218
FXUS02 KWBC 052047
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
447 PM EDT Fri Jun 5 2026

Valid 12Z Mon Jun 08 2026 - 12Z Fri Jun 12 2026

...Heavy rainfall threats expected to evolve over the Mississippi
to Ohio Valley early to mid next week and northern Rockies mid- to
late next week...

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

...Overview...

Embedded upper-energy within an amplifying ridge over the central
to eastern U.S. will support scattered to widespread thunderstorms
over the Mississippi/Ohio Valleys early next week with a heavy
rainfall/flash flood threat. This upper-ridge will also bring the
first significant heatwave of the Summer to much of the central to
eastern U.S. next week. Meanwhile, a deep upper-trough over the
western U.S. will bring cooler, unsettled conditions to the Pacific
Northwest and northern Rockies, with a trend towards heavier
rainfall into the northern Rockies by mid- to late week. A severe
weather/flash flood threat is also expected into the northern
Plains/Upper Midwest mid-week as this upper-trough shifts eastward
and helps to spin-up a strong low pressure/frontal system at the
surface.


...Guidance/Predictability Assessment...

Latest 00/06Z model guidance remains reasonably well clustered
through most of the period as the pattern transitions next week to
become more amplified with mean upper-ridging over the central to
eastern U.S. and mean upper-troughing over the central to western
U.S. Guidance also has a good handle on an initial shortwave
rounding the ridge through the Midwest/Ohio Valley early next week
which will likely trigger heavy rainfall given the very warm, moist
airmass that will be in place. Additional upper-energy(s) within
the mean upper-trough should eventually begin to impinge on the
upper-ridge by mid- to late next week with a potentially
significant accompanying surface system over the northern
Plains/Upper Midwest lifting into Canada. The latest deterministic
guidance shows the deepening surface low potentially reaching the
low 990s to mid 980s mb. Guidance begins to diverge a bit more on
the track and eventual progression of an accompanying surface cold
front which renders temperatures and precipitation forecasts over
the northern/central Plains into the Midwest rather tricky, but the
potential for impactful severe weather/heavy rainfall is notable.
With a prominent upper-ridge in place above average/hot weather is
expected over much of the eastern U.S., though there is greater
uncertainty with temperatures closer to the East Coast given the
proximity of an upper-trough over the Atlantic just to the east.

The latest WPC forecast was composed of a composite blend of the
00Z ECMWF/ECMWF AIFS/CMC and 06Z GFS guidance for the early to
middle part of the period. A contribution from the 00Z ECens and
then GEFS means was introduced with a reduction in the
deterministic guidance for the latter part of the period as the
guidance begins to diverge with the evolution/progression of the
upper-flow over the western to central U.S. overall, as well as
with the track and evolution of the noted strong surface system.

...Weather/Hazards Highlights...

At the surface, wavy frontal boundaries lingering across the
Midwest will support scattered to widespread showers and
thunderstorms across much of the Middle Mississippi/Ohio Valleys on
Monday into Tuesday. An embedded upper-wave rounding a prominent
upper-ridge with a hot, humid airmass in place will support the
potential for robust thunderstorms capable of heavy downpours and
flash flooding. A Slight Risk of Excessive Rainfall has been
outlooked over portions of the Middle Mississippi to Lower Ohio
Valley for day 4/Monday to cover this threat. A Marginal Risk has
been included for day 5/Tuesday as the threat follows the upper-
wave a bit further east into Great Lakes, Upper Ohio/Tennessee
Valleys and southern Appalachians. Additional heavy rainfall will
remain possible in the Upper Ohio Valley Wednesday, with the
potential for more Slight Risks as confidence grows in the coverage
and evolution of convection each day. Daily, scattered
thunderstorm chances are also expected over the Southeast with the
hot, humid airmass in place. A frontal boundary settling over
South/southwest Florida may lead to a locally heavy rainfall
threat.

Meanwhile, a potentially significant low pressure system is
expected to spin-up over the northern Plains/Upper Midwest by mid-
week as a deep upper-trough approaches from the west. Plentiful
shear due to strong low-level and upper-level wind fields with the
approaching trough and deepening low as well as a warm, humid
airmass leading to more than sufficient instability will support a
threat for severe weather, with the Storm Prediction Center (SPC)
highlighting portions of the northern Plains Tuesday and Upper
Midwest Wednesday. Heavy rainfall/flash flooding also looks to be a
concern and a day 5/Tuesday Marginal Risk has been maintained.

The deep upper-troughing over the Pacific Northwest into the
northern Rockies and multiple frontal passages will bring cooler
conditions and chances for scattered showers and thunderstorms on
Monday into Tuesday. As the upper-trough shifts eastward mid-week,
very moist, persistent upslope flow setting up over Montana will
bring an increasing risk of heavy rainfall and flash flooding
concerns. Further south into the Great Basin/Four Corners region,
gusty winds given the strong upper-flow and multiple frontal
passages along with very low relative humidity has lead to a
Critical Risk of Fire Weather from the SPC Monday into Tuesday and
possibly continuing into Wednesday.

An amplifying upper-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. Meanwhile, the deep-upper trough over
the western U.S. will lead to some below average conditions over
the Pacific Northwest early next week to the northern Rockies/Great
Basin mid- to late next week.


Putnam


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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