Happy Memorial Day Weekend Oklahoma! Please be safe out there and make sure you pay attention to the weather. There is a serious flash flood threat and also the potential for severe weather including tornadoes.
The upper level weather pattern this afternoon shows a deep trough of low pressure over the southwestern United States. Look more closely you can see two distinct short wave troughs / speed maxes within the over all trough. These are shown here highlighted in yellow. The first one over southeastern Arizona moves in Friday with widespread rain and thunderstorms developing as moisture is lifted up and over the cool drier air in place right now. This will make for an unseasonably cool and wet Friday. The second stronger jet max will round the base of the trough and swing east into the southern plains on Saturday. By this time all the low level gulf moisture will be surging north into Oklahoma to meet up with the upper air support. Thus rain, thunderstorms, flooding and severe weather will be possible Saturday depending on how it all sets up. The upper trough will be slow to shift east so that the threat for thunderstorms, flooding and severe weather will continue on and off into Memorial Day.
The pic above is the total rainfall forecast from the GFS weather model ending Monday morning. Again, all the action right here in the southern plains. The following pics below are shared from the National Weather Service in Oklahoma City and Tulsa. I basically agree with the forecast as it stands right now but you must understand that this forecast is not set in stone and we don't know the exact details just yet. I know it's going to rain but exactly where the heaviest rain sets up is still up in the air so to speak.
Bottom line more rain comes in tomorrow but the heaviest rain comes in over the weekend and the severe weather threat also increase over the weekend. Heavy rainfall with flash flooding, plus the threat for severe thunderstorms with large hail, damaging winds, tornadoes and dangerous lightning Saturday and Sunday. I don't know the exact details yet but hopefully as the system gets closer those crucial details will become clear. Be safe!