Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
358 PM EDT Fri May 19 2023

Valid 00Z Sat May 20 2023 - 00Z Mon May 22 2023

...Severe thunderstorms and flash flooding possible for the Southern
Plains into the Lower Mississippi Valley this evening, shifting eastward
on Saturday...

...Well above average, record-breaking warmth continues for interior
portions of the Northwest through Saturday, some moderation on Sunday...

The upper level pattern will be feature general troughing in the eastern
U.S. and ridging for the West heading into the weekend. A progressive
upper level disturbance will track from the Great Lakes today into New
England this weekend which will be accompanied by a cold front at the
surface. Meanwhile, a surface low along the southern Mid-Atlantic coast
this afternoon will track northward through Saturday and weaken, bringing
a surge of deep moisture northward into southern/eastern New England.
These two features will ensure a wet Saturday for many from New York and
Pennsylvania into New England. A broad one to two inches of rain is
expected from New York City/Long Island into southern and eastern New
England along with isolated flash flooding before more pleasant conditions
return on Sunday.

Farther south along the cold front, from the lower/middle Mississippi
Valley into the Ozarks and Texas, severe thunderstorms and flash flooding
will be possible through this evening with the threats extending into
early Saturday morning. As the cold front moves eastward during the day on
Saturday, the threats for severe thunderstorms and flash flooding will
shift eastward into the Gulf Coast states and Tennessee Valley but the
concerns for adverse weather do not look to be as widespread when compared
to today/Friday.

Upper level ridging over the western U.S. will continue on Saturday with
high temperatures forecast to range 15-25 degrees above average for much
of the interior Northwest. Daily record high temperatures will be possible
for portions of Washington, Oregon, Idaho, possibly extending into western
Montana and northern California. A Pacific trough will move into the
Northwest on Sunday which will have the effect of reducing high
temperatures a bit for Washington and Oregon but spread the above average
warmth into the north-central U.S. Isolated record highs are possible on
Sunday for the interior Northwest, but the greatest potential for record
breaking heat is expected to be on Saturday. In terms of precipitation,
scattered afternoon/evening thunderstorms will occur in areas of terrain
with more widespread coverage in the vicinity of the Four Corners region
near a weak upper level disturbance. The remainder of the West should
remain dry.

Otto

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