Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
405 PM EDT Wed Aug 15 2018

Valid Thu Aug 16 2018 - Sat Aug 18 2018

...A slight risk of severe thunderstorms and flash flooding over parts of
Nebraska and South Dakota...

...A frontal boundary will be the epicenter for excessive rainfall and
strong storms stretching from the Southern Plains into the Ohio Valley
today through Thursday...

...Dry thunderstorms possible across the western U.S....

An deep upper level wave is currently moving across the northern plains,
resulting in complex of showers and thunderstorms across South Dakota and
northern Nebraska. As this area of heavy rain and strong thunderstorms is
expected to continue, the Storm Prediction Center has issued a slight risk
for severe thunderstorms through tonight. The Weather Prediction Center
has also outlined this area as having a marginal to slight risk for
excessive rainfall and flash flooding. This upper level wave will continue
to shift southeast, putting southeast Nebraska, much of eastern Kansas,
and far northwest Missouri in a slight risk for severe storms on Thursday.

A frontal system is currently stretching from the Southern Plains
northeast towards the Great Lakes and across the Northeast. Warm, moist
air is being pumped northward from the Gulf of Mexico towards this frontal
boundary, especially across the Southern Plains and Low/Middle Mississippi
Valley. This is resulting in an unstable atmosphere capable of producing
strong storms and excessive rainfall. The Weather Prediction Center have
outlined two areas as being in a slight risk for excessive rainfall and
flash flooding through tonight. The first encompasses the northwest
portion of the Southern Plains (including the Oklahoma and Texas
panhandles), and the second stretches from far eastern Oklahoma into
southern Indiana and along the Ohio River of Kentucky. Furthermore, a
portion of West-Central Arkansas and far East-Central Oklahoma is in a
moderate risk for flash flooding. Flash flood watches and warnings are
ongoing across this moderate risk region, stretching northward into the
Southern Missouri. The Storm Prediction Center has also placed these same
regions in a moderate risk of severe weather development. As the frontal
boundary slowly shifts eastward over the coming days, so too with the risk
for excessive rainfall and strong storms.

Meanwhile the western U.S. is still being impacted by fire weather
concerns. Monsoonal moisture is currently making its way into the
Southwest. However, as this moisture surges northward across the western
U.S., a very dry near-surface layer will likely prevent any rainfall from
hitting the ground. Furthermore it will likely result in dry
thunderstorms, with lightning potentially sparking new wildfires. Red Flag
warnings are in effect across central Oregon, northeast California,
western Nevada, and southwest Wyoming through this evening. Air Quality
Alerts are also encompassing large portions of the western U.S. as ongoing
wildfires continue to infuse the air with copious amounts of smoke. Much
of Washington, Oregon, northern Idaho, and western Montana, as well as a
portion of Central California are included in an Air Quality Alert. An Air
Quality Alert for blowing dust has also been issued near and around
Phoenix, Arizona through Thursday.


Graphics available at
Storm Prediction Center United States 2 Day Forecast