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I just realized that if this ULL had come down in winter with the same moisture levels, it would have resulted in a 10-12" snowstorm (assuming 10:1 ratios). The average high today is 77, compared to 50 in mid-January. And the precipitation all happened with temps below 55, so that would equate to temps below 28 in January.
Maybe even colder than that, because standard deviation is higher in January than May I would imagine.
I just realized that if this ULL had come down in winter with the same moisture levels, it would have resulted in a 10-12" snowstorm (assuming 10:1 ratios). The average high today is 77, compared to 50 in mid-January. And the precipitation all happened with temps below 55, so that would equate to temps below 28 in January.
Right on. Kinda hard to say exactly what it would result in. Depends how much cold air is with it even in winter but yeah, all this most likely would of been snow.. I can find a lot of past posts of ULLs but here's one Jan 31, 2015. I cant find one over the Mid Atlantic, need more time.
Quote:
Originally Posted by muslim12
What's you reasoning behind us seeing more of these ULL in the future.
One thinking is a Warmer Atlantic = more High Pressure around or ridging towards Greenland = More Blocking = More chances of a spinning storm at all levels including these ULLs = them diving south more because of the blocking.
They've always happened in the past, but I wonder if we saw more of them when the Atlantic was warmer vs cooler. Just a hunch. Another reason is a warmer Stratosphere which disrupts the Polar Vortex and or Polar Jet Stream south more provides these cold pockets of air which ball up and spin up. An Upper Low is basically a piece of the Polar Vortex which broke off.
Remember the rare Mexico Upper Low. Insane how far south that was breaking record cold and snow down there.
I can find a lot of past posts of ULLs but here's one Jan 31, 2015. I cant find one over the Mid Atlantic, need more time.
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Looked through my files....Found one. February 13, 2014. Dropped down to South Carolina. 400,000 were without power from snow and ice in southeast states. Can't find a temp map I think I was more focused on the snow and cold up here but did post a few stuff from down south and Mid Atlantic.
2. With the upper level low intensifying in the northern Pacific, a ridge becomes sustained over western North America. The ridge is a direct result of the trough in the northern Pacific. While air rises in association with a trough, air sinks under a strong ridge. The sinking air warms and with strong 500 MB heights (that’s how we measure upper level ridges) that sinking air gets very hot. Thus you end up with a dry, hot weather pattern over western Canada, the northern Rockies, and the Northern Plains in the United States.
3. Now, remember the SSTA in the Atlantic? Again, we are dealing with thermal dynamics. We have very warm water in the western Atlantic and very cold water in the northeastern Atlantic. This clash of air masses is leading to a trough over the northwestern Atlantic which acts like a block. Think of this block like a traffic jam. So, the result of this, combined with a ridge in the West is a sustained trough and/or upper level low over the Eastern United States. This is why the Philadelphia and New York City metropolitan areas have seen plenty of rainfall of late.
4. So, think back to your high school physics class and remember Conservation of Mass. You must have a thermal and mass balance in the atmosphere. This is why we have storms. The upper level lows in the Pacific and over the Eastern United States balance the ridge over western North America. The ridge intensifies and as a result, so two the two troughs/upper level lows, which leads to a feed back loop until the block is broken.
So you take this pattern with what was already a warm winter due to the combination of El Nino and the positive PDO, and you end up with a low level environment in Alberta, Canada that is supportive for forecast fires. I should note, that this very same pattern was shifted east last month and lead to some fire concerns in New Jersey a few weeks back.
This process is not unusual. In fact, there are several cases of these dangerous fires throughout western North America. If you want to research past fire events in Canada, go here.
Maybe even colder than that, because standard deviation is higher in January than May I would imagine.
ULL rarely get temps below 30 in winter. I definetely think if one of these ULL lows with this strength hit in winter we would have a good snowstorm, temps would probably be in the upper 20s at coldest. Most ULL that hit in the winter pissbthe the southern forumers at americanwx because temps are so marginal, normally sitting around 35, close to snow temps but not there yet. I imagine though one of this strength would have lead to at least patchy frost down in Miami. Similiar to 2010.
Nice explanation! Would be an epic winter pattern for us down south.
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