Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
359 PM EDT Sun Sep 26 2021

Valid 00Z Mon Sep 27 2021 - 00Z Wed Sep 29 2021

...There is a Marginal Risk of excessive rainfall over parts of the
Southwest through Tuesday morning...

...Temperatures will be 10 to 25 degrees above average over parts of the
Northern/Central Plains, Great Basin, Middle Mississippi Valley, and
Northern Rockies...

...There is a Critical Risk of fire weather over parts of the Central
Plains and an Elevated Risk over portions of California, Nevada, and
Oregon...

Upper-level low and moisture over the Southwest will aid in producing
widely scattered showers and thunderstorms over the area through Tuesday.
Some of the thunderstorms will produce heavy rain, but this will be
isolated.  Therefore, the WPC has issued a Marginal Risk of excessive
rainfall over parts of the Southwest through Tuesday morning.  The
associated heavy rain will create localized areas of flash flooding,
affecting areas that experience rapid runoff with heavy rain. The
upper-level low will slowly move northeastward to the Central Rockies by
Tuesday.  Moisture will flow northward over the Southern/Central Plains
Monday into Tuesday, setting the stage for showers and thunderstorms to
develop over parts of the Central and Southern Plains on Monday evening
and Tuesday evening.

Meanwhile, a front extending across the Upper Midwest will slowly move
eastward to the Northeast/Mid-Atlantic Coast westward to the Middle
Mississippi Valley by Tuesday. Showers and thunderstorms will develop
along and ahead of the front starting on Monday afternoon over parts of
the Lower Great Lakes into the Northeast that will settle into parts of
the northern Mid-Atlantic and Southern New England by Tuesday.

In the meantime, a front will move onshore over the Pacific Northwest by
Monday morning, moving inland to the Northern High Plains to the Great
Basin by Tuesday.  The system will start producing rain over parts of the
Northwest overnight Sunday and slowly move over parts of Northern
California by late Monday morning.  The rain will continue to march inland
to the Northern Intermountain Region by late Monday while continuing over
the Pacific Northwest through Tuesday.

Additionally, upper-level ridging ahead of the boundary will allow
temperatures to become 10 to 25 degrees above average over parts of the
Northern/Central Plains, Great Basin, Middle Mississippi Valley, and
Northern Rockies over the Northern Rockies.  The warm temperatures and
gusty wind led to conditions favorable for a Critical Risk of fire weather
over parts of the Central Plains and an Elevated Risk over parts of
California, Nevada, and Oregon through Monday morning.  Therefore, Red
Flag Warnings are up over portions of California, Nevada, and Oregon.  Red
Flag Warnings are also up over parts of the Northern Rockies and the
Central/Southern Plains.  Furthermore, weak high pressure at the surface
and upper-level ridging over California will create light wind over the
San Joaquin Valley provides stagnant airflow. Therefore, Air Quality
alerts are over parts of California due to wildfire smoke through Monday.

Ziegenfelder


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