The National Weather Service has issued a hazardous weather outlook for the entire region to highlight the risk for heavy rains and potential minor flooding, and damaging winds:
WITH A VERY MOIST AIRMASS ACROSS THE REGION…SCATTERED SHOWERS
AND THUNDERSTORMS WILL RE-DEVELOP TODAY AND TONIGHT…ESPECIALLY
DURING THE AFTERNOON AND EVENING HOURS. SOME OF THESE STORMS WILL
BE CAPABLE OF PRODUCING LOCALLY HEAVY RAINS IN EXCESS OF ONE
INCH…DAMAGING WINDS UP TO 45 MPH…AND OCCASIONAL CLOUD TO GROUND
LIGHTNING.MINOR FLOODING OF LOW LYING…POOR DRAINAGE AND FLOOD PRONE
AREAS…WILL BE POSSIBLE. MOTORISTS SHOULD BE ALERT FOR PONDING OF
WATER ON ROADWAYS…AND NEVER DRIVE THROUGH STANDING OR FLOWING
WATERS OF UNKNOWN DEPTH.
The NWS has also upgraded its forecast to call for an 80% chance of “heavy rain” today, with a 50% chance of storms tonight.
Lovely.
Radar indicates the remnants of a MCS currently moving into Middle Tennessee and progressing eastward. This thing is decaying, but there’s plenty of convection — heavy convection — behind it. And with diurnal heating, things are going to get cranking even more.
The Gulf is wide open, pumping rich low-level moisture into the entire Southeast. That is what is helping spawn these thunderstorms and rain showers that we’ve seen so much of the past few days. They’ve been scattered, but areas that have gotten them have seen the potential for a lot of rain in a short amount of time, hence the advisory from the NWS that some minor flooding is possible. Despite the heat, there hasn’t been enough instability to really crank out a lot of thunderstorms — upper-air support is limited — and so mainly all we’ve seen other than rain are a few rumbles of thunder here on the northern Plateau.
Whether that changes today, only time will tell. The Storm Prediction Center has all of West and Middle Tennessee under a slight risk for severe weather today. Models indicate fairly serious instability developing today, but little wind shear support, which should help to limit the severe stuff.
The latest outlook from the Hydrometeorological Prediction Center indicates the heaviest precipitation staying to our west. The latest GFS model and the latest NAM model both show the same, with the GFS indicating far more rain than the NAM. It’s worth noting, though, that all those models will struggle with the convective-type nature of the activity and won’t be especially reliable. Suffice it to say, though, that the potential is there for some moderate-to-heavy rain showers tonight in Gatlinburg.
The same will be true tomorrow as the rest of the state’s high school teams get set to kick off their seasons. With all this moist air flowing in from the Gulf of Mexico, things won’t change until we see a frontal boundary usher in a new air mass. That will happen late tomorrow or early Saturday, as a cold front will push through the region and drag in drier, cooler air behind it and put the damper on this rain activity.