Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
352 AM EDT Fri Aug 18 2023

Valid 12Z Fri Aug 18 2023 - 12Z Sun Aug 20 2023

...Heavy rainfall and flash flooding becoming more likely over parts of
the Southwest...

...Critical fire conditions expected from the Northwest to the northern
High Plains today...

...Dangerous heat redeveloping over the central U.S.....

Monsoonal moisture along with tropical moisture associated with Hurricane
Hillary will begin to increase thunderstorm coverage across portions of
the Southwest today, with heavy rainfall and flash flooding possible.  As
Hillary continues to track north in the eastern Pacific near Baja
California, the threat for heavy rainfall and flash flooding is likely to
increase on Saturday, especially for portions of Southern California,
western Arizona, and southern Nevada.  With the increase in cloud cover,
temperatures will return to more seasonal values today before dropping
below normal across much of Southern California, western Arizona, and the
Great Basin over the weekend.

Farther to the north, an area of low pressure is forecast to strengthen
over the Canadian Prairie.  Windy and mostly dry conditions to its south
and southwest will lead to critical fire conditions extending from the
Inland Northwest to northeastern Montana today.

Over the central U.S., dangerous heat will continue to intensify with
well-above normal to record-breaking temperatures expected from the
central Gulf Coast and lower Mississippi Valley to the northern High
Plains today.  This heat will persist from the southern Plains to the
central Gulf Coast into the weekend while building across the central
Plains and shifting east across the northern Plains into the upper
Midwest.  However, a cold front trailing the previously noted low over
Canada will bring relief to the northern High Plains over the weekend.

In the eastern U.S., showers and thunderstorms with areas of heavy
rainfall will accompany an area of low pressure and its cold front as they
move across the Northeast today.  Behind the front, high pressure with
seasonal to below-average temperatures will move from the Great Lakes and
Ohio Valley into the Northeast and Mid-Atlantic states today and Saturday.
 The front is forecast to stall across the Southeast, where seasonal to
above-normal temperatures are forecast into the weekend.
   
Pereira

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