726
FXUS01 KWBC 270725
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
324 AM EDT Thu Jun 27 2024

Valid 12Z Thu Jun 27 2024 - 12Z Sat Jun 29 2024

...Flash flooding and severe weather threat across portions of the
northern/central Plains Thursday expands into the Midwest Friday...

...Dangerously hot conditions continue over portions of the
southern Plains...

...Monsoon-like conditions persist for the Four Corners Region...

An upper-level trough passing over the Pacific Northwest and the
Rockies will begin to overspread the northern/central High Plains
Thursday afternoon. Lee cyclogenesis will lead to a deepening
surface low over the northern High Plains, with strengthening wind
fields helping to reinforce a warm front lifting northeastward
across the High Plains and a trailing cold front extending
southwest into the Rockies. Scattered thunderstorm development is
expected Thursday afternoon in the presence of moist, upslope
flow. Ample instability and strengthening wind fields will promote
some more intense storms, with the Storm Prediction Center issuing
an Enhanced Risk of severe weather (level 3/5) for the threat of
very large hail and a few tornadoes. Storms will likely increase
in coverage into the evening given enhanced forcing along the
cold/occluded front, with a line of storms expected to propagate
eastward with a threat for significant damaging winds. Some
locally heavy downpours will also be possible given anomalously
high moisture available. A Slight Risk of Excessive Rainfall
(level 2/4) extends east through North Dakota as more widespread
storms and heavy rainfall are expected with the eastward moving
convective system, and some scattered flash flooding is possible.
A similar scenario exists further south as more widespread, heavy
downpour producing storms are expected to organize and grow
upscale along and ahead of the northeastward moving warm front.
Another Slight Risk of Excessive Rainfall is in place for northern
Kansas and southern Nebraska to cover the threat for some
scattered flash flooding here as well.

The upper-level trough/surface frontal system will continue
eastward on Friday, bringing storm chances to the Upper/Middle
Mississippi Valley and Great Lakes region back southwest along the
cold front through the central Plains. Initial storm focus will be
ahead of the northeastward lifting warm front over the Middle
Mississippi Valley, with the chance storms to the west overnight
Thursday persist across the region. Then, later in the afternoon,
a renewed round of storms is expected along the increasingly
east-to-west oriented cold front. Storm motions relatively
parallel to the boundary will bring a higher threat for heavier
rain totals as storms repeat over the same regions, with a Slight
Risk of Excessive Rainfall extending from the Upper/Middle
Mississippi Valley west through the Middle Missouri Valley. More
sensitive conditions over the area due to recent heavy rainfall
will increase the risk for flash flooding. In addition, there is
another Slight Risk of severe weather (level 2/5) over the same
region and west to the central High Plains with large hail,
damaging winds, and a few tornadoes all anticipated.

To the south, temperatures will remain dangerously hot over the
southern Plains under the influence of an upper-level high over
the Southwest/south-central U.S. Forecast highs Thursday will
range from the upper-90s to low-100s from central/northern Texas
west through the southern High Plains. Higher humidity over
portions of central/northern Texas into southern Oklahoma have
prompted Heat Advisories as Heat Index values may reach as high as
110. Hotter temperatures will flow back northward following the
warm front on Friday, with highs in the upper 90s to low 100s
reaching up into portions of the central Plains. Very warm lows in
the upper 70s to lower 80s will provide little relief overnight.
An upper-level shortwave dipping down into the Southeast and
interacting with a quasi-stationary frontal boundary will bring
shower and storm chances as well as some relief from the intense
heat to most of the Lower Mississippi Valley and Southeast.
Forecast highs will remain in the upper 80s to low 90s over the
next couple of days. However, areas of coastal Georgia north
through the Carolinas to the southeast of the boundary will stay
hot, with highs in the mid-90s and heat indices potentially
reaching into the low 100s. Unfortunately, upper-level ridging
expanding over the southern tier of the country will begin to
bring more widespread heat back to the region this weekend.

Monsoon-like conditions will persist over the Four Corners region
Thursday with the upper-level high overhead continuing to steer
tropical moisture northward. The upper-level trough arriving from
the west will help to encourage scattered thunderstorms with the
threat for locally heavy downpours. A Slight Risk of Excessive
Rainfall covers portions of western New Mexico north through
western Colorado and far eastern Utah for the risk of some flash
flooding. The trough will help to break down the upper-high as it
moves eastward on Friday, helping to reduce the influx of moisture
and keep the highest storm chances and risk for some isolated
flash flooding limited to southeastern Arizona.

Putnam


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
$$