648
FXUS02 KWNH 130658
PREEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
257 AM EDT Sun Jul 13 2025

Valid 12Z Wed Jul 16 2025 - 12Z Sun Jul 20 2025

...Florida to the central Gulf Coast could see heavy rain next
week...


...Overview...

A typical summertime pattern will be in place much of the medium
range period next week with an expansive upper ridge stretched
across the Southern U.S. and progressive shallow troughs moving
through the northern stream flow. A shortwave over the northern
Rockies at the start of the period Wednesday will drift eastward
with time, sending a cold front through the northern and central
U.S.. This will aid convection over much of the country east of the
Rockies. Farther south, weak low pressure near/over Florida
drifting west into the Gulf will keep heavy rain threats over the
Sunshine State and toward the central Gulf Coast through the latter
part of next week. Meanwhile monsoonal moisture increases through
the period in the Four Corners states to south-central High Plains.
Upper ridging from the southern Plains to the East will increase
heat into next weekend.


...Guidance/Predictability Assessment...

Model guidance continues to struggle with the details and timing
of shortwaves through the northern stream flow within the low
amplitude pattern. The first shortwave through the Upper
Midwest/Great Lakes shows improved timing compared to previous
runs, and a general model compromise works well for the first few
days of the period. Energy rounding a ridge over the northeast
Pacific may reach the Pacific Northwest states late week, but with
some question on strength/timing. The GFS is weaker and slower, a
result of more amplified ridging over west- central Canada. This
also allows for more amplification of another downstream shortwave
into the Great Lakes. The ECMWF is more progressive with the
initial shortwave and much flatter flow by the time it reaches the
Great Lakes. ECMWF also has a stronger upper high over the
Southeast. The ensemble means seem like a good middle ground
solution for the second half of the period and the WPC forecast
trended much heavier towards the means Friday into next weekend.


...Weather/Hazards Highlights...

A surface low pressure system (which the National Hurricane Center
is now monitoring with low probabilities of tropical cyclone
development) will be retrograding across Florida into the Gulf by
mid-week. Moisture above the 90th percentile is likely to be in
place and promote multiple inches of rain in the Florida Peninsula
from Monday-Tuesday (short range period) into Wednesday. By The low
should be moving west into the Gulf by Thursday, but enhanced
moisture will remain in place across Florida, and spread into the
central Gulf Coast. A Marginal Risk is included on both the Day
4/Wednesday and Day 5/Thursday Excessive Rainfall Outlook/ERO for
those areas. Heavy rain may linger in the Gulf Coast region into
next weekend.

Much of the nation from the Rockies eastward will be active with
typical summertime convection in a warm and unstable airmass. A
cold front moving through the northern/central Plains and eastward
will support showers and thunderstorms with ample moisture and
instability, resulting in a heavy to excessive rainfall threat. The
ERO on Wednesday shows a broad Marginal Risk area from the Upper
Midwest/Middle Mississippi Valley eastward into the Ohio Valley and
Central Appalachians. On Thursday, the marginal risk ERO shifts
more into the Ohio Valley/Mid-Atlantic and Northeast. Model
guidance varies considerably with placement of heavy rain amounts
on both days, so the Marginal is quite broad in order to cover the
widespread but low- end threat. Some areas may eventually need
embedded Slight Risks in future cycles if models converge on
placement and amounts of heavy rain.

Elsewhere, monsoonal moisture will gradually increase in coverage
across the Southwest/Four Corners/southern Rockies region. Marginal
risks are in place across southern Arizona, New Mexico, and points
north. More widespread monsoonal moisture will continue making its
way northward in this region through next weekend.

Hot weather may linger in the Pacific Northwest through around
midweek, but temperatures in the northern High Plains will cool
dramatically by Wednesday with highs around 15 to 25 degrees below
normal. Temperatures look to be a few degrees cooler than average
for the south-central U.S. for much of next week as clouds and rain
hold temperatures down. The Great Lakes and Northeast will see an
increase in heat next week with a building ridge over the region,
with somewhat widespread Major (level 3/4) HeatRisk showing up in
those areas mid-late week. Meanwhile the Southeast should be near
normal to a few degrees above, for typical summer heat and
humidity.


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




$$