Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 251 PM EDT Mon Sep 30 2019 Valid 00Z Tue Oct 01 2019 - 00Z Thu Oct 03 2019 ...Widespread heavy rain and flash flooding likely from Southern Rockies to the Great Lakes region... ...Much below average temperatures across the Northwest into the Northern High Plains, and much above average temperatures east of the Rockies/Northern Plains... Snow has mostly diminished across the Intermountain West and High Plains region today as the storm system pushed further toward the Upper Mississippi Valley. The trailing front from this low pressure system will drop south and east through the Central Plains and will act as a focus for widespread showers and thunderstorms that will span from the Southern Rockies, the Southern and Central Plains, across the Midwest/Upper Midwest, Great Lakes and into portions of the Ohio Valley and Northeast. This event will be notable in that a large portion of the country will receive several inches of rain and elevated risks of flash flooding. The airmass will be extra juicy as tropical moisture streams northward from Tropical Storm Narda and combines with the deep layer of pooling moisture from the Gulf of Mexico moisture. Showers and thunderstorms will develop east of the Southern Rockies into the Middle Mississippi Valley along the frontal boundary. These storms will be very efficient rain makers. Also, the motion of the storms are expected to be slow which will greatly increase the possibility of ponding, rapid runoff and/or flash flooding over a very large area. Given the duration will likely occur over the course of a couple of days, streams and rivers will likely rise in response. WPC has a Moderate Risk for excessive rainfall in effect. For additional details, please refer to the Excessive Rainfall Outlooks. A large temperature range is expected across the lower 48 into Wednesday as an upper-level trough remains over the West and upper-level ridge anchored over the Southeast. Underneath the trough, daytime highs could be 20 to 30+ degrees below average across much of the Northwest with several daily record low maximum temperature records possible into Tuesday, especially across the Northern Great Basin/Rockies and California. Meanwhile east of the Rockies, temperatures will be much above average. The core of the heat will be from the Southeast/Central Gulf Coast States to the Ohio Valley where widespread daytime highs in the mid to upper 80s near 90 (north) and mid to upper 90s (south) could approach or exceed record values. For the East, this stretch of record warmth will continue through much of the week. Additionally, warm, dry, and gusty weather across Colorado will continue the critical fire weather conditions through Monday where red flag warnings are currently in effect. Campbell Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php