Archive for July 21st, 2012
Widely Scattered Storms
Widely scattered showers continue across Central Alabama late this afternoon.
One healthy storm is over the City of Tuscaloosa. Others extend down into Greene County near Eutaw.
There is a cell in Shelby County, east of I-65 from east of Saginaw, Alabaster to east of Pelham. Another was just north of Columbiana.
Others are near Springville and approaching Pell City in St. Clair County.
If you are near on the storms, be alert for brief heavy rain and dangerous lightning.
Showers/Storms Starting to Form
Showers are starting to form across central Alabama this afternoon. There is even some lightning in the storm that has formed along the Bibb/Shelby County line between West Blocton and Montevallo. Everything, including this storm is moving north northeast in a generally southerly low level flow. We could be seeing a concentrated area of showers and storms forming generally in the I-65 corridor between Chilton and Jefferson Counties.
Factors involved in this afternoon’s forecast include:
1. A stationary frontal system near the Tennessee/Alabama border that is slowly fizzling
2. An upper level low over southern Mississippi and a surface low over southern Arkansas that is pulling moisture northward into South Alabama
3. Decent moisture levels in the I-20 corridor with preciptable water totals running around 2 inches (supportive of heavy rain). We are starting to already see this as mentioned above.
4. a good bit of clouds remaining over the area, limiting heating.
The early morning storms splitting left and right meant the US-78/280 corridor has been high and dry through the morning, which could prove interesting this afternoon for storm development. With leftover outflow boundaries to the left and right and untapped air in between, the corridor could see storms this afternoon. The lows to the west will pull moisture northeastward into Northeast Alabama, enhancing rain chances over there this afternoon.
The front will enhance rain chances over the Tennessee Valley.
The higher moisture in the I-20 corridor means scattered storms starting around mid-afternoon. We are already starting to see that. It is being enhanced a bit by energy that traveled southwestward from this morning’s storms over Northeast Alabama.
Look out for lightning and heavy rain from the storms that do form this afternoon. They could also produce strong gusty winds. Can’t rule out a couple of severe reports as well if any storms really get going. Keep this in mind for your outdoor activities.
Brian did a great job explaining affects on this afternoon temperatures in his post, which follows.
Temperature Challenges
In the morning Weather Xtreme Video, I noted that the temperature forecast was going to be a bit of a challenge today. Indeed, as James as noted many, many times and nearly all forecasters understand is that no area or region is a one number place. Today is an example of one of those days where that is painfully true!
This morning a large cluster of thunderstorms situated in the vicinity of Meridian kept morning lows in the rainy area around 70 or so. Clouds from that complex spread out affecting spots even where rain did not occur by holding temperatures in check. While some other spots, away from the clouds and rain, saw more sunshine. So the result?
Around 1 pm, temperature observations ranged from 79 at Meridian which saw a nice rain or around a quarter of an inch (less than I expected them to get) to 84 to 86 in the Birmingham area which saw the clouds but very little rain, to 90 degrees in the Montgomery area which saw mostly a sunny morning with just a cumulus field.
The temperature differences were somewhat more pronounced at the noon observations, but have smoothed out a bit at 1 pm as the clouds have become more uniform and the effects of the rain have moderated.
Now, as I noted in the morning discussion, will we see showers develop and how numerous? When you have a big complex in the morning like we saw this morning, it can sometimes stabilize the atmosphere enough to suppress any afternoon convection driven by the heating. It does appear that we will get getting some showers, isolated at the moment but there is still a long afternoon ahead – with showers developing in Bibb County, in East Central Alabama from Talladega to Anniston, and in extreme Northeast Alabama in Jackson County. Showers were moving slowly northward.
Also of interest was an area of scattered showers in Southeast Alabama also moving northward. Precipitable water values across Central Alabama were in the range of 1.8 to 2.1 inches and those values are likely to go up a bit with 850 millibar moisture transport from south to north.
-Brian-
Rumbles and Rainfall
A frontal system lying along the border between Tennessee and Alabama/Mississippi triggered late evening storms over Northeast Mississippi prompted late severe thunderstorm warnings around Tupelo, then weakened.
But they expanded greatly in coverage through the overnight hours as they took advantage of the squeeze between a weak surface low over southern Arkansas and big high pressure east of Florida. They bubbled up and then fed on leftover heat and moisture in their march toward the Gulf.
The eastern flank of these storms made it into western Alabama about 1:30 and spread increasing storms down the western counties of the state. Folks in
Marion, Winston, Walker, Lamar, Fayette, Tuscaloosa, Pickens and even Greene got a little early Saturday shake, rattle and roll, but nothing was severe.
Radar estimates indicated that parts of Pickens, Lamar and southern Marion Counties may have gotten two plus inches of rain. A larger area got between one and two inches. The rainfall quickly died as it approached I-59.
The Tuscaloosa Airport picked up only 0.13 inches. Meanwhile, Ronald Hughes in Coker got 1.72 inches! He is just five miles from the airport! Most of Ron’s rain fell in 45 minutes.
Poor Wallace Williams in Cottondale didn’t get a drop. Not a drop fell on most of McFarland or Skyland either.
NORTHEAST RAINFALL: Other storms formed this morning over Northeast Alabama. Vic Bell at Black Creek in northern Etowah County reports another 2 inches to go with the six he has already picked up this month. He would be happy to share with anyone who needs rain.
Morning Storms for Some
The latest edition of the ABC 33/40 Weather Xtreme Video is available in the player below. You can subscribe to the Weather Xtreme Video on iTunes by clicking here.
Some people across West Central Alabama waking up to the sound of rain falling along with thunder boomers. A large complex of thunderstorms was centered in the vicinity of Meridian, MS, moving generally southward with a scattered line of thunderstorms moving through parts of Central Alabama from Boaz to Tuscaloosa. Clouds and the morning storms will keep temperatures down again as we’ve seen a couple of times over the last week, however, if the sun breaks out, temperatures could climb to near 90. The additional moisture really should help most places stay in the 80s today. But humidity will be high.
Isolated wind damage is possible and additional thunderstorms could develop this afternoon. Sometimes the convection like this will stabilize the atmosphere enough that we don’t see additional storms, but as long as that weakness remains in the area aloft we cannot completely rule out additional storms this afternoon and evening.
The overall weather pattern does seem to be changing as the weakness in the upper atmosphere that has helped to generate numerous storms with some significant coverage to the rain areas begins to get pinched off as the upper ridge builds stronger. Without an air mass change, though, we will continue in a pattern with daily chances for showers and thunderstorms as the coverage diminishes to scattered or widely scattered. Daily chances for showers will be in the 20 to 30 percent range.
The ridge is the main feature to watch for the next week with highs climbing into the middle 90s. So while the heat cranks up a bit we still don’t see extreme heat for the next week.
The ridge does dampen somewhat by next weekend thanks to storm systems traveling across the US-Canadian border but the GFS keeps the ridge strong over the Southeast. I’m having a little trouble with that scenario as it seems more likely for the upper high to edge westward a little, but then we are verging on voodoo country. And as we are seeing this morning, the weather is likely to depend on small scale mesoscale boundaries.
Week 2 of the GFS modeling suggests a return to some unsettled weather as another weak trough sets up over the eastern US.
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Thanks for staying tuned to the Weather Xtreme Video. Stay with the Blog for additional updates on the weather for Central Alabama. I expect to publish the next video on Sunday morning by 8 am or so. Have a great day and Godspeed.
-Brian-
