ATL: GONZALO - Remnants - Discussion

[hohnywx]

And yet the NHC continues to forecast that Gonzalo will obtain hurricane status in less than 24hrs.

You guys are right, this storm has overachieved considering the suppressed Kelvin Wave. Just don’t know why the NHC hasn’t backed down significantly on intensity in its 11am forecast package. In my opinion chances this makes hurricane status are at 25% or less. If anything they seem to be playing catch-up.

Because the NHC does not just change their forecast on a whim. They value continuity and make gradual changes. As fast as the storm has become disorganized, it can reorganize. It's why they are the experts.

[USTropics]

Here is a big picture view of Gonzalo and the surrounding environment:


The relocation south was critical to Gonzalo surviving (green X). What we're currently seeing is the system again start to tap into some of that moisture associated with the ITCZ (highlighted in blue). The biggest detriment has been the leading stable air mass (yellow). In combination with the SAL plume to the north ( orange), this has strung out the convective complex to the NW (circled in red, likely the remnants of the UL circulation). Highlighted in red is the convective stream from this process. There are some signs in the last few frames Gonzalo is starting to draw some of this moisture back in (likely a result of the circulation strengthening). Convective banding on the east side with evident inflow channel is becoming established as well. It'll need to moisten the yellow shaded area up, but if it can do that we'll see another go at strengthening this evening.

[Kazmit]

And yet the NHC continues to forecast that Gonzalo will obtain hurricane status in less than 24hrs.

You guys are right, this storm has overachieved considering the suppressed Kelvin Wave. Just don’t know why the NHC hasn’t backed down significantly on intensity in its 11am forecast package. In my opinion chances this makes hurricane status are at 25% or less. If anything they seem to be playing catch-up.

Because the NHC does not just change their forecast on a whim. They value continuity and make gradual changes. As fast as the storm has become disorganized, it can reorganize. It's why they are the experts.

Exactly- these small storms can fluctuate in intensity quickly and frequently, so it doesn't make any sense for the NHC to adjust their forecast every time it does something they're not expecting.

[RT23]

GFS 12Z run has not back off on Gonzalo up to the Windwards.... maybe a little bullish on the intensity unless this hits RI later this afternoon into tonight...

[Do_For_Love]

Taking the "middle road" with the Gonzalo forecast and not overracting to the trends has proven to be a wise move IMO, it seemed yesterday that it was about to bomb out but that didn't occur. NHC is still stressing large uncertainty in the near term forecast so Gonzalo might not be totally done yet, although he's clearly struggling.

[typhoonty]

And yet the NHC continues to forecast that Gonzalo will obtain hurricane status in less than 24hrs.

You guys are right, this storm has overachieved considering the suppressed Kelvin Wave. Just don’t know why the NHC hasn’t backed down significantly on intensity in its 11am forecast package. In my opinion chances this makes hurricane status are at 25% or less. If anything they seem to be playing catch-up.

This right here is EXACTLY why the NHC are rightly seen as the end all be all. If some of the blog wrote the discussions there would be a 30 it change in peak intensity every advisory. The top post yesterday was "Here's your category 3! 2020!" and now, less than 24 hours later, people are acting as if the NHC should've
Issued the final advisory. Not changing your entire forecast due to a convection burst lends faith to the public.

I think most agree here, myself included, that they were too conservative yesterday morning, but they originally forecasted a 55 kt peak and its 55 it. Not sure why there are eye rolls or claims of underperformance.

[Mialco]

Here in Barbados we tend to mostly feel effects from storms that sneak up on us like Tomas haven’t really had any major impacts since then many Barbadians have a lackadaisical approach to hurricane preparedness, so far no one I have talked to has prepared as yet

Very true Weatherwatcher2018... I'm in Barbados also and have noticed the same. When I went to top up my supplies this week, people were looking at me like I was crazy. Watching this closely.

[abajan]

Here in Barbados we tend to mostly feel effects from storms that sneak up on us like Tomas haven’t really had any major impacts since then many Barbadians have a lackadaisical approach to hurricane preparedness, so far no one I have talked to has prepared as yet

True, but there were definitely more people in the supermarket (specifically, Massy Worthing) yesterday than normal.

[Ubuntwo]

Very tight circulation and very small storm. Considering the size and usual ASCAT undersampling, 55kt is justified.

[USTropics]

A more zoomed in view. Another key feature to watch is this boundary layer (highlighted in purple) pushing W/SW. This is a result of the convective complex finally collapsing to the NW, and some of that moisture is being drawn back into the system as well (green). In addition, some inflow channels and banding (blue) are becoming evident. This is tapping into the daytime convective moisture over South America and the moisture plume to the east.

[Nuno]

When was it the last time the MDR had a storm this small?

[SconnieCane]

When was it the last time the MDR had a storm this small?

Beryl 2018, most likely.

[storminabox]

Wow this storm really suffered overnight. Dry air really got the best of it. We’ll see if it can recover but it’s certainly a lot more vulnerable than we have seen it thus far:

[Visioen]

Thx USTropics, love the way you use those images and explain things.

[EquusStorm]

It's certainly still got a super vigorous core. Hurricane is certainly possible but I dunno how long it lasts at that intensity

[Fego]

A more zoomed in view. Another key feature to watch is this boundary layer (highlighted in purple) pushing W/SW. This is a result of the convective complex finally collapsing to the NW, and some of that moisture is being drawn back into the system as well (green). In addition, some inflow channels and banding (blue) are becoming evident. This is tapping into the daytime convective moisture over South America and the moisture plume to the east.

https://i.imgur.com/xOAS3mC.png

Great explanation USTropics. Could that boundary layer (purple) somewhat moist the area ahead of Gonzalo?..

[northjaxpro]

It is a very tiny storm. However it still has a coc with 55t Kt wind. So, yes these small cyclones can ramp up and down very quickly. I feel that if Gonzalo can stay at low latitude, it can fend off the SAL and bounce back, as soon as late this afternoon into this evening.

It woild be foolish for some of you to proclaim the dèmise of Gonzalo just yet. 2020 has been loaded with surprises thus far. Why should this stop now?

[BYG Jacob]

A more zoomed in view. Another key feature to watch is this boundary layer (highlighted in purple) pushing W/SW. This is a result of the convective complex finally collapsing to the NW, and some of that moisture is being drawn back into the system as well (green). In addition, some inflow channels and banding (blue) are becoming evident. This is tapping into the daytime convective moisture over South America and the moisture plume to the east.

https://i.imgur.com/xOAS3mC.png

He's not dead yet

[TallyTracker]

Just to preface, this is not what it’s going to do...

With that out of the way, remember Dorian was in a similar area last year and struggled for a while but bounced back. Gonzalo could recover and exceed the forecast.

My personal guess right now is that convection will pulse over the next couple of days due to dry air ingestion. Winds will remain largely steady up to the Windward Islands. Once in the eastern Caribbean, I suspect Gonzalo will weaken quickly due to a combo of increasing shear, dry air, and disruptive low-level flow off South America. It would not surprise me if Gonzalo opens up into a wave in the south central Caribbean. Beyond that in the Western Caribbean, regeneration/reintensification may be possible, but we are way to far out to make any kind of accurate predictions of what happens to Gonzalo beyond the central Caribbean.

[wx98]

Down to 60 mph, which is warranted given Gonzalo’s current state:

2:00 PM AST Thu Jul 23
Location: 9.7°N 48.8°W
Moving: W at 14 mph
Min pressure: 1000 mb
Max sustained: 60 mph