The Weather Prediction Center

Short Range Forecast Discussion

[Abbreviations and acronyms used in this product]
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Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Wed Jul 28 2021

Valid 12Z Wed Jul 28 2021 - 12Z Fri Jul 30 2021

...There is a Moderate Risk of severe thunderstorms over parts of
the Upper Mississippi Valley, Upper Great Lakes, and parts of the
Ohio Valley through Thursday morning...

...There is a Slight Risk of excessive rainfall over parts of the
Upper Mississippi Valley/Upper Great Lakes through Thursday
morning...

...There is a Slight Risk of excessive rainfall over parts of the
Southwest Thursday into Friday morning...

...Heat Advisory over parts of the Mississippi Valley and the
Plains; Excessive Heat Warning over parts of the Northwest...

A front extending from the northern Mid-Atlantic across the Ohio
Valley into the Upper Midwest will have a wave of low pressure
traveling along the boundary through Thursday. As a result,
showers and thunderstorms will develop along and near the boundary
through Thursday evening. Some of these thunderstorms will become
severe with more robust dynamics.  Therefore, the SPC has issued a
Moderate Risk of severe thunderstorms over parts of Upper Great
Lakes through Thursday morning.  The hazards associated with these
thunderstorms are frequent lightning, severe thunderstorm wind
gusts, hail, and a few tornadoes. There is a 10% or greater
probability of wind gust of 65 knots or greater and a 10% or
greater probability of two-inch or great hail over parts of the
Upper Mississippi Valley/Upper Great Lakes through Thursday
morning.  Furthermore, there is a 10% or greater probability of
EF2-EF5 over parts of the Upper Mississippi Valley/Upper Great
Lakes through Thursday morning.

Additionally, the thunderstorms will produce heavy rain. 
Therefore, the WPC has issued a Slight Risk of excessive rainfall
with these thunderstorms over parts of the Upper Mississippi
Valley, Upper Great Lakes, and parts of the Ohio Valley through
Thursday morning.  The associated heavy rain will create mainly
localized areas of flash flooding, with urban areas, roads, and
small streams the most vulnerable.

Showers and thunderstorms will continue along and near the
boundary through Friday. The severe thunderstorm threat shifts to
the Ohio Valley, Mid-Atlantic, Central Appalachians, and Northeast
Thursday into Friday morning.  The excessive rainfall threat
decreases slightly on Thursday into Friday morning.

Meanwhile, showers and thunderstorms will continue over the
Southwest, Central/Southern Rockies, and Great Basin today, though
the excessive rainfall threat will be lower. However, the
monsoonal moisture streams back into the Southwest as strong
upper-level energy passes over the region Thursday into Friday.
Therefore, the WPC has issued a Slight Risk of excessive rainfall
over the Southwest on Thursday into Friday morning. The associated
heavy rain will create mainly localized areas of flash flooding,
with urban areas, roads, and small streams the most vulnerable.

Over the Northwest, there is an Excessive Heat Warning over parts
of the area, where temperatures will be above average.
Furthermore, Heat Advisories are currently in effect for portions
of the Mississippi Valley and the Plains where the temperatures
will be 10 to 20 degrees above average.  Moreover, several regions
have Air Quality Alerts due to wildfires over the Northwest into
the Northern Rockies.

Ziegenfelder
	


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




Last Updated: 400 AM EDT Wed Jul 28 2021