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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any sign of recon yet?
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Quoting JamesSA:


Levi,

I snorkel off Cozumel whenever I get the chance, and the waters are anything but cold. They are beautiful and warm, even in the winter. Not much cold water to upwell in that part of the world.


I said north coast, not east lol.
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i'm not met, and don't really know what this could mean but in the last few frames of nhc wv loop it seems to me that the dry air that was headed south at a quick pace has leveled off and maybe even started going a bit west. am i seeing this right? can someone elaborate? if i am seeing this right then what effect if any will it have on 90l? tia
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Storm Relative 1km Geostationary Visible Imagery

Member Since: July 3, 2005 Posts: 420 Comments: 127543
Quoting Levi32:


They are semipermanently that way. The reason for that is because the trade winds in the Caribbean curve northwestward over the Yucatan, and when they blow offshore across the northern coastline, it upwells cold water along the shallow shelf.


Levi,

I snorkel off Cozumel whenever I get the chance, and the waters are anything but cold. They are beautiful and warm, even in the winter. Not much cold water to upwell in that part of the world.
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just encase anyone missed.
Link

enjoy!
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That shelf may have cooler waters, but still above what is needed to sustain a tropical cyclone.

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Is recon wheels up yet? nothing on GEarth
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Quoting Bretts9112:

and texas is not mexico
:)
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Gotta head to work. Later all.

Tropical Tidbit for Wednesday, July 27th, with Video
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Quoting lucreto:
Now the blob of convection appears to be moving southeast 90L looks like it will eventually slam into Hispanola and dissipate.


Comic relief?.. Don't quit your day job
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T.C.F.A.
XXL/INV90/XX
MARK
21.03N/86.93W


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Quoting angiest:


Oceanweather Inc (no idea if they are any good) is saying otherwise:



Low resolution means they won't be able to see such a thin region of cold water as the higher-resolution satellite products.
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Quoting hurricanehunter27:
For future refrence Hispanola is not Texas.

and texas is not mexico
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Caribbean Update July 27th 2011
img src="">
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Quoting lucreto:
Now the blob of convection appears to be moving southeast 90L looks like it will eventually slam into Hispanola and dissipate.


Teach me.
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Quoting lucreto:
Now the blob of convection appears to be moving southeast 90L looks like it will eventually slam into Hispanola and dissipate.


Its way past Hispaniola
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Quoting angelafritz:


I made a special effort to get it out by noon for you guys. ;)


Thank You
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Quoting floridaboy14:

Alright thanks and what do you think is the worst thing preventing invest 90L to stregnthen significantly? like wind shear, dry air, subsidence, and what do you think 90L will max out at?


All of the above....lumped into one word: Ridge. The big ridge over the central United States is causing all three of the negative factors that you just mentioned, and will likely keep 90L in check. As I stated in my blog, I see a max of a moderate tropical storm, somewhere around 50mph, perhaps slightly more if the system gets lucky. Things can change, so folks should keep their eyes peeled, but right now conditions do not look all that favorable to me. This system's theme is one of struggle.
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Thanks for the update Angela,great job filling in this week.
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52. 7544
im not even going to try 90l is one weird system and could do whatever it wants and has so predicting anything from this one will be just as wierd who knows it may take a 90 degree turn for all we know just baffeled on this one
Member Since: May 6, 2007 Posts: 0 Comments: 6690
Quoting lucreto:
Now the blob of convection appears to be moving southeast 90L looks like it will eventually slam into Hispanola and dissipate.
For future refrence Hispanola is not Texas.
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Thanks for the update Angela!
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It may not be the best looking TD/TS when it is declared, but there have been far worse.

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Quoting lucreto:
Now the blob of convection appears to be moving southeast 90L looks like it will eventually slam into Hispanola and dissipate.
Hispaniola?
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Quoting lucreto:
Now the blob of convection appears to be moving southeast 90L looks like it will eventually slam into Hispanola and dissipate.
Uhhh no.
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if it keeps moving west its moving out of those extreme high water temp
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Quoting Levi32:


They are semipermanently that way. The reason for that is because the trade winds in the Caribbean curve northwestward over the Yucatan, and when they blow offshore across the northern coastline, it upwells cold water along the shallow shelf.

Alright thanks and what do you think is the worst thing preventing invest 90L to stregnthen significantly? like wind shear, dry air, subsidence, and what do you think 90L will max out at?
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Quoting TropicalAnalystwx13:


OK, we need to get rid of this downcaster, wishcaster thing. Just because somebody is speaking their opinion, well that doesn't mean that they are downcasting or wishcasting.


+1000
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Quoting Levi32:
Thanks for the update Angela.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~``

The shelf water south of 22N along the coast of the northern Yucatan is very cold. 90L's center won't pass this close, but the convection associated with it, which should stay confined south of the center, may suffer as it passes over.



Oceanweather Inc (no idea if they are any good) is saying otherwise:

Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting angelafritz:


I made a special effort to get it out by noon for you guys. ;)


Thank you Angela! I appreciate it and I'm sure the other EDTers do too. ;)
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Quoting TxHurricanedude11:
i see we got downcasters now..crow is ready ;)


OK, we need to get rid of this downcaster, wishcaster thing. Just because somebody is speaking their opinion, well that doesn't mean that they are downcasting or wishcasting.
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I see the aircraft is up and flying!
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We'll probably see TD #4/Don at 5PM, after recon investigates. There isn't much doubt in my mind that 90L has a closed low-level circulation in that deep convection NE of the Yucatan Peninsula. Winds are between 35-40 mph, and the pressure is down to 1008 mb.

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Quoting floridaboy14:

Are the waters typically cold around the northern yucatan every year or is it just this year?


They are semipermanently that way. The reason for that is because the trade winds in the Caribbean curve northwestward over the Yucatan, and when they blow offshore across the northern coastline, it upwells cold water along the shallow shelf.
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Thanks Angela.
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31. angelafritz (Admin)
Quoting hurricaneben:
Great update, Angela. Yeah there is a chance the US might see it's first hurricane landfall since Ike almost 3 years ago.


I made a special effort to get it out by noon for you guys. ;)


I know that there are many other important ingrediants for tropical cyclone intensification, but it is scary how warm the waters are that 90L (likely soon to be Don) will be traversing.
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Quoting Levi32:
Dry air ahead in the central Gulf of Mexico:



It's being squeezed by the front to the north and 90L's moisture field.
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Nothing new from NWS Houston in this morning's discussion update.
Member Since: August 26, 2006 Posts: 16 Comments: 4766
90L not looking so hot right now. IMO the HH won't find a depression just yet, should still get there by tomorrow though.
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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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