559
FXUS02 KWBC 070755
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
355 AM EDT Sun Jun 7 2026

Valid 12Z Wed Jun 10 2026 - 12Z Sun Jun 14 2026


...Significant heat wave will build across the central U.S. midweek
and shift into the East late week...

...Severe weather and heavy rain threats possible in the Midwest...


...Overview...

An upper trough will be atop the northern/central Rockies as the
forecast period begins midweek. The eastern side of the trough will
push a front east into the northern Plains and Midwest, providing a
focus for heavy rain and potentially severe thunderstorms there.
The frontal system is forecast to continue pressing east across the
northern tier, but could stall across the central U.S. into late
week and cause additional rounds of thunderstorms in the central
Plains/Mid-Mississippi Valley. Meanwhile, a mean upper ridge is
forecast to take hold ahead of the trough, leading to well above
average temperatures/heat indices in the central U.S. midweek and
pushing into the eastern U.S. late week and over the weekend, for
the first significant heat wave of the summer in many areas.


...Guidance/Predictability Assessment...

Model guidance is generally agreeable with the upper trough axis
over the Rockies midweek, along with the associated surface
low/frontal system(s) in south-central Canada and the north-central
U.S. ahead of it. The trough is forecast to lift a bit as it moves
east, and the timing for it and its front to eject east have been
more stable amongst recent model runs. However, upstream energies
coming into the back of the trough in the Northwest have been less
certain, especially by next weekend. After the 12/18Z guidance
mostly showed vorticity feeding into the trough across the northern
High Plains and vicinity, the more recent 00Z models have
generally favored a shortwave more in the Northwest. This keeps a
building ridge mostly more offshore in the eastern Pacific. Will
continue to monitor model trends as this affects sensible weather
like temperatures in the Northwest.

The WPC forecast was able to use a multi-model blend early in the
forecast period. Increased the proportion of ensemble means through
the period amid growing uncertainty, with the means over half the
blend by Day 7. This model blend also worked well for the southern
to eastern mean upper ridge (and the embedded shortwave traversing
through it mid- to late week).


...Weather/Hazards Highlights...

Unseasonably strong surface low pressure is forecast to push
across the northern Plains and south-central Canada into midweek,
ahead of the northwestern U.S. trough. Fronts with the low will
help focus convection and plentiful moisture, instability, and
shear will be in place. The Storm Prediction Center is calling for
a risk of severe weather in the northern Plains and Upper Midwest
due to this potential on Wednesday. Heavy rainfall/flash flooding
also looks to be a concern. A Marginal Risk is indicated for the
Upper Midwest with the potentially severe convection. Farther
south, return flow in the form of a strong low level jet could
bring ample moisture and instability into eastern Kansas into the
Mid-Mississippi Valley for the evening and overnight hours
Wednesday night. Dependent on the upper-level trough evolution,
strong energy aloft for forcing may be in place, as well as the
surface front. The Marginal Risk extends to that region as well,
but a Slight Risk upgrade and QPF increases may be necessary in
future cycles. Into Thursday, the front should continue slowly
southeastward in the central U.S. ahead of the upper trough,
sparking additional thunderstorms. A Marginal Risk stretches from
western portions of the Ohio Valley across the Middle Mississippi
Valley and south-central Plains for the Day 5/Thursday ERO. More
rounds of thunderstorms are likely in parts of the Plains and
Mississippi Valley into the latter part of the week.

Shortwave energy over the Appalachians and vicinity midweek,
combined with the hot and humid airmass in place from the broader
ridge aloft, will lead to thunderstorms across eastern parts of the
Ohio Valley into the Appalachians, possibly spreading into the
Mid-Atlantic Thursday. So far this looks to remain below a 5
percent chance for excessive rainfall/flash flooding especially as
the support aloft weakens. Scattered thunderstorms are forecast to
continue into late week and the weekend in much of the East.
Florida can also expect daily, diurnally driven thunderstorms.

The upper trough in the West and multiple frontal passages will
bring cooler conditions and chances for rain in the Northwest into
Wednesday, along with potential snow in higher elevations of the
northern Rockies. Into late week and next weekend, the details of
the trough are more questionable, leading to uncertainty in
additional rounds of rainfall across the northern Rockies/northern
High Plains.

The mean upper-level ridge over the central to eastern U.S. is
expected to bring the first significant heat of the summer by mid-
to late week, as temperatures soar 10-20 degrees above average. The
threat should gradually shift from the central U.S. Wednesday
towards the East Coast by Friday and into next weekend. See WPC`s
Key Messages for more. Meanwhile, the upper trough over the
Northwest will lead to some below average temperatures in that
region for midweek, then shifting into the northern Plains and
moderating. The West Coast should see a warmer trend by next
weekend, but how warm the region will get is questionable due to
model differences.


Tate


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




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