Flash Flood Guidance
Issued by NWS
Issued by NWS
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969 AWUS01 KWNH 050048 FFGMPD MOZ000-ARZ000-OKZ000-KSZ000-050545- Mesoscale Precipitation Discussion 0558 NWS Weather Prediction Center College Park MD 847 PM EDT Thu Jul 04 2024 Areas affected...Northeast & Eastern OK...Southwest MO...Northwest AR... Concerning...Heavy rainfall...Flash flooding possible Valid 050045Z - 050545Z SUMMARY...Weakly organized convection within very rich moisture field may produce locally intense rainfall that may produce a few incidents of flash flooding. DISCUSSION...Current regional RADAR mosaic depicts scattered thunderstorms across eastern OK that have developed in very weak low level flow environment. While environment has been very unstable with 3500-4000 J/kg of CAPE, inflow at cloud base has been limited to less than 10kts and 7H wind field has shown divergence across the area to limit organization in the near term; with new development sprouting on older outflow. Still, moisture rich environment with over 2-2.25" total PWats result in quick 2" in about an hour, before collapsing. This alone is not going to exceed the very high FFG values, but with soil saturation below 15% across much of eastern OK, this hard ground may not allow much infiltration given these intense sub-hourly rates and may result in very high run off. Given the broader up/downdrafts, these may cross multiple smaller watersheds (or urban centers) resulting in lower-end localized flash flooding conditions. As night falls, surface analysis and RAP trends show the cold front is starting to press southward across SE KS given stronger height-falls as the mid-level trough starts digging and the jet streak starts to expand right entrance region divergence downstream across SW MO/NW AR. While slightly drier, there remains a shallow moisture pool post front, so with strengthening 15-25kts of west to northwest flow counter to the 5-10kts of southwest/south flow, moisture convergence will increased in proximity the boundary and overall convective coverage will increase from scattered to numerous. Divergence/outflow and DPVA may aid overall organization of convection with some repeating elements crossing over to SW MO/NW AR after nightfall. Similar 2-2.5"/hr rates will result in spots of 2-3"; this may be most concerning for the lowered FFG across S MO where there has been recent rainfall, but again; sub-hourly intensity across harder ground conditions further south in AR may also result in possible spotty incidents of flash flooding. Gallina ...Please see www.wpc.ncep.noaa.gov for graphic product... ATTN...WFO...LZK...OUN...SGF...TSA... ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...NWC... LAT...LON 37979268 37659167 36899128 35909162 35379242 34959405 34789548 35219656 36199669 36719618 36989505 37499407