Severe Weather Discussion for September 3 – September 9, 2007.
– Temperatures near or below normal all week.
– Chance of showers and thunderstorms much of the week.
– Tropics remain seasonably active with Felix and another tropical wave behind it.
– Severe Thunderstorms in Oklahoma: 10%
– Storm Chase: < 5%
– Winter Precip: < 5%
12z GFS is in reasonable agreement with prior runs concerning the next few days. A 588dm ridge will remain over the area, which is also responsible for the southern track of Felix. A weak closed low is located over western Texas this evening and this feature will move slowly northeast through late Wednesday. By this time period the weak closed low gets caught up in the mid-level, as a northern stream shortwave trof develops over the western U.S. Said trof will become the primary weather maker for the region through the weekend.
Models move the initial shortwave trof east-northeast across the northern states by Friday and develop a longwave trof over the central U.S. A strong shortwave trof is then proged to eject east out of the mean longwave position, which should bring a cold front through the region. Presence of tropical airmass due in-part to time of year and Henriette should lead to widespread showers and thunderstorms during the Friday through Sunday time area. Frontal timing is very iffy and bust potential is high since the frontal evolution will be dependent on the longwave trof evolution.
Presence of the current weak low and the expected cold front this weekend will keep precip chances in the forecast much of the week. This is not a flooding setup at this point, just 30%-50% chances during any given forecast period. Isolated severe thunderstorms are possible, but currently not expecting anything organized given weak flow aloft. Expected clouds and periodic rain should keep temperatures below normal with rain free days a little close to normal, currently 89F in OKC.
Hurricane Felix continues in the lower latitudes this evening and will probably impact Honduras/Belize. Another system is behind Felix and has some potential to develop as it moves west. GFS does try to develop the system off the Georgia Coast and then loops it back at the U.S. Not sure of this one, so we'll see.
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