Wednesday, July 18, 2012

West To Be Tickled by Fabio
Try and contain your excitement.  The west is about to be tickled by Fabio.  Sorry ladies, we're not talking about the Italian model and actor (pictured above) that graced the cover of romance novels back in the day.  Nope, we're talking about the remnants of former tropical cyclone Fabio.

Fabio was once a hurricane but has weakened and is now classified as a post-tropical cyclone, a phrase used to describe a cyclone that has lost the characteristics of a tropical cyclone.  Fabio is presently moving northward off the Baja coast, with his "big hair" cirrus blowoff streaming over southern California.

1200 UTC 16 Jul – 1200 UTC 18 Jul 2012 IR Satellite loop with
GFS precipitable water (contours) and dynamic tropopause (color filled)
Tropical cyclone remnants are an important part of the North American monsoon system, especially for southern California.  Corbosiero et al. (2009) show that while only about 10% of all eastern North Pacific tropical cyclones bring rainfall to the southwest United States, they account for about 15–25% of the warm season (16 Jun–15 Oct) rainfall in southern California and northern Baja California.

Percentage of warm-season (16 Jun–15 Oct) precipitation
associated with eastern North Pacific tropical cyclones.
Source: Corbosiero et al. (2009).
The climatology is dominated by some major events, including the remnants of Hurricane Doreen (1977), which brought up to ~60 mm (2.36 inches) of precipitation to some locations in California and Nevada and about 95% of the warm-season total in some regions.

Source: Corbosiero et al. (2009)
The GFS projects that Fabio will bring a surge of high precipitable water air into southern California today and tomorrow, following a path just west of that of Doreen (1977). 

0600 UTC 18 Jul – 0000 UTC 20 Jul 2012 GFS sea level
pressure (contours) and precipitable water (shaded) forecast
However, the moisture and instability are fairly meager and will yield only a slight chance of showers and thunderstorms over southern California today and tonight.  Moisture from Fabio will eventually stream through Nevada, but this will only yield a slight chance of showers and thunderstorms.   

Fabio may be a model, but meteorologically, he's a tease.   

1 comment:

  1. It looks like he has recently crossed the 65F isotherm on his way north. Too bad the water is so cold in this region, or else this would be an excellent rainfall producer for much of the western U.S.