…Monsoonal thunderstorms could produce excessive rainfall for much of
the Four Corners region this weekend…
…Record heat begins to relent over the Southern Plains this weekend but
near record cool in the eastern U.S. and California…
…Critical Fire Risk and Red Flag Warnings in effect across much of the
Great Basin…
An anomalously amplified weather pattern across North America will
continue to bring sharply contrasting weather conditions across the U.S.
as we head into the weekend. This weather pattern will feature a warm
upper high over the southern Plains sandwiched in between two deep and
cold upper lows/troughs on either side of the East and West Coasts. A
deep and unstable southwesterly flow between the ridge and the upper low
near the Pacific Northwest will support monsoonal showers and
thunderstorms across the Four Corners region through the next few days.
Slot canyons and burn scars are particularly vulnerable to flash flooding.
The flash flooding threat dwindles a bit heading into the weekend as the
upper-ridge shifts slightly eastward and the main energy associated with
the upper low will be directed farther north toward the northern High
Plains where a new low pressure system is forecast to form by Saturday
night. Meanwhile, critical fire weather danger is forecast for the Great
Basin under gusty and dry conditions behind a cold front.
The large upper low dipping into the Pacific Northwest will continue to
provide very cool and damp conditions into the West Coast. In fact,
record cool high temperatures can be found across California on Saturday.
The
anomalous cool conditions will penetrate farther inland during the
weekend, overspreading much of the western U.S. by Sunday morning. In
contrast, another day of record high temperatures are forecast for
portions of Texas into Oklahoma on Saturday under the warm upper high
where 110s are possible in portions of Texas Panhandle into nearby
Oklahoma. This heatwave is showing signs of relenting by this weekend as
the cool air from the western U.S. upper trough begins to erode the upper
ridge. However, heat indices are forecast to reach into the upper 90s to
the mid 100s during the weekend while the heat begins to spread northward
into the Central Plains.
Meanwhile, very cool and pleasant weather for August will continue to
prevail across much of the eastern U.S. under the cool upper trough
together with a cool high pressure system at the surface. A gradual
warming trend is expected through the weekend for the eastern half of the
country as the high pressure system begins to slide off the East Coast.
Kebede/Kong
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
