Flash Flood Guidance
Issued by NWS
Issued by NWS
299 AWUS01 KWNH 092238 FFGMPD COZ000-NMZ000-100401- Mesoscale Precipitation Discussion 0414 NWS Weather Prediction Center College Park MD 637 PM EDT Sun Jun 09 2024 Areas affected...central Colorado into northern New Mexico Concerning...Heavy rainfall...Flash flooding possible Valid 092237Z - 100401Z Summary...Showers and thunderstorms will become increasingly widespread through the evening and move slowly across the Front Range and Sangre de Cristos into the High Plains of CO/NM. Rainfall rates of 1-2"/hr are expected, which could result in 1-2" of rain with isolated higher amounts. Flash flooding is possible. Discussion...The regional radar mosaic the past hour or two has shown a rapid expansion of higher reflectivity comprising more widespread showers and thunderstorms. The focus of this activity has been generally across the higher terrain of the Front Range, Sangre de Cristos, and Jemez Mountains where SBCAPE has climbed above 2000 J/kg according to the SPC RAP analysis. This instability is combining with PWs of 0.7 to 0.9 inches, around the 90th percentile for the date, to produce an environment easily supporting this intensifying convection. Low-level moist advection on post-frontal easterly flow is resupplying moisture and upsloping into the terrain to further support the environment for heavy rainfall producing convection. As the afternoon progresses, the high-res CAMs, although currently underplaying the coverage of convection, suggest thunderstorms will expand even further and intensify, with the HREF indicating the probabilities for 1"/hr rain rates reaching above 50% by this evening. These storms will continue to form in a pulse environment characterized by minimal bulk shear, so lifespans should be generally short except where immediately adjacent development occurs on terrain features, outflow boundaries, or storm collisions. Additionally, mean cloud layer winds are extremely weak at just around 5 kts, so storm motions will remain slow and chaotic. These slow storm motions will support rainfall that could exceed (40-50% chance) 2 inches in a few locations. Where these intense rates linger, where multiple rounds occur, or if a storm moves across a sensitive terrain feature, burn scar, or urban area, instances of flash flooding could result. Eventually, convection is expected to congeal and move east off the terrain this evening. Depending on how this evolves into tonight, additional MPDs may be needed to address that threat as well. Weiss ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...ABQ...BOU...PUB... ATTN...RFC...ABRFC...MBRFC...WGRFC...NWC... LAT...LON 39500496 39220431 38130378 37070377 35780442 35350501 35260616 35630677 36100658 36600626 37240605 37720604 39170628