Severe Weather Discussion for June 27 – July 3, 2011.
– Record setting high temperatures likely on Monday.
– Thunderstorms are possible late Monday into Tuesday for parts of Oklahoma, generally I-40 and north.
– Temperatures will be near 108F on Monday, upper 90s Tuesday, and 102-104F Wednesday-Sunday.
– Severe Thunderstorms in Oklahoma: 10%
– Storm Chase: < 5%
– Tropical Development: 5%
Models agree that a shortwave trof will push through the northern U.S. allowing a cool front to drift south into the area late Monday. Winds will likely veer ahead of the front as the surface low ejects northeast. Ongoing extreme drought in western Oklahoma and very warm 850mb temperatures will combine for a very hot day across parts of the state. As indicated in the morning OUN discussion, NAM appears to have a good handle on temperatures tomorrow with the GFS not even close. Pre-frontal compression ahead of incoming cool front will likely allow temperatures to surge ahead of this boundary. The all time June record high for OKC is certainly in jeopardy tomorrow. Additionally, OKC has hit at least 90F every day in June, the prior record is 27. This record is likely to be set on Tuesday. NAM MET data shows only 101F on Monday but think the best idea is to go much higher. Cold front hangs around in the state on Tuesday as southwest flow weakens, temperatures should be cooler although still well above the late June normal of 90F. Wednesday will likely see a return to triple digit heat as the ridge builds across the state. Models show 594dm thickness values a few times, supporting 100F or greater temps given extremely dry conditions across much of western Oklahoma.
12z GFS does show the ridge breaking down around July 4th with northwest flow, I’ll believe it when I see it! Since that is beyond this forecast period, not gonna worry. I’m not convinced on QPF for late tomorrow into Tuesday but NAM/GFS do have QPF across much of Oklahoma. Either way, amounts should be quarter of an inch or less, which in this drought means nothing.
GFS MOS is ignored throughout the week, as the model doesn’t get it. Even the ensembles struggle to bring OKC to 100F much of the week, although a few get it. NAM and ECMWF along with persistence is the best forecast. As such, I’m forecasting at least two records this week and may get a third. 1) record high for July 27th in OKC and 2) record number of days in June above 90F. The last one may-be the all-time June record high for OKC. If that is to occur, it will be the 27th.by