Hurricanes and Climate Change: Huge Dangers, Huge Unknowns

By: Dr. Jeff Masters , 9:57 AM GMT on August 05, 2013

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Hurricane Sandy's enormous $65 billion price tag put that great storm in third place for the most expensive weather-related disaster in U.S. (and world) history, and six of the ten most expensive U.S. weather-related disasters since 1980 have been hurricanes. Thus, how the strongest hurricanes may be affected due a changing climate is a topic of critical concern. Since hurricanes are heat engines that extract heat energy from the oceans to power themselves, hurricane scientists are confident that the very strongest storms will get stronger by the end of the century, when Earth's land and ocean temperatures are expected to warm 2 - 3°C, to levels unmatched since the Eemian Era, 115,000 years ago. Computer modeling work consistently indicates that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift towards stronger storms, with intensity increases of 2–11% by 2100. But hurricanes are fussy creations, and are sensitive to wind shear and dry air. Although the strongest storms should get stronger when "perfect storm" conditions are present, these "perfect storm" conditions may become less frequent in the future, due to the presence of higher wind shear, altered atmospheric circulation patterns, or more dry air at mid levels of the atmosphere. Indeed, the climate models used to formulate the 2007 IPCC report suggested that we might see the strongest hurricanes getting stronger, but a decrease in the total number of hurricanes in the Atlantic (and worldwide) later this century. However, the latest set of models used to formulate the 2013 IPCC report left open the possibility that we might see in increase in the total number of hurricanes, and and increase in their intensity. Given the conflicting model results, we really don't know how global warming will affect the number of hurricanes and their intensity, but we run the risk of making one of humanity's greatest scourges worse.


Figure 1. The list of most expensive U.S. weather-related disasters since 1980 is dominated by hurricanes.

Climate models and hurricane frequency
The database we have on historical hurricanes does not extend far enough into the past and is not of high enough quality to make many judgements on how human-caused climate change may be affecting these great storms. A landmark 2010 review paper, "Tropical Cyclones and Climate Change", authored by ten top hurricane scientists concluded that the U.S. has not seen any long-term increase in landfalling tropical storms and hurricanes, and that "it remains uncertain whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes" (tropical cyclone is the generic term which encompasses tropical depressions, tropical storms, hurricanes, and typhoons.) Based in part on modeling studies using climate models run for the 2007 IPCC report, the scientists concluded that "it is likely that global mean tropical cyclone frequency will either decrease or remain unchanged owing to greenhouse warming." For example, one of the modeling studies the review paper quoted, Knutson et al. (2008), "Simulated reduction in Atlantic hurricane frequency under twenty-first-century warming conditions", projected a decrease in Atlantic tropical storms by 27% and hurricanes by 18% by the end of the century. An important reason that their model predicted these decreases was due to a predicted increase in wind shear. As I explain in my wind shear tutorial, a large change of wind speed with height over a hurricane creates a shearing force that tends to tear the storm apart. The amount of wind shear is critical in determining whether a hurricane can form or survive.

But a July 2013 study by MIT's Dr. Kerry Emanuel, "Downscaling CMIP5 climate models shows increased tropical cyclone activity over the 21st century", challenged this result. Dr. Emanuel argued that tropical cyclones are likely to become both stronger and more frequent as the climate continues to warm. This increase is most likely to occur in Western North Pacific, with smaller increases in the Atlantic. Dr. Emanuel took output from six newer higher-resolution climate models used to formulate the 2013 IPCC report, and used the output to drive a high-resolution hurricane model. The simulations found that the global frequency of tropical cyclones would increase by 11% to 40% by 2100, with intensity increases as well. The combined effects produced a global increase in Category 3 and stronger hurricanes of 40%. The behavior of these strongest hurricanes is critical, since they do most of the damage we observe. Over the past century, Category 3 - 5 hurricanes accounted for 85% of US hurricane damage, despite representing only 24% of U.S. landfalling storms. Category 4 and 5 hurricanes made up only 6% of all U.S. landfalls, but accounted for 48% of all U.S. damage (if normalized to account for increases in U.S. population and wealth, see Pielke et al., 2008.)


Figure 2. Projected changes in tropical cyclone track density during the 2006-2100 period compared to the 1950-2005 period, using output from six climate models included in the 2013 IPCC report. The global frequency of tropical cyclones is predicted to increase by 11% to 40%, with the largest changes occurring in the Northwest Pacific off the coast of Japan. Smaller increases are predicted for the Atlantic and near Australia. Image credit: Kerry Emanuel, "Downscaling CMIP5 climate models shows increased tropical cyclone activity over the 21st century", Proceedings of the National Academy of Sciences, July 8, 2013, doi: 10.1073/pnas.1301293110.

However, a study by Knutson et al. (2013), using the same latest-generation climate models as used by Emanuel (2013), but using the output from the models to drive a different high-resolution hurricane model, found a 20% decrease in Atlantic tropical storms and hurricanes by 2100. Two other 2013 studies by Villarini et al. and Camargo, also using output from the 2013 IPCC models, found essentially no change in Atlantic tropical cyclones. The reason for the differences, lies, in part, with how much global warming is assumed in the studies. Dr. Emanuel's study, which found an increase in tropical cyclone activity, assumed a worst-case warming situation (RCP 8.5), following the "business as usual" emissions path humanity is currently on. The Knutson et al. study, which found a decrease of 20% in Atlantic tropical cyclones, used a scenario (RCP 4.5) where it was assumed humans will wise up and cause about half of the worst-case greenhouse warming. The study found found "marginally significant" increases in Atlantic Category 4 and 5 hurricanes of 39% - 45% by 2100. These dramatically different results give credence to Dr. Emanuel statement at the end of his paper, "the response of tropical cyclones to projected climate change will remain uncertain for some time to come." The 2013 IPCC report also emphasized the high amount of uncertainty in how climate change might affect hurricanes, stating that there was "low confidence" that we have observed any increases in intense tropical cyclones due to human causes. However, since the 1970s, it is virtually certain (99 - 100% chance) that the frequency and intensity of hurricanes and tropical storms in the North Atlantic has increased, and there is medium confidence that a reduction in small air pollution particles (aerosols) over the North Atlantic caused part of this effect. The report's forecast for the future stated that it is "more likely than not" (50 - 100% chance) that human-caused climate change will cause a substantial increase in intense tropical cyclones in some ocean basins by 2100, with the Western North Pacific and Atlantic being at particular risk. Also, there will likely (66 - 100% chance) be an increase in both global mean tropical cyclone maximum wind speed and rain rates by 2100, and more likely than not (50 - 100% chance) that the increase in the most intense tropical cyclones will be larger than 10% in some basins.


Figure 3. Expected change in Atlantic Category 4 and 5 hurricanes per decade expected by the year 2100, according to Knutson et al. (2013), "Dynamical Downscaling Projections of 21st Century Atlantic Hurricane Activity: CMIP3 and CMIP5 Model-based Scenarios." This research used the latest generation of climate models from the 2013 IPCC report, and found "marginally significant" increases in Atlantic Category 4 and 5 hurricanes of 39% - 45% by 2100.

Commentary
Hurricane damages are currently doubling every ten years without the effect of climate change, according to Pielke et al., 2008. This is primarily due to the increasing population along the coast and increased wealth of the population. The authors theorize that the Great Miami Hurricane of 1926, a Category 4 monster that made a direct hit on Miami Beach, would have caused about $150 billion in damage had it hit in 2005. Thus, by 2015, the same hurricane would do $300 billion in damage, and $600 billion by 2025. This is without considering the impact that accelerating sea level rise will have on storm surge damages. Global sea level rise over the past decade has been about double what it was in the 20th century, and the rate of sea level rise is expected to increase further in the coming decades. Storm surge does the majority of damage in major hurricanes, and storm surges riding on top of higher sea levels are going to do a lot more damage in the coming decades. If we toss in the (controversial) increases in Category 3 and stronger storms like Dr. Emanuel suggests may occur, the hurricane damage math gets very impressive. We can also add onto that the relatively non-controversial increase in tropical cyclone rainfall of 20% expected by 2100, which will sharply increase damages due to fresh water river flooding. It is controversial whether or not we are already be seeing an increase in heavy precipitation events associated with tropical cyclones in the U.S., though. The total number of daily rainfall events exceeding 2" associated with tropical cyclones in the Southeast U.S. on a century time scale has not changed significantly, according to Groisman et al., 2004. But a 2010 study by Kunkel et al., "Recent increases in U.S. heavy precipitation associated with tropical cyclones", found that the number of Southeast U.S. tropical cyclone heavy precipitation events, defined as 1-in-5-year events, more than doubled between 1994 - 2008, compared to the long-term average from 1895 - 2008.


Figure 4. Time series of the 15-year running average (plotted at the end point of the 15-yr blocks) of a Tropical Cyclone Heavy Precipitation Index (red) and 15-year running average of U.S. landfalling hurricanes (blue). Note that there has been no long-term increase in U.S. landfalling hurricanes, but there has been a sharp increase in extreme rainfall events associated with landfalling tropical cyclones--the kind of rainfall events most likely to cause damaging flooding. Image credit: Kunkel et al. (2010), "Recent increases in U.S. heavy precipitation associated with tropical cyclones", Geophysical Research Letters.

It is essential that we limit coastal development in vulnerable coastal areas, particularly along barrier islands, to reduce some of the astronomical price tags hurricanes are going to be causing in the future. Adoption and enforcement of strict building standards is also a must, as well as more reforms to the government's National Flood Insurance Program (NFIP), which subsidizes development in high-risk coastal regions that private insurers won't touch. NFIP is now $25 - 30 billion in the red, thanks to Hurricane Katrina and Hurricane Sandy. Reform of NFIP is already underway. In 2012, before Sandy hit, Congress passed the Biggert-Waters Flood Insurance Reform Act, which requires people with NFIP policies to pay large premium increases of about 25% per year over the next five years. Naturally, this move has caused major controversy.

References
Camargo, S., (2013), "Global and regional aspects of tropical cyclone activity in the CMIP5 models," J. Climate.

Emanuel, K.A., 2013, "Downscaling CMIP5 climate models shows increased tropical cyclone activity over the 21st century", PNAS, July 8, 2013, doi: 10.1073/pnas.1301293110

Groisman, Pavel Ya, et al., "Contemporary changes of the hydrological cycle over the contiguous United States: Trends derived from in situ observations," Journal of Hydrometeorology 5.1 (2004): 64-85.

Knutson et al., 2010, "Tropical Cyclones and Climate Change", Nature Geoscience 3, 157 - 163, Published online: 21 February 2010 | doi:10.1038/ngeo779

Knutson et al., 2013, Dynamical Downscaling Projections of 21st Century Atlantic Hurricane Activity: CMIP3 and CMIP5 Model-based Scenarios, Journal of Climate 2013 ; e-View
doi: http://dx.doi.org/10.1175/JCLI-D-12-00539.1

Pielke, R.A, et al., 2008, "Normalized Hurricane Damage in the United States: 1900 - 2005," Natural Hazards Review, DOI:10.1061/ASCE1527-6988(2008)9:1(29)

Villarini, G, and G.A. Vecchi, 2012, "Twenty-first-century projections of North Atlantic tropical storms from CMIP5 models," Nature Clim. Change 2:604–607.

Related posts
Global warming and the frequency of intense Atlantic hurricanes: model results, my 2010 blog post.

Climate Central's analysis of the new 2013 Kerry Emanuel paper.

Goodbye, Miami: Jeff Goodell's sobering 2013 article in Rolling Stone on the challenges Miami faces due to sea level rise and hurricanes.


What the official climate assessments say about climate change and hurricanes
The 2013 IPCC report gives “low confidence”--a 20% chance--that we have observed a human-caused increase in intense hurricanes in some parts of the world. This is a reduction in odds from the 2007 report, which said that it was more likely than not (greater than 50% chance.) The IPCC likely took note of a landmark 2010 review paper, "Tropical Cyclones and Climate Change", authored by ten top hurricane scientists, which concluded that the U.S. had not seen any long-term increase in landfalling tropical storms and hurricanes, and that "it remains uncertain whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes." The 2013 IPCC report predicts that there is a greater than 50% chance (more likely than not) that we will see a human-caused increase in intense hurricanes by 2100 in some regions; this is also a reduction from the 2007 report, which said this would be likely (66% chance or higher.)

The May 2014 United States National Climate Assessment found that “The intensity, frequency, and duration of North Atlantic hurricanes, as well as the frequency of the strongest (Category 4 and 5) hurricanes, have all increased since the early 1980s. The relative contributions of human and natural causes to these increases are still uncertain. Hurricane-associated storm intensity and rainfall rates are projected to increase as the climate continues to warm.”

Jeff Masters

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Looks like on this run the FIM-8 is having trouble determining which storm to develop. Really comes down to where the upward motion of the MJO is the greatest imo.

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1867. Gearsts
Quoting 1861. MiamiHurricanes09:
Henriette developing a very compact eye.

West side of the system is very dry.
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Nothing too impressive. Just your average summer T storms for Florida.
But picked up over an inch of rain in a very short period of time, and it's still raining (South Fort Myers.
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nice tropical wave here!! NEEDS TO BE WATCH!
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Here we go!!
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Quoting 1835. Patrap:
City of Houston Cooling Center Locations

The City of Houston has opened the following locations as cooling centers. They include all City of Houston public libraries and Multi-Service Centers.

To arrange for transportation to/from City of Houston Cooling Centers, please call 311 (713-837-0311).


I just mowed the lawn, and it is HOT today in the Houston area. I just drank a whole 32 oz. Gatorade.
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Henriette developing a very compact eye.

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Link
That should work better!
NOT!! Just garbage.
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Quoting 1853. sar2401:

I'll take some scary. :-) I only get worried when I see rain rates of 8 or 9 inches per hour...and it lasts an hour. Then I start looking for the rowboat.


Yep, seen rates that high on my weather station. Luckily it usually only last for a few minutes raining at that rate.
So far we've picked up just over an 1" of rain in about 15 minutes.
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Cool Tokyo shower .gif!

It does look like the north pole took the week off from the big thaw, but it is back at it again and has another month before peak melt area.

http://arctic.atmos.uiuc.edu/cryosphere/arctic.se a.ice.interactive.html
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Are we still in the same steering regime as earlier in the season, or has the location of something changed?
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Quoting 1851. PalmBeachWeather:
That's unbelievable.


If it kept raining at that rate for a long time there would be a lot of local flooding.
But luckily the rain rate has now dropped to 2.27" per hour and hopefully the T- Storm will move out of the area soon.
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Quoting 1847. sar2401:

Possibly, but your link doesn't work. Try copy and pasting using the "link" option in the text box.


Thanks!
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Quoting 1850. sar2401:

Strange. Brings up a login screen when I try to view anything.


Try this one.

Link
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1853. sar2401
Quoting PalmBeachWeather:
Really.That's scary

I'll take some scary. :-) I only get worried when I see rain rates of 8 or 9 inches per hour...and it lasts an hour. Then I start looking for the rowboat.
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Quoting 1849. PalmBeachWeather:
Really.That's scary


Definitely scares the dog. He's hiding in the closet.
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Quoting 1848. Sfloridacat5:
rain rate now 5.06" of rain per hour. My Vantage Vue is saying "it raining cats and dogs."
That's unbelievable.
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1850. sar2401
Quoting Tropicsweatherpr:
The wave in Niger at 20E is now Pouch 20L

Strange. Brings up a login screen when I try to view anything.
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Quoting 1843. Sfloridacat5:
Heavy rain with thunder at my location in South Fort Myers Fl.
Current rain rate is 3.49" per hour.
Really.That's scary
Member Since: October 3, 2008 Posts: 0 Comments: 5940
rain rate now 5.06" of rain per hour. My Vantage Vue is saying "it raining cats and dogs."
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1847. sar2401
Quoting seer2012:
http://oiswww.eumetsat.org/IPPS/html/MSG/RGB/AIRM AS S/WESTERNAFRICA/IMAGESDisplay/NuOgcR6Lz2CA9

The next storm??

Possibly, but your link doesn't work. Try copy and pasting using the "link" option in the text box.
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Finnally,a decent hurricane in EPAC.


HURRICANE HENRIETTE DISCUSSION NUMBER 14
NWS NATIONAL HURRICANE CENTER MIAMI FL EP082013
200 PM PDT TUE AUG 06 2013

RECENT VISIBLE SATELLITE IMAGES SUGGEST THAT THE ORGANIZATION
OF THE SMALL HURRICANE HAS CONTINUED TO IMPROVE WITH A SMALL
EYE BECOMING EVIDENT. A SERIES OF MICROWAVE IMAGES DURING THE
PAST 12 HOURS OR SO HAVE CLEARLY SHOWN A CONTRACTING EYE.
THE INITIAL INTENSITY HAS BEEN INCREASED TO 80 KT...WHICH IS BETWEEN
THE SUBJECTIVE AND OBJECTIVE DVORAK ESTIMATES OF 77 KT
AND 85 KT...RESPECTIVELY. HENRIETTE IS EXPECTED TO REMAIN IN
AN ENVIRONMENT FAVORABLE FOR SOME ADDITIONAL INTENSIFICATION
DURING THE NEXT 12 TO 18 HOURS. AFTER THAT TIME...SLIGHTLY
COOLER SSTS AND A DRIER AND MORE STABLE AIR MASS SHOULD CAUSE A
GRADUAL WEAKENING TREND TO BEGIN. THE NHC INTENSITY FORECAST
IS A LITTLE ABOVE THE GUIDANCE DURING THE FIRST 12 TO 24 HOURS...
THEN LIES BETWEEN THE INTENSITY CONSENSUS AND THE SHIPS MODEL
THERAFTER.

HENRIETTE HAS BEEN MOVING ON A STEADY NORTHWESTWARD HEADING AT
ABOUT 9 KT TODAY. THE TRACK FORECAST REASONING REMAINS UNCHANGED
FROM THE PREVIOUS ADVISORY. HENRIETTE IS EXPECTED TO CONTINUE
NORTHWESTWARD FOR ANOTHER DAY OR SO...THEN TURN WESTWARD AS A
RIDGE RE-BUILDS TO THE NORTH OF THE CYCLONE. THE TRACK GUIDANCE IS
AGAIN IN FAIRLY GOOD AGREEMENT THROUGH 48 TO 72 HOURS...EXCEPT FOR
SOME FORWARD SPEED DIFFERENCES. THE NHC TRACK DURING THIS TIME
SPLITS THE DIFFERENCE BETWEEN THE SLOWER GFS AND THE FASTER ECMWF
AND LIES NEAR THE MODEL CONSENSUS. AS HENRIETTE WEAKENS AND
BECOMES A MORE SHALLOW CYCLONE LATER IN THE FORECAST PERIOD...IT IS
LIKELY TO TURN WEST-SOUTHWESTWARD IN THE LOW-LEVEL TRADEWIND FLOW.
THE TRACK GUIDANCE AT DAYS 4 AND 5 SHIFTED SOUTHWARD THIS CYCLE AND
THE OFFICIAL FORECAST HAS BEEN ADJUSTED IN THAT DIRECTION...BUT IT
REMAINS ALONG THE NORTHERN EDGE OF THE GUIDANCE ENVELOPE AT THOSE
TIMES.

FORECAST POSITIONS AND MAX WINDS

INIT 06/2100Z 14.7N 132.3W 80 KT 90 MPH
12H 07/0600Z 15.5N 133.6W 85 KT 100 MPH
24H 07/1800Z 16.4N 135.3W 80 KT 90 MPH
36H 08/0600Z 17.0N 137.1W 70 KT 80 MPH
48H 08/1800Z 17.3N 139.0W 60 KT 70 MPH
72H 09/1800Z 16.8N 143.0W 50 KT 60 MPH
96H 10/1800Z 16.0N 147.5W 35 KT 40 MPH
120H 11/1800Z 15.5N 152.5W 30 KT 35 MPH...POST-TROP/REMNT LOW

$$
FORECASTER BROWN
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anyone see the two spins yet!
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1844. sar2401
Quoting 69Viking:


Less than a month ago the Gulf was covered in convection with multiple ULL's from Texas to Florida. Now for the last couple of weeks the Gulf has cleared which has helped warm the waters. It's only a matter of time before something tries to spin up there.

Even with the multiple ULL's and blobs that bought so much rain to the SE, the majority of the Gulf was still free on convection. What was, and is, particularly noticeable is the lack of any activity off the Yucatan and in the BOC. When I was sailing, I avoided that area like the plague in summer, not just because of the risk of tropical storms, but because there was so much convection that it made things really unpleasant. Except for the heat this year, the strong trades would have made sailing from the BOC down to Belize and over to the Caymans and Jamaica a pleasure. This is the kind of sailing I did in the spring, and never would have dreamed trying in summer. It's hard to understand how unusual this situation is unless you sailed the Gulf and Caribbean for about 30 years, as I did.
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Heavy rain with thunder at my location in South Fort Myers Fl.
Current rain rate is 3.49" per hour.
Member Since: September 16, 2007 Posts: 0 Comments: 8338
Quoting 1836. biff4ugo:
The Bahamian air is moving south and Puerto Rico's is moving north... there is spin there somewhere!


Surface winds in the Bahamas are out of the SSE-S, upper level winds are out of the NNE-NE.
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http://oiswww.eumetsat.org/IPPS/html/MSG/RGB/AIRMAS S/WESTERNAFRICA/IMAGESDisplay/NuOgcR6Lz2CA9

The next storm??
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1840. Patrap
Orleans Parish

Heat Advisory
Statement as of 3:10 PM CDT on August 06, 2013

... Heat advisory now in effect until 8 PM CDT Wednesday...

* timing... during the late morning and afternoon hours on Wednesday.

* Duration... heat index values in excess of 105 degrees and as
high as 109 degrees are expected late Wednesday morning and afternoon
for several hours across the area.

Precautionary/preparedness actions...

A heat advisory means that a period of hot temperatures is
expected. The combination of hot temperatures and high humidity
will combine to create a situation in which heat illnesses are
possible. Drink plenty of fluids... stay in an air-conditioned
room... stay out of the sun... and check up on relatives and
neighbors.
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The wave in Niger at 20E is now Pouch 20L
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here the two spins I see on here!
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Is the FIM model new?
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The Bahamian air is moving south and Puerto Rico's is moving north... there is spin there somewhere!
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1835. Patrap
City of Houston Cooling Center Locations

The City of Houston has opened the following locations as cooling centers. They include all City of Houston public libraries and Multi-Service Centers.

To arrange for transportation to/from City of Houston Cooling Centers, please call 311 (713-837-0311).
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Quoting 1828. Patrap:


SEL4

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 474
NWS STORM PREDICTION CENTER NORMAN OK
225 PM CDT TUE AUG 6 2013

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF
CENTRAL MINNESOTA
SOUTHEASTERN NORTH DAKOTA
NORTHWESTERN WISCONSIN

* EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 225 PM UNTIL
900 PM CDT.

* PRIMARY THREATS INCLUDE...
A FEW TORNADOES POSSIBLE
SEVERAL LARGE HAIL EVENTS LIKELY WITH A FEW VERY LARGE HAIL
EVENTS TO 2 INCHES IN DIAMETER POSSIBLE
SEVERAL DAMAGING WIND GUSTS TO 70 MPH LIKELY

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTH NORTHWEST OF
ORTONVILLE MINNESOTA TO 60 MILES EAST NORTHEAST OF MINNEAPOLIS
MINNESOTA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

&&

DISCUSSION...AS A 50+ KT WESTERLY 500 MB JET STREAK CONTINUES TO
NOSE EASTWARD ACROSS THE NORTHERN PLAINS/UPPER MISSISSIPPI VALLEY
REGION LATE THIS AFTERNOON...DESTABILIZATION IS EXPECTED TO BECOME
SUFFICIENT FOR SUPERCELL DEVELOPMENT IN THE WARM SECTOR OF A WEAK
SURFACE WAVE. WITH SOME STRENGTHENING OF SOUTHERLY LOW-LEVEL FLOW
FIELDS...A REMNANT EFFECTIVE WARM FRONTAL ZONE ACROSS CENTRAL
MINNESOTA INTO THE MINNEAPOLIS AREA WILL PROVIDE A POTENTIAL FOCUS
FOR TORNADIC DEVELOPMENT THROUGH EARLY EVENING. OTHERWISE...THE
EVOLUTION OF AN ORGANIZED MESOSCALE CONVECTIVE SYSTEM MAY EVENTUALLY
OCCUR NEAR THE LOW AND ALONG A DEVELOPING COLD FRONT TRAILING TO THE
WEST...WHICH SHOULD PROPAGATE EAST SOUTHEASTWARD WITH THE RISK FOR
SEVERE WINDS AND HAIL ACROSS THE UPPER MISSISSIPPI VALLEY BY THIS
EVENING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
450. MEAN STORM MOTION VECTOR 29035.


...KERR


Been trying to find a chaser with live feed in the area, but can't find one as of yet.
Member Since: September 16, 2007 Posts: 0 Comments: 8338
1833. nigel20
I'm having a bit of lightning.
BBL
Member Since: November 6, 2010 Posts: 11 Comments: 8346
1832. nigel20
Quoting 1814. ackee:
I think if comes next week none of the reliable models still show no real development I think we will enD up with 12 name storm or less with most Developing close to home just my view

Hi ackee! There is plenty of time to get 14-16 named storms, especially because we already have 4 named storms.
Member Since: November 6, 2010 Posts: 11 Comments: 8346
Quoting 1379. Grothar:
There are often reports of sightings in Southern Virginia.



That would explain all the beady eyes and toothy grins in the Potomac then :)))
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1830. sar2401
Quoting RitaEvac:


It's in Celsius, so it's hotter than that

Understood, but 1 degree Celsius is 1.8 degrees Fahrenheit, so the difference is trivial. My point was that it really doesn't matter about the SST's if there are no other focusing mechanisms. The water could be 95, but, if there's a lack of vertical instability, nothing will happen. The whole "rocket fuel" theory means nothing until and unless there are other factors in place to cause storms. Just as a non-tropical example, we've had temperatures in the mid-90's and dewpoints in the high 70's, even the low 80's, over the last four days in SE Alabama. It's the kind of conditions that the flapping of the proverbial butterfly wings should have been enough to set off thunderstorms. Instead. we had mostly clear skies and no convection at all. Today, it's 95, but the dewpoint is actually lower, at 70, yet there are thunderstorms starting to form. We have a weak warm front coming in from the west that's providing just enough lift and instability to get storms started, even though conditions are not as "ideal" as they've been if you only look at temperature and dewpoint. We need some kind of focusing mechanism in the Gulf as well if we are to get storm formation. If that happens, warmer SST's then play a role. Until then, it just means people have a better time at the beach in nice warm water. :-)
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I see two spins together
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1828. Patrap


SEL4

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 474
NWS STORM PREDICTION CENTER NORMAN OK
225 PM CDT TUE AUG 6 2013

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF
CENTRAL MINNESOTA
SOUTHEASTERN NORTH DAKOTA
NORTHWESTERN WISCONSIN

* EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 225 PM UNTIL
900 PM CDT.

* PRIMARY THREATS INCLUDE...
A FEW TORNADOES POSSIBLE
SEVERAL LARGE HAIL EVENTS LIKELY WITH A FEW VERY LARGE HAIL
EVENTS TO 2 INCHES IN DIAMETER POSSIBLE
SEVERAL DAMAGING WIND GUSTS TO 70 MPH LIKELY

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 80 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 45 MILES NORTH NORTHWEST OF
ORTONVILLE MINNESOTA TO 60 MILES EAST NORTHEAST OF MINNEAPOLIS
MINNESOTA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.

&&

DISCUSSION...AS A 50+ KT WESTERLY 500 MB JET STREAK CONTINUES TO
NOSE EASTWARD ACROSS THE NORTHERN PLAINS/UPPER MISSISSIPPI VALLEY
REGION LATE THIS AFTERNOON...DESTABILIZATION IS EXPECTED TO BECOME
SUFFICIENT FOR SUPERCELL DEVELOPMENT IN THE WARM SECTOR OF A WEAK
SURFACE WAVE. WITH SOME STRENGTHENING OF SOUTHERLY LOW-LEVEL FLOW
FIELDS...A REMNANT EFFECTIVE WARM FRONTAL ZONE ACROSS CENTRAL
MINNESOTA INTO THE MINNEAPOLIS AREA WILL PROVIDE A POTENTIAL FOCUS
FOR TORNADIC DEVELOPMENT THROUGH EARLY EVENING. OTHERWISE...THE
EVOLUTION OF AN ORGANIZED MESOSCALE CONVECTIVE SYSTEM MAY EVENTUALLY
OCCUR NEAR THE LOW AND ALONG A DEVELOPING COLD FRONT TRAILING TO THE
WEST...WHICH SHOULD PROPAGATE EAST SOUTHEASTWARD WITH THE RISK FOR
SEVERE WINDS AND HAIL ACROSS THE UPPER MISSISSIPPI VALLEY BY THIS
EVENING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
450. MEAN STORM MOTION VECTOR 29035.


...KERR
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Look like we will maybe get Erin off Africa in 5 to 6 days!
GFS

CMC
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Quoting 1786. Sfloridacat5:


Don't forget it only takes 1 storm.
Hurricane Andrew (1st storm of the season) made landfall on Aug. 24th.
Just imagine everyone sitting around in early August 1992 with 0 storms so far in the season saying this year's a bust.


That sat picture is about 12 hours before Andrew's center pasted 25 miles to the north of my house. 72 hours before no one thought we would get anything and if we did it would probably just be a TS, goes to show you things can change pretty quickly in the tropics.
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1825. Patrap
Houston, we have a problem in NOLA

.."Big Duke NOLA 7's Central air just blew a Run Capacitor"..



Roger,copy,...recommend you go to Window AC, Main Bus B override..

As the A/C Man wont get there to Thursday Morn.

We have a backup EVA plan to replace the Run Cap...when you have time to copy,

Over ?



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1824. SLU
Quoting 1809. nigel20:
It seems as if the tropical wave will bring some wet weather the eastern Caribbean.


Its been baking hot in SLU since mid-July and as soon as the cricket arrives, here comes the rain. sigh.
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Soil moisture
Member Since: August 14, 2010 Posts: 10 Comments: 17491
1822. nigel20
Some very dark clouds as well as rain is to my south and west, but I'm not sure if I'll be getting any rain. I can hear a bit of thunder as well.



Member Since: November 6, 2010 Posts: 11 Comments: 8346
eumetsat picture of west Africa.

http://oiswww.eumetsat.org/IPPS/html/MSG/RGB/AIRM ASS/WESTERNAFRICA/index.htm
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1820. Thrawst
.
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1819. SLU
Quoting 1758. Tropicsweatherpr:


Agree with that. By the way NOAA will release their August forecast on Thursday.


My issue with NOAA is that they seem afraid to put their neck on the block and give a precise forecast. Instead, they are ultra conservative and tell you for example to expect 13 - 20 named storms, 6 - 11 hurricanes and 2 - 6 major hurricanes.
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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.