616
FXUS02 KWBC 021908
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
308 PM EDT Tue Jul 2 2024

Valid 12Z Fri Jul 05 2024 - 12Z Tue Jul 09 2024

...A major heatwave expected to persist for the West Coast through
early next week with excessive heat likely for the interior lower
elevations of California and the Desert Southwest...

...Beryl could be in the vicinity of Texas Gulf coast early next
week...

...Overview...

The main thing making weather headlines during this forecast period
will be a prolonged heatwave encompassing much of the West Coast
with the most intense heat focusing along the Central Valley of
California and extending into the lower elevations of the Desert
Southwest. Hot and humid conditions will also continue for much of
the southern states and extending to the East Coast. A low pressure
system is forecast to cross the Upper Midwest and bring a round of
heavy rain and storms to the Great Lakes on Friday, with
additional storms near the trailing frontal boundary across
portions of the Southern Plains and extending east to the Ohio
Valley and the Mid-Atlantic region. Meanwhile, the National
Hurricane Center is forecasting tropical cyclone Beryl to reach
southern Texas by early next week.


...Guidance/Predictability Assessment...

Model guidance this morning continues to indicate good agreement
that mean troughing will persist over the mid-section of the
country through the medium-range period while a warm ridge will
persist and nudge farther inland into the western U.S. The model
consensus has been nudging the mean trough over the mid-section
country southward. This has resulted in a subtle southward shift of
the track of an occluded low across the Great Lakes, as well as a
southward dip of the trailing cold front over the southern Plains.
The southward dip of the mean trough has also lead to a slightly
more amplified upper-level pattern across the U.S., as the upper
ridge over the western U.S. and off the East Coast remain at
similar intensity. The southward dip of the mean trough also has
implication regarding how far north tropical cyclone Beryl will
eventually track toward the western Gulf Coast region. Subtle
mutual interaction between the mean trough and the circulation of
Beryl together with the uncertain distance between the two systems
would introduce a higher degree of forecast uncertainty over the
vicinity of southern Texas, western Gulf Coast, and northeastern
Mexico for early next week.


...Weather/Hazards Highlights...

Heavy rain with embedded thunderstorms are likely to continue
across northern Wisconsin and into the Upper Peninsula of Michigan
going into Friday as an occluded surface low tracks across the
region, and a Marginal Risk will remain there for the Day 4 period.
Farther south, a corridor of heavy showers and storms is likely
from northern Texas to the Tennessee River Valley ahead of a cold
front. The western extent of the Marginal Risk area over the
southern Plains for Friday has been trimmed off due to the
aforementioned southward dip of the front.

Looking ahead to Saturday, there is enough of a model signal to
maintain the Marginal Risk area for portions of the Mid-Atlantic,
where some strong thunderstorms with heavy rain rates could
develop quickly in the vicinity of the cold front with its forward
motion slowing down. Some of the outer rain bands of Beryl could
be approaching southern Texas by late Saturday and into early
Sunday, but the intensity and location of Beryl remain uncertain
at this point.

It will continue to remain hot and humid across Texas and extending
eastward across the Deep South and into the Southeast for the end
of the week and into next weekend, with highs in the middle to
upper 90s and dewpoints well into the 70s. It will also be getting
very hot for the inland lower elevations of California with
widespread 105-115 degree readings likely. Readings could reach 120
degrees at the hottest locations in the Desert Southwest. Daily
temperatures records may be tied or broken in many cases. The heat
will likely expand across inland portions of Washington, Oregon,
and much of the Intermountain West by the Sunday-Tuesday time
period, with 100+ degree highs likely for the lower valley
locations.

Kong/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 (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














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