122
FXUS02 KWBC 041832
PMDEPD

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
232 PM EDT Thu Jul 4 2024

Valid 12Z Sun Jul 07 2024 - 12Z Thu Jul 11 2024

***Dangerous and major heatwave continues for the lower elevations
 of California and the Desert Southwest into next week, and Beryl
 approaches southern Texas Sunday into Monday***

...Overview...

The dangerous and major heatwave will continue to affect much of
California and extending into the lower elevations of the Desert
Southwest and Intermountain West through the middle of next week.
Meanwhile, attention turns to the track of Hurricane Beryl as it
crosses through the Yucatan Peninsula and heads toward South Texas
late Sunday into Monday. Meanwhile, a quasi-stationary front
across the eastern U.S. will serve as a focusing mechanism for
showers and storms south of the boundary across the Deep South and
Southeast/Mid-Atlantic region, and this will be ahead of an upper
level trough that is expected to build across the Northern Plains
and Upper Midwest. Hot and humid conditions will also continue for
much of the southern states and extending to the East Coast.

...Guidance/Predictability Assessment...

For the synoptic pattern, there was relatively good agreement
across the latest deterministic and ensemble guidance. The 500 mb
heights are expected to feature a rather persistent and building
upper ridge over the Desert Southwest through at least the middle
of next week. By Day 7, there was enough model agreement to show a
passing shortwave and frontal boundary into the far Pacific
Northwest.

Meanwhile, downstream into the Central U.S. there is good
predictability for troughing over the Central Plains, Upper
Midwest, and Great Lakes with a passing shortwave trough helping to
reinforce the trough early to mid week next week. Finally, ridging
will remain in place across the Southeast U.S., extending along the
coastal areas into the Mid Atlantic.

Finally, the latest NHC track for Beryl brings the storm center
near the Mexico/Texas border early Monday morning. The guidance
lies just to the north of model consensus as it makes landfall and
then from there, uncertainty builds with the possible interaction
with a digging frontal boundary into the Plains, helping to recurve
the system further into Texas or alternatively, the system stays
south along the Mexico/U.S. border before dissipating. For now, the
official NHC track takes the center along the border.

The WPC QPF favored a blend of the NBM to start, followed by
increases using the latest ensemble bias corrected QPF as well as
some inclusion of the ECMWF and GFS for Beryl, to help increase
rainfall amounts across portions of South Texas and points
westward.

Beryl`s track will continue to be closely monitored over the next
several days, and the NHC has additional information pertaining to
this.

...Weather/Hazards Highlights...

For Beryl, WPC is maintaining Slight Risks on the Day 4 and Day 5
Excessive Rainfall Outlooks for South Texas. A lot depends on the
track and speed of the system, but potential exists for several
inches over the course of 2 days for far South Texas and possible
future upgrades across far South Texas along the U.S. border.
Further north into central/east central Texas, there is less
confidence on how Beryl interacts with an approaching frontal
boundary but potential exists for organized convection capable of
producing heavy rainfall. Meanwhile, heavy rainfall and flash
flooding will be possible on Day 4 across portions of Oklahoma and
Kansas with a shortwave trough and frontal boundary drop through
the region. Scattered showers and storms are likely to persist
across much of the Gulf Coast, Deep South, and the East Coast
states going into the middle of next week with a moist and unstable
airmass remaining in place.

Major heat will continue to make weather headlines for the West
Coast states, with 100+ degree high temperatures extending to
northern Washington for the entire forecast period. Highs will
likely reach the 110s for the lower elevations of inland
California, southern Nevada, and southern Arizona, with some 120s
possible for the normally hotter locations. Some of this extreme
heat will likely expand eastward to include much of the
Intermountain West, including Utah and Idaho where some triple
digits readings are expected. Numerous daily records are likely to
be established during this prolonged and dangerous heat event, with
major to extreme heat stress conditions. Even Wyoming and Montana
get above average temperatures by next Wednesday/Thursday as the
upper ridge slowly moves inland across the Rockies. Numerous daily
record high temperatures are forecast across much of this region.
Elsewhere, seasonal levels of heat and humidity can be expected
most days for the southern and eastern parts of the country,
although there will likely be some days that reach heat advisory
criteria in some areas.

Hamrick/Taylor


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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