Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
440 AM EDT Sat Oct 18 2025

Valid 12Z Sat Oct 18 2025 - 12Z Mon Oct 20 2025

...Heavy rain and severe thunderstorms expected to impact portions of the
ArkLaTex, Mid-South, Ohio Valley, and Great Lakes later today into Sunday,
reaching the East Coast Sunday night...

...Turning colder and unsettled across the Pacific Northwest and northern
Rockies with coastal and valley rain along with mountain snow and gusty
winds...

An increasingly active weather pattern that signals the emergence of La
Nina is forecast for the U.S. through the weekend into early next week.  A
deepening upper trough and a cold air mass from western Canada force their
way eastward will clash with a cold front across the mid-section of the
country.  The vigorous dynamics associated with this interaction is
forecast to produce a rapidly intensifying low pressure system to track
from the Midwest tonight and then through the Great Lakes Sunday morning. 
A potent cold front trailing south from the cyclone center will be
preceded by an outbreak of severe weather across much of the mid to lower
Mississippi Valley from later today through tonight per the Storm
Prediction Center.  The main hazards to watch for will include damaging
winds, large hail, and tornadoes with the strongest storms that develop. 
In addition, thunderstorms will have the potential to produce heavy
rainfall rates especially across parts of northern Arkansas, southern
Missouri, and southern Illinois by later today into tonight.  The relative
fast forward motion of the cold front will help limit the total rainfall
amounts.  Nevertheless, the high rain rates associated with the severe
thunderstorms are expected to warrant a Slight Risk of flash flooding
across portions of southern Missouri into southern Illinois through
tonight.  Elsewhere, intense downpours can be expected to accompany
thunderstorms that are expected to become severe across the lower
Mississippi Valley and as far north as the lower Great Lakes by this
evening into the overnight hours.

By Sunday night, the center of the rapidly intensifying cyclone will
quickly exit into southern Canada.  However, the potent cold front
trailing south from the cyclone will sweep across the east-central U.S.
and the Deep South with a round to possibly several rounds of strong to
severe thunderstorms.  Meanwhile, a swath of moderate to locally heavy
rain will accompany the passage of the cyclone across the Great Lakes on
Sunday.  From Sunday night into Monday morning, a squall line could be
sweeping through the entire East Coast with a round of strong to severe
thunderstorms ahead of the cold front.  By Monday morning, the most active
weather should be found across New England where strong thunderstorms and
locally heavy rain could be sweeping across as a new low pressure system
begins to develop.

Behind the rapidly intensifying cyclone in the East, strong and gusty
northwesterly winds will make for a breezy day across the mid-section of
the country on Sunday as a colder air mass from Canada filters into the
region.  However, a rapid warm-up is forecast for the High Plains on
Sunday, spreading into the southern Plains by Monday ahead of another
rapidly developing low pressure system that will sweep across the Pacific
Northwest on Sunday and into the northern Plains by Monday morning.  This
system will signal the arrival of unsettled weather beginning today
through the weekend for the Pacific Northwest.  By Sunday, high-elevation
snow is expected to push further inland across Idaho and then through the
northern Rockies Sunday night into Monday morning along with gusty winds. 
Meanwhile, the Southwest and the Four Corners will remain dry with a
gradual warming trend.

Kong


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