Drought continues; Yellowstone fires could become more frequent; 90L set to develop

By: Dr. Jeff Masters , 3:58 PM GMT on July 27, 2011

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Southern Drought Continues

Temperatures continue to soar into triple digits in the Southern Plains this week, and are expected to remain well above average for at least the next month. High air temperatures and low humidity (because of the low soil moisture) will continue to maintain drought conditions in the South unless we see some Gulf-landfalling tropical cyclones—a good remedy for a such an extreme drought.

This year's drought in the South is unprecedented by many definitions. Last year at this time, 0% of the contiguous U.S. was in exceptional drought. Last week, the exceptional drought region covered 11.96%. The area of contiguous U.S. in exceptional drought conditions has never been this high since the Drought Monitor record started in 2000. The highest it had been before June of this year was 7.85% in August of 2002.


Figure 1. Temperature anomaly (difference from average) in degrees Celsius for the period July 1 through July 25 (top) and soil moisture anomaly in millimeters (bottom) on July 25 (from the Climate Prediction Center).

In late June, the U.S. Department of Agriculture designated 213 counties in Texas (84% of the state) as primary natural disaster areas. As I mentioned yesterday, the Texas drought and wildfires are one of the nine billion-dollar disasters of 2011 so far. The National Climatic Data Center estimated that this event had cost up to $3 billion as of June 16. This number is surely rising every day that the South doesn't see rain.

New study concludes Yellowstone wildfires could become more frequent

In a study published this week by the Proceedings of the National Academy of Sciences, researchers have concluded that global warming could have a serious impact on the severity and frequency of wildfires in the Yellowstone region (an area where the states of Montana, Idaho, and Wyoming come together). Historically in this region, fewer than 5% of wildfire occurrences account for 95% of the total area burned. But in a global warming scenario, they found that fire activity could become more severe and more frequent, causing the ecosystem to change dramatically.

Using climate conditions and historical fire data from 1972 to 1999, it was possible to link certain environmental thresholds (temperature, humidity, etc) to past wildfire events. Then by employing the output of various climate models, fire frequency can be forecast well into the future. Figure 2 illustrates the result from one of the climate models they used in the study, and the upward trend of fire activity over the next 100 years. In 1988, a particularly hot and dry year, 36% of the park burned. The study uses this year as a baseline to compare future events.


Figure 2. Figure 2B from the manuscript. Observed burn area (blue line) median of predicted area burned (black dotted line), and ranges (light and dark orange) aggregated over the Yellowstone area defined by the study by Westerling et al. (Source).

What was once a low-probability event could become a high-probability event by mid-century. Fires that have only happened every 100 to 300 years in the past could now be occurring every 30 years in the future. The results of this research has implications for sub-alpine forests across the globe. Warming temperatures and decreasing humidity will lead to more wildfires, and will cost billions of dollars to fight them, if we choose to do so.

Invest 90L

90L has moved west overnight and looks ripe to develop today. While the upper level circulation (500 mb) is very much displaced, the lower level circulation looks strong and coherent through the system's mid-levels (850 and 700 mb). Thunderstorm activity continues to organize, and it appears that a surface circulation is developing. Moisture remains high in the system (around 4.5 g/kg specific humidity) and wind shear should be somewhat favorable as it crosses through the Gulf of Mexico. In terms of track, the statistical models have generally been favoring a Brownsville landfall scenario, but the dynamical models have been inching north over the past day or so. The HWRF is in line with the ECMWF deterministic today, with landfall near Corpus Christi.



The Hurricane Hunters have a mission scheduled for 18Z today (2pm EDT) to investigate whether or not 90L has a closed surface circulation. If it does, given the amount of organized convection and moderate wind speeds (around 34 mph in the latest invest update), the Hurricane Center will probably call this system at least Tropical Depression Four.

If 90L develops this afternoon, I will have another update to look at track and intensity forecasts.

Angela

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Quoting nrtiwlnvragn:


I generally don't post false info.
Just sometimes.
;-)
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Surface wind speed now at TS @ 19:11.30Z

SFMR Peak (10s) Sfc. Wind: 36 knots* (~ 41.4 mph*)
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Quoting nrtiwlnvragn:


I generally don't post false info.


Just caught me off guard, not doubting you.
Member Since: May 27, 2009 Posts: 0 Comments: 4436
1212. WxLogic
Quoting nrtiwlnvragn:


They will generally discount SFMR when it is greater than Flight Level.


Do they... interesting. Didn't quite paid attention to the detail there.
Member Since: August 14, 2008 Posts: 4 Comments: 4927
Quoting MrstormX:


Seriously?


I generally don't post false info.
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It's really a wait and see over the next 24 hours to see what happens with the intensity and the input from the HH folks to get the best handle on where the general location of landfall might be but if they do close off the circulation and initiate advisories this evening, we might see a rather large swatch of TS watches, from Texas to LA, until the models can narrow it down.
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Can't wait to see the cone of Doom, what the NHC is thinking with this in terms of strength/position will be fascinating.
Member Since: May 27, 2009 Posts: 0 Comments: 4436
Someone posted a link several weeks ago to how to read the flight data. Does anyone have that link? Can't figure out what's what yet.
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1198. WxLogic
Quoting nrtiwlnvragn:
AL, 04, 2011072718, , BEST, 0, 223N, 873W, 30, 1008, TD,


I guess they want to keep it at TD for now and TS by 8PM.
Member Since: August 14, 2008 Posts: 4 Comments: 4927
Time: 19:12:30Z
Coordinates: 21.65N 86.6167W
Acft. Static Air Press: 976.3 mb (~ 28.83 inHg)
Acft. Geopotential Hgt: 292 meters (~ 958 feet)
Extrap. Sfc. Press: 1009.8 mb (~ 29.82 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 207° at 29 knots (From the SSW at ~ 33.3 mph)
Air Temp: 21.5°C (~ 70.7°F)
Dew Pt: 12.8°C (~ 55.0°F)
Peak (10s) Flt. Lvl. Wind: 31 knots (~ 35.6 mph)
SFMR Peak (10s) Sfc. Wind: 34 knots (~ 39.1 mph)
SFMR Rain Rate: 9 mm/hr (~ 0.35 in/hSAY HI TO TROPICAL STORM DON
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Despite the renumber to a tropical depression, I wouldn't be surprised if it goes directly to Don with the recent tropical storm-force winds that are being found.
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Oh so we now have TD #4 it would seem, the fun begins.
Member Since: May 27, 2009 Posts: 0 Comments: 4436
Quoting WxLogic:
Definitely TS Don... 48MPH at the SFC

Time: 19:10:00Z
Coordinates: 21.7167N 86.7167W
Acft. Static Air Press: 973.4 mb (~ 28.74 inHg)
Acft. Geopotential Hgt: 320 meters (~ 1,050 feet)
Extrap. Sfc. Press: 1010.2 mb (~ 29.83 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 216° at 31 knots (From the SW at ~ 35.6 mph)
Air Temp: 19.0°C (~ 66.2°F)
Dew Pt: 13.1°C (~ 55.6°F)
Peak (10s) Flt. Lvl. Wind: 31 knots (~ 35.6 mph)
SFMR Peak (10s) Sfc. Wind: 42 knots (~ 48.3 mph)
SFMR Rain Rate: 23 mm/hr (~ 0.91 in/hr)
(*) Denotes suspect data


They will generally discount SFMR when it is greater than Flight Level.
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Quoting nrtiwlnvragn:
AL, 04, 2011072718, , BEST, 0, 223N, 873W, 30, 1008, TD,
And, there it is.
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1186. Patrap
NEXSAT GOM Loop
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1182. TX2FL
OMG..I'm gone for a season and come back to mayhem...

Wondering if this TS/Cat 1(?) will get far enough north to give some rain to the DFW area..I guess models will have a better grip after HH is done and logged?

Flying back into DFW this weekend, kind of don't want a wash out but I know the rain's needed.
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1181. angiest
Quoting WxLogic:
Definitely TS Don... 48MPH at the SFC

Time: 19:10:00Z
Coordinates: 21.7167N 86.7167W
Acft. Static Air Press: 973.4 mb (~ 28.74 inHg)
Acft. Geopotential Hgt: 320 meters (~ 1,050 feet)
Extrap. Sfc. Press: 1010.2 mb (~ 29.83 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 216° at 31 knots (From the SW at ~ 35.6 mph)
Air Temp: 19.0°C (~ 66.2°F)
Dew Pt: 13.1°C (~ 55.6°F)
Peak (10s) Flt. Lvl. Wind: 31 knots (~ 35.6 mph)
SFMR Peak (10s) Sfc. Wind: 42 knots (~ 48.3 mph)
SFMR Rain Rate: 23 mm/hr (~ 0.91 in/hr)
(*) Denotes suspect data


Well that changes things. Not flagged.
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Just post a blog entry to ignore user. I just did, my thoughts on 90L
Member Since: August 31, 2009 Posts: 0 Comments: 5628
Quoting nrtiwlnvragn:
invest_RENUMBER_al902011_al042011.ren 27-Jul-2011 19:17 3.8K


Seriously?
Member Since: May 27, 2009 Posts: 0 Comments: 4436

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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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