000 WTNT42 KNHC 200853 TCDAT2 Tropical Storm Bret Discussion Number 7 NWS National Hurricane Center Miami FL AL022017 500 AM AST Tue Jun 20 2017 Bret continues to have a fairly well-organized appearance on satellite imagery, but the presentation on radar from Trinidad and Venezuela is not so impressive, with a lack of well-defined banding features. The structure of the cyclone continues to be characterized by a northward tilt of the vortex with height, so the center is estimated to be located near the southern side of the CDO. The initial intensity is held at 35 kt for this advisory, which is the mean of Dvorak T-numbers from SAB and TAFB. The intensity forecast reasoning remains about the same as before. No significant short-term strengthening seems likely while the circulation interacts with Venezuela today. In 24 hours or so, a weakening trend should commence due to strong south-southwesterly shear associated with an upper-level trough over the Caribbean Sea. The global models continue to be in good agreement that the system will dissipate over the west-central Caribbean in 2-3 days. The official intensity forecast is near or slightly above the intensity model consensus, IVCN. The forward motion has slowed just a bit from yesterday and is now around 290/18 kt. There continues to be little change to the track forecast philosophy. The flow on the southern side of a well-defined mid-level subtropical ridge should steer the cyclone on a west-northwestward to westward track for the next couple of days. The official track forecast lies between the latest ECMWF and GFS solutions and is close to the model consensus. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 10.6N 62.9W 35 KT 40 MPH 12H 20/1800Z 11.5N 65.3W 35 KT 40 MPH 24H 21/0600Z 12.4N 68.7W 35 KT 40 MPH 36H 21/1800Z 13.3N 72.7W 30 KT 35 MPH 48H 22/0600Z 13.6N 76.7W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 23/0600Z...DISSIPATED $$ Forecaster Pasch
BRET
000 WTNT43 KNHC 200852 TCDAT3 Potential Tropical Cyclone Three Discussion Number 3 NWS National Hurricane Center Miami FL AL032017 400 AM CDT Tue Jun 20 2017 Nighttime infrared satellite imagery suggests that the circulation associated with the low pressure area in the Gulf of Mexico is gradually becoming better defined. However, the system is struggling to maintain organized convection near the center, and the radius of maximum winds remains large. Based on this, the system is still maintained as a potential tropical cyclone. The low is moving erratically northwestward around the southwestern portion of a deep-layer ridge located over the western Atlantic and Florida. The large-scale models suggest this ridge will strengthen some during the next 36 hours or so and cause the low to turn a little more westward. This would be followed by a northward turn around the western end of the ridge and eventual recurvature into the westerlies. Overall, there has been a left shift of the track guidance models since the previous advisory. The new forecast track is also shifted left, but it is to the right of the model consensus, especially at 36-48 h. Given the nature of the circulation, though, and the fact that the wind and rain hazards extend well north and east of the center, users are encouraged to not focus on the details of the track forecast. The initial intensity remains 35 kt based on partial scatterometer overpasses and continuity from the previous advisory. Significant strengthening is unlikely due to strong vertical shear caused by an upper-level trough over the northwestern Gulf of Mexico and entrainment of dry air into the system. However, the large-scale models suggest slight strengthening before landfall, and thus the intensity forecast is unchanged from the previous advisory. One change from the previous advisory is that it now appears more likely that the system would become a subtropical cyclone than a tropical cyclone due to the current structure of the low and interaction with the aforementioned trough. That being said, development into a tropical cyclone remains possible. The primary hazard from this disturbance is expected to be heavy rainfall over portions of the central and eastern Gulf Coast. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 24.8N 90.1W 35 KT 40 MPH...POTENTIAL TROP CYCLONE 12H 20/1800Z 25.7N 91.0W 35 KT 40 MPH...SUBTROPICAL CYCLONE 24H 21/0600Z 26.6N 92.1W 40 KT 45 MPH 36H 21/1800Z 27.5N 93.0W 40 KT 45 MPH 48H 22/0600Z 28.9N 93.5W 40 KT 45 MPH 72H 23/0600Z 32.5N 93.5W 25 KT 30 MPH...INLAND 96H 24/0600Z 36.5N 88.0W 20 KT 25 MPH...POST-TROP/INLAND 120H 25/0600Z...DISSIPATED $$ Forecaster Beven
POTENTIAL TROPICAL CYCLONE THREE(CINDY)
