Severe Weather Discussion for February 21 – 27, 2011.
– Severe thunderstorms are possible Thursday, mainly across east-central and southeast Oklahoma.
– Rain is possible Saturday evening into Sunday.
– Temperatures will be in the low 50s on Monday, upper 50s Tuesday, upper 60s Wednesday, near 70F Thursday, upper 40s Friday, and low 50s Saturday-Sunday.
– Severe Thunderstorms in Oklahoma: 20%
– Storm Chase: < 5%
– Winter Precip: 5%
Lead shortwave trof will continue to move across Kansas overnight as the rest of the upper system shifts east. A surface dryline was located across western Oklahoma this afternoon but is expected to remain dormant. A cold front will move through the state later tonight, bringing a temporary end to the unseasonable warm air. The surface high will shift east through Iowa allowing for return flow on Tuesday.
A southern stream shortwave is progged by the models to drop south along the California coast and turn inland just south of San Diego. This system will progress rapidly eastward into the region. As it approaches, return flow will increase late Wednesday into Thursday with upper 50s/low 60s dewpoints returning across the state. GFS/ECMWF indicate that this system will be a quick mover as it moves across Oklahoma on Thursday. Given the expected moisture and associated warm temperatures, severe thunderstorms are possible. I’m not as excited as SPC at this point, which seems to be polar opposite of normal situations. I won’t ignore the potential for a medium-end event, especially given impressive and seasonable wind fields. The best area appears to be east-central/southeast Oklahoma. However, 18z GFS has the dryline just east of OKC around noon, so development could occur near central Oklahoma early Thursday afternoon.
As this upper system shifts east, a cold front will move through the state. Models diverge significantly here with the GFS shifting the brunt of the cold air east and the ECMWF seemingly oozing cold air into the state. All of this as another system takes shape across the southwest U.S. Moisture will be nearby in south Texas and should attempt to return northward. Due to this potential, I went with rain across the state late Saturday into Sunday. Model differences lead into early next week as the GFS would point to additional thunder chances and the ECMWF a cold rain.
At this juncture I do not anticipate special discussions for Thursday, but I’ll continue to monitor the next few days. We’ll see what SPC does tomorrow morning.by