Prognostic Meteorological Discussion
Issued by NWS
Issued by NWS
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582 FXUS02 KWBC 120800 PMDEPD Extended Forecast Discussion NWS Weather Prediction Center College Park MD 400 AM EDT Fri Jun 12 2026 Valid 12Z Mon Jun 15 2026 - 12Z Fri Jun 19 2026 ...Heat to build over the West/Southwest early-mid next midweek... ...Heavy rain/flooding threat for The South early-mid next week... ...Overview... It remains the case that an unseasonably amplified pattern will be in place across the Continental U.S. from the weekend to well into next week as a mean upper trough consolidates over the central and eastern U.S. early in the period before slowly moving east later on. A leading/trailing frontal boundary is forecast to gradually sink across the south-central to southeastern U.S., focusing moisture for rain and thunderstorms. Rain could be heavy and lead to flooding concerns given a growing signal for deep influx of tropical moisture from the western Gulf. Upstream, upper ridging will build over the West through early next week, leading to hot temperatures that will be well above average in the Pacific Northwest. The amplified flow becomes more zonal later next week as heat focus shifts downstream across the south-central U.S.. ...Guidance/Predictability Assessment... Guidance continues to have a solid handle on the evolution of the mid-large scale upper pattern through most of the medium range period, featuring a West Coast/West ridge and reinforcement of a central to eastern U.S. trough. This amplified pattern may turn more zonal later next week as incoming shortwave energies potentially flatten the ridge while trough energies gradually lift out. A model/ensemble mean/machine learning guidance/manual blend offers a reasonable forecast basis with smaller scale spatial and temporal details mitigated as consistent with individual predictability. This solution seems in line with the National Blend of Models and offers reasonable WPC product continuity. ...Weather/Hazards Highlights... A potent and wavy cold front is forecast to slowly move southeast across the U.S. southern tier from late this weekend into next week, providing a focus for heavy rain and thunderstorms. Ample moisture and instability interacting with the generally west to east oriented front will mean an ample downpour/flash flooding threat is possible with the potential for repeat/training storms. The WPC Excessive Rainfall Outlook offers Marginal and Slight Risk areas for flooding over the South through early next week. Elsewhere, rain and thunderstorms are also possible from the Appalachians to the Eastern Seaboard into Monday along and ahead of the northern part of the front. Meanwhile, the back end of the front may produce some light to moderate rain over the Rockies and Four Corners states into early next week. A secondary front and shortwave energies could also bring some scattered showers and storms to the north-central Plains, Midwest, and Great Lakes early next week and may re-develop and expand/increase into next midweek given growing support in guidance to monitor. Cooler than average temperatures are likely underneath the upper trough and behind the cold front in the north-central U.S., spreading into the South and East as the week progresses while moderating. Meanwhile, the West will be rather warm under the upper ridge. The Desert Southwest can expect temperatures well into the 100s and perhaps over 110 into much of next week, with warmer than average temperatures extending into the central Great Basin. Above average temperatures should also be present in the Pacific Northwest early next week. Daily record highs could be broken as temperatures reach the 90s to perhaps 100 in the Willamette Valley and 80s farther north toward Seattle. Widespread Moderate to scattered Major HeatRisk is forecast for much of the West. Temperatures should gradually moderate in the Pacific Northwest, but above normal conditions will push east across the Intermountain West and reach the Plains and especially south-central areas midweek. 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 $$