Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Wed Jun 19 2024 Valid 12Z Wed Jun 19 2024 - 12Z Fri Jun 21 2024 ...Significant heavy rain/flash flooding threat with gusty winds well ahead of Potential T.C. One expected to impact southern Texas today... ...A heat wave will persist over the Midwest, Great Lakes, Ohio Valley and the Northeast into late week... ...Thunderstorms and heavy rain become less active across the north-central today into Thursday but may reload across the northern Plains Thursday night/early Friday... With the last piece of the potent upper-level energy exiting into southern Canada, the weather across the northern tier states will be less busy than recent days. Meanwhile, Potential Tropical Cyclone One (PTC1) is making a headline as the heavy rain and tropical-storm-force winds well north of the center of circulation are poised to move onshore and head inland across southern Texas today. It appears that the lower and middle Texas coasts will be the locations that will most likely be impacted by the heavy rain and gale force winds. A coastal front may enhance the heavy rainfall just inland from the coast but how sharp this front will get is uncertain at this point. Meanwhile, the strong Bermuda High that will help sustain the heat wave across the Ohio Valley to the Northeast will also help steer PTC1 westward toward northern Mexico today as PTC1 could acquire tropical storm (TS) status before making landfall early on Thursday. The heavy rain well north of TS1 will likewise move west across southern Texas and into the Rio Grand Valley through tonight, resulting in rainfall totals of 5 to 10 inches from northeast Mexico into South Texas with maximum totals of 15 inches possible. Winds associated with TS1 will weaken rapidly over northern Mexico as the heaviest rainfall is forecast to move west of the Rio Grand Valley into northern Mexico and begin to taper off early on Friday. Meanwhile, some of the tropical moisture from TS1 is forecast to stream north and trigger showers and thunderstorms across the Four Corners region by Thursday and into Friday. As the aforementioned upper-level energy and associated low pressure system moves farther into Canada, the thunderstorms and heavy rain from the central Plains to the upper Midwest will become less active today. The trailing front from the low will become nearly stationary from west to east across the northern tier states during the next couple of days. The next piece of upper-level energy ejecting from the central Rockies will begin to interact with the stationary front late on Thursday and reinvigorate heavy rain and strong thunderstorms across the northern Plains and toward the upper Midwest into Friday morning. Meanwhile, a heat wave will continue to impact areas from the Midwest into much of the Ohio Valley, Great Lakes, Northeast and Mid-Atlantic through the next few days. Afternoon high temperatures and warm overnight lows will likely challenge daily records and even some monthly records. Heat index readings are expected to peak from 100 to 105 degrees in many locations. Those without access to reliable air conditioning are urged to find a way to cool down. Record warm overnight temperatures will prevent natural cooling and allow the heat danger to build over time indoors without air conditioning. Conditions are expected to improve over New England this weekend. Kong/Kebede Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php