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Atlantic Tropical Action 2012 - Part I


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Hurricane season is here, and FSU scientists predict an active one

Scientists at the Florida State University Center for Ocean-Atmospheric Prediction Studies (COAPS) have released their fourth annual Atlantic hurricane season forecast, using a unique computer model with a knack for predicting hurricanes with unprecedented accuracy.

Hurricane season begins June 1 and runs through Nov. 30.

This year's forecast calls for a 70 percent probability of 10 to 16 named storms and five to nine hurricanes. The mean forecast is for 13 named storms, seven hurricanes, and an average accumulated cyclone energy — a measure of the strength and duration of storms — of 122. These numbers are based on 51 individual seasonal forecasts conducted since May 25, 2012, using sea surface temperatures predicted by National Oceanic and Atmospheric Administration.

The forecast mean numbers are slightly below the 1995-2010 average of 14 named storms and eight hurricanes, and reflect the possible emergence of El Niño conditions in the tropical Pacific and cooling surface water temperatures in the tropical North Atlantic.

"There is still uncertainty in the magnitude and timing of the emergence of the warming waters in the tropical Pacific along with the cooling of the tropical North Atlantic waters," said lead scientist Timothy LaRow. "These factors combined will to a large extent dictate the level of tropical activity."

LaRow and his colleagues at COAPS use a numerical climate model developed at Florida State to understand seasonal predictability of hurricane activity. The model is one of only a handful of numerical models in the world being used to study seasonal hurricane activity and is different from the statistical methods used by other seasonal hurricane forecasters. FSU is the only university in the United States that ussues a seasonal hurricane forecast using a global numerical atmospheric model.

The COAPS forecast is already gaining recognition for its accuracy only three years after its launch. The 2009 forecast predicted eight named storms and four hurricanes, and there ended up being nine named storms and three hurricanes that year. The 2010 forecast predicted 17 named storms and 10 hurricanes, and there were actually 19 named storms and 12 hurricanes. The 2011 forecast predicted an average of 17 named storms and nine hurricanes, and there were actually 19 named storms and seven hurricanes. Re-forecasts conducted using data since 1982 show that the model has a mean absolute error of 1.9 hurricanes and 2.3 named storms.

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Compared to Wunderground, this board is like an Ivy League library during finals week. That being said, I look forward to the stupidity when the GFS 300 hrs+ makes a swirl somewhere during hurricane quiet time.

Just from taking a quick look at the current intraseasonal state, it looks like the next shot for another Atlantic TC would be between June 23 and June 30... And that's being hopeful! Until then... I wouldn't buy any 300 + hrs GFS forecasts even if it looks like Katrina =P

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Euro shows a storm off the Carolinas day 8-10.

That would be awesome. Something developing off the SE Coast on an old front and heading North. Funny feeling it doesn't happen, but little unexpected gifts from nature is what makes weather fun.

msl_uv850_z500!Wind%20850%20and%20mslp!240!North%20America!pop!od!oper!public_plots!2012060212!!chart.gif

Be even cooler if the Euro looked like that in August...

2012152atsst.png

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That would be awesome. Something developing off the SE Coast on an old front and heading North. Funny feeling it doesn't happen, but little unexpected gifts from nature is what makes weather fun.

msl_uv850_z500!Wind%20850%20and%20mslp!240!North%20America!pop!od!oper!public_plots!2012060212!!chart.gif

Be even cooler if the Euro looked like that in August...

2012152atsst.png

Yeah not much potential unless It's 800 miles south

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Steve posted something I hadn't seen in a while at the KHOU-TV 11 local forum. About a hoped for change in 6 weeks of dryness for SETX as a front, an upper low, and shaprly increasing low and mid level moisture might come together over the lawns, but while it is early, CIMSS does show what appears to be a wave in the Mid-Atlantic, and, well, I love the CIMMS TPW animation.

BTW, our local private secotr pro-met has pointed out the utility of this for spotting incipient TCs. When one sees cyclonic rotation in the TPW animation, especially if somewhat protected from dry air immediately nearby, interesting things are coming, I have found the FSU Experimental site 700 mb theta-e animations a decent forecast of what the TPW may look like.

latest72hrs.gif

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Steve posted something I hadn't seen in a while at the KHOU-TV 11 local forum. About a hoped for change in 6 weeks of dryness for SETX as a front, an upper low, and shaprly increasing low and mid level moisture might come together over the lawns, but while it is early, CIMSS does show what appears to be a wave in the Mid-Atlantic, and, well, I love the CIMMS TPW animation.

BTW, our local private secotr pro-met has pointed out the utility of this for spotting incipient TCs. When one sees cyclonic rotation in the TPW animation, especially if somewhat protected from dry air immediately nearby, interesting things are coming, I have found the FSU Experimental site 700 mb theta-e animations a decent forecast of what the TPW may look like.

This is similar to how "the pouch" is identified in Mike Montgomery's Marsupial Paradigm. For anyone who is not familiar about what I am talking about, you can visit Mike Montgomery's homepage.

Just to sum it up: They use the Okubo Weiss (OW) Parameter to track the incipient vortex, which in essense, is a parameter that identifies circulation. They manually subtract out the mean westward propagation of the easterly wave (via linear estimation from a time-longitude plot), to identify the "pouch" in a lagrangian frame.

This methodology does a fantastic job indentifying circulations associated with developing tropical cyclones. The only downfall is it is reliant on different GCMs for forecasts (but then again, most forecasts are based off of GCMs). When and if they develop this methodology for ensembles, that's when the product will perform much better in my opinion. At the moment thuogh, it is a great tracking program, which is attributed to the use of the OW parameter.

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They are ok, especially W of 40W. SHAs still show that we are in a distinct +AMO/+TNA regime, there's a plus in OHC out there, surface SSTs were just negatively affected by the +NAO regime in winter and early spring. Since then it has been more of a neutral NAO one, and the time we got a brief -NAO period, a few weeks ago, SSTAs responded quickly. May will probably average ~0 in the TNA index, and 10 days from now we'll probably see very distinct +SSTAs in the MDR. Right now I would consider SSTAs as neutral with a positive outlook.

This verified pretty well. Pattern won't be as good from Jun 5-14 for strong warming, but some slow warming could still be possible, as I don´t foresee any strong Azores high in the medium range.

As for ENSO, some slight cooling will probably ensue next 2 weeks, diminishing any prospects of a significant effect of shear in the Atlantic tropics...as a matter of fact, the tropical Atlantic and the Caribbean have been on a lower than normal shear environment, and with the current big anticyclone near central america, this will continue for some time. Early season shear profiles usually spillover for the rest of the season.

gecarshr.png

getatshr.png

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JB Tweeting about "pattern recognition" Gulf development, Canadian (and NAM) almost tries to do something fairly short term from BoC, but Canadian doesn't show it getting done, not exactly sure what he is referring to.

Or the time frame.

EDIT TO ADD

June 10th-20th in another Tweet. Still see nothing obvious.

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JB Tweeting about "pattern recognition" Gulf development, Canadian (and NAM) almost tries to do something fairly short term from BoC, but Canadian doesn't show it getting done, not exactly sure what he is referring to.

Or the time frame.

He's talking about this weekend or early next week. For "pattern recognition," you'd really want the trough axis over the Four Corners, which isn't where it is modeled right now. As it is currently modeled, there would be 30-40 kts of westerly shear in the Western Gulf at that time. Development is unlikely, but not impossible, imo. Even if nothing forms, it looks like a soaker from IAH to MSY over that time frame.

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He's talking about this weekend or early next week. For "pattern recognition," you'd really want the trough axis over the Four Corners, which isn't where it is modeled right now. As it is currently modeled, there would be 30-40 kts of westerly shear in the Western Gulf at that time. Development is unlikely, but not impossible, imo. Even if nothing forms, it looks like a soaker from IAH to MSY over that time frame.

Disorganized deep moisture soakers sounds good to me.

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As Adam mentioned, shear is an issue across the Gulf but lowering pressures near the Bay of Campache and rather deep tropical moisture is pooling along with a stalled boundary along the Gulf Coast does tend to mildly focus attention in that area for a potential 'home grown' quick spin up of a sheared out mess. June does tend to favor that area ala Allison (2001)... :P

post-32-0-12727700-1338810942_thumb.jpg

post-32-0-85684000-1338810951_thumb.gif

post-32-0-97486800-1338811229_thumb.png

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As Adam mentioned, shear is an issue across the Gulf but lowering pressures near the Bay of Campache and rather deep tropical moisture is pooling along with a stalled boundary along the Gulf Coast does tend to mildly focus attention in that area for a potential 'home grown' quick spin up of a sheared out mess. June does tend to favor that area ala Allison (2001)... :P

Hi all,

The current evolution of convection within the tropics would favor tropical cyclogenesis over the West Pacific, with reduced favorability over the Eastern Pacific and Atlantic.

28.gif

The current snap shot of TRMM 3B42 rain rates (shaded) and 200 hPa Velocity Potential anomalies (henceforth VP200; contoured) shows the evolution of a wavenumber one pattern within the VP200 field. Positive VP200 anomalies (upper-level convergence; warm colored contours) are located over the Western Hemisphere and negative VP200 anomalies (upper-level divergence; cool colored contours) are over the Eastern Hemisphere. This wavenumber one pattern is consistent with the development of a coherent MJO signature.

In order to demonstrate the development of a coherent MJO signature, I have created a real-time multivariate MJO (RMM) index, similar to Wheeler and Hendon's (2004; henceforth WH04) RMM index. While WH04 calculates their EOFs by using upper and lower tropospheric zonal winds and outgoing longwave radiation (OLR), my index subsitudes OLR with VP200.

To illustrate the development of the new MJO signal:

kelvinPhase.png

Source: http://mikeventrice....ly.com/mjo.html

This diagram suggests that the MJO has very recently intensified to an amplitude greater than 1 sigma (inner circle = 1 sigma threshold) and is in RMM phase 3. RMM phase 3 is consistent with negative unfiltered VP200 anomalies over the eastern Indian-western Maritime and positive VP200 anomalies over the Western Hemisphere... consistent with the first figure posted above.

That being said, disturbances over the Atlantic are less likely to develop in the upcoming few weeks... with conditions becoming more favorable towards the end of June-early July. This would also suggests temperatures over the central eastern US should become above normal in the next 1-3 weeks.

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Mike,

Dr. Roundy's products are showing a Kelvin wave moving through 90-100W this weekend, which I assumed was the trigger for the potential cyclogenesis seen in the models. Over the last three years, since I started following Dr. Roundy's forecasts, these KW events have been able to overcome neutral, or even negative, MJO conditions. I'm not in the cyclogenesis camp right now, but the KW at least gives me pause. Since you are researching this stuff, I figured you might have a better idea than me.

P.S. I like the VP200 calculations. It's easier to diagnose than OLR.

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Hi all,

The current evolution of convection within the tropics would favor tropical cyclogenesis over the West Pacific, with reduced favorability over the Eastern Pacific and Atlantic.

The current snap shot of TRMM 3B42 rain rates (shaded) and 200 hPa Velocity Potential anomalies (henceforth VP200; contoured) shows the evolution of a wavenumber one pattern within the VP200 field. Positive VP200 anomalies (upper-level convergence; warm colored contours) are located over the Western Hemisphere and negative VP200 anomalies (upper-level divergence; cool colored contours) are over the Eastern Hemisphere. This wavenumber one pattern is consistent with the development of a coherent MJO signature.

In order to demonstrate the development of a coherent MJO signature, I have created a real-time multivariate MJO (RMM) index, similar to Wheeler and Hendon's (2004; henceforth WH04) RMM index. While WH04 calculates their EOFs by using upper and lower tropospheric zonal winds and outgoing longwave radiation (OLR), my index subsitudes OLR with VP200.

To illustrate the development of the new MJO signal:

Source: http://mikeventrice....ly.com/mjo.html

This diagram suggests that the MJO has very recently intensified to an amplitude greater than 1 sigma (inner circle = 1 sigma threshold) and is in RMM phase 3. RMM phase 3 is consistent with negative unfiltered VP200 anomalies over the eastern Indian-western Maritime and positive VP200 anomalies over the Western Hemisphere... consistent with the first figure posted above.

That being said, disturbances over the Atlantic are less likely to develop in the upcoming few weeks... with conditions becoming more favorable towards the end of June-early July. This would also suggests temperatures over the central eastern US should become above normal in the next 1-3 weeks.

Good stuff, thanks. Climo also favors the last week of June, with the W Carib and GoC being the usual suspects wrt cyclogenesis...a coherent MJO wave the last days of June, the first of July would certainly aid the process.

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