…Threat for flash and urban flooding this week over the Florida
Peninsula as rich tropical moisture overspreads the region…
…Moderate to locally heavy rainfall continues with storms in Texas;
severe storms forecast for the Upper Midwest later Wednesday…
…Heat-related Advisories/Warnings in place for the central California
Valleys and portions of the Southwest as temperatures soar into the 100s…
A very stormy and wet week is in store for the Florida Peninsula as a
steady plume of rich, tropical moisture from the western Caribbean begins
to overspread the area ahead of a quasi-stationary frontal boundary draped
just to the north. Multiple rounds of intense downpour producing storms
(rain rates of 2″+ per hour) are expected not only through the current
forecast period (Wednesday evening), but are likely to continue into the
weekend. Slight Risks (level 2/4) of Excessive Rainfall are in effect both
Tuesday and Wednesday for the threat of flash flooding, particularly for
urban areas, and a higher threat level may be necessary if confidence in
day-to-day storm locations increases. While antecedent conditions are dry
in the region, the threat outside urban areas may also increase with each
day as the heavy rainfall begins to lead to wetter soils more susceptible
to flooding. Further west, additional storms are expected along the
boundary along the immediate Gulf Coast and into portions of Texas the
next couple of days. While the available moisture will not be as high and
rain rates/totals are not forecast to be as heavy as further east, there
will still be an isolated risk of flash flooding, most likely over central
Texas. The Storm Prediction Center has also included a Slight Risk of
severe thunderstorms (level 2/5) over the Edwards Plateau Tuesday where
some of the more intense storms could produce some large hail and damaging
winds.
Showers and thunderstorms continue ahead of a frontal system passing
through the northern/central Plains this evening. The system will lift
northeastward into the Upper Midwest Tuesday with some showers and storms
expected, though totals will likely remain light to moderate as storm
coverage/intensity decreases. Another system will approach and move into
the Pacific Northwest early Tuesday and pass through the northern Rockies
by Wednesday, though little to no precipitation is expected across the
region. As the system enters the northern Plains/Upper Midwest by
Wednesday afternoon, better moisture streaming northward will bring a
greater chance of thunderstorms. The SPC has included a Slight Risk over
portions of the Upper Midwest for the threat of very large hail and
damaging winds.
Much of the West will remain well-above average this week as an
upper-level high begins to build in over the Southwest and northern
Mexico. The greatest threat from the heat will stretch from the central
California valleys into portions of southern Nevada/Arizona Tuesday before
expanding even further east into southern New Mexico and far west Texas by
Wednesday. Here, heat-related advisories and warnings are in place as
temperatures soar well into the 100s and nighttime lows in the 70s and low
80s provide little relief. The risk from the heat is characterized as
‘Major’ (level 3/4) which considers impacts that will be felt by the
entire population that are without effective cooling or adequate
hydration, not just those individuals more sensitive to heat. Much above
average temperatures will also spread into portions of the north-central
U.S. by Wednesday, with many highs in the upper 80s to mid-90s from the
central/northern Plains into portions of the Upper Midwest. Meanwhile,
temperatures will begin to warm-up and return closer to normal over the
next couple of days for much of the Interior Northeast/Ohio Valley
following many highs in the 60s Monday. Most of the eastern/southern U.S.
will be near average with highs in the 70s/80s for the Northeast, 80s in
the Mid-Atlantic, and 80s and 90s from the Southern Plains into the
Southeast.
Putnam
Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php