Tropical Storm Carlotta strengthening, expected to become a hurricane
Tropical Storm Carlotta formed in the East Pacific a few hundred miles south of the Mexico and Guatemala border last night, and is poised to become the second hurricane of the 2012 Pacific hurricane season. As of the latest advisory from the National Hurricane Center, maximum sustained winds are up to 45 mph and the minimum barometric pressure is down to 1000 millibars. The cyclone is moving towards the northwest at 9 mph. Also of note, the Government of Mexico has issued a Hurricane Warning for the Mexican coastline from Salina Cruz to Punta Maldonado. A Hurricane Watch remains in effect from east of Salina Cruz to Barra De Tonala and from west of Punta Maldonado to Acapulco. Early visible satellite loops reveal that Carlotta remains a well-orgainzed, and organizing, tropical storm with numerous rain bands wrapping into a Central Dense Overcast. Satellite intensity estimates are 45 kt. (50 mph) from TAFB, 35 kt. (40 mph) from SAB, and 50 kt. (60 mph) from CIMSS-ADT.
Figure 1. Visible satellite imagery of Tropical Storm Carlotta.
The forecast for Carlotta
Carlotta lies in an environment of light vertical wind shear, Sea Surface Temperatures near 30 °C, and Ocean Heat Content values of 30-35. These conditions are expected to stay favorable for further intensification, and it appears that Carlotta will become a strong Category 1 or weak Category 2 hurricane before landfall in roughly 60 hours. The latest SHIPS model run gave Carlotta a 57% chance of 25-kt rapid intensification and a 33% chance of 30-kt rapid intensification; both of these percantages lie well above the typical 11.7% and 7.9%, respectively. After 48-60 hours out, it appears Carlotta will begin a slow weakening trend as it meanders near the coast of Mexico. The intensity forecast for this entry will lie slightly above the National Hurricane Center's, as it appears that Carlotta will not move far enough inland to induce rapid weakening and dissipation. A few of the global models reveal that the system could reemerge off the coast between 72-96 hours out and restrengthen, including the reliable LGEM. This will be the solution for now, although it all depends how far Carlotta makes it into Mexico before the ridge over Mexico breaks down.
Carlotta is currently being steered by an upper-level trough of low pressure to the west of the storm as seen on water vapor imagery and a small ridge of high pressure in the Southwest Caribbean. Looking at the global models, this pattern is forecast to continue for the next two days before the aforementioned ridge of high pressure builds across Mexico. Until then, a northwest motion is expected and Carlotta could make landfall between 48-60 hours out. Afterwards, a more westward motion is likely followed by the storm becoming nearly stationary as the ridge across Mexico breaks down and an upper-level trough develops across the Gulf of Mexico. There are indications that the storm will be pulled northward into the Bay of Campeche afterwards, but will not talk much about that until the next update.
INIT 14/1500Z 40 KT 45 MPH
12H 15/0000Z 50 KT 60 MPH
24H 15/1200Z 55 KT 65 MPH
36H 16/0000Z 80 KT 90 MPH
48H 16/1200Z 85 KT 100 MPH...LANDFALL & INLAND
72H 17/1200Z 65 KT 75 MPH...NEAR COAST
96H 18/1200Z 45 KT 50 MPH...NEAR COAST
120H 19/1200Z 50 KT 60 MPH...OVER WATER
Carlotta is going to be a life-threatening event for residents living across the warning area. Hurricane conditions are likely to be experienced along the coastline, with tropical storm-force winds further inland. Storm surge is also a concern for the coastline with the storm expected to make landfall near the time of astronomical high tide. Large and dangerous waves will cause major beach erosion, and rip currents will be a serious threat to persons in the water. Carlotta is expected to produce rainfall between 3-5 inches...with isolated totals near a foot...over the Mexican states of Guerrero, Oaxaca, Chiapas, and Guatemala. Significant flooding and mudslides are expected.
Figure 2. Latest National Hurricane Center track forecast for Tropical Storm Carlotta.