Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
314 PM EDT Mon May 20 2024

Valid 00Z Tue May 21 2024 - 00Z Thu May 23 2024

...Continued severe weather and excessive rainfall threats over parts of
the central U.S. into mid-week...

...Cool conditions with periods of shower and high elevation snow chances
from the Rockies to the Pacific Northwest...

...Well above average and summer-like temperatures to start the week from
the central/southern Plains to the Northeast...

An energetic upper-level pattern featuring multiple shortwaves emitting
from a broader long-wave trough over the western U.S. will continue a
period of active weather throughout the central U.S. this week. Showers
and thunderstorms are already pushing eastward across the Great Lakes this
afternoon ahead of a leading system over the Upper Midwest. By tonight, a
developing surface cyclone over the central High Plains in response to a
deeper shortwave ejecting into the Plains will spark numerous
thunderstorms from northeast Colorado through Nebraska and Iowa. These
storms may contain damaging wind gusts, large hail, and a few tornadoes,
which has prompted an Enhanced Risk (level 3/5) for severe thunderstorms
from northeast Colorado to central Nebraska. Heavy rain may also lead to
scattered instances of flash flooding tonight for parts of Iowa. This low
pressure system is expected to remain compact and strengthen as it
progresses into the Upper Midwest on Tuesday. Once again the threat of
severe weather and heavy rain will be associated with this system
throughout the Midwest and Great Lakes. Thunderstorms are expected along
and ahead of a cold front as it extends southward into the southern
Plains, with widespread moderate to heavy rain north of a warm front
including parts of Minnesota, Wisconsin, and northern Iowa. The Storm
Prediction Center has issued a Moderate Risk (level 4/5) for severe
thunderstorms from south-central Iowa to northwest Illinois in order to
capture the threat of damaging wind gusts and the potential for a few
strong tornadoes. As the aforementioned low shifts into southwestern
Ontario Wednesday morning (potentially at record strength for the month of
May) and the attached cold front slides into the Mid-South and southern
Plains, heavy rainfall remains a concern where this frontal boundary comes
to a crawl. A Slight Risk (level 2/4) of Excessive Rainfall is in effect
between northeast Texas and eastern Oklahoma to the lower Ohio Valley as
thunderstorms could be slow-moving and contain intense rainfall rates.

Cool and unsettled weather underneath the broad upper trough is
anticipated to remain locked-in over the Northwest and Rockies through at
least midweek. Snow is possible into the higher elevations of Wyoming and
Colorado on Tuesday before winter weather chances enter the northern
Rockies on Wednesday, with snow levels possibly dropping to around 7000
feet. High temperatures in these regions are also expected to remain on
the cooler side and 10 to 25 degrees below average.

Meanwhile, for areas south and east of the main storm system impacting the
central U.S. this week, highs are expected to soar above average and into
potentially record-breaking territory for certain spots. Widespread highs
into the 80s and low 90s are forecast from the Midwest and Deep South to
the Northeast through Wednesday, with mid-to-upper 90s and triple digits
in parts of South Texas and the southern High Plains. This heat could be
particularly dangerous for people dealing with a loss of power in parts of
Texas. Warm overnight temperatures will offer little relief and high
humidity could also lead to heat index readings over 110 degrees.

Snell

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