Subj : MESO: Nws Weather Prediction Center College Park Md To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat May 06 2023 04:09:13 AWUS01 KWNH 060409 FFGMPD TXZ000-060700- Mesoscale Precipitation Discussion 0227 NWS Weather Prediction Center College Park MD 1206 AM EDT Sat May 06 2023 Areas affected...Central Texas Concerning...Heavy rainfall...Flash flooding possible Valid 060400Z - 060700Z Summary...Localized rainfall rates of 1-2"/hr may allow for additional isolated instances of flash flooding over the next several hours. Discussion...Deep convective activity continues to percolate late this evening across portions of central Texas, taking advantage of a highly moist and unstable air mass (located between a dry line to the west and a warm front to the east). The mesoscale environment is characterized by MU CAPE of 2000-4000 J/kg, precipitable water values of 1.3-1.6 inches (between the 90th percentile and max moving average, per FWD sounding climatology), and effective bulk shear of 30-40 kts. This environment has been supportive of realized hourly totals of 1-2"/hr over the past several hours (with MRMS hourly rates estimated to be as high as 1-3"/hr), despite convection being fairly progressive thus far (with storm motions generally between 15-30 kts towards the ESE). Storms organization continues to be semi-discrete, despite regional proliferation seemingly -trying- to lead to the development of a mesoscale convective system (MCS). Further organization seems unlikely, given that the strongest cores have become outflow dominate with cold pools surging to the south against the weak (~10 kt) southerly surface flow. The main concern going forward is continued backbuilding of convection along and north of the southwest trailing flank of this outflow, as new updrafts have already favored this backbuilding/repeating orientation (as the mean 850-300 mb flow is directed towards the east-northeast). In addition, as the mesoscale environment continues to be modified by growing cold pools, the already slow bunkers right-moving vectors (around 10-15 kts) may allow for even slower motion (5-10 kts) as there has been a notable uptick in the low-level jet to 25-35 kts over the past 2 hours (per SPC mesoscale analysis). Elevated convection may continue for several more hours (taking advantage of still high MU CAPE) before the low-level jet eventually veers and dry air entrainment from the west marks an end to new convective development. In the meantime, additional isolated instances of flash flooding will be possible due to the continuation of 1-2"/hr rainfall rates near locations that have already received 2-6 inches of rainfall over the past 3-4 hours (given short-term observational trends, as CAMs have continually handled the convective evolution rather poorly). Churchill ....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!= DZ3fjg!9FAd0kHWVo17BUvXqNEUe-3g-1kmiFVzcEgVm8bXwYX9IQJ0VsNZ_EvvjmXK7Ot3O7SP= j4puSlvruBq7cibETQhIz5g$ for graphic product... ATTN...WFO...EWX...FWD...HGX...SJT... ATTN...RFC...WGRFC...NWC... LAT...LON 31789731 31719636 31289558 31049564 30499633=20 30129722 30099830 30509909 31409873 31679816=20 =20=20=20=20=20=20=20=20=20=20=20=20 =3D =3D =3D To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.14-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .