Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Tue Sep 16 2025

Valid 12Z Tue Sep 16 2025 - 12Z Thu Sep 18 2025

...Slow-moving coastal low to bring heavy rain potential along the
Mid-Atlantic coast...

...Heavy rains possible across the Central to Northern Plains Tuesday and
Wednesday...

...Tropical moisture from Mario to begin to push into Southern
California...

...Below average temperatures likely where wet weather occurs next two
days, otherwise above average temperatures expected across much of the
CONUS...

The large scale mid- to upper-level flow across the Lower 48 is becoming
increasingly amplified, resulting in slow-moving systems affecting the
CONUS.  Along the Mid-Atlantic coast, complex interaction between a low
pressure system developing over the warm Gulf Stream and a cold
upper-level low centered over the interior Mid-Atlantic is forecast to
steer the low pressure system northwestward into the eastern shores of
North Carolina and Virginia today.  A swath of moderate to heavy rain has
developed near the Mid-Atlantic coast early this morning and has begun to
expand farther inland.  Meanwhile, deeper thunderstorms and heavy rain
forming just offshore near the circulation center of the system is
forecast to push onshore across the eastern shores of North Carolina to
Virginia during the day today.  The system is forecast to stall tonight
into much of Wednesday over eastern Virginia to eastern North Carolina. 
The slow and meandering movement of the system will support potential for
additional heavy rainfall amounts across northeast North Carolina into
southeast Virginia and the southern Delmarva Peninsula with two day totals
of 2-5" possible.  Note that these areas have been dry over the past month
or two with much of the area in DO (abnormally dry) drought conditions.

Across the mid-section of the country, rounds of heavy rain associated
with clusters of thunderstorms can be expected today into Wednesday across
large sections of the central to northern Plains in response to a mid- to
upper-level system pushing out of the northern Rockies.  From Wednesday
into Thursday, a low pressure system is forecast to become more
consolidated over the north-central U.S.  Showers and thunderstorms will
increase in coverage today and especially on Wednesday across the central
to northern Plains, with these showers/thunderstorms continuing into
Thursday as the system will be moving rather slowly.  These rains will
bring relief to areas of western Nebraska and southern South Dakota that
are experiencing abnormally dry (D0) to moderate drought (D1) conditions. 
The remainder of the central to northern Plains that may receive heavy
rains are not in drought conditions due to greater rains over the past few
months.

Tropical Storm Mario, currently moving northwestward well off the west
coast of the Baja, will begin to bring upper-level moisture into southern
California, southern Arizona and southern New Mexico later today.  While
Mario is forecast to weaken as it moves northwestward, the tropical
moisture ahead of the system may bring showers into far southern coastal
California and the offshore islands Wednesday, with these showers pushing
farther north into much of southern California on Thursday. 

Temperature wise across the lower 48, much of the CONUS will see above
average temperatures over the next few days in the last full week of
summer.  Exceptions to this will be in the above-mentioned regions where
heavy precipitation is possible, across the Mid-Atlantic Tuesday and
Wednesday, and across the central to northern Plains Wednesday into
Thursday where below average temperatures are likely due to this heavy
rain potential.

Kong/Oravec

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