Winter Weather Comin' Back into Town

A more wintry weather pattern is set to unfold as we head into next weekend. Late afternoon guidance suggesting a cold front teaming up with a Nor'Easter pushing through Thursday into Friday with some general snow and deeper cold air to follow. Higher potential for localized lake snows to develop next weekend. This colder flow may stick around for some time to follow. ..great news for snow lovers and skiers alike. Still have to keep in mind latest ENSO discussion from the Climate Prediction Center keeps La Nina alive through the remainder of the winter season. This hints at more of a roller-coaster winter season overall, including arctic shots and warmer than average periods as we've seen thus far.

Just Some Nice Photos

I know that most of these photos are not from this time of year, but I thought they were nice anyways. I just happen to be looking through some old photos that viewers had submitted in the past and these three jumped out at me. I hope you enjoy them.

Snow Chances

The current projected path for a nor'easter on Sun-Mon takes the main energy too far to the east for us to receive heavy amounts. However, as noted on the previous thread, the GFS model has had a tendency to initially move storms further east, and then nudge them back to the N & W in successive runs--so we will have to keep an eye on this system. It's currently most likely to give NYC and Boston a run for their money, with snow & strong winds.

We had our December storm (a month ago on a Sunday, approximately) which delivered a foot+ to the airport and points north, and that system kept getting nudged further N & W as its approach grew closer (which led to rain & mixed precip in much of the srn tier). One big difference this time is that only a weak low will be inland, closer to us. In December's storm, the original interior low was quite well developed, and was slower to transfer its energy to the coastal low. This time around, the coastal low will be the primary low from nearly the outset. As of this writing, we're likely to see some light, wet snow arrive later Sunday, and may see a couple of inches of accumulating, water-laden snow Sunday night into Monday morning. The Navy NOGAPS model takes this system even further out to sea, the UKMET only goes out 72 hours, and the ECWMF (European) model is not terribly dissimilar to the GFS solution.

I'll have more info on this Friday, of course. A somewhat more wintry pattern appears likely later next week as far as temps go, but precipitation is much less certain.

So, What Happened This Morning?

Let me preface this technical explanation with this: if there are any mets or physicists checking this out, I am taking certain liberties and shortcuts in this discussion. That out of the way, here goes:

Often, when there is a strong cold front with high speed low level jetstream winds not far from the surface, a very strong barometric pressure gradient occurs with the passage of the front. Most of the bloggers here have heard of ISOBARS--lines of equal barometric pressure taken at surface observation points. In this type of pattern experienced early this morning, we looked at another parameter: ISALLOBARS--lines of an equal rate of barometric pressure changes (up or down a certain number of millibars). Meteorologists look for ISALLOBARIC COUPLETS with the passage of fronts to see if there is a very tight gradient of pressure falls and rises just ahead of and just behind the front. ISALLOBARIC COUPLETS, when tight and strong enough, enable strong winds aloft to mix down to the surface more readily. Late last night, an ISALLOBARIC COUPLET of a 5mb change in 3 hours was considered impressive enough to forecast strong winds with gusts of up to 50 mph possible. 5mb in 3 hours is quite a significant couplet. But, instead, a shocking 14mb/3 hour change occurred. Sharp falls ahead of the front and steep rises immediately behind the front create a "wind tunnel" toward the east into the weak pressure from the sharp jump (here's the shorthand: "nature abhors a vacuum"). The strength of this ISALLOBARIC COUPLET was simply not evident in last evening's soundings or model runs. A fairly strong couplet was evident, but not a powerful 14mb/5hr couplet--which is relatively rare.

As to why the couplet strengthened so much, I still don't have all the answers. A similar but worse case occurred 2 nights ago over Wisconsin, when tornadoes and damaging straightline winds developed unexpectedly. But by last evening, there was scant evidence of such strengthening at our latitude. The Storm Prediction Center didn't have us at risk for severe weather, either. The risk was believed to be further to the SW (where conditions were far more unstable, and there was more spin potential in the lower atmosphere).

One element we did call correctly was on the timing. Although the Wind Advisory was not to go into effect until 7am, we did say at 11 that some folks would receive an early wakeup call from the strong winds around 4:30 to 5am. Not good enough, but at least it's something....

Strong--not High--Winds on the Way

Winds will strengthen overnight, after another incredibly warm day. Some gusts will exceed 40 mph later this evening, particularly along the L Erie shore and on s tier ridges, where the downslope winds tend to be strongest. Shwrs will gradually increase this evening, and become numerous and somewhat heavier after midnight, with a few tshwrs thrown in. As we've discussed, the airmass behind the predawn cold front is Pacific in origin, so cooling is not going to be impressive for this time of the year. Strong winds continue Wednesday, diminishing late, with an NWS Wind Advisory in effect at 7am. Gusts may reach 50 mph, especially downwind of Lk Erie.

The next storm system will move toward us with no supply of Arctic air to tap until it's passed, so some rain will move in Thursday evening. The rain may mix with or turn to a bit of snow on Friday. Weekend temperatures will be seasonably chilly. The turn to a more wintry pattern is still on tap for next week, with uncertain snow potential--nothing big showing up just yet which would have any reliability. The Operational GFS--the one you see on the internet--does show an impressive pattern shift to wintry (not extreme) conditions, but the Ensemble of other parallel GFS runs you don't see have a more moderate solution.

No doubt the ski resorts have taken a huge hit since Sunday. Looks like snow-making conditions will improve during the weekend and into early next week. It remains to be seen how much nature will help out after that time period.