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Posted at 2:15 PM ET, 10/25/2010

Richard's troublesome tropical journey

By Greg Postel

* Showery: Full Forecast | Arctic ice loss to enhance D.C. snow? *

td-richard-102510.jpg
Visible image of Tropical Depression Richard over the Yucatan Peninsula from 1:25 p.m. Monday (today). Source: NASA

After battering Belize with heavy rains and strong winds (measured to around 60 mph), Richard - now a tropical depression - is winding down, with little deep convection remaining. Although Richard's remnants may re-emerge in the Gulf of Mexico after crossing the Yucatan Peninsula, strong upper level winds are likely to impede any redevelopment.

Richard's life as a tropical cyclone has been a difficult one. After an extremely slow intensification process, it finally reached hurricane strength Sunday morning (see this cool radar loop of Richard making landfall). Fueled by 85-degree ocean water, amidst weakening vertical wind shear (changing of the wind with height) and a progressively humidifying environment, Richard's maximum sustained winds peaked at 90 mph just prior to its landfall roughly 20 miles south of Belize City late Sunday.

Since its inception late on the October 20, Richard battled a very dry and windy environment. Data from aircraft observing the storm late last week revealed exceedingly low dew points -more typical of fall-like conditions in the Northeast- throughout thick layers of the atmosphere working their way toward the core of the circulation. Only in the final few hours before landfall was it able to conquer these formidable obstacles, enough so to attain hurricane status.

Yet formidable is not a strong enough adjective to describe the conditions Richard had to overcome.

Dry and windy environments can be lethal barriers to a tropical cyclone's maturation. Once dry air gets inside a storm, as it apparently did to some degree with Richard for much of its lifetime, large-scale downdrafts begin to develop in the same region that requires upward motion and nearly saturated conditions to survive. These relatively cool sinking motions, similar to the gust fronts we observe with the passage of thunderstorms in our area, act to reverse the counter-clockwise hurricane swirl as they spread outward upon nearing the surface.

Even in the absence of the destructive forces of wind shear, which can dismantle and tear apart the plume of heat in the core that powers the circulation, dry air intrusions can assassinate a hurricane.

Tropical cyclones, and in particular hurricanes, are markedly unlike the thunderstorm complexes we experience in the mid-latitudes. Their existence largely requires weak wind patterns (instead of highly sheared flows), humid conditions, and little if any of the kind of "instability" (cool temperatures aloft) that our neighborhood storms thrive on.

By Greg Postel  | October 25, 2010; 2:15 PM ET
Categories:  Tropical Weather  
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Comments

Richard hurricane battered the small Central American country of Belize, sending thousands to shelters and forcing the evacuation of tourists to the outer islands, before weakening to a tropical depression yesterday morning.
Belize News http://www.thenews12.com/belize-news-142/

Posted by: parikhan | October 25, 2010 2:41 PM | Report abuse

Just added to this post a cool radar of Richard making landfall: http://wapo.st/dy5uRH

Posted by: Jason-CapitalWeatherGang | October 25, 2010 2:59 PM | Report abuse

Considering the difficulty it had prior to yesterday it was intensifying quite nicely at landfall. Good thing it ran out of time. There have been a few storms this year that have strengthened into landfall, which seems somewhat unusual in my yrs of tropical watching. It seems more common to get a storm to peak over water than cruise in either holding its own or weakening.

Posted by: Ian-CapitalWeatherGang | October 25, 2010 3:17 PM | Report abuse

Hi Ian-CapitalWeatherGang

You're right ... it's been a strange year that way, hasn't it. There will be some research done, I'm sure, on why the tracks and genesis locations were the way they were.


greg

Posted by: gregpostel | October 25, 2010 3:44 PM | Report abuse

Greg, was the upper-level high pressure smaller than average over Belize (and close-by areas) - because I notice that on most sides of this calm bubble, the winds are fierce. Perhaps the sheer environment at the high's perimeter is related to the time of the year?

Posted by: Camden-CapitalWeatherGang | October 25, 2010 4:36 PM | Report abuse

I can remember when Hurricane Hattie hit Belize [then British Honduras] back in or around 1961. Hattie was probably the worst hurricane in recent memory to strike this region.

Posted by: Bombo47jea | October 25, 2010 11:51 PM | Report abuse

I know we are nearing the tail end of hurricane season, I'm interested to know if you think there's any chances for anything tropical to develop in the Southern Caribbean in the next 10 days or so. I'm going on a cruise out of San Juan which ends up down in Trinidad before we sail back to San Juan. I'm hoping that I won't have a second vacation spoiled by tropical weather (we were evacuated from the OBX for Earl).

Posted by: ana_b | October 26, 2010 8:05 AM | Report abuse

Hi ana_b,

The odds are slim, especially with high winds aloft expected over (at least the Northern) Caribbean late next week. However, if conditions unexpectedly become favorable for development, CWG will cover it closely. Happy Travels.

greg

Posted by: gregpostel | October 26, 2010 3:17 PM | Report abuse

Hi Camden-CapitalWeatherGang

not really ... the notion that a high pressure system aloft helps a hurricane develop really only applies at the storm-scale. That being said, the conditions nearby upper highs are often much more friendly than those close to upper lows. The problem with Richard was, as you indicate, a strong subtropical jet and desert-like conditions aloft.

greg

Posted by: gregpostel | October 26, 2010 3:25 PM | Report abuse

Thanks Greg!

Posted by: ana_b | October 26, 2010 9:03 PM | Report abuse

The comments to this entry are closed.

 
 
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