Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
347 PM EDT Tue Jun 19 2018
Valid 00Z Wed Jun 20 2018 - 00Z Fri Jun 22 2018
...Flash flooding and strong thunderstorms expected from the Central
Plains eastward across the Ohio Valley and into the Mid-Atlantic region...
...Heavy showers and flash flooding continues along and near the Texas
...Hot weather continues across the Carolinas...and gradually builds again
over the Southwestern U.S...
A slow-moving frontal system extending from the Central Plains eastward
across the Middle Mississippi Valley, Ohio Valley, and Mid-Atlantic states
will remain a focus for multiple rounds of showers and thunderstorms
through Thursday. With a very warm and humid air mass aligned with the
front, some of the storms could be severe, as well as produce localized
excessive rainfall and flash flooding. During Tuesday night and
Wednesday, an upper level disturbance moving out of the Rockies will help
bring the best chance of widespread rainfall to the Plains and Middle
Mississippi Valley. As this disturbance pushes eastward on Thursday, the
high Plains will begin to dry out, but widespread showers/thunderstorms
will continue over the Mississippi Valley and extend eastward along the
front through the Ohio Valley and central Appalachians.
South of this front, deep tropical moisture and a trough of low pressure
extending from a low in southern Texas will continue the threat for
widespread heavy rainfall across eastern and southeastern Texas through
Wednesday. Flash flood watches are posted across this region given the
high moisture values in place and heavy rains that fell on Monday. During
Thursday, the most organized activity of showers and thunderstorms will
tend to be drawn north and eastward into the lower Mississippi Valley
ahead of a slow-moving cold front, though a weak upper level disturbance
will maintain the threat heavy, slow-moving storms and localized flooding
across eastern Texas.
Farther east over the Carolinas, the heat wave will continue, with highs
ranging into the mid-upper 90s through Thursday. As a result, heat
advisories remain in effect for eastern sections of North and South
Carolina. Hot weather will begin to abate over southern Virginia and
sections of the middle Mississippi Valley as clouds and the chance for
rain increases in association with the aforementioned slow-moving frontal
Across the western U.S., dry and very warm conditions will persist through
Wednesday over the Pacific Northwest; however, an upper level trough
moving in from the Pacific will bring clouds and cooler conditions by
Thursday. Over the Southwest, a building upper ridge will bring
increasingly hot conditions to the region through the end of the week.
Excessive heat warnings are posted from sections of southeastern
California, southern Nevada and southern Arizona.
Over the northern tier of states, persistent clouds and showers over the
northern Intermountain region/Rockies and high Plains will briefly abate
on Wednesday as high pressure builds in. By Thursday, however, the upper
trough that brings cooler temperatures to the Pacific Northwest will move
inland and potentially trigger another round of rainfall for the region.
Mostly dry conditions are expected from the upper Mississippi Valley
eastward across the Northeast. A weakening cold front may bring scattered
showers or thundershowers to New England Wednesday afternoon, but rainfall
amounts should be light.
Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php