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National Weather Service
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
224 AM EDT Mon May 11 2026
Valid 12Z Thu May 14 2026 - 12Z Mon May 18 2026
...Guidance/Predictability Assessment...
Guidance seems reasonably clustered with the overall larger scale upper pattern from late week into the weekend as highlighted by a warming ridge that slides eastward into the Central U.S. as an amplified downstream trough shifts over/offshore the East. Noteably however, the greatest source of uncertainty continues to surround the upstream evolution and timing of a main closed low from the eastern Pacific to advance inland over the West then downstream along with advent of additional Pacific shortwave energies to subsequently drive less amplified flow later weekend into early next week. Models continue to especially struggle with the main Pacific closed low track/timing inland, with abysmal agreement both run-to-run and within the larger modeling suite as a whole and continuing with the latest 00 UTC guidance cycle. Even so, there was enough agreement overall to favor a composite of otherwise compatible GEFS/ECMWF/Canadian ensemble means through this forecast period. This plan seemed to best preserve WPC product continuity and maintain reasonable 01 UTC National Blend of Models integrity.
...Weather/Hazards Highlights...
It generally remains the case that an eastern Canadian closed upper-level low/trough will help support longwave troughing down over the eastern U.S. through late week. Impulses will lead to the progression of a wavy frontal systems and showers/thunderstorms through the East. System progression to the Atlantic will spawn moderate coastal cyclogenesis with wrapping moisture/rains lifting up/off the East Coast as a maritime threat. Troughing breaks down by the weekend as low amplitude ridging builds in from the west.
Upstream, an eastern Pacific closed low is slated, still with much uncertainty, to advance inland mid-late week to focus organized light to moderate precipitation most likely across portions of the northern Great Basin, Pacific Northwest, and northern Rockies. Surface lows and frontal boundaries will form downstream, bringing weekend shower/thunderstorm chances broadly from the central U.S. to the Midwest/Great Lakes/East. Farther upstream system energies with some showers will subsequently work inland into the West and downstream over the lower 48 with uncertain timing in an overall more benign weather pattern in increasingly zonal flow aloft.
Temperatures for the eastern U.S. will be below normal into late week before moderating with upper trough ejection to the Atlantic. Meanwhile, an eastward shifting upper ridge will gradually spread well above normal temperatures across the Central to East-Central U.S. that may produce several summertime high temperature records.
Schichtel