{"id": "1218493646051704835", "title": "Tropical Cyclone Discussion", "adv_date": "2026-10-13T21:00:00Z", "msg": "787\nWTPZ45 KNHC 132059\nTCDEP5\n \nHurricane Simon Discussion Number  26\nNWS National Hurricane Center Miami FL       EP202026\n200 PM MST Tue Oct 13 2026\n \nSimon's structure this afternoon has been more or less steady state \nas its small eye continues to be discernible on both visible and \ninfrared images. However, the surrounding eyewall cloud top \ntemperatures have warmed a bit this afternoon, though it is unclear \nif this is a diurnal fluctuation or evidence of some cooler ocean \nupwelling given its slow motion. The most recent high-resolution \nmicrowave image was an WSFM pass at 1338 UTC, which showed a nearly \nclosed eyewall and improvement from earlier imagery. The eye \nsignature can also be picked up on the edge of the Cabo San \nLucas, Mexico radar. The D-MINT mean estimate associated with the \nWSFM pass was 79 kt, and the initial intensity is held at 80 kt \nthis advisory, on the higher end of the intensity estimates. A \npartial Metop-B scatterometer pass was useful to indicate how \ncompact Simon's wind field has become, with 34-kt winds now only \nextend out an estimated 30 n mi.\n \nThe initial motion now appears to be a south of due west drift, or \n260 degrees at 2 kt. Compared to this morning, the forecast track \nreasoning has not changed a ton. The small hurricane is currently \njust on the south side of a saddle point, or col, in the steering \nflow. Simon's future track is very sensitive to which side of this \npoint the hurricane is located, with light steering currents \nprevailing leading to slow motion. In the latest round of guidance, \nall of the hurricane-regional models show a more substantial \nsouthward track this afternoon while Simon remains in very light \ndeep-layer southerly steering. While the ECMWF forecast is further \nnorth, it was initialized almost a full degree further north of \nwhere Simon was located at 12 UTC, placing it over or just on the \nnorth side of the saddle point. The Google Deepmind ensembles, which \noften favors this initialization, jump north in the short term, \nwhich appears unrealistic. Thus, the latest NHC track forecast is \ngoing to place a little more weight on the hurricane-regional model \ntracks which had a better initialization, showing a little more \nsouthward motion over the next 24-36 h, albeit as a snail's pace. \nThis track still shows a small cyclonic loop and is south of the \nprevious track forecast. After 48 h, the large-scale synoptic \npattern finally begins to change, where a deep-layer cutoff low digs \ninto southern California. This pattern will induce more southerly \nenvironmental flow over Simon, and should dislodge it from this very \nstagnant steering pattern assuming it doesn't move as far south as \nthe HAFS-A/B track aids. The NHC track forecast still shows Simon \ngaining latitude and turning more north-northwest in 60-72 h and \nlies closest to the HFIP Corrected Consensus Approach (HCCA) track. \nThis could bring Simon closer to the coast of Baja California Sur as \nit moves up the Gulf of California. However, there remains a wide \nvariety of track solutions that could verify, from well south of \nBaja California northward to mainland Mexico over the next 5 days.\n \nSimon has maintained a relatively healthy appearance today with a \nwell-organized inner core. As stressed earlier, very small \nhurricanes like Simon are known to be sensitive to small changes in \ntheir environmental conditions that could result in rapid changes in \nintensity, either up or down. Environmental conditions are \nfavorable, with shear over Simon expected to remain low for the next \n48 h with sea-surface temperatures (SSTs) in the 28-30 C range. \nAssuming Simon does not completely stall and upwell cooler ocean \nwaters, some intensification could occur. With that said, there is \nan extreme range of intensity solutions over the next 48 h, from \nintensifying into a Category 4 hurricane (HAFS-A) to weakening to a \ntropical storm (HMON). Given the current structure, the latest NHC \nintensity forecast now shows some intensification, but remains well \nunder the latest HAFS-A forecast and is closest to the ECMWF LGEM \nguidance. After 48 h, southwesterly vertical wind shear is forecast \nto increase rather quickly, and the small sensitive Simon is \nforecast to weaken even as it moves over warmer SSTs when it tracks \nnorthward. This latest forecast is initially on the high side of the \nguidance, but falls back to the middle of the guidance envelope \nafter \n72 h.\n \nIt is worth stressing that this remains a very low confidence\nforecast for both track and intensity, and interests in west-central\nMexico and Baja California Sur should continue to closely monitor\nthe latest updates. While mainland Tropical Storm and Hurricane\nwatches have been discontinued, new watches and warnings could be\nrequired over the next day or two as Simon's ultimate forecast comes\ninto better focus.\n \n \nKey Messages:\n \n1. Simon could approach Las Islas Marias on Wednesday and the coast\nof western Mexico later this week at or near hurricane strength, and\na Hurricane Watch is in effect for a portion of these areas.\nInterests in west-central Mexico and Baja California Sur should\ncontinue to closely monitor the latest updates to Simon's forecast.\nChanges to watches and warnings could be required over the next day \nor two based on the latest forecast trends.\n \n2. Large swells will affect portions of the southwestern and\nwest-central coasts of Mexico over the next several days. These\nswells are likely to cause life-threatening surf and rip current\nconditions.\n \n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  13/2100Z 20.2N 107.5W   80 KT  90 MPH\n 12H  14/0600Z 20.0N 107.8W   85 KT 100 MPH\n 24H  14/1800Z 19.8N 108.1W   90 KT 105 MPH\n 36H  15/0600Z 19.5N 108.0W   90 KT 105 MPH\n 48H  15/1800Z 19.8N 107.6W   85 KT 100 MPH\n 60H  16/0600Z 21.0N 107.8W   70 KT  80 MPH\n 72H  16/1800Z 22.6N 108.8W   60 KT  70 MPH\n 96H  17/1800Z 24.4N 110.2W   45 KT  50 MPH...NEAR BAJA CALIFORNIA \n120H  18/1800Z 28.8N 111.1W   30 KT  35 MPH...POST-TROP/INLAND\n \n"}