You can tell summer is getting closer; we are beginning to have some air quality problems in the Birmingham metro area. Yesterday’s AQI (air quality index) was 112, which is considered unhealthy for sensitive groups, like people with heart or lung disease, older adults, and children. The primary pollutant was particulates, with the highest concentration showing up at the North Birmingham air monitoring site. A very similar weather setup will be in place today, and ADEM and the Jefferson County Health Department have issued a code orange alert for today, meaning air quality is expected to be unhealthy again for sensitive groups.

As we get into the warmer summer months, air quality deteriorates in the Birmingham metro area (Jefferson and Shelby counties) and often ground level ozone is an issue on hot days with little wind. Air quality and ozone alerts are based on a color system: green means good air quality, yellow means moderate air quality, orange means unhealthy air quality for sensitive groups, red represents unhealthy air for all of us, and purple suggests very unhealthy air quality. I have never known Birmingham to have a purple air quality day, thank goodness!

On orange and red alert days, we all can take actions to help improve air quality, like setting the thermostat a few degrees higher, reducing the number of trips you take in your car, avoiding drive through-windows during the middle of the day, and mowing the lawn late in the day as the sun is setting. The biggest help is getting cars and trucks off the road during the peak of the daytime heating process. We tend to have the largest number of air quality alerts in July and August, but it can be a problem anytime between now and October! We will keep you posted on air quality alerts here.

The Tuesday afternoon web video is on the server:

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

We are still looking at a sharp change to cooler weather by the weekend...

TOMORROW: Dry and warm weather will continue, with temperatures topping out around the 80 degree mark in most places. Lots of sunshine through scattered high clouds.

THURSDAY/FRIDAY: The models bring moist air into the state on Thursday, and showers could begin to form during the afternoon as a cold front approaches. A few passing showers and storms are likely Thursday night into Friday as a wave of low pressure forms on the front over Tennessee. The latest QPF guidance is suggesting about one inch for Birmingham.

THE WEEKEND: Looks like the sun will return on Saturday, but the weather will be windy and much cooler. Highs in the low to mid 60s with a cool northwest wind. Then, by Sunday morning, temperatures should drop into the 34 to 42 degree range over much of north and central Alabama. We are using 39 in our forecast for now, and will make adjustments as we get closer to the weekend. Still looks like some light frost is likely in the colder valleys and protected areas.

NEXT WEEK: A storm system over the plains will bring rain and storms back to Alabama by Monday night and Tuesday. I still don't think the air will have time to recover from those upper 30s Sunday morning... so severe weather doesn't look very likely to me at this time.

Beyond that, the 12Z run of the GFS is totally different from the 00Z run. No big time, phased eastern U.S. trough, which would mean no cold snap for the middle of next week. But, I don't believe just one model run, so no change in thinking at this point.

Looks like an active southern stream setting up as we get into May, which means our weather will probably become wetter and stormy at times.

AIR QUALITY: I notice the Health Department has an air quality alert for the Birmingham metro area today... guess it is that time of the year! Summer must not be too far away...

The Tuesday morning web video update is on the server:

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

Wow.. looks like we have potential for record cold across much of the eastern U.S. not once, but twice during the rest of April. And, the GFS MOS is now spitting out 34 degrees for Birmingham Sunday morning! Lets look at everything in a time line fashion:

*NEXT TWO DAYS: Dry and mild weather continues today and tomorrow with a partly sunny sky each day and afternoon temperatures peaking in the 78 to 82 degree range.

*THURSDAY/FRIDAY: The models are faster now in moving showers into Alabama in advance of the first cold front, and I will now include showers as early as Thursday afternoon. Still looks like the best chance of showers, and possibly a thunderstorm, will come Thursday night into Friday as a surface wave forms on the front over Tennessee. Rain amounts of one-half inch look like with this front, and I still do not expect any severe weather problems.

*THE WEEKEND: We should be dry on Saturday and Sunday, but temperatures will be much cooler. Highs drop into the 60s, and we won't go overboard Sunday morning right now, but upper 30s are certainly possible with the chance of some scattered frost in the colder valleys. The record low for Sunday (April 24) is 35 set in 1986; we might be close. I will be dropping our forecast low for Sunday morning to 39 degrees; but we all know this is not a "one number" place. Lows Sunday morning will vary from 34 to 42. And, keep watching for more changes as we get closer to the weekend.

*NEXT WEEK: Now the GFS is showing a pattern that looks like a severe weather setup by Monday night or Tuesday. A deep surface low northwest of Alabama with nice upper support. However, I really doubt if we can get quality unstable air in here that soon after reaching the upper 30s Sunday morning. One way or another, a few showers and storms are likely, and then yet another cold air shot arrives for the middle of next week.

We might be dealing with 30s again, and the risk of some frost by Wednesday or Thursday morning of next week, April 27-28. Hard to be specific this far out, but growers will need to pay attention to the numbers.

We have never had a freeze in Birmingham beyond April 23. It will be very interesting to see how this all plays out!