Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
245 PM EDT Mon Apr 20 2026

Valid 12Z Thu Apr 23 2026 - 12Z Mon Apr 27 2026

...Overview...

A fairly active and evolving spring pattern across much of CONUS
as a mid/upper-level low moves slowly across the northern Plains
late week, with troughing extending back into the West. This system
will bring strong winds across the West and Plains, with some
lingering rain and mountain snow into Thursday. As the trough and
its associated surface low interacts with surging Gulf moisture
over the central U.S., episodes of heavy rain and severe weather
will become more likely Thursday and Friday. The system will bring
periods of anomalous warmth ahead of it for the East and late-
season cool intrusions as below average temperatures expand from
the western U.S. to the central U.S. behind a strong eastward
advancing cold front.


...Guidance/Predictability Assessment...

The latest models and ensemble guidance remains in generally good
agreement on the large-scale pattern evolution, but with plenty of
uncertainty in the details. Models agree the core of the upper low
over the north-central U.S. should generally shift northward and
settle over south-central Canada before lifting northward next week
as it gets blocked by a ridge downstream. However, energy
distributed around it and ejecting out of the trough into the East
this weekend remains uncertain, and this certainty translates to
variations in rainfall coverage and intensity this weekend. Energy
surrounding this upper low and dropping down the west side of it
into the weekend and early next week are highly uncertain as well.
Despite differences in the guidance, its difficult to pick out any
one outlier solution. A general deterministic model blend seems to
work best for the first half of the period, transitioning to
majority ensemble means for Days 6 and especially Day 7. Generally
maintained good continuity with the previous WPC shift with the NBM
serving as a good starting point for the sensible weather grids.


...Weather/Hazards Highlights...

The upper low over the northern High Plains and eventually
settling in south-central Canada late this week will continue to
bring periods of low elevation rain and mountain snow into
Thursday, with locally heavy precipitation possible along favored
terrain. Accumulating snow will primary be confined to higher
elevations, with impacts limited to high mountain passes and
mountain towns. In addition, strong gusty winds are expected across
parts of the Rockies into the Plains.

This system will drive a cold front eastward across the Plains
into the Midwest and eventually the East. The cold front will
interact with warm Gulf moisture and an unstable airmass, which
will support a corridor of showers and thunderstorms across the
Plains into much of the eastern U.S. through the weekend. The
combination of the large scale forcing and increasing instability
along and ahead of a strengthening surface low and strong cold
front, will support widespread clusters of strong to severe
thunderstorms capable of producing heavy rainfall and isolated
flash flooding over the Central/South Plains and parts of the
Mississippi Valley. This flooding threat is highlighted by a
Marginal Risk in the Day 4/Thursday ERO. Given increasing soil
moisture from previous bouts of convection, an upgrade to a Slight
Risk is not out of the question in future updates. As the front
moves further east, the flood risk shifts into the Ohio/Tennessee
Valley on Friday. This flooding threat is highlighted by a Marginal
Risk in the Day 5/Friday ERO.

The front may settle and be slower to move across the Southeast
into this weekend, with a possible redeveloping weak area of low
pressure along the front. This will keep a shower and thunderstorm
threat across the south-central Plains to Tennessee Vally to
Southeast through the weekend, with locally heavy rainfall and a
flooding threat to monitor.

Below normal temperatures over much of western U.S. will expand
east into the Northern/Central Plains and Rockies by the end of the
week and parts of the Mississippi Valley by the weekend. Parts of
the Northern Plains/Rockies will drop to 15-20 degrees below
normal, where highs will be in the 40s over the northern Rockies on
Thursday and will gradually spread into the Northern Plains by
Friday. Ahead of the frontal system, above average temperatures
will persist through Friday across parts of the central U.S. into
much of the eastern U.S. before temperatures moderate into the
weekend. Over the Pacific Northwest, temperatures will begin to
trend slightly above average late in the period as upper level
ridging sneaks into the region.


Santorelli/Oudit


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