{"id": "1209503091485114370", "title": "Tropical Cyclone Discussion", "adv_date": "2026-09-12T03:00:00Z", "msg": "682\nWTPZ44 KNHC 120250\nTCDEP4\n \nTropical Storm Norbert Discussion Number  10\nNWS National Hurricane Center Miami FL       EP142026\n500 PM HST Fri Sep 11 2026\n\nSatellite imagery indicates that the convective organization \nassociated with Norbert has changed little over the past several \nhours. A well-defined curved band of deep convection continues to \nwrap into the circulation around the western semicircle from the \nnorth, although cloud-top temperatures within the band have warmed \nslightly during the past few hours. The latest subjective Dvorak \nintensity estimate from TAFB maintains T3.5/55 kt, which harmonizes \nwell with the objective intensity estimates from UW-CIMSS ranging \nbetween 45 and 55 kt. Given these data and only modest changes in \nthe convective structure, the initial intensity is held at 55 kt.\n\nThe initial motion is west-northwestward, or 285/10 kt. This general \nwestward to west-northwestward motion is expected to persist through \nthe weekend as a low- to mid-level subtropical ridge remains \npositioned north of the cyclone. Thereafter, confidence on Norbert's \ngeneral motion is reduced as track models diverge significantly, as \nthe evolution of the mid-level ridge plays a vital role in the track \nforecast over the next several days. The GFS shows the ridge \nshifting eastward, causing Norbert to generally prevail westward, \nwhile remaining on the north side of the guidance envelope. On the \nother hand, the ECMWF showcases the aforementioned ridge building \nsouthward, steering Norbert more southwestward. The consensus aids \nsit snug in between these two solutions. The NHC track forecast \nsides largely with the previous forecast, which lies near the Google \nDeepMind ensemble mean. \n\nEnvironmental conditions appear favorable for some strengthening, \nand Norbert is forecast to become a hurricane within the next 24 h. \nThereafter, Norbert's intensity is expected to remain relatively \nconsistent, shuffling 5 to 10 kt difference throughout the forecast \nperiod. This will depend ultimately on the track, as discussed \nabove. A more northward track, more in line with the GFS, would find \nNorbert in a less favorable environment, where increasing vertical \nshear would weaken the system considerably. Conversely, the more \nsouthern track similar to the ECMWF, would bring Norbert into a more \nfavorable environment with less vertical wind shear, allowing \nNorbert to potentially strengthen. Given the competing scenarios \nthereafter, little change has been made to the previous intensity \nforecast, with some weakening still indicated early next week. The \nNHC intensity forecast is generally an update to the previous \nadvisory.\n\n \nFORECAST POSITIONS AND MAX WINDS\n \nINIT  12/0300Z 17.2N 126.6W   55 KT  65 MPH\n 12H  12/1200Z 17.4N 127.9W   60 KT  70 MPH\n 24H  13/0000Z 17.8N 129.8W   65 KT  75 MPH\n 36H  13/1200Z 18.2N 131.5W   65 KT  75 MPH\n 48H  14/0000Z 18.5N 133.3W   65 KT  75 MPH\n 60H  14/1200Z 18.7N 135.5W   55 KT  65 MPH\n 72H  15/0000Z 18.6N 137.3W   55 KT  65 MPH\n 96H  16/0000Z 18.0N 141.9W   55 KT  65 MPH\n120H  17/0000Z 16.3N 146.1W   55 KT  65 MPH\n \n"}