Major Flood Concerns, Severe Weather Also Possible
Major concerns for the overnight hours, through the day Saturday and for that matter through Saturday night center around what still looks to be a significant flood threat for much of NE OK as well as a severe weather threat. Notice there is very little change in the coverage of the flash flood watch as issued by the good folks at the local NWS office since yesterday. But keep in mind that heavy rainfall could occur most anywhere so those counties that are not currently included may need to be added as this is a very dynamic and evolving weather situation and there are always some surprises along the way.
Copious amounts of moisture are available for the approaching storm system to work with and since this will be a rather long lived event with multiple rounds of showers/storms, then the rainfall potential remains extreme. Notice the 2 day QPF continues to suggest more than 5" of total rainfall for much of NE OK. Keep in mind, this is an areal average and some locations could easily pick up much more than that. In other words, this system has the potential to set records for daily and monthly rainfall amounts for many locations and therefore poses a significant flood threat.
The most recent data runs continue to suggest a few storms forming during the early night time hours, but a more widespread line of storms forming to our west will be moving across the area during the late night hours. That would be followed by a brief break before another round of heavy showers and storms forms and moves over the area during the course of the day and at least one more round Saturday evening or night. With multiple rounds of storms, each with heavy rainfall, then widespread flooding will likely occur. Remember: Turn Around, Don't Drown.
There will also be a severe weather threat for tonight through the day Saturday with all modes possible. But, a complicating factor regarding the nature of the severe threat will be the position of a surface front that will be stalling out tonight and meandering around somewhat during the day Saturday before finally getting a shove on eastward by Sunday morning. The data runs continue to have considerable difficulty in resolving the location of that boundary with some putting it just NW of the I-44 corridor, others well SE of the I-44 corridor. In other words, the position could easily change by just a county or two and that would have tremendous implications regarding the local weather. Locations to the SE of the boundary will have gusty S/SE winds and temperatures well into the 70s, perhaps even briefly approaching 80 degrees. That means a much more unstable atmosphere and a greater likelihood of surface based storms that could produce a tornado. Locations north of the boundary will have a gusty N/NE wind and much cooler temperatures holding generally in the 50s or lower 60s. That reduces the tornado threat, but there will still be the potential for damaging winds and large hail. The location of that boundary will also provide a focus for the heaviest rains and therefore the greatest flood potential.
By Sunday, the upper level storm center will be ejecting to the NE and we will be on the backside with gusty W winds becoming more SW later in the day. There will also be some lingering light rain or drizzle to start the day and together with the cloudy skies all day long, it will be much cooler with temperatures holding in the 50s all day.
As you can see on our forecast page, the sun will finally come out on Monday and after a chilly start we should see a nice rebound in temperatures that afternoon. That will be followed by an even warmer day on Tuesday before another storm system moves through Tuesday night and Wednesday. This system will be moving through more quickly but will still bring another good chance of showers/storms along with another significant cool down.
In fact, temperatures will remain cooler than normal through the end of the week, although the latter part of the week should finally start to dry out. That trend looks to continue through the 8-14 day outlook as well with temperatures, on average, running below normal and not much in the way of any organized showers or storms as we head into the second week of May.
So, stay tuned and check back for updates.