291 FXUS02 KWBC 011859 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 259 PM EDT Tue Jul 1 2025 Valid 12Z Fri Jul 04 2025 - 12Z Tue Jul 08 2025 ...Heavy Rain/Flash flooding threats for both Florida Peninsula and the north-central Plains/Upper Midwest through Friday/Saturday... ...Hazardous heat and humidity expected to spread from west to east across the northern tier states through the holiday weekend... ...Pattern Overview... Amplified upper troughing over the Northeast will lift out over the upcoming holiday weekend as multiple Pacific shortwaves dig into a West Coast mean upper trough which will help to keep it in place heading into next week. In between, a building upper ridge will spread a threat of hazardous heat from west to east across the northern tier states this holiday weekend into early next week. Meanwhile, a continued series of strong to severe convective forcing and local heavy rain fueling impulses and fronts will progress atop/around the ridge from the north-central U.S. to the Midwest into the Northeast. Meanwhile, tropical moisture appears to linger near a slow-to-dissipate stationary front across the Florida Peninsula through the holiday weekend. ...Guidance/Predictability Assessment The WPC medium range product suite was derived from a composite blend of deterministic and ensemble guidance from the 00Z ECMWF/EC mean, 06Z GFS/GEFS, 00Z CMC/CMC mean, along with the National Blend of Models. As forecast spread and uncertainty increase over time within average seasonal norms, the blend leans heavily toward the ensemble means by the end of the forecast period for early next week. WPC continuity is well-maintained. ...Weather/Hazards Highlights... Thunderstorms within deep tropical moisture and instability will support heavy convective downpours along/south of a lingering and slow-to-dissipate front across Florida through the upcoming holiday weekend. WPC Excessive Rainfall Outlook (ERO) Marginal Risk areas are in place for Day 4/Friday and Day 5/Saturday in a region across west-central Florida Peninsula preceded by heavy rains and anomalous Gulf tropical moisture. Latest guidance has continued to back off on explicit QPF amounts despite a favorable pattern feeding off the eastern Gulf where the NHC has been monitoring for the potential of tropical cyclone formation. Monsoonal moisture with some connection to current eastern Pacific Hurricane Flossie and some Gulf moisture from recent Barry may boost rain potential that may linger into Friday over the Big Bend and vicinity. Model guidance has generally backed off on the QPF amounts. Periodic afternoon and nocturnal strong to severe storms/MCS activity offer heavy rain/runoff potential to focus from the north-central Plains to the upper Midwest late week into Saturday as upper trough/impulse energies work over the northern periphery of the main central U.S. upper ridge where moisture/instability tends to be lifted near a wavy draping front. WPC ERO Marginal Risk areas have been maintained for Day 4/Friday and Day 5/Saturday. From the weekend to early next week, showers and embedded thunderstorms could refire across the north-central states where ejection of upper-level shortwaves from the northern Rockies will interact with the wavy frontal zone which could lead to locally enhanced rainfall in portions of the northern High Plains to the northern Plains. Meanwhile, a wave of heat and humidity is expected to spread from west to east across the northern tier states including the Ohio Valley and mid-Atlantic through the holiday weekend around the upper ridge. Kong/Schichtel Additional 3-7 Day Hazard information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php WPC medium range 500mb heights, surface systems, weather grids, quantitative precipitation forecast (QPF), excessive rainfall outlook (ERO), winter weather outlook (WWO) probabilities, heat indices, and Key Messages can be accessed from: https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml https://www.wpc.ncep.noaa.gov/#page=ero https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4 https://www.wpc.ncep.noaa.gov/heat_index.shtml https://www.wpc.ncep.noaa.gov/#page=ovw $$