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Tropical Storm CARLOS Forecast Discussion Number 20
2015-06-15 16:40:25| National Hurricane Center (East Pacific)
Issued at 1000 AM CDT MON JUN 15 2015 000 WTPZ43 KNHC 151440 TCDEP3 TROPICAL STORM CARLOS DISCUSSION NUMBER 20 NWS NATIONAL HURRICANE CENTER MIAMI FL EP032015 1000 AM CDT MON JUN 15 2015 First-light visible satellite imagery indicates Carlos remains a very small tropical cyclone. An earlier GCOM-AMSR microwave pass also indicated the compact nature of the system, including a closed 5-10 nmi diameter eye. The consensus of satellite intensity estimates is 55 kt, but we'll hold the initial intensity at 60 kt pending the arrival of a United States Air Force Reserve hurricane hunter aircraft. The initial motion estimate is 290/05 kt. Carlos is expected to maintain a slow west-northwestward motion and move essentially parallel to the south-central coast of Mexico for the next 24-36 hours. After that time, there is a distinct bifurcation in the model guidance with how strong the mid-level ridge across northern Mexico and Texas is forecast to be. The GFS, UKMET, NAVGEM, HWRF, and the BAM models keep the ridge stronger and also weaken Carlos, resulting in the cyclone moving westward at 48 hours and beyond. In contrast, the ECMWF and GFDL models weaken the ridge and keep Carlos stronger, and gradually move the cyclone northwestward and then northward near the southwestern coast of Mexico during that time. Given that the large low pressure system currently located over the central Gulf of Mexico is forecast to move inland over Texas by 48 hours, which should act to weaken the mid-level ridge to the north and northeast of Carlos, the ECMWF-GFDL solution is preferred at this time. The NHC official track forecast is essentially just an update of the previous advisory, and lies close to a blend of the ECMWF, FSSE, and GFDL forecast tracks. However, only a slight deviation to the right of the forecast track would bring Carlos inland along the southwestern coast of Mexico. The very small size of Carlos makes the cyclone susceptible to small fluctuations in the vertical wind shear. However, the general trend in the GFS-based SHIPS intensity model is calling for the shear to decrease to less than 5 kt by 48 hours and beyond, which should allow for some strengthening to occur over 29C SSTs . Carlos is expected to weaken into a depression by 72 hours due to land interaction and an unfavorable thermodynamic environment, becoming a remnant low by 96 hrs, and dissipating by 120 hrs. The intensity forecast is similar to the previous advisory and closely follows the LGEM model. FORECAST POSITIONS AND MAX WINDS INIT 15/1500Z 17.0N 102.5W 60 KT 70 MPH 12H 16/0000Z 17.3N 103.3W 60 KT 70 MPH 24H 16/1200Z 17.8N 104.2W 65 KT 75 MPH 36H 17/0000Z 18.4N 105.0W 60 KT 70 MPH 48H 17/1200Z 19.4N 105.6W 50 KT 60 MPH 72H 18/1200Z 21.2N 106.1W 30 KT 35 MPH 96H 19/1200Z 22.8N 106.8W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 20/1200Z...DISSIPATED $$ Forecaster Stewart
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