Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
441 AM EDT Sun Jul 16 2023

Valid 12Z Sun Jul 16 2023 - 12Z Tue Jul 18 2023

...There is a Moderate Risk of Excessive Rainfall for parts of the
Northeast today with the potential for significant flash flooding, Slight
Risk of severe storms in southern New England...

...Various areas of heavy showers and thunderstorms throughout the East &
South, including parts of southern Arizona...

...Excessive Heat Warnings and Heat Advisories persist from the Pacific
Northwest, California, and the Great Basin to parts of the Southern
Plains, Central Gulf Coast, and South Florida...

...Air Quality alerts over parts of the Northern High Plains, Midwest, and
Great Lakes...

As day breaks on this Sunday, July 16, copious amounts of moisture
streaming ahead of a cold front slowly approaching from the west will
ignite numerous heavy showers and storms from the Mid-Atlantic to the
Northeast. These storms will be capable of producing torrential rainfall
rates and may also coincide within training areas of thunderstorms. Given
some parts of the Northeast contain saturated and sensitive soils from
recent heavy rainfall over the past 10 days, this is a setup primed to
produce flash flooding that could be significant in affected areas. The
Weather Prediction Center (WPC) has issued a Moderate Risk from the
Delaware Valley on north and east into central New England. The Moderate
Risk does include the NYC, Philadelphia, Hartford, and Boston metro areas.
Potential impacts as a result of flooding include impassable roadways,
swiftly flowing creeks and streams, and in higher terrain locations,
possible mudslides. The Slight Risk area extends from the Virginia
Tidewater on north to northern Maine. The Storm Prediction Center (SPC)
also issued a Slight Risk for severe weather from the NYC metro area on
east to include all of southern New England. Severe storms within the
Slight Risk area have the may produce damaging wind gusts and tornadoes.

While the Northeast faces the more significant threat for flash flooding
today, there are no shortage of other areas that are also at-risk for both
Excessive Rainfall and severe weather. Today, SPC has a Slight Risk of
severe storms in the Central Plains. Both WPC and SPC have Marginal Risks
for Excessive Rainfall and severe storms that stretch from the Central
Plains to the Middle Mississippi Valley. Both National Centers also
feature Marginal Risk areas for the ArkLaTex and along portions of the
Gulf Coast. By Monday, the threat for severe storms and excessive rainfall
becomes more scattered across the country. SPC posted a Slight Risk for
severe weather in southern South Dakota and northern Nebraska with a few
Marginal Risks areas; one in the north-central Plains, one in central
Montana, and the other in the Ohio Valley. When it comes to Excessive
Rainfall, areas from the eastern Great Lakes on south to the Tennessee
Valley could witness storms possibly cause areas of flash flooding. There
are also Marginal Risks in Florida, the central Gulf Coast, and even
southern Arizona.

Speaking of Arizona, "The Grand Canyon State" and many of its neighboring
states in the West will continue to contend with an ongoing dangerous heat
wave. In total, from South Florida and the Gulf Coast to the Southwest,
over 80 million people remain under either an Excessive Heat Warning or
Heat Advisory as of early this morning. In the Southwest today, daytime
highs will approach the century mark in the interior Northwest, range
between 100-110F throughout interior California and the Great Basin, and
even top 115F in parts of the high desert of southern California, southern
Nevada, and southern Arizona. Widespread record breaking high
temperatures, as well as record breaking warm daily minimums are expected
in parts of the Southwest, along the western Gulf Coast, and in South
Florida. By Monday, the core of record breaking heat shifts more into the
Four Corners states with parts of South Texas and South Florida still
seeing possible record heat. The combination of sizzling temperatures and
oppressively high dew points will result in sultry heat throughout the
South into the upcoming week. For more information regarding both ongoing
and potential impacts from this heat wave, please visit heat.gov.

In addition to the flooding/severe threats and stifling heat, Air Quality
alerts are in place for much of the Great Lakes, Midwest, and northern
High Plains. This is due to the lingering thick concentration of Canadian
wildfire smoke over these regions. While the concentration of smoke in the
atmosphere should begin to wain by Monday, there is still enough smoke to
support unhealthy air quality that is unhealthy for sensitive groups in
parts of these regions into the start of the upcoming week.

Mullinax


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