Invest 95E organizing; Invest 95L likely to become Chris
Invest 95E in the East Pacific has been slowly organizing over the past 24 hours and is now the closest to becoming a tropical depression than any point in its previous life. Visible satellite imagery and an earlier ASCAT pass reveals that cyclonic turning associated with the disturbance is becoming better organized, as well as increased shower and thunderstorm activity around the center. The latest Tropical Weather Outlook from the National Hurricane Center gave Invest 95E a High chance, 60%, of becoming a tropical cyclone over the next 48 hours; I agree with these percentages. If this system develops over the next two days, tropical cyclone watches and warnings will likely be needed for the Pacific coast of Mexico.
Figure 1. Afternoon visible satellite imagery of Invest 95E.
The forecast for 95E
Invest 95E lies within an environment favorable for further slow intensification. The latest SHIPS model analyzed 15 knots of wind shear over the system. Sea Surface Temperatures lie near 27 °C, above the threshold needed to sustain a tropical cyclone, and RH values are roughly 75%. One main limiting factor for the development of Invest 95E is its proximity to the Mexican coastline. Once the system gets well-established, if it ever does, it may pull in dry air off the mountains of Mexico, which could disrupt its circulation. Most of the intensity models actually do not foresee any further development of Invest 95E, although the forecast will show the disturbance reaching tropical storm status in accordance with the latest ECMWF model run.
INIT 18/1800Z 25 KT 30 MPH
12H 19/0600Z 25 KT 30 MPH
24H 19/1800Z 30 KT 35 MPH
36H 20/0600Z 30 KT 35 MPH
48H 20/1800Z 35 KT 40 MPH
72H 21/1800Z 40 KT 45 MPH
96H 22/1800Z 20 KT 25 MPH...INLAND/DISSIPATED
Invest 95L likely to become Chris
A subtropical area of low pressure located about 400 miles east-northeast of Bermuda is poised to become Subtropical/Tropical Storm Chris over the next 24 hours. Visible satellite imagery reveals that deep convection has been sustaining itself, and even firing, around the center of circulation since roughly 1300 UTC. Latest FSU Cyclone Phase Diagrams show that, despite the fact that Invest 95L lies atop Sea Surface Temperatures cooler than needed for a full tropical transition, the disturbance is making the transition towards at least a partially tropical low. The latest ATCF file update showed 95L with 40 knot (45 mph) winds and a minimum barometric pressure of 1005 millibars. The system is moving towards the Northeast, away from the United States. The latest Tropical Weather Outlook gave Invest 95L a Medium chance, 50%, of becoming a tropical cyclone over the next 48 hours. I believe this percentage is too conservative, and I am giving it a High chance, 70%, of becoming a tropical cyclone over the next 48 hours.
Figure 2. Afternoon visible satellite imagery of Invest 95L.
The forecast for 95L
Invest 95L currently lies within an area of high wind shear, near 30 knots. However, considering the low is subtropical, this is having very little effect on the storm, and will likely never. The latest SHIPS model forecast reveals that wind shear should continue to lower as it has over the past 24 hours as it pulls away from a large upper level low to its southwest. In fact, the model shows that wind shear will drop to the moderate range over the next 12 hours, and may drop below 10 knots into the low range by this time tomorrow. Many of the global models show further development of this low by then, and there is a good chance it could be "Subtropical/Tropical Storm Chris" by this time tomorrow. The most accurate intensity model available to the public, LGEM, shows continued organization and intensification over the next 3 days, peaking as a high-end subtropical/tropical storm, before gradual weakening as 95L moves into cooler waters of the open Atlantic. It is possible that the system could acquire tropical characteristics if convection fires continually, but Sea Surface Temperatures will not allow this process to go by quickly. Our generally unreliable models show that 95L has already peaked. The ECMWF and GFS both agree that the disturbance should be absorbed by a large extratropical low in a few days. As aforementioned, Invest 95L is no threat to any landmasses, and should pose only a threat to shipping lanes.
INIT 18/1800Z 40 KT 45 MPH...SUBTROP. LOW
12H 19/0600Z 45 KT 50 MPH...SUBTROP. STORM
24H 19/1800Z 50 KT 60 MPH
36H 20/0600Z 55 KT 65 MPH
48H 20/1800Z 50 KT 60 MPH...POST-TROP/EXTRATROP
72H 21/1800Z 45 KT 50 MPH...POST-TROP/EXTRATROP