Updraft: April 4, 2012 Archive

Was record March "Warm Wave" predictable?

Posted at 12:00 PM on April 4, 2012 by Paul Huttner

90+ cities set records for the warmest March ever in 2012

"We will also demonstrate, using seasonal climate forecast models, that the circulation pattern and the associated heatwave was remarkably predictable at long lead times, from initial atmospheric conditions at about 1 February 2012. This fact also gives important further clues on the leading processes responsible for the heatwave. Importantly, the meteorological conditions associated with the heatwave had an appreciable, and perhaps unusual, long-lead predictive element."

-NOAA's Environmental Systems Research Laboratory on the predictability of the record March 2012 heat wave.

NOAA's CPC called for above average temps in March 2012 in the Upper Midwest. But how well could we have predicted the magnitude and coverage of the record March 2012 heat wave?

An eye opening report from NOAA's Earth Systems Research Laboratory says there were signs that could have better predicted our "off the charts" March this year.

Here are some excerpts from NOAA's report.

1. What were the meteorological conditions associated with the heatwave?

"It is first useful to place the heatwave into a Northern Hemisphere context (Fig. 1). The heatwave was clearly regional in scope and was not part of a pervasive hemisphere-wide warm regime. Rather, widespread cold conditions at the same time occurred over the western U.S., western Canada, Alaska, eastern Asia, and southeast Europe."

Figure 1: Map of Northern Hemisphere temperature anomalies averaged over the period. Anomalies are calculated relative to the period 1981-2010.
[Data Source: NCEP/NCAR Reanalysis]

"The very warm air first pushed northward west of the Great Lakes region, and subsequently spread eastward. This synoptic view is consistent with structural aspects of the atmospheric circulation, shown in the Physical Processes section, that reveal intense poleward air mass movement propelled by an unusually intense low level southerly jet that stretched from Louisiana to western Wisconsin. Once this warm surge inundated the area, a remarkably prolonged period of record setting temperatures ensued. These time series thus identify a core period of the maximum heatwave intensity that spanned roughly 12 March thru 23 March, a period for which we will perform various time averaged analyses."

One interesting finding in the report is that it appears that the warm air surge drove the erosion of snow cover from the Upper Midwest in March...not the other way around.

In other words, the lack of snow did not cause the warm up...the warm air surge from the south caused the snow to disappear!

Climate Change signal?

Did climate change and greenhouse gasses play a role? According to the report, GHG may have increased the likelihood of a record event by anywhere from 5% to 10% over the "background" warming trends already in place at the time.

3. Was this extreme March 2012 U.S. heatwave event anticipated?

"Here we explore the evidence for a substantial human influence on the March 2012 heatwave, both on its magnitude and on the probability of such an extreme event occurrence. There is no doubt that there exists an influence of human-produced greenhouse gases on evolving weather and climate conditions, as the IPCC reports have clearly enumerated. Yet, while acknowledging that climate change plays a role in every weather event begs the issue of the direction of that impact and the magnitude of its effect. Unfortunately, when claims are made that a event "would not have happened without human produced greenhouse gases", the incorrect conclusion is all too often drawn by the public and media that an event was caused, in some de novo manner, by human climate change. The pitfall of such framings is apparent from the well-known nature of chaotic weather and climate systems. In that paradigm of a nonlinear system, no event today or tomorrow would have happened owing to the smallest flap of a butterfly's wings. But is there any predictability, and in particular, could the March 2012 heatwave have been anticipated?"

"The sudden change in location and in magnitude of warming, as anticipated by February initialized forecasts ,reveals the role of an emerging state of internal atmospheric variability. This change is irreconcilable with changes in GHG forcing whose time scale is far too long, and whose influence would have been very similar in the prior initialized forecasts. What is also striking is that the 40-run ensemble mean magnitudes were on the order of +4°C for the monthly March average, which equates to about 2 standardized departures in the forecasts. One can repeat the analysis of how such a magnitude signal (in this case, the signal of the climate prediction rather than the projection) altered the odds for a 2 standardized (i.e. ~4°C) March heatwave. Such a major shift of the distribution in the CFS implies a roughly 10-fold increase in the probability of such a heatwave occurring.

A black swan most probably was observed in March 2012 (lest we forget 1910). Gifted thereby to a wonderful late winter of unprecedented balmy weather, we also now know that all swans are not white. The event reminds us that there is no reason to believe that the hottest, "meteorological maddest" March observed in a mere century of observations is the hottest possible. But this isn't to push all the blame upon randomness. Our current estimate of the impact of GHG forcing is that it likely contributed on the order of 5% to 10% of the magnitude of the heat wave during 12-23 March. And the probability of heatwaves is growing as GHG-induced warming continues to progress. But there is always the randomness."

The bottom line?

Greenhouse gas "loading" of our atmosphere makes it more likely that more record heat waves will occur. Initial conditions leading into March suggested that a heat wave was more likely, but even the most extreme forecasts did not predict the magnitude of last month's record event.

This paper strikes me as important because if we can latch on to those signals that caused the March heat wave...we may be better able to predict future extreme weather events.

PH

Whitish tinted sky may be smoke from distant fires

Posted at 5:15 PM on April 4, 2012 by Paul Huttner (2 Comments)

+10 degrees vs. average again Wednesday in much of Minnesota

52 average high for MSP Airport

60s the rest of this week

Smoke from distant fires (and cirrus clouds) combining to produce white tinted sky over Minnesota?

Vivid sunsets this week due to fire smoke?

MNDOT traffic cam shows whitish sky over Minneapolis Wednesday.
Source: MNDOT

Smoky skies?

You may notice a whitish tint to the sky this week over the "Land of Sky Blue Waters."

A thin veil of cirrus clouds wafted over Minnesota Wednesday, but an assist may go to elevated smoke from distant fires to produce our whitish tinted sky over Minnesota this week.

According to the web site U.S. Air Quality, fires from Kansas & Colorado & the northern Rockies to as far away as Central America may be sending a veil of smoke over Minnesota this week.

"Beginning as early as sunrise, the HMS team also reported a moderate-to-heavy dense region of smoke/dust over the midwest. Concentrated over eastern Iowa and central Illinois, the plume was progressing sluggishly to the north and east as a low pressure system with its counterclockwise southwest wind flow approached the affected area. The HMS smoke analysis superimposed with NASA's GEOS-5 model Total Aerosol Optical Thickness (AOT) forecast indicated elevated AOT aligned with the moderate/heavy smoke (bottom left). In addition, there were reports of light smoke stretching from Missouri to Texas, an area that also experienced raised AOT.

NOAA's hazard mapping system has identified the haze as smoke. The NRL model predictions are showing additional smoke coming up from Central America and clearing of land is a major source of smoke in spring in Mexico, Guatemala and Nicaragua."

The smoke particles may bounce and scatter the light from the setting sun to produce some vivid reddish sunsets this week!

Forecast: Classic Spring

Source: Twin Cities NWS
(Click to enlarge)

More classic spring weather is the rule this week.

This is one of those classic Minnesota weather patterns that gives us reason to live in the Land of 10,000 Lakes! Cool crisp mornings and generally sunny milder afternoons will stay with us through Friday.

The next rain chance moves in Saturday, but looks fairly light at this point.

What we need is a good, slow moving low pressure system to sit over Minnesota for about 3-4 days and just dump 3-4 inches of rain on the area.

I don't see that just yet, but the GFS is hinting at the potential for some soaking rains as we approach next weekend, April14th & 15th. Yes, the (weekend) timing could be better, but we desperately need some serious rain.

Source: NOAA

Weather fingers and toes crossed!

PH