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