The Nation’s Weather

…A strengthening low pressure system will bring moderate to heavy rain
and gusty winds from the Ohio Valley to the Mid-Atlantic states this
evening into tonight, then to New England and the interior Northeast on
Saturday…

…Severe thunderstorms likely this evening for parts of the Mid-Atlantic
and the Southeast…

…Significant heat expected across interior California and portions of
the Southwest through Saturday…

A strengthening low pressure system will track across the northern
Mid-Atlantic through the evening and overnight hours, reaching New England
and the interior Northeast by Saturday. A complex of thunderstorms with
moderate to heavy rain along with increasingly gusty winds can be expected
along the track of this storm system. The highest chance of heavy rain
will be across the Ohio Valley this afternoon an evening and then into the
northern Mid-Atlantic by tonight. Some thunderstorms will also have the
potential to become strong to severe, possibly resulting in damaging
winds, hail, isolated tornadoes, and scattered instances of flash
flooding. The severe thunderstorm potential also extends southward into
portions of the southern Mid-Atlantic and the Southeast, particularly
across the Carolinas and parts of eastern Georgia. The low is forecast to
deepen further as the center tracks northeastward through New England on
Saturday with a swath of moderate to heavy rain across the interior along
with gusty winds expanding across the Northeast. While the initial cold
front will be well off the East Coast by Saturday, the instability
associated with a cold upper-level trough could trigger additional
scattered thunderstorms across the Mid-Atlantic region Saturday afternoon,
even though temperatures will be cooler in the wake of the front. Saturday
night into Sunday morning, a reinforcing cold front will bring anomalously
cool temperatures from the Great Lakes through the Northeast and down into
the Mid-Atlantic, setting up a fairly pleasant Sunday to round out the
weekend.

Meanwhile, in contrast to the rain and cooling trend in the eastern U.S.,
a strong ridge of high pressure will bring heat and persistent dry weather
across much of the western U.S. and into the northern Plains. In fact,
record high temperatures will be threatened across interior northern
California this afternoon, expanding into the Great Basin, Idaho, and as
far north as western Montana on Saturday. The anticipated dangerous heat
in the Southwest for the next couple of days has led to the issuance of
Extreme Heat Warnings for portions of southernmost Nevada, southeast
California, and northwestern most Arizona. Drinking plenty of water,
wearing light colored clothing, and staying in air conditioned areas is
advised as temperatures soar as high as the mid-110s Fahrenheit in lower
desert locations like Death Valley, California. A cold front from the
Pacific is forecast to bring rapid cooling into the Pacific Northwest
later Saturday into Sunday but with minimal rainfall expected. Farther
south and east, surging moisture ahead of the front across parts of the
Rockies and Intermountain West will support high elevation showers and
thunderstorms Sunday afternoon and evening. Given the enhanced moisture
being drawn in, some of these showers and storms could produce briefly
heavy downpours.

Miller/Kong

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