Archive for the ‘Hurricane models’ Category

IRMA POSTING – PLUS

– click mouse twice for full enlargement of this image –

 

 

FIRST ENTRY IN MORE THAN A YEAR – 9-6-2017

I apologize to those few of you who have been consulting this weblog. My last posting was August 31, 2016. I’m still going strong and my interest has not waned. I’m still in the learning mode and intend to stay there. But it’s been a long time since I retired from teaching full-time college geosciences in 2003 and a lot has changed. I continued adjunct teaching after I retired but then moved away from South Florida in 2005. From 2006 into 2013 I taught 14 short-term courses at the College of Central Florida. Interest in this weblog seems to have diminished since I stopped formal teaching. However, when I checked this site this morning I saw that it has gotten tons of hits over the last few days, probably due to hurricane Irma. Prior to this current event almost all geoscience questions and observations that have come my way have been from a few family members, a few neighbors, and one buddy at church. It is very rare for me to hear from former students.

In-so-far as weather reporting is concerned, the information available to the public has blossomed since I retired and, for the most part, its quality has improved to the point that there is little if anything I can add (beyond basics). Many of my notions concerning tropical weather events fall into the category of hunches or intuition. I don’t believe that my 37 years of teaching meteorology full-time gives me license to clutter minds with my ideas unless I’m honest about them. Instead, in the comments below about Irma, I will share the four tropical weather resources I consult most often.

I am planning a change of theme and/or purpose for this site soon – more in the realm of discovery, opinions, observations, analyses, experiences, and perhaps some attempts at humor. The “About” page for this site was updated earlier today and if you wish to contact me, you will find my address there.

 

 

MY INPUT ON OUR CURRENT TROPICAL WEATHER

WHICH IS BEING DOMINATED BY HURRICANE IRMA.

My four primary resources are:

  1. Dr. Jeff Masters’ weblog (blog) at WeatherUnderground.com. It can be found here: https://wwwwunderground.com/cat6

  2. The Weather Channel on television and on-line – including apps. There are things about the Weather Channel presentations I don’t like. Nevertheless I appreciate the convenience and their efforts.

  3. The National Hurricane Center. I go to this site to get a grip on what is going on in their world. I consider that they might tend to err on the side of caution, subconsciously at the very least. What an awesome responsibility they have. Http://www.nhc.noaa.gov/

  4. The ECMWF Model – commonly referred to as the European Model.

I rely upon it heavily because of it’s premier reputation due to its accuracy over the last few years. It has done well for the “Irma type” storms. To be sure, I don’t ignore the other models. The following paragraph is for those who have been trying to understand that model.

You are likely to have heard many references to the European Model. I admit it is confusing. For example, here is a quote from Dr. Jeff Masters. “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 other major models.” Thus, even though on television or on-line you may see comparisons of the European Model to the myriad other models, you might have noticed that it’s not included in the spaghetti charts that show models from multiple sources. What you will see is either the European “operational” model track or the European Ensemble (a spaghetti graphic). For that spaghetti ensemble the operational model is re-run at a lower resolution (called the control run) and this is then repeated 50 times, each with slightly different starting conditions.

I get my favorite animated European model track from Penn State’s Department of Meteorology at http://mp1.met.psu.edu/~fxg1/ECMWF0.5_0z/ecmwfloop.html

Please note that this link is time-sensitive.

Of the four charts, I focus upon the one on the upper right as I scroll through f24 through f240 ( which means “24 hours into the future” through “240 hours into the future”).

You might fry your brain with the time signatures on the bottom – depending upon your comfort level with time at the prime meridian (Universal, Greenwich, Zulu) and your knowledge of Victor time.

 

THE CORIOLIS EFFECT

I’ve been thinking all day long about the Coriolis Effect as it relates to Irma. If you are my former student you might recall that the steering currents at high altitude are, in part, a function of the Coriolis Effect (the Penn State chart on the upper left) and I’ll bet you remember that the counterclockwise circulation of Irma is due to the Coriolis Effect. If you’re still sharp on the subject you might also remember that the outflow at the top of the storm is likely to be clockwise for the same reason – the Coriolis Effect. I know that sounds like a contradiction to those of you who are unfamiliar with this subject. If you are interested in the Coriolis Effect go here:

https://cloudman23.wordpress.com/2008/10/02/the-coriolis-effect-in-the-real-world-a-tutorial-part-1/

and here:

https://cloudman23.wordpress.com/2008/10/07/the-coriolis-effect-in-the-real-world-a-tutorial-part-2-cyclones-anticyclones/

 

MY NOTIONS TODAY ABOUT IRMA

Here is my zinger that comes from the “gut level” and is therefore probably not deserving of any classification other than “pure speculation.” (That’s the honesty I referred to in the second paragraph of this blog).

I am expecting (or is it hoping and praying for?) slightly more turning to the right than the experts are indicating. The itty-bitty turn last night was encouraging to me. I keep telling myself that the hurricane is a separate entity of its own and that the Coriolis Effect is influencing it’s path independent of the steering currents and the rotational motion. That path is the consequence of what is referred to as translational motion. Furthermore, the further north the storm gets, the stronger the Coriolis Effect will be. The Coriolis Effect is zero at the equator and increases to 100% at the poles. Maybe I’m just overly excited about last night’s noticeable veering of Irma’s path. Perhaps this is merely a good example of wishful thinking. We’ll see.

 

FOR CITRUS COUNTY, FLORIDA

Finally, for those of you who live in my county of Florida, Citrus, you might be interested in this August 2014 posting about hurricanes.

https://cloudman23.wordpress.com/2014/08/22/citrus-county-florida-and-hurricanes/

 

 

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Karen Is A Gulf Coast Concern

Karen– 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%.

ECMWF MODEL RUN – THE EUROPEAN MODEL

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 –

 

http://www.wunderground.com/wundermap/

  1. At the upper left of the image, click on the “continent” tab.
  2. Scroll down the menu on the right margin and click in the box labeled “model data”.
  3. Another menu dropped down. Click on the “model” arrow and select ECMWF.
  4. Make sure the “map type” remains on MSL which stands for “mean sea level.”
  5. Click on the “forecast” arrow and wait patiently for the load.
  6. 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.

IRENE – SPAGHETTI CHART – 8-22-2011 NEAR MIDNIGHT EDT

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.

Graphic courtesy of Jonathan Vigh, Colorado State University

– LEFT CLICK THE GRAPHIC TWICE FOR MAXIMUM ENLARGEMENT –

Irene Is Now a Hurricane – 8-22-2011

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.

LEFT CLICK TWICE FOR FULL ENLARGEMENT

IRENE – 8-21-2011 SPAGHETTI CHART

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.

TWO LEFT CLICKS WILL ENLARGE THIS FULLY FOR YOU

97AL – Tropical System May Become a Threat to Florida

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:

TROPICAL SYSTEM 91L. A 5 DAY PLUS FORECAST BY THE GFDL MODEL.

THANKS TO PENN STATE UNIVERSITY DEPARTMENT OF METEOROLOGY FOR THIS GRAPHIC.

 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

Forecast Model Plots for Our First Tropical System of the Season – 2011

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.

Click on Image to Enlarge

Tropical Disturbance 92L Is A Problem – Not Much Model Agreement

THANKS TO JONATHAN VIGH OF COLORADO STATE U. FOR THIS GRAPHIC

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