GaWx

0Z UKMET: stays OTS like every other UKMET and every Icon has done. Reminder: Coincidentally or not, the UKMET and Icon were the two best models by far for Ian by being the furthest to the right/SE coming into SW FL. 0Z UKMET ROPICAL DEPRESSION 09L ANALYSED POSITION : 22.0N 76.4W ATCF IDENTIFIER : AL092025 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 0000UTC 28.09.2025 0 22.0N 76.4W 1005 31 1200UTC 28.09.2025 12 23.2N 76.9W 1003 35 0000UTC 29.09.2025 24 24.6N 76.7W 1000 32 1200UTC 29.09.2025 36 26.7N 77.1W 998 43 0000UTC 30.09.2025 48 28.5N 77.4W 994 42 1200UTC 30.09.2025 60 29.2N 77.3W 991 38 0000UTC 01.10.2025 72 29.0N 75.9W 989 41 1200UTC 01.10.2025 84 29.7N 73.4W 987 47 0000UTC 02.10.2025 96 30.3N 69.6W 985 57 1200UTC 02.10.2025 108 31.6N 64.5W 984 54 0000UTC 03.10.2025 120 33.5N 59.8W 986 67 1200UTC 03.10.2025 132 34.8N 57.0W 992 48 0000UTC 04.10.2025 144 36.3N 56.0W 995 43 1200UTC 04.10.2025 156 37.7N 54.4W 999 39 0000UTC 05.10.2025 168 41.4N 49.5W 999 41

Thanks. Everyone’s wrong sometime, even you who has often been right. And 100+ isn’t a guarantee yet.

Note the bolded: the slower speed of movement has increased the chance of it staying away from the US: Tropical Depression Nine Discussion Number 6 NWS National Hurricane Center Miami FL AL092025 1100 PM EDT Sat Sep 27 2025 The depression this evening remains fairly disorganized, with convection mainly oriented in a north-south fashion with only a hint of banding on the northern side. A NOAA-P3 aircraft that has been flying through the system only found a peak 700 mb flight level wind of 34 kt about 60 n mi away from the center. Tail Doppler Radar (TDR) analysis from the aircraft also shows the center is quite broad at the 1 km level with the mid-level center tilted to the south with height. Based on the plane data, the initial intensity remains 30 kt this advisory, which is a little under the various satellite-based estimates, but close to a recently received scatterometer pass which had a peak wind of 31 kt. Aircraft fixes both at 700 mb and from the TDR analysis shows the cyclone is meandering right now, with a best guess at a motion of 310/2 kt. Over the next couple of days, the system should turn north-northwestward with a somewhat faster forward motion, moving within the flow between an upper trough over the southeast U.S. and a subtropical ridge over the Atlantic. This forecast brings the depression over the central and northwestern Bahamas through early Monday, then toward the southeast U.S. coast by Tuesday. It is notable to point out the system has been moving slower than anticipated over the last 12-24 hours, and this could have significant implications on its ultimate track. Even in the first 48 hours of the track, there is quite a bit of spread in the north-south direction in both the deterministic and ensemble model guidance. Faster tracks appear to interact more with the upper-level trough to the west, resulting in a track closer to the Carolina coastline, while slower tracks largely miss a direct interaction with this feature, and turn sharply east faster as Hurricane Humberto approaches from the east, eroding the mid-level ridging steering TD9 northward. Because it has been moving slower than expected, its becoming more likely its ultimate track will fall in the slower and sharper east camp. In response, the overall track guidance this cycle shifted slower and further east, and the NHC track forecast was shifted in that direction. The latest track roughly splits the difference between the ECMWF and GFS tracks, and lies quite close to the HCCA consensus aid, but still not as far south and east as the Google DeepMind ensemble mean (GDMI). The depression is now showing signs of intensification yet, with a broad diffuse structure on aircraft observations persisting. However, the intensity guidance is insistent that deep central convection will soon form near the center, helping to tighten up the surface wind field. While the cyclone will have some southerly shear to deal with, it does not appear to be prohibitively strong, only 15-20 kt for the next 48 hours in both the GFS and ECMWF-based SHIPS guidance. That, combined with warm 29-30 C sea-surface temperatures should promote steady intensification once a central core develops, and the NHC intensity forecast was nudged up a little higher showing a 70 kt peak in 48 hours. After this period is where the intensity forecast gets tricky. The large spread in north-south tracks also has a significant impact on the amount of shear the system will face in the 48-96 hour time-frame. Solutions that are further south have less shear to contend with and are generally stronger. For now, the latest intensity forecast will cap the peak intensity at 70 kt through the end of the forecast, close to the HCCA intensity guidance, but this could be conservative if the track shifts further south and east. The system could also interact with a baroclinic zone towards the end of the forecast, but because the forecast track remains over warm waters at day 5, extratropical transition won't be shown quite yet. Even if this further offshore track pans out, the wind field is expected to expand quite a bit, and given the expected storm structure, a risk of significant heavy rainfall, storm surge, and wind impacts is still possible for the southeast U.S. coast even if the storm center remains offshore. KEY MESSAGES: 1. The depression is expected to strengthen and bring tropical storm conditions to portions of the central and northwestern Bahamas through Sunday night. Tropical storm conditions are also possible along portions of the east coast of central Florida beginning Monday, where a Tropical Storm Watch is in effect. 2. Rainfall will continue to impact eastern Cuba and the Bahamas through the weekend, which will likely produce flash and urban flooding. Mudslides are possible in the higher terrain. 3. There is a significant threat of heavy rainfall early next week from portions of the east coast of Florida northward into the Carolinas, which could cause flash, urban, and river flooding. 4. The depression is expected to be at or near hurricane intensity when it is closest to the southeast U.S. coast early next week, where there is a risk of storm surge and wind impacts. Although it is too soon to specify the exact location and magnitude of impacts, residents should closely monitor the latest forecast updates and ensure that they have their hurricane plan in place. FORECAST POSITIONS AND MAX WINDS INIT 28/0300Z 22.4N 76.7W 30 KT 35 MPH 12H 28/1200Z 23.6N 77.0W 35 KT 40 MPH 24H 29/0000Z 25.5N 77.5W 50 KT 60 MPH 36H 29/1200Z 27.3N 77.9W 60 KT 70 MPH 48H 30/0000Z 28.7N 78.2W 70 KT 80 MPH 60H 30/1200Z 29.9N 78.1W 70 KT 80 MPH 72H 01/0000Z 30.4N 77.3W 70 KT 80 MPH 96H 02/0000Z 31.0N 75.0W 70 KT 80 MPH 120H 03/0000Z 31.5N 71.4W 70 KT 80 MPH $$ Forecaster Papin

Hardly moving! BULLETIN Tropical Depression Nine Advisory Number 6 NWS National Hurricane Center Miami FL AL092025 1100 PM EDT Sat Sep 27 2025 ...DEPRESSION MEANDERING TO THE SOUTH OF THE CENTRAL BAHAMAS... ...HEAVY RAINS EXPECTED TO CONTINUE OVER PARTS OF EASTERN CUBA AND THE BAHAMAS OVER THE NEXT DAY... SUMMARY OF 1100 PM EDT...0300 UTC...INFORMATION ----------------------------------------------- LOCATION...22.4N 76.7W ABOUT 220 MI...355 KM NW OF THE EASTERN TIP OF CUBA ABOUT 100 MI...160 KM SW OF THE CENTRAL BAHAMAS MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H PRESENT MOVEMENT...NW OR 310 DEGREES AT 2 MPH...4 KM/H MINIMUM CENTRAL PRESSURE...1004 MB...29.65 INCHES

Per recon, it hasn’t been moving NNW. Actually, there apparently was just a reformation of the weak center slightly to the SE per this. Overall, it has moved very little today so far:

I’ve received only ~0.90” of rain this month with about all of that way back on Sept 7th. Compare that to 17.1” in August!

Thanks to the second cat 5 of the season, Humberto, and future Imelda, ACE is progged to reach ~94 as of Sep 30th. That would be exactly the 1991-2020 avg! What a comeback! But the Euro Weeklies have been suggesting this could occur for several weeks, and recent seasons have been active late, especially during La Niña. With ~94 now forecasted as of 9/30, with the Euro Weeklies forecasting an above average Oct, mainly favorable MJO expected, weak La Niña, and recent active late seasons, a 120+ season total would be likely with even my preseason forecast of 139 being quite doable. A sub-100 is extremely unlikely now…I’d say 3% chance. @snowman19@PhiEaglesfan712

12Z GEFS are also initialized W of the implied 12Z position , which was ~76W. The mean 12Z GEFS init. is ~76.5-76.7W meaning that’s ~35-50 miles too far W.

1. 12Z CMC stays OTS just like Icon, GFS, and UK 2. Anyone notice this? Based on the 11AM (15Z) NHC position of 76.2W on a NW heading, it appears to me that the model consensus 12Z initializations are ~35-100 miles too far W with them closer to 76.5-77.3W as of 12Z. FORECAST POSITIONS AND MAX WINDS INIT 27/1500Z 22.0N 76.2W 30 KT 35 MPH

Note the 12Z UK initialization as of 12Z at 22.0N, 77.3W. It actually was per NHC ~21.7N, ~76W meaning it initialized ~100 miles too far WNW and still recurved pretty easily from US. That bodes well for chances for staying OTS from US.

Just like for all runs before, 12Z UK is again staying OTS from US with this run not as close to FL on its closest approach (175 miles offshore) vs last few runs: TROPICAL DEPRESSION 09L ANALYSED POSITION : 22.0N 77.3W ATCF IDENTIFIER : AL092025 LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 27.09.2025 0 22.0N 77.3W 1007 28 0000UTC 28.09.2025 12 21.3N 77.3W 1006 26 1200UTC 28.09.2025 24 23.4N 77.1W 1005 34 0000UTC 29.09.2025 36 24.7N 77.1W 1003 30 1200UTC 29.09.2025 48 26.2N 77.1W 1003 43 0000UTC 30.09.2025 60 27.5N 77.5W 1000 39 1200UTC 30.09.2025 72 28.3N 76.6W 997 35 0000UTC 01.10.2025 84 28.6N 74.6W 994 39 1200UTC 01.10.2025 96 34.6N 69.7W 977 69 0000UTC 02.10.2025 108 CEASED TRACKING —————— *Edit: Note the initialization as of 12Z at 22.0N, 77.3W: how is that compared to where it really was at 8AM?

12Z Icon stays OTS from US

The last frame of 6Z Euro has this stop its ENE movement and then suddenly drift back due W fwiw as Humberto accelerates away and the upper high builds enough to its N to change the steering. Although this is the only major op doing this, 40% of the 6Z EPS do not escape and most of those stall not too far offshore and then attain a W component of motion.

0Z Euro stays away from the US.

0Z CMC stays OTS unlike 12Z, which looped back to NC So far, all OTS with only Euro left

0Z: Icon stays OTS as has been case every run GFS stays OTS 2nd run in a row JMA goes out only 72 but implies it would again get pulled into Humberto and stay OTS UKMET stays OTS as (like the Icon) has been the case every run: NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 30 HOURS FORECAST POSITION AT T+ 30 : 23.5N 77.1W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 28.09.2025 36 23.5N 77.3W 1004 38 0000UTC 29.09.2025 48 25.0N 77.5W 1002 38 1200UTC 29.09.2025 60 26.5N 78.0W 1001 38 0000UTC 30.09.2025 72 28.1N 78.3W 998 43 1200UTC 30.09.2025 84 28.3N 78.5W 995 42 0000UTC 01.10.2025 96 27.6N 76.9W 993 38 1200UTC 01.10.2025 108 27.4N 74.6W 991 45 0000UTC 02.10.2025 120 27.8N 71.6W 989 45 1200UTC 02.10.2025 132 28.3N 68.0W 987 48 0000UTC 03.10.2025 144 28.8N 63.5W 989 66 1200UTC 03.10.2025 156 29.8N 59.3W 994 54 0000UTC 04.10.2025 168 30.3N 56.7W 997 41 ——————— CMC next

0Z GFS also likely not going to hit the US based on 78 but we’ll see.

0Z Icon is again OTS.

18Z Icon remained OTS. If this ends up not hitting the US, keep in mind that both the Icon and UKMET haven’t had even one run so far with anything even that close to a landfall. Those two models were the best with Ian by the way.

“Hilton Head landfall Thursday morning on euro” way out at hour 144 or so with devastating amounts of rainfall in SC. Then drifts S to near SAV.

Then per other sources it stalls just offshore for 24+ hours

12Z Euro H5 114 hits CHS:

It appears that way. We’ll see whether the run gets going again as it’s been stuck at hour 78 for nearly 15 minutes

12Z Euro to 78 looks similar to 0Z at 90

Other 12Z: Icon goes OTS again JMA hints at OTS but not sure since only to 72 UKMET goes OTS again like the Icon although it goes further NW than prior runs before going OTS NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 42 HOURS FORECAST POSITION AT T+ 42 : 23.3N 76.7W LEAD CENTRAL MAXIMUM WIND VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS) -------------- ---- -------- ------------- ------------- 1200UTC 28.09.2025 48 24.2N 76.7W 1007 33 0000UTC 29.09.2025 60 25.2N 77.4W 1004 34 1200UTC 29.09.2025 72 26.7N 77.8W 1003 38 0000UTC 30.09.2025 84 28.2N 77.6W 1001 36 1200UTC 30.09.2025 96 28.9N 78.5W 996 42 0000UTC 01.10.2025 108 28.7N 77.8W 994 40 1200UTC 01.10.2025 120 28.5N 76.6W 992 38 0000UTC 02.10.2025 132 28.7N 74.3W 991 46 1200UTC 02.10.2025 144 28.9N 72.2W 991 54 0000UTC 03.10.2025 156 28.7N 69.6W 992 63 1200UTC 03.10.2025 168 28.6N 68.4W 995 52