Tropical Wave over the SE Bahamas (Is INVEST 91L)

[srainhoutx]

Saturday morning briefing from Jeff:

NHC has increased the chances for tropical cyclone formation over the next 5 days to 40%.

Tropical wave nearing the SE Bahamas this morning will be moving into the eastern Gulf of Mexico early next week where upper level winds are expected to become more favorable for tropical cyclone formation. Several global models now show the formation of at least a tropical storm along with many more of the ensemble members. The overall potential appears to be increasing that a tropical system will form in the Gulf of Mexico from the Tuesday-Thursday period and threaten the US Gulf coast. Since there is no defined surface low pressure system and it is uncertain where an actual center may form which will dictate the track. Building high pressure over the US east coast this week will likely force a WNW motion across the Gulf of Mexico and how fast and strong this high builds westward next week will determine if the system get trapped to the south of this feature or is able to get picked up by an upper level trough over the central plains. Conditions over the Gulf of Mexico look fairly favorable for development so it will need to be watched closely.

Will not make any changes to the local forecasts at this time since the uncertainty remains high…but a wet pattern will be developing today-Monday as a tropical wave south of the LA coast moves into the area. Rainfall amounts over the next 3 days may average 1-2 inches with isolated amounts of 3-5 inches.

Residents along the TX/LA coasts should monitor the progress of the tropical wave over the next 5 days…check forecasts at least once daily.

[SoupBone]

What a great morning.

So what's timing for Louisiana and Texas? Wednesday? We've seen this story play out far too many times. So we're seeing 30+ inches of rain on which models?

[jlauderdal]

in this case there's nothing to shred, if anything is concentrating the energy toward the turks/caicos.

sir, while there is no defined center it does appear hispaniola has caused a disruption, fracture, break, displacement or whatever you want to call it..we have seen hispaniola and eastern cuba do this many times to defined and ill defined systems.the upper levels weren't going to be conducive to development east of the conch republic, northern gulf and western gulf be ready

Disruptive, maybe, if anything was going. i think i understand what you are getting at though. it definitely scrambles it, although I think right around the inagua islands is where something is trying to happen at the moment (although that probably will shift because of those issues with Hispaniola/Cuba) It does slow it down.

disruption, yep

[srainhoutx]

What a great morning.

So what's timing for Louisiana and Texas? Wednesday? We've seen this story play out far too many times. So we're seeing 30+ inches of rain on which models?

WPC surface charts have the surface low just S of Vermillion Bay in Louisiana Wednesday morning and over Houston/Galveston Thursday morning at 12Z

[cycloneye]

Ramsdis floater.

[NDG]

Like some have mentioned the Operational Euro shows it becoming a hurricane as it makes landfall, and strengthening with wind gusts close to 100 mph over Nola and all around Lake Pontchartrain, good thing that it is only just a few ensemble members that agree with it.

[SoupBone]

Like some have mentioned the Operational Euro shows it becoming a hurricane as it makes landfall, and strengthening with wind gusts close to 100 mph over Nola and all around Lake Pontchartrain, good thing that it is only just a few ensemble members that agree with it.

Any link for the rainfall estimates? I seem to have misplaced that link since Harvey.

[Clearcloudz]

Like some have mentioned the Operational Euro shows it becoming a hurricane as it makes landfall, and strengthening with wind gusts close to 100 mph over Nola and all around Lake Pontchartrain, good thing that it is only just a few ensemble members that agree with it.

Any link for the rainfall estimates? I seem to have misplaced that link since Harvey.

https://weather.us/model-charts/euro/usa/acc-total-precipitation/20180911-0000z.html

[Clearcloudz]

HELLO ALL STATIONS
THIS IS THE FORECASTER DABUH WE NOW HAVE CENTER OF ROTATION AND LIKELY #GORDON COMING TO TAKE CENTER STAGE IN THE GULF OF MEXICO ALL RESIDENTS OF THE N-GULF FROM THE FL-PAN HANDLE TO TEXAS SHOULD CLOSELY MONITOR THE FORECAST


 https://twitter.com/DaDaBuh/status/1035887240902266880

[SoupBone]

Current shear over it right now. So can anyone explain in a "Dummie's Guide" kind of way, how shear can help with outflow and actually aid in development, rather than hinder? Is it based on location in relation to the wave?

[Clearcloudz]

The #tropical wave being monitored for development has reorganized.. Was initially amidst broad area of low-mid level spin, then became more focused, then dispersed (why models were inconsistent?), now has consolidated and is headed toward #Florida and the #GulfOfMexico ...

 https://twitter.com/StuOstro/status/1035890686938304513

[SoupBone]

The #tropical wave being monitored for development has reorganized.. Was initially amidst broad area of low-mid level spin, then became more focused, then dispersed (why models were inconsistent?), now has consolidated and is headed toward #Florida and the #GulfOfMexico ...

Not quite heading over the shredder, rather just north of it.

[BobHarlem]

More than a few places are picking up on this area as where it might get going.

@cfhc
The area being watched for development near the Bahamas is showing some signs of trying to organize, but nothing definite yet. Those in the Gulf should pay attention. Impacts for south Florida, (development or not) would just likely be a lot of rain on Monday.

 https://twitter.com/cfhc/status/1035893493493903361

[toad strangler]

Miami has mentioned the possibility of tornado activity with a system getting its act together. Being on the NE side of this it would be naive to just expect rain. We’ll see. FL is a footnote but in the crosshairs 1st.

[cycloneye]

Saved loop.

[NotSparta]

Current shear over it right now. So can anyone explain in a "Dummie's Guide" kind of way, how shear can help with outflow and actually aid in development, rather than hinder? Is it based on location in relation to the wave?

[img]http://i67.tinypic.com/9a67fa.gif[/ig]

Sometimes it's divergent shear, which causes more rising air, aiding convection. Usually this happens when a TC hooks up w/ the entrance region of an upper lvl jet, where the accelerating wind causes divergence there, which then causes rising air & convergence where the TC is, helping it, & also giving it a place to evacuate its outflow from the system, which also can strengthen it.

In this case, it would just be diverging wrt the wind vectors, but this amount of shear typically hinders development when it's right over the system

[NDG]

Current shear over it right now. So can anyone explain in a "Dummie's Guide" kind of way, how shear can help with outflow and actually aid in development, rather than hinder? Is it based on location in relation to the wave?

The UL trough ahead of it is creating diverging UL winds which in turn creates a rising motion which helps in a low pressure formation but at the same time the same shear keeps it from developing too fast until the UL trough moves out of the way or weakens and an UL ridge forms close to it which is what the Euro shows when it gets into the GOM.

[SoupBone]

Current shear over it right now. So can anyone explain in a "Dummie's Guide" kind of way, how shear can help with outflow and actually aid in development, rather than hinder? Is it based on location in relation to the wave?

The UL trough ahead of it is creating diverging UL winds which in turn creates a rising motion which helps in a low pressure formation but at the same time the same shear keeps it from developing too fast until the UL trough moves out of the way or weakens and an UL ridge forms close to it which is what the Euro shows when it gets into the GOM.

And that ULL is supposed to sweep southwest and move out of its way in the next two days. Gotcha.

[jlauderdal]

Mountains affect the flow, shredder works in several ways..long live the shredder..we have seen systems slow and even stall down there, bounce on and off the coast..shredder has major effects

The #tropical wave being monitored for development has reorganized.. Was initially amidst broad area of low-mid level spin, then became more focused, then dispersed (why models were inconsistent?), now has consolidated and is headed toward #Florida and the #GulfOfMexico ...

Not quite heading over the shredder, rather just north of it.

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[Hypercane_Kyle]

Hopefully this will be tagged as 91L sometime today.