Weather Camp Presentation 2009: Sea Breeze Interactions In Florida, And What The Reactions Are From Some Of those Interactions

This post is based on the presentation I made for the 2009 Jackson State University Weather Camp.

To start off, we have to ask the question, "What is sea breeze?". The answer to that question is below...

Sea breeze is wind from the sea that forms on the land near the coast.

Why and how does it form?

Sea breeze forms because of a temperature difference over the land and water, which together to create a pressure gradient over the land. This difference causes higher pressure and cooler air to move inland.
There are six main steps of sea breeze formation, given below.
1. Warm air over land rises.
2. Sea breeze moves inland.
3. Clouds develop and move towards the sea.
4. Upper level return of the land breeze.
5. The cool air aloft sinks over the water.
6. Sea breeze front forms.
 

The sea breeze can interact with other atmospheric features, and often form pulse thunderstorms. Here is an image that shows the East and West Coast sea breeze, as well as an outflow boundary interacting to form a tornado in Tampa.

Severe Weather Today

The threat of severe weather exists across the area today, courtesy of a low pressure system moving through the Southeast. The main concerns will be large hail and damaging winds, but there could also be a few isolated tornadoes across Central Florida, as there is enough instability and wind shear to cause some of the stronger storms to rotate.

We'll also see our typical pop-up thunderstorm pattern, as outflow boundaries from the storms interact with the atmosphere.

Most of the area is under a Tornado Watch until 8pm. As mentioned at that link, we could also see wind gusts up to 80mph, and 2 inch hail.

This looks to be mainly a daytime event. The storms should die out after sunset, because the cloud cover will prevent the heating required to carry the storms through the night.

We also have a chance for severe weather tomorrow. Will update again later to talk about that.

Possible Severe Weather Tomorrow

*** UPDATE 1/25/10  12:15pm***

After looking over some data, I have several things to talk about regarding today's potential severe weather. There is a decent instability, and strong vertical wind shear. This means potential for tornadoes. The NWS has hinted that some of these could be long-tracked, if they develop. Isolated showers and thunderstorms will start to effect us within a few hours, but the biggest severe weather threat looks to be late afternoon through the evening. Damaging winds and tornadoes are the biggest threat today, although I won't rule out some hail.

As we move into the evening hours, look for a aquall line to develop, and move across the area. This line of thunderstorms could have embedded supercells, and will probably bow out in some spots. We will also see locally heavy rainfall between 1 to 3 inches, something that could potentially create flash flooding.

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Severe weather is possible across Central Florida tomorrow.

A low pressure system is developing in the Gulf of Mexico, and will track through South Georgia tomorrow and tomorrow night. The Storm Prediction Center has Florida in a Slight Risk area for severe weather. Deep moisture levels and strong upper level winds will combine with decent atmospheric instability to create conditions that will be conducive for a squall line to develop ahead of the cold front. The timeline for strongest storms looks to be late afternoon going into the evening, and overnight for some locations. The main threat tomorrow will be damaging winds, hail, and isolated tornadoes in the stronger parts of the storm. Will update in the morning to reflect any changes, and to highlight any watches/warnings.

Weather Radar History, and the Impact Made by the WSR-88D

I've been trying to think of something interesting to write about. I decided to write a brief history of weather radar, and the impacts made by the WSR-88D Next Generation Radar (NEXRAD) system.

First, a brief explanation of how radar works, before we go into the history of Doppler Radar.

The term "RADAR" stands for RAdio Detection And Ranging. Doppler radar works by sending out radio waves, known as pulses. When these pulses hit an object, such as a raindrop, they bounce back to the radar, and calculations are made to determine storm position. (This is a basic description of how radar works. If you want to know more, here is a link to the NWS.)

There are several types of radar products offered by the WSR-88D (go here for more info, as this is only a basic explanation):

Reflectivity, which shows storm intensity based on the amount of energy reflected back to the radar.

Velocity, which shows the motion of the target object currently in the path of the radar beam.

There are also two precipitation products. One attempts to estimate the rainfall amount expected within one hour, and the other attempts to estimate the total amount of rainfall a given storm will produce.

Now, the history.

 The British were the first to develop devices that could locate thunderstorms, through the work of Sir Robert A. Watson-Watt, in 1935. From 1942 to 1944, work was done at the Massachusetts Institute of Technology's Radiation Laboratory that helped show that storms could be seen on certain types of radar systems, and at different wavelengths, up to distances of 150 miles. Work continued during WWII, and through research conducted at harbor defense radar systems in Panama, many basic features of storm structure were discovered.

After WWII, the Weather Bureau was able to acquire AN/APS-2F aircraft radar systems from the U.S. Navy. These were renamed Weather Surveillance Radars with designations ranging from 1, 1A, 3, 4, and  deployed slowly, with around five per year coming into operational use. The first WSR was deployed on March 12th, 1947 in Washington, D.C. A second WSR was deployed in Wichita, Kansas on June 1st. Eventually, radar systems were being made specifically for use by the Weather Bureau. These were known as AN/CPS-9 Storm Detection Radars. In the 1950s, more advancements in radar technology were made, and in 1953, hook echoes (a feature seen on radar that indicates a tornado) were first seen on a radar in Illinois.

Fast forward to 1990: A new WSR system is implemented in Norman, Oklahoma. This new Next Generation Radar (NEXRAD) system, the Weather Surveillance Radar 1988 Doppler, was the result of many years worth of advancements made in radar technology. These Next-Gen systems are currently deployed at every National Weather Service office nation-wide, as well as many military installations.

Currently, plans are being made for even more advancements. The National Severe Storms Laboratory (NSSL) is working on phased-array radar systems.  WSR-88D radar transmits one beam of energy, then has to wait for the pulse to return before going to the next elevation angle. When it has finished scanning every angle it starts the process over. By this time, six to seven minutes have passed, and in that time, the storm could be over, or have produced a tornado that was missed by radar.  Phased-array radar on the other hand, sends out multiple pulses one at a time, so the radar has no need to tilt to look at the different elevation angles. This results in scanning times of about 30 seconds, which is much, much faster than what the WSR-88D is capable of. Having the ability to do a complete scan in 30 seconds will enable forecasters to see storms better, and will help to increase warning times in severe situations. Unfortunately, phased-array radar will most likely only be installed in select areas.

In closing, radar has come a very long way from the early technology of the 1940s and '50s and is constantly improving. Just imagine what we'll be looking at in 20 years.

Extreme Weather: A Book In Review

As I've been away from this blog and haven't posted anything for the past three months (and two days, technically), I am wanting to get back to it. To ease myself back in, I'm going to write a review of an excellent book I read recently.

This book, Extreme Weather: Understanding The Science of Hurricanes, Tornadoes, Floods, Heat Waves, Snow Storms, Global Warming And Other Atmospheric Disturbances; was written by H. Michael Mogil, a professional meteorologist living in Naples, Florida. He also runs his own company, How The Weather Works.

If you are wanting to learn about weather, this is the book for you. 304 pages long, with a reference section that includes links to information related to each chapter, a glossary, and a list of recommended books for further reading. On top of all of this information it is an extremely well-written book. I have read a lot of weather-related books, and this one is the best of my collection, and that includes several college level meteorology books I've been given. Not only was it well-written, it was also very easy to understand. Several of the topics discussed are somewhat complex, but in this book they are explained in a way that is both easy and fun to read. Despite already having read about a lot of the information in the book, I found that I could not put it down and was highly disappointed when I had finished it.

Even if you've read weather books before, you haven't read one like this. I highly recommend it to anyone interested in weather, regardless of their  knowledge level. Extreme Weather is not a one-stop shop, as it doesn't cover everything weather-related, but it does exactly what it was intended to do in providing an easy, fun to read resource for those interested in weather.

The topics covered include tornadoes, heat waves, floods, snow storms, and global warming. Each topic has around 30 pages devoted to it. In those approximately 30 pages, there is just about everything you need to know about the subject matter (at a basic to intermediate level). Overall, it is an amazing book that had a lot of time and effort put into it. The result is a phenomenal piece of work that is definitely in my top ten (among my weather books, #1), and one that you are sure to enjoy.

We don't have much longer. Pretty soon, the 2010 Atlantic Hurricane Season will be over. To date, we've had 15 named storms, with 8 hurricanes. 5 of those hurricanes were considered major (Category 3+). There is a disturbance the NHC is watching for development in the Caribbean moving west towards Nicaragua, but it doesn't look like it will amount to much.

Back here in West Central  Florida, we've got nearly perfect weather.  Daytime temperatures will be in the mid to upper 80s, while night-time temps will be in the 50s and 60s. Dry air will remain over the area, as high pressure moves in.

On a side note, I've just joined Foot's Forecast, a national group of high school and college students forecasting the weather. I'm the first in Florida to join. If you'd like to check them out, the main site is www.footsforecast.org, and the Florida section is on Facebook ( http://www.facebook.com/pages/Foots-Forecast-Central-Florida/164039986941236?v=wall ). The Florida page covers Central Florida, including the cities of Brooksville, Tampa/St. Petersburg, Orlando, and Kissimmee. Disney and Universal will be mentioned regularly, so if you are planning a trip to either one, be sure to check on the weather before you get there.

A Look Into The Future....

Well, here we are. Let's take a look into the meteorological crystal ball....

The first day of autumn (or fall, depending on what you call it) is tomorrow. Usually, as we head into October and November, temperatures cool down and in some places get downright frigid. Unfortunately, the key term here is usually. Climatologically speaking, we have had one of our hottest years on record in the U.S. and that trend looks like it will continue through the rest of the year. 2010 has already tied 1998 for hottest global year on record, and will most likely surpass 1998 as we wrap the year up.

We have had record SSTs as well, which has contributed greatly to hurricane formation in the Atlantic this hurricane season. You've probably noticed how quickly things have intensified, and how we've had several storms stronger than usual in places where they normally aren't.

Getting back to our topic, here is the current outlook for temperature and precipitation probabilities in the U.S. for the period  from October through December:

Temps:
http://www.cpc.ncep.noaa.gov/products/predictions/long_range/lead01/off01_temp.gif

Precip:
http://www.cpc.ncep.noaa.gov/products/predictions/long_range/lead01/off01_prcp.gif