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Warm and dry weather will continue across Alabama today and tomorrow; we expect low 80s today, and mid 80s tomorrow. Some clouds will begin to show up tomorrow, but all of the big thunderstorm action will remain west of here. Much of mid-America is under a slight risk of severe weather today and tomorrow, in advance of a big upper low moving slowly out of the Southwest U.S.
THURSDAY: Parameters on the synoptic scale seem to be coming together for severe thunderstorms across the northern half of Alabama Thursday, and SPC has much of North and Central Alabama under a slight risk of severe weather. The GFS hints at surface based CAPE values around 1,500 j/kg, with 0 to 3 km helicity values soaring over 300 m2/s2 Thursday afternoon. The lack of a well defined surface boundary and the fact that the upper short wave will be weakening are two negatives, but everything else seems to be in place for a rough afternoon. The best chance of severe storms seems to be from about 2:00 p.m. until 10:00 p.m.
Rain amounts of one-half to one inch seem likely, but amounts will probably vary a good bit from town to town since thunderstorms will be involved, and initially they will be cellular.
Drier air moves into Alabama Friday, and at this point it looks like most of the state will be dry. We have mentioned a slight risk of an afternoon shower, but we might remove that later today if the 12Z model runs confirm the drying.
THE WEEKEND: The old surface boundary will be moving northward Saturday as a warm front, but with little upper support, rain does not look likely. The day will be warm and muggy, much like a summer day, and I think we have to mention at least a chance of widely scattered afternoon showers and storms simply because of the amount of instability that will be present (afternoon temperatures could approach 90 over West Alabama). But, much of the day should be dry, and rain should not be a major problem for outdoor events.
Sunday, however, looks wet at times and potentially stormy with another strong short wave passing just north of here. In fact, a number of severe weather parameters are showing up for Sunday, and we might have to deal with another round of strong storms. Lets get through Thursday’s event and we can focus on Sunday.
NEXT WEEK AND BEYOND: The first half of next week looks dry and cooler; the next significant weather system shows up at the end of the week, around May 16. Confidence beyond that is low due to the lack of run to run consistency.
WEATHER BRAINS: Don’t forget you can listen to our weekly 30 minute netcast anytime on the web, or on iTunes. This is the show all about weather featuring many familiar voices, including our meteorologists here at ABC 33/40. You can even listen here on the blog; look for the player on the top left. Scroll down for the notes for this week’s show, which was posted last night.
I will be speaking to the Greater Birmingham Postal Customer Council today at The Club… I will be back in the office early this afternoon and the next Weather Xtreme video should be up by 3:30. Enjoy the day!
