It was good to see a local group of amateur radio operators in the ABC 33/40 studio Tuesday night. The group was from ALERT, the Alabama Emergency Response Team, which consists of ham radio operators around north and central Alabama that help coordinate communications with the National Weather Service during severe weather events. Meteorologist Brian Peters of our staff gave the tour, and I had a chance to share a few words. Brian is a licensed amateur radio operator; his call sign is WD4EPR, and my call sign is WO4W. I got my first amateur radio license way back in 1970 when I was 14 years old. I still love the hobby, and I current serve as the Public Information Coordinator for the Alabama section of the American Radio Relay League, the national amateur radio organization. I cherish my teenage years when I spent countless hours volunteering with the Tuscaloosa county Civil Defense, acting as a storm spotter and often serving as “net control” at the emergency center. John Oldshue is also a licensed amateur radio operator; his call sign is KE4LMU.

If you have an interest in weather and storm spotting, getting your amateur radio license is a “must”. The most popular license for beginners is the Technician Class license, which requires only a 35 multiple-choice question written examination. The test is written with the beginner in mind. Morse Code is not required for this license. With a Technician Class license, you will have all ham radio privileges above 30 megahertz. These privileges include the very popular 2-meter band. Many Technician licensees enjoy using small (2 meter) hand-held radios to stay in touch with other hams in their area. Technicians may operate FM voice, digital packet (computers), television, single-sideband voice and several other interesting modes.

Here are some helpful ham radio links:

American Radio Relay League:
http://www.arrl.org/hamradio.html

Birmingham Amateur Radio Club
http://www.w4cue.com

ALERT
http://www.alert-alabama.org/

Some fresh notes updated at 9:25 PM

.....Jon Pace, News Director for WTDR-FM, Anniston/Oxford, reports big wet snowflakes along the Talladega-Clay County line in East Central Alabama at 8:50 PM. He was driving through the area and reported by cell phone. The big wet flakes continued for about 10 miles into Clay County toward Ashland. There were no signs that the snow was sticking even to the grassy areas at the time.

.....The 9 PM temperarture atop Mt. Cheaha was still 32--unchanged during the last hour so I feel sure there are some big wet flakes on Alabama's highest point also.

.....In NE Alabama it has dropped to 33 degrees in Mentone at an elevation of 1765 feet. Mentone, of course, is on Lookout Mountain in Dekalb County near Desoto State Park.

.....Overall, the precipitation is diminishing and becoming more patchy.

.....Just took my little dog on a half-mile walk and here in Trussville it is a mix of a cold light rain and drizzle. Used my flashlight beam to hunt for snowflakes. There were none. The rain has been steady for several hours and the rain total here so far is 0.19 of an inch.

.....Snow rumors are rampant. At church tonight, a record number of people asked me if it was going to snow. I almost began answering "no" like the guy in the Capitol One commercial.

Just received a public report of snow mixed with rain up in Florence, in the northwest corner of the state. Temperatures are dropping into the mid and upper 30s, and I expect more reports of snow flakes before the night is over.

We note that Mt. Cheaha is down to 33 degrees, so some of the high terrain locations might even get a dusting if the lower atomsphere continues to cool. Still, we don't expect any big issues, but it will be interesting to see the reports of snow as they come in tonight...

The Wednesday afternoon web video is on the server:

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

Great article by Jason Simpson below this one... we often use those parameters without a good explanation. Very nice job.

Some light rain is now reaching the ground across north Alabama with temperatures in the chilly 40s... almost 20 degrees below normal for this time of the year.

Coming attractions:

*Sprinkles will remain possible through about midnight tonight, and a few snow flakes might mix in over the northern third of the state before ending. Moisture is very limited, so precipitation will remain light.

*Another clipper system will bring more clouds and the chance of a few sprinkles late tomorrow night and Friday morning. Same deal; simply not very much moisture to work with.

*Some weekend changes. Saturday still looks nice with temperatures nearing 60 degrees by mid-afternoon and a decent amount of sunshine, but it now looks like a surface cold front will slip through late Sunday afternoon, and we have introduced the chance of a few showers with this feature. Once again, the moisture will be shallow so rainfall amounts should be light and spotty.

*March 16-17 Storms: Our weather still looks rather wet and potentially stormy toward the middle and end of next week. The latest runs of the GFS suggest more of a heavy rain threat as opposed to a severe threat, but it is still too early to be specific.

Generally speaking the latter half of March looks pretty wet... which you expect this time of the year. March is normally our wettest month of the year...

There has been a lot of talk in the last few days about rain changing to snow tonight, and on first glance, there is a lot of merit to the idea; however, if you inspect the atmosphere closely and look at some general rules of thumb, the water “clears up” somewhat and it is easier to see why the chances of that happening are so low.

First of all, the 12Z (6:00 AM) weather balloon sounding from the Shelby County Airport shows the state of the atmosphere this morning before any precipitation began in the state. There are some general “critical thickness” values that we use to determine whether any precipitation should fall as rain or snow. A “thickness” is the vertical distance between two levels in the atmosphere, and those levels are identified by their pressure in millibars:

Rule of Thumb Today’s Observation
1000 mb to 500 mb rain/snow line = 5400 meters *5433 m
1000 mb to 700 mb rain/snow line = 2840 meters *2873 m
1000 mb to 850 mb rain/snow line = 1300 meters *1325 m
850 mb to 700 mb rain/snow line = 1540 meters *1548 m
850 mb to 500 mb rain/snow line = 4100 meters *4108 m

A layer’s thickness is directly related to the temperature of that layer. If the thickness is below the rule of thumb value, it is assumed that the layer is below freezing and would support frozen precipitation. In our case today, we started out above the rule of thumb values, so it is assumed that these layers of the atmosphere are warm enough to keep it all liquid.

But what about evaporative cooling? Guess what! There is another rule of thumb for that one too! It’s called the “One-third” rule. When the air is saturated, it is said to be at the “wet-bulb temperature.” You can get close to the wet-bulb temperature by dividing the number of degrees between the dewpoint and the temperature by three, and subtracting that amount from the actual air temperature (assuming that no warmer air is moving in! ) The temperature falls about 1/3 of the way toward the dewpoint, and the dewpoint rises 2/3 of the way toward the temperature. In our case today, it is obvious that some evaporational cooling is taking place because we have precipitation on the radar but no reports of precipitation at the surface. The amount of evaporative cooling today is not likely to be enough to drop the entire atmosphere below freezing.

Those are the two key factors in our forecast today. As you can see, it is very close, and there is still some chance that the factors could line up; it’s just not all that likely.

There are some other factors influencing this too. A surface low over Arkansas this morning is pulling in some warm air from the west, which is helping to melt anything that might be frozen. The upper air low over Arkansas is diving south-southeast instead of coming due east or a little south of east. That will take the greatest uplift and greatest chance of heavy precipitation (which could help lower those thicknesses! ) away from Alabama.

Hopefully that sheds some light on why we are so close to getting snow, but we are not too optimistic about it!



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Sure looks like we will me making the transition from a cold pattern to a story pattern across Alabama and the deep south during the latter half of March as the spring severe weather season really cranks up. Time to make a few points here as we all need to get ready for our big storm season:

*Every home and business in this state must have a NOAA Weather Radio. Sure, I know you get tired of me saying this, but seems like people are not listening. I figure less than five percent of Alabamians have a Weather Radio receiver in their home. Forget sirens, and remember we cannot help you when the TV is off, when you are watching a national satellite or cable channel, or when you are sleeping. Be sure all of your relatives understand this!

*E-Warn is a great service that sends warnings to cell phones, pagers, and computers. You sign up by county on the ABC 33/40 web site. Most of the time you get warnings within seconds. E-Warn is totally free, but keep in mind your cell phone provider might charge for each text message you receive. We have over 40,000 E-Warn subscribers across north and central Alabama. Sign up here:

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

*Our live Pinpoint Doppler Radar is now broadcast 24 hours a day, seven days a week on our digital channels, 5.2 and 9.2. If you have a digital TV receiver, give it a shot. The 5.2 signal covers Birmingham and points west, and 9.2 is for Birmingham and points east. Cable and satellite systems do not carry this multicast signal; you have to pick it up over the air on a digital receiver.

*Stay informed. Read the discussions here on this blog and our seven day discussion page.. We work long hours updating these sites and detailed information you won't get anywhere else. The more you now, the better off you will be!

The Wednesday morning web video is on the server:

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

Wow... J.B. Elliott posting at 3:11 a.m.! And people think I am the guy who gets no sleep.

Coming attractions:

*Our first northwest flow system rolls in here today with clouds, and a little scattered light rain. Probably not much more than a few sprinkles. Still can't rule out a few flurries from Birmingham north tonight, but no big deal.

*Wave number two arrives Friday with pretty much the same result; clouds and a few sprinkles. There is actually a third wave that will clip the northeast corner of the state Friday night, and you know the deal. A few sprinkles or flurries, mainly northeast of Birmingham.

*A moderating trend on Satuday with the mercury reaching the low 60s. BUT, the GFS showing a new solution for Sunday with a cold front slipping in here. The latest run at this moment, the 06Z run, puts the surface front in here Sunday evening. This could mean a few showers late Sunday or early Monday. And, it would put a lid on the warming trend for those two days. I will probably amend the seven day later today based on how the 12Z run looks.

*Still looks like a heavy rain or severe weather event here in the March 16-17 time frame as a strong wave moves this way from the west. Surface track now might suggest more of a heavy rain threat, but way too early for details.

The latter half of March looks stormy with a fast zonal flow setting up across the U.S. These are the busy days for sure!

I sure hope J.B. got a good nap this morning.

Places I would not want to be early on this Wednesday morning...

WORCESTER, MASS.
At 2 am, temperature 8, wind west gusts to 47 mph, wind chill -15

WEATHER BUOY OFF THE NEW ENGLAND COAST
At 2 am, Birmingham time, 23 degrees, west wind gusting to 57 mph with 14 foot waves. How would you like to be on a small, slow boat in that? The freezing ocean spray would make your boat look like a popcicle quickly!

MOUNT WASHINGTON, N. H.
Temperature 18 below, wind NW 98 mph, gusts to 109 mph, visibility 1/4 mile, wind chill 43 below.

DEADHORSE, ALASKA
Temperature 10 below, visibility 1/4 mile in snow, blowing snow, freezing fog, wind gusting to 46 mph, wind chill 43 below.

No thanks...I prefer my tiny corner of the world!