Flash Flood Guidance
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Issued by NWS
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909 AWUS01 KWNH 011205 FFGMPD OKZ000-011630- Mesoscale Precipitation Discussion 0203 NWS Weather Prediction Center College Park MD 804 AM EDT Wed May 01 2024 Areas affected...Central to Eastern Oklahoma... Concerning...Heavy rainfall...Flash flooding possible Valid 011205Z - 011630Z SUMMARY...Increasing warm-advection T`storms capable of 1.5-3" over sensitive soils may pose increased runoff and spotty flash flooding incident(s) this morning. DISCUSSION...GOES-E 10.3um IR shows a well defined MCV from the decaying MCS over far southeastern OK into western AR. The MCS has laid out a well defined outflow boundary from the MCV along/just north of the Red River before angling back northwest from Love county toward Custer county, OK. VWP suite depicts a stronger than forecast lingering LLJ with FDR suggesting 50+ kts of south-southwesterly flow with slowly veering flow in the wake of the MCS across southern and eastern OK. CIRA LPW also notes an enhanced pocket of moisture in the 850-700mb layer nearing the Red River into SW OK which also matches up with MUCAPE axis of 2000 J/kg along the western edge of that outflow. As such, a gradient of unstable mid-level air with solid isentropic ascent has sparked an NW to SE axis of thunderstorms. Moisture is modest in the 1.25-1.4" range and flux is also supporting of up to 1.5"/hr rates with occasional localized convergence values that may supports spots up to 2". With a veered steering profile, initial cells are lifting northeastward, but propagation vectors and 500-300mb flow from the west suggests some eastward/southeastward motions may start to unfold over the next few hours along/near the outflow boundary. Given continued upwind ascent (per RADAR suite), redevelopment along the outflow as the boundary slowly drifts west, may allow for repeating/back-building even prior to the convergence in deeper-steering flow. This may allow for 1 to 2 hours of duration and allow for spots of 1.5-3" totals. The bad news, the placement/track of the southern axis across south-central OK will cross sensitive, recently flooded areas...where AHPS depicts a broad area of 250%+ of 7day rainfall anomalies from Cotton to S Osage county and southeastward, with spots of 500%+ from Love to Seminole/Hughes county. So currently, not ideally aligned, but still concerning enough to suggest spots/localized incidents of flash flooding are possible through this morning. Further north near the KS/OK border...Another similar axis has developed along an exposed area of return southeasterly flow not generally obstructed by ongoing convection to the south and southwest. The surface front is also sagged across this area while the main LLJ core lifts the warm front further west. So a bit of enhanced convergence across areas hit hard last night, bleeding into Osage county...may see a similar if slightly muted situation as described above with a spot of flash flooding still possible as well before diurnal convective minima/stabilization occurs later this morning. Gallina ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...OUN...TSA... ATTN...RFC...ABRFC...NWC... LAT...LON 36979725 36879643 36219563 35449513 34869507 34119534 33889613 33879644 34029699 34509783 35219842 35579833 36119761 36349758 36719748