Preliminary Forecasts
Issued by NWS
Issued by NWS
860 FXUS02 KWNH 040628 PREEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 227 AM EDT Fri Jul 4 2025 Valid 12Z Mon Jul 07 2025 - 12Z Fri Jul 11 2025 ...Coastal Southeast heavy rain threat as NHC eyes system.... ...North-central U.S. to Midwest/Northeast heavy rain threats, with trailing activity spread back to the south-central states... ...Hazardous heat and humidity to spread from the Midwest this holiday weekend to the Mid-Atlantic/Northeast early next week as sweltering heat lingers for the South and builds over the West... ...Pattern Overview... An area of low pressure located offshore near Jacksonville, Florida is being closely monitored by the National Hurricane Center as the environment is marginally conducive for further development into a tropical or subtropical. This feature is expected to bring heavy rains to portions of Florida today and to the Carolinas by Saturday. Pacific shortwaves will work into lingering West Coast mean upper troughs into next week. A building upper ridge downstream will spread a threat of hazardous heat and humidity from the Midwest this holiday weekend to the Mid-Atlantic/Northeast early next week as a hot summer airmass lingers over the South and also builds next week up over the West. The Southwest will likely have renewed monsoonal moisture across the region. A series of strong to severe convection and heavy rain fueling impulses will progress atop the ridge from the Midwest/Great Lakes to the Northeast, with trailing activity also firing back over the north-central and south-central U.S. ...Guidance/Predictability Assessment The latest suite of guidance maintains good agreement through the first half of the extended with the increasing spread for the latter periods. Confidence remains high for the pattern in regards to widespread heat and moderately high for the duration of the most extreme heat. The WPC medium range product suite was mainly derived from a blend of GFS/CMC/ECMWF/UKMET along with the GEFS and ECMWF ensemble means and the National Blend of Models. The development and track of the potential tropical system offshore the Southeast U.S. coast will be critical to monitor. ...Weather/Hazards Highlights... WPC Excessive Rainfall Outlook (ERO) Marginal Risk areas have been added for Day 4/Monday and Day 5/Tuesday for the coastal Southeast and southern parts of New England given the increased moisture and rainfall potential associated with possible system development that the NHC is monitoring. A broadening upper ridge will spread hazardous heat and humidity from the Midwest to the Mid-Atlantic/Northeast over the weekend and into next week while the hot airmass remains over the South and builds to the West. Monsoonal moisture coming into the Southwest along with daytime heating will trigger showers and thunderstorms development which are covered by a Day 4-5 Marginal Risk area. A slow main frontal push across from the Great Lakes/Ohio Valley states and the Northeast may focus periods with enhanced pooled moisture and instability to fuel some strong to severe storms and locally heavy rain/runoff threats with training potential in spots Sunday into Monday as upper trough/impulse energies work on the northern periphery of the main central U.S. upper ridge. Trailing activity extends back next week with impulses over the south- central U.S. and into the Southwest with some renewed monsoonal flow. Elongated WPC ERO Marginal Risk areas are depicted for Day 4/Monday and Day 5/Tuesday. Convection/MCS activity will also fire back to the north-central states next week as subsequent upper- level waves interact with moisture/instability pooling fronts/upper diffluence. A Day 5/Monday marginal risk area was maintained there. Campbell/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 $$