Archive for September, 2010|Monthly archive page
Having a daughter and two grandsons living not far south of Jacksonville, I have been somewhat concerned about the current tropical weather. A few days ago the GFDL model showed the Jacksonville area getting tropical storm winds from Nicole but that is no longer in the forecast. However, interestingly, this morning’s GFDL model shows another storm moving along almost the same track as Nicole off to the east of Miami 5 days from now! We shall see.
In the U.S. Navy plot above, the two nearly identical figures that look like oddly altered letter D’s represent the 34 knot line. In other words, sustained wind velocities outside of those figures are expected to be less than 34 knots (nautical miles per hour).
Part of the image above was done in 2007 and part in 2008. I copied this from Google Earth this morning to give you an idea of the size and configuration of the beautiful British Overseas Territory of Bermuda. Notice the 5 mile long scale at the lower left. Latitude and longitude are also shown at the bottom margin. This view is from an altitude of over 17 miles. I recommend Google Earth for those of you who might be interested in more detail which is readily available. There is a free version available. With practice you can have great fun exploring the earth.
http://www.google.com/earth/explore/products/desktop.html The free version of Google Earth 5 is the one that appears first on the page.
Yesterday Hurricane Hunter aircraft crews found that the inner 23-mile wide eyewall had collapsed during what seemed like a fairly typical eyewall replacement cycle. A very large 92-mile wide eye was the result and, and as usually happens in such events the hurricane weakened. Currently hurricane force winds are now spread out over a larger area but Igor is “down” to a category 1 hurricane. Much of the big eye wall has collapsed and though that is good news, Bermuda is still in for some strong winds of long duration – and intensification is still a possibility. In any event, there is likely to be considerable damage to beaches and some structures. I am under the impression that residents of Bermuda are “hurricane savvy” and probably better prepared than those who live along Eastern coastal U.S. A.
According to a 9-17-2010 posting on Air-Worldwide.com, “Homes in Bermuda are typically one or two stories and constructed of ‘Bermuda Stone,’ a locally quarried limestone, or of concrete blocks. Roofs are commonly made of limestone slate tiles cemented together. Commercial buildings, typically of reinforced concrete construction, rarely exceed six stories. In both residential and commercial buildings, window openings are generally small and window shutters are common. These features make Bermuda’s building stock quite resistant to winds, and homes are designed to withstand sustained winds of 110 mph and gusts of up to 150 mph.”
LEFT CLICK ON THE IMAGE ABOVE
AND THEN WAIT PATIENTLY FOR AN ANIMATION.
I RECOMMEND YOU READ THE INTRO. BELOW FIRST.
I’m posting this on the afternoon of Wednesday, 9-15-2010. What you will be looking at as you view the animation above is, to my mind, fantastic. I would have loved to have had such a tool to use in the college classroom when I was a full-time meteorology professor. Even though this is jerky, it gives a wonderful view of things which I and my students could only imagine back before my retirement from the profession. The stream will quickly get to mid-day (of Monday, Sept. 13) and the sun will quickly reach the western horizon marking sunset. If you focus upon the eye in the afternoon you will see the shadow created by the wall cloud’s western margin as it creeps eastward. Also watch the boiling cumuliform tops in various places. I was fascinated by the way the clouds moved within the eye of the storm as it rotated. ENJOY!
SPECIAL NOTE: For those of you who understand hurricane circulation in more detail than most, notice the lower level clouds converging cyclonically (counterclockwise in the Northern Hemisphere) and look hard enough at the more diffuse high clouds and you will detect the anticyclonic divergence (clockwise in the Northern Hemisphere). The latter is easiest to see on the west side of the storm where you can envision the feathered cirrus moving toward the north or northwest. If they seem to you to be standing still that is because the ice crystals are sublimating at the leading edges of the clusters (turning from solid to gas) whereas deposition (gas to solid) is occurring at the trailing edges.
Watch the digital clock at the bottom margin of the image and you will note that after the initial spurt of one frame per 15 minutes, it settles down to a nicer one frame per minute.
* * * * * * *
This hurricane is a very strong one and potentially dangerous – particularly for the 65,000 or so people in Bermuda. Let’s hope that they escape unharmed. I’m hoping that Igor takes a surprisingly sharper right turn than anticipated in order to spare those fine people.
However, no matter the outcome, it’s difficult not to be in awe of this beautiful beast. It’s also important, I think, to recognize that there are some good things about this storm especially when coupled with the impending effects of Julia which is positioned further to the east. A certain amount of energy MUST be transformed over the Atlantic in order that it not be all released at once. An analogy: It’s better to have one tiny earthquake per year along an active fault than wait for 100 years before all of that stored energy is released as one gigantic earthquake.
The fact that Igor and Julia are both releasing huge amounts of latent heat into the atmosphere is good – particularly when that is happening over relatively uninhabited places. Generally such long fetches over such long periods of time will move warm, tropical water such that it is replaced from below by cooler upwelling water. That is good because the next system to move by is less likely to have as much oceanic heat to stoke it.
At the time I’m writing this (about 5 pm EDT, 9-15-2010) Igor is a category 4 hurricane and Julia is a category 3. However, not many hours ago Julia was also a 4 and she might intensify to that category again. According to my sources, this is only the second time in history that we have had two category 4 storms in the Atlantic at the same time.
Dr. Jeff Masters of WeatherUnderground.com wrote of that fact in his weblog today. Rather than mimic what he has said, I’m placing his well-written statement below in blue.
T. Ansel Toney
e-mail = ProfToney@gmail.com
“The Atlantic hurricane season of 2010 kicked into high gear this morning, with the landfall of Tropical Storm Karl in Mexico, and the simultaneous presence of two Category 4 hurricanes in the Atlantic, Igor and Julia. Tropical Storm Karl’s formation yesterday marked the fifth earliest date that an eleventh named storm of the season has formed. The only years more active this early in the season were 2005, 1995, 1936 and 1933. This morning’s unexpected intensification of Hurricane Julia into a Category 4 storm with 135 mph winds has set a new record–Julia is now the strongest hurricane on record so far east. When one considers that earlier this year, Hurricane Earl became the fourth strongest hurricane so far north, it appears that this year’s record SSTs have significantly expanded the area over which major hurricanes can exist over the Atlantic. This morning is just the second time in recorded history that two simultaneous Category 4 or stronger storms have occurred in the Atlantic. The only other occurrence was on 06 UTC September 16, 1926, when the Great Miami Hurricane and Hurricane Four were both Category 4 storms for a six-hour period. The were also two years, 1999 and 1958, when we missed having two simultaneous Category 4 hurricanes by six hours. Julia’s ascension to Category 4 status makes it the 4th Category 4 storm of the year. Only two other seasons have had as many as five Category 4 or stronger storms (2005 and 1999), so 2010 ranks in 3rd place in this statistic. This year is also the earliest a fourth Category 4 or stronger storm has formed (though the fourth Category 4 of 1999, Hurricane Gert, formed just 3 hours later on today’s date in 1999.) We’ve also had four Cat 4+ storms in just twenty days, which beats the previous record for shortest time span for four Cat 4+ storms to appear. The previous record was 1999, 24 days (thanks to Phil Klozbach of CSU for this stat.)”
Dear Tropical Weather Watchers,
I cropped the image above from a full disk image. It was taken from the 4:45 pm (EDT) transmission of the GOES-13 weather satellite which is positioned at an altitude of 22,300 miles above the Equator at longitude 75 West. At that altitude it orbits earth with the same period of revolution as the earth’s spin on its axis. Therefore it stays over the same point (though it can be moved either east or west if desired). By contrast, the International Space Station orbits at only 236 miles above the surface and the U.S. Shuttle crafts fly lower than that sometimes but have also gone higher – up to 365 miles or so above the surface to the Hubble Telescope. It should be noted that neither the Space Station, the Shuttles, nor the Hubble are on equatorial orbits like the GOES Weather Satellites but instead they are at an inclination of 51.6 degrees to the equator.
In this image provided the sun had gone well past zenith and therefore you can see the bright eastern side of Igor’s eye wall. It’s a very impressive storm.
More information about the three tropical weather systems depicted here can be found at the following site:
Click on each for printed reports.
Some computer models are not developing this tropical disturbance at all – and the ones that are, as you can see, have it all over the place. We must wait and see for there is very little agreement here. Obviously, it should not be forgotten – not yet.
Igor is still out there and the model forecast tracks have not changed much from yesterday’s. I recommend the National Hurricane Center’s site for the latest at: http://www.nhc.noaa.gov/index.shtml
Here is the 8 am EDT forecast track for Tropical Storm Igor.
Here is a recent satellite image showing Hermine and the remnants of Gaston.
NOTE: the CDO to which the following report refers to is “Central Dense Overcast.”
THE FOLLOWING REPORT WAS TAKEN VERBATIM FROM THE NATIONAL HURRICANE CENTER’S WEBSITE. IT WAS RELEASED AT 10 PM EASTERN DAYLIGHT TIME, 9-9-2010
000WTNT45 KNHC 070235TCDAT5TROPICAL STORM HERMINE DISCUSSION NUMBER 5NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL102010
1000 PM CDT MON SEP 06 2010
THE CENTER OF HERMINE MADE LANDFALL ON THE COAST OF NORTHEAST MEXICOAROUND 0130 UTC. PRIOR TO LANDFALL…SATELLITE DATA SHOWED THEFORMATION OF A CDO-LIKE FEATURE…WITH A LARGE AREA OF CONVECTIONALSO LOCATED NORTHEAST OF THE CENTER. THE LAST AIRCRAFT FIX AT 2333UTC SHOWED A PEAK 850-MB WIND OF 61 KT…WITH SFMR VALUES UP TO 56KT. DATA FROM THE BROWNSVILLE WSR-88D RADAR EARLIER INDICATED PEAKWINDS OF ABOUT 75 KT AT 4000 FT. THESE DATA SUGGEST THE LANDFALLINTENSITY WAS ABOUT 55 KT. SINCE LANDFALL…THE VELOCITIES FROM THEBROWNSVILLE RADAR HAVE DECREASED…AND THE INITIAL WIND SPEED ISLOWERED TO 50 KT. AS HERMINE WEAKENS…THE BIGGEST THREAT WILLSHIFT TO FLASH FLOODING FROM HEAVY RAINS AS THE CYCLONE MOVES INTO TEXAS.
THE INITIAL MOTION IS 330/12. THERE IS NO CHANGE TO THE FORECASTREASONING FROM THE PREVIOUS PACKAGE. HERMINE SHOULD MOVENORTH-NORTHWESTWARD AND THEN NORTHWARD AROUND THE WESTERN PERIPHERYOF A RIDGE OVER THE SOUTHEASTERN UNITED STATES FOR THE NEXT DAY ORSO. THEREAFTER…THE REMNANTS OF HERMINE WILL LIKELY TURN TOWARDTHE NORTHEAST AND EAST OVER THE CENTRAL UNITED STATES IN A COUPLEOF DAYS AS THE CYCLONE RIDES AROUND THE NORTHERN SIDE OF THATRIDGE. THE NHC FORECAST IS SHIFTED SLIGHTLY TO THE EAST IN GOODAGREEMENT WITH THE GFS AND ECMWF MODELS.
RELEASED 8 AM EDT TODAY 9-6-2010
SHOWERS AND THUNDERSTORMS HAVE BECOME LESS ORGANIZED DURING THE PAST FEW HOURS IN ASSOCIATION WITH THE REMNANT LOW OF GASTON...LOCATED ABOUT 400 MILES EAST OF THE NORTHERN LEEWARD ISLANDS. ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BECOME MORE CONDUCIVE FOR DEVELOPMENT OVER THE NEXT DAY OR SO AS THE SYSTEM MOVES WESTWARD AT ABOUT 15 MPH. THERE IS A HIGH CHANCE...70 PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE AGAIN DURING THE NEXT 48 HOURS. HEAVY RAINS AND GUSTY WINDS SHOULD BEGIN TO AFFECT PORTIONS OF THE LEEWARD ISLANDS LATER TODAY AND TONIGHT...AND INTERESTS IN THOSE ISLANDS SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.
The remains of Gaston don’t look like much this morning on the satellite imagery, but as you just read, there is a strong chance that it will redevelop into a tropical cyclonic system soon. It is already cyclonic (loop imagery has been showing rotation for several hours now) but Weather Service experts are not ready to declare it a tropical depression on the basis of the very limited amount of current thunderstorm development. But that is likely to change soon. My feeling is that since it is of tropical origin and it is rotating – it should be designated a depression at this moment – but what do I know? LOL
Unfortunately, as you can see, the models seem to favor its moving south of Hispaniola and Cuba. This means, of course, that it’s bound for the Gulf of Mexico unless a decidedly sharp turn to the north were to occur before entering that body. As usual, I recommend that you ignore the CLP5 model. The bottom line is that former Gaston deserves our attention.