Good evening Texoma. Rain chances will be very high over the next 48-72 hours; we are going with 80-90% coverage. By Sunday afternoon, the majority of Texas and Oklahoma will have seen at least a drop of rain. Deep moisture is feeding northward from the Gulf of Mexico tonight which will help set the stage for heavy rainfall-some flooding is possible, especially south of I-20 in Texas.
This deep Gulf moisture will be in place as energy from once Hurricane Miriam moves across Texas, will aid in a large rain shield, with embedded thunderstorms, to develop across the west Texas and slowly push eastward. Rainfall rates will be high and some isolated locations could pick up 5-9" of rain! This is the latest map from the HPC, which shows near 100% coverage across the Southern Plains.
This graphic is in line with what much of the guidance is showing. This map may actually be slightly conservative for the Hill Country of Texas where the aforementioned 5-9" of rainfall could fall. Along with flooding, a few damaging wind gusts may occur with some of the storms Friday and Saturday; with that said it's a very low-end risk due to weak shear.
Rain chances will increase throughout the day Friday and through Saturday afternoon. By Sunday our rain chances will become lower, and shower coverage will be more isolated. A weak cool front will move through all of Oklahoma and into northern Texas on Sunday too, which should help taper rain chances across northern Texas and Oklahoma; rain will be confined to southern Texas at this point. Temperatures throughout this time-frame will be below average due to thick clouds and falling precipitation-mainly in the 80's on Friday with 70's possible on Saturday.
We will then pay close attention to the extended, 7-12 days, when a strong cold front looks to move through our area. This cool down will actually be partially related to Typhoon Jelawat. As Jelawat moves N/NNE and impacts Japan, it will force warm & moist air into the higher latitudes which in return the atmosphere will try to 'balance' this impact and send cold air southward into our neck of the woods. We will keep a close eye on this cold front as well as the rain chances over the next few days. We will have updates as needed.
(These thoughts are that of "Texoma Weather" and primoweather.com. For official information, please see www.nws.noaa.gov)