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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Our system approaching the Islands is actually more organized at the surface than is 90lL.....The MODELS are still winning over manys thinking!
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Quoting TampaSpin:
Still NO and i say NO Convergence with 90L! We are not gonna see a TD or Storm without Convergence. Still no Closed at the lower levels and still disorganized Yet in the Lower Levels at the Surface!



The only truthful thing about what you just said is that it has no convergence.
Member Since: July 6, 2010 Posts: 113 Comments: 32281
Still NO and i say NO Convergence with 90L! We are not gonna see a TD or Storm without Convergence. Still no Closed at the lower levels and still disorganized Yet in the Lower Levels at the Surface!

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Member Since: May 27, 2009 Posts: 0 Comments: 4438
It really isnt speed shear thats affecting this system right now it is Vertical Direction Shear which is the winds changing direction with height...the Low level flow is more to the Northwest and North and the Mid-Level flow is more westward around the high pressure...this thing is getting blown in two different directions and until it gets together and decideds which one will have more of an effect on it then it will not have a chance to get going...
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Quoting MississippiWx:
You can actually see that mid-level circulation being drawn into the rest of the system on the visible. Will be interesting to see what effect that has from now on...if any.


Yep, been watching that scoot over to the west. Gonna line up and stack itself before the day is over
Member Since: July 14, 2008 Posts: 1 Comments: 9630
Recon is up on Google Earth!!!!
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Given that we have live HH data coming in. I say NHC will hold it at no more than 90% and either classify it as a TD or TS by 8PM or before via a special statement.
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Quoting floridaboy14:
10 knots of the convection 20 over the center. its trying to hang on though
Its under convetion...
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Quoting floridaboy14:
10 knots of the convection 20 over the center. its trying to hang on though


10 knots over the center, 20 knots over the convection.

Member Since: July 6, 2010 Posts: 113 Comments: 32281
Quoting TropicalAnalystwx13:


The trade winds in the Caribbean blow water off the shelf, which induces upwelling.
actually.. that jives well with what i've been seeing regarding a typical counter-clockwise airflow in the BOC :)
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Quoting floridaboy14:

system DOES have an exposed center. its getting blasted by 20knots of NorthEasterly shear from the big ridge and 20knots isnt all that much but when you have a small system it can affect it. shear is weaking which is a good thing so this should not be more than a 50 60mph ts
I'm sorry but I don't see an exposed center. Yes you can see low-level cumulus being drawn in, but not the center itself.
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Keith,

He said he finally gave up drinking, then he ordered me a beer.
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Quoting TropicalAnalystwx13:


Shear is 10 knots, so it is isn't getting blasted. And the circulation IS NOT visible or exposed.


Indeed, if anything the NHC is going to upgrade this. Just because it isn't some pretty Hallmark satellite image doesn't mean it is being crushed by shear, there is a circulation and radar and recon will prove it.
Member Since: May 27, 2009 Posts: 0 Comments: 4438
Quoting TampaSpin:


Its did a bigger number with the models........there has been no Model at all for this system! STRANGE


Yes I know it is very Strange to say the lest....
and sorry about the spelling I was typing fast and just did not see my spelling since I'm not on here during work LOL

Taco :o)
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Quoting MississippiWx:
You can actually see that mid-level circulation being drawn into the rest of the system on the visible. Will be interesting to see what effect that has from now on...if any.


Now that the mid-level circulation is starting to couple with the low-level circulation, 90L should begin its strengthening phase, which should continue up to landfall.
Member Since: July 6, 2010 Posts: 113 Comments: 32281
Recon en route
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Quoting TropicalAnalystwx13:


Shear is 10 knots, so it is isn't getting blasted. And the circulation IS NOT visible or exposed.
10 knots of the convection 20 over the center. its trying to hang on though
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If anyone is looking for links to track 90L and the rest of the tropics this hurricane season check out this site. That way you don't have to bookmark hundreds of links :) You can find links to radars, surface obs, satellite imagery, etc.
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Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 27th day of the month at 17:28Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 300)
Mission Purpose: Investigate third suspect area (flight in the North Atlantic basin)
Mission Number: 1
Observation Number: 01

Mandatory Data...

Observation Time: Wednesday, 17:25Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 27.9N 89.6W
Location: 146 miles (235 km) between the SSE and S (169°) from New Orleans, LA, USA.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 7,310 meters
Flight Level Wind: 5 knots (~ 5.8 mph) (Bearing was unavailable.)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: -15°C
Flight Level Dew Point: Not available, probably because the dew point hygrometer was not working.
Weather (within 30 nautical miles): Broken clouds (5/8 to 7/8 cloud coverage)
400 mb Surface Altitude: 7,610 geopotential meters
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You can actually see that mid-level circulation being drawn into the rest of the system on the visible. Will be interesting to see what effect that has from now on...if any.
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Quoting kwgirl:
I'm not Levi but I would hazard a guess that there is deep water there, and/or maybe an underground river spewing into the gulf. Either one should be the only reasons.
would you rule out frictional forces from the gulf stream?
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Quoting floridaboy14:

system DOES have an exposed center. its getting blasted by 20knots of NorthEasterly shear from the big ridge and 20knots isnt all that much but when you have a small system it can affect it. shear is weaking which is a good thing so this should not be more than a 50 60mph ts


Shear is 10 knots, so it is isn't getting blasted. And the circulation IS NOT visible or exposed.
Member Since: July 6, 2010 Posts: 113 Comments: 32281
Recon starting

000
URNT11 KNHC 271728
97779 17250 40279 89600 73100 99005 65//2 /5761
RMK AF300 01DDA INVEST OB 01
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Quoting angiest:


We need the rain everywhere in Texas, but as severe as the drought is, getting it all at once (we are 20"+ down here) would be a disaster as well. Two to four inches would be nice.


That seems reasonable. It would be nice if you could get about 5 very weak tropical storms that quickly move in over a 3 month period! That would be too good to be true though. It is getting dry up here in Arkansas as well, and the heat is relentless. I am ready for a pattern change.
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Quoting kwgirl:
I'm not Levi but I would hazard a guess that there is deep water there, and/or maybe an underground river spewing into the gulf. Either one should be the only reasons.


The trade winds in the Caribbean blow water off the shelf, which induces upwelling.
Member Since: July 6, 2010 Posts: 113 Comments: 32281
Corpus Christie Bay...

(an excellant Robert Earl Keen song)
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Quoting SouthDadeFish:
I don't understand that talks of poor satellite appearance. Convection continues to fire and expand over the center. Yes there is northerly shear acting on the system, but the center isn't exposed. I mean this is only a developing TD not a hurricane :P

system DOES have an exposed center. its getting blasted by 20knots of NorthEasterly shear from the big ridge and 20knots isnt all that much but when you have a small system it can affect it. shear is weaking which is a good thing so this should not be more than a 50 60mph ts
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Quoting SouthDadeFish:
I don't understand that talks of poor satellite appearance. Convection continues to fire and expand over the center. Yes there is northerly shear acting on the system, but the center isn't exposed. I mean this is only a developing TD not a hurricane :P


Plus radar:

Member Since: May 27, 2009 Posts: 0 Comments: 4438
Quoting taco2me61:


Yes I have to agree.... I do know this storm has done a number onn everyone in here thats for sure....

I sure hope HH get in there so that way we all will know what to think about futer "Don"....

Taco :o)


Its did a bigger number with the models........there has been no Model at all for this system! STRANGE
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Quoting hydrus:
I agree...However, I truly believe it will never be a hurricane, and it still could miss Texas. I was hoping they would at least get some rain..
North Texas here, and boy do we need the rain. I wanna "wishcast" 90L so bad, since a couple of the ensemble models have it coming right to my backyard, but I will wait, watch, and see what happens.
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286. JRRP
wepaa


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Quoting MississippiWx:


And up go the gas prices...


No, they said it wouldn't affect production....okkkk, then I guess production just goes on without anybody at the controls
Member Since: July 14, 2008 Posts: 1 Comments: 9630
Quoting Leafgreen:

Levi, why is the water on this shelf so cold?
I'm not Levi but I would hazard a guess that there is deep water there, and/or maybe an underground river spewing into the gulf. Either one should be the only reasons.
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Quoting SouthDadeFish:
I don't understand that talks of poor satellite appearance. Convection continues to fire and expand over the center. Yes there is northerly shear acting on the system, but the center isn't exposed. I mean this is only a developing TD not a hurricane :P


+1.
Member Since: July 6, 2010 Posts: 113 Comments: 32281
Vote 2am update for 90L
A:lower than 80%
B: 80%
c: 90%
D: 100%
E: TD/TS
im going with B
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Quoting sky1989:


I do think that some of Texas will get rain from this, but I do not see it as a drought buster either.


We need the rain everywhere in Texas, but as severe as the drought is, getting it all at once (we are 20"+ down here) would be a disaster as well. Two to four inches would be nice.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
I don't understand that talks of poor satellite appearance. Convection continues to fire and expand over the center. Yes there is northerly shear acting on the system, but the center isn't exposed. I mean this is only a developing TD not a hurricane :P
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Quoting RitaEvac:
Announced on local news that Shell has begun evacuating their workers offshore


And up go the gas prices...
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Nice wide spread covering Texas!
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Quoting RitaEvac:
Announced on local news that Shell has begun evacuating their workers offshore


bet they are watching the fish and birds then snicker snicker
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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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