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| Image courtesy Tropical Tidbits |
I am watching the potential for a winter storm between the 8th and 12th of February, with those dates very fluid and not nearly set in stone at this moment.
The above image shows Hour 312 of the 0z GFS model. We can see a modest storm system ejecting from the Rockies and producing wide precipitation shields across the Plains and down towards the Gulf Coast. Most notably is an area of heavy snow occurring in the Central Plains, where several inches of snow may be trying to accumulate. I cannot determine just how much, as the source of these graphics does not provide such a luxury. Nonetheless, accumulating snow would be falling in the Plains, with rain in the Southern Plains in a situation that may even produce some elevated convection.
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| Image courtesy Tropical Tidbits |
Fast-forwarding to Hour 336 (12 hours later), we find ourselves with even heavier snow now occurring in the Midwest and western Great Lakes, into the Ohio Valley and Mid-Atlantic. I could see a very good accumulating snow event come out of this (that is, if this forecast even reappears in the next week), but again, I am in no position to determine exact amounts. Making a quick glance over to the rainy side I see heavy rain now ongoing across the Gulf Coast and Southeast. While the low pressure system is further north and not right on the Gulf Coast, I could still see the chance for some elevated convection if the cold front brings up the rear of the precipitation with some solid cool air.
So, you're most likely wondering why I am spending my time typing this much about a storm way out in the long long range of the GFS.
The answer: Lezak's Recurring Cycle (LRC).
The LRC involves a cycling pattern that repeats, or 'cycles' every 40-60 days. Each cycle length is different each year, and the pattern is most prevalent from winter into spring. This year, the cycle length is roughly 53 days. If we were to go back 53 days from February 10th, we would find ourselves on the date of December 21st, 2012- supposedly the day of the apocalypse.
This was the atmospheric set-up on the 21st. We had a deep low pressure system in the Central Great Lakes and Ohio Valley. W also observed high pressure in the Canadian Maritimes into New England, as well as in the Plains and Rockies. Deep low pressure was observed off the coast of the Pacific Northwest.
Now that we've got a look at December 21st, let's go to the forecast day of February 10th and see if we can spot any similarities that may validate or void this potential winter storm.
A quick comparison between the two yields many similarities. Let's list them all- First, we see a deep low pressure system once again present in the Ohio Valley, which is the main potential for the storm. We see the high pressure systems in the Plains and Canadian Maritimes into the New England region. The big thing we're missing is the deep low pressure system offshore of the Pacific Northwest, but that will likely come back into the model's field of vision as the time draws closer. Also worth nothing is the forecasted high pressure centered in eastern Greenland, resulting in an east-based negative NAO. The east-based negative NAO is favorable for cold and snow to reach the Central US over the Northeast, increasing the validity of this forecast.
We have suddenly established these two dates as very similar. The atmospheric pattern over North America (while not 100% spot-on) is similar enough that my confidence in this particular forecast is increasing. Now, we will definitely see this forecasted storm come and go in future model runs, but seeing such a close match between this forecast and December 21st tells me we should be watching for this timeframe to verify.
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