ATL: LAURA - Post-Tropical - Discussion

[drewschmaltz]

I think the moral of the story tonight isn't the exact specifics of these runs - more just that the setup is starting to look dangerous.

[GeneratorPower]

I think the moral of the story tonight isn't the exact specifics of these runs - more just that the setup is starting to look dangerous.

Exactly.

[Deshaunrob17]

I'm not buying the models' sudden turn (or more like initialized immediate movement) northwest; the western vortex, and indeed the overall Invest, is moving west. Either way, if this avoids a Georges-like track and skirts south into the Caribbean or misses the islands to the north, I think we'll see major Hurricane Laura by next week. HWRF might be bullish on intensity, but it nailed 2017 (and Irma specifically), and I'm getting Irma vibes from this one.

Overall I wouldn't be too conservative with this system. Every once in awhile, seasons come along where SSTs and atmospheric conditions are so favourable that you end up being more right than not simply by betting the more extreme outcomes will happen (even if you do end up looking like a hypecaster), particularly if SSTs are warm enough to allow extreme outcomes (which they are, in 98L's path). 2005 and 2017 are examples of this, and I believe all the indications are there that 2020 will be such a season. I'm willing to bet this will be the first major hurricane, and the first major hurricane to threaten land, of the season.

00z icon surely gave me that Irma vibes

[Hurricane Mike]

I'm not buying the models' sudden turn (or more like initialized immediate movement) northwest; the western vortex, and indeed the overall Invest, is moving west. Either way, if this avoids a Georges-like track and skirts south into the Caribbean or misses the islands to the north, I think we'll see major Hurricane Laura by next week. HWRF might be bullish on intensity, but it nailed 2017 (and Irma specifically), and I'm getting Irma vibes from this one.

Overall I wouldn't be too conservative with this system. Every once in awhile, seasons come along where SSTs and atmospheric conditions are so favourable that you end up being more right than not simply by betting the more extreme outcomes will happen (even if you do end up looking like a hypecaster), particularly if SSTs are warm enough to allow extreme outcomes (which they are, in 98L's path). 2005 and 2017 are examples of this, and I believe all the indications are there that 2020 will be such a season. I'm willing to bet this will be the first major hurricane, and the first major hurricane to threaten land, of the season.

I agree. In fact, I could foresee a "Major" Hurricane Laura, a more-moderate Hurricane Marco near TX/Northern Mexico (long before Laura gets to FL btw, I don't buy two storms together in the GOM), and then the monster wave off Africa becomes "Major" Hurricane Nana.

[Hybridstorm_November2001]

I think the moral of the story tonight isn't the exact specifics of these runs - more just that the setup is starting to look dangerous.

Exactly.

Indeed, my aunt and uncle (who still reside in South Florida but are elderly now) tell me they are concerned (they're "model watchers"). In many ways I think they never recovered from our experience with Andrew in 1992 (they have been very cautious ever since), 2004 - 2006 and the last two years didn't help ease their jittery nerves any.

[HurricaneEdouard]

I'm not buying the models' sudden turn (or more like initialized immediate movement) northwest; the western vortex, and indeed the overall Invest, is moving west. Either way, if this avoids a Georges-like track and skirts south into the Caribbean or misses the islands to the north, I think we'll see major Hurricane Laura by next week. HWRF might be bullish on intensity, but it nailed 2017 (and Irma specifically), and I'm getting Irma vibes from this one.

Overall I wouldn't be too conservative with this system. Every once in awhile, seasons come along where SSTs and atmospheric conditions are so favourable that you end up being more right than not simply by betting the more extreme outcomes will happen (even if you do end up looking like a hypecaster), particularly if SSTs are warm enough to allow extreme outcomes (which they are, in 98L's path). 2005 and 2017 are examples of this, and I believe all the indications are there that 2020 will be such a season. I'm willing to bet this will be the first major hurricane, and the first major hurricane to threaten land, of the season.

I agree. In fact, I could foresee a "Major" Hurricane Laura, a more-moderate Hurricane Marco near TX/Northern Mexico (long before Laura gets to FL btw, I don't buy two storms together in the GOM), and then the monster wave off Africa becomes "Major" Hurricane Nana.

Agreed. Climatologically, we've reached the part of the season where hyperactive seasons go crazy, and it is not improper to begin to lean into more bullish predictions regarding Invests. After all, as I'm sure anyone who's been tracking storms for a long time on this board knows, most of the major hurricanes were fairly obvious very early on (e.g. the imminent explosive intensifications of Wilma and Patrica were obvious to many Storm2kers due to their extremely cold cloudtops, Dean and Irma were obvious to the HWRF and the bulls were right on those); we don't have to signal how sober and sensible we are by sounding conservative, if that is statistically less accurate! (Not saying anyone is in this thread, by the way, and indeed they're not, just a general pattern that I've noticed on forums like these!)

[Monsoonjr99]

This feels like pre-Isaias all over again. I wonder if this will be a theme this season thanks to the overamplified West African Monsoon. Broad waves struggling to consolidate their competing vortmaxes in the MDR only to develop further west and pose a greater threat to land.

[TheStormExpert]

This feels like pre-Isaias all over again. I wonder if this will be a theme this season thanks to the overamplified West African Monsoon. Broad waves struggling to consolidate their competing vortmaxes in the MDR only to develop further west and pose a greater threat to land.

Yeah as if Isaias wasn’t a headache of a storm to track.

[CrazyC83]

I have more Ike vibes than Irma vibes here. This ridge is supposed to build in and really be stout. That could delay any turn. One issue could be land interaction with the Greater Antilles.

[Nuno]

I have more Ike vibes than Irma vibes here. This ridge is supposed to build in and really be stout. That could delay any turn. One issue could be land interaction with the Greater Antilles.

I'm inclined to also agree with this. I remember Irma's initially modeling had recurves well east of Florida. This could shift further south still given this ridge.

[Shell Mound]

I have more Ike vibes than Irma vibes here. This ridge is supposed to build in and really be stout. That could delay any turn. One issue could be land interaction with the Greater Antilles.

The upcoming pattern is rather dissimilar to that which coincided with Ike’s (2008) passage, including its southward dip into Cuba and entry into the Gulf of Mexico (GoM). I looked at ESRL’s averaged 500-mb daily composite anomalies for the period (range) of 5–10 September 2008, during which Ike dipped southward and traversed Cuba while en route to the GoM. Notably, while both Ike and 98L will be nearing the mainland U.S. during a -NAO, in 2008 the -NAO was east-based, with blocking centred east of Greenland, near Jan Mayen, whereas in 2020 it is going to be west-based, that is, centred over western Greenland and the Labrador Sea, during the period of 20–25 August. Additionally, unlike in 2008, the Sonoran heat ridge and its extension will play a prominent role, given the likelihood of a trough over or just west of California, along with the near-neutral EPO, which was strongly negative in 2008. Therefore, the Western Atlantic Ridge (WAR), while stout, will be situated farther south and be more zonally oriented than in 2008, that is, its primary axis will be oriented from east to west rather than from north to south. There will be multiple shortwaves or impulses rotating around the base of the Hudson Bay vortex, particularly by days six and seven, when 98L will likely be very close to or over South Florida, at least longitudinally. Therefore, while 98L is likely to pose a threat to the south-central Bahamas and South Florida, it is unlikely to proceed into the GoM as far west as Ike did. In fact, the upcoming pattern would seemingly favour a fairly sharp northward turn over the eastern GoM or the west coast of the FL peninsula, after an initial landfall somewhere in Southeast Florida, probably around Miami. (This also explains why I wouldn’t necessarily side with the modelled solutions that show a landfall over the Keys, as opposed to one in the Miami area. I also wouldn’t completely discard the notion that 98L could miss the U.S. to the east, though that solution may be becoming increasingly remote, given trends toward a stronger WAR.)

https://psl.noaa.gov/tmp/composites/compday.eP1aXMfIDj.gif
https://www.tropicaltidbits.com/analysis/models/ecmwf-ens/2020081812/ecmwf-ens_z500a_namer_8.png

For the purpose of comparison, here is the setup for Irma (2017), which was much more similar to that of Ike than that of 98L:

https://psl.noaa.gov/tmp/composites/compday.EHHDZmvUl9.gif

Andrew (1992):

https://psl.noaa.gov/tmp/composites/compday.OPiGzdBKLt.gif

Betsy (1965):

https://psl.noaa.gov/tmp/composites/compday.cnt7rpC9qU.gif

Donna (1960):

https://psl.noaa.gov/tmp/composites/compday.zRCkauJdki.gif

Yet another comparison can be made, using the 1949 Florida hurricane as an example:

https://psl.noaa.gov/tmp/composites/compday.FZNnUFHRWD.gif

1947 Fort Lauderdale hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.0.57.3.gif

1945 Homestead hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.0.59.0.gif

1935 Labor Day hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.1.0.34.gif

1933 Treasure Coast hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.0.58.21.gif

1928 Okeechobee hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.1.1.20.gif

1926 Miami hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.0.59.36.gif

Out of all these MH impacts in South FL, none coincided with an expansive Sonoran heat ridge centred in the Four Corners.

For the record, I’ll also throw in the 1919 Florida Keys hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.1.9.11.gif

[AtlanticWind]

https://www.star.nesdis.noaa.gov/GOES/s ... &length=24

Looks healthier tonight.

[Kingarabian]

Looking pretty good tonight for sure:


Nice banding to the S/SW. Behaving like an established TC.

[Shell Mound]

I have more Ike vibes than Irma vibes here. This ridge is supposed to build in and really be stout. That could delay any turn. One issue could be land interaction with the Greater Antilles.

The upcoming pattern is rather dissimilar to that which coincided with Ike’s (2008) passage, including its southward dip into Cuba and entry into the Gulf of Mexico (GoM). I looked at ESRL’s averaged 500-mb daily composite anomalies for the period (range) of 5–10 September 2008, during which Ike dipped southward and traversed Cuba while en route to the GoM. Notably, while both Ike and 98L will be nearing the mainland U.S. during a -NAO, in 2008 the -NAO was east-based, with blocking centred east of Greenland, near Jan Mayen, whereas in 2020 it is going to be west-based, that is, centred over western Greenland and the Labrador Sea, during the period of 20–25 August. Additionally, unlike in 2008, the Sonoran heat ridge and its extension will play a prominent role, given the likelihood of a trough over or just west of California, along with the near-neutral EPO, which was strongly negative in 2008. Therefore, the Western Atlantic Ridge (WAR), while stout, will be situated farther south and be more zonally oriented than in 2008, that is, its primary axis will be oriented from east to west rather than from north to south. There will be multiple shortwaves or impulses rotating around the base of the Hudson Bay vortex, particularly by days six and seven, when 98L will likely be very close to or over South Florida, at least longitudinally. Therefore, while 98L is likely to pose a threat to the south-central Bahamas and South Florida, it is unlikely to proceed into the GoM as far west as Ike did. In fact, the upcoming pattern would seemingly favour a fairly sharp northward turn over the eastern GoM or the west coast of the FL peninsula, after an initial landfall somewhere in Southeast Florida, probably around Miami. (This also explains why I wouldn’t necessarily side with the modelled solutions that show a landfall over the Keys, as opposed to one in the Miami area. I also wouldn’t completely discard the notion that 98L could miss the U.S. to the east, though that solution may be becoming increasingly remote, given trends toward a stronger WAR.)

https://psl.noaa.gov/tmp/composites/compday.eP1aXMfIDj.gif
https://www.tropicaltidbits.com/analysis/models/ecmwf-ens/2020081812/ecmwf-ens_z500a_namer_8.png

For the purpose of comparison, here is the setup for Irma (2017), which was much more similar to that of Ike than that of 98L:

https://psl.noaa.gov/tmp/composites/compday.EHHDZmvUl9.gif

Andrew (1992):

https://psl.noaa.gov/tmp/composites/compday.OPiGzdBKLt.gif

Betsy (1965):

https://psl.noaa.gov/tmp/composites/compday.cnt7rpC9qU.gif

Donna (1960):

https://psl.noaa.gov/tmp/composites/compday.zRCkauJdki.gif

Yet another comparison can be made, using the 1949 Florida hurricane as an example:

https://psl.noaa.gov/tmp/composites/compday.FZNnUFHRWD.gif

1947 Fort Lauderdale hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.0.57.3.gif

1945 Homestead hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.0.59.0.gif

1935 Labor Day hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.1.0.34.gif

1933 Treasure Coast hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.0.58.21.gif

1928 Okeechobee hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.1.1.20.gif

1926 Miami hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.0.59.36.gif

Out of all these MH impacts in South FL, none coincided with an expansive Sonoran heat ridge centred in the Four Corners.

For the record, I’ll also throw in the 1919 Florida Keys hurricane:

https://psl.noaa.gov/tmp/composites/compday.83.186.39.80.231.1.9.11.gif

Would it be valid to conclude, based on these examples, that 98L won’t hit FL and/or the Bahamas if it becomes a robust hurricane within the next three to five days, given that none of the MH impacts listed above coincided with a west-based -NAO, a strong Hudson Bay vortex, northwesterly flow over the Northeastern U.S., and a strong Sonoran heat ridge centred in the Four Corners region? Since west-based -NAOs do not seem to be very conducive to MH landfalls in South FL, will its presence during the closest possible approach of 98L indicate that it will miss South FL and the mainland U.S. to the east? Is my sample size sufficiently large?

At this stage, here are my preliminary thoughts on 98L:

1. 98L will likely gradually organise, becoming a TS (either Marco or Laura, given that 97L could develop faster than models indicate as well) by day two.
2. 98L is likely to head generally WNW, pass just north of the Leeward Islands, and approach hurricane status while north of Puerto Rico by day four.
3. At this point two possibilities become equally plausible, both involving a rapidly strengthening 98L becoming a major hurricane. a) 98L, rapidly organising into a powerful hurricane, nears or passes over part of the Turks and Caicos Islands. From there it turns northwestward, northward, and then northeastward, curving OTS between the U.S. East Coast and Bermuda. b) 98L, rapidly organising into a powerful hurricane, continues WNW into the south-central Bahamas, makes landfall as a major hurricane near Miami, FL, and then curves northwestward and northward into the Tampa Bay area and the Big Bend of Florida near Cedar Key. At this time these two scenarios I esteem the most likely, and I give each of them a 50/50 likelihood of occurrence.

[SFLcane]

Wow this is a go folks looks much better organized this morning.

[Sciencerocks]

[NXStumpy_Robothing]

As many models expected, the eastern lobe has caved to the influence of the western lobe and is now being pulled into the rapidly-developing western circulation, as evidenced by low to mid-level vorticity analysis. 98L may ultimately claim the name Laura, though 97L looks pretty decent as well.

With the competing vortmaxes now in the process of coalescing, TCG within the next 12 to 24 hours looks quite likely. Pretty much right on schedule. We'll see where it manages to end up in the coming days, and how much of a westward shift may be caused by that much weaker vortmax out to the west of 98L.

Stay safe, everyone.

[Steve H.]

Somehow I'm not convinced about 98L. Something seems wrong with this feature. Looked good right out of the gate a few days ago and I thought we'd have a TS by now. Maybe the competing vortices had something to do with the slow growth. I told someone a few days ago this was going to be the big one to watch here in the SE US. Something seems to be missing. Maybe the Euro is on to it. Not sure. It has always looked like it will crank, but then doesn't. We'll see what today brings.

[Chemmers]

Looking very good on satellite this morning, think it will be a td or storm today

[GCANE]

Looking like a strong TUTT to the NW, which will retrograde to an UL trough, will shred part of this and then the islands will take another chunk out of it.