CoconutCandy
(User)
Fri Jul 08 2011 12:49 PM
Tropical Storm CALVIN Nearing Hurricane Strength

Tropical Storm 'Calvin', a few hundred miles off the Mexican coast, consolidated overnight, and the inner core convection organized sufficiently to form a closed eyewall feature, quite evident on a recent passive microwave imaging overpass.



And animated visible satellite imagery from this morning (as well as the above microwave picture) clearly portrays a moderately strengthening system, with new convective banding features now in evidence in the SW and NE quadrants of the storm.



From the latest NHC Bulletin ...

"THE CONVECTIVE SIGNATURE OF CALVIN HAS IMPROVED AS AN EYE-LIKE FEATURE IS EVIDENT FROM BOTH THE 1136Z SSMI IMAGERY AND THE FIRST VISIBLE IMAGES THIS MORNING. ... WITH IMPROVED SUBSEQUENT ORGANIZATION THE ADVISORY INTENSITY IS SET AT 60 KT."

However, it appears that 'Calvin' is about to peak as a tropical cyclone, as environmental parameters, especially cooler SST's, should significantly inhibit the system beginning in another 12 hours, or so.

"CALVIN HAS A LIMITED TIME FOR FURTHER INTENSIFICATION...AS IT IS ABOUT TO REACH THE COOL SST'S AND STABLE ENVIRONMENT SOUTH OF BAJA CALIFORNIA. SO DESPITE THE MODERATE EASTERLY SHEAR ANTICIPATED TO RELAX OVER THE NEXT FEW DAYS...THE CYCLONE IS PROJECTED TO PEAK IN ABOUT 12 HOURS AS A CATEGORY 1 HURRICANE WITH GRADUAL WEAKENING THEREAFTER."

Tropical Cyclone 'Calvin' is well west of Mexico, and is forecast to track WNW, even further from land, as it steadily weakens in the days ahead.

(Imagery courtesy Navel Research Lab, Monterrey)
...


CoconutCandy
(User)
Fri Jul 08 2011 07:41 PM
Hurricane CALVIN Peaking as Minimal Cat 1 Hurricane

As anticipated by the NHC and other guidance, 'Calvin' appears to be peaking this afternoon as a minimal Cat 1 hurricane, with peak sustained winds estimated to be near 75 mph.

Further inner core organization has transpired since this morning, depicting somewhat more robust appearing eyewall dynamics, with a robust cluster of thunderstorms with cloud tops of -80 degrees C or colder, but an overall decrease in associated banding features surrounding the storm could portend the harbinger of a slow but steady weakening trend expected beginning the next 12 to 18 or so hours.



The latest discussion from the NHC is revealing ...

"... CONVENTIONAL SATELLITE IMAGES AS WELL AS MICROWAVE DATA HAVE BEEN SHOWING AN INTERMITTENT EYE FEATURE.

BASED ON THE CURRENT CLOUD PATTERN AND THE INCREASE IN THE DVORAK T-NUMBERS SINCE THIS MORNING ... CALVIN HAS BEEN UPGRADED TO HURRICANE STATUS WITH AN INITIAL INTENSITY OF 65 KNOTS."


However, as mentioned above, 'Calvin' is expected to be a short lived system ...

"THE WESTERN PORTION OF THE CIRCULATION IS ALREADY OVER COOLER WATER WHERE THE CONVECTION HAS BEGUN TO WEAKEN. IT APPEARS THAT CALVIN HAS REACHED ITS PEAK INTENSITY ... THE GENERAL TREND IS FOR CALVIN TO WEAKEN."

It will be interesting to see if tonight's approaching diurnal convective max will at least partially compensate for the cyclone slowly edging towards substantially cooler waters and entraining a rather stable appearing cloud field along it's western periphery, and maintain it's identity as a minimal hurricane for another advisory cycle, or whether the diminutive forces will prevail and the expected weakening back to tropical storm transpire.

Another '"Ho Hum" Hurricane in another "Ho Hum" Basin. But keep in mind that the Eastern Pacific Basin is thee *2nd Most Active*, globally speaking, (after the Western Pacific!) and plays an essential role in the global transport of heat from the tropics each and every hurricane season.

Good ol' EastPac Hurricanes. We couldn't do without 'em!

..



Note: This is NOT an official page. It is run by weather hobbyists and should not be used as a replacement for official sources. 
CFHC's main servers are currently located at Hostdime.com in Orlando, FL.
Image Server Network thanks to Mike Potts and Amazon Web Services. If you have static file hosting space that allows dns aliasing contact us to help out! Some Maps Provided by:
Great thanks to all who donated and everyone who uses the site as well. Site designed for 800x600+ resolution
When in doubt, take the word of the National Hurricane Center