823 FXUS01 KWBC 201929 PMDSPD Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 321 PM EDT Mon Apr 20 2026 Valid 00Z Tue Apr 21 2026 - 00Z Thu Apr 23 2026 ...Pacific system will bring precipitation to the West Coast the next couple of days, with heavy snow expected for the Sierra Nevada... ...A lingering frontal boundary will bring showers and thunderstorms to portions of Texas, with isolated flash flooding possible... ...Showers and thunderstorms forecast to recommence in the Northern and Central Plains late on Wednesday night/Thursday morning... A deep Pacific upper-level trough and associated surface frontal system will continue progressing inland along the West Coast over the next couple of days, bringing increasingly widespread precipitation as it continues eastward. Moderate to locally heavy showers and thunderstorms will move into portions of northern/central California this afternoon/evening before expanding in coverage into the Pacific Northwest, Great Basin, and into southern California Tuesday. The highest rain totals are expected to converge along the coastal ranges of northern/central California and upslope regions of the Sierra Nevada, where some isolated flooding could occur. Additionally, very heavy snow is forecast in the Sierra Nevada region, where totals could reach as high as 12-18 inches on Tuesday and Wednesday. The highest peaks of the mountainous areas could even see up to 2 feet of snow. Other higher elevation mountains throughout northern California as well as into the Great Basin and north into the Cascades could also see snow, though with more limited accumulations. The system will shift into the northern Rockies on Wednesday, bringing lower elevation rain and high elevation mountain snow, before continuing eastward through the CONUS. Showers and thunderstorms are expected to continue in southern Florida and parts of south Texas, as a quasi-stationary frontal boundary remains in place over the next several days. Isolated flash flooding will be possible for portions of Texas, with the greatest concentration of storms expected along the boundary, first through central Texas today and then further east towards the Upper Texas Gulf Coast on Tuesday. As such, a Marginal Risk (level 1/4) of excessive rainfall is expected for this area of Texas over the next three days, per the latest WPC Excessive Rainfall Outlook. Elsewhere, lingering wintry mix will taper off across portions of the Interior Northeast today, and an incoming frontal system will bring scattered showers and thunderstorms to the Great Lakes/Ohio Valley vicinity Tuesday. Later this week, the aforementioned deep upper-level trough will traverse its way through the west, and arrive into the western Plains by midweek. Concurrently, a dryline is expected to develop from southwest Texas up through much of eastern Colorado. An influx of moisture from the Gulf, and a strong southerly low-level jet will aid in producing thunderstorms along the cold front in the Northern Plains on Wednesday evening. This will also set the stage for a potentially active end to the week in the medium range for the Plains. 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 midweek. 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 today into the 70s and 80s by Wednesday. Meanwhile, to the east, lingering cooler air will continue today 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. Additionally, an Elevated Risk of fire weather is expected for parts of the southern Mid-Atlantic, Southeast, and parts of the central Plains today, and Florida and parts of the lower Mississippi Valley on Tuesday. Blanco-Alcala/Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php $$