As the United States ended the main part of its 2002 tornado season, it had been the slowest season since 1988. Less than half of the average tornadoes had been reported by July 24th.

The end of July marks the end of the main part of tornado season, but tornadoes have been reported in every month of the year. Killer tornadoes had also been in short supply, with only 11 fatalities reported as of July 24th. Typically, 47 people would have lost their lives in tornadoes by the end of July. The average number of fatalities in a given year in the United States is 57.

Improved warning systems save lives, but the 2002 numbers were quite remarkable. The early part of the tornado season featured a marked absence in killer tornadoes. Indeed, the first reported tornado fatality occurred on April 21st, the latest in recorded history.

Meteorologists at the Storm Prediction Center blamed the low numbers of tornadoes on the persistent drought that had gripped most of the country. In addition, a late winter cold spell across the early season tornado breeding grounds of the Deep South contributed to the slow start.

How did the year end? Well, in terms of the number of tornadoes, the 941 tornadoes that occurred in the year was well less than the twenty year average of 1137. The good luck in term of fatalities continued into November with only 15 through October. But then on November 5th, two people were killed in an Election Day tornado in Southeast Alabama and then 36 people died in the Veteran’s Day Tornado Outbreak on November 10th, including 12 in Alabama.

Meteorologists define fronts as the boundary between two air masses. We have cold fronts where cold air is replacing warm air and warm fronts where warm air is replacing cool air. Then there are stationary fronts where the two air masses on either side of the dividing line are moving very little - usually no movement but perhaps some slight drift. There are also occulded fronts.

Notice I used the term "line." Actually, fronts are drawn on weather maps with a line, usually drawn blue with pointed symbols for cold fronts and red with rounded symbols for warm fronts. But in the real world, fronts are usually not lines. They are boundaries that can often be tens of miles across. And I think that is the situation we are dealing with today.

If you take a look at surface map that includes observations such as one of my favorites at www.rap.ucar.edu/weather/surface you can see how the 'front' has a fairly wide zone to it. The wind was generally out of the north to northwest from about Birmingham northward. So the wind shift often associated with the position of the front would be drawn at about 11:30 am from near Chattanooga to about Birmingham to south of Jackson. The Apalachian Mountains often make it difficult to precisely locate fronts northeast of Chattanooga.

If you look at dewpoints, you see that values south of the wind shift are in the lower 70s. From Birmingham north to Muscle Shoals and Huntsville, dewpoints are running in the 60s with upper 60s at Birmingham and lower 60s at Muscle Shoals. This is the frontal zone and you'd probably be justified in putting the front anywhere within this zone. Once you get into Tennessee, especially Memphis, you see some much drier air with dewpoints in the 50s.

Satellite images are also helpful in identifying the frontal zone. Current visible satellite imagery at that same site I noted above show a limited cumulus field behind the wind shift and almost no lower clouds when you get into the 50-degree dewpoint air.

Weather really is fascinating.

-Brian-

The Sunday map discussion video is on the server at:

http://beta.abc3340.com/weather/video.hrb

What an afternoon we had in Central Alabama yesterday. Thunderstorms erupted around noontime and created a good deal of havoc. The National Weather Service issued a number of severe thunderstorm warnings with a few reports of damage most of which was fairly limited - downed trees and power lines in isolated locations. The good news with those storms was that almost everyone got some rain. As is the nature of showers and thunderstorms, the rainfall amounts varied widely. I measured 0.39" yesterday afternoon but some spots saw over an inch. Thunderstorms erupted again last night - brought me out of my bed with tremendously bright lightning and a very loud chorus of thunder. I got an additional 1.19" of rain giving me a 6-day total of over 3 inches. We certainly needed the rain which will surely help the water supply situation. Unfortnately it looks like we are going right back into a summertime pattern after this short-lived period of some relief from the heat and dryness.

The current weather pattern is not the typical pattern one would expect to see in the summer. A large and realitively deep trough was positioned over the eastern half of the country. The trough is responsible for bringing a rather rare summer cold front into the southeast. The result is that temperatures will be a just a bit cooler today with highs around 89 or so.

As we get into the upcoming workweek, the trough will weaken and the main storm track gradually shifts northward over the next several days. Without an air mass change and the frontal zone hanging around, look for fairly decent chances of showers and thunderstorms for the next couple of days especially south of the Birmingham area. By the middle of the week, the pattern has weakened enough that we should be back into the fairly persistent afternoon shower regime. And temperatures by the end of the week are expected to be back into the mid 90s once again.

The GFS long range outlook is for the heat to return in full force with a strong upper level high over a large part of the country.

Tropics remain quiet. An area of cloudiness in the Southwest Gulf is being watched and upper level winds are becoming a little more favorable for development. However, with the system close to land it looks like any development will be slow to occur.

A BIG thanks to the folks in Calhoun County for coming out to the spotter training class held yesterday morning at the Calhoun County EMA office in Jacksonville. Nearly 40 people gave up their Saturday morning to learn about severe weather. And I really do appreciate that interest. Spotters remain an important part of the warning system, and spotter reports make a significant contribution to saving lives.

I hope you have a great Sunday and a wonderful week. James Spann will be back tomorrow morning with his regular schedule of web video map discussions.

-Brian-

Yesterday, I covered several of the findings and recommendations from the official NWS Service Assessment on their efforts from Hurricane Katrina. Here is a summary of the remaining items.

Because of massive communications failures, several National Weather Service offices in the South had to assume the duties of offices that were affected by the hurricane. Several snafus developed with the new national forecast grid system when the backup officers were unable to upload the data. Backup offices also had problems performing certain tasks that were developed by the affected offices. Procedures will be put in place to handle these problems in the future.

Telephone disruptions caused significant communications hardships after the storm. Alternative communications methods, including high frequency amateur radio equipment or satellite phones will be explored.

Automatic Surface Observing Systems (ASOS) stations are frequently knocked out of commission by power failures or damaged by the wind during landfalling hurricanes. This was the case during Katrina. This obviously hampers the efforts of the NWS. Steps have to be taken to provide backup power and harden this equipment.

Other recommendations included archiving experimental elements of the new National Digital Forecast Database and pre-testing systems when significant events cause major forecast centers to move out of harm’s way in the face of an advancing storm. Finally, requests for information from other Governmental agencies were not well coordinated and better communications protocols will be established.

All of these recommendations will be important in the National Weather Service’s mission of saving lives and protecting property. But, something not to miss is that the report hailed the tremendous efforts of the various National Weather Service offices and the National Hurricane Center.

A 45 minute power failure put a little crimp in my late night forecasting tonight.

My Sony Vaio laptop failed last week and will not get repaired until Wednesday, so I am working on a spare Dell for now. But I have none of my regular celluar modem service since the cards will not fit in the proprietary slots of the Dell.

Anyway, my 11:15 update was wasted since I couldn't post it.

Now...at 12:20...a line of thunderstorms is moving southeastward across Central Alabama. It is not a continuous line. One concentration is over Cherokee County.

The second concentration is near Birmingham. It extends from south of Irondale to near Helena. A large thunderstorm extends west of Helena and Alabaster. The line picks up from McCalla back to the southwest over Sumter and Hale Counties.

The activity is moving SE at 20 mph.

No warnings are in effect, but the storms are associated with lots of dangerous lightning and torrential rains.

They will continue through the overnight ahead of a slow moving cold front.