Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 PM EDT Fri Sep 22 2023

Valid 00Z Sat Sep 23 2023 - 00Z Mon Sep 25 2023

...Tropical Storm Ophelia is forecast to make landfall over eastern North
Carolina early on Saturday, bringing squally heavy rain, threat of flash
flooding farther inland, and storm surge to coastal communities up the
Mid-Atlantic states...

...Bouts of strong to severe thunderstorms are expected to impact portions
of the central U.S., including chances for excessive rainfall...

...Summer heat continues across portions of the southern Plains, while
much cooler temperatures begin to moderate throughout the Intermountain
West and northern Rockies...

The National Hurricane Center has upgraded the developing low pressure
system off the coast of the southeastern U.S. to Tropical Storm Ophelia
early this afternoon.  Tropical-storm-force winds associated with Ophelia
is more expansive than an ordinary tropical storm as the core of the
system moves generally northward over the warm waters off the Carolina
coasts through tonight, while undergoing continued interaction with a
frontal boundary and a cool upper trough sliding off the southeast U.S.  A
dreary and windy weekend is in store for much of the Mid-Atlantic
especially along the coast where the full force of the
tropical-storm-force winds will be felt.  Coastal flooding due to storm
surge will become an increasing concern as tonight progresses and
especially along the coast of the eastern half of North Carolina early on
Saturday when Ophelia is expected to be the strongest as it makes
landfall.  Meanwhile, the strongest upper-level dynamics associated with
Ophelia is forecast to dump the heaviest rains to the north and northwest
of the circulation center--from much of the Mid-Atlantic and eventually up
into southern New England, creating the potential for scattered flash
floods and isolated urban and small stream flooding.  The greatest risk
for several inches of rainfall will most likely be near and just west of
the storm track from North Carolina into southeastern Virginia, across
eastern Maryland and Delaware, and then across southern New Jersey.  By
Sunday, Ophelia is forecast to become much weaker as it inches northward
over the Chesapeake Bay and the Delmarva Peninsula and gradually lose
tropical characteristics.  Some additional heavy rainfall may linger from
the northern Mid-Atlantic to southern New England, with continued strong
and gusty east-northeasterly flow along coastal regions.

Throughout the central U.S., a potent system ejecting out of the Rockies
and coming to a crawl over the Mississippi Valley this weekend is
anticipated to trigger widespread shower and thunderstorm chances.  Some
storms may turn severe into tonight across the northern and central High
Plains, with the severe threat becoming more widespread on Saturday from
the Middle Missouri Valley to the Southern Plains near and ahead of an
elongated low pressure system.  Heavy rain is also possible on the
northern quadrant of this storm system through tonight across the northern
Plains before shifting east and southeast, overlapping with the severe
weather threat area on Saturday.  Some repeating rounds of thunderstorms
could produce a few inches of rainfall within a short period of time,
leading to scattered flash flooding concerns.  Meanwhile, high-elevation
wet snow over northwestern Wyoming on the back-side of this system is
forecast to taper off by Saturday morning.

The temperature outlook for the final full weekend of September is
highlighted by below average temperatures across the Mid-Atlantic,
Northeast, and western third of the Nation. In fact, conditions are likely
to be cold enough over the northern Rockies to produce snow across the
highest elevations. Elsewhere, summer continues to hang on across the
southern Plains as above average temperatures and highs into the upper 90s
remain in the forecast. Afternoon temperatures should peak in the low 100s
along the U.S.-Mexico border. Thankfully, looking further ahead, a cold
front approaching by the end of the weekend is expected to knock
temperatures closer to average by Monday, with only South Texas likely
remaining well above average.

Kong/Snell


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