GaWx

TROPICAL DEPRESSION FIONA ANALYSED POSITION : 16.4N 51.4W ATCF IDENTIFIER : AL072022 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 15.09.2022 0 16.4N 51.4W 1010 36 1200UTC 15.09.2022 12 16.4N 53.9W 1009 38 0000UTC 16.09.2022 24 16.7N 56.2W 1008 37 1200UTC 16.09.2022 36 17.0N 58.9W 1009 35 0000UTC 17.09.2022 48 17.5N 61.6W 1008 30 1200UTC 17.09.2022 60 17.8N 64.0W 1007 31 0000UTC 18.09.2022 72 18.0N 66.5W 1006 32 1200UTC 18.09.2022 84 18.6N 67.8W 1004 39 0000UTC 19.09.2022 96 18.8N 68.6W 1002 43 1200UTC 19.09.2022 108 19.8N 69.9W 996 53 0000UTC 20.09.2022 120 20.5N 71.2W 995 53 1200UTC 20.09.2022 132 21.1N 72.0W 996 51 0000UTC 21.09.2022 144 22.0N 72.2W 997 45

Followup: - The 12Z ICON makes this a H near 14N, 50W, and then takes it NW. - The 12Z JMA takes this westward to just E of LAs as a very weak low moving WNW at 192 hours. - The 12Z Euro is the 4th in a row that has a persistent surface low from the AEW just now leaving Africa. The prior three all hit the Lesser Antilles. This run has it just E of the LAs as of 168 moving W (Sept 21st) after which it moves W well into the Caribbean as a very weak low: Update for 12Z EPS: Those members at 240 which are located from NE of PR to the LAs to the MHs NE of the Leewards as well as those members S of PR and Hisp. in the Caribbean are from this AEW that's now just off Africa rather than from 96L. Some of those Caribbean members then go into the Gulf. Update: The 12Z UKMET has this: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 138 HOURS FORECAST POSITION AT T+138 : 12.9N 48.2W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 20.09.2022 144 13.2N 49.2W 1009 30

12Z UKMET TROPICAL DEPRESSION 96L ANALYSED POSITION : 16.5N 49.5W ATCF IDENTIFIER : AL962022 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 14.09.2022 0 16.5N 49.5W 1010 36 0000UTC 15.09.2022 12 16.5N 52.2W 1010 34 1200UTC 15.09.2022 24 16.3N 54.8W 1010 36 0000UTC 16.09.2022 36 16.7N 56.0W 1009 39 1200UTC 16.09.2022 48 16.7N 59.0W 1009 36 0000UTC 17.09.2022 60 17.5N 61.6W 1008 32 1200UTC 17.09.2022 72 17.8N 63.7W 1007 31 0000UTC 18.09.2022 84 18.4N 65.5W 1006 32 1200UTC 18.09.2022 96 18.5N 67.7W 1005 35 0000UTC 19.09.2022 108 19.4N 68.7W 1002 40 1200UTC 19.09.2022 120 20.6N 70.1W 999 52 0000UTC 20.09.2022 132 21.2N 71.5W 997 53 1200UTC 20.09.2022 144 22.0N 72.6W 998 48

While we're concentrating on Invest 96L for good reason, folks should probably at least keep one eye on an AEW that's coming off Africa in ~12 hours. It has been quite active over W Africa. Several models (Euro, ICON, CMC) are now taking this at least to 50W in the MDR. The last 3 Euro runs haven taken it to at least the Lesser Antilles. The latest Euro takes this to just SW of PR as a TS moving WNW at 240 hours (9/24).

Convectively, the IR satellite looks more impressive than either GFS or CMC IR simulation maps look. Also, it looks more impressive than 24 hours ago, which itself looked rather impressive, itself. Shear is pretty low and SSTs are warming as it moves westward. This is moving over a climo favored region for development in mid Sept in a non-El Nino season. Several third year cold ENSO analogs have had genesis within 51-57W between 9/13 and 9/20. Thus, I remain confident this will become a TC and it will probably become a TD before 60W. It doesn't matter much to me how the season has gone so far. That being said, the UKMET (0Z) once again does nothing with it: TROPICAL DEPRESSION 96L ANALYSED POSITION : 15.7N 47.3W ATCF IDENTIFIER : AL962022 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 14.09.2022 0 15.7N 47.3W 1011 24 1200UTC 14.09.2022 12 CEASED TRACKING

12z Euro looks to be taking a little bit further SW track based on 96 hours, when the very weak low center is 200 miles south of PR. Edit: At 192, it is in the W Caribbean with a strong high to its north. Upon further review, the 12Z Euro seems to be combining 96L with some energy coming from the SW Caribbean. Anyone notice this? So, I'll need to later look at the 6 hour maps to see exactly where 96L tracked. And upon even more review: Check out the 12z Euro 850 mb vorticity maps. If you look closely, the NE portion of the 240 hour Bahamas low actually is associated with vorticity that is still over Africa, not the low now just offshore Africa, and won't come off til hour 48! I mean this vorticity speeds like a racehorse across the MDR! This is pretty fascinating.

TWO remains 30%/40% but the wording seems slightly less bullish: Tropical Weather Outlook NWS National Hurricane Center Miami FL 200 PM EDT Tue Sep 13 2022 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. Central Tropical Atlantic: Showers and thunderstorms associated with a tropical wave located about 1000 miles east of the Lesser Antilles have changed little in organization since this morning. Although environmental conditions are only marginally conducive, some gradual development of this system is possible over the next few days. A tropical depression could form while the system moves westward to west-northwestward over the tropical Atlantic and approaches the Leeward Islands on Friday. * Formation chance through 48 hours...low...30 percent. * Formation chance through 5 days...medium...40 percent.

The 12Z ICON is a bit further south and a little weaker with it initially getting to just S of PR at 120 hours before later curving NW and then N while strengthening into a H. It ends up just E of the SE Bahamas, which is the furthest W of any run. Is this a sign that there this will keep trending SWard on later runs? I wouldn't be surprised if this ends up in the Gulf based partially on analogs fwiw. The 12Z GFS does ~nothing with this through 204. Its vorticity gets into the W Caribbean and may be a hint to consider. For the 2nd run in a row, the 12Z CMC has this as a TC in the Gulf with this run having it as a TS in the far E Gulf at 192. It then turns west and ends up as a H in the W GOM aiming for TX. The 12Z JMA, which had this as a TC the prior two days, is slightly weaker through 72 (1012 mb vs 1011 mb near the LAs). The rest of the run won't be for awhile. The 12Z UKMET, which has it initially only because that's how this model handles all Invests, drops this immediately afterward: TROPICAL DEPRESSION 96L ANALYSED POSITION : 15.3N 46.0W ATCF IDENTIFIER : AL962022 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 13.09.2022 0 15.3N 46.0W 1011 25 0000UTC 14.09.2022 12 CEASED TRACKING

Thanks. Something to keep in mind. For those who haven't seen it, there's a new thread for this now that it has been designated as Invest 96L:

Invest 96L was just designated. Other than the precursor to Earl, this AEW to the best of my memory has had the most convection this far west in the MDR (40-45W) since the precursor to Bonnie way back in late June. The first model run with this as a TC was the UKMET way back at 12Z on September 4th though that had tropical genesis way too early (Sept 9th near 26W). Since then, just about every operational model has had this on some runs though it is still on and off. For example, the 6Z Euro dropped it as a TC after having it on the prior two runs. A good number of EPS and GEFS members have shown this as a hurricane threatening the CONUS Sept 22-26, including quite a few of them landfalling in the SE, some in the Gulf, and even a few runs in the NE US including one on NYC. There are eight third year cold ENSO analog seasons I've been following. Among those, three of them had either the biggest or near the biggest impact of the entire season (strongest impact overall Gulf coast of FL) become a TC between 51W and 57W and during the period 9/13 and 9/20 fwiw. TWO odds have just increased to make this a 5 day orange from the previous lemon: ZCZC MIATWOAT ALL TTAA00 KNHC DDHHMM Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Tue Sep 13 2022 For the North Atlantic...Caribbean Sea and the Gulf of Mexico: 1. Central Tropical Atlantic: Conventional and Low-earth orbit satellite data indicate that showers and thunderstorms associated with a tropical wave located about midway between the west coast of Africa and the Windward Islands have increased and become better organized since yesterday afternoon. Further development of this system is possible and a tropical depression could form over the next several days while it generally moves westward to west-northwestward over the central tropical Atlantic and approaches the Leeward Islands on Friday. * Formation chance through 48 hours...low...30 percent. * Formation chance through 5 days...medium...40 percent.

I recall past large moist AEWs embedded in lots of surrounding dry air seeming to do well. It is almost as if there is a moat protecting the moisture from the nearby dryness. We're still 5-6 hours from DMAX, too. Edit: The 0Z UKMET dropped it again just as it did on yesterday's run. I'm talking about the textual output. However, the map does show a weak surface low over the Leewards at 72 hours fwiw.

Yeah, I just saw that the 18Z Euro now has TCG. No recent Euro run had had this. That means just about all of the latest operational runs are developing this. Looking at the very impressive convection and the strong model support, and when considering analogs as well as near peak season climo in mid September, I'd now be quite surprised if this doesn't become a TC. Just looking at it, it is screaming genesis. It doesn't at all resemble the many dry AEWs of recent weeks. Who's to say that this won't be the most impactful storm of the season? Keep in mind that should this end up a big deal that the UKMET of 8 days ago was the first model to show TCG for this.

Other than the precursor to Earl, I can't recall any other AEW with nearly this much convection since the precursor to Bonnie in late June. I think it is going to eventually lead to a TC though it may take many days to do so.

Mike, I just look at the individual members on Tropical Tidbits and see where they go.

That post was based on just hour 240. Going to end of 12Z EPS (360) as regards the CONUS, it is active Sept 21-26 with 9 H landfalls: 1 on NYC, 3 on SC, 4 on FL (Cape Canaveral, Keys, Tampa, E Panhandle), and 1 on MS. So, a US hit from the Gulf could very much be in play here, especially if there's a delay in development. I continue to have the Gulf coast of FL as the highest seasonal risk area based on 8 ENSO analogs. Edit: The 18Z GFS has the Gulf at risk from this as it is very slow to develop it.

The 12Z EPS is another busy run. Climo for 9/22 for members east of the Bahamas would favor recurve and that's what they mostly do here. But there are also many members either within the Bahamas (some recurve and some don't; some actually turn left and are hard to assess) or near Cuba (no recurves).

The 12Z JMA fwiw (I know it isn't a good model) is the 2nd run with a TC from this 40W AEW after the similarly tracking TC that was on the 12Z yesterday. Today's gives the Virgin Islands to PR 6-7" of rainfall due to slow movement of it as a strengthening TD. The 192 has a strengthening TS just east of the SE Bahamas turning north. It is hard to tell if this would have continued much further north because there's a new upper high then starting to build along the east US coast to its north in response to a strong digging NW US trough. My guess is that this new high would have at least slowed it down and possibly turned it back NW to WNW for a period of time:

12Z Euro 216 has a scary setup for the SE US with TCG from this same AEW that is now near 40W on days 8-9 Bahamas and a strong high to its north. It then moves very slowly closer to S FL but still in the Bahamas at 240 as the blocking high starts to weaken some in response to an upper MW trough. It appears to me that regardless of the final outcome, this is likely going to be a long drawn out situation due to projected very slow movement of this AEW/weak steering currents. We could easily be dealing with this for the better part of two weeks.

Regarding this same AEW now near 40W: I don't know if it is drunk, but 12Z GEFS fwiw is for some reason by far the most active run since 5 days ago with 5 of 31 members as hurricanes near and just east of the SE Bahamas on Sept 19th. There's not much development til Sept 16th after passing 55W near and just east of the Leewards. By Sept 21st, 8 members are hurricanes and 2 are each a TS.

Regarding the AEW near 40W, the 0Z UKMET dropped it again, but the 12Z just brought it back once more only to have it dissipate in the NE Caribbean while it is moving WNW as it runs into Hispaniola: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 66 HOURS FORECAST POSITION AT T+ 66 : 16.6N 54.6W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 15.09.2022 72 16.5N 55.7W 1011 28 0000UTC 16.09.2022 84 16.6N 58.8W 1009 31 1200UTC 16.09.2022 96 17.0N 61.6W 1009 32 0000UTC 17.09.2022 108 17.1N 64.4W 1008 30 1200UTC 17.09.2022 120 17.5N 67.3W 1008 28 0000UTC 18.09.2022 132 CEASED TRACKING

When will it end? I got my AC working again but here comes more heavy thunderstorms, this time in a line with lots of CTG lightning. Edit: Once again, I got well over 1" and it was within just 30 minutes. Street flooding again. Standing water throughout the yards.

The 12Z EPS is suddenly MUCH more active with this (the AEW near 40W)! This is the most active EPS with this in days and is one of the most active with it yet! I count 12 hurricanes amongst the 51 members. So, that means that at 12Z that the UKMET, JMA, and the EPS are much more active with this and the strongest with this in days (and ever for the JMA). Maybe this is going to be a sleeper after all? Edit: A new convection tower is popping as the sun sets (so still not far after DMIN) near 11N, 40.5W, which may be near the strongest vorticity/weak surface low. Lets see whether or not this expands into DMAX later tonight. Edit: I count nearly 20 hurricanes among the 51 members (~40%) later in the run with some really scary runs for the SE US 9/22-26. This has to be one of the most threatening EPS runs for the SE this season to date! I count 7 hurricane hits on the SE (1 FL, 1 GA, 2 SC, 3 NC). In addition, I see 2 direct hits on New England. Yikes, hoping this is just a scary tease!

Now we can add the 12Z JMA to the 12Z UKMET with a TC from this. I know the model sucks overall, but a JMA 168 is far better than a GFS 384 and it is fwiw the first JMA run to ever have a TC from this AEW. This shows a strengthening TD moving slowly NW in the NE Caribbean. This leads to as much 4" of rainfall in the far NE Caribbean..so this isn't just a weak low on here:

IF this AEW near 40W were to turn out to be a sleeper and actually become a TC in the MDR on September 15th near 54W as the 12Z UKMET has, it would be very similar in terms of location and date to the geneses of what turned out to be big impact storms in three of the eight 3rd year cold ENSO analogs fwiw: - 1975: Eloise formed 9/13 near 54W, was the first TS in the MDR that season, and had the biggest impact of any TC that year: - 1917: #4 formed 9/20 near 57W and was the first MDR storm in 3 weeks. This also had the biggest impact of any TC that season: - 1894: #4 formed 9/18 near 51W and was the first MDR storm in nearly 3 weeks. This was among the highest impact storms of the season:

Check this out. The UKMET, which was the first model to have this in the 12Z run exactly one week ago and had completely dropped it in the prior four runs ending with 0Z today, just brought this back at 12Z. It has it as a TS moving WNW in the E Caribbean at the end of the run after forming east of the Lesser Antilles at hour 90: MET OFFICE TROPICAL CYCLONE GUIDANCE FOR NORTH-EAST PACIFIC AND ATLANTIC GLOBAL MODEL DATA TIME 1200UTC 11.09.2022 NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 90 HOURS FORECAST POSITION AT T+ 90 : 16.7N 53.7W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 15.09.2022 96 17.0N 55.1W 1009 36 0000UTC 16.09.2022 108 16.3N 57.9W 1008 37 1200UTC 16.09.2022 120 16.9N 60.0W 1008 38 0000UTC 17.09.2022 132 16.9N 62.2W 1007 32 1200UTC 17.09.2022 144 17.6N 64.4W 1006 37