Quick thoughts tonight as I'm eager to get some sleep for the typical early start tomorrow! Have finally been getting back into the gym lately, which is a very good thing, but I kicked my own butt today and can barely move the top half of my body, which also provides motivation to keep this brief and hit the hay.
Bottom line is that this week will be tumultuous and trying for meteorologists, but holds plenty of potential for winter lovers. By no means do I think the meteorological events of this week represent a culmination of winter - though a warming does appear in the cards heading into the start of February, plenty of cold air will rebuild in Alaska at that time, and there's good reason to believe it will dislodge by the middle to end of the month. In the meantime, this week delivers a very fast jet stream which brings, of course, volatility in the pattern and as with any fast flow, unpredictability in timing and therefore phasing...and therefore...intensity of prospective systems. From the simplest and very broad perspective, the longwave pattern features a northward weakening trend to the polar vortex, then a retrogression toward and eventually into Alaska. This eases the very fast and very confluent, flat flow over the Eastern United States, but with a series of northern and southern stream disturbances continuing, and the ability for some diffluence and some amplification, phasing becomes more likely as the week progresses. The first notable interaction is already on the map as of this Sunday night writing - a strong northern stream disturbance over the Northwest US from Montana to Washington, and intense upper level energy swinging from Northern CA to Northern NV. These two will interact in the coming 24-48 hours, then become absorbed in the fast and rather zonal flow. The merged version of these systems arrives to New England on Wednesday, with confluent flow shifting east to allow some diffluence and some amplification of the shortwave trough. With a tight baroclinic zone remaining - low level and mid level - this means healthy banded precipitation is likely in a relative quick-hitting but relatively intense event, aided by good dynamic forcing.
It appears right now as though that's only the warning shot, with the much more intense phasing in line for Friday. The longwave ridge cresting over Alaska at the same time the polar vortex shifts west toward that state provides a great scenario to break a chunk of substantial northern stream energy off of the polar vortex and shove it southeast in the jet stream flow, already dancing with "southern" stream energy (though it will be modified after its trip to Alaska) swinging over the ridge. Together, these two systems interact while dropping into the mean longwave trough position over the Midwest, and the party begins. With the upper low trying to close off as it moves over Southern New England, precipitation type may be an issue for Southern areas, but the farther north one is, the more I'd anticipate a snow event, with the North Country/Ski Country in line for a great dumping heading into the weekend as meridional flow taps the Gulf of Mexico, and the system itself originated with Pacific moisture and polar vortex energy. Doesn't that just SOUND intriguing? The actual result could be quite impressive, but if you live and die by the guidance, you'd make a case that it will be impressive for the fish, not for the rest of us. You'd have a good case with plenty of numerical guidance support this early in the game, but logic argues New England is in the line of fire - ask yourself this: when's the last time you can remember a mean longwave trough position over the Midwest, great phasing, multiple moisture sources, excellent energy feed AND substantially relaxed confluence (it's much less by then) and had the storm develop too far EAST of New England. It doesn't happen - either the longwave trough position is too far west, or the storm is developing too far east. And those of you who've read this discussion for a long time know my line of thinking in these circumstances: Trust the most wholesome calculations. Consider how the guidance works. Consider the calculations that are done (this is where the quasi-geostrophic vorticity equation can be put to use!). The upper level forecast is far more "untouched" or dare I say "virgin" than the surface parameters. For now, I say we watch week's end closely.
And with that, my arms collapse on the keyboard. Lower body tomorrow. And more on the weather. ;)
Matt
