Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 403 AM EDT Sun Jul 17 2022 Valid 12Z Sun Jul 17 2022 - 12Z Tue Jul 19 2022 ...Dangerous heat to continue across portions the central and western United States... ...Scattered flash flooding possible across much of the Ohio Valley today, with isolated heavy rainfall forecast across the Southwest through the beginning of next week... ...Elevated fire weather conditions expected for portions of the southern Cascades and Great Basin today... A strong upper-level high will continue to support above-normal to record-breaking heat across much of the western and central U.S. today. More than 27 million residents are under an Excessive Heat Warning or Heat Advisory. These areas include parts of interior Southern California, the Southwest, the Great Basin, and a large section of the southern Plains into the lower Mississippi Valley. With the heat building across the northern Plains, heat advisories are in effect across eastern Montana as well. Warm overnight temperatures followed by triple-digit heat in many locations will increase the potential for heat-related illnesses, particularly for those working or participating in outdoor activities. Slightly cooler temperatures are expected across the Southwest beginning Monday, but temperatures will remain much above normal across the southern Plains through the period. The well above normal temperatures in the northern Plains are expected to shift east, with daytime temperatures forecast to reach record-breaking highs across portions of western South Dakota and Nebraska on Monday. By Tuesday, a cold front will bring relief to the northern High Plains, with a significant drop in temperatures expected across eastern Montana into the western Dakotas. Ahead of the front however temperatures will remain well above-normal across the remainder of the northern and central Plains into the Upper Midwest. In addition to cooler temperatures, the front will be bring an increasing threat for scattered severe thunderstorms from northeast Montana eastward through North Dakota into northwest Minnesota on Monday into Monday night. Storms that develop across this area will have potential to produce damaging winds and large hail. Across the Southwest, monsoonal moisture will support afternoon shower and thunderstorm development each day from parts of the Southwest into the Great Basin and the central to southern Rockies. While these storms may bring beneficial rains to some, there is also the threat for isolated flash flooding, especially across vulnerable wildfire burn scar areas. Dry and windy conditions farther to the northwest have prompted red flag warnings for portions of southern Oregon, northern California, and northwestern Nevada. Conditions across the area combined with critically dry vegetation will greatly increase the spread potential of any new or existing fires. Farther east, a slow-moving frontal boundary continues to extend from the Mid Atlantic states back into the southern Plains. Showers and storms will continue to focus along the front today, especially from the Ozark region northeastward through the Ohio Valley. Some of these storms may become strong to severe, with damaging wind and hail possible. A very moist airmass ahead of the front will support the threat for heavy rains as well, which may lead to localized instances of flash flooding across the Ohio Valley today. Pereira Graphics are available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php