Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
357 PM EDT Tue Aug 20 2019
Valid 00Z Wed Aug 21 2019 - 00Z Fri Aug 23 2019
...Strong to severe thunderstorms possible Tuesday afternoon and evening
across portions of central Plains, Ohio valley and Mid-Atlantic...
...Dangerous heat is expected for the Desert Southwest and across the
midsection of the country as warmth persists across the bulk of the U.S....
A well-defined convective complex continues to advance from the mid
Mississippi into the Ohio valley, producing showers and thunderstorms and
areas of damaging winds and large hail. It is expected that severe
weather will remain a threat as the system moves farther south and east
across the Ohio valley Tuesday afternoon and evening.
Farther east, expect showers and thunderstorms to continue to develop
Tuesday afternoon ahead of a weaker system moving across the central
Appalachians into the Mid-Atlantic region. Conditions are favorable for
some of these storms to become strong to severe - producing damaging winds
and large hail.
Additional storms are forecast to develop Tuesday evening into the
overnight hours over the central High Plains and along a strong frontal
boundary sagging south into the central Plains. There is the potential
for these storms to become strong to severe as well, with large hail and
damaging winds the primary threat.
As low pressure strengthens over eastern Canada, the leading edge of this
front is expected to push east across the Great Lakes, with showers and
thunderstorms developing along and ahead of the front. Severe storms will
remain a concern, especially across portions of the northern Mid-Atlantic
into the Northeast, where a weak upper level disturbance moving from the
lower Great Lakes toward New England is expected to encourage storm
development. Additional storms are also possible along and south of the
front as it extends from the Northeast back through the Ohio valley into
the central High Plains on Wednesday. Across portions of the central
Plains into the lower Missouri and mid Mississippi valley, conditions will
be favorable for heavy rainfall rates, which may result in flash flooding
across portions of the region.
Ahead of the front, seasonal to above-average temperatures will persist
across much of the South and the East Coast through midweek. Dangerous
heat and humidity has resulted in excessive heat warnings and heat
advisories for Tuesday and Wednesday across a large portion of the
south-central Plains to the lower Ohio and Tennessee valleys. With
record-setting temperatures possible for portions of the Mid-Atlantic to
southern New England, heat advisories are also in effect for the
Philadelphia metro region.
Meanwhile, below-average temperatures will extend south and east across
the northern Plains and upper Midwest on Wednesday.
Across the Southwest, well-above average to record-breaking temperatures
are expected across the deserts of southern Nevada, California and
Arizona, with excessive heat warnings in effect across the region into
Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php