ATL: BARRY - Post-Tropical - Discussion

[galveston-d]

Thanks - my husband and I are moving from Galveston this Friday. Even if it comes this way, I bet we will be outta here before it comes. But I hope all my friends here on the coast take care!

Everyone in the path please keep safe. This could be the nightmare scenario many forecasters have always feared: a system forms that the models don't have a good handle on, it then goes from a nothing into a major hurricane so fast people don't have adequate time to evacuate at risk coastal areas. My fervent hope is this one doesn't bomb out in the GOM once it becomes established or better yet it doesn't become established in the first place. Let's all hope for the best.

[Dean4Storms]

We've had some strong to severe TStorms form along the Emerald Coast here in the Destin area this afternoon with very prolific lightning moving out over the Gulf. You can almost sense the charged atmosphere and that it is ripe for something to come of this Low once it gets offshore tomorrow.

[cycloneye]

There has been mentions about the 1943 surprise hurricane and Webb adds a little more insight.

 https://twitter.com/webberweather/status/1148371563206434817

[djones65]

I personally see many similarities to 1986 Hurricane Bonnie...
I remember tracking a well defined surface vorticity maximum which tracked the spine of the Florida Peninsula north to south...
Then it back tracked northwestward briefly over the NE Gulf of Mexico where it began developing in June 1986.
It ended up as an 80-85 mph category 1 hurricane.

I personally like '86 Bonnie as the best analog currently.

[p1nheadlarry]

Everyone in the path please keep safe. This could be the nightmare scenario many forecasters have always feared: a system forms that the models don't have a good handle on, it then goes from a nothing into a major hurricane so fast people don't have adequate time to evacuate at risk coastal areas. My fervent hope is this one doesn't bomb out in the GOM once it becomes established or better yet it doesn't become established in the first place. Let's all hope for the best.

Didn’t we just have a similar situation last year with Michael?

Yes, the models were all over the place for a long time with Michael as I recall. The difference here is this one could form and then deepen quicker.

Honestly I think they performed well. Track for sure. Intensity-wise there were several runs where everyone scoffed at how bullish they were. I have a few saved on my phone being in the line of fire, and they still under-estimated the intensity. One run I have saved is from October 6 and showed a 941 hPa hurricane hitting the Walton/Okaloosa line.

I think a good paper could be published by looking back at some of the models runs where the intensity of Michael were high compared to what the NHC forecast at the same time, investigate, and compare with what was observed. Lord knows there are dozens of potential case studies that could be done and are already being published.

[TheAustinMan]

Right now, the timeline for 92L looks something like this, based on the available model guidance:

Happening Now: Scattered thunderstorms across Georgia and Florida this evening due to the land-based diurnal maximum. Storms near Tallahassee will help pull the low-level vorticity towards the Gulf of Mexico, but they'll also wither away in a few hours. The 500hPa vorticity maximum is diving south through the Fort Walton Beach area and should be in the Gulf soon. The lower level circulations are still out near the FL/GA border, and the surface low is still broad and trying to sort itself out.

Early Tuesday Morning: Convection initiates in the northeastern Gulf, at least temporarily, with the aid of the ocean-based diurnal maximum. Guidance suggests the storms will probably take the form of a west-to-east line that accelerates southward. These cells will pull the circulation towards the Gulf, but by how much is the million dollar question. In the storms' wake, convection will probably die down a bit due to convective inhibition before increasing again in the evening.

Tuesday Afternoon: The low-level vorticity maximum (at 850hPa) begins to move into the Gulf of Mexico. Models disagree on the exact placement of this circulation, but there is general agreement that it will either be along the coast or over open waters of the northeastern Gulf of Mexico by the evening hours on Tuesday. The GFS still has it hung up near Tallahassee at this point - that's the biggest disagreement. Because of the convective inhibition caused by the storms in the morning, don't be surprised if this transition happens without much convective fanfare.

Wednesday Morning: A new surge in convection probably occurs with the diurnal maximum, this time further west but still in the eastern Gulf (probably about 150 miles south of Panama City, FL). By this time it should be relatively clear whether the storm is trending towards the (currently) north-GFS or south-ECMWF. If the low-level 850hPa center is near 30N, that's what the GFS has been showing. If it's near 28N, that's more akin to the ECMWF's depiction. Inevitably it will probably look like a mix between the two, as is tradition.

Wednesday Evening: This is about the soonest (and most optimistic) time that we're able to get a tropical depression, according to the models.

After that... Models are in bigger disagreement over the details out here. If you like the models that make landfall around Mississippi or the Mississippi Delta region (weaker ridge, stronger trough solutions), those make landfall on the Mississippi Delta Friday evening (so about 3 days to ramp up). If you like the models that make landfall around Houston/Lake Charles (stronger ridge, weaker trough solutions), those move inland around Saturday into Sunday. (or about 4 days to ramp up) Until then, how much the storm strengthens is dependent on whether the circulations aloft and at the surface can align themselves. We start to get an indication of that Wednesday.

Regardless of whether we get a storm at all or whether a hurricane occurs, widespread rainfall is expected throughout the northern Gulf coast. Probably widespread 1-3" along the immediate coast with isolated areas above 4" even if nothing organizes. The WPC has a 5-day QPF total of 2.5" stretching along the coast from Galveston to Naples, and they've posted a Day 3 Marginal Risk for excessive rainfall along Florida's Nature Coast. Certainly a high risk of rip currents along the coast and rough seas offshore as with any Gulf low pressure system. Of course, a stronger storm magnifies all risks near the center of circulation.

[cycloneye]

Great rundown.

[jasons2k]

I'm quietly getting prepared up here. Not taking any chances. The Gulf has a history of unpredictable and rapidly intensifying storms.

[sphelps8681]

I'm quietly getting prepared up here. Not taking any chances. The Gulf has a history of unpredictable and rapidly intensifying storms.

Me too. Cleaned out frig and going tomorrow to stock up just in case.

[cycloneye]

00z Best Track:

Location: 32.1°N 83.3°W
Maximum Winds: 15 kt Gusts: nan kt
Minimum Central Pressure: 1010 mb
Environmental Pressure: 1012 mb
Radius of Circulation: 150 NM
Radius of Maximum Wind: 80 NM

[Steve]

I'm quietly getting prepared up here. Not taking any chances. The Gulf has a history of unpredictable and rapidly intensifying storms.

I think I’m going to get a jump on some provisions tomorrow. I don’t expect that bad here, but you gotta be ready for street flooding and power outages anyway. Looks like whatever happens, 92L will probably keep moving after landfall. EC has high pressure up north after landfall so maybe no long lasting effects and a system that moves out ENE-E if there’s a block. Still, all the folks in Arkansas and the Tennessee Valley probably should pay attention as well in case the remnants take a more southern track to the Atlantic.

Edit to say ECMWF at 12, it’s more of a West and Northwest Block building and a way out through Oklahoma, Missouri and toward the Ohio Valley. So don’t sleep farther north and west either if you’re in post landfall range

[psyclone]

Just to illustrate how things can change...the current QPF bullseye from the folks at the WPC is now the upper texas/southwest Louisiana coast and as recently as a few forecast cycles ago they were completely out of the fray. This underscores the vital importance of staying in touch as projections evolve. Even if you're not in the hot zone now in 72 hours it might be a different story..


https://www.wpc.ncep.noaa.gov/qpf/p168i.gif?1562634220

[Nimbus]

We've had some strong to severe TStorms form along the Emerald Coast here in the Destin area this afternoon with very prolific lightning moving out over the Gulf. You can almost sense the charged atmosphere and that it is ripe for something to come of this Low once it gets offshore tomorrow.

Pensacola just received a big storm from the lift blowing east on the south side of the front.
Mobile bay should be next and that is about as far as whats left of the front extends west.
If persistent convection forms south of there we can check the buoys in the morning for surface pressures and wind directions.

Edit to add: the surface pressure reached 1011 last hour in Mobile bay which is only 1 millibar above the lowest recorded surface pressure. As Levi explained this morning that could change with persistent convection..

[sphelps8681]

My local met said we could see 10-20 inches of rain if it comes our way.

[cycloneye]

Great discussion thread from Philippe Papin.

 https://twitter.com/pppapin/status/1148396466643169280




 https://twitter.com/pppapin/status/1148396471797968896




 https://twitter.com/pppapin/status/1148401798954115072




 https://twitter.com/pppapin/status/1148403772147691520

[kn4ds]

00z Best Track:

Location: 32.1°N 83.3°W
Maximum Winds: 15 kt Gusts: nan kt
Minimum Central Pressure: 1010 mb
Environmental Pressure: 1012 mb
Radius of Circulation: 150 NM
Radius of Maximum Wind: 80 NM

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

I wonder if that location isn't a bit off... pressures have been rising the last few hours here in middle Georgia. I think the center is further south, closer to Valdosta.

[tropicwatch]

00z Best Track:

Location: 32.1°N 83.3°W
Maximum Winds: 15 kt Gusts: nan kt
Minimum Central Pressure: 1010 mb
Environmental Pressure: 1012 mb
Radius of Circulation: 150 NM
Radius of Maximum Wind: 80 NM

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

I wonder if that location isn't a bit off... pressures have been rising the last few hours here in middle Georgia. I think the center is further south, closer to Valdosta.

That location is three hours old. It is making its way into Florida and looks like it will enter the gulf east of Panama City.

[cycloneye]

 https://twitter.com/iCyclone/status/1148445382382194688

[Aric Dunn]

Circ/vorticity is nearing the coast around the big bend area as convection begins to build well offshore. Going to be an interesting day. Watching this evolve.

[LeonardRay]

Circ/vorticity is nearing the coast around the big bend area as convection begins to build well offshore. Going to be an interesting day. Watching this evolve.

Some really big storms popping up in the gulf, I cant see the vorticity, where do you have it pinned?