571
FXUS01 KWBC 200821
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Thu Jun 20 2024

Valid 12Z Thu Jun 20 2024 - 12Z Sat Jun 22 2024

...Heavy rain/flooding threats and gusty winds over South Texas
gradually decrease today as Tropical Storm Alberto makes landfall
in Mexico and dissipates...

...Heavy rain and flash flooding concerns increase across the
northern Plains to the upper Midwest later Thursday into Friday as
scattered thunderstorms could result in localized flooding issues
from the southern High Plains to the Four Corners...

...A heat wave will persist over the Great Lakes, Ohio Valley, and
portions of the Northeast into the weekend as heat intensifies in
the western U.S....

Tropical Storm Alberto centered over the southwestern Gulf of
Mexico has begun heading west toward northern Mexico early this
morning.  Organized bands of heavy rain extending north from the
center have already brought close to 10 inches of rain locally
near the mid-Texas coast.  As the heavy rain bands continue to
steadily move west through the Rio Grande Valley into northern
Mexico today, the heavy rain and flooding threats will gradually
decrease across South Texas.  Strong and gusty winds will also
gradually weaken with time.  Some of the tropical moisture from
Alberto will be drawn northward and energize the scattered showers
and thunderstorms from the southern High Plains to the Four
Corners heading into the weekend.  These showers/storms will be
more numerous during the late afternoon to early evening hours in
these areas.

Meanwhile, the National Hurricane Center continues to monitor the
potential of tropical cyclone formation over the western Atlantic
as a tropical wave moves west-northwest in the general direction
of northeastern Florida and Georgia.  Some enhanced rainfall with
gusty winds can be expected to reach these areas Thursday night
and will likely linger through much of Friday.

Across the northern tier states, relatively less active weather is
expected today as a high pressure system brings cooler and more
stable air from Canada.  However, the next piece of energy exiting
the central Rockies will set up the next episode of heavy rain and
strong to severe storms across the northern Plains to the upper
Midwest beginning tonight.  A couple rounds of heavy rain focusing
just north of a nearly stationary front across the region will
result in slight to moderate risks of excessive rainfall from
eastern South Dakota, across southern Minnesota into western
Wisconsin through Saturday morning.  Farther east, scattered
thunderstorms are likely across the Great Lakes region and the
Northeast near and north of the stationary front.  Marginal to
slight risks of severe storms are delineated each day from the
Storm Prediction Center (mainly for the threat of severe wind but
with some low chances for hail), and marginal risks of excessive
rainfall are in place as well.

All these rain and thunderstorm areas are taking place along the
periphery of an upper ridge/heat dome that edges from the
Mid-Atlantic into the Mid-South over the next couple of days and
sustains a heat wave across the Great Lakes, Northeast, and
Mid-Atlantic. Afternoon high temperatures and warm overnight lows
will challenge daily records and even some monthly and all-time
records. Heat index readings are expected to peak from 100 to 105
degrees in many locations. Those without access to reliable air
conditioning are urged to find a way to cool down. Record warm
overnight temperatures will prevent natural cooling and allow the
heat danger to build over time indoors without air conditioning.
Temperatures may be lower and less hazardous closer to the coast
if/where sea breezes form. By Friday, conditions should improve
over New England as cooler air dips a bit farther south into the
area behind a front, but temperatures well into the 90s and higher
heat indices are forecast to continue across the Ohio Valley to
Mid-Atlantic. Meanwhile, cooler than average highs are likely into
the southern High Plains with the clouds and rain forecast, but
temperatures over the West will gradually rise above normal
Thursday and Friday.  In the western U.S., it appears that the
heat will increase by Saturday as triple-digit high temperatures
are forecast for the Central Valley of California and the Great
Basin.

Kong/Tate


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