523 FXUS01 KWBC 200725 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 324 AM EDT Mon Apr 20 2026 Valid 12Z Mon Apr 20 2026 - 12Z Wed Apr 22 2026 ...Pacific system will bring increasing precipitation chances to the West Coast the next couple of days with locally heavy lower elevation rain and heavy snow for the Sierra... ...A lingering frontal boundary will bring daily thunderstorm chances to portions of Texas with isolated flash flooding possible... ...Widespread well above average temperatures for the Interior West into the Plains while much of the eastern U.S. remains colder following a frontal passage this weekend... A deep Pacific upper-low and associated surface frontal system will begin to slowly progress inland along the West Coast over then next couple of days bringing increasingly widespread precipitation chances. Moderate to locally heavy showers and thunderstorms will first move into portions of northern/central California today (Monday) before expanding in coverage into the Pacific Northwest, Great Basin, and into southern California Tuesday. The highest rain totals are expected to focus along the coastal ranges of northern/central California and upslope regions of the Sierra, where some isolated flooding could occur Monday-Tuesday. In addition to the rainfall, very heavy snow is forecast in the Sierra peaking on Tuesday, and totals could reach as high as 1-2 feet. Other higher elevation mountains throughout northern California as well as into the Great Basin and north into the Cascades may also see some snow, though amounts should remain more limited. The storm system will shift into the northern Rockies Wednesday bringing lower elevation rain and high elevation mountain snow. Additional showers and thunderstorms are expected to focus along a quasi-stationary frontal boundary lingering through South Florida today as well as west into Texas through the next few days. Some isolated flash flooding will be possible for portions of Texas where the greatest concentration of storms focus along the boundary, first through central Texas today and then further east towards the Upper Texas Gulf Coast on Tuesday. Precipitation chances elsewhere around the country will be rather limited early this week. A lingering wintry mix will taper off across portions of the Interior Northeast today, and an incoming frontal system will bring some scattered shower and thunderstorm chances to the Great Lakes/Ohio Valley vicinity Tuesday. A strong upper-level ridge will bring a period of well above average temperatures from the Interior West into the northern/central Plains and then Midwest through mid-week. Forecast highs will be into the 70s and low 80s, with some mid- to upper-80s possible for locations in the northern/central Plains Tuesday-Wednesday. The incoming Pacific system will gradually bring in cooler weather from the west, first to the West Coast by Tuesday as highs fall into the 50s and 60s, and then into the Great Basin Wednesday as highs fall mainly into the 50s. The Desert Southwest will trend downwards from the 90s Monday into the 70s and 80s by Wednesday. Meanwhile, to the east, lingering cooler air will be in place Monday following a frontal passage. The coldest temperatures will be across the Midwest and Northeast with highs mainly in the 40s and 50s. Morning lows dropping to the low 30s Tuesday morning have prompted Freeze Warnings across portions of the Ohio Valley into the Mid-Atlantic. Much of Texas will also be below average with cloud cover and rainy conditions in place as the front lingers in the region, with highs mainly in the 60s on Monday. Average to above average conditions will return to most Tuesday-Wednesday as the airmass modifies following the frontal passage, with 60s and 70s for more northern locations and 80s along the southern tier. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$