Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
249 PM EDT Wed Jun 23 2021

Valid 00Z Thu Jun 24 2021 - 00Z Sat Jun 26 2021

...Much above average temperatures expected over the Northwest, leading
into a likely record hot weekend...

...Widespread Heavy Rains, localized Flash Flooding and Severe
Thunderstorms possible Thursday and Friday from the Central Plains, into
the Mid Mississippi Valley and Great Lakes region...

...A Fire Weather Threat from Lightning Thursday and Friday across
northern California, the Great Basin and the Southwest...

...Wet Season weather across Florida over the next two days will provide
relief from dry conditions...

An increasingly amplified mid to upper level pattern across the northeast
Pacific will be leading to a building upper High across southwest Canada
and into the Pacific Northwest.  This will be setting the stage for the
beginning of a potential historic heat wave for the Northwest this
weekend.  While record high temperature are not expected over the next two
days over the Northwest, the high temperatures will still be 10 to 20
degrees above average and lead into the weekend when numerous record highs
are likely. Excessive Heat Watches are currently in effect across all of
Washington State, much of Oregon and into far northern California. 

Above average temperatures also likely through much of the Plains
Thursday, with a significant cool down likely for portions of the Northern
and Central High Plains on Friday as a cold front presses southward across
these regions.  High temperatures Thursday are forecast to be 10 to 15
degrees above average, followed by highs Friday 10 to 15 degrees below
average across these regions.

The frontal boundary providing relief from hot temperatures over the
Northern to Central High Plains on Friday will also be a focus for
widespread heavy rains, localized flash flooding and a severe
thunderstorms threat both Thursday and Friday from the Central Plains,
northeastward into the Middle Mississippi Valley and Great Lakes region.
Much above average levels of moisture along and ahead of this front and
the expected very slow movement of the front will support the active
thunderstorm pattern and potential for heavy rains, flash flooding and
severe weather.

A well defined mid to upper level low off the central California coast is
expected to move only slowly eastward over the next two days. This system
will transport above average levels of moisture to its east and northeast
supporting increased scattered thunderstorm activity from northern
California, eastward into the Great Basin and portions of the Southwest. 
There is not expected to be much rainfall from these "dry" thunderstorms
but lightning will still be active.  This will pose a threat of lightning
induced wild fires over the next 2 days across these areas.

Across Florida, a wet season weather pattern will be in place over the
next several days. This will bring the potential for heavy rains across
the state, especially the central to southern portions of the peninsula. 
These rains will provide relief to portions of the peninsula that are
currently experiencing abnormally dry to moderate drought conditions as
per the latest Drought Monitor.

Oravec