660 FXUS02 KWBC 201828 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 228 PM EDT Mon Jul 20 2026 Valid 12Z Thu Jul 23 2026 - 12Z Mon Jul 27 2026 ... Heavy Rainfall threat focus for the Eastern Carolinas and for Central to Western Gulf coast areas with Tropical System "Two"... ...Hazardous Heat over the South-Central U.S. this week to shift to the West-Central and northern U.S. into next week as ongoing monsoonal rains over the Southwest/Intermountain West/Rockies tend to ease... ...Overview... Hot and moist conditions will linger over the South-Central U.S. this week outside the influence of Tropical Depression Two. Meanwhile, northern tier shortwaves working into an upper trough position over the East and moderating surface fronts will bring rounds of locally heavy rains later this week down over the eastern Carolinas with a slow moving and moisture pooling front. Activity to work westward over the Gulf Coast and into Texas will be fueled by tropical system "Two" development, track and deep moisture. Elsewhere, ample monsoonal moisture now streaming from the Southwest and Intermountain West/Rockies into the Plains will fuel enhanced showers and thunderstorms. Heat and upper ridging over the southern Plains will shift northward over the Plains and to the Southwest/Rockies. Monsoonal flow may ease later in this period with this transition. ...Guidance/Predictability Assessment... Latest guidance continues to show good agreement on the large scale pattern through the entire period featuring a large upper ridge that builds over the intermountain west/central U.S. in response to a reloading Eastern ridge. There are some uncertainties on the individual shortwaves as they drop into the trough, and any sensible weather/QPF impacts associated with them. Still a lot of uncertainty associated with TD Two, which is forecast by the NHC to strengthen into a Tropical Storm before the medium range period. There is question on how much of a reflection is left after it crosses far southern Louisiana during the short range, and how much moisture may reach the coast. Many of the models keep heavy rainfall off the coast, but did edit the manual WPC grids to bring some rainfall towards central and western Gulf, consistent with continuity. The WPC 500s/fronts were based on a blend of the deterministic guidance through Day 5, increasing to 40 percent of the ensemble means with 60 percent deterministic by Day 6 and 7. ...Weather/Hazards Highlights... Flow around a main upper ridge will continue to draw significant monsoonal moisture into the Southwest and Intermountain West/Rockies this week, but may ease this weekend/early next week. Moisture will fuel scattered to numerous showers and thunderstorms with potential to produce heavy rainfall and localized flash flooding. Sensitive places such as burn scars, steep terrain, etc., would be the most vulnerable to possible flooding concerns. Marginal Risks of excessive rainfall span the Southwest and Intermountain West/Rockies to the central Plains/Mid-Mississippi Valley Thursday and Friday, with small embedded Slight Risk areas for the central Plains/Mid-Mississippi Valley where convection may focus. Upper ridge/closed high influence over the south-central U.S. offers Major HeatRisks this week as temperatures upwards to 5-10F above already hot averages combine with high humidity. Expect spotty record highs and more widespread record overnight lows to limit relief. Heat indices rise rise upwards to 105-110+F in some spots, with focus expanding up through the Plains and into the Southwest/Rockies this weekend/early next week. Elsewhere, heavy rains/convection are forecast to focus down into the eastern Carolinas/Southeast later week given support aloft and slowed frontal push. WPC Excessive Rainfall Marginal Risk Thursday and Friday also have embedded eastern Carolinas Slight Risk areas. Meanwhile to the South, Tropical Depression "Two" is forecast to reach Tropical Storm strength while tracking westward near the central Gulf coast towards Texas into later this week. Deep tropical moisture associated with this system may fuel at least a localized threat for heavy rain/runoff issues. A Marginal Risk area with an embedded Slight Risk area is in place from northern Florida/Gulf Coast into eastern Texas Thursday and Friday. Santorelli/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, excessive rainfall outlook, winter weather outlook probabilities, heat indices and Key Messages are at: 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 $$