Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 400 PM EDT Sat Mar 30 2024 Valid 00Z Sun Mar 31 2024 - 00Z Tue Apr 02 2024 ...Unsettled weather continues across the West Sunday with some locally heavy rainfall and isolated flood risk for Southern California and Arizona... ...Risk for severe weather and flash flooding from the Middle Mississippi Valley southwestward into the Southern Plains on Monday... ...Showers and storms with some severe weather and flash flooding threat for portions of the Midwest/Ohio Valley Sunday into Monday... Unsettled weather will continue across the West as a deep upper-trough and accompanying surface frontal system push inland across the region. Widespread showers and storms will continue this evening in Southern California but should decrease in coverage/intensity as the cold front pushes eastward, reducing the influx of moisture. A Slight Risk of Excessive Rainfall (level 2/4) remains in effect for the LA Basin/eastern Transverse Ranges south through the Peninsular Ranges through Sunday morning where the additional rainfall may lead to some instances of flooding given the wet antecedent conditions from the prior days' rainfall. Some more isolated instances may also continue into the day Sunday before the rain fully tapers off. Additional locally heavy rainfall with an isolated flood risk will stretch into the Lower Colorado River Valley through Sunday morning, and into portions of southern Arizona Sunday. Otherwise, lower elevation rain showers/thunderstorms and higher elevation mountain snow are expected more broadly across the Great Basin, Southwest, and Rockies Sunday. Locally heavy snow is forecast for some of the regional mountain ranges, particularly from the Sierra eastward through the Great Basin/Four Corners region into the central Rockies, with some Winter Storm Warnings/Winter Weather Advisories in place. Some snow may mix in at lower elevations in the Great Basin and into the Rockies as temperatures remain cooler following a cold front passage, though any accumulations should remain light. Precipiation chances should come down through the day Monday as the frontal system pushes eastward into the Plains. As the upper-trough shifts east, lee cyclogenesis will help to strengthen/consolidate an area of low pressure over the Central Plains along a wavy, quasi-stationary boundary extending eastward through the Middle-Mississippi Valley and into the Mid-Atlantic. This boundary will become the focus for areas of widespread showers and thunderstorms over the next couple of days. The Central/Southern Plains will remain mostly dry Sunday, with precipitation limited to a wintry mix to the north of the boundary over portions of the Northern Plains in the presence of moist, upslope flow. Some light to moderate snow accumulations are expected, particularly in vicinity of the Black Hills. Then, on Monday, the focus shifts southeastward to the frontal boundary through the Middle Mississippi Valley southwestward along a dry line and approaching cold front through the Southern Plains. Increasing moisture/buoyancy as well as strengthening deep and low-level shear will lead to the threat of numerous thunderstorms with the potential for severe weather. The Storm Prediction Center has outlined an Enhanced Risk (level 3/5) from central Missouri southwestward into eastern Oklahoma where an increasing potential for very large hail, damaging winds, and tornadoes exists. A broader Slight Risk extends southward into north Texas. In addition, the expectation for repeated storms with increasing coverage as flow runs parallel to the approaching cold front has prompted an overlapping Slight Risk of Excessive Rainfall from central Missouri southwestward into northeastern Oklahoma. The threat for scattered instances of flash flooding will likely be greatest from Monday evening into Monday night, just beyond the current forecast period. Very gusty winds and dry conditions west of the dryline/cold front over the Southern High Plains have also prompted a Critical Risk of Fire Weather (level 2/3) from the Storm Prediction Center for Sunday, likely to continue into Monday. Further east, increasing storms are also expected Sunday along the boundary from the Middle Mississippi Valley eastward through the Midwest/Ohio Valley. Some storms may be severe, with a Slight Risk of severe weather from central Illinois eastward into central Indiana mainly for the threat of some large hail. Storms will increase in coverage and intensity on Monday following an additional day of southerly moist Gulf flow. A broader Slight Risk of severe weather is in place from central/southern Illinois into central/southern Indiana for some additional instances of large hail as well as damaging winds, with a potentially greater threat into Monday evening as storms from the west over the Plains grow upscale into an organized line and move eastward into the region. Some threat for flash flooding also exists, though the extent to which remains a bit more uncertain and will likely be dictated by boundary placement and storm coverage/intensity, harder to predict at this time frame. Forecast temperatures overall will tend to be warmer/above average for eastern/southern portions of the country, south of the noted frontal system, and cooler/below average to the north and west. Highs will be well above average in particular from the Central/Southern Plains eastward through the Middle Mississippi/Ohio Valleys and into the southern Mid-Atlantic, with highs generally in the upper 70s and 80s, and some 90s forecast into Texas. Temperatures will be rather chilly in the Northern Plains, mainly in the 30s and low 40s, and much cooler than average in Southern California through the Desert Southwest, with mostly 60s expected. Putnam Graphics available at https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php