic, read this.

Some would say I shouldn’t even mention this storm this early. I disagree and here is why.

1) This storm is likely to form and is likely to have high impacts somewhere.

2) A lot of people will be traveling and snow plow operators may be more occupied with the holiday weekend rather than preparing for snow.

3) It is useful to have advance knowledge as long as you keep the limitations of technology in perspective.

4) It is impossible to make a high likelihood forecast this far out and anyone who says otherwise is either lying or uninformed.

Computer models are showing a deepening storm system developing late this weekend and moving up the spine of the Appalachians. The best average of all these models as of this writing is roughly along the center line and arrow in the map above.

However, there is a larger cone of possible tracks and computer models currently disagree by thousands of miles, with ultimate tracks along the lines of the wider circled area.

For the Ohio valley to get a major snowstorm, the ultimate track would basically need to be right up that center line. The very worst case model at this time says that track could give Cincinnati a couple feet of snow. That will not happen.

Here are some keys to remember about some of the extreme snowfall amounts being seen on a few deterministic/ensemble members:

1) These static ratio amounts do not account for the very warm ground temperatures (remember Sunday`s temperatures are forecast to be  in the 50s).

2) These models do not take into account the degree of compaction that would occur with a long duration wet snow event that is leading to some of the very high totals

3) Boundary layer temperatures will remain 30-35 during any snow that falls which means slower accumulation rates and more compaction, especially during daylight hours.

4) This storm has no bitter arctic air in place or available to tap – unlike a very
similar setup 70 years ago when the Snow Bowl storm produced in
excess of 12-15″ in the Ohio valley. That storm had surface temperatures in the
single digits and teens.

5) Also pointing against the extreme solutions is a very narrow dendritic  growth zone – less than 100mb on forecast soundings. So we will need to watch computer model ensembles closely in the next couple of days to see if a trend emerges on a number of fronts.

This is definitely a forecast to stay tuned to through the holiday weekend. Those who will be traveling early next week or who plow snow need to know that a high impact snow storm is one possibility, of many.

At this time, Thanksgiving Day, characterizing this storm as a major blizzard is like characterizing a sports team as a world championship winner before the first game of the season is played. Yes, this storm has the players to compete, if there are no injuries and everything falls into place, but there are a lot of games to play between now and the end of the season (remember how the Reds had the players to compete this past season? How did that turn out?).

In the meantime, have a happy and blessed Thanksgiving.

Hazardous Weather Outlook
National Weather Service Wilmington OH
500 AM EST Thu Nov 26 2020

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Wayne-Fayette IN-Union IN-Franklin IN-Ripley-Dearborn-Ohio-
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Pendleton-Bracken-Robertson-Mason-Lewis-Hardin-Mercer-Auglaize-Darke-
Shelby-Logan-Union OH-Delaware-Miami-Champaign-Clark-Madison-
Franklin OH-Licking-Preble-Montgomery-Greene-Fayette OH-Pickaway-
Fairfield-Butler-Warren-Clinton-Ross-Hocking-Hamilton-Clermont-Brown-
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500 AM EST Thu Nov 26 2020

This Hazardous Weather Outlook is for East Central Indiana,
Southeast Indiana, Northeast Kentucky, Northern Kentucky, Central
Ohio, South Central Ohio, Southwest Ohio and West Central Ohio.

.DAY ONE…Today and tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN…Friday through Wednesday.

Rain will change to snow Monday into Tuesday across the area, with
gusty winds also possible. Accumulating snow is possible, but
confidence remains low on amounts and changeover timing in any
particular area.

It is worth noting that a significant shift in the weather pattern will be occurring as we head into the new week. We look safe for the holiday weekend but it looks like real winter may be arriving next week, coincident with the start of meteorological winter. Here is what the National Weather Service forecast discussion has to say about it:

We continue to monitor the forecast upper level pattern and the
subsequent surface pattern as we head into the second half of the
weekend into early next week. Northern stream energy with colder air
is still forecast to dig southeast into the Great Lakes. Meanwhile,
southern stream energy is also forecast to eject northeast from the
southern Plains into the Ohio Valley. How these two systems
interact/phase will be the key to potential impacts, particularly
the threat for snow and wind. As has been stated, there is still a
lot of time between now and Sunday/Monday for the models to come
into better agreement on storm system evolution. The signal is there
for a deepening surface low to affect the Ohio Valley and the
central Appalachians. This scenario would bring rain to the region
at first followed by a change over to snow as colder air is drawn
into the deepening system. This event could bring the first
accumulating snow of the season to our region and as such will have
to fine tune the forecast as we get closer. So, the forecast calls
for rain moving into the region late Sunday into Sunday night
followed by rain changing over to snow Monday into Monday night. The
system may occlude over the Great Lakes and spin in place for
awhile, thus keeping the threat for at least scattered snow showers
Tuesday into Tuesday night. These may end up lingering into the
middle of next week if the mid level flow becomes “blocky.” Highs in
the 50s on Sunday will tumble into highs in the 30s by early next
week. Lows will eventually cool down into the 20s.

Don’t believe early forecasts of a huge snowstorm. The weather blog wannabes are liable to have a field day with this. Just know that this is a possibility and plan accordingly. If you plow snow, it’s time to get your equipment ready if you haven’t yet. You may need it next week.

A lot can change in the next few days so stay tuned.