IDA MODEL FORECASTS – 11-6-09

Thanks to the very fine work by Jonathan Vigh of the Department of Atmospheric Science at Colorado State University I am able to provide you this morning’s model forecasts for Ida.  Left click to enlarge image.

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TROPICAL DEPRESSION HENRI MODEL FORECASTS – 10-8-09

The image below shows model results for Tropical wave (depression) Henri released at 5 PM EDT, Oct. 8, 2009.

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A Tropical Wave Worth Watching Has Formed

-left click twice to enlarge this TIME SENSITIVE image -

The chart above, acquired from the tropical page of Weather Underground at http://www.wunderground.com/tropical/ shows computer model “notions” of the future path of Investigation 91 which currently has the status of a tropical wave.  The wave (or tropical disturbance) is currently showing no signs of cyclonic circulation.  When, or if, if does it will become a tropical depression.

The red pathway is from the GFS image.  This is the one I’m tending to value the most in this specific case since the GFDL does not take it far enough.  In any case, it is believed that the leading half of an anticyclone moving from the west toward the east will prevent the system from continuing its rightward turning and will eventually cause it to move generally toward the west.

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ANA, BILL, AND CLAUDETTE!

To have this current explosion of activity in the Gulf and Atlantic after so many quiet weeks is a real attention-getter.  Most recently, a tropical system off the Florida panhandle has developed into a tropical storm.  In the meantime Ana and Bill out in the Atlantic are both commanding attention.

Tropical systems are not all bad, particularly when the wind velocities are not too high and this is because they can provide much needed precipitation.  Let’s hope that these three systems prove to be more of an advantage than anything else.  So many people are reminded of Andrew in 1992, another year in which El Nino was a  factor.  Andrew was the only hurricane to make landfall in the U.S.A. that season but he was a whopper and there are many people yet today who will testify that it changed their lives – myself included.

I am likely to be inactive on this site for the next few days for two reasons.  My laptop is behaving badly and either needs some serious attention (like a new hard drive) or I need to bite the bullet and get another machine.  Also – I will be traveling.  For those of you who know me – don’t be alarmed.  The traveling has nothing to do with the current tropical weather activity.

In the meantime if you want to stay on top of things weatherwise I recommend the Weather Channel if you have cable and also the Masters’ Blog at http://www.wunderground.com/tropical/

The Masters’ Blog link is usually at the upper part of the page on the right hand side.

Peace be with you!

tat

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TROPICAL DISTURBANCE – JULY 20, 2009

LEFT CLICK TO ENLARGE THIS IMAGE

TIME SENSITIVE! – THIS WAS POSTED AROUND

11:30 PM EST

ON JULY 20, 2009.

A tropical disturbance (also known as a tropical wave) has moved over Barbados and is continuing on its general path toward a direction just a little north of west.  The image above is a color-enhanced infrared.  At the time of this posting, the National Hurricane Center is indicating that they do not expect development into a cyclonic system within the next 48 hours.  To be cyclonic there must be a closed rotation.  tropical depressions, tropical storms, and hurricanes rotate counterclockwise in the northern hemisphere (except in the higher levels of the storms).  For more information on cyclonic circulation in a hurricane go to this link:

http://cloudman23.wordpress.com/2008/09/09/hurricane-circulation-lesson-1/

My most trusted source, Dr. Jeff Masters, at this time expects the disturbance to be torn apart by upper level wind shear within the next few days.

To follow Dr. Masters’ reports, go to the following link:

http://www.wunderground.com/cgi-bin/findweather/getForecast?query=34442

Then, in the “Features” bar at the top, click on Tropical/Hurricane.

That will take you to his Wunderblog feature which usually appears on the right hand side of the page.

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NANA, TROPICAL DEPRESSION 15, INVEST 90L, AND INVEST 99L.

FOR EASIER VIEWING, ENLARGE THE IMAGE WITH A LEFT CLICK.

There is “action” in the Atlantic basin today in-so-much as multiple systems are concerned.  The Gulf of Mexico and the Caribbean are considered to be a part of the Atlantic Basin.  The most immediate concerns reside in Puerto Rico, I should think, due to tropical depression 15 nearby.  If it moves northeastward, as predicted, the island will no doubt get precipitation that it doesn’t need considering the pelting it has already taken this season.

Storms do not get named until they “graduate” from tropical depressions to tropical storms.  But, there is a tropical depression out there today with a name, Nana.  She is “named” because she had reached tropical storm status earlier in her history and she retains that name even though she has now deintensified as was predicted.

That is not uncommon but there has been a very interesting occurrence with Nana.  Wind shear earlier on broke her into two distinct parts.  The northern segment (Nana) is not likely to survive but the southern segment, Invest 90L, stands a chance of intensifying.  Both Invest 90L and Invest 99L are tropical disturbances (also called tropical waves).  If you didn’t already know you might have guess that numbers are assigned to tropical disturbances and when under “investigation” they are labeled with the abbreviation, “invest.”

So, there are four systems out there being watched.

Classification of Synoptic-Scale Lows of Tropical Origin:

1. Tropical disturbance (tropical wave) – An area of organized convection, originating in the tropics and occasionally the subtropics, that maintains its identity for 24 hours or more. It is often the first developmental stage of any subsequent tropical depression, tropical storm, or hurricane.

2. Tropical depression – A tropical cyclone in which the maximum sustained surface winds are 38 miles per hour (33 knots) or less. Characteristically having one or more closed isobars, it may form slowly from a tropical disturbance or an easterly wave which has continued to organize.  NOTE FROM CLOUDMAN23 – By convention, it has been the practice of the National Hurricane Center to associate the beginning of “rotation” with the transition from disturbance to depression.  In fact, in some definitions rotation is an important element.  Generally, this causes no problem because once one or more closed isobars are needed to plot the pressure, rotation has almost always begun.

3. Tropical storm – A tropical cyclone in which the maximum sustained surface winds are from 39 miles per hour (34 knots) to 73 miles per hour (63 knots). At this point, the system is given a name to identify and track it.

4. Hurricane (or another name depending upon geographical location – e.g. typhoon) – The name for a tropical cyclone with sustained winds of 74 miles per hour (65 knots) or greater in the North Atlantic Ocean, Caribbean Sea, Gulf of Mexico, and in the eastern North Pacific Ocean. This same tropical cyclone is known as a typhoon in the western Pacific and a cyclone in the Indian Ocean.

(definitions source is the Weather Channel Glossary found at http://www.weather.com/glossary/a.html

During my long college teaching career I was asked from time to time why such a list was not labeled “Classification of Synoptic-Scale Cyclones of Tropical Origin” instead of Synoptic-Scale Lows. The reasoning is straight-forward.  The first member of the quartet, the tropical disturbance, is not cyclonic.  In order to be cyclonic there must be rotation.  Therefore, though all cyclones are lows, not all lows are cyclones.

FLORIDA MAY HAVE A TROPICAL VISITOR LATER THIS WEEK

Left click on image to enlarge.

From late September on through the remainder of the official hurricane season, systems that can develop into named storms begin to pop up in the Caribbean and Gulf of Mexico.  One such development may be occurring now.

An interesting area in the vicinity of the Yucatan is being watched by the National Hurricane Center.  I have marked the approximate center which is hard to pinpoint since there is no apparent closed surface circulation at this time.  I may have my blue dot positioned a bit too far to the east.  It’s easier to do when using loops rather than stills like this image.  If you want to try that, here is a good page to get some nice loops:

http://www.ssd.noaa.gov/PS/TROP/trop-atl.html

I have looked at some of the models on this one and there are indications that it could eventually move toward Florida and provide significant rainfall.  It is my opinion that interests along the West Coast of Florida should pay attention to this.  Right now the wind shear over the storm is about 20 mph.  There is some chance that it could slowly strengthen as it moves toward the northeast later this week.  Probably around the middle of the week it will be influencing some part of Florida.

Tonie A. Toney

12:50 PM EDT 9-28-08

THE FUJIWHARA EFFECT MAY OCCUR SOON – HEADS UP.

Though if it does occur it won’t be as stark as this Pacific Ocean weather event, but it should still be quite interesting.  If you are interested please read the previous post.  If this is the only one you see, scroll to the top of the page and click “Blog” or go to http://cloudman23.wordpress.com/

Tonie A. Toney (Cloudman23)

PUERTO RICO REPORTS – MORE FLOODING, LANDSLIDES – TROPICAL DISTURBANCE LIKELY TO HEAD NORTHWARD

“Plot provided courtesy of Jonathan Vigh, Colorado State University. For more information about this graphic, click here.”

Dr. Jeff Masters of http://www.wunderground.com/tropical/ reports flash floods and mudslides in Puerto Rico from the tropical disturbance in their vicinity.  Please check it out.  His weather blog is excellent.  You will find it on the right side of the page.

The models are all over the place today.  The GDFL model has been, in my opinion, the best performer over the last couple of years at least.  Please disregard the CLP5 model and the XTRP model.  They are no-skill models that do have a useful purpose but they are not meant to convey an actual forecast.  One day I may write about those models to explain their function but if you are bugged by it and can’t wait, I suggest a Google search.

Please visit the rest of this web-log at http://cloudman23.wordpress.com/.  If you are interested in weather, there are some tutorial items scattered about and more will be added in time.  At the end of this page there is a cue to click to the previous page or the next page.

CARIBBEAN SYSTEM HAS MEDIUM POTENTIAL FOR FURTHER DEVELOPMENT.

TWO LEFT CLICKS WILL ENLARGE IMAGES A GREAT DEAL

According to the National Hurricane Center, the tropical wave in the Caribbean has a medium potential for tropical cyclone development.  For those of you who don’t understand that here is a brief explanation.

In order for a system to be cyclonic there must be a rotation of the wind around a low pressure center.  Presently there is no indication of a closed rotation in this otherwise impressive system.  A tropical wave (also called a tropical disturbance) becomes a tropical depression if rotation begins.  Ordinarily the rotation itself signals a maturing (growth) of the system.  Once rotation begins, the conservation of angular momentum kicks in such that as the wind spirals closer and closer to the center its velocity increases.  Tropical depressions can intensify into tropical storms (39-73 mph) and the latter can intensify into hurricanes (74 or more mph).  Here is the formal statement from the Hurricane Center:

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TROPICAL WEATHER OUTLOOK

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

800 PM EDT SAT SEP 20 2008

FOR THE NORTH ATLANTIC…CARIBBEAN SEA AND THE GULF OF MEXICO…

1. A TROPICAL WAVE…ACCOMPANIED BY A SURFACE LOW PRESSURE SYSTEM OVER THE NORTHEASTERN CARIBBEAN SEA…IS PRODUCING WIDESPREAD CLOUDINESS AND SHOWERS OVER THE LESSER ANTILLES…AND ADJACENT CARIBBEAN AND ATLANTIC WATERS.  THIS SYSTEM IS SHOWING SIGNS OF ORGANIZATION…AND UPPER-LEVEL WINDS ARE EXPECTED TO BECOME A LITTLE MORE FAVORABLE

FOR DEVELOPMENT OVER THE NEXT COUPLE OF DAYS.  A TROPICAL

DEPRESSION COULD FORM DURING THIS TIME AS THE SYSTEM MOVES SLOWLY NORTHWESTWARD.  AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE THE SYSTEM ON SUNDAY…IF NECESSARY.  REGARDLESS OF DEVELOPMENT…LOCALLY HEAVY RAINFALL AND STRONG GUSTY WINDS WILL AFFECT MUCH OF THE LESSER ANTILLES…THE VIRGIN ISLANDS AND PUERTO RICO THROUGH SUNDAY.

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On the infrared satellite image above from the U.S. Naval Research Lab, I have marked two islands that don’t need any more precipitation for a while due to recent tropical systems having dumped heavy (and deadly) loads upon them.  Flooding and mudslides are likely if this disturbance moves as expected, over the islands.  For the same reasons, Cuba also stands a risk of increased problems.

Please visit the rest of this web-log at http://cloudman23.wordpress.com/.  If you are interested in weather, there are some tutorials scattered about and more will be added in time.