ATL: LAURA - Post-Tropical - Discussion

[SouthernBreeze]

I haven't looked in a while. Laura covers so much area now. Huge even.

has grown considerably just since last NHC update!

[Chris90]

Another storm worth mentioning in regards to explosive intensification is Ike, when it was still out in the ATL. Went from 984mb to 935mb in 12 hours. Of course, that was based on satellite estimates, I don’t believe any recon had flown yet, but sometimes RI periods only last for 6-12 hours and it takes the storm to peak. I also think Dennis dropped 11mb in something like 60-90 minutes while in the Gulf. That wasn’t a steady 11mb/hr rate over a sustained period like 3-6 hours, it was just one very intense hour, but still very very impressive.

We may see Laura do something like this where she does all her heavy lifting in just 6-12 hours and it isn’t a steady fall from here until landfall.

[LarryWx]

What's the strongest US landfalling hurricane ever? I think Laura has a shot at that record..

Not at all; let's not hypecast. The Labor Day Hurricane had a central pressure of 892mb and maximum sustained winds officially but conservatively estimated at 185mph by the HURDAT reanalysis project (but likely in excess of 200mph, like Patricia) at landfall in the Florida Keys. The SSTs ahead (Maximum Potential Intensity) and the atmospheric conditions do not physically allow Laura to attain this intensity before landfall.

Yea, nothing even remotely close to that looks to happen. But it doesn't have to get even remotely close to that to be an extremely dangerous monster, which it just about is already with it bordering on major. I'm still at 951 for the lowest pressure out in the Gulf and 956 on landfall. Besides damaging/dangerous winds, these pressures would support solid major strength winds and devastating storm surge near and to the right of the eye. And if I'm not strong enough...well I don't want to think about that.

[Highteeld]

Eyewall still slightly open

[cfisher]

What's the strongest US landfalling hurricane ever? I think Laura has a shot at that record..

Not at all; let's not hypecast. The Labor Day Hurricane had a central pressure of 892mb and maximum sustained winds officially but conservatively estimated at 185mph by the HURDAT reanalysis project (but likely in excess of 200mph, like Patricia) at landfall in the Florida Keys. The SSTs ahead (Maximum Potential Intensity) and the atmospheric conditions do not physically allow Laura to attain this intensity before landfall.

Yea, nothing even remotely close to that looks to happen. But it doesn't have to get even remotely close to that to be an extremely dangerous monster, which it just about is already with it bordering on major. I'm still at 951 for the lowest pressure out in the Gulf and 956 on landfall. Besides damaging/dangerous winds, these pressures would support solid major strength winds and devastating storm surge near and to the right of the eye. And if I'm not strong enough...well I don't want to think about that.

dude it's probably already at 951, if not lower

[Blinhart]

I have a feeling the cone will shift west in the next advisory.

Why would you say that, all the models are in line with the cone, if not a little East?

[Highteeld]

Starting to bomb

[Blinhart]

Not at all; let's not hypecast. The Labor Day Hurricane had a central pressure of 892mb and maximum sustained winds officially but conservatively estimated at 185mph by the HURDAT reanalysis project (but likely in excess of 200mph, like Patricia) at landfall in the Florida Keys. The SSTs ahead (Maximum Potential Intensity) and the atmospheric conditions do not physically allow Laura to attain this intensity before landfall.

Yea, nothing even remotely close to that looks to happen. But it doesn't have to get even remotely close to that to be an extremely dangerous monster, which it just about is already with it bordering on major. I'm still at 951 for the lowest pressure out in the Gulf and 956 on landfall. Besides damaging/dangerous winds, these pressures would support solid major strength winds and devastating storm surge near and to the right of the eye. And if I'm not strong enough...well I don't want to think about that.

dude it's probably already at 951, if not lower

I don't know if it is that low right now, but I do believe it could make it down to close to 905 before landfall.

[Blinhart]

Starting to bomb

https://i.imgur.com/lMQwG7T.png

And we are getting the Pinhole Eye that is not a good sign, this thing has an excellent chance of Explosive Rapid Intensification.

[Blinhart]

well it's 8 minutes to 4am and nothing yet, they must be trying to figure out all the wording and how high of the level they will go with in this advisory.

[USTropics]

Starting to bomb

https://i.imgur.com/lMQwG7T.png

And we are getting the Pinhole Eye that is not a good sign, this thing has an excellent chance of Explosive Rapid Intensification.

A good bit of the eye is still obscured by convective debris, it's likely quite large (~50% more) than what we're seeing on satellite currently. Some retracting will take place as this closes off and tightens up.

[HurricaneEdouard]

Starting to bomb

https://i.imgur.com/lMQwG7T.png

And we are getting the Pinhole Eye that is not a good sign, this thing has an excellent chance of Explosive Rapid Intensification.

This is a medium-sized eye mostly covered by convection; it's simply clearing its eye. While I agree rapid intensification is likely (although I doubt it will meet the criteria for explosive deepening), this is not a pinhole eye. HWRF (which has been nailing the short-term structure and infrared satellite presentation of Laura since its formation) is forecasting a fairly large eye, as well.

[Buck]

...LAURA EXPECTED TO RAPIDLY STRENGTHEN TO A CATEGORY 4 HURRICANE... ...FORECAST TO PRODUCE A LIFE-THREATENING STORM SURGE, EXTREME WINDS, AND FLASH FLOODING OVER EASTERN TEXAS AND LOUISIANA LATER TODAY...
4:00 AM CDT Wed Aug 26
Location: 26.1°N 90.7°W
Moving: NW at 15 mph
Min pressure: 973 mb
Max sustained: 110 mph

[Blinhart]

Starting to bomb

https://i.imgur.com/lMQwG7T.png

And we are getting the Pinhole Eye that is not a good sign, this thing has an excellent chance of Explosive Rapid Intensification.

A good bit of the eye is still obscured by convective debris, it's likely quite large (~50% more) than what we're seeing on satellite currently. Some retracting will take place as this closes off and tightens up.

Anything under 25 miles wide eye is considered small, and that was when RECON was in there and it looks like it has gotten smaller since then, so I think this qualifies as a pinhole eye.

[Texashawk]

Wow. They are saying Laura is moving NW now. If that's northwest, then I'm typing German.

[KWT]

Starting to bomb

https://i.imgur.com/lMQwG7T.png

And we are getting the Pinhole Eye that is not a good sign, this thing has an excellent chance of Explosive Rapid Intensification.

This is a medium-sized eye mostly covered by convection; it's simply clearing its eye. While I agree rapid intensification is likely (although I doubt it will meet the criteria for explosive deepening), this is not a pinhole eye.

I agree, but it is looking good at the moment. Very chunky convection around the center now, with just that small opening still on the western side rotating around. At some point you've got to think thats going to close off.

Eye is slowly becoming more obvious though and each convective blow up is obscuring less and less of the eye each time.

[USTropics]

855
WTNT43 KNHC 260858
TCDAT3

Hurricane Laura Discussion Number 26
NWS National Hurricane Center Miami FL AL132020
400 AM CDT Wed Aug 26 2020

Satellite images indicate that Laura has become a formidable
hurricane since yesterday evening. Deep convection has intensified
and become more symmetric, with an eye now trying to clear out. An
earlier Air Force Hurricane Hunter mission found flight-level winds
of 104 kt, along with peak SFMR values of 86 kt, which supported the
90-kt intensity on the intermediate advisory. Since that time,
however, the cloud pattern has only continued to improve, so the
initial wind speed is set to 95 kt for this advisory. Notably, the
aircraft also recorded that the extent of the hurricane-force winds
have increased substantially northeast of the center. A pair of
Hurricane Hunter planes should be in the area within a couple of
hours.

The hurricane has intensified a remarkable 40 kt during the past 24
hours, and there are no signs it will stop soon, with shear
remaining low-to-moderate over the deep warm waters of the central
Gulf of Mexico. Guidance is noticeably higher than before, so the
new peak intensity will be raised to 115 kt, and some models are
even a little higher. Increasing shear is expected to slightly
weaken the hurricane close to landfall, so the new forecast keeps
the previous 105-kt intensity near the coast. Laura will
weaken rapidly after landfall, but it will likely bring
hurricane-force winds well inland over western Louisiana and
eastern Texas. In the extended range, there is some chance that
Laura re-intensifies as a tropical cyclone off the Mid-Atlantic
coast, instead of becoming part of a frontal system, but for now
the forecast will stay extratropical at 96 hours and beyond.

Recent satellite shows that Laura has turned northwestward, now
estimated at 13 kt. There are no substantial changes to the track
forecast to report. The hurricane should gradually turn toward the
northwest and north over the next day or two as it moves around the
western periphery of a mid-level high. The models are in very good
agreement on the center of Laura moving into extreme southwestern
Louisiana or southeastern Texas in about 24 hours, so no changes
were made to the previous NHC forecast. Later in the forecast period
the weakened cyclone should turn toward the east-northeast and move
with increasing forward speed while embedded within the mid-latitude
westerlies. The official track forecast is shifted southward at
longer range, not too far from the latest consensus track model
predictions.

It should be mentioned Laura is now a large hurricane, and wind,
storm surge, and rainfall hazards will extend far from the center.
Do not use the cone graphic for any representation of these hazards,
it is just for the center uncertainty.

[KWT]

...LAURA EXPECTED TO RAPIDLY STRENGTHEN TO A CATEGORY 4 HURRICANE... ...FORECAST TO PRODUCE A LIFE-THREATENING STORM SURGE, EXTREME WINDS, AND FLASH FLOODING OVER EASTERN TEXAS AND LOUISIANA LATER TODAY...
4:00 AM CDT Wed Aug 26
Location: 26.1°N 90.7°W
Moving: NW at 15 mph
Min pressure: 973 mb
Max sustained: 110 mph

Without recon being in there, that seems a fairly safe call, and if recon comes out with something deeper than that they can issue an advisory saying it is now a major.

Also quite telling they are now explicitly mentioning this becoming a category-4.

[Blinhart]

...LAURA EXPECTED TO RAPIDLY STRENGTHEN TO A CATEGORY 4 HURRICANE... ...FORECAST TO PRODUCE A LIFE-THREATENING STORM SURGE, EXTREME WINDS, AND FLASH FLOODING OVER EASTERN TEXAS AND LOUISIANA LATER TODAY...
4:00 AM CDT Wed Aug 26
Location: 26.1°N 90.7°W
Moving: NW at 15 mph
Min pressure: 973 mb
Max sustained: 110 mph

Yet they are still saying she will only get to 120, I don't know how they can be so conservative, especially with the way he worded it that there is no signs of this slowing down in strengthening.

[SouthernBreeze]

...LAURA EXPECTED TO RAPIDLY STRENGTHEN TO A CATEGORY 4 HURRICANE... ...FORECAST TO PRODUCE A LIFE-THREATENING STORM SURGE, EXTREME WINDS, AND FLASH FLOODING OVER EASTERN TEXAS AND LOUISIANA LATER TODAY...
4:00 AM CDT Wed Aug 26
Location: 26.1°N 90.7°W
Moving: NW at 15 mph
Min pressure: 973 mb
Max sustained: 110 mph

Yet they are still saying she will only get to 120, I don't know how they can be so conservative, especially with the way he worded it that there is no signs of this slowing down in strengthening.

130

FORECAST POSITIONS AND MAX WINDS

INIT 26/0900Z 26.1N 90.7W 95 KT 110 MPH
12H 26/1800Z 27.4N 92.4W 115 KT 130 MPH
24H 27/0600Z 29.7N 93.5W 105 KT 120 MPH...NEAR COAST
36H 27/1800Z 32.4N 93.7W 50 KT 60 MPH...INLAND
48H 28/0600Z 34.8N 92.9W 30 KT 35 MPH...INLAND
60H 28/1800Z 36.4N 91.0W 25 KT 30 MPH...INLAND
72H 29/0600Z 37.3N 87.3W 30 KT 35 MPH...INLAND
96H 30/0600Z 38.0N 74.5W 35 KT 40 MPH...POST-TROP/EXTRATROP
120H 31/0600Z 44.0N 60.0W 45 KT 50 MPH...POST-TROP/EXTRATROP