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631 
FXUS02 KWBC 080626
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
226 AM EDT Sun Jun 8 2025

Valid 12Z Wed Jun 11 2025 - 12Z Sun Jun 15 2025


...Heavy rain and flash flood threat for the south-central U.S. 
next week...


...Overview...

A frontal boundary settled across the South early to mid week 
before eventually lifting northward will continue to provide focus 
for moderate to heavy rainfall across portions of the South and 
into the middle Mississippi Valley. To the north, a shortwave 
moving through the Northwest through the northern Plains will bring
showers and thunderstorms mid to late next week. Rainfall will 
increase in coverage across the Ohio Valley into the East next 
weekend ahead of shortwave energy lifting into the region from the 
southern Plains. 


...Guidance/Predictability Assessment...

The latest suite of model and ensemble guidance all continue to 
show above average agreement on the overall large scale pattern and
evolution during the medium range period, but still with plenty of
uncertainty in the details which would impact sensible weather. 
Early period issues surround waves of energy sliding through the 
Northeast, but a general model blend seems to provide a good 
starting point for details that will need until the short range to 
resolve. Behind this, there are differences in the timing and 
strength of a shortwave lifting from the Southern Plains into the 
Ohio Valley later in the week, which has bigger implications on QPF
coverage and amounts across this region. A shortwave into the 
Northwest mid week looks good for timing, but bigger issues arise 
next weekend with energy around an upper low as it drops southward.
This affects additional shortwave timing into the West. The late 
period blend for WPC leaned slightly more heavily on the ensemble 
means to help mitigate these differences.


...Weather/Hazards Highlights...

A trailing frontal boundary draped generally west to east across 
the South will continue to provide focus for numerous showers and 
thunderstorms through most of next week. Guidance continues to 
converge of central Texas into Oklahoma for multiple days of heavy 
rainfall, with parts of this area already primed from recent 
rainfall. Accordingly, the Days 4 and 5 Excessive Rainfall Outlooks
(valid Wednesday and Thursday) show slight risk areas across this 
region. Intentionally kept the slight risks (and surrounding 
marginal risks) broad given some lingering uncertainties in exactly
where possible convective complexes track and the location of 
heaviest rain. If the forecast materializes though, it is possible 
a moderate risk area may be needed at some point in the future. By 
Thursday and Friday, this front should lift north pulling the 
heavier rains out of Texas, but continuing for parts of Oklahoma 
into the middle Mississippi Valley, eventually moving into the Ohio
Valley and East next weekend.

A shortwave interacting with a frontal boundary across the 
northern tier will bring showers and storms across parts of the 
northern Rockies into the Upper Midwest. Moisture anomalies should 
be above the 90th percentile in especially Montana, supporting a 
Marginal Risk on the Wednesday and Thursday ERO. Additionally, 
convection is likely to move through the north- central U.S. along 
the cusp of the instability gradient and thus the Marginal Risk 
also extends east into the Upper Midwest.

A heat wave during the short range period over the West should 
moderate by the start of the medium range period, though above 
normal temperatures may continue across the West through the 
period. Daytime highs generally could be 5 to locally 15 degrees 
above normal. Otherwise, the rest of the country looks near normal 
or within a few degrees of normal depending on quick systems moving
through.


Santorelli


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 (QPF), excessive rainfall 
outlook (ERO), winter weather outlook (WWO) probabilities, heat 
indices, and Key Messages can be accessed from:

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




$$