Invest 93E forms in the East Pacific
An area of showers and thunderstorms associated with a broad low pressure area in the East Pacific, dubbed Invest 93E by the National Hurricane Center, is showing signs of gradual development this evening. Visible satellite loops show a distinct low-level spin associated with the disturbance, and an earlier ASCAT pass revealed dual areas of cyclonic turning. The National Hurricane Center is currently giving 93E a Medium chance, 30%, of becoming a tropical cyclone over the next 48 hours. However, given its current satellite presentation and a plethora of conditions expected to continue working to its advantage, I believe the odds of tropical cyclone formation over the next 48 hours are much higher, near 70%. In fact, the latest SHIPS model forecast brings 93E up to 68 knots (~80 mph) at that time.
Figure 1. Evening visible satellite imagery of Invest 93E.
The forecast for 93E
An objective analysis from the Cooperative Institute for Meteorological Satellite Studies (CIMSS) reveals that Invest 93E is situated in a favorable environment for further strengthening. The invest is atop Sea Surface Temperatures of nearly 30 °C, and the latest SHIPS model initialized with 15 knots of wind shear and a 700-500 mb Relative Humidity value of 77%. Tropical Cyclone Heat Content values lie near 42, which falls short of the values typically needed for rapid intensification. Despite the fact that these values are expected to strengthen somewhat over the next 48-72 hours, it appears that slow to gradual intensification is favored. A majority of the global intensity models show 93E attaining tropical storm status in ~24 hours. If this were to be the case, it would be named "Carlotta", the third named storm of the 2012 Pacific hurricane season. The LGEM model forecast 93E to attain hurricane status in 72 hours, but a more bullish approach will be taken in this blog entry due to the fact that many of the other intensity models foercast the system to attain hurricane status by 60 hours out.
As for track, Invest 93E lies well south of a trough of low pressure across the Central United States and a ridge of high pressure across the Central and East Pacific. With both forces acting on the disturbance, a general west-northwest motion should continue for the next 48-72 hours. After that, the ridge of high pressure to the north of 93E should strengthen, forcing the system to turn westward. The GFS and ECMWF are even showing a southwest motion could ensue by 120 hours out. Regardless, Invest 93E is not forecast to be a threat to any landmasses at this time.
INIT 10/0000Z 25 KT 30 MPH
12H 10/1200Z 30 KT 35 MPH
24H 11/0000Z 35 KT 40 MPH
36H 11/1200Z 45 KT 45 MPH
48H 12/0000Z 50 KT 60 MPH
72H 13/0000Z 70 KT 80 MPH
96H 14/0000Z 80 KT 90 MPH
120H 15/0000Z 80 KT 90 MPH