Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
563 ACUS03 KWNS 300727 SWODY3 SPC AC 300726 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CDT Thu May 30 2024 Valid 011200Z - 021200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE SATURDAY AFTERNOON AND EVENING ACROSS PARTS OF EASTERN COLORADO...WESTERN AND CENTRAL NEBRASKA AND WESTERN KANSAS... ...SUMMARY... Scattered strong storms, including a few supercells, may develop to the east of the Front Range Saturday afternoon, before evolving into organizing clusters while spreading into the adjacent Great Plains through Saturday evening. These may pose a risk for severe wind, hail and perhaps a couple of brief tornadoes. ...Synopsis... In the wake of amplified mid/upper troughing forecast to continue slowly shifting away from the Atlantic Seaboard, stronger westerlies across the northern tier of the U.S. may trend more zonal Saturday through Saturday night. As ridging across the subtropics remains suppressed, weak zonal flow appears likely to persist across the southern tier of the U.S., gradually developing into and across the southern Atlantic Seaboard. Beneath this regime, seasonably high moisture content air will likely remain confined to the lee of the southern Rockies, but gradually continue advecting eastward across and east of the lower Mississippi Valley, in the wake of a lead low-amplitude short wave forecast to approach the southern Appalachians. Downstream of troughing advancing inland of the Pacific coast within both streams, models indicate at least one initially subtle perturbation may undergo amplification, perhaps enhanced by convective development, as it progresses to the east of the Front Range Saturday afternoon and evening. It is possible that another wave may similarly impact the Pecos Valley/Texas Big Bend vicinity, but this potential appears more uncertain due to greater model differences. ...Front Range into adjacent Great Plains... It appears that large-scale mid/upper forcing for ascent will become conducive thunderstorm initiation off the higher terrain Saturday afternoon. This activity is expected to intensify as it propagates into slowly deepening lee surface troughing, where boundary-layer moistening may become sufficient to support CAPE on the order of 1000-2000 J/kg. Veering wind profiles with height beneath modest westerly mid-level flow probably will contribute to sufficient shear for a few supercells, initially, posing a risk for severe hail and perhaps a couple of brief tornadoes. It appears that this convection will gradually grow upscale in the presence of forcing aided by lower/mid-tropospheric warm advection, with evolving clusters posing increasing potential for strong to severe wind gusts deeper into the plains, before weakening by late Saturday evening. ...Lower Mississippi Valley into Southwest Texas... Potential storm coverage remains uncertain in the wake of the lead short wave perturbation progressing to the east of the lower Mississippi Valley. Mid-level heights may tend to rise during the day. However, mid-level inhibition might not be prohibitive to thunderstorm initiation, at least initially, particularly across parts of southeast Texas into the lower Mississippi Valley. Deep-layer mean wind fields and shear probably will remain modest to weak, but destabilization and approach of convective temperatures with insolation may support widely scattered to scattered storms posing at least some risk for severe wind and hail. ..Kerr.. 05/30/2024 $$