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Tropical Global Model Runs Discussion 2017

Webberweather53 said:
UKMET develops both 91L & what's liable to be future 92L to its west and the next wave behind it by day 5-6 and thus has 3 TCs simultaneously in the MDR
View attachment 850


The European develops the broad monsoon low in front of 91L, doesnt develop 91L, but then develops the next wave behind it
View attachment 851

The CMC briefly develops the system in front of 91L, destroys 91L and then produces a TC from the next AEW immediately behind 91L
View attachment 852

The GFS now caved to the Euro/UKMET solution and develops the system in front of 91L but shows nothing thereafter
View attachment 853

The JMA on the other hand develops the system in front of 91L, and the next 2 waves behind it, thus also leaving the Atlantic with 3 TCs at once like the UKMET although it got there much differently...
View attachment 854

Big takeaway here: As is usually the case with TCs that come out of the monsoon trough, the global models are having a very difficult time picking out which disturbance to hone in on, which means deterministic and even ensemble solutions are bound to vary wildly for the next several days until a TC has developed or is very close to doing so. While the models are liable to remain inconsistent til then, that doesn't mean they're necessarily mean that the uncertainty is so high that we can assume nothing will transpire (which seems very unlikely atm) or negate the fact that the large scale environment is very conducive to TCG and intensification over the Atlantic MDR. As I mentioned in another thread, details like this matter in the long run for the US, and as the planetary wave configuration reshuffles and ridging begins to dominate eastern North America by week 2, all individuals should remain vigilant for rapidly changing weather conditions and forecasts as we're liable to see a heightened amount of tropical cyclone activity over the western Atlantic
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Wow, thanks Webb. You and Larry are truly appreciated for the knowledge yall bring to the table. Also SD, and Charlie thanks to yall also for putting up with my dumb questions over the years on here, lol. I've learned alot from yall to.
 
Webberweather53 said:
This CCKW passing over the eastern Atlantic and 91L is an absolute monster, don't see 3.0 sigma CCKWs but once maybe twice a year over a given location... It's co-existence w/ an MJO pulse over the western hemisphere is largely to blame for this CCKW having such profound amplitude
View attachment 856
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I have no clue if I'll even understand the answer to the question I'm about to ask but I'm gonna ask anyway and give it a shot Lol...

Eric the map you posted on Saturday showed 1.5 CCKW and today it's 3.0, was it the MJO impulse that caused such a drastic increase (if that is in fact actually a drastic increase). Just curious where do you get that information, is that your map or derived from another source? Thanks man!
 
metwannabe said:
I have no clue if I'll even understand the answer to the question I'm about to ask but I'm gonna ask anyway and give it a shot Lol...

Eric the map you posted on Saturday showed 1.5 CCKW and today it's 3.0, was it the MJO impulse that caused such a drastic increase (if that is in fact actually a drastic increase). Just curious where do you get that information, is that your map or derived from another source? Thanks man!
Click to expand...

Ok, I'll do my best. The map is from Mike Ventrice's website, and he uses wavenumber frequency filtering that essentially amounts to utilizing a fourier transform (which converts raw, noisy data into sinusoidal functions) over a time window of when CCKWs are most prevalent (usually several days to a few weeks) and uses a wavenumber-frequency domain to filter out again higher and/or lower frequency noise likely not attributable to CCKWs and sort for wavenumbers (i.e. the number of CCKWs usually observed on the globe at one time), which is usually between 2 and about 7.
Here's an example of a wavenumber frequency domain which choses typical frequencies and wavenumbers of various Equatorial wave types including the MJO, Kelvin, mixed rossb- gravity waves (MRGs) and inertio-gravity (IG) waves...
Screen Shot 2017-08-14 at 11.46.46 AM.png


Convectively Coupled Kelvin Waves (CCKWs) (“Super-cloud clusters”) comprise a significant proportion of the cloudiness, upward motion, and convective envelope associated with the MJO. The dynamical structures and amplitude of CCKWs have been found to increase when they are collocated with the convectively active phase of the MJO. This makes sense given that moist convection serves as a primary regulator of equatorial wave phase speeds by modifying the pressure and wind perturbations associated with them and increases (decreases) in convection lead to higher amplitude convective coupled (CC) equatorial waves propagate, which propagate slower (faster) because the accompanying convection is often found in the posterior portion (backside/in the wake of) of these CC waves. Therefore it should be no surprise that CCKW phase speed is typically slower underneath the convectively active phase of the MJO and in the Indo-West Pacific warm pool region (7-15 m/s) versus the western hemisphere & Africa (14-20 m/s) where background convection is typically less frequent. Kiladis (2009) suggests that the moist-CCKW as we observe in the real world 3 is slower than the theoretical speeds for a dry CCKW because the effective static stability of the atmosphere is reduced (condensational heating/cooling cancels out most if not all the temperature change attributed to vertical motion attributable to the CCKW).

Here's an idealized diagram of a theoretical Kelvin Wave (which bears a lot of similarities to real CCKWs) showing the axisymmetrical pressure perturbations centered about the equator and the concomitant convection
Screen Shot 2017-08-14 at 11.54.10 AM.png
 
metwannabe said:
I have no clue if I'll even understand the answer to the question I'm about to ask but I'm gonna ask anyway and give it a shot Lol...

Eric the map you posted on Saturday showed 1.5 CCKW and today it's 3.0, was it the MJO impulse that caused such a drastic increase (if that is in fact actually a drastic increase). Just curious where do you get that information, is that your map or derived from another source? Thanks man!
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So in short yes that's a pretty drastic increase, these kelvin filtered VP200 anomalies are standardized, therefore a change in VP200 anomalies of 1.5 sigma as we've observed the past few days when we're already at 1.5 sigma is more significant than when they're close to zero and on average a 3.0 sigma CCKW is observed about once-twice a year over a given geographic location on the globe. Also, yes the MJO definitely provided a big boost to this CCKW (in fact it's arguable that the MJO in the western hemisphere may be more adequately represented as a moist, slow moving CCKW), and you'll probably notice that this CCKW strengthened a lot further to the east over the Eastern Atlantic and South America as opposed to the eastern Pacific with the last CCKW as was the case a little over a week ago. This is largely because the MJO has also moved to the east...
 
Webberweather53 said:
Ok, I'll do my best. The map is from Mike Ventrice's website, and he uses wavenumber frequency filtering that essentially amounts to utilizing a fourier transform (which converts raw, noisy data into sinusoidal functions) over a time window of when CCKWs are most prevalent (usually several days to a few weeks) and uses a wavenumber-frequency domain to filter out again higher and/or lower frequency noise likely not attributable to CCKWs and sort for wavenumbers (i.e. the number of CCKWs usually observed on the globe at one time), which is usually between 2 and about 7.
Here's an example of a wavenumber frequency domain which choses typical frequencies and wavenumbers of various Equatorial wave types including the MJO, Kelvin, mixed rossb- gravity waves (MRGs) and inertio-gravity (IG) waves...
View attachment 858


Convectively Coupled Kelvin Waves (CCKWs) (“Super-cloud clusters”) comprise a significant proportion of the cloudiness, upward motion, and convective envelope associated with the MJO. The dynamical structures and amplitude of CCKWs have been found to increase when they are collocated with the convectively active phase of the MJO. This makes sense given that moist convection serves as a primary regulator of equatorial wave phase speeds by modifying the pressure and wind perturbations associated with them and increases (decreases) in convection lead to higher amplitude convective coupled (CC) equatorial waves propagate, which propagate slower (faster) because the accompanying convection is often found in the posterior portion (backside/in the wake of) of these CC waves. Therefore it should be no surprise that CCKW phase speed is typically slower underneath the convectively active phase of the MJO and in the Indo-West Pacific warm pool region (7-15 m/s) versus the western hemisphere & Africa (14-20 m/s) where background convection is typically less frequent. Kiladis (2009) suggests that the moist-CCKW as we observe in the real world 3 is slower than the theoretical speeds for a dry CCKW because the effective static stability of the atmosphere is reduced (condensational heating/cooling cancels out most if not all the temperature change attributed to vertical motion attributable to the CCKW).

Here's an idealized diagram of a theoretical Kelvin Wave (which bears a lot of similarities to real CCKWs) showing the axisymmetrical pressure perturbations centered about the equator and the concomitant convection
View attachment 859
Click to expand...
2 things real quick, 1 just glancing at this on my phone and that is one heck of an explanation can't wait to delve into it more when I get on a computer and 2 the comment about my understanding was in no way directed at your response but rather at my own inability to comprehend. Thanks webb

Sent from my SM-G920V using Tapatalk
 
metwannabe said:
2 things real quick, 1 just glancing at this on my phone and that is one heck of an explanation can't wait to delve into it more when I get on a computer and 2 the comment about my understanding was in no way directed at your response but rather at my own inability to comprehend. Thanks webb

Sent from my SM-G920V using Tapatalk
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Are you saying you are a normal simple minded individual...LOL!
 
metwannabe said:
2 things real quick, 1 just glancing at this on my phone and that is one heck of an explanation can't wait to delve into it more when I get on a computer and 2 the comment about my understanding was in no way directed at your response but rather at my own inability to comprehend. Thanks webb

Sent from my SM-G920V using Tapatalk
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Sure thing, no problem! I need to read up a little bit more on some of the intricacies of their methodology but hopefully I was able to convey the gist of it to you.
 
The 18Z GFS has all 3; destroys 91L, to be 92L goes northward, and to be 93L heads for the Caribbean as a weak TS.
gfs_z850_vort_atl_16.png
 
GFS has a Matthew-type track at 276 hours from something... hurricane near Cape Canaveral

then rides up the coast through Daytona Beach, Jacksonville, Savannah, and ending up near Charleston lol
 
Brent said:
GFS has a Matthew-type track at 276 hours from something... hurricane near Cape Canaveral

then rides up the coast through Daytona Beach, Jacksonville, Savannah, and ending up near Charleston lol
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This is definitely not a laughing matter but we all know it won't actually happen exactly this way on this day and very likely not even close, if it would even exist at all then. My area has been hit hard many dozens of times over the years by models (so I generally take them in stride if many days out) but actually hit only once by a H during these same years (once was way more than enough). Fortunately we can handle even the worst model hits pretty well. It is just the real hits like Matthew that are a challenge.
 
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