911
FXUS02 KWBC 062000
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
400 PM EDT Sat Jun 6 2026

Valid 12Z Tue Jun 09 2026 - 12Z Sat Jun 13 2026


...Significant heat wave will build over a large portion of the
central to eastern U.S. mid- to late next week...

...Severe weather and heavy rain threats possible in the northern
Rockies/Plains to Midwest...


...Overview...

An upper-level trough digging into the Northwest will likely be the
impetus of unsettled weather spreading across the northern Rockies
to northern High Plains, and severe thunderstorms across the
northern Plains through midweek. Moderate to locally heavy rainfall
should initially move across the east-central U.S. as the first
significant heat wave sets up Tuesday-Wednesday in the midsections
of the country, shifting/expanding into the eastern U.S. later
next week. Some storms/enhanced rainfall could set up across the
central Plain by late next week.


...Guidance/Predictability Assessment...

Much of the uncertainty remains centered around the speed of
ejection of an upper trough across the Northwest into the northern
Plains through the medium-range forecast period. Both the ECMWF and
CMC have favored a faster eastward ejection of the trough. The GFS
and GEFS have been slowly catching up to the ECMWF/CMC scenario,
with the 12Z GFS being the closest. The faster ejection of the
upper trough has led to an earlier onset of the heat into the
Midwest to upper Midwest, and earlier end to the heat through the
northern and central Plains. The faster trough ejection has also
led to an earlier onset of the heat in the Northeast and a higher
chance of the heat to intensify later next week from the Northeast
to the Mid-Atlantic.

The WPC medium-range forecasts are based on a consensus blend of
40% from the 00Z ECMWF/EC mean, 40% from the 06Z GFS/GEFS, and 20%
from the 00Z CMC/CMC mean. The blend for Days 6 and 7 is based
heavily on the consensus of the EC mean and GEFS mean, which avoids
the GFS` depiction of a tropical cyclone moving near the west of
Florida late next week.


...Weather/Hazards Highlights...

The shortwave moving from the Ohio Valley eastward combined with
the hot, humid airmass in place from the broader ridge aloft will
lead to thunderstorms capable of heavy downpours and flash flooding
on Tuesday. A Marginal Risk stretches from Lower Michigan through
parts of the Ohio and Tennessee Valleys in the Day 4/Tue ERO.
Scattered thunderstorms are forecast to shift slightly east into
the Appalachians on Wednesday, but upper-level support should be
lessening. Convection could spark in much the same area of the
eastern third of the U.S. into later week. Florida can also expect
daily, diurnally driven thunderstorms as a surface front settles
there.

An unseasonably strong low pressure system is forecast to push
across the northern Plains Tuesday-Wednesday and into south-central
Canada by Thursday, 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 risks of severe weather in the northern
Plains and Upper Midwest due to this potential. Meanwhile heavy
rainfall/flash flooding also looks to be a concern, and Marginal
Risks in the ERO are shown for this potential in the northern
Plains/Upper Midwest on Day 4/Tuesday, shifting somewhat east and
south on Day 5/Wednesday with the frontal boundary. More storms are
likely in parts of the Plains and Mississippi Valley into the
latter part of the week.

The upper trough in the West and multiple frontal passages will
bring cooler conditions and chances for scattered showers and
thunderstorms in the Pacific Northwest Tuesday-Wednesday. Guidance
has continued to hasten the eastward ejection of the upper trough
out into the northern Plains which results in a lessening chance of
heavy precipitation across western Montana through midweek but with
a broader swath of stratiform rain behind the exiting surface low.
Some snow is possible in higher elevations. Farther south, gusty
winds under the upper trough and very low relative humidity Tuesday
could produce conditions favorable for fire weather per SPC.

The amplifying upper-level ridge building over the central to
eastern U.S. is expected to bring the first significant heat of the
summer by mid- to late next week. The threat should gradually
shift from the central U.S. Tuesday and Wednesday towards the East
Coast by Friday and into next weekend. See WPC`s Key Messages for
more. Meanwhile, the upper trough over the western U.S. will lead
to some below average temperatures over the northwestern U.S.
eventually shifting into the northern High Plains and moderating.


Kong/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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