From the Monday afternoon vantage point: With fairly moist air in place, an upper level disturbance will trigger spotty showers & tshowers, becoming more numerous later in the day. The best chance for this convection will be over the hilly terrain S & SE of the metro area. The atmosphere will remain somewhat unstable overnight, with the approach of the now infamous (polar/nonpolar) vortex, so a few more showers & tshowers may still pop up. On Tuesday, temperatures will run below average, as that vortex increases its influence. Some scattered showers & tshowers will pop up occasionally. The stiffening breeze will put a chill in the air. Most computer guidance shows drier air in place by the time of the Canalfest Parade. However, when you have a cold upper disturbance over warm lake water, I can’t rule out a few lake induced evening showers. The coldest air will be in place midweek. The difference in temperature between 72 degree Lake Erie and the atmosphere about a mile up will cause some lake effect clouds and showers to pop up, mainly over the interior, on Wednesday. Thursday should be mainly dry, and temperatures will begin to moderate more noticeably by Friday. There is considerable uncertainty about shower chances for coverage and timing on the weekend. At this point, there are no indicators of a complete washout on either day, but some showers & possible tshowers will probably push into WNY on Saturday from the south. The best chance for the most activity currently appears to be to the south of Buffalo. And early signs favor less activity–if any–on Sunday. Monday also currently looks to be dry. Temperatures should be closer to average Friday-Sunday, and may edge up to above average by Monday.
In case anyone didn’t notice, there is plenty of water vapor in the atmosphere this afternoon, and plenty more to come into Tuesday evening. The Storm Prediction Center has WNY & northern PA at Slight Risk for Severe Tstorms with damaging gusts. However, the abundant cloud cover has held down heating. That, combined with the stiff Lake Erie wind is keeping the atmosphere less unstable across the Niagara Frontier thus far. Any stronger storms which develop later today would be more likely Well S & SE, away from the lake’s influence. The humidity stays high tonight, with the best chance for scattered showers & TStorms in the early evening. On Tuesday, chances for showers & TStorms will be greater in the afternoon. SPC again has much of our region at Slight Risk for Severe Tstorms, but that risk appears mainly south and east of Buffalo, rather than closer to Lake Erie. Behind a cold front, humidity will drop back on Wednesday, even though a disturbance may yet kick off a few garden variety showers. A dry air mass will then stay in place Wednesday night into Saturday. Thursday will be seasonably cool, with readings edging up Friday & Saturday. By Saturday night or Sunday, an approaching disturbance will probably bring a few rounds of showers & tshowers across parts of the region. Timing and coverage remain quite uncertain at this point. Another cold front will be approaching late in the weekend, with readings dropping back early next week.
No extreme heat is in sight. The upper air pattern will favor troughing redeveloping over the Great Lakes from time to time, with the mean expressing that troughing. Currently, there are also no indications of extensive warm ridging near us in the next 16 days. However, there are no indications of lengthier cool and wet periods either. For agricultural purposes, precipitation should be sufficient to avoid frequent reliance on irrigation.
while they’re fresh in my mind:
Earlier estimates of a Strong or even Super El Nino appear to have been overdone and overblown. Newer model data suggests a Moderate or even Weak El Nino, which makes a difference. Every El Nino episode is different. In general, however, Moderate or Weak El Ninos taken by themselves have not been shown to necessarily correlate to a milder than average winter in our part of the country, while especially Strong El Ninos do appear to have such a correlation. So, it may take other variables in our atmosphere to produce a milder winter, none of which is predictable at this time (we had a number of experts in this field address us at the conference).
The danger of hyperthermia/heat stroke/death of children left in cars is even greater than you may have heard. Color of car makes no real difference, nor does “cracking a window”, and such deaths have been increasing even at more northerly latitudes. Here is the report from Jan Null, AMS Certified Consulting Meteorologist of San Francisco State University, written for laypeople: http://www.ggweather.com/heat/
-Beware of Alarmist Gibberish from unqualified Facebookers & other Social Media, presented by my scholarly friend Dan Satterfield: http://blogs.agu.org/wildwildscience/2014/01/31/the-great-facebook-blizzard/
-Future Weather Warnings may have more clarity, and less confusion…but it will take a while. The current list of color codes and warning/advisory criteria by the National Weather Service has become all but overwhelmingly confusing and difficult to digest on busy weather/severe weather days. The British Met Office has had great success with simplification by presenting Public Impact colors–just 3– ranging from Yellow (Be Aware) to Amber (Be Prepared) to Red (Take Action). While our weather is often more complex and severe than that of Great Britain, even Storm Prediction Center expert Greg Carbin has been impressed by these ideas from our friends across the sea. The watches, warnings, and advisories will still have to be fitted to individual threats, but the Public Impact color code is being examined by NOAA, the NWS, Emergency Manager organizations and others. The Met Office presentation was well received: http://www.metoffice.gov.uk/public/weather/warnings/#?regionName=uk&tab=map&map=Warnings&zoom=5&lon=-3.50&lat=55.50&fcTime=1403409600
There is some debate on the rate of current and future global warming, but evidence remains extremely strong that human activity is the primary forcing mechanism for the ongoing warming (which is currently focused more in the oceans than in the atmosphere, along with increasing rates of acidification–a danger to coral and many shellfish–due to increased amounts of carbon being absorbed by the oceans). Sea levels continue to rise, more than 90% of the earth’s glaciers are in retreat, and CO2 is at its highest level in at least 850,000 years, 400 parts per million, compared to 280 parts per million prior to the industrial revolution (up 40% from those levels). Due to continued industrial growth and building of coal fired power plants in nations such as China & India, CO2 emissions are likely to continue to rise rapidly. As I’ve frequently posted, one of the best sites for those who want to learn more about these topics is: http://climate.nasa.gov/
-It was a great conference, held in Squaw Valley CA, by Lake Tahoe…and a terrific learning experience. Thanks for WIVB/WNLO Lin Media for allowing me (and other LIN meteorologists) to take in this valuable continuing education.
The links in this text appear in usable form in the first comment below.
After Saturday’s crisp and comfortable conditions, warming will resume on Sunday and continue to build for a good part of the week of the 16th. An upper level ridge will strengthen in the east until later in the week. Around the periphery of this ridge, several short waves will cross the Great Lakes and bring several rounds of Showers & Tshowers. The humidity will begin to build noticeably on Monday and hold into at least midweek. There is relatively good agreement in the ensemble means that some degree of troughing will redevelop near the Great Lakes later in the week, allowing more comfortable conditions to return. At this point, this cooling doesn’t appear to be likely to bring below average temperatures for any extended period. More seasonable temperatures will prevail in the mean. It can’t be determined if this weaker troughing might continue a parade of occasional short waves or not. After the early ridging during the week of the 16th, the rest of the means either favor a zonal flow or a slight WNW flow with the weaker troughing, with no visible rebuilding of the eastern ridge.
On the matter of El Nino, there continues to be some disagreement between the more conservative forecast offered by CPC on the amplitude of the event, compared to the NASA link we’d posted earlier, and some other projections. At the current time, the positive sea temp anomalies have some similarities to those observed in June 1997. However, there has also been Kelvin wave activity which has produced some of this warming. Owing to the ENSO ensemble members I’ve seen, there are only a couple of the many members which bring amplitude beyond 1.5 degrees positive anomaly. That is, most members project a Moderate El Nino. The correlation between a Moderate amplitude and WNY winter positive temperature anomalies is much less so than in the case of a Strong el nino. The hopelessly tired cliche “time will tell” applies here. We’ll have to continue to monitor the ENSO ensemble over the next several weeks to see if the trend changes.
As we’re now into the warm weather season, the surface features on the weather map tend to be flatter and weaker, as do many of the mid-level features aloft. In other words, timing weaker more subtle systems makes for some challenging forecasting. That doesn’t mean ALL systems are weak and poorly defined. In fact, as I type this post conditions look favorable for a rather major Severe Weather Outbreak on Tuesday the 3rd over portions of Iowa, Minnesota, Nebraska, NE Kansas and west central Illinois. But in the mean, defining troughs and ridges in the 500 mb flow, properly placing them, and properly determining their strength/amplitude becomes tougher. That’s because the mean tends to produce more of a zonal look. That’s in contrast to the blocky, high amplitude pattern we had so often until recently.
And remember, this mean is often the smoothed mean of many ensemble members in the global models which have a lot of spread between one another. The mean can be a best choice by default. But it is not necessarily the most reliable choice.
There will be a cooldown with reduced humidity returning toward Wednesday morning. Almost immediately afterward, there is already low confidence as to when any showers associated with an area of low pressure going by to our south might arrive in parts of WNY, with 2 operational models bringing those showers back in by mid or late Wednesday afternoon. Odds do favor much of the rain with that system staying farther south. The GFS is blindingly fast with onset and exit times, and viewed with suspicion on that speed. After lovely and dry days on Friday and Saturday, during Sunday another area of low pressure will be approaching, probably bringing some convection in by later in the day, with a few more rounds into Monday AM. There are no signs of prolonged heat and humidity, nor are there signs of prolonged cool weather. So, at this point, much of this next weekend looks pleasant. But unlike the last 2 weekends, the finish to the weekend is in doubt.
There are no changes to the ENSO forecast this week. The so-called key Nino Region 3.4 has a +.6 degree positive SST anomaly. Generally, an el nino is not considered as such unless there are 3 consecutive months of el nino conditions. A couple of weeks doesn’t cut it, partially due to the rising and ebbing warming/cooling caused by Kelvin waves traversing the Pacific. I’m still seeing only a handful of ENSO models projecting a truly strong el nino. Many, including the mean of the CFSv2, lean toward a moderate el nino.
At mid-latitudes, we are still in something of a “blocky” pattern. A warmer ridge of high pressure will briefly peak aloft on Tue-Wed, followed by a large upper level low forming well to our NE by later in the week. That almost-cutoff low will usher in a return to below average temps for Thursday-Friday. However, it will gradually relax its grip during Saturday, allowing milder temperatures and dry air to move in for Sunday and Memorial Day. The overall 500 mb flow in the ensemble means favors above average temps much of the time next week, with an uncertainty concerning precipitation potential.
Even this week, as we draw closer to the long advertised rounds of scattered convection which arrive late Tuesday into Wednesday, precipitation potential has uncertainty. The amount of precipitable water in the lower atmosphere will be high, but the triggers for organization don’t look impressive. There may be a couple of isolated downpours. In addition, a couple of models suggest a convective complex could come riding down on a NW flow into NW PA toward Wednesday AM, which would pose a risk of heavier rainfall close to Chautauqua County, and stronger winds. Our in-house models don’t see this potential as of this posting (Monday evening). Even during our Tue-Wed moderating sfc flow, local Lake Erie shoreline/waterfront temps will remain below average–so this isn’t much of a warmup. After a Thur-Fri with high temps in just the low 60s, and a few leftover light showers possible, Saturday should bring high temps in the upper 60s inland with only a small chance of a couple of deep interior light showers. Sunday and Memorial Day look spending, with Monday being the warmest of the 3 days.
Odds for El Nino will continue to increase by early summer, and will approach 80% by autumn in CPC’s newest perusal of ENSO models from around the globe. As I’ve already mentioned in the previous thread, a summertime el nino has little if any effect on our regional weather. And, as most of you know, its impact on our cold weather months seems to be keyed to the amplitude/strength of el nino. Some researchers are suggesting evidence is growing for a strong el nino. Model ensemble members are more of a mixed bag on strength. In my judgment, uncertainty on strength remains fairly high.
A wavy cold front will be in WNY by Wednesday and may provide a pathway for a few waves of low pressure. Depending on the precise path these waves follow, locally heavy to excessive rain could reach parts of WNY by late Thursday into Friday AM. Preceding that, we’re likely to have several rounds of Showers & Tstorms, with abundant rainfree time. There are no current signs of an organized severe weather outbreak in our region. But just this Monday evening something of an unexpectedly ferocious, small outbreak developed in NE Ohio. With abundant water vapor in the air (precipitable water) and occasional small impulses of vorticity crossing our region, isolated strong to severe storms cannot be ruled out. The muggiest day of this stretch will probably be Tuesday, when interior high temps could reach or exceed 80. Unlike last week’s 82, this time the dewpoint will be higher, making things feel stickier.
Again, the exact placement of this cold front will be critical to total rainfall potential, as well as temperatures. Wednesday may be a few degrees cooler, but the warm, humid airmass may stay in place east & SE of the metro area, on the warmer side of the front. After the heavier rainfall pulls off to the east and the front passes farther to the east, temperatures will be much cooler (as forecast since last week) for several days. Soaking rain MAY still be with us Friday AM, but should be diminishing from W to E. Friday’s high temps will be in the mid-upper 50s. Saturday will be a little unsettled and cool with a few sunny breaks and a few showers. High temps will again be well below average…mid-upper 50s. Sunday looks brighter and drier, with a high near 60. There is good agreement in extended range guidance that temperatures will be heading back to above average by Wednesday or so next week, as upper level ridging rebuilds and gives us at least several warmer days.
The warmup we advertised all last week for later this week is still on the way, along with some Scattered convection at times. So, the “big picture” hasn’t changed much. As for details, the approach of a warm front midweek will probably set off some weak convection by late Wednesday, picking up at times Wednesday night into portions of Thursday. The proximity of this front and some elevated instability (bubbly air aloft out ahead of the warm front) will probably fuel a few of these tshowers. In fact, by Thursday afternoon and evening, our surface airmass will take on an “Almost Muggy” feel, with daytime highs in the 70s and overnight lows from the upper 50s to near 60–accompanied by higher dewpoints. The timing for actual warm frontal passage is still in question on this (Monday) evening. Once we get into the warm sector and that boundary has passed to the N & E of us, activity will slacken. As we move into Saturday, a wave or 2 will move up along a cool front and bring us a few rounds of showers & possible tshowers Friday night into portions of Saturday. There are signs much of this moisture will pull off to the east Saturday evening. On Sunday, the Canadian GEM is an outlier with a short wave bringing a return of showers for part of the day. But both the GFS and ECMWF seem to keep us mainly dry and seasonably mild Sunday. Monday becomes more of a question mark. The ECMWF rebuilds a strong ridge in the east, which blocks the approach of a cold front and its convection until Wednesday PM-Thursday, while the GFS brings some convection back to WNY as early as Tuesday or even later Monday night. Right now I’m leaning toward the ECMWF and its ensemble mean, but confidence remains shaky at best (both periods in the CPC outlook are of Below Average confidence — 2 out of 5), so I know I’m not alone in eyeing this model and ensemble disarray warily.
The ensemble means do bring some troughing back closer to the east central or eastern US between the 14th & the 16th, which would drop temps back below average for a few days. The ECMWF mean flattens the flow later in the period, while the GFS takes longer to show a zonal flow. Again, the zonal depiction late in the period may possibly be tied to the smoothing of the wide spread between ensemble members, rather than a realistic representation of a zonal flow. That idea doesn’t necessarily mean the troughing will persist. The ensemble member spread could also hide some modest return to western troughing and eastern ridging…too early to tell.
and that often leads to an unpromising pattern, depending upon what part of a block you find yourself under. In this case, there are signs of a near cutoff low getting closer to us by April 29-early May, and those signs are strongest in the ECMWF mean. If we were to get stuck in the “sweet spot”, a cutoff ridge, that would be a good thing. At this early juncture, that appears less likely than being near a cutoff low moving from the central US to near the Great Lakes. Cutoff systems are those which are cutoff from the higher speed westerlies which keep weather systems moving along. Late April-mid spring is the time when cutoff systems become more climatologically favored. The synoptic weather traffic jams can sometimes impact many parts of the mid-latitudes and northern latitudes.
When we’re stuck under a cutoff low, a lengthier dreary and cool pattern can result, with some showers from time to time. The GFS is also showing signs of this blocky pattern, with the Canadian less so inclined. This is the first time this spring I’ve seen the ECMWF ensembles so strong on a cutoff, so this will need to be watched carefully. For now, I’m not taking this a good sign for the extended range.
In the meantime, cooler weather will arrive Tuesday with mostly AM showers, and then another round of lighter showers Tuesday night which could be mixed with a few wet snowflakes toward Wednesday AM at the highest elevations. Wednesday will be chilly, with some sun returning by afternoon, and Thursday will be dry and sunnier with seasonable temps. Friday will be milder but wetter with some rounds of showers, followed by a damp, cool Saturday with falling temps in the afternoon–though not much accumulating rainfall. Sunday looks chilly (upper 40s) with limited sun and mostly dry conditions, though a few light showers or mixed showers can’t be ruled out. There should be some moderation early next week before the approach of any cutoff low later in the week.
This week will again present us with ups and downs, and a fairly typical early spring lack of consistency. After a Very Wet Monday evening, drier conditions will set in for the midweek with below average temperatures giving way to above average on Thursday, slipping a few degrees on Friday, and coming back above average during the weekend. One feature this spring which has not yet plagued us it the “cutoff low” in a blocking pattern. These tend to become more common in climatology as we move a little closer to mid-spring, but there are no signs yet of such a development in the next 14-16 days. So, there’s THAT–at least. Of course, in a block, you could also get under the ‘sweet spot’, the blocking ridge. THAT would be a good deal. No signs of that either.
Ensemble means (I’m relying on them more than operational models) continue to show those ups and downs into next week. By April 17-19, a flatter zonal flow shows up in the means. However, some of that flatter, low amplitude flow shows up because of the huge spread between ensemble members farther out in time. That is, the members and models cannot see short waves, their amplitudes and their paths so far in advance. When the spread between ensemble members is very large at the 500mb height level, the mean tends to be flatter. It’s a statistical compromise which has little to do with actual predictions for amplitude and teleconnections. What’s been happening so far this spring is a tendency to return to ups and downs the closer we get to the ensemble means prediction of a flat, zonal flow…as soon as the members and the models are able to “see” the short waves and the wavelengths between ridges and troughs. We’re certainly out of the extremes of winter, but for the umpteenth blog thread in a row (or so it seems), I still see no sign of a lasting pattern shift to a western trough/eastern ridge.
There are smaller uncertainties about this weekend and the timing for showers either Sunday night or Monday or, if the GFS 18z run were to be believed, showers during Sunday. There will be a transition back to Below Average temps for several days next week. Showers will again cross the region by Thursday night, exiting by early Friday. The weekend is not a lock for Sunday staying dry, but temps both days should be above average…unless 18z GFS (with the GFS’ inherent fast bias) wins out on Sunday and gets those showers and a trailing cold front in here and beats the slower ECMWF.