As we’re staring down the barrel of another very cold to occasionally Bitter cold week, it’s almost tempting for a meteorologist to cherry pick for favorable trends in the extended range. It does get tiring giving one wintry forecast after another, but I’m not going to succumb to that temptation.
Fact is, as cold as this week will be, there will be a little improvement in temperatures in the mean for next week. The 500 mb flow flattens somewhat for a few days, allowing more Pacific air to mix in with the Arctic air. That doesn’t equate to mild, but it does equate to more bearable. As I posted on the previous thread, a rapid thaw after this week would again spell probable trouble in the way of increased risk of new ice jams forming. A gradual thaw, of course, reduces that threat (not that we’re looking at anything yet you’d call a thaw). There also were signs over this past weekend that the PNA ridge was going to be building and the Great Lakes trough would be moving toward reamplification around March 9-10. As of today, that western ridge looks a bit less permanent and a little more progressive, and the eastern trough looks a bit shallower. If these ensemble mean solutions worked out, we’d be tolerably cool rather than truly cold–after this week. The operational ECMWF today wants to paint some synoptic snow into our region Sunday night-Monday night from a storm going by to our SE, while the GFS keeps that storm farther away.
This week’s snow will be sporadic and spotty, but no major storm is foreseen during the week.
Back to that extended range…there are still no signs of a fundamental pattern shift to western trough/eastern ridge with any staying power. The PNA ensemble and GFS outlook still point to a positive PNA further out in time, near the end of the extended range.
The big picture…a coming warmup…seems simple enough. There will be one. But the details are fuzzy and getting fuzzier. After a mostly uneventful February weekend, the 2nd half of which will be colder, a storm system will be approaching our region by late Monday or Monday night. The deterministic GFS is much faster than ECMWF or the Canadian with this low. The ECMWF on Friday actually slowed the low down further than its already slower solution, not bringing its snow in until after dark Monday. There still is enough warm advection so that some sleet might mix in and hold down accumulations, while the Canadian and GFS keep us with all snow. The ECMWF is slow enough so that snow or a mixture turning back to snow would still be around for the Tuesday AM commute.
After that system is by us, Pacific air will dominate for some days to come. Some additional moderation will occur on Wednesday into Thursday. However, this (Friday) evening’s models and ensembles are not quite so warm as previous runs, even in the warmest model for this time frame, the GFS. With that in mind, I’m having to shave a few degrees off the Wed and Thursday highs, though temps will still be above average. If it had been just one model and/or ensemble which took the edge off the peak warming, I would have left the numbers unchanged. But because both the ECMWF and the GFS do so, and the Canadian ensemble mean does so, I’m changing the numbers a little. The low 50s I’d put out for Thursday earlier today are now back to the mid 40s. Of course, all this could change in additional runs. But the overall trend is to make the warmup more irregular, with another Pacific cold front taking us back down a few degrees on Friday. The GFS deterministic model seems set on bringing a wet plains low up into the western Grt Lks on Saturday, while the ECMWF is less organized with this low. In any case, periods of rain with this warmup will add to the risk of ice jam and poor drainage flooding by late next week. The less reliable GFS deterministic run shows a sharp arctic front crossing our region next Sunday, bringing us quickly back into a significantly colder pattern. The ECMWF is a little slower with that cold progression.
While a colder pattern is assured for the following week, it remains unclear how much colder. The Canadian and GFS ensemble mean take us back to significantly colder than average, with a well defined western ridge/eastern trough. The ECMWF had been moving in that direction all along, but just to throw in an additional note of disarray, it flattens that ridge on the last day of the run in the ensemble. This could just be a signal of a strong Pacific short wave showing up. It’s impossible to know if that’s a trend, or a one day special. The other 2 ensemble means are now in good agreement on the western ridge through at least March 1st.
In looking at this harsh winter thus far, as of this posting we are now the 9th snowiest winter in Buffalo record keeping history through February 5th, with records going back to 1871. The Buffalo airport observatory snow total is now approaching what would be considered normal for the entire cold weather season, with plenty more wintry weather to come.
However, the overall upper air pattern will begin to “relax” later next week, allowing more Pacific air to mix in with the cold air masses from the arctic. There will be more ups and downs. In the mean, our temperatures will still be running below average, but not so FAR below average. There should also be a smattering of days in which the temps go above average…days like that have been hard to come by, as if you didn’t know. This same pattern favors above average precipitation, but the details of individual waves/storm systems in the flow cannot be seen beyond about 7 days out. In the next week coming, current indications point to some low impact light snow moving in later Saturday night into a portion of Sunday. There may be another brush with snow by Wednesday afternoon. Most models favor any stronger systems passing well to the south and east of our region, having little impact here during the next week. Of course, we’ll be keeping an eye on those systems for their tracks and intensities at 4Warn Weather.
After this last bout of brutally cold temperatures begins to fade by Thursday the 30th (it should be noted the Thursday moderation will be accompanied by gusty winds, however), we will be heading into what I call the “Tolerable Weeks.” By comparison, of course, to where we’ve been. The full latitude long wave ridge in the west will deamplify, with assaults by one short wave after another. The flattening of that ridge will allow more Pacific air to mix in with our modified arctic air, and the cross polar flow we’ve endured will shift well away from us. The polar vortex will also shift further east and northeast, aiming any such flow far to the north of our latitude.
In the place of our long wave trough will be a much broader, lower amplitude trough. The axis of this trough will shift to the west central U.S. for nearly a week, and then shift back toward the Great Lakes as we move through the 2nd week of February. That will probably mean colder temperatures, but nothing extreme is in sight during that period. When this trough axis is further west, it will favor more short waves moving up from the SW and probably increasing our overall precipitation. How much of that turns out to be synoptic snow cannot be seen at the time of this posting. And, as per usual, embedded short waves with their ups and downs cannot be seen much beyond day 7 either. But this may not be a dull period–just a more tolerable one. There are no signs in the 16 day period of a reamplification of that western ridge anywhere near N America or even the eastern Pacific. That may change in the 2nd half of February, of course.
The overall pattern of an exceptionally strong western ridge/eastern trough will be with us right through the end of the month. Within this unusually anomalous pattern will come a train of such frequent Canadian short waves (which have their origins far to the west & northwest of Canada) that the timing of thermal ebbs and flows will be quite difficult until we get closer to each event. As expected, there is disagreement between the deterministic/operational models in timing & amplitude of each wave. As of this midday Monday posting, there is decent agreement on the Thursday system we wrote about last week, and a more vigorous system passing to our north on Saturday-Sunday. Both the GFS and ECMWF show strong winds with the latter system, both in advance out of the SW and in its wake. These winds will assure some more blowing snow and miserable wind chill, even as temperatures may briefly moderate on Saturday ahead of the next polar front. Even with lighter winds much of the time during the work week, Wind Chill may occasionally reach Advisory criteria, albeit marginally, due to the Bitter Cold temperatures.
In the longer term, nothing has changed since last week. The PNA will relax around Feb 1, and moderation will develop with more Pacific influence. Heights in the ensemble means don’t suggest a warm pattern by any means…just warmER than the bitter cold pattern we’ll be enduring. As that western ridge flattens, the episodes of cross polar flow will cease, at least for awhile. What can’t possibly be seen in this time range is what ups and downs will develop in early February due to embedded short waves.
In the meantime, one of the greatest fears among operational mets, especially those of us in the public eye, is of a snowstorm hitting the NYC area for the Super Bowl. There is no way to even guess at that today, of course. But if it happened, it will be a case of the silly and worthless Farmers Almanac making a wild a__ guess and getting lucky (who among us has never done that?), thus insuring a victory for scientific illiteracy. Oh, the agony!
After the Blizzard of 2014, most of us feel we deserve a break. And we will get one, though not without complications. The thaw begins in earnest on Friday, but the further warming and the moderate rain developing during Saturday will heighten the danger of ice jam and poor drainage flooding in parts of WNY. It’s possible as much as 1″ of rain will fall, with temps well into the 40s. Ice jams are already believed to be in place on at least 3 Buffalo area creeks, and possibly the Cattaraugus Creek as well. Following this thaw, we’ll be returning to Seasonably Cold temperatures on Wednesday.
There has been much talk of more “Cross Polar” flow redeveloping later in the month. However, in latest ensemble and model runs, there are no signs of the kind of cross polar flow we’ve been having over an extended period. In the mean, our temperatures will run Below Average much of the time after next Tuesday and especially after the 19th or 20th. We’re not looking, though, at the sorts of extreme anomalies just gone through. In addition, the lone index which looks favorable for a western ridge, the PNA, is not matched (today) by a favorable AO or NAO. The mean flow does, on the other hand, somewhat favor above average precipitation. That+seasonably cold weather MAY = above average synoptic snowfall.
This is my late Saturday afternoon post on my Facebook Pages: It may be tempting to think on a relatively milder day like this that the forecast I’ve/We’ve been giving you concerning early next week may be hype. It’s not. Conditions will still be on the mild side Sunday, so that’s the day to get things which must be done outdoors done. Rain showers will precede this powerful cold front by early Sunday evening, after a day of above average temps. In the wake of this front by the predawn hours of Monday, temps will drop suddenly and the lingering rain will turn to a quick burst of snow, with a flash freeze on road surfaces. For the AM commute Monday, roads will be slippery (but with no heavy accumulation), and strong winds will develop, with gusts of 45 mph likely…possibly 50. Lk Effect Snow will slowly develop by midday and intensify during the afternoon, possibly beginning near the metro area. Heaviest amounts will occur in Ski Country over the course of 2 days, but the metro area will not be unscathed, with some oscillation to the band–which will extend well inland. Within the band, blinding whiteouts will develop due to the strong winds which will persist at least thru Tuesday. IMPORTANT: Wind Chill temperatures will reach depths we haven’t experienced in some years running from the -20s to -30 by Monday night through Tuesday. Wind Chill of this magnitude is Dangerous, and frostbite can occur in mere minutes. Stay in touch with Meteorologists Mike Cejka tonight and tom’w night, and Bryan Shaw on Sunday Wakeup. If you must drive through this coming lake effect snow, make sure you have your fuel topped off, an emergency kit in your car (blanket, energy bars, water, etc) and your cell phone. This will be a Severe Winter Weather Event, far outweighing the bitter cold we just went through.
After the rain, the power outages from the ice storm, and the still-in-progress Tonawanda Creek flooding (at the time of this posting), the return to wintry weather will prove to be relatively benign…at least at the outset. Some limited lake snow will develop toward Tuesday morning and into Tuesday across Chautauqua County and western Cattaraugus County, with moderate to marginally heavy amounts on some hills. Thanks to a synoptic trough, snow showers will flare up over much of WNY on Tuesday, giving many parts of WNY a shot at a White Christmas, albeit a thin coating.
What is the bigger story is the return of our oft-discussed “indices” to having a role in our longer term pattern. That’s opposed to the cold weather which has resulted from a ridge over the north Pacific and an eastern trough which encouraged a polar flow from NW Canada (not Siberia). For the first time this cold weather season, the PNA will be slightly positive/cold phrase, the NAO will trend to slightly negative/cold phase, and the AO looks to trend sharply negative, as it had been earlier in the autumn. The 500mb ensemble means in the ECMWF, GFS, and Canadian GEM all support a ridge closer to the US west coast and an eastern trough–with no signs of a return to any lasting period of mild weather. We’ve already had those symptoms, but our indices were out of phase–which is quite unusual. There will be some quick ups, but undoubtedly the downs will outweigh and outnumber the ups over the next couple of weeks, minimally.
Lake Erie has bounced back to 36. That won’t last long. There are no signs of any major synoptic snowstorm in the next 6-7 days, but ski resorts will be able to make new snow and get some occasional help from nature.
Even as I type this post on Monday, lingering though weakening lake effect snow continues well south, and a little well north of the metro area. After this dissipates, the weak clipper we talked about last week will still bring us a minor snowfall later Monday night into Tuesday AM which will prove barely noticeable in places socked by Sunday evening’s LES blast. In the wake of this system, more significant LES will return later Tuesday night into Wed AM. Most models favor enough of a westerly flow to keep the bulk of this LES below the Buffalo Stowns, a trailing short wave might still be able to produce enough backing of the boundary lyr winds to get this stuff close to the Buffalo Stowns…this will bear careful watching, as accumulations in this band will likely be fairly heavy. And after this dies out Wed night, that’s the last we’ll see of LES for at least 5 days, if not longer.
The long advertised temporary moderating trend will set up on Thursday, with rainshowers moving in on Friday. Temps will drop back a bit on Saturday, but all 3 deterministic models show a well organized low coming up the Ohio Valley on Sunday, bringing widespread rain on the currently projected path. After that storm goes by, a colder pattern (not quite as cold as what we’ve been experiencing the last few days) will return for most of Christmas week. It’s a bit out in time, but the GFS and ECWMF both show a weak clipper approaching toward Christmas Eve, and another possibly better organized one behind it by the 26th. So, we may get a thin fresh coating of new snow to cover up the crustier older snow left after the rain.
Buffalo has a 30 year 57% probability of having 1″ of snow on the ground. I’d say our odds this year in the metro area are a little higher than climatology. However, the probability of 5″ or more is 23%, and I’m not prepared to make a call on that one. Some of it will be contingent on how much old snow survives the moderation and rain.
And this week will be no exception. As of this posting (midday Monday), it appears lake effect snow will begin fitfully with some minor amounts this evening, possibly near the metro area for a time, before settling to south of the metro area. On Tuesday, what’s called an anticyclonic curvature will be found in lower level winds, which makes for more drying and sinking motion in the boundary layer at least into early afternoon. When winds back to SW later in the day, ahead of a trough/short wave, lake snow will begin to become better organized…but there still may be some disruptive shear for a short time due to the trough. After a relatively brief visit to the metro area, with some limited accumulation, the axis of the trough will pass and winds will quickly veer to the Westerly flow which sends the LES into Ski Country. Between Tuesday and Thursday, several short waves will traverse the northern Great Lakes, each producing some backing and veering. The amount of backing (which would impact the metro area & possibly NE ‘burbs) is low confidence. The MEAN dominance of the westerly flow is somewhat higher confidence but, as some of you know, that doesn’t tell the whole story. There also will be variations in moisture availability and periods of shear. That means this isn’t going to be a “steady state” singular snow band all the way from Tuesday evening through Thursday. There will be ebbs and pulses, making for extraordinarily difficult accumulation forecasts.
In the extended range, the zonal-ish flow at the 500mb level toward mid-December no longer looks so zonal. The 3 main ensemble means show a rebuilding of the ridge in the eastern Pacific, and some troughing crossing the N Central states and the Great Lakes. The ECMWF and Canadian GEM are strongest with that ridge as we get closer to Christmas. The GFS ensemble is strong with it initially next week, but weakens iT during the 21st-24th. But even the GFS shows heights which would be cold enough to support snow in advance of the holiday. Before we get to that, though, there is good agreement in the medium range of an area of low pressure bringing us some synoptic snow during this next weekend. It may be on the slushy side, and it doesn’t currently look like a blockbuster snow storm, but it doesn’t look like a 90 pound weakling, either.