Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 423 PM EDT Mon Jun 28 2021 Valid 00Z Tue Jun 29 2021 - 00Z Thu Jul 01 2021 ...Record-shattering heat forecast across the Northwest with cooler temperatures finally entering areas west of the Cascades by Tuesday... ...Additional rounds of heavy rain and flash flooding likely over the Southern High Plains today... ...Flash flooding threat continues from the Midwest to the Southern Plains through Tuesday, including parts of southwest Louisiana and the Upper Texas Coast... ...Above average temperatures and oppressive heat found across the Northeast early this week, while well below average temperatures continue across much of the Southern Rockies/Plains... Additional oppressive heat is expected across the Pacific Northwest today, before the core of the unprecedented heat shifts into interior sections of the region on Tuesday and Wednesday. High temperatures are forecast to soar 30+ degrees above average throughout Washington and north-central Oregon to start the workweek, with temperatures peaking in the 100s and 110s. Numerous daily, monthly, and all-time temperature records are forecast on top of the records that went up in flames this weekend. To put it in perspective, Portland and Seattle broke their all-time high yesterday with high temperatures of 104 and 112 degrees, respectively. This level of heat is extremely dangerous and can be deadly if proper heat safety is not followed. Low temperatures are expected to remain very warm and in the mid-70s, which can make it even more difficult to stay cool. Excessive Heat Warnings have been issued throughout most of the Northwest, Northern Great Basin, as well as parts of western Nevada and interior California. Residents are urged to stay in air-conditioned buildings, avoid strenuous outdoor activities, drink plenty of water, and check on family members/neighbors. Cooler temperatures associated with a cold front and onshore winds are forecast to enter areas west of the Cascades by Tuesday, but extreme heat will remain and build farther inland across the Northern Great Basin this week. Additional high temperature records are a guarantee for interior sections of Washington and Oregon over the next few days, extending into most of Idaho and western Montana on Tuesday. For the central U.S., showers and thunderstorms will pose a threat of flash flooding once again today and linger through midweek. A stationary boundary bisecting the country from the Lower Great Lakes to West Texas will be the focus for thunderstorm activity and intense rainfall rates. The Southern High Plains in particular are forecast to have the greatest chances of significant flash flooding. A Moderate Risk (level 3/4) of Excessive Rainfall has been issued through Tuesday morning across southeast New Mexico and parts of West Texas, where widespread rainfall amounts of 2 to 5 inches are possible over previously saturated land. Farther east, slow-moving thunderstorms may also lead to flash flooding between central Oklahoma and northern Illinois. Much of this region has dealt with numerous instances of heavy rain and flooding over the last week; therefore, any additional downpours could lead to flash flooding. A Slight Risk (level 2/4) of excessive rainfall is in effect today from the Chicago Metro extending southwest through Oklahoma City to the Red River. Little change to the pattern is expected through tomorrow, and a Slight Risk of excessive rain is in effect on Tuesday over Southeast New Mexico, and Northern Oklahoma through Southeast Kansas with additional thunderstorm development forecast. Not to be outdone, tropical showers with efficient rainfall rates are also possible throughout the Upper Texas Coast and Southwest Louisiana today and Tuesday. Thunderstorms here will have the capability of producing 2 to locally 4 inches of rain in a short amount of time atop a flood sensitive area. An additional Slight Risk area extends along the coast, including the Houston Metro, until tomorrow morning. Meanwhile, newly named Tropical Storm Danny is just offshore the southern South Carolina coast, approximately 45 miles SSE of Charleston, per the National Hurricane Center. By this evening, Danny is forecast to move inland, producing tropical storm conditions as it makes landfall. Tropical Storm Warnings arc from the coastal South Carolina-Georgia border northward to the central South Carolina coast and slightly inland, including areas north/northwest of Charleston through late tonight/early tomorrow morning. Maximum sustained winds near 40 mph are currently estimated from Doppler RADAR and Air Force Reserve reconnaissance aircraft. In addition to the wind near the coast, some heavy rainfall is possible from coastal South Carolina and Georgia inland over East-Central Georgia and all but Northwest South Carolina, although widespread flood issues are not anticipated. Fortunately, Danny is forecast to quickly weaken to a depression by Tuesday morning as it treks northwest toward north Georgia. The northwest corner of the country isn't the only place dealing with oppressive heat this week. While not nearly as extreme, parts of New England and the Northeast are expected to experience hot and muggy weather through Wednesday as a Bermuda high pressure system ushers consistent southerly winds up the East Coast. High temperatures are forecast to reach the low-to-mid 90s from Virginia to Maine, with heat indices into the triple digits. Heat Advisories have been issued between Delaware and Maine, with a subset of cities including Philadelphia, Wilmington, and Trenton under an Excessive Heat warning from Tuesday to Wednesday. The opposite is true for the Southern Rockies and Southern Plains, where much below average temperatures are expected to remain through at least Wednesday. Cloud cover and showers are forecast to keep high temperatures in the 70s, which equates to 20-30 degrees below average. Asherman/Snell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php