Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
411 PM EDT Wed Aug 17 2022
Valid 00Z Thu Aug 18 2022 - 00Z Sat Aug 20 2022
...Flash flood risk intensifies in the Southwest as an already active
Monsoon season ramps up...
...Showers and thunderstorms remains persistant across the Southeast and
...Hot weather continues for California and the Northwest with numerous
heat advisories in place...
The flash flood risk across the Southwest associated with an already
active Monsoon season will increase further over the next couple of days
as a mid-level low associated with a former tropical wave leads to an
increase in moisture and instability on top of the Monsoonal moisture
already in place. There is a Slight Risk of Excessive Rainfall Thursday
for portions of southwestern Utah and Arizona for areal average rainfall
totals between 0.5-1", with locally higher totals possible across far
southern Arizona closer to the influence of the mid-level low. The threat
increases Friday for potentially much more siginficant rainfall, and a
Moderate Risk has been issued for southeastern Arizona and southwestern
New Mexico. Areal average rainfall totals increase to 2"+, a notably high
amount for a widespread area which may lead to major flood-related impacts.
Meanwhile, persistant shower and thunderstorm chances continue from the
Southeast to the Southern Plains along a wavey stationary front which will
remain in the area through the end of the forecast period. There is a
Slight Risk of Excessive Rainfall for portions of southeastern Georgia as
well as southeastern Louisiana and southern Mississippi where more
continuous rounds of storms and high rain rates may lead to locally
heavier rainfall totals of 3"+ and a few instances of flash flooding.
Outside of the heavy rainfall threat, hot weather will remain in place
across California and the Northwest under the influence of an upper-level
ridge. There are numerous heat-related advisories in effect for the
central Valleys of California, most of the interior Pacific Northwest, and
the nothern Great Basin as highs reach into the upper 90s and low 100s
Thursday and Friday. The heat threat will be most intense across the
Colubmia River Valley in central Washignton where highs up to 105 and lows
dropping only into the upper-60s and low 70s are up to 20 degrees above
normal for the region. The urban areas from Seattle south to Portland will
also see hot temperatures in the mid- to upper 90s Thursday before an
upper-level trough approaches from the Pacific and the ridge shifts
eastward, providing a return to more normal temperatures Friday and a
break from the heat.
Elsewhere, high temperatures approaching 100 along with high humidity will
lead to heat indices around 110 for portions of southeastern Texas
Thursday while highs will be around normal for the Plains and Midwest.
Persistant clouds and some rain will lead to much cooler highs in the 60s
in New England as a low pressure system departs northeastward into Canada.
On Friday, a cold front moving southward through the Plains will drop
temepartures into the 70s for the Northern Plains while warmer highs
approaching 90 return to the Mid-Atlantic and southern New England.
Graphics are available at