The Florida Drought Continues

The Florida drought is getting worse, due to a major lack of rain across the state.

Locally, the Tampa Bay Area (more specifically West Central Florida) is the only part of the state not affected by the drought at some level, although that will likely change in the near future as we transition into summer and we really start to heat up.  Below is an image showing the percentage of the state at each level of drought, and the progression of the drought through the past year.

Hurricane Season Preparedness

It's that time of year again. The time when you should be getting ready for hurricane season.

NOAA is predicting an above average year, with 12 to 18 named storms (winds of 39 mph or higher), of which 6 to 10 could become hurricanes (winds of 74 mph or higher), including 3 to 6 major hurricanes (Category 3, 4 or 5; winds of 111 mph or higher). However, it only takes a single storm to change your life forever. You can go here to make a family disaster plan.

Today marks the start of National Hurricane Preparedness Week. Each day, there will be a different topic to focus on.

It has been 90 years since the Tampa Bay Area had a major hurricane make direct landfall. That last hurricane struck on October 25th, 1921. In 2004, Hurricane Charley almost hit Tampa directly, but made a turn at the last minute. We can't predict when a hurricane will hit the area, but we know that sooner or later, one will come. When it comes, Tampa could be wiped off the map. 

A Winter In Review: New York City

I've watched for the past few months as New York City has literally been BURIED in snow. Now, I would like to take you through a brief analysis of New York City's own extended version of "Snowmageddon". (The data shown here is from the period of November 2010 to March 2011, and was recorded at the NWS ASOS in Central Park.)

In November, New Yorkers experienced a quiet month of wintry precip, recording 0.4 inches of snow. By December however, things had taken a turn, and winter was in full swing with a nice 20.1 inches falling in the city (20 inches of that amount came during the 24 hour time frame of the 26th to the 27th).

January saw another whopping 36 inches accumulate, courtesy of several nasty winter storms. At times, NYC experienced conditions that you would expect in North Dakota. January 2011 is ranked #2 on the Top 10 Snowiest Months list for NYC, with 36 inches of snowfall, just 0.9 inches away from the number one spot.

The month of February came and went leaving in it's wake 4.8 inches, an amount that caused a sigh of relief among snow-weary New Yorkers, but only because it wasn't as bad as January and December. In March, the icy grip of winter released it's hold on New York City, only dropping an inch of snow.

In all, from November 2010 to March 2011, a staggering 61.9 inches fell in the Big Apple, which is a long way from the 20 inches of snow that normally fall during a New York City winter. Pictures that were sent to me in January by a friend in Manhattan are below.

Yazoo City: Looking Back One Year Later

Tomorrow is the one year anniversary of the Yazoo City, MS EF4 tornado. On April 24th, 2010, a devastating tornado roared through Mississippi, causing extensive damage around Yazoo City, and becoming the 4th longest-tracked tornado in state history.

Comparisons have been made between this tornado and the EF5 tornado that obliterated 95% of Greensburg, Kansas on May 4th, 2007. Similar destruction likely would have taken place in Yazoo City, had the tornado not missed the downtown area by two miles. Storm Chaser Vincent Webb was on-site, with footage that can be seen here.

The NWS in Jackson, MS estimated that the tornado had a max wind speed of 170 mph, along with a damage path 149 miles long. A radar loop showing base reflectivity (left) and storm relative velocity (right) can be found here (the loop may be slow to load). Here is a radar image of the tornado when it was over Yazoo City.

I was in Jackson from June 7th to the 11th for the 2010 NOAA Weather Camp that was held at Jackson State University, and the camp had the privilege of getting to tour spots along the damage path around Yazoo City. Below are some pictures I took of the damage.

Recent Severe Weather Across The South

We've had some crazy severe weather across the South in the past few days. Thankfully, the threat of severe weather has ended. Sadly, 30+ fatalities have been confirmed, along with a large number of injuries.


From April 14th to the 16th, the US saw 1,003 total storm reports, 241 of which were for tornadoes. These numbers are still under review, and it is likely that they will change as the NWS conducts storm surveys.

Here is a report from NWS Little Rock regarding the outbreak in Arkansas. This post will focus on Mississippi, Alabama, and North Carolina.

Mississippi was hit pretty badly from these storms. So far, the NWS in Jackson has confirmed 5 tornadoes. Of these, 2 were rated EF3, with winds estimated at 140 mph. Video and pictures can be found at Mississippi Storm Chasing.
Surveys are still being conducted in Alabama and North Carolina. Preliminary information for Alabama can be found here, along with a video of a tornado. For North Carolina, here is a video of one of the tornadoes approaching Raleigh, as well as an analysis by Dr. Greg Forbes from The Weather Channel.

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.