| You can't even write the NHC discussion early. "The center has become exposed to the southwest of the remaining deep convection due to moderate southwesterly shear and dry air." That was so last hour. (Okay, it is still on the SW corner of the new ball of convection.) And while Danny was perhaps as weak as the current NHC intensity earlier, it seems to be getting stronger now. TROPICAL STORM DANNY DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL AL042015 1100 PM AST SAT AUG 22 2015 Satellite imagery and data from an earlier NOAA Hurricane Hunter aircraft mission indicate that Danny has continued to quickly weaken. The center has become exposed to the southwest of the remaining deep convection due to moderate southwesterly shear and dry air. The earlier SFMR data supported an intensity of 50 to 55 kt around 0000 UTC, and since the organization of Danny has continued to decrease the advisory intensity has been lowered to 50 kt. The next NOAA and U.S. Air Force Reserve reconnaissance missions into Danny are scheduled for 0800 and 1200 UTC, respectively. Danny is expected to remain within a hostile environment consisting of dry mid-level air and moderate to strong southwesterly shear. This should result in additional weakening. Due to the fast rate of weakening Danny experienced today, the new NHC intensity forecast is significantly lower than the previous advisory, and is in best agreement with the HWRF and LGEM guidance. The NHC forecast now shows Danny weakening to a tropical depression within a couple of days and dissipating by day 5. Both of these events could occur sooner. In fact, the ECMWF, GFS, and UKMET all show Danny degenerating into a trough of low pressure by the time it nears Hispaniola in 2 to 3 days. Danny appears to have turned westward as anticipated, with an initial motion estimate of 275/13. The overall track forecast philosophy remains unchanged from the previous advisory. The cyclone should continue on a general westward motion during the next 24 to 36 hours. After that time, Danny is forecast to turn west- northwestward to the south of a low-level ridge over the western Atlantic. The dynamical models are in relatively good agreement on this scenario, and the updated NHC track is similar to, but a little south of, the previous advisory primarily due to the more southward initial position and current westward motion. Since Danny has rapidly weakened today and there is a reasonable possibility that it will be below tropical storm strength while moving through the Leeward Islands, the governments of the various islands have elected to maintain tropical storm watches at this time. Additional watches or warnings could still be required for portions of the Leeward Islands, the Virgin Islands, and Puerto Rico on Sunday if Danny does not weaken as quickly as forecast. FORECAST POSITIONS AND MAX WINDS INIT 23/0300Z 15.6N 54.7W 50 KT 60 MPH 12H 23/1200Z 15.9N 56.7W 45 KT 50 MPH 24H 24/0000Z 16.4N 59.3W 40 KT 45 MPH 36H 24/1200Z 16.9N 61.9W 35 KT 40 MPH 48H 25/0000Z 17.7N 64.4W 30 KT 35 MPH 72H 26/0000Z 19.5N 69.3W 25 KT 30 MPH 96H 27/0000Z 21.7N 73.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 28/0000Z...DISSIPATED $$ Forecaster Brown/Berg 5 day track: http://www.nhc.noaa.gov/refresh/graphics_at4+shtml/023703.shtml?5day?large#contents |