ATL: GAMMA - Post-Tropical - Discussion

[wxman57]

Wow, Gamma is impressive. Yet another victory for the HWRF — it got this exact structure right in yesterday’s 12z run.

Gamma’s incredibly deep CDO and much tighter pressure gradient suggests it would’ve been able to reach major hurricane intensity if it wasn’t about to run out of water.

Which run of the HWRF? Every single run has a different track and different max intensity. No consistency at all. It forecasts just about every disturbance to become a hurricane.

[aspen]

Wow, Gamma is impressive. Yet another victory for the HWRF — it got this exact structure right in yesterday’s 12z run.

Gamma’s incredibly deep CDO and much tighter pressure gradient suggests it would’ve been able to reach major hurricane intensity if it wasn’t about to run out of water.

Which run of the HWRF? Every single run has a different track and different max intensity. No consistency at all. It forecasts just about every disturbance to become a hurricane.

Yesterday’s 12z run. It showed a mid-980s system with a <-85C CDO close to making landfall. While the position is different (this was when the HWRF and GFS-Para were showing a change to NNW movement), the intensity and IR appearance were just about spot-on. I posted it in Gamma’s model thread.

[xironman]

55 kt, could be close to cane before it runs out of water.

[aspen]

55 kt, could be close to cane before it runs out of water.

At the rate it’s intensifying, I don’t doubt we’ll see Hurricane Gamma before landfall. It’s pressure dropped 4 mbar between passes (987 to 983) and FL winds have shot up to hurricane force.

[ElectricStorm]

55 kt, could be close to cane before it runs out of water.

At the rate it’s intensifying, I don’t doubt we’ll see Hurricane Gamma before landfall. It’s pressure dropped 4 mbar between passes (987 to 983) and FL winds have shot up to hurricane force.

983 mb is pretty low for a tropical storm anyway. Pretty sure this will become a hurricane before landfall, maybe at next advisory even

[aspen]

Down to 982 mbar extrap. Gamma could be in the mid 970s by landfall.

[wxman57]

Wow, Gamma is impressive. Yet another victory for the HWRF — it got this exact structure right in yesterday’s 12z run.

Gamma’s incredibly deep CDO and much tighter pressure gradient suggests it would’ve been able to reach major hurricane intensity if it wasn’t about to run out of water.

Which run of the HWRF? Every single run has a different track and different max intensity. No consistency at all. It forecasts just about every disturbance to become a hurricane.

Yesterday’s 12z run. It showed a mid-980s system with a <-85C CDO close to making landfall. While the position is different (this was when the HWRF and GFS-Para were showing a change to NNW movement), the intensity and IR appearance were just about spot-on. I posted it in Gamma’s model thread.

My point is, the HWRF has a completely different track and intensity solution every 6 hrs. To be considered successful/good, a model needs to be consistent with its forecasts, both track and intensity, or it cannot be trusted. I absolutely do not trust the HWRF for track or intensity. It consistently forecasts every disturbance to be a hurricane, and the tracks vary wildly from run to run. How can you say "this is a good run of the HWRF" when it is first issued?

12Z Yesterday


00Z Today

[Emmett_Brown]

Which run of the HWRF? Every single run has a different track and different max intensity. No consistency at all. It forecasts just about every disturbance to become a hurricane.

Yesterday’s 12z run. It showed a mid-980s system with a <-85C CDO close to making landfall. While the position is different (this was when the HWRF and GFS-Para were showing a change to NNW movement), the intensity and IR appearance were just about spot-on. I posted it in Gamma’s model thread.

My point is, the HWRF has a completely different track and intensity solution every 6 hrs. To be considered successful/good, a model needs to be consistent with its forecasts, both track and intensity, or it cannot be trusted. I absolutely do not trust the HWRF for track or intensity. It consistently forecasts every disturbance to be a hurricane, and the tracks vary wildly from run to run. How can you say "this is a good run of the HWRF" when it is first issued?

12Z Yesterday
http://wxman57.com/images/hwrf12z.JPG

00Z Today
http://wxman57.com/images/hwrf00z.JPG

Right, like the Euro, which up to 48 hours ago, very consistently showed an open wave for this morning.

[gfsperpendicular]

Yeah I think the only model that can really claim a victory on this is the GFS, and that's a little dubious given how it dropped it for a few days then picked it up again.

[wxman57]

Right, like the Euro, which up to 48 hours ago, very consistently showed an open wave for this morning.

Yes, there are extremes in the model runs. Global models often are too weak, HWRF is almost always too strong. By the way, the 6Z HWRF shifted to about 150 miles north of the 00Z run and showed steady weakening. At least the Euro has been more consistent run-to-run with the track forecast. GFS, too, for at least the first 5 days. I wouldn't trust the HWRF for a track forecast at all. The only time it seems helpful is when it doesn't indicate development at all. Otherwise, Cat 3+ every disturbance. It had Gamma as a Cat 3 in the central Gulf the night before last.

Here's the newest run of the HWRF. I think the track is likely way off, but the intensity forecast looks more realistic, given the dry air that will be entrained into the center later today.

[cp79]

Gamma having its fun now. In about 72 hours it’s gonna be fighting to survive (which I don’t think it will). Feel bad for the people in the Yucatán.

[cp79]

From what I’m seeing:

Euro, GFS Para, and CMC seem to kill Gamma in the BOC and form Delta on its wings and take it into the central/Eastern Gulf.

NAVGEM keeps Gamma around and does and full scale voyage of the northern gulf before settling around Tampa.

HWRF and HMON bury it in the BOC while the HWRF teases at Delta entering the Eastern Gulf.

[GCANE]

Latest Eye Drop

13.14Z
19.8N 87.2W

984mb, down from 987mb
92% RH at 700mb

[HurricaneEnzo]

Looks like HWRF nailed the short term intensity

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[us89]

I wish recon could have stayed for one more center pass. The two center dropsondes we did get gave a pressure change of -1.73 mb/hr.

Even if this is not operationally upgraded to a hurricane before it makes landfall on the Yucatan, I can see it being considered for that in post-analysis.

[Aric Dunn]

Looks like we have an eye beginning to try and clear out of both IR and visible.

[toad strangler]

Looks like we have an eye beginning to try and clear out of both IR and visible.

Looks like a healthy Cat 1 to me.

[NDG]

I've been dragging to get back into tropical discussion, this season has really put me behind at work, then my Mom was in ICU for two weeks with Covid.

It looks to me Gamma will be making landfall as a hurricane, too bad the recons left before it makes landfall in a few hours.

[northjaxpro]

Looks like we have an eye beginning to try and clear out of both IR and visible.

Yes we do have eye clearing out. Gamma is a hurricane for yours truly. I am a bit surprised NHC has not upgraded the system yet.

[ScottNAtlanta]

You can really see the contrast in air masses on both sides of Gamma. The puffy clouds on the left show really stable dry air