Tropical Wave in Bay of Campeche (Is Invest 91L)

[LarryWx]

0Z Euro: 999 mb TS landfalls in Belize at 240 moving W

[Blown Away]

0Z Euro: 999 mb TS landfalls in Belize at 240 moving W

Larry, the globals starting to back off significant development again with this disturbance and it stays weak and goes W…

[LarryWx]

0Z Euro: 999 mb TS landfalls in Belize at 240 moving W

Larry, the globals starting to back off significant development again with this disturbance and it stays weak and goes W…

Global ops other than ICON have been pretty inconsistent/unpredictable, which to me is when model watching is most interesting.

[Teban54]

The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the NHC and NWS.

I actually wonder if the (non-ICON) models are correctly picking up on the great uncertainties of the monsoon trough breakdown, and not just simply being inconsistent. It sounds like which one of the two lobes (west or east) becomes more dominant in low-level vorticity plays a significant role in how much the system consolidates before the Lesser Antilles, which has butterfly effects on genesis, intensity and track. Whether landfall is in Nova Scotia, Tampa, Mississippi, Belize or nowhere has everything to do with short-term evolution, and little to do with conditions down the road.

Unfortunately, if my hypothesis is true, we may have no way of knowing whether the system will actually form other than waiting for another 24-48 hours, possibly more.

There's also the possibility that how the system behaved in the last 24 hours was unexpected by models, and they're playing catchup leading up to a scenario that's less favorable for consolidation and development. But whether that's actually true is way outside my knowledge base.

[Stratton23]

Yikes, vast majority of the 00z EPS favors the gulf now, less up the se coast

[LarryWx]

Hopefully Adrian is sleeping because the 0Z Euro ensemble is still pretty active around FL. The operational is a clear S outlier. The ensemble mean didn’t slip S much if at all.

[skyline385]

0z EPS still decently active and most of the US Gulf coast seems to be within the spread.

[aspen]

No development on the 06z GFS so far.

[USTropics]

The posts in this forum are NOT official forecasts and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the NHC and NWS.

I actually wonder if the (non-ICON) models are correctly picking up on the great uncertainties of the monsoon trough breakdown, and not just simply being inconsistent. It sounds like which one of the two lobes (west or east) becomes more dominant in low-level vorticity plays a significant role in how much the system consolidates before the Lesser Antilles, which has butterfly effects on genesis, intensity and track. Whether landfall is in Nova Scotia, Tampa, Mississippi, Belize or nowhere has everything to do with short-term evolution, and little to do with conditions down the road.

Unfortunately, if my hypothesis is true, we may have no way of knowing whether the system will actually form other than waiting for another 24-48 hours, possibly more.

There's also the possibility that how the system behaved in the last 24 hours was unexpected by models, and they're playing catchup leading up to a scenario that's less favorable for consolidation and development. But whether that's actually true is way outside my knowledge base.

Really good points and highlights the complexities that global models often face when dealing with smaller-scale phenomena, such as the interplay between vorticity lobes—a process inherently tied to mesoscale dynamics. I'll add to this that we have two lobes that extend all the way to the mid-levels (~700mb) and it'll be interesting to see how this evolution plays out today. From CIMSS products, it looks like we're setting up for a pivot (I've outlined this below):


Three plausible scenarios emerge from this setup: (1) the eastern lobe (pink) continues to dominate and intensifies during its downward ascent; (2) the western lobe (orange) shifts upstream, encounters more favorable conditions, and amplifies; or (3) a consolidation occurs between the two lobes. The difficulty in modeling this process is evident in the last six GFS runs, which struggle to capture these nuances (a limitation expected given the resolution constraints of global models):


This underscores the critical role that ensemble forecasting plays over single deterministic models, particularly in situations lacking a clear center of circulation. Another frame of mind to think of this is a hypothesis test/experiment, where our deterministic global model run is a singular outcome from an experiment. We know that the limited surface data over oceans and the inherent difficulty global models face in resolving mesoscale features can result in compounded errors over time. Recognizing that our model forecasts are sensitive to initial conditions, relying on a single run—even with the highest resolution—may not yield the most reliable outcome. Instead, examining a range of possible outcomes through ensemble runs, where each run varies slightly in its initial parameters, provides a more robust framework for understanding potential scenarios.

This brings us to the concept of standard deviation, which is crucial in ensemble forecasting. A large deviation from the mean, or spread, indicates a high level of uncertainty in the forecast track. The 00z ECMWF ensemble runs, for example, show a significant spread of outcomes, as depicted below:

[MEANINGLESS_NUMBERS]

GEPS August 30 00z only one or two of the ensembles develop. Mostly the wave fails the launch.

[abajan]

No development on the 06z GFS so far.

It eventually starts to consolidate around a week from now (Hour 162), just south of Jamaica.

[WaveBreaking]

06z gfs has a strengthening TS entering the Gulf over the Yucatan @246 hours.

[N2FSU]

06z GFS




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[chris_fit]

GFS last 6 model trend for Monday Sep 9th.... All over the place with track and intensity.

[N2FSU]

06z GFS




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[SFLcane]

The chances this never gets out of the Caribbean look about fair right now. Feeling a little better for Florida today the longer this take to develop it will just ride straight into the Yucatan which obviously could brings impacts to that region depending how strong it gets. Would also not surprise if this never gets going which of course will be good for everyone.

[SouthFLTropics]

06z GEFS Ensembles are mostly north of the big islands and well east of the SE US coast, save for a few in the GOM. Models are all over the place with this one.

[LarryWx]

The chances this never gets out of the Caribbean look about fair right now. Feeling a little better for Florida today the longer this take to develop it will just ride straight into the Yucatan which obviously could brings impacts to that region depending how strong it gets. Would also not surprise if this never gets going which of course will be good for everyone.

Hope FL isn’t hit. But did you see the 0Z EPS tracks?

[MarioProtVI]

Down to 0/40 but shifted development area west.

[BobHarlem]

Wow the ensembles go from Central America to east of Bermuda although the Euro ones are all on the west side in the Gulf or left of the Bahamas. Is it really early September here?