24 November 2008

Disturbance brewing off Panama coast...

With less than a week remaining in the official Atlantic hurricane season, an area of persistent convection has been festering in the extreme southern Caribbean Sea, just off the northern Panama coast.  It's been there for well over a week now, stationary, yet growing in size and ever so slowly getting better organized.

An active microwave scatterometer, a satellite-based instrument which indirectly measures surface wind speed and direction over water, detected reliable winds in the disturbance up to 35kts this morning, but more commonly in the 20-25kt range.  There is moderate southwesterly vertical shear over the system, and SSTs are around 29C.  There is a 1007mb surface Low embedded in the disturbance.  The forecast is extremely difficult, as is usually the case with minimal steering flow.  Some models keep it basically stationary for the next few days, while others give it a slow nudge off to the north or northeast.  If it remains over water, it certainly has the potential to continue organizing.  However, given the motion (or lack thereof), there is time to monitor it.  The biggest immediate threat is flooding rains in Panama, Costa Rica, and Nicaragua.  In the off-chance this gets named, the next name on the list is Rene.

The season has been an active one, with 16 named storms and 8 hurricanes, 5 of which became major hurricanes (CAT3+).  Although there were no CAT5 storms this year, there was a major hurricane in every month from July through November, which was a first.  In July, Bertha reached 105kts, Gustav reached 130kts in August, Ike reached 125kts in September, Omar reached 110kts in October, and Paloma reached 125kts in November.
If one considers an "average" season based on 1950-2000 climatological values of the number of named storms, hurricanes, and intense hurricanes, as well as the longevities of each, and defines that to be 100% of normal activity, this season was 165% of average activity.  It was similar in total activity to 1998's season.

Please visit my tropical Atlantic headquarters.

08 November 2008

Paloma becomes season's 5th major hurricane...

At 03Z last night, Paloma was upgraded to a Category 3 hurricane, making it the 5th major hurricane of the season.  What makes this feat remarkable (unprecedented in fact), is that all 5 major hurricanes occurred in 5 separate months!  Bertha was in July, Gustav in August, Ike in September, Omar in October, and now Paloma in November.  Paloma is also now tied for the 2nd strongest November hurricane on record (Michelle has first at 135kts, and Lenny is tied for second at 120kts).

At 15Z today, Paloma's intensity was 120kts and 943mb, making it a CAT4 storm now.  A long radar loop from Camaguey, Cuba can be found at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/paloma08/Paloma_07-09Nov08_cmw.gif

Shortly after making landfall on Cuba, the storm is forecast to rapidly fall apart, due to a combined effect of land and drastically increasing vertical shear.  However, unfortunate for Cuba is that it should make landfall as a major hurricane, delivering very powerful winds, flooding rains, and a 20' storm surge.

Please visit my tropical Atlantic headquarters.

07 November 2008

Paloma becomes season's 8th hurricane...

As expected, the storm continued to strengthen, and late last night was upgraded to Hurricane Paloma.  As of 15Z today, the intensity is 75kts with a minimum central pressure of 979mb.  It is crawling north at 6kts toward central Cuba.  The satellite presentation is becoming very impressive and it could become the season's 5th major hurricane.

The last major hurricane in November was Michelle 2001 (reached 120kts on Nov 4th as it neared central Cuba... VERY similar to Paloma). The last storm that FORMED in November and became a major hurricane was Lenny 1999, which reached a peak intensity of 135kts on November 17th.  So November is no stranger to very intense hurricanes!

Paloma is forecast to intensify to a CAT3 hurricane before it hits central Cuba this weekend.  A major consideration however, is increasing vertical shear in about a day... so if it will reach CAT3 intensity, it needs to do so quickly. There will (hopefully) be a coherent radar loop from Camaguey at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/paloma08/Paloma_06Nov08_cmw.gif but so far, there have been substantial server glitches preventing reliable data transfers.  The Cuban meteorological service is looking into it though.

Please visit my tropical Atlantic headquarters.

06 November 2008

Paloma finally forms in southwest Caribbean...

After 1.5 weeks of festering convection off the Nicaraguan coast, TD17 formed on Wednesday, and has quickly gotten better organized.  It was upgraded to TS Paloma, the 16th named storm of the season, early Thursday.  As of 15Z, Paloma's intensity was 40kts and 998mb, but is rapidly intensifying, and could be nearly a hurricane by the next advisory.  It has persistent deep convection organized into an eyewall, and the eye is clearing out as I type this.  It's located just off the corner of Honduras and Nicaragua, and crawling north toward western Cuba.  However, it is expected to gradually turn more NE and cross central Cuba late this weekend as a powerful hurricane.  This has unfortunately been a devastating year for Cuba... Fay, Gustav, Ike, and now Paloma.

You will find an updating radar loop of Paloma from Camaguey, Cuba at http://einstein.atmos.colostate.edu/~mcnoldy/tropics/paloma08/Paloma_06Nov08_cmw.gif

An aircraft is en route to more accurately determine the intensity, but it seems to be on a quick path to becoming the season's 8th hurricane.  The ocean under the storm is deep and warm, and the vertical wind shear is minimal.  This is a climatologically favored time of year for these western Caribbean storms that head northeast and cross over Cuba.

Please visit my tropical Atlantic headquarters.