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Tropical 2025 Tropical Thread

This year's hurricane season has been frustrating and hard to predict for forecasters and casual weather watchers. The latest disturbance that is being watched is typical for an untypical season like the one we are having. If that system stalls out over Hispaniola as the models are suggesting it will be ripped to shreds by the mountainous terrain and will pose no threat anywhere else as a tropical system.
 
The 0Z UKMET once again has just a rather weak low (not even a TC on the textual output; it has yet to show TCG in the Caribbean on this output though it awhile back had several runs with TCG east of the Lesser Antilles) and again into Nicaragua. The last 5 runs have shown a weak low either hitting Nicaragua (0Z 10/19, 12Z 10/18), barely E of Nic. but heading into it (0Z 10/18, 12Z 10/17), or still 200 miles E of Nic. but likely headed into it (0Z 10/17).

Looking at the H5 vorticity, it appears that as the AOI on the TWO comes into the E Car that a portion of it turns sharply right like the GFS but unlike that model it never develops. Then what looks like a split from this, possibly incorporating additional vorticity coming off northern S America, causes the weak low to move into the SW Caribbean, which then goes into Nicaragua.

So, the UKMET remains a SW outlier. I should add that yesterday’s 12Z JMA is similar and it has been similar all of the way back to the 12Z 10/15 run. So, the JMA has had 4 12Z runs in a row with just a weak low into Nicaragua or just offshore headed there.

Thus the UKMET and JMA have a good chance to both either fail badly or end up doing the best of the major operationals with this.

0Z 10/19 UKMET 156:
IMG_4902.png

12Z 10/18 JMA 168:
IMG_4901.png
 
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Of course, I always look for a prominent "starter" event like a deep trough or combination with a western Atlantic Basin hurricane. There is good support for a major system affecting the Greater Antilles in the longer term, then accelerating north and possibly merging or phasing with a big cold trough complex close to the East Coast. It is very early in the game, but the waters are very warm and the cPk air mass will likely head toward Texas and Mexico before pushing through Dixie. If a gap is present, the big cyclonic circulation may track due north or possibly undergo a jog toward Virginia, the Mid-Atlantic or New England. For all of this to happen, we must see a strong Rex or Omega block in Nunavut AR. And should this cyclonic path occur, we can finally start to get rid of the "Indian Summer In Overdrive" pattern.





Prepared by Meteorologist LARRY COSGROVE​
 
GaWx said:
The 0Z UKMET once again has just a rather weak low (not even a TC on the textual output; it has yet to show TCG in the Caribbean on this output though it awhile back had several runs with TCG east of the Lesser Antilles) and again into Nicaragua. The last 5 runs have shown a weak low either hitting Nicaragua (0Z 10/19, 12Z 10/18), barely E of Nic. but heading into it (0Z 10/18, 12Z 10/17), or still 200 miles E of Nic. but likely headed into it (0Z 10/17).

Looking at the H5 vorticity, it appears that as the AOI on the TWO comes into the E Car that a portion of it turns sharply right like the GFS but unlike that model it never develops. Then what looks like a split from this, possibly incorporating additional vorticity coming off northern S America, causes the weak low to move into the SW Caribbean, which then goes into Nicaragua.

So, the UKMET remains a SW outlier. I should add that yesterday’s 12Z JMA is similar and it has been similar all of the way back to the 12Z 10/15 run. So, the JMA has had 4 12Z runs in a row with just a weak low into Nicaragua or just offshore headed there.

Thus the UKMET and JMA have a good chance to both either fail badly or end up doing the best of the major operationals with this.

0Z 10/19 UKMET 156:
View attachment 175572

12Z 10/18 JMA 168:
View attachment 175573
Click to expand...

Followup from yesterday:
-12Z UKMET was still another headed into Nicaragua with a weak low

-12Z JMA: after four 12z runs in a row of weak low into Nicaragua, yesterday’s was a bit stronger (1004-5 mb) and slightly further N with a Mitch-like track that skimmed the N coast of Honduras
 
There remains the 3rd main model option for 98L (other 2 options being either like GFS of sharp turn right or Euro/Icon slower development allowing it to get to W Car and develop there) that of many UKMET runs in a row (including today’s 0Z) that never get it much more organized than it is now due to a splitting off of the main H5 vorticity, which turns sharply north in the E Car leaving behind just a weak surface low. That weak low then continues westward in the S Caribbean with the run then ending (168) with just a 1007 low that’s likely about to dissipate near the Nicaragua coast underneath a pretty solid ridge.

The JMA had been similar though the latest run (yesterday’s 12Z that I just posted) developed it into a 1004-5 TD to possibly low end TS that skims the N coast of Honduras to S Belize at 192 (end).

Interestingly, the 0Z CMC was kind of similar to the 12Z JMA though it survives Honduras and then turns NE as a TS over WC Cuba and then the NW Bahamas.

We’ll see whether or not this is one of those cases of the UKMET being genesis shy/too weak due to the splitting of energy. It (along with the JMA for the most part) has a good chance to either bust badly or score a coup.
 
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