ATL: LAURA - Post-Tropical - Discussion

[Florida1118]

Let's say you have to make a 7-day track today, but you've "thrown out" all the models. What's the forecast?

The forecast is ... keep an eye on it.

Call it an open wave no matter what, and just post It’s Dead Jim

[SFLcane]

Let's say you have to make a 7-day track today, but you've "thrown out" all the models. What's the forecast?

A minimal TS nearing the Bahamas with a ridge over head with potential to strengthen. 06z Euro trended stronger with just that

[SouthFLTropics]

Let's say you have to make a 7-day track today, but you've "thrown out" all the models. What's the forecast?

A minimal TS nearing the Bahamas with a ridge over head with potential to strengthen. 06z Euro trended stronger with just that

You cheated...You brought a model into the discussion. He said you had to throw out all the models.

If I was to toss all the models and go with strictly my knowledge of past storms and climatology I would say a TS to a Cat 2 recurve through the Bahamas and clipping the Outer Banks.

[Blown Away]

8pm LAST NIGHT

8AM TODAY

As of 8am the NHC has really slowed down 98L in the 5 day window compared to 8pm last night, only makes it to @60W in 5 days... That makes me think the current modeling that shows 98L flying all the way to the EGOM in 7-8 days may not be what the NHC is thinking as of this morning...

[Aric Dunn]

Let's say you have to make a 7-day track today, but you've "thrown out" all the models. What's the forecast?

general wnw direction like the NHC.. the overall mass will move that way based off the current steering analysis.. dont need a model to tell me that. anything past 48 hours right now is less than a best guess

does not account for any potential up coming interactions between the two vorts. So any definitive forecast would be wrong on track and intensity.

so go ahead.. have at it.

[cycloneye]

 https://twitter.com/AndyHazelton/status/1295701889670172673

[gfsperpendicular]

https://i.imgur.com/mcKjWgp.jpg
8pm LAST NIGHT
https://i.imgur.com/GUAetWC.jpg
8AM TODAY

As of 8am the NHC has really slowed down 98L in the 5 day window compared to 8pm last night, only makes it to @60W in 5 days... That makes me think the current modeling that shows 98L flying all the way to the EGOM in 7-8 days may not be what the NHC is thinking as of this morning...

Probably just means they see it developing sooner. That's not a cone, it's an area for potential development.

[cycloneye]

12z Best Track:

AL, 98, 2020081812, , BEST, 0, 115N, 377W, 25, 1009, LO

At 1200 UTC, 18 August 2020, LOW INVEST 98 (AL98) was located in the North Atlantic basin at 11.5°N and 37.7°W. The current intensity was 25 kt and the center was moving at 15 kt at a bearing of 275 degrees. The minimum central pressure was 1009 mb.

[NDG]

I do think 98L will develop before reaching the Lesser Antilles but by no I way I believe any hurricane models forecasting it to become a hurricane before reaching the Islands. It is still mid August and there's still plenty of SAL, dust north of 98L that will be traveling westward along with it and will start affecting the system eventually, though not as dry as previous systems had to deal with, the reason why the latest 06z Euro and GFS don't do much with it before reaching the Lesser Antilles.
We may have to wait until late August/early September to see a strong hurricanes develop east of the Islands, like in 2017.
Another thing point out, a weaker system over the next 3-4 days, a more definite westward track most likely despite a strong Bermuda ridge already being forecasted to its north.

[SFLcane]

Might wanna head over the models thread and check out the increase in euro ensembles this morning.

[Aric Dunn]

12z Best Track:

AL, 98, 2020081812, , BEST, 0, 115N, 377W, 25, 1009, LO

At 1200 UTC, 18 August 2020, LOW INVEST 98 (AL98) was located in the North Atlantic basin at 11.5°N and 37.7°W. The current intensity was 25 kt and the center was moving at 15 kt at a bearing of 275 degrees. The minimum central pressure was 1009 mb.

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

I think there might be a slight problem with the location lol

[Shell Mound]

 https://twitter.com/pppapin/status/1295413537905483776



 https://twitter.com/AndyHazelton/status/1295706243756163075



As an aside, the feature to its east is already detaching itself from the ITCZ, so perhaps that area could become dominant over time, resulting in a slower speed. Perhaps a dominant centre may consolidate farther to the east and then 98L will be absorbed by prospective 99L. This could also affect the future evolution of the track, as a slower, deeper (stronger) system, being more vertically stacked, may also allow ridging to build beneath the trough over the Eastern Seaboard and result in a greater threat to South FL and the eastern Gulf of Mexico. Additionally, the following image, taken from this source, is interesting, given that 98L is juxtaposed with a probability maximum in mid to late August:

[msbee]

Good morning everyone
what are your thoughts on what effects thus will have on the northern Caribbean islands ?
I know its too early to tell but I would appreciate your thoughts. thanks

[sma10]

Between microscopic Gonzalo, gargantuan-sized Isaias wave, and now this two-headed monster, this has been the weirdest season in memory

[wxman57]

You can't put out a 7-day track forecast saying "a general WNW motion" (that's pretty obvious). A 7-day track requires precise lat/lon points, intensity, and wind radii. Throwing out all model guidance isn't a solution. The GFS/Euro and ensembles came into much better agreement with the 00Z run. They're both indicating building high pressure to its north as it passes the NE Caribbean Fri PM/Sat. That could drive the center right across the DR & Cuba Sun/Mon rather than allow a track toward/into the Bahamas. Such a track would keep it week, likely a depression if/when it reaches the Gulf early next week.

Another possibility is that the high to the north Fri/Sat is weaker, allowing a track north of the Greater Antilles and toward the Bahamas. This would allow for a much stronger storm system threatening Florida or the SE U.S. Coast north of Florida early next week. Maybe even a northward turn off the coast.

Unfortunately, I cannot put 2-3 different tracks on my forecast. Current consensus is across the Greater Antilles, so that's the best choice to start with.

[wxman57]

Good morning everyone
what are your thoughts on what effects thus will have on the northern Caribbean islands ?
I know its too early to tell but I would appreciate your thoughts. thanks

At the very least, some heavy rain and gusty wind Friday night and Saturday as it passes, quite possibly as a 40-50 mph TS. If it passes to your north then you won't get much wind.

[Aric Dunn]

You can't put out a 7-day track forecast saying "a general WNW motion" (that's pretty obvious). A 7-day track requires precise lat/lon points, intensity, and wind radii. Throwing out all model guidance isn't a solution. The GFS/Euro and ensembles came into much better agreement with the 00Z run. They're both indicating building high pressure to its north as it passes the NE Caribbean Fri PM/Sat. That could drive the center right across the DR & Cuba Sun/Mon rather than allow a track toward/into the Bahamas. Such a track would keep it week, likely a depression if/when it reaches the Gulf early next week.

Another possibility is that the high to the north Fri/Sat is weaker, allowing a track north of the Greater Antilles and toward the Bahamas. This would allow for a much stronger storm system threatening Florida or the SE U.S. Coast north of Florida early next week. Maybe even a northward turn off the coast.

Unfortunately, I cannot put 2-3 different tracks on my forecast. Current consensus is across the Greater Antilles, so that's the best choice to start with.

you just gave a right extreme and left extreme and went down the middle.. otherwise known as a "Cone of Uncertainty"

this, of course, is barring any major rotational interaction ( Fujiwara of sorts) between the two features for which models historically fail at every time and would potentially cause drastic shifts if the overall position of both features. So again until the two features fates are resolved and a single-center is established, anything other than a WNW motion for the next 48 hours is futile.

Also having precise lat/lon points inside the "cone" is not required. it is by convention only.

[Blown Away]

Definite broad circulation just N of 10N and W of of 38W

[NDG]

You can't put out a 7-day track forecast saying "a general WNW motion" (that's pretty obvious). A 7-day track requires precise lat/lon points, intensity, and wind radii. Throwing out all model guidance isn't a solution. The GFS/Euro and ensembles came into much better agreement with the 00Z run. They're both indicating building high pressure to its north as it passes the NE Caribbean Fri PM/Sat. That could drive the center right across the DR & Cuba Sun/Mon rather than allow a track toward/into the Bahamas. Such a track would keep it week, likely a depression if/when it reaches the Gulf early next week.

Another possibility is that the high to the north Fri/Sat is weaker, allowing a track north of the Greater Antilles and toward the Bahamas. This would allow for a much stronger storm system threatening Florida or the SE U.S. Coast north of Florida early next week. Maybe even a northward turn off the coast.

Unfortunately, I cannot put 2-3 different tracks on my forecast. Current consensus is across the Greater Antilles, so that's the best choice to start with.

Great post!

[Aric Dunn]

A rough outline from piecing together the ASCAT passes from a couple of hours ago.

Definitely some interaction between the two lobes. This will lead to some likely interesting short term motions.

So just sit back and enjoy the next 48 hours ..