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The Single Chair Weather Blog

Here is the 12z ECMWF 500mb vorticity forecast for January 4th, where we see two pieces of energy impacting different portions of the nation. A potentially life-threatening tornado episode is likely today across portions of Oklahoma, Kansas and Missouri. RADAR INDICATED A STORM CAPABLE OF PRODUCING A TORNADO. Now, the tornado threat will depend on how strong a system is and the proximity to the jet stream that will be displaced north. As long as this vortex of low pressure is in the GOA, there will be a somewhat continuous threat of precipitation- from snow to severe weather. By later Wednesday that wind direction is expected to turn and become more northwesterly allowing some of those snow showers to impact areas further south. It won’t be especially arctic with temperatures not too far from seasonable levels but remaining mostly sub-freezing on the mountains while creeping above freezing in the valley areas on Tuesday, Wednesday and Thursday.

The wind direction later Tuesday, Tuesday night and Wednesday appears light but blowing from the west, southwest which is likely to focus much of the convective snow activity on the far northern mountains of Vermont. We do have a weaker weather system that has consolidated a small amount of moisture but has done mostly south of Vermont on Christmas Eve. The catalyst for such discussion is something called “Sudden Stratospheric Warming” or “SSW”, a phenomenon which sometimes foreshadows extended periods of high latitude blocking in the jet stream and cold weather in lower North America. This positive NAO will keep the overall weather pattern quite progressive, meaning the probability of stagnating high and/or low pressure systems is lowered. The GFS Ensemble set shows the NAO descending from its moderate positive state to a more neutral position by the time January 2nd rolls around. The Sunday weather system has a follow-up act Monday/Tuesday that has looked more and more promising. Bleached areas of the affected colonies had died by September 2003, with areas that were essentially covered by more than 80% living coral decreasing to less than 10% visible living coral cover.

September 1922 – At Chalon-sur-Saone, little toads fell for 2 days. Expense: Cat vaccinations, spaying/neutering and flea and tick control are all a little cheaper than for dogs. Forecasts for the North Atlantic Oscillation (NAO) are also a bit messy, most likely due to the impending weather pattern shift. NAO that will arise as a result. The deep low in the Gulf of Alaska (GOA) will persistently spit out low pressure disturbances that will hit the US and come onshore to produce precipitation. The vortex in the GOA makes for a cause-effect relationship that produces a ridge of high pressure in much of the east half of the US. Also, there is a large ridge in the North US and a low pressure system in the south central US. I am cautiously optimistic with this forecast, as I think the teleconnections fit in nicely here, but models are notorious for shifting south in this time period, only to shift back north later on. The first will be the shifting of that deep trough along the west coast of Canada south into California, and then moving north and east into Montana, as this GFS Ensemble forecast shows on the morning of this coming Sunday.

That ridge then pushes the jet stream north, possibly as far north as the Canada/US border. I worry that the warm Gulf air moved both by the strong ridge will quickly interact with any low pressure system that may be present along the area delineated for a low pressure in the area. Now, looking at the individual 12z GFS Ensembles, it looks like a good portion of the East US may be under the gun at some point in the next few weeks. Certainly one of the snowiest I can remember in a while but no good thing lasts forever. We’ve had it very good the last two thirds of November. The last several days have seen a rather volatile pattern positioned over the Arctic and similar upper latitudes. The winter of 1958-1959 saw strong ridging/high pressure positioned over the north-central and northwest Pacific regions, with some stormier weather observed near the Gulf of Alaska.