IRMA POSTING – PLUS

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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/

 

 

Karen Is A Gulf Coast Concern

– 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.

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

Atlantic Hurricane Season – Please Be Alert – 8-19-2010

We are entering the peak of the Atlantic hurricane season.  If you have not been influence by tropical activity thus far this year you might be under the impression that it’s an inactive season.  That would not be true.  Statistically, it has been about average to date. Though we cannot “plan the future” I feel strongly that we should plan “FOR” certain eventualities in the future.  I urge you to be prepared and alert in the event that a tropical system comes your way.

The following statement in “blue” was taken Verbatim Thursday morning (8-19-2010) from the Dr. Jeff Masters web-log found at http://www.wunderground.com/tropical/.

“The GFS, NOGAPS, and ECMWF models continue to predict that a tropical storm will form between Africa and the Lesser Antilles Islands sometime in the period 3 – 6 days from now. There is an area of disturbed weather south of the Cape Verdes Islands, but there is no obvious organization to the cloud pattern. Wind shear is a hefty 20 – 30 knots in the region, and the disturbance is a 1 – 2 day journey away from reaching a lower shear area where development can occur. Preliminary indications are that if a storm did develop in this region, it would track west-northwest and pass well to the northeast of the Lesser Antilles Islands 7 – 8 days from now. However, 7-day forecasts of a storm that hasn’t even formed yet are not to be trusted.”

I have taken the liberty of trimming the latest full disc color satellite image down to a manageable size where you can still easily find Florida and thus look across the Atlantic to see the area of disturbed weather off Africa to which Dr. Masters refers. Two independent left clicks on this image will enlarge it fully. This image was taken from a distance over three earth diameters away from the surface yet there is considerable detail.  I hope you enjoy it.

TROPICAL STORM COLIN – 8-3-2010

The most recent Atlantic disturbance has evolved into a tropical storm.  Here is Colin’s general forecast track released at 5 A.M. Eastern Daylight Time on Tuesday, August 3, 2010. Left click on the image to enlarge.

Bonnie Continues As Predicted

Graphic courtesy of Hurricane Alley - for 2 pm EDT 7-23-2010

In an attempt to provide you variety in the storm track presentations, I’ve used Hurricane Alley’s version for this afternoon.  Here is a link to their home page;  http://www.hurricanealley.net/

One of my primary sources, Dr. Jeff Masters of Weather Underground posted the following at 4:40 pm EDT today (7-23-2010):

“The projected track will take Bonnie over the oil spill region, and the storm’s strong east to southeasterly winds will begin to affect the oil slick on Saturday morning. Assuming Bonnie doesn’t dissipate over the next day, the storm’s winds, coupled with a likely storm surge of 2 – 4 feet, will drive oil into a substantial area of the Louisiana marshlands. However, the current NHC forecast has Bonnie making landfall in Louisiana near 9pm CDT Saturday night. According to the latest tide information, this will be near the time of low tide. This will result in much less oil entering the Louisiana marshlands than occurred during Hurricane Alex in June. That storm brought a storm surge of 2 – 4 feet and sustained winds of 20 – 30 mph that lasted for several days, including several high tide cycles.”

A reference to Dr. Masters with a photograph is in the following outdated post from 2009:  https://cloudman23.wordpress.com/2009/11/08/ida-forecast-11-8-09/

Here is a link to the Weather Underground Tropical Page:  http://www.wunderground.com/tropical/

TO GET TO CLOUDMAN23’s HOME PAGE CLICK ON THE “BLOG” TAG ABOVE.

IDA FORECAST – 11-8-09

Some of the information on this site is published close to “real-time”  particularly as it applies to tropical weather.  But it is important to remember that the only “official” source of information is the National Hurricane Center. Decisions concerning life or death, property, and such should not be made based solely on the information found on this site or any other sites that are recommended here. unless they are official. Listen to your local authorities when conditions are life-threatening or there is possible loss of property.

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THE ENTIRE FIRST PARAGRAPH THAT FOLLOWS  IS A DIRECT QUOTE FROM DR. JEFF MASTERS (PICTURED BELOW) THAT WAS CUT AND PASTED FROM HIS WEATHER UNDERGROUND SITE; DR. MASTERS IS MY MOST RELIABLE AND DEPENDABLE SOURCE WHEN IT COMES TO TROPICAL WEATHER; HE IS A DEDICATED ‘WINNER:”  ONE REASON WHY I DEPEND SO HEAVILY UPON HIS WORK IS THAT HE IS NOT OPERATING UNDER THE CONSTRAINTS OF NATIONAL WEATHER SERVICE FORECASTER BUT HE BENEFITS FROM THEIR INTERPRETATIONS AS WELL AS FROM OTHER NATIONAL WEATHER SERVICE RESOURCES.  HE IS DEDICATED, “UP FRONT,” AND RESPONSIBLE.

Dr. Jeff Masters

The forecast for Ida –

Posted: 10:21 AM EST on November 08, 2009

“The high wind shear of 20 – 25 knots currently affecting Ida is forecast to persist at that level until Monday night. Some slow intensification is still possible while Ida remains over the exceptionally warm water of the Loop Current in the Gulf of Mexico, through tonight (Figure 2). Late tonight, Ida will be crossing over waters of 26°C, which is barely enough to support a hurricane. With shear still expected to be at 20 -25 knots, I expect weakening to begin early Monday morning and accelerate on Monday afternoon. At that time, Ida will encounter 40 knots of wind shear associated with a cold front over the Gulf of Mexico, and begin transitioning to an extratropical storm. Exactly how strong Ida will be when it reaches the coast early Tuesday morning–and indeed if Ida even does reach the coast–is a forecast with high uncertainty. The computer models have a tough time forecasting the evolution of a tropical cyclone into an extratropical cyclone, and the models are all over the place on what will happen. Most of the models foresee a landfall near 1 am EST Tuesday between Mississippi and Pensacola, Florida, then a path northeastward over the Southeast U.S. However, Ida could come to halt before reaching the coast and turn west towards Tampa (the UKMET model’s forecast), or turn south back over the Gulf of Mexico (the NOGAPS model’s forecast). In any case, storm surge and heavy rain appear to be the main hazards from Ida. The GFDL model (Figure 3) is forecasting rain amounts of 4 – 8 inches for a large swath of the Gulf Coast, and there is a risk of tornadoes if the warm air from the core of Ida pushes ashore.”  END QUOTE

From my point of view, (this is Cloudman23 writing) everyone on the Gulf Coast  from Mississippi to Key West should have a “heads up” mindset while Ida is out there.  As Dr. Masters said, the computer models have a difficult time when the tropical to extratropical metamorphoses takes place.  Furthermore, the chance of tornadoes (mentioned by Dr. Masters) in association with warm, moist air from Ida and its inherent instability in such situations, this storm should not be taken lightly.

Ida’s Current Model Forecasts – 11-7-09

The total amount of thermal energy at the surface in the Western Caribbean is high and wind shear aloft is relative low so it is anticipated that Ida will intensify before striking the Yucatan Peninsula.  The Yucatan does not have the type of topography that we associate with significant weakening of a storm due to friction.  But, read what Dr. Jeff Masters says this morning about the fate of Ida after she enters the Gulf of Mexico:

“Once Ida crosses into the Gulf of Mexico on Sunday night, the storm will encounter much cooler SSTs and a strong trough of low pressure that will dump cold air into the storm and bring 40 knots of wind shear. This will cause Ida to lose its tropical characteristics and become a powerful extratropical storm with 45 – 55 mph winds. It is highly unlikely that Ida will hit the U.S. as a tropical storm, but it could still bring tropical storm-force winds of 45 mph to the coast next week as an extratropical storm.”

As for me, I have been favoring the Geophysical Fluid Dynamics Laboratory Model (GFDL) for the path that Ida will take; currently,  if I had to depend upon only one of the many models, that would be the one – in most instances anyway.  I have no real science to back that up – only my perception based upon experience.  Call it a “gut level” good feeling about the model’s past performance if you will.  Therefore I expect Ida to eventually curve rightward as the GFDL shows in the plot below.  By the time it does I expect it will have lost its tropical characteristics though the winds will still be strong.  In other words, it will become extratropical.  TO GET INSTRUCTIONS ON OBTAINING THE GFDL ANIMATION CLICK ON THE FOLLOWING LINK: https://cloudman23.wordpress.com/2008/08/30/gfdl-model-a-great-source-for-an-animation/https://cloudman23.wordpress.com/2008/08/30/gfdl-model-a-great-source-for-an-animation/

The prefix, extra, means “outside of” or “beyond.”  Extratropical cyclones are sometimes called cold core lows whereas tropical cyclones are warm core lows.  When a tropical cyclone draws in cold air (as usually happens when a front interferes with the storm) it becomes extratropical.  The majority of the world’s extratropical cyclones develop in the middle latitudes (30 degrees to 60 degrees latitude) and for that reason are often referred to as middle latitude cyclones.

Graphic courtesy of Jonathan Vigh of the Department of Atmospheric Science at Colorado State University

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Gulf Coast Residents – Ida Is Worth Watching

Ida developed quickly – in fact at a record pace (see Jeff Master’s Weather Blog at http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=1372).

Though relatively high wind shear could prevent Ida from becoming a significant threat to the U.S. mainland it is a storm that is worth watching, partly because warm Gulf waters could nurture it.

Here is a recent forecast plot from the National Hurricane Center (left click to enlarge image):

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