California Explosive Cyclogenesis

In the early morning hours of February 19, 1993, an explosively developing cyclone was just southwest of San Francisco. By late afternoon, it had developed an "eye" and was ravaging the coastline about 150 km north of San Francisco. The development of this system was very similar to that documented in the literature for so-called "polar hurricanes" (a term that has seen much debate in the literature). A manuscript documenting this system is in preparation. To see OAK sounding and hodograph for this case, February 19, 1993, click here.

AVHRR Visible Imagery, 2315 UTC, February 19, 1993

Information on this storm will appear in: Monteverdi, J.P., Null, A.J., Pagan, K.L. and E. Daghir, in preparation: An investigation of an explosively developing cyclone along the California coast.

The image shows the "eye" about to make landfall at Point Arena. Sustained winds at Point Arena and a number of coastal buoys in the vicinity were on the order of 70 miles per hour. Thunderstorms were occurring from San Francisco to Point Arena.






AVHRR Infrared Imagery, 2315 UTC, February 19, 1993

Information on this storm will appear in: Monteverdi, J.P., Null, A.J., Pagan, K.L. and E. Daghir, in preparation: An investigation of an explosively developing cyclone along the California coast.

The image shows the convection occurring east and northwest of the circulation center. Moderate instability characterized California southeast of the center with several severe thunderstorms developing in the eastern portions of the San Joaquin Valley and the foothills of the southern Sierra Nevada.






AVHRR Enhanced IR Imagery, 2315 UTC, February 19, 1993

Information on this storm will appear in: Monteverdi, J.P., Null, A.J., Pagan, K.L. and E. Daghir, in preparation: An investigation of an explosively developing cyclone along the California coast.

The two thunderstorms on the extreme southeastern portion of the image were severe. The southern-most storm produced a tornado near Visalia, CA and the one with the "v"-shaped temperature signature produced giant hail.









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