Posts tagged NOAA
T-Storms High gusty winds headed to Boulder: Prepare to Evacuate
Jun 27th
But this could back fire and drive fire fighters out of Shanahan ridge. Fire could destroy that entire area in the next three days. Below , weather report from NOAA does not bode well for Boulder. We are in a Red Flag warning high fire state. It would be prudent to pack your entire home if you live in Shanahan ridge area. You could lose it all.
...RED FLAG WARNING IN EFFECT FOR THE FRONT RANGE FOOTHILLS AND
SOUTH PARK IN PARK COUNTY FOR SOME DRY THUNDERSTORMS PRODUCING
WIND GUSTS TO 45 MPH FROM NOON TO 8 PM MDT TODAY…
THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST AND NORTH CENTRAL
COLORADO.
.DAY ONE…TODAY AND TONIGHT
INCREASING CLOUDS OVER COLORADO AT MIDDAY WILL SPAWN SCATTERED
THUNDERSTORMS IN THE MOUNTAINS AND OVER THE FRONT RANGE FOOTHILLS
THIS AFTERNOON. SOME OF THESE STORMS WILL PRODUCE STRONG AND GUSTY
WINDS AND FREQUENT CLOUD-TO-GROUND LIGHTNING. WHILE OTHER STORMS
MAY DEPOSIT UP TO A QUARTER INCH OF RAIN IN LESS THAN 30 MINUTES.
THUNDERSTORMS ARE THEN EXPECTED TO MOVE OUT OVER THE NEARBY PLAINS
WHERE THEY MAY PRODUCE SIMILAR WIND GUSTS AND DANGEROUS LIGHTNING.
HOWEVER…STORM COVERAGE IS NOT EXPECTED TO BE AS GREAT AS THAT IN
THE HIGH COUNTRY. MOST OF THIS STORM ACTIVITY SHOULD DIMINISH
LATER THIS EVENING.
OTHERWISE..SLIGHTLY COOLER TEMPERATURES AND HIGHER HUMIDITIES ARE
ON TAP FOR THE OUTLOOK AREA TODAY. A WEAK COLD FRONT BACKING INTO
NORTHEAST COLORADO EARLY THIS AFTERNOON WILL BE RESPONSIBLE FOR
SOME OF THE COOLING ON THE PLAINS.
Five Day Weather Forecast FOR BOULDER
This Afternoon: Scattered showers and thunderstorms, mainly after 3pm. Mostly cloudy, with a high near 94. Southwest wind 9 to 13 mph becoming east southeast. Winds could gust as high as 17 mph. Chance of precipitation is 40%.
Tonight: Isolated showers and thunderstorms before midnight. Mostly cloudy, with a low around 65. South southeast wind 6 to 14 mph becoming west northwest. Winds could gust as high as 20 mph. Chance of precipitation is 10%.
Thursday: A 10 percent chance of showers and thunderstorms after noon. Mostly sunny and hot, with a high near 97. West wind between 10 and 13 mph becoming light. Winds could gust as high as 17 mph.
Thursday Night: A 10 percent chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 63. West wind between 5 and 10 mph, with gusts as high as 16 mph.
Friday: A 10 percent chance of showers and thunderstorms after noon. Mostly sunny and hot, with a high near 97. West wind around 5 mph becoming calm.
Friday Night: A 10 percent chance of showers and thunderstorms before midnight. Partly cloudy, with a low around 65.
CU Boulder — LA air pollution has a surprise problem
Mar 2nd
comes to some types of air pollution
The exhaust fumes from gasoline vehicles contribute more to the production of a specific type of air pollution — secondary organic aerosols — than those from diesel vehicles, according to a new study by scientists from the University of Colorado Boulder’s Cooperative Institute for Research in Environmental Sciences, or CIRES, NOAA’s Earth System Research Laboratory and other colleagues.
“The surprising result we found was that it wasn’t diesel engines that were contributing the most to the organic aerosols in L.A.,” said CIRES research scientist Roya Bahreini who led the study and also works at the National Oceanic and Atmospheric Administration’s ESRL. “This was contrary to what the scientific community expected.”
SOAs are tiny particles that are formed in air and make up typically 40-60 percent of the aerosol mass in urban environments. This is important because fine-particle pollution can cause human health effects, such as heart or respiratory problems.
Due to the harmful nature of these particles and the fact that they can also impact the climate and can reduce visibility, scientists want to understand how they form, Bahreini said. Researchers had already established that SOAs could be formed from gases released by gasoline engines, diesel engines and natural sources — biogenic agents from plants and trees — but they had not determined which of these sources were the most important, she said.
“We needed to do the study in a location where we could separate the contribution from vehicles from that of natural emissions from vegetation,” Bahreini said.
Los Angeles proved to be an ideal location. Flanked by an ocean on one side and by mountains to the north and the east, it is, in terms of air circulation, relatively isolated, Bahreini said. At this location, the scientists made three weekday and three weekend flights with the NOAA P3 research aircraft, which hosted an arsenal of instruments designed to measure different aspects of air pollution.
“Each instrument tells a story about one piece of the puzzle,” Bahreini said. “Where do the particles come from? How are they different from weekday to weekend, and are the sources of vehicle emissions different from weekday to weekend?”
From their measurements, the scientists were able to confirm, as expected, that diesel trucks were used less during weekends, while the use of gasoline vehicles remained nearly constant throughout the week. The team then expected that the weekend levels of SOAs would take a dive from their weekday levels, Bahreini said.
But that was not what they found.
Instead, the levels of SOA particles remained relatively unchanged from their weekday levels. Because the scientists knew that the only two sources for SOA production in this location were gasoline and diesel fumes, the study’s result pointed directly to gasoline as the key source.
“The contribution of diesel to SOA is almost negligible,” Bahreini said. “Even being conservative, we could deduce from our results that the maximum upper limit of contribution to SOA would be 20 percent.”
That leaves gasoline contributing the other 80 percent or more of the SOA, Bahreini said. The finding was published online March 1 in Geophysical Research Letters. “While diesel engines emit other pollutants such as soot and nitrogen oxides, for organic aerosol pollution they are not the primary culprit,” Bahreini said.
If the scientists were to apply their findings from the L.A. study to the rest of the world, a decrease in the emission of organic species from gasoline engines may significantly reduce SOA concentrations on a global scale as well. This suggests future research aimed at understanding ways to reduce gasoline emissions would be valuable.
The study was funded by NOAA’s Climate Change and Air Quality Programs, the California Air Resources Board and the National Science Foundation.
CIRES coauthors on the team include Joost de Gouw, Carsten Warneke, Harald Stark, William Dube, Jessica Gilman, Katherine Hall, John Holloway, Anne Perring, Joshua Schwarz, Ryan Spackman and Nicholas Wagner.
CU study: less hail may increase flooding on Front Range
Jan 9th
FROM COLORADO’S FRONT RANGE BY 2070
Summertime hail could all but disappear from the eastern flank of Colorado’s Rocky Mountains by 2070, says a new study by the National Oceanic and Atmospheric Administration, the University of Colorado Boulder’s Cooperative Institute for Research in Environmental Sciences and the National Center for Atmospheric Research.
Less hail damage could be good news for gardeners and farmers, said lead author Kelly Mahoney, a research scientist at CIRES, but a shift from hail to rain can also mean more runoff, which could raise the risk of flash floods. “In this region of elevated terrain, hail may lessen the risk of flooding because it takes awhile to melt,” Mahoney said. “Decision makers may not want to count on that in the future.”
For the new study, published this week in the journal Nature Climate Change, Mahoney and her colleagues used “downscaling” techniques to try to understand how climate change might affect hail-producing weather patterns across Colorado.
The research focused on storms involving pea-sized and smaller hailstones on Colorado’s Front Range, a region that stretches from the foothill communities of Colorado Springs, Denver and Fort Collins up to the Continental Divide. Colorado’s most damaging hailstorms tend to occur further east and involve larger hailstones not examined in this study.
In the summer in Colorado’s Front Range above about 7,500 feet, precipitation commonly falls as hail. Decision makers concerned about the safety of mountain dams and flood risk have been interested in how climate change may affect the amount and nature of precipitation in the region.
Mahoney and her colleagues began exploring that question with results from two climate models, which assumed that levels of climate-warming greenhouse gases will continue to increase in the future, from about 390 parts per million in the atmosphere today to about 620 parts per million in 2070.
But the weather processes that form hail, like thunderstorms, occur on much smaller scales than can be reproduced by global climate models. So the team “downscaled” the global model results twice: first to regional-scale models that can take regional topography and other details into account, then again to weather-scale models that can resolve individual storms and even the cloud processes that create hail. The regional-scale topography step was completed as part of NCAR’s North American Regional Climate Change Assessment Program.
Finally, the team compared the hailstorms of the future, from 2041 to 2070, to those of the past, from 1971 to 2000, as captured by the same sets of downscaled models. Results were similar in experiments with both climate models.
“We found a near elimination of hail at the surface,” Mahoney said.
In the future, increasingly intense storms may actually produce more hail inside clouds, the team found. However, because those relatively small hailstones fall through a warmer atmosphere, they melt quickly, falling as rain at the surface or evaporating back into the atmosphere. In some regions, simulated hail fell through an additional 1,500 feet of above-freezing air in the future as compared with the past.
The research team also found evidence that precipitation events over Colorado become more extreme in the future, while changes in hail may depend on the size of the hailstones — results that will be explored in more detail in ongoing work.
Mahoney’s postdoctoral research was supported by the Postdocs Applying Climate Expertise, or PACE, program administered by the University Corporation for Atmospheric Research and funded by CIRES Western Water Assessment, NOAA and the U.S. Bureau of Reclamation. PACE connects young climate scientists with real-world problems such as those faced by water resource managers.
Co-authors of the new paper include James Scott and Joseph Barsugli of CIRES and NOAA, Michael Alexander of the NOAA Earth System Research Laboratory and Gregory Thompson of NCAR.