Tropical Cyclone Discussion
659 WTPZ43 KNHC 011441 TCDEP3 Tropical Storm Marie Discussion Number 2 NWS National Hurricane Center Miami FL EP132026 800 AM MST Tue Sep 01 2026 This morning's GOES-18 Proxy-VIS satellite imagery indicates that Marie is gradually becoming better organized. Deep convection with cold cloud tops of -81C is developing over the surface circulation center, and a spiral band is wrapping around the center from the southwest part of the cyclone. No changes yet in both the subjective and objective satellite intensity guidance, however, so the initial intensity is held at 40 kt for this advisory. The ocean is warm, the low- to mid-levels of the atmosphere are moist, and the deep-layer shear is low. Subsequently, strengthening is expected, and Marie should become a hurricane by Wednesday night. By the weekend, the GFS/ECMWF SHIPS statistical intensity guidance and the physics-based deterministic models indicate that Marie will encounter a drier, stable marine layer air mass while traversing progressively cooler oceanic temperatures. Accordingly, the NHC intensity forecast follows suit and shows Marie slowly weakening beyond day 4. An earlier 0707 UTC OSCAT-3 scatterometer overpass and a fortuitous 1247 UTC GPM/GMI image indicated that the surface center was a bit farther northeast than previously noted, and near the northwestern edge of the deep convective canopy. Marie's initial motion is estimated to be northwestward, or 315/8 kt. A mid-tropospheric subtropical ridge stretching from northern Mexico westward over the extreme eastern Pacific should steer the cyclone generally northwestward through Thursday. Afterward, the subtropical high should weaken in response to an amplifying mid- to upper-level trough approaching the west coast of the U.S. This change in the large-scale synoptic pattern is expected to slow Marie's forward speed. For the remainder of the forecast, the aforementioned mid- to upper-level trough should fill and lift northeastward, allowing the ridge to build and reestablish north of Marie and steer the system back toward the west-northwest through the weekend. There's still quite a bit of cross-track spread in the model suite beyond day 3, with one cluster indicating a north-northwestward motion while another model cluster shows a more west-northwestward trajectory. The official forecast reflects slight adjustments to the left of the previous forecast and favors a blend of the skilled NOAA HCCA consensus aid and the Google DeepMind FNv3 ensemble mean forecast. FORECAST POSITIONS AND MAX WINDS INIT 01/1500Z 15.0N 108.7W 40 KT 45 MPH 12H 02/0000Z 16.0N 109.8W 50 KT 60 MPH 24H 02/1200Z 17.1N 111.2W 60 KT 70 MPH 36H 03/0000Z 18.0N 112.4W 70 KT 80 MPH 48H 03/1200Z 19.0N 113.9W 80 KT 90 MPH 60H 04/0000Z 19.7N 115.6W 85 KT 100 MPH 72H 04/1200Z 20.3N 117.0W 85 KT 100 MPH 96H 05/1200Z 21.4N 119.8W 80 KT 90 MPH 120H 06/1200Z 22.3N 122.0W 75 KT 85 MPH