Volcanic Winter

By: Dr. Jeff Masters , 1:18 PM GMT on April 24, 2009

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"The sun was dark and its darkness lasted for eighteen months; each day it shone for about four hours; and still this light was only a feeble shadow; the fruits did not ripen and the wine tasted like sour grapes." As this Michael the Syrian quote regarding the weather of 536 A.D. demonstrates, a climate catastrophe that blots out the sun can really spoil your day. Procopius of Caesarea remarked: "During this year [536 A.D.] a most dread portent took place. For the sun gave forth its light without brightness. and it seemed exceedingly like the sun in eclipse, for the beams it shed were not clear." Many documents from 535 - 536 A.D.--the time of King Arthur in Britain--speak of the terrible "dry fog" or cloud of dust that obscured the sun, causing widespread crop failures in Europe, and summer frosts, drought, and famine in China. Tree ring studies in Europe confirm several years of very poor growth around that time, and ice cores from Greenland and Antarctica show highly elevated levels of atmospheric sulfuric acid dust existed.

Though some scientists believe the climate calamity of 535-536 A.D. was due to a comet or asteroid hitting the Earth, it is widely thought that the event was probably caused by the most massive volcanic eruption of the past 1500 years. This eruption threw so much sulfur dioxide (SO2) gas into the stratosphere that a "Volcanic Winter" resulted. Sulfur dioxide reacts with water to form sulfuric acid droplets (aerosol particles), which are highly reflective and reduce the amount of incoming sunlight. The potential eruption that led to the 535 - 536 A.D. climate calamity would have likely been a magnitude 7 event on the Volcanic Explosivity Index (VEI)--a "super colossal" eruption that one can expect to occur only once every 1000 years. The Volcanic Explosivity Index is a logarithmic scale like the Richter scale used to rate earthquakes, so a magnitude 7 eruption would eject ten times more material than the two largest eruptions of the past century--the magnitude 6 eruptions of Mt. Pinatubo in the Philippines (1991) and Novarupta in Alaska (1912).


Figure 1. An 18 km-high volcanic plume from one of a series of explosive eruptions of Mount Pinatubo beginning on 12 June 1991, viewed from Clark Air Base (about 20 km east of the volcano). Three days later, the most powerful eruption produced a plume that rose nearly 40 km, penetrating well into the stratosphere. Pinatubo's sulfur emissions cooled the Earth by about 1°F (0.5°C) for 1 - 2 years. (Photograph by David H. Harlow, USGS.)

Super-colossal eruptions
There has been only one other magnitude 7 "super-colossal" eruption in the past 1500 years--the massive eruption of the Indonesian volcano Tambora in 1815. The sulfur pumped by this eruption into the stratosphere dimmed sunlight so extensively that global temperatures fell by about 2°F (1°C) for 1 - 2 years afterward. This triggered the famed Year Without a Summer in 1816. Killing frosts and snow storms in May and June 1816 in Eastern Canada and New England caused widespread crop failures, and lake and river ice were observed as far south as Pennsylvania in July and August. The Tambora eruption was about 40% smaller than the 535 - 536 A.D. event, as measured by the number of sulfur aerosol particles deposited in Greenland ice cores.

In an article published in 2008 in the American Geophysical Union journal EOS, Dr. Ken Verosub of the University of California, Davis Department of Geology estimated that future eruptions capable of causing "Volcanic Winter" effects severe enough to depress global temperatures by 2°F (1°C) and trigger widespread crop failures for 1 - 2 years afterwards should occur about once every 200 - 300 years. Even a magnitude 6 eruption, such as the 1600 eruption of the Peruvian volcano Huaynaputina, can cause climatic change capable of killing millions of people. The Huaynaputina eruption is blamed for the Russian famine of 1601-1603, which killed over half a million people and led to the overthrow of Tsar Boris Godunov. Thankfully, the climatic impacts of all of these historic magnitude 6 and 7 eruptions have been relatively short-lived. After about two years, the sulfuric acid aerosol particles have settled out of the stratosphere, returning the climate to its former state.

Mega-colossal eruptions
Even more extreme eruptions have occurred in Earth's past--eruptions ten times more powerful than the Tambora eruption, earning a ranking of 8 out of 8 on the Volcanic Explosivity Index (VEI). These "mega-colossal" eruptions occur only about once every 10,000 years, but have much longer-lasting climatic effects and thus are a more significant threat to human civilization. According to the Toba Catastrophe Theory, a mega-colossal eruption at Toba Caldera, Sumatra, about 74,000 years ago, was 3500 times greater than the Tambora eruption. According to model simulations, an eruption this large can pump so much sulfur dioxide gas into the stratosphere that the atmosphere does not have the capacity to oxidize all the SO2 to sulfuric acid aerosol. The atmosphere oxidizes as much SO2 as it can, leaving a huge reservoir of SO2 in the stratosphere. This SO2 gradually reacts to form sulfuric acid as the OH radicals needed for this reaction are gradually produced. The result is a much longer-lasting climate effect than the 1 - 2 years that the magnitude 6 and 7 events of 535, 1600, 1815, and 1991 lasted. A magnitude 8 eruption like the Toba event can cool the globe for 6 - 10 years (Figure 3), which may be long enough to trigger an ice age--if the climate is already on the verge of tipping into an ice age. Rampino and Self (1992) argued that the sulfur aerosol veil from Toba was thick and long-lasting enough to cool the globe by 3 - 5°C (5 - 9°F), pushing the climate--which was already cooling and perhaps headed towards an ice age--into a full-scale ice age. They suggested that the response of Canada to the volcano played a particularly important role, with their model predicting a 12°C (22°F) reduction in summer temperatures in Canada. This would have favored the growth of the Laurentide ice sheet, increasing the reflectivity (albedo) of the Earth, reflecting more sunlight and reducing temperatures further. The controversial Toba Catastrophe Theory asserts that the resulting sudden climate change reduced the Earth's population of humans to 1,000 - 10,000 breeding pairs. More recent research has shed considerable doubt on the idea that the Toba eruption pushed the climate into an ice age, though. Oppenheimer (2002) found evidence supporting only a 2°F (1.1°C) cooling of the globe, for the 1000 years after the Toba eruption. Zielinski et al. (1996) argued that the Toba eruption did not trigger a major ice age--the eruption merely pushed the globe into a cool period that lasted 200 years. Interestingly, a previous super-eruption of Toba, 788,000 years ago, coincided with a transition from an ice age to a warm period.


Figure 2. The 100x30 square kilometer Toba Caldera is situated in north-central Sumatra around 200 km north of the Equator. It is comprised of four overlapping calderas aligned with the Sumatran volcanic chain. Repeated volcanic cataclysms culminated in the stupendous expulsion of the Younger Toba Tuff around 74,000 years ago. The lake area is 100 square kilometers. Samosir Island formed as a result of subsequent uplift above the evacuated magma reservoir. Such resurgent domes are typically seen as the concluding phase of a large eruption. Landsat Enhanced Thematic Mapper Plus (ETM+) browse images for path/row 128/58 (6 September 1999) and 129/58 (21 January 2001) from http://landsat7.usgs.gov/. Copyright USGS. Image source: Oppenheimer, C., 2002, "Limited global change due to the largest known Quaternary eruption, Toba 74 kyr BP?"Quaternary Science Reviews, 21, Issues 14-15, August 2002, Pages 1593-1609.


Figure 3. Total mass of sulfur dioxide and sulfate aerosol in the stratosphere (heavy solid and dotted lines, respectively) modeled for a 6 petagram stratospheric injection of SO2. Observed SO2 and aerosol mass for the 1991 Pinatubo eruption are shown for comparison. The much larger amount of SO2 in the Toba simulation soaks up all available oxidants in the stratosphere leading to a much longer lifetime of SO2 and, in turn, prolonging the manufacture of sulfate aerosol. Data from Read et al. (1993) and Bekki et al. (1996). Image source: Oppenheimer, C., 2002, "Limited global change due to the largest known Quaternary eruption, Toba 74 kyr BP?"Quaternary Science Reviews, 21, Issues 14-15, August 2002, Pages 1593-1609.

When can we expect the next mega-colossal eruption?
Given the observed frequency of one mega-colossal magnitude 8 volcanic eruption every 1.4 million years, the odds of another hitting in the next 100 years is about .014%, according to Mason et al., 2004. This works out to a 1% chance over the next 7200 years. Rampino (2002) puts the average frequency of such eruptions at once every 50,000 years--about double the frequency with which 1-km diameter comets or asteroids capable of causing a similar climatic effect hit the Earth. A likely location for the next mega-colossal eruption would be at the Yellowstone Caldera in Wyoming, which has had magnitude 7 or 8 eruptions as often as every 650,000 years. The last mega-colossal eruption there was about 640,000 years ago. But don't worry, the seismic activity under Yellowstone Lake earlier this year has died down, and the uplift of the ground over the Yellowstone caldera that was as large as 7 cm/yr (2.7 inches/yr) between 2004 - 2006 has now fallen to 4 cm/yr, according to the Yellowstone Volcano Observatory. The USGS states that "the Yellowstone volcanic system shows no signs that it is headed toward such an eruption. The probability of a large caldera-forming eruption within the next few thousand years is exceedingly low".

What would happen if a magnitude 8 mega-colossal eruption were to occur today?
If a mega-colossal eruption were to occur today, it would probably not be able to push Earth into an ice age, according to a modeling study done by Jones et al. (2005). They found that an eruption like Toba would cool the Earth by about 17°F (9.4°C) after the first year (Figure 3), and the temperature would gradually recover to 3°F (1.8°C) below normal ten years after the eruption. They found that the eruption would reduce rainfall by 50% globally for the first two years, and up to 90% over the Amazon, Southeast Asia, and central Africa. This would obviously be very bad for human civilization, with the cold and lack of sunshine causing widespread crop failures and starvation of millions of people. Furthermore, the eruption would lead to a partial loss of Earth's protective ozone layer, allowing highly damaging levels of ultraviolet light to penetrate to the surface.

Not even a mega-colossal eruption of this magnitude would stop global warming, though. The level of greenhouse gases in the atmosphere would not be affected by the volcanic eruption, and warming would resume where it left off once the stratospheric dust settled out in a decade. With civilization crippled by the disaster, greenhouse gas emissions would be substantially reduced, though (small solace!) If we really want to say goodbye to civilization, a repeat of the only magnitude 9 eruption in recorded history should do the trick--the magnitude 9.2 La Garita, Colorado blast of 27.8 million years ago (Mason et al., 2004).


Figure 4. Annual near-surface temperature anomalies for the year following a mega-colossal volcanic eruption like the Toba eruption of 74,000 years ago, if it were to occur today. Most land areas cool by 22°F (12°C) compared to average. Some areas, like Africa, cool by 29°F (16°C). Image credit: Jones, G.S., et al., 2005, "An AOGCM simulation of the climate response to a volcanic super-eruption", Climate Dynamics, 25, Numbers 7-8, pp 725-738, December, 2005.

What would happen if a magnitude 7 super-colossal eruption were to occur today?
An eruption today like the magnitude 7 events of 535 A.D. or 1815 would cause cause wide-spread crop failures for 1 - 2 years after the eruption. With food supplies in the world already stretched thin by rising population, decreased water availability, and conversion of cropland to grow biofuels, a major volcanic eruption would probably create widespread famine, threatening the lives of millions of people. Wars over scarce resources might result. However, society's vulnerability to major volcanic eruptions is less than it was, since the globe has warmed significantly in the past 200 years. The famines from the eruptions of 1600 and 1815 both occurred during the Little Ice Age, when global temperatures were about 1.4°F (0.8°C) cooler than today. Crop failures would not be as wide-spread with today's global temperatures, if a suer-colossal eruption were to occur. Fifty years from now, when global temperatures are expected to be at least 1°C warmer, a magnitude 7 eruption should only be able to cool the climate down to year 2009 levels.

Volcanoes also warm the climate
While volcanoes cool the climate on time scales of 1 - 2 years, they act to warm the climate over longer time scales, since they are an important source of natural CO2 to the atmosphere. Volcanoes add 0.1 - 0.3 gigatons (Gt) of carbon to the atmosphere each year, which is about 1 - 3% of what human carbon emissions to the atmosphere were in 2007, according to the Global Carbon Project. In fact, volcanoes are largely responsible for the natural CO2 in the atmosphere, and helped make life possible on Earth. Why, then, haven't CO2 levels continuously risen over geologic time, turning Earth into a steamy hothouse? In fact, CO2 levels have fallen considerably since the time of the dinosaurs--how can this be? Well, volcano-emitted CO2 is removed from the atmosphere by chemical weathering. This occurs when rain and snow fall on rocks containing silicates. The moisture and silicates react with CO2, pulling it out of the air. The carbon removed from the air is then washed into the sea, where it ends up in ocean sediments that gradually harden into rock. Rates of chemical weathering on Earth have accelerated since the time of the dinosaurs, largely due to the recent uplift of the Himalaya Mountains and Tibetan Plateau. These highlands undergo a tremendous amount of weathering, thanks to their lofty heights and the rains of the Asian Monsoon that they capture. Unfortunately, chemical weathering cannot help us with our current high levels of greenhouse gases, since chemical weathering takes thousands of years to remove significant amounts of CO2 from the atmosphere. It takes about 100,000 years for silicate weathering to remove 63% of the CO2 in the atmosphere. Thus, climate models predict that chemical weathering will solve our greenhouse gas problem in about 100,000 - 200,000 years.

For further information
PBS TV special on the 535-536 A.D. disaster.
Newspaper articles on the 535-536 A.D. disaster.
Volcanic winter article from wikipedia.
Realclimate.org has a nice article that goes into the volcano-climate connection in greater detail.

References
Bekki, S., J.A. Pyle, W. Zhong, R. Toumi, J.D. Haigh and D.M. Pyle, 1996, "The role of microphysical and chemical processes in prolonging the climate forcing of the Toba eruption", Geophysical Research Letters 23 (1996), pp. 2669-2672.

Jones, G.S., et al., 2005, "An AOGCM simulation of the climate response to a volcanic super-eruption", Climate Dynamics, 25, Numbers 7-8, pp 725-738, December, 2005.

Rampino, M.R., and S. Self, 1993, "Climate-volcanism feedback and the Toba eruption of 74,000 years ago", Quaternary Research 40 (1993), pp. 269-280.

Mason, B.G., D.M. Pyle, and C. Oppenheimer, 2004, "The size and frequency of the largest observed explosive eruptions on Earth", Bulletin of Volcanology" 66, Number 8, December 2004, pp 735-748.

Oppenheimer, C., 2002, "Limited global change due to the largest known Quaternary eruption, Toba 74 kyr BP?"Quaternary Science Reviews, 21, Issues 14-15, August 2002, Pages 1593-1609.

Rampino, M.R., 2002, "Supereruptions as a Threat to Civilizations on Earth-like Planets", Icarus, 156, Issue 2, April 2002, Pages 562-569.

Read, W.G., L. Froidevaux and J.W. Waters, 1993, "Microwave Limb Sounder measurements of stratospheric SO2 from the Mt. Pinatubo eruption", Geophysical Research Letters 20 (1993), pp. 1299-1302.

Verosub, K.L., and J. Lippman, 2008, "Global Impacts of the 1600 Eruption of Peru's Huaynaputina Volcano", EOS 89, 15, 8 April 2008, pp 141-142.

Zielinski, G.A. et al., 1996, "Potential Atmospheric Impact of the Toba Mega-Eruption 71,000 Years Ago", Geophysical Research Letters, 23, 8, pp. 837-840, 1996.

Portlight moves to provide relief for South Carolina wildfires
South Carolina's biggest wildfire in more than three decades --a blaze four miles wide--destroyed dozens of homes near Myrtle Beach yesterday. Portlight Strategies, Inc. is preparing to respond to this disaster, focusing on providing drinks and sanitary products to firefighters, particularly to rural volunteer fire departments and other first responders which do not have the same resources as some of the larger paid departments. To help out, visit the Portlight South Carolina fire relief web page. Thanks!

Jeff Masters

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Quoting PresidentialElection:
I had to give Christian his hot bottle of milk, it was due already.


I didn't need to know that.
I thought this was a Weather Blog...
Member Since: Posts: Comments:
vortex:yes it has combined w/bird and another strain and is passed person to person,the biggest thing w/this strain is its attacking perfectly healthy,strong middle aged people,NOT the infants and elderly,luckily it does not appear to be deadly if treated w/tamiflu.....
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Quoting Vortex95:
Wondering about Swine flu can it go from person to person?


Seems so - DHS is on it (Yikes! build a fence)

U.S. Homeland Security Secretary Janet Napolitano are scheduled to hold a briefing on Sunday at 12:30 p.m. Eastern time to provide an update on the outbreak of swine flu
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Quoting PresidentialElection:


If it insulted you, then I apologies.

Insulted no. But you really dont need to post that here.
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Quoting PresidentialElection:
I had to give Christian his hot bottle of milk, it was due already.

Im not trying to sound rude but do you really have to share that in a weather blog?
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zoo..same thing happened to me a few weeks ago - lost everything on my computer due to a hard-drive crash. I feel your pain!

Melissa
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good sunday morning storm!!!,Do you think we'll be getting the TC season started earlier than average this season????,I remember specifically that you were a bit concerned for more continental landfalls do to the position and strength of the A/B high last year,before gustov and Ike hit,same setting up this year???
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off to do Sunday chores, thanks for the info
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Orca - like that one - easy to access.

Storm - doing well, haven't been on much, too busy at work, etc. Trying to get my computer set back up. Can hardly believe the season is about to be here again.
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Orca:,funniest thing I've heard all week(CJ joke)....I have a question,Its about 88 degrees and hotter than heck right now down here in sarasota....could you send us down one more shot of maritime air?????,please????...we'd all really appreciate it!!!!,lol.....
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Quoting zoomiami:
456 - Thanks! NCEP was the one I was remembering. (great word hmm)


no prob
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Same JFV, Different Season...
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Quoting zoomiami:
456 - Thanks! NCEP was the one I was remembering. (great word hmm)


Here is another one I like to use.. nothing fancy, but easy access to the model runs.
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PSU and LSU weather walls are 2 of my personal favorite's,so much free info!!!!!!!!!!
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Hi Storm -- how are you? good to see you back for the season.
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Quoting PresidentialElection:


My pal, I had to mainly take general ed courses to accquire that degree. On the other hand, with my B.A. persues, I'm now finally taking courses directly affeliated with meteorology, have you've caught the drift of my explination as of yet, my friend from the north?



absolutely,my sir!!!!!!!
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Quoting PresidentialElection:


My pal, I had to mainly take general ed courses to accquire that degree. On the other hand, with my B.A. persues, I'm now finally taking courses directly affeliated with meteorology, have you've caught the drift of my explination as of yet, my friend from the north?
Quoting PresidentialElection:


My pal, I had to mainly take general ed courses to accquire that degree. On the other hand, with my B.A. persues, I'm now finally taking courses directly affeliated with meteorology, have you've caught the drift of my explination as of yet, my friend from the north?
my friend, after what you said I am having a hard believeing you. Ok buddy?
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456 - Thanks! NCEP was the one I was remembering. (great word hmm)
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Thanks orca, stillwaiting - I have stormjunkie, and now H23, that should pretty much work. Now just have to go through all of them to organize for my links.

What a pain. I'm going to find one of those utilities that allow you to organize and backup your favorites.


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Quoting zoomiami:
Ok, so I have a question, and you all need to be nice. All of the links on my computer (gathered for two years) were lost when the computer got replaced. One of the sites had all the different weather maps, you could choose surface conditions, precipitation, etc. I have been looking for the last little while, and can't seem to find it.

More specifically, looking for the map that shows the pressure gradient, to see what all these winds are about.

Thanks!


Was it:

NCEP
WU Models
Plymouth State Models
Navy Model Graphics
FNOMC Models

Or the University of Wyoming
Member Since: July 24, 2005 Posts: 407 Comments: 19076
In regards once again to the GFS output keep in mind may systems are quite rare,also this is around the time the GFS begins to spit out its ghost storms.

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Quoting zoomiami:
Adrian - your site is great, and will certainly help me rebuild my links.


Deb, someone posted this one yesterday... sorry cannot remember who it was to give them the credit... but it has lots of good information on it.
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zoo:stormjunkie.com,has alot of great links for college weather walls,ect.....
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Quoting stillwaiting:
PE: how did you get a AA degree in meteorology,if you don't know that 994mb would not usually be a Cane???,just curious,not trying to be malicious,my friend to the south!!!....


Cracker Jacks?
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850. beell
A very strong and real threat for dangerous tornados today near the triple point which should be close to the eastern OK panhandle. S along the dryline, and to the NE across KS along the slowly drifting warm front boundary.

A perfect chase day shaping up.



DAY 1 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0837 AM CDT SUN APR 26 2009

VALID 261300Z - 271200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF TX...OK...AND
KS...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
FROM S CNTRL TX INTO THE LWR MO/MID MS VLYS...

CORRECTED DEWPOINTS IN NY/PA/MA/CT

...SYNOPSIS...
A SERIES OF SPEED MAXIMA EJECTING NEWD ON ERN SIDE OF SLOWLY-
PROGRESSIVE WRN U.S. TROUGH WILL PRODUCE MULTIPLE EPISODES OF SVR
TSTMS OVER A FAIRLY BROAD SWATH OF THE CNTRL AND S CNTRL U.S.
THROUGH EARLY MON.

MAIN UPR VORT NOW OVER WY/CO SHOULD CONTINUE NE INTO THE DAKOTAS/NEB
LATER TODAY AS TRAILING/LOOSELY-ASSOCIATED SRN IMPULSE NOW IN NM
REACHES W TX. THE LATTER FEATURE SHOULD CONTINUE NE INTO THE LWR MO
VLY/WRN OZARKS BY 12Z MON...WHILE ADDITIONAL IMPULSES OF MORE SRN
ORIGIN MOVE ENE ACROSS WRN/CNTRL TX.

AT LWR LVLS...ERN PART OF MAIN SYNOPTIC SCALE FRONT NOW EXTENDING
FROM SW KS TO THE MID MS VLY SHOULD SURGE NE INTO WI AND THE UPR GRT
LKS BY EARLY MON AS A SFC WAVE DEVELOPS OVER SE NEB AND MOVES NE IN
ASSOCIATION WITH LEAD UPR IMPULSE. IN THE WAKE OF THE WAVE...
EXPECT TRAILING WRN PART OF THE FRONT WILL ACCELERATE SE ACROSS
WRN/NRN KS AND THE OK/NRN TX PANHANDLE REGION EARLY MON. FARTHER
S...STRONG/PERSISTENT SW FLOW ALOFT WILL MAINTAIN LEE LOW AND
TROUGH/DRY LINE OVER THE SRN HI PLNS.

...SRN PLNS INTO CNTRL KS...
SLOW EWD PROGRESSION OF WRN STATES TROUGH...AND ASSOCIATED ARRAY OF
SPEED MAXIMA...WILL MAINTAIN A BROAD CURRENT OF 55-65 KT MID LVL
SSWLY FLOW OVER MOST THE SRN AND CNTRL PLNS THROUGH THE PERIOD.
THUS...DEEP SHEAR WILL BE FAVORABLE FOR SUSTAINED STORMS/ SUPERCELLS
OVER A WIDE REGION. BUT SATELLITE LOOPS SUGGEST THE PRESENCE OF
NUMEROUS WEAK SHORT WAVE DISTURBANCES WITHIN THIS FLOW...IN ADDITION
TO THE MORE OBVIOUS ONES MENTIONED IN THE SYNOPSIS. THESE LIKELY
WILL MODULATE STORM DEVELOPMENT AND EVOLUTION ON THE MESOSCALE...AND
WILL ADD CONSIDERABLE COMPLEXITY TO THE GENERAL SCENARIO OUTLINED
BELOW.

ONE APPARENT IMPULSE...NOW IN CNTRL OK...APPEARS RESPONSIBLE IN PART
FOR RECENT INCREASE IN STORMS ALONG ADVANCING WARM FRONT IN CNTRL
KS. EXPECTED THIS ACTIVITY TO INCREASE BOTH NEWD AND SWWD ALONG
FRONT THROUGH THE MORNING AS STRONG/MOIST SLY LLJ CONTINUES TO
IMPINGE ON BOUNDARY.

A BIT LATER THIS MORNING THROUGH EARLY THIS AFTN...EXPECT THAT
ASCENT WITH STRONGER NM IMPULSE WILL HELP INITIATE STORMS ALONG LEE
TROUGH/DRY LINE FROM THE ERN TX PANHANDLE/NW OK SSW TO THE PERMIAN
BASIN. SFC HEATING ON WRN EDGE OF EXTENSIVE LOW CLOUD FIELD...AND
WEAK HEIGHT FALLS/MID LVL COOLING...SHOULD ALLOW THIS ACTIVITY TO
INCREASE IN COVERAGE/STRENGTH THROUGH LATE THIS AFTN/EVE.

COMBINATION OF STRONG INSTABILITY /SBCAPE TO 2000 J PER KG/ AND RICH
MOISTURE /PW 1.00-1.25 INCHES/ WITH 40-50 KT DEEP SWLY SHEAR SHOULD
SUPPORT SCTD SUSTAINED SUPERCELLS WITH SVR HAIL AND WIND.
INITIALLY...BACK-VEER PATTERN TO WIND PROFILES ACROSS THE SRN HI
PLNS /E.G AS IN 12Z MAF RAOB/ WILL COMPLICATE STORM STRUCTURE/ FAVOR
LINE SEGMENTS. ALTHOUGH THIS MAY LIMIT POTENTIAL FOR
TORNADOES...GIVEN STRENGTH OF SHEAR AND QUALITY OF MOIST INFLOW...AT
LEAST A CONDITIONAL TORNADO THREAT WILL EXIST.

BY LATE AFTN OR EARLY EVE...EXPECT THAT THE STORMS WILL HAVE EVOLVED
INTO SEVERAL LOOSELY-ORGANIZED CLUSTERS EXTENDING FROM CNTRL/SRN KS
THROUGH WRN/CNTRL OK INTO NRN/W CNTRL AND SW TX. EMBEDDED
SUPERCELLS WITHIN THESE CLUSTERS WILL CONTINUE TO POSE A THREAT FOR
SVR HAIL/WIND AND TORNADOES. THE TORNADO THREAT MAY ONCE AGAIN
INCREASE TOWARD SUNSET AND LATER AS SLY LLJ STRENGTHENS TO AOA 50
KTS.

GIVEN THE MAGNITUDE OF THE SHEAR AND THE BREADTH/QUALITY/STRENGTH OF
THE MOIST INFLOW...THE SVR THREAT MAY CONTINUE THROUGH LATE
TONIGHT/EARLY MON NEWD ACROSS ERN OK AND ERN KS. FARTHER S...OTHER
SVR STORMS/STORM CLUSTERS MAY CONTINUE TO EVOLVE OVER N
CNTRL...CNTRL...AND S CNTRL TX AS AFOREMENTIONED SRN STREAM
DISTURBANCES INTERACT WITH STRONG/MOISTURE RICH SLY FLOW.

...ERN KS TO UPR MS VLY/GRT LKS...
STORMS NOW FORMING N OF WARM FRONT WILL CONTINUE TO POSE A THREAT
FOR SVR HAIL. 50-60 KT SSWLY LLJ WILL BE MAINTAINED AND SHIFT NNE
TO THE UPR MS VLY AS LEAD SHORT WAVE IMPULSE EJECTS NEWD. GIVEN
STRENGTH OF THE LLJ...A RELATIVELY NARROW CORRIDOR OF RICH
MOISTURE SHOULD MOVE RAPIDLY NNE...WITH SFC DEWPOINTS IN THE LOWER
60S REACHING SERN MN/CNTRL WI BY MID-LATE AFTN. EXTENT OF
DESTABILIZATION ALONG THIS AXIS REMAINS UNCERTAIN DUE TO CLOUDS AND
LIKELIHOOD FOR ADDITIONAL ELEVATED CONVECTION. NEVERTHELESS...SOME
BOUNDARY LAYER WARMING WILL OCCUR IN WAKE OF MORNING RAIN...WITH
MLCAPE OF 500-1000 J/KG POSSIBLE. STORMS SHOULD INTENSIFY ALONG AND
POSSIBLY AHEAD OF FRONT FROM KS NEWD THROUGH IA AS BOUNDARY RETURNS
SEWD IN WAKE OF SFC WAVE.

STRONG WIND PROFILES WITH EJECTING IMPULSE AND ATTENDANT LLJ WILL
RESULT IN LARGE HODOGRAPHS /0-1 KM SRH 200-300 M2 PER S2/...WITH
SUFFICIENT DEEP SHEAR FOR ORGANIZED STORMS...LIKELY BROKEN LINES
WITH EMBEDDED BOWING SEGMENTS AND SUPERCELLS. THESE WILL POSE A
THREAT FOR DMGG WIND AND ISOLD TORNADOES/HAIL. THIS ACTIVITY MAY
MERGE WITH OTHER CLUSTERS MOVING/DEVELOPING NEWD ACROSS ERN KS AND
NW MO EARLY MON.

INSTABILITY WILL DECREASE GRADUALLY WITH NEWD EXTENT INTO NRN WI/UPR
MI...ISOLD SVR WIND GUSTS MAY OCCUR CLOSE TO STRONG LLJ EARLY MON.

...PARTS OF UPSTATE NY/NE PA/WRN MA AND CT...
SFC DEWPOINTS IN THE MID 50S WILL SPREAD E ACROSS THE PRE-FRONTAL
WARM SECTOR OVER SRN NY INTO SRN NEW ENGLAND. MODEST MID LVL LAPSE
RATES AROUND 6.5 C/KM ARE EXPECTED TO LIMIT DEGREE OF
DESTABILIZATION. HOWEVER...POTENTIAL WILL EXIST FOR A FEW
HIGH-BASED TSTMS THIS AFTN/EARLY EVE...WITH ACTIVITY SPREADING E
GIVEN 30-40 WLY MID LVL FLOW. STEEP LOW LEVEL LAPSE RATES/WELL
MIXED BOUNDARY LAYER SUGGESTS POSSIBILITY FOR A FEW STRONGER WIND
GUSTS.

..CORFIDI/HART/SMITH/MEAD.. 04/26/2009
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Adrian - your site is great, and will certainly help me rebuild my links.
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Ok, so I have a question, and you all need to be nice. All of the links on my computer (gathered for two years) were lost when the computer got replaced. One of the sites had all the different weather maps, you could choose surface conditions, precipitation, etc. I have been looking for the last little while, and can't seem to find it.

More specifically, looking for the map that shows the pressure gradient, to see what all these winds are about.

Thanks!
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Quoting PresidentialElection:


I have an A.A. in Meteorology, and I'm currently working on my second year to accquire my B.A. in meteorology as well, from FIU.


Congrats....I will be receiving my bachelor's in enviromental sciences this summer.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
PE: how did you get a AA degree in meteorology,if you don't know that 994mb would not usually be a Cane???,just curious,not trying to be malicious,my friend to the south!!!....
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if the storm heads north of the yucatan,the ssts's drop and sheer hightens,I don't see anything that would strengthen it if it moved north,maybe if it got pulled up by a trough,it might stregthen for a short while???
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Pandemics, hurricanes, volcanic eruptions...

At least the draft re-starts to bring smiles to many.

(Unless you're an Oakland Raider fan, I guess.)
Member Since: August 23, 2008 Posts: 7 Comments: 5300
PresidentialElection feel free to use my tropical links for feature reference this year.I have the Nogaps hourly windshear on there with the GFS 72hr from WU.You can also use FSU. CLICK HERE
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Quoting PresidentialElection:


What would intensify it, then weaken it, in the GOM?

Intensify: warmer waters, lower shear
Weaken: cooler waters, higher shear
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GFS thinks its mid-august lol, again remember this is way out in time though consistency is there iam still not buying it without futher model support. I did see a slightly favorable environment on some of the models.

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Quoting PresidentialElection:


What would intensify it, then weaken it, in the GOM?


Don't you have a degree?
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Quoting PresidentialElection:


994mb, that's a moderate cane, isn't it, 456?


moderate TS

Anything between 989-970 is typically a moderate cane
Member Since: July 24, 2005 Posts: 407 Comments: 19076

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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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