…Record heat relents over the Southern Plains as the heat shifts
northward into the central/northern Plains and Midwest…
…Severe storms and isolated flash flooding possible for the Northern
Plains/Upper Midwest Sunday-Monday…
…Daily Monsoonal thunderstorms continue across the Four Corners region,
shifting eastward into the southern Rockies/High Plains…
A relentless heatwave over portions of the Southern Plains will finally
start to ease a bit Sunday following another day of possibly
record-tying/breaking high temperatures into the mid-100s today
(Saturday). Forecast highs in the mid-90s Sunday and Monday will still be
hot but closer to average. Unfortunately, the upper-level ridge
responsible for the hot weather will shift eastward and build northward,
bringing dangerous heat into the central/northern Plains and Midwest the
next couple of days. Highs will soar into the mid- to upper 90s, with some
low 100s possible. When combined with high humidity values, heat indices
will reach into the 105-110 degree range, with widespread heat-related
advisories and warnings in effect, particularly for portions of the
Middle/Upper Missouri and Upper Mississippi Valleys. Extra caution should
be observed by those without effective air conditioning and anyone who
must be outdoors should remain adequately hydrated. A cold front will
bring relief to portions of the Northern Plains Monday.
This cold front pushing through the Northern Plains/Upper Midwest will
bring increasing storm chances Sunday and Monday. Plentiful moisture,
strong instability, and increasing upper-level winds as a shortwave
traverses the broader ridge aloft will lead to the threat of some severe
thunderstorms, with the Storm Prediction Center highlighting the Red River
Valley of the north on Sunday with a Slight Risk (level 2/5) of severe
weather. Isolated large hail and damaging winds will be the main threats.
Then, on Monday, another Slight Risk is in effect ahead of the front over
portions of the Upper Mississippi and Missouri Valleys, with a chance for
isolated but potentially larger hail and significant damaging winds. Some
locally heavy rainfall and isolated flash flooding will also be possible.
Some organized clusters of storms will also be possible for the Middle
Mississippi Valley through Sunday morning ahead of separate frontal system
lifting northeastward across the Plains, bringing locally heavy rainfall
and isolated flash flooding.
To the southwest, daily Monsoonal thunderstorm chances will continue,
focusing over the Four Corners region through this evening before shifting
eastward into the central and southern Rockies/High Plains Sunday/Monday.
Deep moisture and moderate instability will lead to some more intense
thunderstorms with locally heavy downpours, and some isolated flash
flooding will be possible, especially for terrain sensitive areas such as
burn scars. Besides the rainfall, the big story across the West the next
few days will be the much below average temperatures expected behind a
strong cold front pushing through the region. Widespread high temperatures
in the 60s and 70s will be common today and tomorrow across the Pacific
Northwest, northern Rockies, Great Basin, and northern California, near
record low maximum values for some locations. Morning lows Sunday will dip
into the 40s and even 30s for much of the interior Pacific Northwest and
Great Basin, with a Frost Advisory in effect in northern Nevada. The focus
for these mild temperatures will shift eastward over the northern
Rockies/eastern Great Basin by Monday while conditions moderate to the
west, with highs back into the 80s. Some post-frontal showers and storms
will be possible over portions of the Great Basin this evening, becoming
more widespread across the northern Rockies/High Plains Sunday into
Monday. Elsewhere, some showers and storms with moderate to locally heavy
rainfall will be possible Monday into Tuesday over New England as an
upper-level wave passes over the region. Daily showers and thunderstorms
will also be possible for Florida and along the Gulf Coast with a
lingering frontal boundary in the region.
Putnam
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
