432
FXUS02 KWBC 151900
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Sun Jun 15 2025

Valid 12Z Wed Jun 18 2025 - 12Z Sun Jun 22 2025


...Intensifying heat threat from the Plains/Midwest to the
South/Southeast into later this week and next weekend...

...Severe weather and heavy rainfall/flash flooding threats from
the Midwest/Great Lakes to the Mid-Atlantic into mid-later week...


...General Overview...

Severe weather and heavy rainfall/flash flood threats will work
across the Midwest/Great Lakes through midweek as fueled by wavy
frontal enhanced pooled moisture and instability. These threats
will persist Thursday as storms focus from the Northeast down
through the Appalachians/Mid- Atlantic. An expanding/intensifying
heat threat for the start of Summer will unfold across portions of
the Plains/Midwest to the South//Southeast into late week/next
weekend as a strong upper-ridge begins to build in. There is also
some signal for an increase in tropical moisture and rainfall into
South Texas and the western Gulf Coast into next weekend.

...Guidance/Predictability Assessment...

Models and ensembles overall continue to indicate that a highly
unsettled and active zonal flow pattern will continue into to mid
next week with multiple short-wave trough energies traversing the
central/eastern U.S. keeping unsettled weather in the forecast, but
with less specificity in local details. Upstream, a deep upper-low
anchored over the northeastern Pacific looks to be the source for
these upper- waves including one that will traverse the CONUS mid
week helping to briefly dent upper-ridging over the southwestern to
south-central U.S. Then, into later next week, guidance also
continues to agree there will be a shift to a much more amplified
pattern following the progression of the noted upper-wave to the
East Coast, with upper-ridging returning and expanding northward
over the southwestern to central U.S. and eventually eastern U.S.
Meanwhile, guidance shows the upper-low over the northeastern
Pacific will begin to shift southward and overspread portions of
the northwestern U.S. and the West Coast, eventually leading to an
amplified upper-trough dug into the West next weekend. A northward
shift of the storm track should begin to trend down precipitation
chances over much of the central/eastern U.S. for this timeframe.

Guidance overall remains in reasonably good agreement with most of
the synoptic scale features and a transitional trend for
amplification in a pattern with above average predictability.
However, guidance continues to suffer from widespread smaller scale
system and convective focus variances. Accordingly, the WPC medium
range product suite was mainly derived from a broad blend of best
clustered guidance from GFS/ECMWF/CMC model and emsemble mean guidance
along with the compatible National Blend of Models and WPC
continuity through medium range time scales.

...Weather/Hazards Highlights...

It still remains the case that highly unsettled weather will remain
in the forecast from portions of the east-central to eastern U.S.
into mid-later week as an upper-wave/associated surface frontal
system pushes eastward with deepened moisture in place. On
Wednesday (Day 4), widespread convection is expected along and
ahead of surface low pressure and a trailing cold front through the
Great Lakes/Midwest southwest through at least the Mississippi
Valley and possibly into the southern Plains. The storms,
potentially organized, will be capable of producing locally heavy
rainfall with guidance QPF signals of 1-3"+. A Marginal Risk ERO
remains across the region and it is likely a more focused corridor
of higher risk will be needed once there is more certainty in the
areal placement. In addition to heavy rainfall/flash flooding, the
Storm Prediction Center has also highlighted a severe weather risk
as moderate instability and sufficient shear will bring the threat
for large hail and damaging winds, particularly with any organized
convective lines. The focus for storms will shift eastward with
the system on Thursday (day 5) with another Marginal Risk ERO
stretching along/near the cold front from northern New England and
the Interior Northeast southwest through the Appalachians into
portions of the Tennessee Valley. Additional scattered storms will
be possible ahead of the cold front across the Mid-Atlantic and
through portions of the Southeast/Lower Mississippi Valley
Wednesday-Thursday. Storm/rainfall focus Friday-Sunday should
shift southward with the cold front to the Gulf Coast/Florida, as
well as along the northern tier from the Upper Midwest/Great Lakes
to the Interior Northeast as the storm track lifts northward. A
signal also remains for a multi-day enhanced tropical moisture feed
from the Gulf to northeast Mexico and South Texas/West Gulf Coast
with the potential for locally heavy rainfall. A Day 5/Thursday ERO
Marginal Risk area has been introduced to address this potential.
Upstream, the energetic approach of a deep upper-trough/Pacific
system and northern stream energies into the West look to bring
colling temps and increasing precipitation chances to the Pacific
Northwest by Friday and across with northern Rockies/High Plains
next weekend in unsettled flow with moderate rainfall potential.

Expect a focus for above average temperatures across the
Intermountain West/Southwest early to mid-next week to shift into
the central Plains and the Middle/Upper Mississippi Valley by late
next week as a strong upper-ridge begins to build in bringing
heat/muggy conditions to start the Summer. The heat will also begin
to intensify across the Lower Mississippi Valley and Southeast as
well as the upper-ridge intensifies eastward. Forecast heat indices
late next week/weekend range from 95-100 across the central Plains
to Middle/Upper Mississippi Valley, 95-100 across the Southeast,
and 105-110+ for the Lower Mississippi Valley and Gulf
Coast/Florida. Hotter temperatures/muggy conditions are also
expected from the Ohio Valley east into the Mid-Atlanitc during the
middle of next week before a cold front passage brings relatively
more comfortable conditions late next week/weekend. Highs will
begin to trend cooler and below average by as much as 10-15 degrees
across portions of the Northwest by Friday and expand into the
Great Basin/northern Rockies by the weekend as an upper-trough and
associated surface cold front from the northeast Pacific begin to
overspread the region.

Schichtel/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 (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
































$$