SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1226 AM CDT Sat May 27 2023 Valid 271200Z - 281200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHERN COLORADO NORTHWARD THROUGH THE BLACK HILLS AND EASTERN WYOMING AND INTO SOUTHEAST MONTANA... ...SUMMARY... Isolated to scattered severe thunderstorms appear possible across much of the High Plains this afternoon and evening. Large hail and severe gusts are the primary hazards. ...Synopsis... A blocking pattern in the mid to upper levels will continue over the Lower 48 states. Surface high pressure will be centered over the Great Lakes while lower pressure will reside over the Intermountain West and High Plains. Moist southerly low-level flow will maintain a moist fetch through the High Plains from south to north. Diurnally driven thunderstorms are again expected over the High Plains. ...CO northward into eastern MT/western Dakotas... A western U.S. large-scale mid-level trough will feature an enhanced belt of south-southwesterly flow moving from western CO into the western Dakotas during the period. A plume of steep 700-500 mb lapse rates will overlay a seasonably moist airmass (featuring 50s dewpoints) as the boundary layer heats/destabilizes during the day. Widely scattered to scattered thunderstorms are forecast to develop by early to mid afternoon along the western fringe of moisture near the CO Front Range and northward into east-central WY. Forecast soundings indicate potential for loosely organized small clusters and a few supercells during the afternoon and evening. Large hail and severe gusts are possible with the stronger storms. As this activity eventually moves into western ND and east of the Black Hills tonight, decreasing instability will likely limit storm intensity and the overall severe threat. ...Raton Mesa southward to the TX Big Bend... Residual shower/thunderstorm activity may be ongoing this morning over parts of west and northwest TX before dissipating by late this morning. Strong heating in wake of this activity farther west will result in moderate destabilization across eastern NM into southwest TX. Strongly veering flow with height will support some organization with the stronger updrafts. Large hail and severe gusts will be the primary threats. One or more clusters could evolve during the evening across eastern NM into parts of west/northwest TX. If this scenario of a thunderstorm cluster or two becomes more probable and uncertainty is lessened, a greater risk for severe gusts may occur near the NM/TX border/South Plains area. ...Carolinas... A surface low is forecast to advance northward towards the NC/SC coast through the period. Forecast soundings along the coast show generally northeasterly low-level flow for much of the day. This should tend to limit the inland advance of substantial low-level moisture, and keep appreciable severe chances offshore. ..Smith/Wendt.. 05/27/2023
