Archive for the ‘Radar images’ Category

The Hurricane Season for 2011 Has Begun

Radar Loop of Tropical Storm Fay's Florida Visit - YOU MUST CLICK ON TO ACTIVATE.

By the time you read this, May of 2011 will have ended and the Northern Hemisphere Atlantic, Caribbean, and Gulf of Mexico hurricane season will have begun.  The following link will take you to a summary of the NOAA outlook for this season:

http://www.noaanews.noaa.gov/stories2011/20110519_atlantichurricaneoutlook.html

Please be prepared if you live in hurricane territory.

The loop above illustrates nicely that a tropical system does not have to be a hurricane in order to cause significant problems including fatalities.  TO ACTIVATE YOU MUST LEFT CLICK ON THE IMAGE.  Here is what Wikipedia has to say about the 2008 storm:  Tropical Storm Fay was a tropical storm and the sixth named storm of the 2008 Atlantic hurricane season. Fay formed from a vigorous tropical wave on August 15 over the Dominican Republic. It passed over the island of Hispaniola, into the Gulf of Gonâve, across the island of Cuba, and made landfall on the Florida Keys late in the afternoon of August 18 before veering into the Gulf of Mexico. It again made landfall near Naples, Florida, in the early hours of August 19 and progressed northeast through the Florida peninsula, emerging into the Atlantic Ocean near Melbourne on August 20. Extensive flooding took place in parts of Florida as a result of its slow movement. On August 21, it made landfall again near New Smyrna Beach, Florida, moving due west across the Panhandle, crossing Gainesville and Panama City, Florida. As it zigzagged from water to land, it became the first storm in recorded history to make landfall in Florida four times.   Thirty-six deaths were blamed on Fay.  The storm also resulted in one of the most prolific tropical cyclone related tornado outbreaks on record. A total of 81 tornadoes touched down across five states, three of which were rated as EF2. Damage from Fay was heavy, estimated at $560 million.

Here is a link to Wikipedia’s coverage of that storm:

http://en.wikipedia.org/wiki/Tropical_Storm_Fay_%282008%29

Here is a link to my list of 23 Misconceptions About Hurricanes:

http://ztechzone.net/learningzone/science/science55/hurricanes.html

LAKE EFFECT SNOW

You might have to click on the image to get it to loop. This image courtesy of Weather Underground.

When my television is turned on I “check out” the Weather Channel fairly often. For the most part I’ve been very impressed by explanations that are given about weather happenings. I’ve never done media weather reporting so can only imagine how frustrating it must be to provide good presentations when time is at such a premium. In the college classroom even though I had an agenda with objectives to cover I had control over the amount of time I spent on individual topics.

Recently I heard a Weather Channel reporter give a less-than-desirable explanation for the cause of lake effect snow events. I imagine that time constraints kept her from being more thorough. This is close to what she said: “The cold, dry air behind this front is moving over the warmer Great Lakes picking up moisture and then dumping snow on the land at the opposite side.”

From my point of view that was far too brief leaving out way too much. But – everything is relative. I suspect that most people would prefer her explanation to an hour lecture on the subject from me. But there would likely be one or two in a large class of meteorology students who would be dissatisfied because I left something out or left them very confused. My dad didn’t have the opportunity to teach me much but one of the things that he tried hard to get through to me was, “You can’t please ’em all.”

So – I’m not complaining about the Weather Channel presentations. I think they do a very nice job. But if I were working for them, here is the minimum that I would insist upon (which is probably one of the reasons why I’m not a suitable candidate to work for them – the brevity necessitated by time constraints would drive me up the wall and my tendency toward long-winded discussions would drive them up the wall – LOL):

Cold, dry air moving over a large, unfrozen lake surface picks up moisture in the form of water vapor made available by evaporation. More often than not unfrozen lake surface water’s temperature is higher than that of the air behind a cold front.

But in most cases clouds that provide precipitation form as a result of air rising and that is most definitely a factor in bringing about lake effect snow events. So – what makes it rise?

The moisture-laden air can rise because of an increase of elevation on the downwind side of the lake but that alone is usually not enough to create snow-producing clouds unless the increase is due to a plateau or mountains. Also, positive buoyancy can cause the air to rise and that can be created in two ways as the air is traveling over the lake water. Picking up heat energy the air can begin to lift (heated air tends to rise); a fair analogy is a hot air balloon. Also, the addition of water vapor to air can increase its buoyancy (as the specific humidity increases, the density increases so long as the temperature of the air does not drop significantly).

The factor most often omitted in a lake effect discussion of why air rises to form snow clouds is this: When air reaches the land it slows down because of the decided increase in friction. When in heavy traffic a car far ahead of you slows down – you, the cars ahead of you, and the cars behind you tend to squeeze closer together. We say the cars are converging (getting closer together). In the case of the fluid air a vertical component of motion is allowed so some of the air “piles up” and therefore moves up. Have you ever heard of cars piling up?

Therefore, even without an elevation increase of the surface over which the air flows and even without an increase in buoyancy, some air on the downwind side of a Great Lake is likely to rise because of convergence. Whether or not snow clouds form is dependent upon a combination of factors.

You’ll have to admit that my explanation is more thorough than “The cold, dry air behind this front is moving over the warmer Great Lakes picking up moisture and then dumping the snow on the land at the opposite side.” The trouble is, it took time, is very “wordy” and you really have to read carefully to pick it all up. Furthermore, as long as my explanation is, it still does not give all of the reasons behind lake effect snows. Also, it makes a blanket statement (as the specific humidity increases, the density increases so long as the temperature of the air does not drop significantly). But it does not elaborate. For most people that sounds like a real paradox – adding moisture to the air can make it less dense and therefore be a contributing factor to its rising! It’s true – and I intend to discuss that paradox on this web-log in the near future. By the way – a friend of mind from way back in high school defines paradox as “two physicians.”

 

YOU MIGHT HAVE TO CLICK ON THE IMAGE ABOVE TO GET IT TO ENLARGE AND LOOP.

In the radar loop above taken from a small time segment (48 minutes) earlier today (12-6-2010), you see the signature of lake effect snows in Indiana. Lake Michigan’s mean elevation is a bit over 577 ft. above mean sea level. The land between Lake Michigan and Fort Wayne is as much as 250 feet higher but I think it’s unlikely that 250 feet of elevation increase is going to create that much snow. Nor is the land heating the air to make it rise via positive buoyancy. In fact, the land surface temperature is colder than the air flowing over it. I believe that it’s convergence of the type I’ve described in this entry that is responsible for much of the snow.

TROPICAL STORM PAULA NOW OVER WESTERN CUBA – 10-14-2010 A.M.

 

Left click to enlarge (which also may trigger motion).

 

Hopefully you are able to see the counterclockwise rotation of Paula in the radar loop above.  Computer models are in general agreement that this storm is not likely to survive much longer.  Most models have the storm continuing to turn to eventually head toward the southeast – but in a very weakened state.  A combination of shear aloft and movement over Cuba is likely to spell the end of her.  However, it is never safe to assume such predictions as Gospel truth.  Interests in the area (including South Florida) should remain alert.

 

FLORIDA’S RAINY SEASON – 2009

If you wish to see other posts on this web-log but are unable,

please click on the “blog” tab near the top of this page.

A related post, “Why Is Florida So Humid” has been added.

It can be found here:

https://cloudman23.wordpress.com/2009/07/04/why-is-florida-so-humid/


About a third of the way into May I noticed that television weather reports and a few of my acquaintances were starting to suggest that “perhaps” Florida’s rainy season had begun.   To be sure, before the middle of May many parts of Florida had been experiencing very significant rainfall events, some of those places on a daily basis.  One of those places was northeast Citrus County where I live.  However, I doubted that those rainfall events signaled the beginning of the “real” rainy season because my experience living much further south in Florida had conditioned me to considered the “true” rainy season to be that time when precipitation was due almost entirely to mesoscale systems, namely sea breezes and sea breeze convergence within the peninsula.  And – unless the views were severely obscured by buildings or dense stand of trees, at those times one can detect evidence of thunderstorms within hearing and/or seeing distance on almost a daily basis.

Florida’s rainfall this May was almost entirely due to weather systems of a much larger magnitude than the mesoscale – systems that show up on the national weather maps (middle-latitude cyclones with their associated frontal weather, et. al.).  Those systems, along with anticyclones (rotating highs) are often referred to as synoptic systems.

I’ve always found it interesting that the majority of our annual precipitation in peninsular Florida occurs (on the average) as a result of weather systems far smaller in magnitude than either the mid-latitude synoptic systems or the tropical synoptic systems such as hurricanes and tropical storms.

Here are three graphic illustrations of the synoptic nature of our May events followed three more images of today’s weather (June 2, 2009) over the Florida peninsula.  Comments labeled A through F  follow each illustration:

5-17-09loop2238z

70 minute loop begins 5:28 pm EST, May 17, 2009

MOST ALL IMAGES IN THIS WEB-LOG ENLARGE

WITH A LEFT CLICK OR TWO

AND

IN MOST CASES IN ORDER TO ACTIVATE LOOPS

YOU MUST FIRST ENLARGE.

A.  In this 70 minute loop (starting at 5:28 PM EST on May 17th notice the cold front that shows up well along a line from eastern Tennessee down to southern Mississippi.  If one were to see only the Florida peninsula portion of this image I can see how he/she might immediately assume that this was a sea breeze convergence day.  But as you can see, this is pre-cold frontal weather being drawn northward.  Not to say the warmer land surface and some convergence did not play a role, it is nonetheless clear that the weather is dominated by the synoptic scale.

5-17-09seLoop0328

B.  This 70 minute loop of the same system shows very nicely the pre-frontal nature of Florida’s rainfall by virtue of the fact that it has moved on in accordance with the general motion of the cyclone across the United States from west to east.  This loop starts at 11:28 PM EST on May 17th.

5-26-09 2100z SurfC.  Here is an impressive array of alternating lows and highs of the synoptic scale on May 26.  At this time the movement of the lows was almost perfectly synchonized in the diurnal mode so that each day, with the help of the intense heating of the peninsula, we got significant rainfall in my neighborhood (latitude 29˚North by longitude 80.4 West – to the nearest 10th of a degree).  Notice the lows centered off the Georgia coast, south-central Alabama, and Texas – all three with associated troughs.  Each of those provided my neighborhood a great deal of rain and certainly cramped my style as I was attempting to spend a lot of time outdoors landscaping and doing my annual manicuring of my woods.  But – because of three years of drought here, I was thanking the Great Guy In The Sky for each and every drop and respecting His audible commands to stay safely indoors in the form of lightning hits that were uncomfortably close.

I was surprised to learn recently that the National Weather Service Forecast Office has declared May 11 to be the beginning of the 2009 “rainy season” of Florida.  This is a full 9 days ahead of May 20, the mean starting date.  Who am I to disagree with the experts?  It matters not in the real world I suppose – only in the academic world in which people like me often get lost.  The bottom line is that we need the rain and no matter whether May’s events were “true, traditional” rainy season events or not, they were a blessing.

Now lets take a look at weather over the peninsula a little earlier today.

6-2-09 sea breeze

UNLIKE THE FIRST TWO IMAGES –

THIS IS A STILL – NOT A LOOP.

D.  Today, June 2, 2009, the radar shortly before 3 pm EST is showing precipitation as a result of sea breeze “fronts” along both sides of the peninsula.  I suspect convergence is occurring in the south part as shown by the beginning of development over some of the glades south of Lake Okeechobee.  This is more like a Florida “rainy season” day as I have learned to know it but even today – a synoptic system is providing a noticeable influence (see next two images). For those of you who live in my neighborhood, the Crystal River winds at the time of this observation were 7 mph from the west and that is ample to bring in moist air which is rising over the heated land to form the showers that are appearing on this radar image.

6-2-09 628pEST rad ed

E. Later today the thunderstorms became more intense and in the still radar image above you can see a decided concentration toward the western side of the peninsula.

6-2-09 333p ESTsurf

F.  And here is a synoptic map showing the low (with its associated fronts) that is influencing Florida’s weather today.  There is a “rule of thumb” in meteorology that the air ahead of a front moves more or less parallel to that front.  If you will simply extend in your mind’s eye the warm front further toward Florida you will realize that there is a force over most of Florida tending to make smaller weather systems (like mesoscale thunderstorm complexes) move toward the WNW.  Apparently the winds aloft are not strong enough to counteract that.

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Here are some interesting statistics for two locations in Florida providing some geographical contrasts along the peninsula.

Ocala averages almost 50” of rainfall per year of which nearly two-thirds falls in May through October.

Homestead (south of Miami) averages nearly 60” per year of which over three-fourths falls in May through October.

Here are the actual numbers (statistical means):

Ocala (in Central Florida) 49.68” annual     31.10” May through October = 62.6%

Homestead (south of Miami) 58.20” annual    45.70” May through October = 78.5%

For further information about Florida’s rainy season  here is a safe link in the pdf format from NOAA.

http://www.srh.noaa.gov/images/mfl/news/Rainy_Season_Beginning_2009.pdf

Yours Truly,

Tonie A. Toney

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please click on the “blog” tab near the top of this page.

TORNADO WARNINGS TONIGHT – SOUTH GEORGIA, NORTH & CENTRAL FLORIDA

4-2-09-848pest1

MOST IMAGES ON THIS WEBLOG ENLARGE WITH LEFT CLICKS

Tornado and severe weather warnings were released about 30 minutes ago for South Georgia, North and some of Central Florida.  As the night progresses it is likely that more of Central Florida will be involved.  My county, Citrus, has already been alerted.  Please be sure that you take whatever precautions you are equipped to take in such circumstances.  If you have a weather alert radio please be sure it is positioned so that it will awaken you to critical bulletins.

This alert has been triggered by severe squalls out ahead of a cold front.  Currently the warnings are in effect to as late as 5 am but there is a chance that more alerts will be issued tomorrow as the front moves further in to Florida.

Other parts of our Country are experiencing severe weather with a different system – e.g. Alabama, Tennessee.

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please click on the “blog” tab near the top of this page.

Florida Experiencing an Impressive Band of Cumuliforms

28 AM EST, 12-11-2008
10:28 AM EST, 12-11-2008

The jury is still out on whether or not Florida will experience violent weather with this system.  Cyclogenesis (birth of a cyclone) at the frontal boundary occurred sooner than I had expected – north of the Gulf instead of over the Gulf as I had previously speculated.  My advice is to keep your eye on the weather today.

Cloudman23

FLORIDA WEATHER ALERT FOR CERTAIN GULF COASTAL COUNTIES

LEFT CLICK IMAGE TO ENLARGE
LEFT CLICK IMAGE TO ENLARGE

Target Area = the following Florida counties:

Levy,  Citrus, Hernando, Pasco, Pinellas, Hillsborough

Event: Coastal Flood Statement Effective:18:38 CDT on 12-10-2008 Expires:09:00 CDT on 12-12-2008 Alert:

…INCREASING WINDS AND SEAS WILL RESULT IN HIGHER THAN NORMAL TIDES AND HIGH SURF ALONG THE FLORIDA WEST COAST THROUGH THURSDAY NIGHT…

.AN AREA OF LOW PRESSURE IS EXPECTED TO DEVELOP OVER THE NORTH CENTRAL GULF OF MEXICO AND QUICKLY STRENGTHEN AS IT MOVES NORTHEAST ACROSS THE SOUTHEASTERN STATES TONIGHT AND THURSDAY AND EVENTUALLY UP ALONG THE MID ATLANTIC COAST THURSDAY NIGHT AND FRIDAY. AS THIS SYSTEM MOVES BY TO THE NORTH IT WILL DRAG A STRONG COLD FRONT THROUGH THE GULF WATERS TONIGHT AND THURSDAY.

AHEAD OF THIS FRONT SOUTHEAST TO SOUTH WINDS ARE EXPECTED TO INCREASE TO NEAR 20 KNOTS WITH SOME HIGHER GUSTS LATER TODAY AND

TONIGHT THEN SHIFT INTO THE WEST AND NORTHWEST AT 20 TO 25 KNOTS WITH HIGHER GUSTS DURING THURSDAY AND THURSDAY NIGHT.

INCREASING SOUTHERLY WINDS AHEAD OF A COLD FRONT AND STRONG WESTERLY WINDS IN ITS WAKE WILL HELP TO BUILD SEAS OVER THE ADJACENT GULF WATERS THROUGH THURSDAY NIGHT. THE INCREASING WINDS AND SEAS WILL CAUSE TIDES TO RUN SOME 1 TO 2 FEET ABOVE NORMAL FROM TAMPA BAY NORTH TO THE SUWANNEE RIVER…WITH THE POTENTIAL FOR 2 TO 3 FEET ABOVE NORMAL TIDES FROM HOMOSASSA NORTH THROUGH CEDAR KEY TO THE SUWANNEE RIVER.

THESE ABOVE NORMAL TIDES MAY CAUSE SOME MINOR COASTAL FLOODING AND OVER-WASH AS WELL AS MINOR BEACH EROSION AT TIMES OF HIGH TIDE THROUGH THURSDAY NIGHT. IN ADDITION THE RISK OF RIP CURRENTS AND STRONG UNDERTOWS AND LARGE BREAKING WAVES ALONG AREA BEACHES WILL ALSO BE ON THE INCREASE.

RESIDENTS LIVING ALONG THE COAST SHOULD MONITOR WATER LEVELS THROUGH THURSDAY NIGHT AND BE READY TO MOVE TO HIGHER GROUND SHOULD FLOODING BE OBSERVED.

STAY TUNED TO NOAA WEATHER RADIO OR YOUR LOCAL MEDIA FOR FURTHER UPDATES ON THIS DEVELOPING WEATHER SITUATION.

_______________________________________________

I personally recommend that residents of the counties mentioned above and also adjacent inland counties pay attention to the weather tomorrow (Thursday).  Cyclogenesis is predicted to occur along the front over the Gulf and that could cause it to swing around rapidly – generating a dangerous squall line ahead of it.  The radar image above shows a squall currently out ahead of the front itself and I have no reason to believe that it will dissipate any time soon.  So – expect squally weather tomorrow and plan accordingly.

Yours Truly,

Cloudman 23 (Tonie A. Toney)


CAMAQUEY, CUBA RADAR OF PALOMA – SATURDAY EVENING

The image loop below is from Camaquey, Cuba

radar covering from 6:45 to 7:45 PM EST 11-8-2008.

Please left click on the image for 15 minute interval animation.


SORRY - THIS WILL NOT ENLARGE

HURRICANE MISCONCEPTIONS – A LIST OF 23

Image source of Ike radar loop = WeatherUnderground.com

Image source of Ike radar loop = Weather Underground

LEFT CLICK IMAGE TO ENLARGE AND SEE A RADAR LOOP OF IKE AS HE COMES INTO VIEW AND EVENTUALLY MAKES LANDFALL.  WATCH FOR A DISTINCT RIGHT TURN TRACKING DIRECTLY TOWARD HOUSTON JUST BEFORE REACHING THE COAST.  IF IT HAD CONTINUED STRAIGHT, THE WINDS AND THE SURGE ALONG THE COAST AT GALVESTON AND SOUTHWESTWARD WOULD HAVE BEEN EVEN WORSE BECAUSE THAT COAST WOULD HAVE BEEN CROSSED BY THE RIGHT-HAND LEADING QUADRANT OF THE STORM

(see item 13 below).

23 COMMON MISCONCEPTIONS ABOUT HURRICANES

©* Tonie Ansel Toney (see conditions for copying at the end)

https://cloudman23.wordpress.com/

I have learned of these misconceptions by communicating through the years with my students, friends, neighbors, attendees of some of the hurricane seminars that I have conducted and visitors to hurricane expos where I have given presentations.  Most of this occurred in Florida.  I learned that these items have been relatively “common” misconceptions through informal pre-tests I have given to college students at the beginning of certain semesters, answers to questions I have asked in classes during the course of myriad semesters, through conversations with people of all walks of life (and a broad range of ages and experience), and by listening carefully.

ALL 23 UPPER CASE STATEMENTS ARE FALSE IN SOME WAY.  BRIEF EXPLANATIONS FOLLOW.

1. IF THE SPEED OF WIND BLOWING DIRECTLY INTO THE SIDE OF A DWELLING CHANGES FROM 40 MPH TO 80 MPH, THE FORCE THAT IT EXERTS INTO THE STRUCTURE WILL INCREASE TO TWICE WHAT IT WAS. THE TRUTH: A doubling of the velocity will cause a four-fold increase of the force upon a surface being struck at right angles.  The relationship is “exponential,” not “linear.”

2. IF, DURING A HURRICANE, YOUR TRUE WIND DIRECTION IS FROM THE SOUTH, THE HURRICANE’S EYE IS TO THE NORTH OF YOU. THE TRUTH:  It is generally west of you.  Hurricane winds move approximately parallel to (or concentric with) the nearly circular eye-wall.  A good rule-of-thumb for eye location (in the Northern Hemisphere) is: Imagine standing with the wind at your back.  Extend your left arm out from your side and your hand will be pointing toward the eye.

3. IF AN APPROACHING HURRICANE IS ABOUT ONE DAY AWAY, PRUNING OF TREES IS ADVISABLE. THE TRUTH:  It is too late to prune at that time – it should have been done much sooner, preferably prior to the hurricane season.  Pruned material must be disposed of properly – if lying around the items can become a dangerous airborne hazards. Please read on by clicking here; there are 20 more which might interest you. And, don’t miss viewing the animated image of Ike at the beginning of this post.