Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
354 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...

...Heavy rain threat emerging along the central Gulf Coast Monday,
following by an increasing heavy rain threat toward the Texas Gulf Coast
later Tuesday and especially Wednesday...

...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
an approaching area of low pressure over the Gulf. 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 5-10+"
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.

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