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Tropical Global Model Runs Discussion 2018

GaWx said:
Fwiw from Larry Cosgrove yesterday, Flo may not end up being the only high impact CONUS TC due to the possibility of something new and strong in a dangerous position in about 2 weeks:

“One of the complications is that while many of the forecast models had earlier been predicting a robust El Nino, what has actually happened in a positive neutral ENSO with a tendency to remain over and west of the International Dateline. This alignment, called a Modoki event, will permit tropical cyclone development in the Gulf of Mexico, Caribbean and Sargasso Seas (as shearing wind profiles mostly stay along and off of the Pacific shoreline. Since the ensemble members of the various equations show a heat ridge presence over the southern and eastern sections of the U.S. in the 11 - 15 day, any transition to colder air might be enhanced by a combination of a warm-core feature and a frontal structure, the likes of which are shown in the analog outlooks which foresee a cooler turn in the eastern third of the country on the last day of September.”

Don’t shoot the messenger.
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:(:(:(
 
Looking strictly at FL H hits from 9/21-10/31 W Caribbean geneses since 1851, here are the longest periods without a H hit:
1. 18 years (1969-1987)
2. 14 years (1851-1864)
3. 13 years (1951-1963)
4. 12 years (2006-2017)
5. 10 years (1883-1892)

On average, FL has gotten a H hit every 5.5 years just from W Caribbean TCs forming 9/21-10/31! (30 hits in 167 years)
 
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GaWx said:
Looking strictly at FL H hits from 9/21-10/31 W Caribbean geneses since 1851, here are the longest periods without a H hit:
1. 18 years (1969-1987)
2. 14 years (1851-1864)
3. 13 years (1951-1963)
4. 12 years (2006-2017)
5. 10 years (1883-1892)

On average, FL has gotten a H hit every 5.5 years just from W Caribbean TCs forming 9/21-10/31!
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You just ruined waking up from a nap ... o_O
LOL ...
 
GFS does a Hurricane Hazel redux day 14 and 15. I'm desperate for fall and that's the only reason I'm looking at a model past 10 days, let alone the gfs. It was pretty cool to see, big front sweeps through, blocking gets established behind it and cane shoots up the seaboard from the Caribbean
 
NCSNOW said:
GFS does a Hurricane Hazel redux day 14 and 15. I'm desperate for fall and that's the only reason I'm looking at a model past 10 days, let alone the gfs. It was pretty cool to see, big front sweeps through, blocking gets established behind it and cane shoots up the seaboard from the Caribbean
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Good thing it’s the gfs.


Sent from my iPhone using Tapatalk
 
ForsythSnow said:
Bad thing is that the GFS and the FV3 have some long range tropical development in the Caribbean that should be watched for development later down the road in a couple of weeks.
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I hope that doesn't happen, but they did pretty good picking up on Florence a ways out.
 
Getting into fantasy land on the Euro but the ECMWF has been superb w/ genesis (in general) this season, the Fv3 & GFS have struggled in this department & are biased towards Central America in the long range

ecmwf_uv850_vort_atl_11 (2).png
 
Webberweather53 said:
Getting into fantasy land on the Euro but the ECMWF has been superb w/ genesis (in general) this season, the Fv3 & GFS have struggled in this department & are biased towards Central America in the long range

View attachment 6457
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The good news is that by Sep 27th climo says it would be very difficult for an E Atlantic TC to make it all the way to the Conus. I’ll check but I believe that very few TCs that become TSs E of 50W on or after 9/25 have made it to the Conus. It is no more than a handful since way back in 1851 per records anyway. By that time, I’m already focused on the W Caribbean.
 
GaWx said:
The good news is that by Sep 27th climo says it would be very difficult for an E Atlantic TC to make it all the way to the Conus. I’ll check but I believe that very few TCs that become TSs E of 50W on or after 9/25 have made it to the Conus. It is no more than a handful since way back in 1851 per records anyway. By that time, I’m already focused on the W Caribbean.
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In a year like this where we have strong/poleward subtropical highs, climo is less relevant because the background state is pushing us towards longer-tracked TCs. The chances generally increase for a recurve the deeper we get into ASO because the westerlies are deeper and more extensive but it's far from a guarantee.
 
In a season like this where we have a strong West Africa Monsoon, subseasonal coupling even in late September/early October can be sufficient to trigger another TC or two east of the Lesser Antilles as the EPS/Euro are hinting at after this week. There's a Convectively Coupled Kelvin Wave passing thru South America now that'll move over Africa in the medium range, temporarily rejuvenating any African Easterly Waves in its vicinity.

28 (1).gif
eps_tropcyc_prob_20_atlantic_264 (4).png

ecmwf_uv850_vort_atl_10 (2).png
 
Webberweather53 said:
In a season like this where we have a strong West Africa Monsoon, subseasonal coupling even in late September/early October can be sufficient to trigger another TC or two east of the Lesser Antilles as the EPS/Euro are hinting at after this week. There's a Convectively Coupled Kelvin Wave passing thru South America now that'll move over Africa in the medium range, temporarily rejuvenating any African Easterly Waves in its vicinity.
View attachment 6461
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Fair enough and I see the good number of 12Z EPS members with genesis. However, just about all of these members weaken by 30W.

I just rechecked the data. Only one TS+ that formed east of 50W 9/25+ made it to the CONUS going back to 1851 and that was on 9/25 in 1893. So, I'm not going to get concerned about any genesis that far east around 9/25 like the Euro/EPS shows getting to the CONUS. I'm not saying it would be impossible. Who knows? Maybe it is time for a very late 1 in 100 year track. Flo moved NW the furthest E of any TC on record back to 1851 that later hit the CONUS. So, never say never. However, I am saying that based on more than 100 years of history that the chance is very slim since 1893 was the last time. The next earliest late genesis date E of 50W that hit the US was 9/21 (two of them..1966 and 2002).

Maybe it isn't as slim a chance that I think due to GW, which I think you're suggesting. I'll give you that as a possibility.
 
Of arguably more concern, with the ITCZ generally progressing equatorward in the summer hemisphere, the rainy season will make a triumphant return in Central America, and thus there's going to be a major uptick in large-scale upward motion over the Western Hemisphere as we turn the page into October. The JMA, GEFS, & EPS all agree on this transpiring, and it'll likely piggy-back onto one of the pre-existing Convectively Coupled Kelvin Waves (CCKWs) that's currently in the eastern hemisphere. The chance of a tropical cyclone forming in either the Northeastern Pacific, Caribbean Sea, and/or south-central Gulf of Mexico during the first half of October will be much higher than climatology given how convectively active Central America is forecast to become. This will be something to watch in the coming weeks.

JMA
Screen Shot 2018-09-17 at 6.03.49 PM.png
GFS Ensemble
diagram_40days_forecast_GEFSBC_member.gif

EPS
ECMF_phase_51m_small (1).gif
 
Webberweather53 said:
Of arguably more concern, with the ITCZ generally progressing equatorward in the summer hemisphere, the rainy season will make a triumphant return in Central America, and thus there's going to be a major uptick in large-scale upward motion over the Western Hemisphere as we turn the page into October. The JMA, GEFS, & EPS all agree on this transpiring, and it'll likely piggy-back onto one of the pre-existing Convectively Coupled Kelvin Waves (CCKWs) that's currently in the eastern hemisphere. The chance of a tropical cyclone forming in either the Northeastern Pacific, Caribbean Sea, and/or south-central Gulf of Mexico during the first half of October will be much higher than climatology given how convectively active Central America is forecast to become. This will be something to watch in the coming weeks.

JMA
View attachment 6464
GFS Ensemble
View attachment 6465

EPS
View attachment 6466
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Until you get a roofer, let's hope not ... :cool:
 
Webb is that what the gfs been keying on as well? Larry mentioned it last night I think too with watching SW Caribbean for possible TC development. 18z has a concearning system post d10 in Caribbean, and hints of development with previous runs too. Is the phase 8/1 in MJO a good phase for increase TC development?
gfs_z850_vort_atl_41.png gfs_z850_vort_atl_51.png
 
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