812
FXUS01 KWBC 172036
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
435 PM EDT Mon Jun 17 2024

Valid 00Z Tue Jun 18 2024 - 00Z Thu Jun 20 2024

...A heat wave begins to settle in over the Great Lakes, Ohio
Valley and the Northeast today, continuing through midweek...

...Significant heavy rain/flash flooding threat for the Texas Gulf
Coast later Tuesday and especially Wednesday associated with
Potential T.C. One...

...Heavy rain and severe thunderstorms possible Tuesday/Wednesday
from the Upper Midwest into the Central Plains...

...Late-season wet snow will persist across the high-elevations of
the northern Rockies for the next couple of days...

An active week is in store across the U.S. as a heat wave builds
over the Great Lakes/Ohio Valley/Northeast, multiple areas of
flash flooding and severe weather impact the central U.S., and
even some late season snow continues in the northern Rockies. A
strong upper-level high will continue to build in over the Great
Lakes/Northeast, bringing the first significant heat wave of the
season to the region. Forecast highs Tuesday and Wednesday will
reach into the mid- to upper 90s, even well into northern New
England. Widespread, numerous record-tying/breaking high
temperatures are possible. Additionally, morning lows will remain
in about the mid-70s, at record-tying/breaking levels, providing
little relief from the heat overnight. The early arrival of this
magnitude of heat, the duration, abundant sunshine, and lack of
relief overnight will increase the danger of this heatwave beyond
what the exact temperature values would suggest. This is
especially true for those without adequate air conditioning, which
becomes more of a concern for locations further north that are not
as accustomed to periods of persistent, intense heat.

Another big weather story over the next couple of days will be a
significant plume of tropical moisture flowing northward into the
south-central U.S. along the western side of the ridge and
accompanying heavy rain/flash flooding threats. First, repeated
rounds of scattered, intense downpours will continue through
Monday night along portions of the central Gulf Coast as
thunderstorms feed of the incoming tropical moisture. A Slight
Risk (level 2/4) of Excessive Rainfall is in effect for the threat
of scattered flash flooding. Then, more widespread thunderstorms
will begin to spread into portions of the central/western Gulf
Coast later Tuesday and central/south Texas by Wednesday
associated with the approach of Potential T.C. One. Moderate Risks
(level 3/4) of Excessive Rainfall are in effect for these regions
with forecast areal average rainfall of 3"+, and locally higher
totals of 5-15" expected, especially for areas closer to the
coast. Rain rates may be torrential at times, approaching 3"+ per
hour. This will bring the threat for potentially numerous
instances of flash flooding. A more conditional threat may expand
into portions of north Texas Wednesday, and while rainfall totals
are not expected to be as high, some flash flooding will also be
possible through the Rio Grande Valley. In addition to the heavy
rainfall, some coastal flooding and gusty winds can also be
expected. See the latest advisory from the National Hurricane
Center for additional detailed updates.

Further north, additional rounds of showers and thunderstorms are
expected as the influx of moisture continues to interact with a
wavy frontal boundary draped across portions of the
northern/central Plains and Upper Midwest. A broad area of showers
and thunderstorms will continue through Monday evening along and
ahead of the front as it slowly lifts northward. A Slight Risk of
Excessive Rainfall is in effect over portions of the northern
Plains/Upper Midwest where the available moisture, as well as
impressive upper-level dynamics associated with an approaching
trough, may lead to some heavier rain rates (2" per hour) and
scattered flash flooding, especially in urban areas. A Slight Risk
of severe weather (level 2/5) is also in effect from the Storm
Prediction Center, spreading further westward into the
northern/central High Plains, for some large hail, damaging winds,
and a few tornadoes. The front will begin to push back
southeastward as a cold front Tuesday ahead of the approaching
trough before stalling out through the Middle Mississippi/Missouri
Valleys ahead of the eastern ridge by Tuesday night. Slight Risks
of Excessive Rainfall are outlined from the Upper Midwest
southwest through the Middle Missouri Valley into the central
Plains Tuesday, and again for the Middle Missouri Valley
Wednesday. Additional rounds of storms along and ahead of the
front will have the tendency to repeat/back-build over the same
areas along the stalling front, increasing the potential for
locally heavy rain totals and some scattered flash flooding. There
is also a Slight Risk of severe weather Tuesday over the same
region as some storms may produce large hail/damaging winds.

To the west, the unseasonably strong upper-level system will also
continue to bring an intrusion of much cooler, below average air
into portions of the northern/central Plains/Rockies and Great
Basin. Forecast highs on Tuesday will be in the 50s and 60s in the
northern Rockies/High Plains, with some low 70s into the Great
Basin. In addition, forecast morning lows on Tuesday in the low to
mid-30s throughout much of the Great Basin have prompted
Frost/Freeze-related Warnings and Advisories. Temperatures should
recover a bit Wednesday for the Great Basin and northern Rockies
while portions of the central Plains drop into the 60s following
the cold front passage. Areal showers and thunderstorms with some
moderate rainfall will also linger over the northern Rockies/High
Plains Monday evening and into the day Tuesday before tapering off
by later Tuesday night. Winter-weather related Warnings and
Advisories remain in effect as moderate to heavy snow continues
for higher mountain elevations. While most of the accumulating
snow should remain above about 6000-7000 feet, some of the higher
valleys may see some flakes mix in.

Putnam


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

$$