September, 2012

Ups and Downs, but All in All, an Autumnal Pattern until later in the Month

September 17th, 2012 at 11:59 am by under 4 Warn Weather

At the time of this posting (Monday AM, Sept 17), a beautiful summery day is in progress. A pretty good slug of manageable rain (.5 to isolated 1″ amounts) is on the way, which will begin in the predawn hours of Tuesday. Despite a couple of rogue model runs during the weekend, the heaviest rain–as originally showing in Friday’s model and ensemble runs–will pass to our east into central & ern NY. There may also be a severe weather outbreak on Tuesday in association with strong mid-level dynamics, well to our east and into the Middle Atlantic states. The rain will begin to diminish in WNY behind a cold front by later Tuesday, as temps start to tumble. Wednesday’s cool down still looks notable but it will be short-lived, as warming will develop again by Thur-Fri. That warming will occur ahead of the next reinforcing shortwave which will bring scattered showers by later Friday into Saturday, and renewed cooling. It may be cool enough for a limited lake response on a windy & chilly Sunday. The MEAN pattern will still be for a longer wave trough to impact parts of the east central US and the Great Lakes, with mean temperatures running below average until late in the month, when the pattern will flatten (around the 28th-30th). But within this mean, there will be more ups and downs.

In other words, the basic outlook has not changed from what I’d projected midweek, last week–which in and of itself is somewhat unusual (the consistency, that is). As I’ve noted, while some bloggers’ juices flow in a pattern such as this, September patterns seldom if ever foretell what the winter will be like, and winter outlooks made this far in advance show little statistical skill over flipping a coin. Still, CPC is leaning toward a weak, not a moderate el nino. Weak el ninos (independent of other yet to be determined variables) have been statistically linked with average to below average temperatures in WNY by Robert Hamilton, at the Buffalo NWS.

Some of What I Learned at the AMS Conference

September 3rd, 2012 at 2:37 pm by under 4 Warn Weather

First, a little weather. What was once Isaac looks unlikely to do much in the way of improving the moderate drought conditions north of the srn tier. The best chance for Sct Shwrs & Tshwrs will come on Tuesday, with more concentrated activity possible Well SE of the metro area. Plenty of water vapor will move up to our region by tomorrow, but forcing mechanisms will be weak at best–not much of a trigger. There could be a stray shower or 2 Wednesday afternoon, but that day should be mostly rainfree. A few more showers or tshowers may cross parts of the region on Thursday with the approach of a cool front, but coverage will be sparse. The next best chance for more widespread activity may develop next weekend, as a slow-moving area of low pressure moves east from the midwest. The European appears strongest with this system, and may be overdone…too soon to tell. In the meantime, the next few days will be somewhat muggy.

Notes from the American Meteorological Society continuing ed Broadcast Conference: First, a historical item about Great Blizzards. While we rightfully focus on our ferocious Blizzard of ’77, Boston’s Blizzard of ’78 totally dwarfed our storm for impact (one of the great nor’easters of the 20th century). My longtime friend and colleague, Harvey Leonard (WCVB in Boston), presented a segment on that killer storm. There were 73 deaths, hundreds of coastal homes flooded and/or destroyed by hurricane force winds and storm surge. He showed us an aircheck from the night before the blizzard, in which he virtually nailed the destructive potential of the storm. Over dinner, we talked about the irony in his greatest forecast coming prior to the advent of the higher resolution models and satellite imagery we have available today.

Eliot Abrams of AccuWx made a valuable suggestion for improved terminology regarding remnants of tropical storms and hurricanes. He made the irrefutable point that these remnants sometimes produce highly destructive and deadly flooding, long after wind strength has weakened (as per Irene last year in VT), and that we in the private sector might want to call such remnants (when they pose such a threat) what they are: Tropical Rainstorms. That term might generate more public attention in threatened regions, and I agree.

Paul Gross of WDIV in Detroit presented a case study in which an EF3 tornado struck just north of the Univ of Michigan and Ann Arbor on a day in which NO meteorologist would have suspected a severe weather threat during the morning analysis for the afternoon…lots of damage, and a good reminder that there are still rare cases in which a significant tornado can develop rapidly with little warning.

Storm Prediction Ctr Warning Coordination Meteorologist Greg Carbin presented on several topics. He noted that the initial Local Storm Reports maps many of us look at on the SPC site tend to have many more tornado reports than confirmed tornadoes, and that the Filtered Count can reduce the initial count by 15% on smaller outbreaks and 25-30% on larger outbreaks. One factor is that many reports, even from trained spotters, often come in concerning the same tornado. After this year’s deadly start, we have nearly flatlined before the smaller tornadoes associated with Isaac, and may be on track for the lowest tornado count on record, if we don’t get large autumn outbreaks.

Case studies at the NWS training center in Norman (headed by former Buffalonian Ed Mahoney, Science & Operations Officer at the Buffalo NWS) concerning the use of Dual Polarization WSR 88-D radars show promising improved rainfall accumulation totals, flood warning lead times, detection of debris balls from stronger tornadoes, hail type and size, and precipitation type.

On to Climate Change/Global Warming: The empirical data that global warming is ongoing and that sea levels are rising is absolutely conclusive. The evidence that anthropogenic activity is by far the strongest forcing mechanism in this warming continues to grow even stronger. Climate models, when initialized with all natural forcing mechanisms (including solar input) maxed out and CO2 levels brought back to early 20th century levels show the globe would have been cooling for the last century up to the present time. Climate scientists can find no other explanation for the ongoing warming other than the overwhelming influence of increased CO2.

As predicted by climate models in the late 1980s and 90s, the greatest warming continues over the Arctic region. In general, warming is occurring faster than most models have predicted. The Arctic Ocean is likely to become ice free for 2-3 months by 2030 at the latest, and possibly by late in this decade. This will offer improved navigation for freighters and tankers for a short window. This summer has not been especially warm in the Arctic, but because ice has been thinner when refrozen this decade, it melts more readily in the summer. As some of you have heard, we now have the smallest ice cover in the Arctic since satellite records began in 1979, despite a fairly cool summer at those latitudes.

Ocean acidification from added CO2 continues to amplify as a problem, threatening coral, many shellfish and other species. There are some exceptions…lobsters will probably do better in this marine environment.

Again, I’ll make no remarks on policy changes which are related to dealing with global warming, as that is far outside of my expertise–nor did the presenting scientists. They simply laid out the data.

An interesting side note to last winter’s highly anomalous weather; in a panel discussion with a few truly world class scientists (Kerry Emanuel of MIT and Kevin Trenberth of the Climate Analysis Section of NCAR, to name 2), I asked about the role of the MJO in last winter’s pattern, and whether it might have been a dominant forcing mechanism in defeating typical la nina climatology. I posed the question admitting I had little knowledge about the workings of the MJO. Drs. Emanuel and Trenberth surprised me in their response: they agreed that the MJO is very poorly understood, very poorly predicted beyond a couple of weeks, and that nothing has been published about its possible role in our winter weather. They also agreed with me that newly apparent variables, including Judah Cohen’s hypothetical link with October Siberian snowfall and the AO, along with the anomalous behavior of the MJO, have made winter outlooks even more unreliable than they already had been. For those reasons, I will keep my trap shut about the upcoming winter. I’m not much for pointless exercises.