Severe Weather Discussion for March 24 – 30, 2008.
– Temperatures near seasonable norms this week, with highs in the mid 60s Monday warming to the low 70s Tuesday – Thursday. A cool front should bring us back into the 60s for Fri-Sun.
– Severe thunderstorms are possible late Wednesday through Friday across much of Oklahoma and north Texas, as a cold front moves through the region.
– Severe Thunderstorms in Oklahoma: 25%
– Storm Chase: 10%
– Winter Precip: < 5%
Prior system resulted in a deep trof across the eastern U.S. While this trof is progressive it pulled a Canadian airmass through the region, resulting in an unseasonably cool day. The front is pushing Gulf moisture well out to see as the high moves through the southeast U.S. This combined with low amplitude flow across TX/OK results in little sensible weather through Wednesday. One big concern will be fire weather as western Oklahoma remains seasonably dry and vegetation dormant.
The real excitement for this week occurs as a low amplitude southern stream shortwave trof enters the northwest U.S. The resulting surface low will pull modified Gulf moisture into the region late Wednesday through Friday. Models have differing solutions as to what will happen, but they do agree on the basic pattern through Thursday. The GFS had been keeping a lot more energy in the northern jet stream resulting a closed low in southern Canada. The 12z run backed off on this feature and the model appears to be more inline with the ECMWF.
Isolated thunderstorms may occur late Wednesday along the developing dryline or even in Oklahoma as strong moisture advection occurs. GFS hints at some of this, but it is rather isolated. The dryline firms up and makes a run at Oklahoma/north Texas on Thursday as winds strengthen aloft in response to the incoming shortwave trof. OUN isn't that interested in Thursday, but it has my attention. First, 60-65F dewpoints will be in-place across Oklahoma, models show CAPE values around 2000 J/Kg and decent flow aloft. Synoptic scale lift will be lacking, but that doesn't mean storms won't develop. SPC has Oklahoma and north Texas in a Day 5 outlook and I certainly agree with this prog. GFS's frontal timing seems a little fast, but could be correct if enough cold air is tapped. Either way the front should clear the state on Friday and move into Texas. Showers and thunderstorms are possible along this feature.
After this system passes the atmosphere remains low amplitude for a few days. The GFS shows a weak southern stream shortwave trof moving into the southwest U.S. around Monday 03/31. Not sure about this, since consistency is low. Prefer to wait and see on this one.
While SPC's outlook for Thursday would hint at a moderate end event, I'm not so sure. I'm going to hold off on special discussion for now.
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