111
FXUS02 KWBC 011952
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
352 PM EDT Mon Jun 1 2026

Valid 12Z Thu Jun 4 2026 - 12Z Mon Jun 8 2026

19Z Update: The 12Z guidance has continued coming into better
agreement with the upper low dropping southeast towards the Pacific
Northwest through Saturday, but diverge some going into late Sunday
and Monday with the GFS holding onto the trough across the region
longer. There was still good overall support for lowering
temperatures from the NBM by a few degrees across portions of the
Intermountain West to account for this. There is also a persistent
signal for multiple thunderstorm complexes to develop across the
southern Plains for the end of this week and into Saturday as a
weak southern stream shortwave/low lifts northeast towards Texas,
and another area of enhanced rainfall across the Dakotas and into
the Upper Midwest on Thursday night into Friday. A broad Marginal
Risk is being maintained for now on both Days 4 and 5, but there
is definitely the potential for embedded Slight Risk areas in
future outlooks given a very moist airmass in place. The ensemble
means were gradually increased to about 40% by next Monday. The
previous forecast discussion is appended below for reference.
/Hamrick
-----------------------


...Overview...

The medium range, beginning this Thursday, will be active for the
Central U.S. and northern tier of the country, where weak mid-
level vortices will generate warm temperatures, scattered
thunderstorm activity and potential flash flooding for the Eastern
half of the country. A broad ridge over the East will flatten
beneath some of the aforementioned vortices moving through the
Great Lakes and Northeast this weekend. A deep upper- level trough
will bring renewed precipitation chances to the Northwest this
weekend.


...Guidance/Predictability Assessment...

Models are in relatively good agreement on the mid-level
disturbances over the Central U.S. and ridging in the Southeast.
There are uncertainties around the amplitude and timing of small
scale vortices propagating through the Southern Plains as well as
the speed of a surface cold front moving through the Northeast late
this weekend. There`s also some spread as to how the West Coast
trough evolves this weekend, with the Euro and Canadian
models developing a split flow pattern by next Sunday and Monday.

A general model blend is used on day 3 followed by an early
introduction of the GEFS on day 4 to due to the Euro`s slow moving
trough in the Western Atlantic. The Euro and Canadian ensemble
means are introduced to the blend on days 5 and 6 and are gradually
increased in weighting especially due to the emerging spread with
the trough in the West and ridge over the Central U.S..


...Weather/Hazards Highlights...

A quasi-stationary front draped across the northern tier of the
country may act a focus for scattered showers and thunderstorms
beginning on Thursday. Marginal risks (at least 5% chance) of
excessive rainfall are in effect across much of the Great Plains
and Middle/Upper Mississippi Valley, due, in part, to the forcing
caused by mid-level vortices propagating along a north-south axis
through the Central/Southern Plains.

Elsewhere, a deep trough will bring rainfall back to the Northwest
beginning on Friday and continuing through the weekend. Showers and
thunderstorms may develop along a cold front extending from the
Mississippi Valley to the Northeast on Sunday.

Temperatures will be average to above average over much of the
Eastern U.S. during the medium range period due to troughing over
the Plains and ridging over the Midwest. Temps in the upper 80s to
90s with overnight lows struggling to drop below 70 degrees could
lead to increased heat risk concerns along the Mid-Atlantic Coast this
weekend.


Kebede/Hamrick


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














$$