Archive for the ‘Hurricane models’ Category
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%.
When the European Center for Medium-Range Weather Forecast model is running, here is my favorite site for viewing:
For a lot of different reasons, but mainly because I enjoy the insights of Dr. Jeff Masters in his weather blog, I use WeatherUnderground.com. For future reference, a link to his blog is under the Blogroll category at the right margin of this page. In fact, it’s the first listed.
For the ECMWF Model Run, click on the following link and then follow my instructions exactly: NOTE: YOU MIGHT WANT TO COPY THE INSTRUCTIONS BECAUSE ONCE YOU CLICK ON THE LINK THIS PAGE WILL BE GONE UNLESS YOU CLICK BACK –
- At the upper left of the image, click on the “continent” tab.
- Scroll down the menu on the right margin and click in the box labeled “model data”.
- Another menu dropped down. Click on the “model” arrow and select ECMWF.
- Make sure the “map type” remains on MSL which stands for “mean sea level.”
- Click on the “forecast” arrow and wait patiently for the load.
- After it has loaded fully it should loop. If you want it to stop click on the button at “forecast.”
Though the European Model is not always right (none of them are) it has done the best job for the last two years in situations akin to this one with hurricane Irene. The National Weather Service gives credence to this model though you will not see it indicated on the official spaghetti charts and such. In fact, lately, the NWS official forecasts have been close to that of the ECMWF model runs or, if you please, the ECMWF model runs have been close to the official forecasts of the NWS. To be sure, there will be times when there is little agreement – at which time I expect to lean toward the NWS advisories.
THIS IS A TIME-SENSITIVE POSTING SUBMITTED 8-22-2011 AFTER 11 PM EASTERN TIME.
Hurricane Irene is now of GREAT CONCERN to the Bahamas. Based upon my observation of the ECMWF (European Centre for Medium-Range Weather Forecasting) model – it now looks as though South Carolina or North Carolina could be the landfall site though the statistical mean mid-line continues to “windshield-wiper” to the east.
Here is Jonathan Vigh’s spaghetti chart effort releases at 8 pm Eastern Daylight Time, 8-22-2011. The numbers along the forecast model tracks are “hours from the forecast release time.” OFCL is the designation for “official.” The OFCL is remarkably close to the ECMWF model track which does not show on this graphic. To observe it, go to my “Tropical Weather” links to the right of this page and click on “Penn. State U. Models Page.”
THIS IS NOW A SERIOUS CAT. 2 HURRICANE WITH POTENTIAL FOR STRENGTHENING.
– LEFT CLICK THE GRAPHIC TWICE FOR MAXIMUM ENLARGEMENT –
PLEASE NOTE – THIS IS A TIME-SENSITIVE POSTING
Below is the 11 am (Eastern Daylight Time) cone of uncertainty for hurricane Irene from the National Hurricane Center. Remember, only minor shifts toward the west or east can change the complexion of things drastically. Such changes are common – in fact, some meteorologists refer to resultant realignments of the spreading cone as “windshield wipering.” Left click the image twice for full enlargement.
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.
THIS IS A TIME-SENSITIVE POSTING SUBMITTED 8-20-2011 LATE MORNING EASTERN TIME.
Though there is more than one system out there today, my attention is east of the Lesser Antilles Islands where there is a system that currently has the status of a tropical wave. However, there is an 80% chance that it will become cyclonic within the next 48 hours. The Spaghetti chart below is courtesy of Jonathan Vigh. His efforts to put the model forecasts together produce my favorite renditions. Notice that the islands between its present location and Florida will be effected if this early visual is close to being correct. The storms ability to sustain itself as it moves over land might be touch and go. Frankly, this one really has my attention.
If you left click the image should enlarge – a second left click might enlarge it even further:
Left clicks on this graphic should enlarge it for you.
THIS IS A TIME-SENSITIVE POSTING SUBMITTED 7-30-2011 LATE EVENING.
This is the GFDL model’s forecast for system 91L 126 hours from the 2 PM Eastern time release (today 7-30-2011). Note that it is shown to be north of Eastern Cuba. I calculate the forecast time to be 5.25 days (or 5 days and 6 hours) beyond the release time. That would be Thursday, August 4 at 8 PM Eastern time. This, of course is a forecast loaded with unknowns and fickle variables so one should not consider it a “given.” The GFDL model (Geophysical Fluid Dynamics Laboratory) has impressed me over the last few years. I’m posting this now so that perhaps on Thursday night you might want to check to see how close it is. This posting is not intended to alarm anyone needlessly. If you are in a position where you like to plan ahead and are potentially in the path of tropical systems from the Atlantic and Gulf of Mexico, I advise you to pay close attention to forecasts available to you. It is my opinion that the Weather Channel on television does a great job covering tropical weather and I highly recommend it as a source. Also, on the right hand margin of this page under Miscellaneous/Other you will find a link to the on-line Weather Channel. I also highly recommend the tropical weather blog of Dr. Jeff Masters. Here is a link: http://www.wunderground.com/blog/JeffMasters/article.html
Here is the forecast plot for our first tropical disturbance of the season – released at 1200 Greenwich Time (7AM Eastern Time) June 1, 2011 – the first official day of the season. These are sometimes called spaghetti charts. Please ignore the “straight line” projection into the Gulf which is an extrapolation of movement were there to be no change in course. Already, I’ve detected rightward deflection in its actual track. Two left clicks should fully enlarge this image for you.
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
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.