597
FXUS01 KWBC 180846
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
445 AM EDT Tue Jun 18 2024

Valid 12Z Tue Jun 18 2024 - 12Z Thu Jun 20 2024

...Significant heavy rain/flash flooding threat with gusty winds
well ahead of Potential T.C. One expected to impact southern Texas
on Wednesday...

...More rounds of heavy rain and severe thunderstorms expected for
the northern Plains and upper Midwest today before shifting south
into the central Plains on Wednesday...

...A heat wave will persist over the Great Lakes, Ohio Valley and
the Northeast through midweek...

...Late-season wet snow continues across the high-elevations of
the northern Rockies today before tapering off early on
Wednesday...

An active weather pattern continues across the U.S. mainland.
This weather pattern that features snow, heat, heavy rain, severe
thunderstorms, strong winds, and fire weather is now bringing
Potential Tropical Cyclone One in the midst.  A low pressure
system currently intensifying along a frontal boundary is
fostering another round of heavy rain and severe thunderstorms
across the northern Plains into the upper Midwest early this
morning.  The potent upper trough and the associated dome of cold
air have continued to result in a round of late-season wet snow
across the higher-elevations of the northern Rockies together with
rather strong wind gusts.  With less potent jet stream energy
behind this system, the low pressure system will quickly eject
into southern Canada by this evening, bringing the inclement
weather across the northern Plains to an end by Wednesday morning.
 However, a sharp front trailing south and southwest from the low
center will likely trigger an axis of heavy rain and severe
thunderstorms from the central Plains to the upper Midwest by
tonight into Wednesday morning.  From Wednesday into Thursday
morning, the rain/storms should gradually become more scattered in
nature across the central Plains as a cool high pressure system
passes to the north.  This high pressure system will also push the
widely scattered showers and embedded thunderstorms farther east
into the lower Great Lakes and interior New England through
Thursday morning.

In stark contrast to the cool, windy, rainy and even snowy weather
in the West, a heat wave will settle and persist across the Great
Lakes, Ohio Valley and the Northeast through the next few days.
Forecast highs today and Wednesday will reach into the mid- to
upper 90s, even the century mark Wednesday and Thursday afternoon
at the hottest locations in interior 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 heat.

Another big weather story over the next couple of days will be in
the Gulf of Mexico where the National Hurricane Center has already
initiated advisories on Potential Tropical Cyclone One.  An
elongated upper trough digging into the southern Plains and
northeastern Mexico has already drawn a plume of tropical moisture
northward into the central Gulf Coast region.  This upper trough
will be instrumental in drawing the tropical moisture well north
of the center of PTC One into southern Texas mainly on Wednesday
as PTC One tracks west toward northern Mexico.  An axis of very
heavy rain may develop just inland of the Texas coastline behind a
coastal front with dynamic support from the elongated upper
trough.  This pattern could result in locally heavy rainfall in
excess of 10 inches near or just inland of the lower to middle
Texas coast which would result in significant flash flooding.  The
heavy rain is forecast to push farther inland across the Rio
Grande Valley early on Thursday.  In addition to the heavy
rainfall, some coastal flooding along with tropical-storm-force
winds can be expected up the Texas coast on Wednesday.  See the
latest advisory from the National Hurricane Center for additional
detailed updates.  Meanwhile, fire danger across the Four Corners
region should gradually ease over the next few days with the
arrival of slightly cooler air followed by the arrival of moisture
from the northern edge of Potential Tropical Cyclone One.

Kong/Putnam


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

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