000 WTPZ42 KNHC 161437 TCDEP2 Hurricane Norma Discussion Number 9 NWS National Hurricane Center Miami FL EP172017 900 AM MDT Sat Sep 16 2017 Norma displayed a large convective band that wrapped most of the way around the center overnight. This band appears to be fragmenting this morning, though a new rainband has developed closer to the center. The Dvorak Current Intensity numbers from both SAB and TAFB remain 4.0 and thus the maximum winds are kept at 65 kt. However, the ADT and AMSU estimates are below hurricane force, so my initial intensity may be somewhat high. An Air Force reconnaissance mission will be investigating Norma around 20Z, so we should have a more accurate assessment of the intensity this afternoon. While the vertical shear is currently low and should remain that way for the next few days, the hurricane no longer has a well-defined outflow channel to its south and the upper-level divergence appears to be less conducive. Additionally, a prominent tongue of dry air seen in the total precipitable water imagery has wrapped around the southern semicircle about 200 nm from the center. Model guidance suggests that the mid-level humidities should dry substantially while Norma encounters increasingly cooler SSTs during the next few days. The official intensity forecast shows some slight intensification followed by a faster decay compared with the previous advisory. This forecast is based a blend of the LGEM statistical and HWRF/COAMPS dynamical guidance. Norma continues to be nearly stationary, though a developing deep-layer ridge over central Mexico/Gulf of Mexico should begin moving the hurricane toward the north later today. A motion toward the north-northwest or northwest should then continue for about three days. By days 4 and 5, a substantially weaker Norma is anticipated to meander while located just west of southern Baja California. The official track forecast is based upon the HFIP Corrected Consensus Approach and is slightly east of the previous advisory for the next two days and then about the same thereafter. FORECAST POSITIONS AND MAX WINDS INIT 16/1500Z 19.3N 110.1W 65 KT 75 MPH 12H 17/0000Z 19.7N 110.0W 70 KT 80 MPH 24H 17/1200Z 20.8N 110.4W 70 KT 80 MPH 36H 18/0000Z 21.8N 110.8W 65 KT 75 MPH 48H 18/1200Z 22.6N 111.3W 60 KT 70 MPH 72H 19/1200Z 23.5N 112.5W 50 KT 60 MPH 96H 20/1200Z 24.0N 113.0W 35 KT 40 MPH 120H 21/1200Z 24.5N 112.7W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Landsea