000 WTPZ42 KNHC 150255 TCDEP2 Tropical Storm Norma Discussion Number 3 NWS National Hurricane Center Miami FL EP172017 900 PM MDT Thu Sep 14 2017 The large circulation of Norma was well-defined in late afternoon visible satellite images, however, the colder convective cloud tops remain fragmented in infrared satellite imagery. Since the convective banding has not significantly improved this evening, the Dvorak data T-numbers have remained about the same as this afternoon, and the initial intensity of 40 kt is maintained for this advisory. Recent satellite fixes show that Norma is moving slowly northward or 360/5 kt. A large high pressure area over northern Mexico and an associated ridge that extends southwestward across the Baja California peninsula should keep Norma on a slow northward track during the next couple of days. After that time, the model spread significantly increases with the ECMWF and UKMET models turning Norma west-northwestward, taking it west or southwest of Baja California. The GFS and HWRF weaken the ridge and move Norma northward across Baja California Sur ahead of a mid-latitude trough that deepens southwest of southern California. The NHC forecast continues to follow the latter scenario since it is favored by the HFIP corrected consensus model and is also fairly close to the TVCN consensus aid. The updated track forecast is similar to the previous advisory, but the confidence in the track forecast remains quite low due to the usually large model disagreement. Norma is forecast to remain within a favorable environment of low vertical wind shear and over warm water, however, the large and sprawling structure of the tropical cyclone may temper the intensification rate in the short-term. As a result, the updated NHC intensity forecast is slightly lower than the previous advisory through 72 hours, and it is between the ICON intensity consensus and the slightly more aggressive HCCA consensus. Land interaction and increasing southwesterly shear is likely to lead to weakening later in the period. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 18.3N 109.3W 40 KT 45 MPH 12H 15/1200Z 18.7N 109.3W 50 KT 60 MPH 24H 16/0000Z 19.2N 109.3W 60 KT 70 MPH 36H 16/1200Z 19.7N 109.4W 70 KT 80 MPH 48H 17/0000Z 20.6N 109.6W 75 KT 85 MPH 72H 18/0000Z 22.7N 110.3W 70 KT 80 MPH 96H 19/0000Z 25.1N 110.6W 55 KT 65 MPH 120H 20/0000Z 27.5N 109.0W 35 KT 40 MPH...INLAND $$ Forecaster Brown