Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
515 FXUS02 KWBC 291904 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 304 PM EDT Sun Jun 29 2025 Valid 12Z Wed Jul 02 2025 - 12Z Sun Jul 06 2025 ...A wet period is expected for parts of north-central Florida... ...Southwest to southern Rockies/High Plains monsoonal flow as the tropics activate over the eastern Pacific and Bay of Campeche... ...Guidance/Predictability Assessment... Model guidance, at least through the first half of the medium range period, remains in relatively good agreement which features an upper low exiting the Great Lakes and troughing being reinforced over the West Coast. 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. The affects how much a Central U.S. ridge gets eroded to the north, and 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 with some connection to Tropical Storm Flossie in the East Pacific. Some of the guidance is also hinting at leftover low pressure from a weakening frontal boundary over the Southeast, which may move across the Florida Peninsula or linger in the eastern Gulf. This system is being monitored for low probabilities of developing tropical characteristics, as shown by the latest Tropical Weather Outlook from the National Hurricane Center. The WPC forecast for today used a general model blend the first half of the period, increasing contributions from the ensemble means the latter half for increasing spread. This does maintain good continuity with the previous WPC forecast as well. ...Weather/Hazards Highlights... Thunderstorms with deep moisture/instability will bring heavy convective downpours ahead of a upper trough and surface front into mid-late week over the far Southeast U.S. where WPC Excessive Rainfall Outlook (ERO) Marginal Risk areas exist Day 4/Wednesday and Day 5/Thursday. A focus for multi-day heavy rains slowly shifts to Gulf coastal north-central Florida where a Slight Risk area continues for Day 5/Thursday given precursor rains and heavy rainfall potential given right entrance region upper jet support and anomalous Gulf moisture. Focus may shift southward over Florida late week/next weekend. Monsoonal moisture with some connection to eastern Pacific (TS Flossie) and Bay of Campeche (TS Barry) tropical features is likely to increase coverage and potential of rain amounts into mid- later this week into the Southwest and southern Rockies/High Plains on the western periphery of a warming central U.S. upper ridge. ERO Marginal Risk areas are in place there for Day 4/Wednesday and Day 5/Thursday. 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 offer a varied guidance signal to monitor for heavy rain/runoff potential to emerge more clearly out from the northern Rockies to focus locally over the northern Plains and Upper Midwest midweek into next weekend as upper trough/impulse energies work on moisture/instability pooling near wavy passing and draping fronts. Weekend activity with upper system/frontal progressions is slated to work into the central Plains and across the Midwest/Great Lakes. 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 (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 $$