December 29, 2001
All is quiet and cold on the homefront, unless of course you reside in Buffalo, New York where they have unofficially received 84.5 inches of Lake Effect snow since Christmas Eve. Here are a few facts to consider: The snowiest month in Buffalo history with an unofficial total of 86". The old record of 68.4 inches had stood since December 1985. The 35.4 inches of snow that fell from 6 a.m. Thursday to 6 a.m. Friday ranks as the second-highest 24-hour total in Buffalo history. The record is 37.9 inches, Dec. 9-10, 1995. But not to fear fellow weather friends in the Northeast, our time for fun is fastly approaching.
Although parts of the Northeast have already seen their first measurable snows of the winter season (upstate and western NY, ME, VT, NH, Western Mass, for example), the major population centers along the East Coast have not. I have received a few concerns about why we have finally gotten the cold air to settle in, but why we aren't seeing much in the way of storminess at the moment. In a nutshell, the NAO has gone severely negative with ridging ocurring near Greenland. This in turn forces the Polar Vortex farther South. Orientation/alignment of the PV is what usually determines where our developing storm systems will go. Well, the PV delivered colder air to the nation East of the Rockies, but the negatively tilted alignment of the mean trough in correlation with the PV has been more WSW to ENE rather than the favorable SSW to NNE when vortices have rounded the base of the said trough. Another factor in the lack of storminess has been the almost complete disappearence of the SE ridge. With the lack of any blocking mechanism in the SE, as disturbances press South and East, they are more prone to head off the SE coast as opposed to being blocked and heading Northward. Remember though, you don't 'need' a ridge to be in place near the SE for a storm to head North or Notheast. Some of the bigger systems can actually pump up their own ridge downstream.
Things over the next 48 hours (at the very least) look relatively quiet in the Northeast, save for the favored snowbelts downwind of the Great Lakes. Believe it or not, more LES will clobber the Buffalo area over the next several days, so the possibility of >100" in one week is not out of the question for the area. For the Philadelphia area, the persistent West/Northwest flow will prevail
with partly cloudy skies the story over the weekend. Highs Saturday around 40. Highs on Sunday in the upper 30s. For both New Year's Eve and New Year's Day, expect partly sunny skies with highs around freezing to the mid 30s.
While many of us are celebrating the ringing in of the New Year, Mother Nature may be quietly (at least initially) setting the stage for what *could* be the first widespread wintry weather event of the season in parts of the East. Generally, I would save such discussion for the Six to Ten Day Trend, but at least in this case, the ingredients leading up to this potential event fall within the medium range.
Needless to say, to get a result of "D", variables A,B, and C need to come beforehand, so any speculation on storm track at this time would be absurd. Here's what guidance is generally portraying. During the day on Monday, a shortwave will be headed South near Montana. That piece of H5 energy looks the be the biggest piece of the puzzle for any forecast of a winter storm middle to end of the week. Meanwhile, later Monday and into Tuesday, a weak wave of low pressure will be emerging from the Gulf of Mexico on it's trek across Florida and finally out to sea. At this point, I see no reason to believe that this weak low pressure center will affect anyone in the Northeast. There is no mechanism to sharpen the trough. The jet max is already exiting the trough with very little energy on the back side to amplify the flow much more. Needless to say, this is NOT the potential that guidance hints at next week.
While this is happening at the surface, the shortwave in Montana is continuing to head South thanks in part to the thumblike ridge projection near the West Coast forcing it up and over. Meanwhile, another vortmax is diving Southeastward across California and into the desert Southwest on Tuesday. Later on Tuesday, it appears that the two pieces of energy will try to merge or undergo a partial phase near the Four Corners region. This is all taking place at the bottom of the very positively tilted trough which extends from Quebec (the PV) and into the Four Corners region. At the surface on Wednesday, an area of lower pressure is beginning to develop in the Gulf of Mexico. Looking at the surface alone on paper for mid week, it is the type of thing that causes a snowlover to lose sleep over the course of the next few guidance suites in anticipation of the Gulf low headed up the Eastern Seaboard. However, up in the atmosphere is a whole other story. Obviously, this far out into the future (6 days?), guidance it not known to be 100% correct on every aspect of the weather forecast. Suffice to say, there are several minor details (A,B, and C) that could send our 'potential' into another missed opportunity.
In general, guidance is fairly close tonight in regards to the setup of our potential storm later next week. The key differences are over the West at 500mbs (don't we say this every storm?) and the retrogression of the PV farther North. In my opinion, if we want snow here, a phase of the shortwaves over the Four Corners region is not very good. The solutions with the best scenarios keep the California vortex going into the desert Southwest and then across the deep South before finally phasing with the PV as it closes off farther south and east allowing for the trough to go to a negative tilt and sending the Gulf low up the coast. Anyway, for a discussion 6 days out, I've gotten into too much detail.
In short, there are three main shortwaves that we need to watch for the middle to latter part of next week. Vortmax #1: emerging near Montana on Monday. Vortmax #2: digging South across California on Monday and eventually into the desert Southwest. Vortmax #3: Piece of energy rounding the base of the mean PV trough around Wednesday. This vort could actually close off an H5 low somewhere in the midwest. The way I see it, if we can keep s/w's 1 and 2 separate, or just merge slightly, that will keep their trajectory farther South as they move into the East side of the mean PV trough elongated from Quebec into the Four Corners. This will allow for a better chance of phasing when s/w #3 closes off and dives into the Plains midweek. On the same note, if this happens too late or the flow is a bit too flat (ala AVN0Z), the system will be too far East. So, the potential is there, but I am NOT sold on a solution just yet. Another suite or two of guidance should give us a general idea as to where or 'if' the energy phases at all.
Lot's of fine tuning on the horizon and plenty of time to do it. Highs in the 30's each day (see above for more details). In short, quiet and cold through New Year's Day with the potential for snow in parts of the East mid to late week as a storm system develops in the Gulf of Mexico. THere is potential for a storm system to pull out of the Gulf of Mexico the second half of the week. Remember, this is 6 days away at least, and there is no 'clear cut' solution available at this time. If I were forced to hedge one way or another, I would headge on the side of a storm system developing and giving parts of the East snowfall later in the week. East doesn't necessarily mean "North"east though as we can't forget our Southern friends. I will not update again until later in the weekend. Take care!
S.B.
