Archive for the ‘Tropical Storm’ 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.
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%.
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.
The photo below is actually from a scan of the “full disk” of earth from the GOES-13 satellite. I have cropped the original in order to concentrate upon Tropical Storm Irene. Tropical Storm Jose also shows up in the image; it is very small. To find it look for a small blob of clouds, bright white (about half the width of the state of Florida and located off the Carolinas and next to Bermuda). More information follows after the image.
TWO INDEPENDENT LEFT CLICKS WILL ENLARGE TO THE FULLEST.
TIME OF PHOTO – 2:45 pm Eastern Daylight Time
DATE – Sunday, August 28, 2011
ALTITUDE OF SATELLITE – about 22,300 miles
TIME NEEDED TO SCAN FULL DISK OF EARTH – about 26 minute
LINK TO MORE INFORMATION ON SATELLITE IMAGE – http://noaasis.noaa.gov/NOAASIS/ml/imager.html
THIS IS A TIME-SENSITIVE POSTING SUBMITTED 8-21-2011 AFTER 11 PM EASTERN TIME.
IT IS NOW OUT OF DATE. PLEASE CLICK ON THE BLOG TAB AT THE TOP LEFT OF THIS PAGE AND SCROLL DOWN TO LOOK FOR A MORE RECENT REPORT ON THIS STORM WHICH IS NOW A SERIOUS HURRICANE (posted 8-22-2011 near midnight EDT).
Invest (investigation) 97L (or 97AL) has become Tropical Storm Irene. My concerns for Florida remain and it looks to me as though the east coast is the part of Florida most likely to be influenced by the system. If it does skirt the coast at least that region will be subjected to the left-hand leading quadrant which is almost always less powerful than the right-hand leading quadrant. Based upon my observation of the ECMWF (European Centre for Medium-Range Weather Forecasting) model – it now looks as though South Carolina could very well be the landfall site. Of course many changes can occur over the next few days and much depends upon the movement and strength of a trough dipping down over the Eastern U.S.A. One of my favorite sources, Dr. Jeff Masters wrote yesterday:
“The best model for predicting the timing and strength of such troughs over the past two years has been the ECMWF (European Center model). The European Center does not permit public display of tropical storm positions from their hurricane tracking module of their model, so we are unable to put ECMWF forecasts on our computer model forecast page that plots positions from the other major models. Remember that a 7-day forecast by even our best model will be off by an average of over 700 miles, so it is too early to tell what part of the U.S. might be most at risk from a strike by 97L. This weekend would be a good time to go over your hurricane preparation.”
In the future, if you wish to view the ECMWF model loops go to the right of this page and under the heading of “Tropical Weather” click on the link to Penn. State U. Models Page. Scroll down until you find it.
Here is Jonathan Vigh’s spaghetti chart effort releases at 8 pm Eastern Time, 8-21-2011.
98L intensified to a tropical storm late yesterday. This morning’s graphic below is from the National Hurricane Center for 7 am CDT. Note that the weighted mean forecast path looks a bit like a backwards comma. Following that is Jonathan Vigh’s compilation of computer model tracks in what is referred to often as a spaghetti chart. This one is very busy but a quick glance will give you the general idea.
CLP-5 is a persistence model which, in my opinion, is not likely to represent the true path the storm takes. The BAMS model considers where the storm is likely to travel IF it is moved mainly by shallow (lower level) forces. In my opinion this is unlikely.
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).
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.
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