Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
359 PM EDT Sat Sep 11 2021

Valid 00Z Sun Sep 12 2021 - 00Z Tue Sep 14 2021

...Developing tropical activity over the Bay of Campeche expected to
produce heavy rainfall and concerns for flash flooding by late Sunday and
through the early to middle part of next week for the western Gulf Coast
including coastal areas of Texas and Louisiana...

...Hot temperatures expected to continue from the Southwest to the Midwest
while expanding gradually east into the Mid-Atlantic...

...Severe weather possible for portions of the central and northern Plains
east to the Great Lakes region...

An area of disturbed weather over the Bay of Campeche has a high
likelihood of developing into a a tropical depression on Sunday or Monday
as the system moves northwestward and then northward near the coast of
northeastern Mexico. A surge of tropical moisture associated with this
along with a surface trough extending north across the western Gulf of
Mexico is expected to allow for heavy showers and thunderstorms to begin
arriving across coastal areas of Texas and Louisiana by late Sunday and
this activity will spread gradually farther inland across the western Gulf
Coast region through the early to middle part of next week. In time,
locally significant rainfall totals will be possible, potentially
resulting in areas of flash and urban flooding. The Weather Prediction
Center has indicated a Slight Risk of excessive rainfall for portions of
Texas and Louisiana to address these concerns, and interests along the
western and northwestern Gulf Coast should monitor the progress of this
system currently over the Bay of Campeche. Please consult the latest
National Hurricane Center Tropical Weather Outlook for more information.

Elsewhere, an expansive dome of upper-level high pressure stretching
across the southern two-thirds of the U.S. mainland will continue to drive
locally very hot temperatures, with the heat encompassing a broad area
from the Southwest to the Midwest, and with the heat expected to advance
east into the Mid-Atlantic region by the start of the new week.
Temperatures will locally be as much as 15 to 20 degrees above normal,
with some of the greatest concentration of this expected to be over the
central Plains. Record high temps will be challenged locally across the
region with some temperatures exceeding the century mark in spots. In
fact, Excessive Heat Warnings have been issued in parts of Arizona and the
Lower Colorado River Valley for both Sunday and Monday. Generally the
coolest temperatures will be confined to the Pacific Northwest and the
northern Plains in the wake of a cold front that will be crossing the
region.

The cold front crossing the Pacific Northwest and northern Plains will be
associated with an upper-level trough, and this energy is expected to
gradually break down the aforementioned ridge of high pressure over of the
southern two-thirds of the nation. As this occurs, a frontal zone with
multiple waves of low pressure advancing along it will be the focus of
scattered to broken areas of heavy showers and thunderstorms. This will
impact a broad area from the central and northern Plains through the
Midwest and into the Great Lakes region. Some severe weather will be
possible locally, and the Storm Prediction Center does have a Slight Risk
of severe weather currently depicted for Sunday across southern New York
and far northern Pennsylvania. A Marginal Risk of severe weather is
highlighted across the central High Plains for both Sunday and Monday, and
in all of these cases, there will be a threat for strong, damaging winds
and some large hail.

Orrison

Graphics are available at www.wpc.ncep.noaa.gov/basicwx/basicwx ndfd.php