Archive for the ‘Tropical activity in the Gulf of Mexico’ Category
THIS IS A VERY “TIME-SENSITIVE” REPORT
After viewing the graphic below my concerns for the residents of Tallahassee have increased; of course it goes without saying that my concerns are for everyone who might have to deal with this storm – no matter where they might be located. Mainly, there are three factors involved in my concern for the 7th most highly populated city in Florida and its capital city. One is that there is a strong chance that Hermine will become a hurricane before reaching the Florida coast.
Another: The minimum distance from Gulf of Mexico waters to Tallahassee is about 25 miles. One might consider 25 miles to be an adequate “buffer” to provide friction and thus slow down the winds approaching the city. I think that assumption would be a mistake. Furthermore, when surface or near-surface winds leave the water for land the slight slowing that might occur would tend to cause more air to rise. A similar rising is what causes lake effect snows in certain Great Lakes coastal or near-coastal downwind locations. In the case of humid winds from Hermine possibly decelerating due to friction over the land when approaching Tallahassee, the net effect could very well be more vertical cloud development (due to a greater amount of rising air) than would have occurred otherwise. This phenomenon can intensify thunderstorms, the gusts that spill out from them, and the chaos that can generate tornadoes. The increase in rainfall amounts can be dramatic. So – be careful what you wish for. Flooding is typically a bigger issue than the wind velocities in these cases.
Here is the third cause for my concern: The graphic below from the National Weather Service showing the “cone of uncertainty” (8 PM EST, 8-31-2016) causes me to consider that Tallahassee might very well be under the right-hand leading quadrant of the storm when it makes landfall. The right-hand leading quadrants of tropical cyclonic systems are usually the quadrants with the highest wind velocities, greatest probability for tornadoes, heaviest rains, and in coastal areas the greatest storm surge height. The fact that currently the whole storm is beginning to move faster can increase the danger of the right-hand leading quadrant.
I urge residents of the Tallahassee area to be alert during the approach, passage, and departure of what is now Tropical Storm Hermine. Do not take it lightly just because it is on the low side of the tropical storm wind velocity range at this time (evening of 8-31-2016).
CLICK ON THE IMAGE BELOW TO ENLARGE.
CLICK ON THE IMAGE ABOVE TO ENLARGE.
Compare this to the previous posting which was 24 hours earlier and you will see some change in the tracking model forecasts – which is to be expected.
I have greatest confidence in the TVCA run which is a consensus of 5 other models which have been good performers over the last few years. Generally, the TVCA model is very close to the National Hurricane Center’s “official” track that is the basis for the “uncertainty” cones released to the public. If you are one to pay attention to which models get mentioned or shown in weather reports you have surely heard of the “European model” which is labeled ECMWF. You won’t find it on these spaghetti illustrations; Data from this model is restricted from being redistributed according to international agreement. However, the National Weather Service official track runs very close to being the same as the ECMWF. The BAMM and related models are still useful for long term runs but in this case I think you can pretty much ignore them (the ones that run off toward the west).
Suppose you lived along the Nature Coast of Florida, (e.g. Citrus County) then you might feel that you have nothing to be concerned about because the tracks seem to be shifting northward. But please remember, these tracks are merely forecasting the storm’s center. In most cases the strongest winds are at the right hand, leading quadrant of such storms, which, in this case might cause Citrus County some concerns.
Please be sure to click on the graphic for enlargement.
REMINDER: THIS IS A TIME-SENSITIVE REPORT
As of late this afternoon, 8-29-2016, Invest 99L has strengthened to a tropical depression. For up-to-date information on the system, I recommend Dr. Jeff Masters’ weblog (blog). See link below:
Go to the top of the page and click on News & Blogs.
As of the time of this writing, Dr. Masters expresses reasonable confidence that the system will track in such a way that a landfall will occur somewhere in the Florida coast north of Tampa. I urge all interested persons to pay close attention to Dr. Masters’ postings, the Weather Channel tropical reports, and your local news.
Here is the most recent version from my favorite spaghetti chart source, the National Center for Atmospheric Research in Boulder, Colorado (CLICK ON IMAGE TO ENLARGE):
The graphic above is the Friday, October 4, 2013 10 a.m CDT (advisory #6) from the National Hurricane Center.
Those who follow this web-log know that my primary source of information regarding tropical weather is Dr. Jeff Masters of Weather Underground. His blog can be found by clicking on the “community” tab once you open the following page: http://www.wunderground.com/
It would be a waste of my time and yours for me to try to explain it any better. Here is his verbatim forecast report posted at 1:44 PM GMT on October 04, 2013
Forecast for Karen
Wind shear for the next three days is expected to stay high, around 20 – 30 knots, according to the 8 am EDT SHIPS model forecast. The atmosphere is quite dry over the Western Gulf of Mexico, and this dry air combined with high wind shear will retard development, making only slow intensification possible until landfall. A trough of low pressure and an associated cold front will be moving through Louisiana on Saturday, and the associated upper-level westerly winds will bring higher wind shear near 30 knots and turn Karen more to the northeast as it approaches the coast on Saturday. The higher shear, combined with ocean temperatures that will drop to 28°C, may be able to induce weakening, and NHC has sharply reduced its odds of Karen achieving hurricane strength. The 5 am EDT Friday wind probability forecast from NHC put Karen’s best chance of becoming a hurricane as a 23% chance on Sunday at 2 am EDT. This is down from the 41% odds given in Thursday afternoon’s forecast. Most of the models show Karen intensifying by 5 – 10 mb on Saturday afternoon and evening as the storm nears the coast, as the storm interacts with the trough of low pressure turning it to the northeast. This predicted intensification may be because of stronger upper-level outflow developing (due to diverging winds aloft sucking up more air from the surface.) We don’t have much skill making hurricane intensity forecasts, so I wouldn’t be surprised to see Karen do the opposite of what the models predict, and decay to a weak tropical storm just before landfall, due to strong wind shear. In any case, residents of New Orleans should feel confident that their levee system will easily withstand any storm surge Karen may generate, as rapid intensification of Karen to a Category 3 or stronger hurricane has a only a minuscule probability of occurring (1% chance in the latest NHC forecast.)
Since Karen is expected to make a sharp course change to the northeast near the time it approaches the south coast of Louisiana, the models show a wide range of possible landfall locations. The European and UKMET models are the farthest west, with a landfall occurring west of New Orleans. The GFS model is at the opposite extreme, showing a landfall about 400 miles to the east, near Apalachicola, Florida. NHC is splitting the difference between these extremes, which is a reasonable compromise. Most of Karen’s heavy thunderstorms will be displaced to the east by high wind shear when the storm makes landfall, and there will likely be relatively low rainfall totals of 1 – 3″ to the immediate west of where the center. Much higher rainfall totals of 4 – 8″ can be expected to the east. NHC’s 5 am EDT Friday wind probability forecast shows the highest odds of tropical storm-force winds to be at the tip of the Mississippi River at Buras, Louisiana: 66%. New Orleans, Gulfport, Mobile, and Pensacola have odds ranging from 47% – 51%.
This is the 4 pm EDT advisory for August 30, 2012.
Two left clicks on the image will enlarge it fully.
By the time you see this posting, the forecast graphic for what remains of Isaac (above) will probably be obsolete. Here is where to go to get a comparable update (however, the advisory above might be the last):
In spite of modern technology the tasks of the National Hurricane Center’s forecasters are not easy and I guarantee they burned the midnight oil as this event unfolded. They have so many variables and unknowns to deal with. I think they do a wonderful job.
Where I live, in west-central Florida about 18 miles inland from where the tiny Crystal River flows into the Gulf of Mexico, there are long-term concerns about our fresh water supply. So I had hoped that Isaac would provide just the right amount of water WITHOUT damaging and costly winds and flooding. Like most humans, I want all of the good but none of the bad that can come from Nature’s wonders. At this time, Thursday evening, 8-30-2012, we are still getting some rain directly related to Isaac even though its center is about to move into Arkansas. Hopefully the system will provide needed rain to drought stricken areas in it’s predicted path. My retired-farmer uncle in Indiana indicates that it’s probably too late for the field corn but could be helpful to the soybeans. As I write, flooding and potential flooding in certain areas of Louisiana are creating real headaches there. There are some places claiming to have more water than with Katrina, albeit for different sets of circumstances.
There is so much information available today and I understand the great value of our acquired knowledge about tropical weather since I first began studying it formally (over 50 years ago) but sometimes, I confess, I think fondly of the days when we had little notion of what was going on until much later in a tropical cyclone’s life cycle. Now, it seems that the media devotes an inordinate amount of time telling us about the negatives and potential negatives that are going on all over the world and I can no longer bask in my ignorance as I used to because I haven’t the will-power or inclination to ignore the resources that are available. But, I concede, there are limits to the notion that ignorance is bliss.
I wish you peace, good health, and happiness.
For the last few days, weak tropical storm Debbie has been slowly working her way northward keeping residents of the Gulf coastal states on alert. A huge volume of warm, moist air, some originating all the way from the eastern Pacific (see image above), has been racing northeastward and northward into the storm’s core generating numerous alarming situations conducive to tornadic development. The environment around her has made it very difficult for forecasters to interpret the numerous computer tracking models because there has been little agreement.
At this moment, (6-25-2012) about 2 pm Eastern time, it looks as though she will extend her stay over the Gulf well into the week and eventually work her way eastward to cross Florida and then enter the Atlantic. Where I live in Citrus County, Florida that means we could experience the right-hand leading quadrant of the system. It is that particular quadrant of northern hemisphere tropical systems that usually has the highest wind velocities and the greatest probability for tornadoes and significant sea surges upon the shore. However, I am optimistic that upwelling of cooler water in the Gulf below the storm will further diminish the strength of the storm. Typically, when strong winds skim over warm water and push it aside, that which takes its place is cooler water that “wells up” from below.
There are many factors that can cause a tropical system such as Debby to strengthen and/or weaken – the sea surface temperature changes being but one. However, it is my hope that she does provide us more much-needed rain in a slow and steady manner so that it infiltrates into our groundwater zone instead of traveling as surface runoff. I hope she does decide to take that trip across Florida and that she will be sufficiently mild-mannered to be a great benefit to the region.
Enjoy the satellite view above which shows the extent of Debby’s influence this morning (6-25-2012).
Since I began this site on August 24 2008, it’s been averaging about 12 “hits” per hour. So, I’m not setting the Internet world on fire. I’m sure that many of my “followers” are either friends and neighbors, family, or former students. Of course a number of people reach this site as a consequence of a search term that blends with something I’ve discussed.
This is my first posting in over three months. That might be strange for a site devoted mostly to tropical meteorology but those who know me understand that I devote most of my tropical weather attention to those systems that cause alarm to folks in Central Florida where I now reside.
The six month long official hurricane season whose last day was November 30 was an active one but not for Central Florida. There were some storms in the Atlantic, Caribbean, and Gulf that caused concern but, if you have been following this site you have no doubt noticed that I ignored most of them. I choose to refrain from alarming anyone unnecessarily when I deduce that a storm in question is not likely to bother us. On the other hand, the National Weather Service errs on the side of caution and consequently the “coverage” was vigorous and reports were easily obtained through the media. Though I think that the media does a good job, generally speaking, I am inclined to suspect that they are spectacularizing their reports. There were times when it appeared that a storm would be coming our way here in West-Central Florida but my information and gut-level feelings indicated a very low probability. SPECIAL NOTE: It appears that in using “spectacularizing” I’ve used a word whose acceptance is debatable; it appears to be a mere colloquialism but that fits me well.
This year’s hurricane season was very active! An average northern hemisphere Atlantic/Caribbean/Gulf of Mexico season has 11 named storms, 6 hurricanes, and 2 intense hurricanes.
For the 2011 season there were 19 named storms, 7 hurricanes, and 3 intense hurricanes.
But for the U.S.A. specifically – the season was unusually timid. In his summary of the season, Dr. Jeff Masters (one of my important sources) wrote: “Only two named storms made landfall, Tropical Storm Lee, which hit Louisiana with 60 mph winds, and Hurricane Irene, which hit North Carolina on August 27 with 85 mph winds, and made two additional landfalls in New Jersey and New York the next day.” By the time tropical storm Don reached Texas it had weakened to a tropical depression. There seems to be general agreement that favorable steering currents were the principle reason for our good fortune in the U.S.
I made no entries concerning Irene, in spite of the scare in New York because we were being flooded with media information and for those with cable or satellite, the Weather Channel was right on top of things. Since it wasn’t threatening our Central Florida region I held back in the wake of such comprehensive coverage.
The way our season luckily turned out has indeed caused me some considerable concern over the tendency that we humans have toward complacency. In the 6+ years I’ve lived in Citrus County, Florida there have been no tropical systems of any severe nature but the year before I arrived, 2004, was a busy one with Jeanne, Ivan, Frances, and Charlie. None of those named storms were strong enough to create a county-wide wake-up call. Some people were without power for a few days but the storms did not create events comparable to those which reverberate in our heads for years to follow – like Andrew, for example, which destroyed my home (in Homestead, Florida) in 1992.
I have heard tales of real estate agents in the area boasting that Citrus County possesses some sort of special immunity for whatever reason. I refute that notion absolutely. There is nothing about the environment that affords it the luxury of special protection other than the high sand ridges that minimize storm surge potential for those who live far enough inland from the Gulf. For example, my house sits at an elevation of 55′ above mean sea level so I don’t anticipate storm surge events. However, high water from heavy rains is a distinct possibility.
In any event I urge you who live in my area to NOT ignore the fact that you live in hurricane country. There are so many things about hurricanes that should not be discounted. For example, doubling the wind velocity actually quadruples it’s potential force. So a 60 mph wind has four times the ability to do harm compared to a 30 mph wind. Here is a link to a site which I put together regarding “hurricane misconceptions.” http://ztechzone.net/learningzone/science/science55/hurricanes.html
Coming next: My Christmas Greeting and Reflections.
Thanks to the National Weather Service Hydrometeorological Prediction Center for this graphic.
What you see is a 5 day forecast for the total rainfall in inches between 8 AM Eastern Daylight Time Sunday and 8 AM EDT on Friday . The feared 15″ of rain in the New Orleans area predicted 36 hours earlier seems highly unlikely. For ease in reading, left click the image two times independently for full enlargement.
Thanks to the National Weather Service Hydrometeorological Prediction Center for this graphic.
What you see is a prediction for the total rainfall in inches between 8 AM Eastern Daylight Time Saturday and 8 AM EDT on Thursday (in other words – a 5 day total forecast). Already, since this was released, the feared 15″ of rain in the New Orleans area seems highly unlikely due to dry air from Texas being drawn into the system. For ease in reading, left click the image two times independently for full enlargement.
Shortly before noon Eastern Daylight Time today (8-30-2011) Dr. Jeff Masters published this statement:
“Gulf of Mexico development possible late this week”
“Several of our best computer models for predicting formation of tropical cyclones, the GFS and ECMWF, are predicting that an upper level pressure interacting with a tropical wave now over the the Western Caribbean could combine to spawn a tropical depression in the Gulf of Mexico late this week or early next week. The formation location is likely to be off the coast of Louisiana or Texas, but the track of the system is hard to predict at this point.” (end quote) –
Though this is far too early to tell, here is a six day look into the ECMWF model’s “take” on our tropical weather. It was released at 8 pm EDT, 8-29-2011 and projects out six days (144 hours).
Notice, in addition to the system in the Gulf of Mexico, the position northeast of Puerto Rico of what is currently Tropical Storm Katia. Some are predicting that she will be of hurricane strength by the time 6 days pass.
The error 6 days out can be enormous so take this for what it’s worth. I recommend your being mindful that the ECMWF has been doing well for the last couple of years. For instructions on viewing the model in animated form on WeatherUnderground.com, please use the following link: https://cloudman23.wordpress.com/2011/08/25/ecmwf-model-run-the-european-model/
NOTE: ECMWF = European Center for Medium -Range Weather Forecast