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After the frosty start to this week, a warm front will arrive in WNY by Wednesday AM, ushering in some Sct Showers & Tstorms. This will be elevated convection, so it will not be impacted by the cooler lake waters. The models for wind directional change with increased altitude show quite a bit of low level veering/wind shear, so some thunderstorms with rotation can’t be ruled out. After one or 2 rounds of Sct convective cells into early Wednesday afternoon, things should settle down for a few days, with daytime highs averaging in the low 70s. The chance for Sct convection will probably return by Sunday into Monday and Tuesday. The airmass at that time will be warm and instability will be on the increase. An upper level trough may take on an orientation (negative tilt showing in some ensemble means) which would increase advection of warm & humid air and help create better dynamics for strong tstorms by Tuesday. A cold upper level low well to the NW of the surface low will feed cold air aloft and create more impressive lapse rates.
It’s VERY early in the game, but this kind of pattern can be recognized as one which can increase the chance for severe tstorms over parts of the Great Lakes.
Our streak of 70+ degree days reached 7 as of Monday, and a few more are likely to keep that streak going. A slow moving storm system over the south will send some very limited moisture into WNY on Wednesday. In the meantime we also had 5 consecutive days with 100% of the possible sunshine 5 days in a row…rare ’round these parts! A few more spotty showers may be around on Thursday and Friday as well. During Saturday, a cold front will drop into the Great Lakes. The rainfall potential with this strong front remains quite uncertain, but Sunday/Mother’s Day will probably be our first day with below average temperatures in 2 weeks. A few showers may pop up with the cold air aloft producing some instability on Sunday, but it should be rainfree most of the time. Sunday night could bring some patchy frost inland IF skies clear enough and winds subside sufficiently. Monday will still be cool, but plenty sunshine will return, and readings will go back to above average by Wednesday. So, this chillier period is going to be strictly a quick hit.
There is no real confidence any longer that early CPC outlooks for a milder than average spring will bear fruit in May. In the near term, although the CPC is giving us a somewhat positive anomaly for temperatures in the 6-14 Day Outlooks, it should be noted that the 3 indices will be trending in the wrong direction for significantly warm anomalies around here. The AO and NAO are both showing most of their ensemble members trending toward negative territory in May, while many PNA members trend upward. While these indices tend to have a little less impact climatologically as we move into mid-spring, this year that may not be so much the case. A major snow cover anomaly continues over much of the northern plains and nearby Canadian praries, assuring a colder pool of air. That, plus a large area of high soil moisture will also hold temperatures down. Whether these anomalies will still play a key role later in May is unknowable right now.
The MJO has become weaker, and its climatological impact also lessens as the month goes on. ENSO remains neutral, and is forecast by most models as likely to stay neutral through the autumn.
While these near term positive temperature anomalies are the first we’ve seen from CPC in probably a couple of weeks for us, the confidence level for both the 6-10 & 8-14 Day Outlooks is only 2 out of 5, and that may be tied partially to the indices’ trends I outlined above.
In any case, CPC has backed off from the weak warm anomaly it had for our region for May, and gone over to EC. And, since ensemble means are showing no rebuilding of an eastern ridge with any staying power in the next 14-16 days, I concur with that call.
After this past week’s soaking rain, I wouldn’t say there’s “no rest for the weary”, but there may not be enough rest. A strong warmup on Monday from a downslope wind will boost temperatures by close to 20 degrees from Sunday’s high. The proximity of a nearby cold front will increase the chance for some showers by Tuesday, but the amount of rainfall we can expect from the passage of that front seems uncertain. Later in the week, the European model brings a deep low pressure system toward the northern Great Lakes. That might warm us up again sharply around Thursday, but the Gulf inflow ahead of its cold front and the dynamics of that storm–if realized–could bring convective rains and the potential for larger amounts. A backslide will arrive by or during Friday to below average temperatures into the weekend. The ensemble means are not showing much in the way of a rebuilding of a warmer pattern afterward, into the following week.
The indices seem to support that cooler pattern again as well, with the AO ensemble trending downward later in the month. The NAO has a lot of spread, but there appears to be a slightly negative mean to the ensemble members. And, there is an upward tick in the PNA members at the very end of the 14 day period.
The anomalous snow cover over the upper plains/upper midwest and Canadian prairies is also serving as an anomalous cold air reservoir for the north central US, and that reservoir can also deliver chilly outbreaks to us–as we already know.
Pretty harsh afternoon for the Dyngus Day parade, with a nasty wind chill, some bits o’ sun, and some occ’l snow showers. The hills well south could see 1-3″ amounts overnight, with a little blowing snow to boot. But there are FINALLY signs of a more fundamental pattern change taking shape gradually later this week and continuing into next week. For example, the European 500mb ensemble mean shows rising heights in the east and falling heights in the interior of the west. This would allow temps to approach age at the end of the week and to run somewhat above average much of next week. There’ll be some ups and downs here and there, but MEAN is changing. Average high for today is 48
As forecast last week, conditions this week are a good deal less harsh. But daytime highs will continue to run below average for the remainder of the work week, with a temporary moderating trend during the weekend. The North Atlantic block which has forced the polar jet stream to buckle to the south from the northern plains to the mid-south and up through the interior of the NE is weakening, but not entirely dissipating. Some nuisance snow showers will show up Wednesday into Thursday. The high angle of the sun will likely mix the snow with some rain during the afternoon at lower elevations. After high pressure moves in to bring us a pleasant Saturday, a warming downslope breeze will develop Saturday night into Easter morning ahead of another cold front. While temperatures will move above average for much of Easter, rain showers will develop by afternoon. After that sharp cold front goes by, however, we take 2 steps back with a gusty wind and falling temperatures on Monday–and the redevelopment of snow showers. No major storms are in sight, but we’ll have to keep an eye out for lapse rates/instability over the Lakes early next week, as some lake effect cannot be ruled out. Temperatures will run below average during the work week.
In the longer term, ensemble means (European, GFS, and Canadian) all seem to show more “tolerable” temperatures further out in time. There are still no signs of a fundamental shift to a western trough/warming eastern ridge, but the flow does seem to become nearly zonal in the mean. This would allow temperatures to be closer to average. The MJO is favored to become somewhat less active, which would favor greater variability over the North Atlantic (source: CPC), and the AO and NAO stay negative, but at much less amplitude. The PNA is looking to be more neutral. In the mean, it looks like a flatter pattern. However, interactions with individual short waves–as always–cannot be seen in this time range.
Foreseeable future usually means 16 days or so, which is the range of global models and ensembles put into everyday use by operational meteorologists. But as I mentioned Monday evening on the air, 7 or 8 days prior to Sunday’s 65 and Monday’s 63, temperatures in that range simply were not detectable in operational models or ensembles. With that caveat in mind, there is no sign now that 60s will be returning in the “foreseeable range” out to March 25th or so.
Readings will seem dramatically colder after these 60s, but will not be unseasonably cold statistically. Some snow showers will be likely to develop Tuesday night but more likely on Wednesday and Wednesday night, when some spotty minor accumulations will be possible on the hilly terrain. By Saturday, something of an Alberta clipper may bring us some wet snow or a mixture before giving way to slightly colder air again (and drier conditions) on Sunday. So, neither parade will be basking in the incredible warmth we had last year for the St. Patrick’s weekend.
There are mixed signs of a storm system in some models and ensembles for around the Tuesday-Tue night time frame, but there is far too much disarray in that guidance for any confidence on storm path, intensity, or p-type–if it gets here. Most of what evidence there is suggests rain ending as snow rather than a snow scenario, with the operational Euro the deepest of the models, with the most potential for stronger winds behind the storm. Some guidance has a far flatter system, and some members have what there is of it miss us, so it’s absolutely premature to get excited as of this posting–Monday night.
As of midday Monday, most computer guidance tends to favor mixed precipitation rather than all snow for Tuesday night. But note I said “tends”. There is still a chance enough vertical velocity/lift may occur Tuesday night to cool our atmosphere over portions of WNY to convert a mixture to a period of heavy, slushy snow. The probability of that occurring is, in my judgment, less than 50% but far from an insignificant probability. If that changeover occurred, with fairly gusty winds, the accumulating slushy snow could bring down a few tree limbs and powerlines. The 12z NAM, in particular, has some pretty good lift Tuesday night for such cooling. Wednesday’s rates of precipitation look a little less impressive in the NAM, with reduced lift, that the Wed AM period in the GFS. Still have to view the next run of SREF output.
After that, the pattern I’ve been advertising for a long time still is on. Largely dreary and chilly, sometimes just plain Cold. There are signs that weekend highs may just be in the 20s, which is colder than last weeks ensemble means were suggesting. Another storm may move off the NE coast by then, but this one looks to be too far to the east to have a direct impact here with snow.
After something of an Arctic Blast with some limited lake snow, temperatures will begin to moderate on Friday. Some light snow may approach by late in the day, and there could be a bit of a light mix on Saturday, with a few degrees cooling on Sunday behind a weak low. Temps will moderate again on Monday, but there are signs this warm up will be short-lived. However, the colder air returning by Tuesday or Wednesday next week looks seasonably chilly, rather than true continental polar air.
The overall storm track will remain somewhat active, with a significant severe weather threat by Thursday this week in the southern plains and Gulf states, and possibly some more storminess again next week. But there aren’t many signs that our region will be under strong influence of any nor’easters at this time. That’s not to say it won’t happen…it’s just that there are no defined signs of it as of this Tuesday posting.
It appears that a northerly flow will keep our temperatures seasonably chilly in the first week of March. Most ensemble means have the axis of a trough in the NE, a little too far east for any nor’easters this impact us. But that IS a long way off. I’m more confident about somewhat below average temps in that period than I am about the lack of storminess for WNY.
No time for great detail on this busy Wednesday evening, but a widespread Winter Storm still appears likely to deliver its heaviest snow to the Niagara Frontier, with somewhat lesser amounts to the south. There is still the question of how much–if any–of an icy mix may develop to the south of the metro area Friday, which would hold down accumulations but make travel more treacherous. There is also the question of a cutoff time to the heavier snow as of this posting, with the NAM and our Vividcast quite a bit faster than the GFS. Most models now are not showing full tilt snowfall rates until we’re into the Friday AM commute, rather than in the predawn hours. If that trend holds true, it’s going to make school delays and cancellations a more difficult call. The wind will be sufficient to cause some Blowing Snow, but currently appears below the threshold for full whiteouts, unless the snow is truly coming down VERY hard. (It will be a different story in NYC-Boston, where the coastal storm will develop powerful gusts by later Friday into Saturday AM, resulting in a Blizzard Watch for Boston to Providence.) If the operational GFS were looking to be a best bet, then I’d have to raise my earlier preliminary estimate for the Lk Ontario counties above the 8-12″ in my early evening forecast. Still working on that, and have to see the next set of SREF output.
Another coastal development may bring more snow to our region and parts of the NE around Thursday next week.