Major Hurricane Grace

[Prismshine Productions]

The intense blowup of convection over the center quickly knocked the pressure down several mb first thing this morning, but the core convection has waned since then and the pressure has plateaued.  The overall organization continues to improve, though.  At some point today or tonight we should see more intense convection fire over the center again.

I say closer to Dirunal Max, we know with weak canes/strong TS how daytime heating raises the cloud temps...

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[NorthHillsWx]

Grace looks a little “popcorn-like” at the moment. Evidence of some of that mid level dry air.

[Prismshine Productions]

Recon is still out there?!

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[Prismshine Productions]

995.7, 16kt surface wind in the eye

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[hlcater]

Looks like grace took a bite of dry air over the last few hours. 

[cptcatz]

Is that an eye I see right next to the new hot tower popping up?

[Windspeed]

Waiting on convection to pop on the SW side of the circulation. The VDMs have showed robust instability but so far it's been lacking coverage. Any delay this evening will be good for the Yucatán as that limits time for rapid intensification to kick in but of course this could change in short order.

[NorthHillsWx]

14 minutes ago, Windspeed said:

Waiting on convection to pop on the SW side of the circulation. The VDMs have showed robust instability but so far it's been lacking coverage. Any delay this evening will be good for the Yucatán as that limits time for rapid intensification to kick in but of course this could change in short order.

Grace *still* lacks a coherent and robust core. Very fickle looking at the moment. Those westerlies on the south side of the circulation leave much to be desired. 

[Amped]

Finally convection over the center. Almost exactly 12 hrs from landfall.  Could be some impressive deepening in the next 12hrs though.

[hawkeye_wx]

1 hour ago, Amped said:

Finally convection over the center. Almost exactly 12 hrs from landfall.  Could be some impressive deepening in the next 12hrs though.

So far, today, every attempt to fire core convection has poofed out rather quickly.  Dry air appears to be a problem.

[hlcater]

30 minutes ago, hawkeye_wx said:

So far, today, every attempt to fire core convection has poofed out rather quickly.  Dry air appears to be a problem.

And indeed it is. Take a look at sondes 14-17.

[wxmx]

989mb extrapolated

[MJO812]

4 minutes ago, wxmx said:

989mb extrapolated

I'm seeing 995

Where are you seeing 989 ?

[Scott747]

5 minutes ago, MJO812 said:

I'm seeing 995

Where are you seeing 989 ?

Low-level Reconnaissance 

[jcwxguy]

6 minutes ago, MJO812 said:

I'm seeing 995

Where are you seeing 989 ?

 

[wxmx]

13 minutes ago, MJO812 said:

I'm seeing 995

Where are you seeing 989 ?

990mb from dropsonde and 10kts wind. Slowly but steadily intensifying.

[Amped]

990mb on the drop. Ernesto 2011 got down to 975mb in the hours before yucatan landfall. Grace doesn't look that organized though.

[wxmx]

Three hours old, but that's a pretty good structure. If it can get steady < -70C cloud tops in the eyewall, it can RI.

[Windspeed]

A hectic day but a significant change in Grace since my last post. Grace not only has evolved a tight core, it has multiple CBs rotating around its eyewall. This is a visual sign that intensification is ramping up. Anxious to see new recon data. Grace being slow to evolve structurally today is going to be a blessing for the communities and resorts along the Riveria Maya. It may still begin a period of significant intensification prior to landfall.

[Windspeed]

Sheesh, tired and totally looked at an older timestamp recon flight. At any rate, recon is in there right now:

[Dunkman]

Anyone have a link to the Cancun radar that’s not the crappy accuweather (or equivalent) version? Thanks.

[Windspeed]

Perhaps 5-6 hours at most from landfall. Another convective burst right over the center. Previous ones have relented including several healthy looking CDO features at times today. RI just isn't on the menu for the NW Caribbean this time. Some continued slow strengthening into landfall perhaps. The Cat 2 lock call I made this morning isn't looking so good. Probably going to end up a bust on my part unless.... Nope. Good night.

[Chinook]

Radar from Belize (maybe?)

[yoda]

Making landfall at 80mph... and might be one of those rare (I think?  Someone correctvme if I'm wrong) TCs to become a new storm in the Pacific basin

 

Hurricane Grace Discussion Number  24
NWS National Hurricane Center Miami FL       AL072021
400 AM CDT Thu Aug 19 2021

After a brief convective hiatus between 0400-0700 UTC, deep 
convection in the inner-core region has increased and become better 
organized during the past couple of hours. An Air Force Reserve 
Hurricane Hunter aircraft investigating Grace more than 4 hours ago 
reported a central pressure of 986 mb -- down 2 mb from previous 
passes -- and a maximum 700-mb flight-level wind speed of 74 kt on 
its last leg northbound around 0500 UTC. The 74-kt flight-level wind 
equates to about a 67-kt surface wind speed. These data supported 
maintaining a 70-kt intensity at 0600 UTC. The upper-level outflow 
remains symmetrical and has been expanding somewhat over the past 
few hours.

The initial motion is 280/15 kt based on the earlier recon fixes and 
passive microwave satellite data. Grace should continue to move 
generally westward for the next 48 hours, crossing the coast of the 
eastern Yucatan Peninsula within the next couple of hours, followed 
by a track across the Yucatan and emergence over the Bay of Campeche 
by 24 hours, with a subsequent landfall along the eastern coast of 
mainland Mexico shortly after the 48-hour forecast period. This 
track scenario is consistent with the latest 0000 UTC global and 
regional models, which show the strong deep-layer ridge to the north 
of Grace maintaining its expansive presence across the western 
Atlantic, Gulf of Mexico, and northern Mexico. After the second 
landfall, Grace is expected to turn west-southwestward and 
dissipate over the mountains of central Mexico by 72 hours. The new 
NHC forecast track is similar to the previous advisory track, and 
lies along the northern edge of the tightly packed consensus track 
models.

Given the recent improvement in Grace's inner-core convective 
structure noted in high-resolution infrared satellite imagery, some 
slight strengthening to 75 kt could still occur just prior to 
landfall this morning. Weakening will commence once Grace moves 
inland over Yucatan, with re-strengthening expected after the 
cyclone emerges over the Bay of Campeche where the vertical wind 
shear is forecast to decrease below 10 kt. Grace is expected to be a 
hurricane when the second landfall occurs along the coast of 
mainland Mexico, with the cyclone possibly reaching a peak 
intensity of 75 kt shortly after the 48-hour period. After final 
landfall in mainland Mexico, Grace should quickly weaken and 
dissipate over the mountains of Mexico by 72 hours, if not sooner.  
The remnants of Grace are expected to emerge over the eastern North 
Pacific and possibly re-develop there, but the uncertainty of 
whether this will be the original center or a new center precludes 
forecast points over the Pacific at this time.

A Hurricane Warning will likely be required for portions of the 
Hurricane Watch area of mainland Mexico later this morning or 
afternoon.

Key Messages:

1. Hurricane conditions and a dangerous storm surge are expected
in portions of the Hurricane Warning area in the eastern Yucatan
Peninsula of Mexico during the next several hours. Preparations to 
protect life and property should be rushed to completion.

2. There is an increasing risk of hurricane conditions and dangerous
storm surge in portions of eastern mainland Mexico beginning late
Friday, and a Hurricane Watch is in effect for part of this area.

3. Through the weekend, heavy rainfall across central and northern
portions of the Yucatan Peninsula and Veracruz State should lead to
flash and urban flooding. In addition, the heavy rainfall from Grace
will be capable of producing mudslides in Veracruz.


FORECAST POSITIONS AND MAX WINDS

INIT  19/0900Z 20.0N  87.2W   70 KT  80 MPH
 12H  19/1800Z 20.3N  89.7W   50 KT  60 MPH...INLAND
 24H  20/0600Z 20.6N  92.6W   60 KT  70 MPH...OVER WATER
 36H  20/1800Z 20.5N  95.0W   70 KT  80 MPH
 48H  21/0600Z 20.1N  97.3W   55 KT  65 MPH...INLAND
 60H  21/1800Z 19.7N 100.1W   20 KT  25 MPH...POST-TROP/INLAND
 72H  22/0600Z...DISSIPATED

$$
Forecaster Stewart

[NorthHillsWx]

Josh measured 978 in eye, considerably lower than NHC estimate at landfall 

[Chinook]

Hurricane Grace at 0828z, with the eye next to Cozumel and about to move into mainland Mexico

[NorthHillsWx]

2 hours ago, Chinook said:

Hurricane Grace at 0828z, with the eye next to Cozumel and about to move into mainland Mexico

If this had spent another 12 hours over water this morning it would’ve been a serious storm. Took really until the 11th hour to get its core put together 

[Prospero]

Sorry for not paying attention, having to do day job work catching up. Fred screwed up my schedule.

But did Grace ever get a real visible eye?? (I'd look now and then on sats.)

Will try to back track over posts later tonight...

[wxmx]

7 minutes ago, Prospero said:

Sorry for not paying attention, having to do day job work catching up. Fred screwed up my schedule.

But did Grace ever get a real visible eye?? (I'd look now and then on sats.)

Will try to back track over posts later tonight...

Briefly yesterday

Quote

A ragged eye appeared for a while on visible satellite imagery, but 
it has recently been obscured by cumulonimbus tops. 

https://www.nhc.noaa.gov/archive/2021/al07/al072021.discus.022.shtml?

[Prospero]

11 minutes ago, wxmx said:

Briefly yesterday

Best eyes of the year last year were the ones that pounded the Yucatan coast. Couple out in the Atlantic that we watched as well. But the ones that came in late season were very impressive and were devastating to that area.