Preliminary Forecasts
Issued by NWS
Issued by NWS
588 FXUS02 KWNH 300709 PREEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 308 AM EDT Mon Jun 30 2025 Valid 12Z Thu Jul 03 2025 - 12Z Mon Jul 07 2025 ...Multi-day Heavy Rain/Flash flooding threat for Florida... ...Southwest U.S. to southern Rockies/High Plains monsoonal rains as the tropics activate over the eastern Pacific and the Gulf... ...Northern Plains/Upper Midwest Heavy Convection/Rain threat... ...Guidance/Predictability Assessment... Guidance through the first half of the medium range period for Thursday into Saturday remains in relatively good agreement. For the second half of the period, the most pronounced differences remain with the handling of northern and southern stream energy differences from the Pacific to the West Coast and inland. This affects how much a warming Central U.S. ridge gets eroded to the north and with smaller scale mesoscale systems riding the top of the ridge. One thing that has been consistent is the guidance continuing to show an increased signal for monsoonal flow into the Southwest Thursday into Friday with some connection to Tropical Storm Flossie in the East Pacific off Mexico and T.D. Barry out from the Gulf. Some guidance is also hinting at leftover Gulf low pressure from a weakening frontal boundary out from the Southeast U.S. may impact the Florida Peninsula by later this week. This system is being monitored with low probabilities of developing tropical characteristics by the National Hurricane Center. Accordingly, the WPC forecast used a model blend the first half of the period Thursday/Friday before transitioning Saturday into a GEFS/ECMWF ensemble solution later weekend into early next week amid increasing forecast spread. This plan maintains good product continuity with the previous WPC forecast and is overall in line with a composite of machine learning and 00 UTC guidance. ...Weather/Hazards Highlights... Thunderstorms with deep moisture/instability will bring heavy convective downpours ahead of a upper trough and surface front into late week for the far Southeast U.S./Florida where WPC Excessive Rainfall Outlook (ERO) Marginal Risk areas exist Day 4/Thursday and Day 5/Friday. A focus for multi-day heavy rains may work to Gulf coastal central Florida where a Slight Risk area continues for Day 4/Thursday and Day 5/Friday given precursor rains and heavy rainfall potential given initial right entrance region upper jet support and anomalous Gulf tropical moisture. Focus may shift slowly southward over Florida over the weekend. Monsoonal moisture with some connection to eastern Pacific (T.S. Flossie) and Bay of Campeche (T.D. Barry) tropical features is likely to increase coverage and potential of rain amounts into later this week into the Southwest and southern Rockies/High Plains on the western periphery of a warming central U.S. upper ridge. A ERO Marginal Risk area is in place there for Day 4/Thursday, slowly shifting focus to the far southern High Plains Day 5/Friday. Areas like the Sacramento Mountains, where the steep terrain and burn scars cause the area to be particularly sensitive to rain and most vulnerable to potential flash flooding, especially with wet antecedent conditions there. Elsewhere, periodic afternoon and nocturnal strong to severe storms/MCS activity offer heavy rain/runoff potential to focus over the north-central Plains and Upper Midwest late week into Saturday as upper trough/impulse energies work over the northern periphery of the main central U.S. upper ridge as moisture/instability pools near wavy passing and draping fronts. WPC ERO Marginal Risk areas have been introduced for Day 4/Thursday and Day 5/Friday. Weekend to early next week activity with upper system/frontal progressions then work over the central Midwest/Great Lakes and the Northeast. 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 $$