ATL: ISAIAS - Models

[STRiZZY]

The Euro went completely wacko? It was maybe 50mi north of 12z. That's not far off of it's previous few runs tbh.
It's just those 50 some odd miles put in it a more favorable position in regards to the Greater Antilles and gave it a little room to breathe.

Well granted there is a 400 mile difference when it's sitting off Tampa Bay vs Cancun in the 12z. The behavior is quite different between the 2 runs, the euro also bumped it's intensity quite a bit compared to previous runs even in the short term. The entire agenda the models gave to us about the storm has now been flipped on it's head.

You'll have that when one run is 50 mi's south and traverses 1,100mi + of land and dies and the other traverses just north of that and stays alive.

[STRiZZY]

0z Drenched the Tampa Bay area with anywhere from 3in up to 1ft of rain ( highest where Pinellas/Hillsborough/Pasco meet).

[lando]

0z Drenched the Tampa Bay area with anywhere from 3in up to 1ft of rain ( highest where Pinellas/Hillsborough/Pasco meet).

Although the likely hood of this is so small given how far out and just one run, this would be catastrophic for the South Tampa area, which is extremely low lying and prone to flooding from just normal afternoon thunderstorms

[FixySLN]

Back to 90%

[imgur]https://i.imgur.com/vEEIM3t.png[/imgur]

[USTropics]

You'll see a trend started in yesterday's runs that are favoring the SW lobe a bit more:

GFS


ECMWF

[STRiZZY]

0z Drenched the Tampa Bay area with anywhere from 3in up to 1ft of rain ( highest where Pinellas/Hillsborough/Pasco meet).

Although the likely hood of this is so small given how far out and just one run, this would be catastrophic for the South Tampa area, which is extremely low lying and prone to flooding from just normal afternoon thunderstorms

Not to mention Pasco is super susceptible to river flooding.

[SouthFLTropics]

Well I wake up this morning to some
very interesting overnight model runs. I’m very much looking forward to these upcoming 06z runs to see if the strengthening and track trend from 00z continues. If the SW lobe of 92L forms, and IF it doesn’t get too tangled up in the big islands, it could pose a big problem this coming weekend. Regardless of development, PR, the LA and GA need to be ready for some substantial weather coming their way over the next few days.


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[STRiZZY]

92l roughly in the same spot/strength on the GFS 6z as the 0z through 72hrs.

6z


0z

[SouthFLTropics]

The 06z GFS brings the track further west once again, almost to the Florida coastline. While it continues to show a significant weakening trend in the Bahamas, I would take the intensity forecasts with a boulder sized grain of salt at this time.

[STRiZZY]

GFS 156hr weak mess into Palm Beach/Martin county

[jlauderdal]

The 06z GFS brings the track further west once again, almost to the Florida coastline. While it continues to show a significant weakening trend in the Bahamas, I would take the intensity forecasts with a boulder sized grain of salt at this time.

weakinging in the virgin waters of the Bahamas seems odd, gfs once again underestimating ridges? A southerly route through the straits seems as likely as anything else...euro has liked the southerly idea all along

[northjaxpro]

The 06z GFS brings the track further west once again, almost to the Florida coastline. While it continues to show a significant weakening trend in the Bahamas, I would take the intensity forecasts with a boulder sized grain of salt at this time.

I agree SFTropics. Yeah the sea surface temps are boling all over the Greater Antilles area, and around the Bahamas and off the Florida East and Gulf Coasts. Also, I am afraid that that some of the models, like the 06Z GFS this morning, just may be underdoing the intensity of this system this weekend . The main takeaway I am seeing is that the GFS is caving to the EURO, showing more ridging and moving this system through the Bahanas and approaching the Florida East Coast this weekend.

[USTropics]

Something I've noticed over the past 2 days of runs, the low-level axis has been tilted NE to SW currently, and we're left with two areas where air flow becomes divergent (or a NE lobe and a SW lobe attached to the wave axis).

https://i.imgur.com/iZqTmcc.png

https://i.imgur.com/9NZ8jHc.png

In the short term, we'll have to see if the SW lobe of the wave becomes the dominant feature. You can see currently there's a bit of a boxing match going on at the low levels between these two lobes:

https://i.imgur.com/J5EQHez.gif

As the axis approaches the Caribbean, if one of the lobes does not become the dominant feature, you'll notice the axis (blue) becomes more N to S oriented (natural process as these tropical waves enter the Caribbean due to low-level flow). Low-level easterly flow is cutting straight through the eastern Caribbean (red) which reduces the chance of the southern lobe developing. This easterly flow is also on the northern axis of the wave, but due to the proximity to the upper-level trough, the wind direction change from lower to upper levels is favoring development on the northern side of the axis now.
https://i.imgur.com/SxeBCQ2.png


Once we establish genesis, intensity becomes important. Levi does a great job of explaining this on his video (https://www.tropicaltidbits.com/), but essentially you can see the trough axis (yellow gradient) directly to the NW:
https://i.imgur.com/xx9EDc6.png

Through diabatic outflow, a tropical system can actually impinge on this trough axis, and essentially move it out of the way (or in some cases, even create ideal upper-level outflow, as we saw with Dorian last year). Previous runs that showed a more developed system were essentially strengthening here due to the storm having a protective bubble and impressive outflow. If you remove those conditions, a weaker tropical system will be sheared by the trough axis (as some model solutions now show).

The 00z GFS-para forecast shows what a well-organized system with enhanced diabatic outflow can do:

[Nimbus]

The 06z GFS brings the track further west once again, almost to the Florida coastline. While it continues to show a significant weakening trend in the Bahamas, I would take the intensity forecasts with a boulder sized grain of salt at this time.

weakinging in the virgin waters of the Bahamas seems odd, gfs once again underestimating ridges? A southerly route through the straits seems as likely as anything else...euro has liked the southerly idea all along

Sunny78 said it won't go over cat 2 due to climo/dry conditions.
If it spins up early it probably won't go south through the straits.

The elongation in the circulation will probably continue for at least a few days.
So of course it still could track through the big islands of the Caribbean in later runs.
See where the models are at the end of the day.

[SouthFLTropics]

Shouldn’t the 06z HWRF and HMON have come out by now? Are they just randomly running those at certain times?


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[OuterBanker]

If you want some pure entertainment look at the 0z Navgem.
A monster coast hugger from Florida to Maine.
Pure fantasy, but entertainment for shure.

[Aric Dunn]

One thing to remember is that all this recurve talk is all dependent of that weak cut off low over the central US/ohio valley.

well that feature does not exist yet..

So we know the drill..

[gatorcane]

I am not likIng how this may get into the Bahamas and the more bullish models coming in. By the way, the GFS ensembles that do develop are in good agreement into the Bahamas but look how some are turning it west into South Florida now. Others try to recurve. That is a change from prior runs:

[AutoPenalti]

I am not likIng how this may get into the Bahamas and the more bullish models coming in. By the way, the GFS ensembles that do develop are in good agreement into the Bahamas but look how some are turning it west into South Florida now. Others try to recurve. That is a change from prior runs:

https://i.postimg.cc/N061Ht4C/gfs-ememb-lowlocs-watl-23.png

West turn at the end of the run implies that the shortwave that’s been trying to develop by the GFS seems to be non existent or too slow by the time it approaches the Bahamas...

[Shell Mound]

I am not likIng how this may get into the Bahamas and the more bullish models coming in. By the way, the GFS ensembles that do develop are in good agreement into the Bahamas but look how some are turning it west into South Florida now. Others try to recurve. That is a change from prior runs:

https://i.postimg.cc/N061Ht4C/gfs-ememb-lowlocs-watl-23.png

West turn at the end of the run implies that the shortwave that’s been trying to develop by the GFS seems to be non existent or too slow by the time it approaches the Bahamas...

Note, however, that the most intense (rightward) members show a NW turn near the northern Bahamas, implying a track toward either GA or the Carolinas.

The biggest trend on both the G(E)FS and EC/EPS runs, however, has been favouring a slower, deeper shortwave trough over time, with ridging near FL.