TZUTC: 0000   
   MSGID: 167478.weather@1:2320/105 2da054e9   
   PID: Synchronet 3.21a-Linux master/123f2d28a Jul 12 2025 GCC 12.2.0   
   TID: SBBSecho 3.28-Linux master/123f2d28a Jul 12 2025 GCC 12.2.0   
   BBSID: CAPCITY2   
   CHRS: ASCII 1   
   FORMAT: flowed   
   AWUS01 KWNH 092112   
   FFGMPD   
   ORZ000-WAZ000-100910-   
      
   Mesoscale Precipitation Discussion 1259   
   NWS Weather Prediction Center College Park MD   
   411 PM EST Tue Dec 09 2025   
      
   Areas affected...Northern Oregon and Western Washington   
      
   Concerning...Heavy rainfall...Flash flooding possible   
      
   Valid 092110Z - 100910Z   
      
   Summary...The ongoing atmospheric river event over the Pacific   
   Northwest will continue into tonight over portions of western   
   Oregon and Washington. The axis of heaviest rainfall is expected   
   to shift back north into Washington and also increase in   
   intensity, which will bring an increasing flood and landslide risk   
   to these areas.   
      
   Discussion...The expectation is that the atmospheric river   
   impacting northern OR will shift northward back into western WA   
   this evening. After a temporary drop in Integrated Water Vapor   
   Transport (IVT) today, values are forecast to increase again   
   towards 03z resulting in an uptick in rainfall coverage and   
   intensity into the overnight hours. With no forecast instability,   
   rainfall rates will be driven mostly by the magnitude of moisture   
   transport into the terrain. This will put a cap on the upper bound   
   of rainfall rates, although this will be compensated by IVT values   
   above the climatological 99th percentile and layered precipitable   
   water (PW) generally above the 95th percentile at all atmospheric   
   levels. This deep moisture and strong moisture transport will   
   support hourly rainfall in the 0.25"-0.40" range, potentially   
   approaching 0.50" in the highest mountain peaks. These rates   
   should increase in coverage after 03z (per the 12z HREF   
   probabilities), moving from northern OR into western WA overnight.   
   Additional rainfall through 09z Wednesday is generally expected to   
   be in the 1-3" range.   
      
   Under typical conditions, rainfall rates and totals of this   
   magnitude would not pose a significant hazard to this region.   
   However, the past 24 hours have already brought 4-10" of rain to   
   these locations, leading to saturated ground and elevated streams   
   and rivers. Although parts of WA saw a brief lull today allowing   
   for some recovery, hydrologic conditions remain sensitive.   
   Consequently, when heavier rain returns this evening into tonight,   
   additional flood impacts are expected.   
      
   The primary impacts are expected to be flooding of rivers and   
   streams, other low-lying flood-prone areas, and poor drainage and   
   urban areas. Given the saturated ground, the risk of landslides   
   and debris flows in areas of steep terrain will also increase   
   tonight as rainfall intensity ramps up.   
      
   Chenard   
      
   ...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=   
   DZ3fjg!43p-OkfUop706I6cKLYBBIwzA6nB0hPZtCxkYgIrTsd-VTMoHaWWkfw9qP6uMmlQkjOt=   
   HZdFGfUJBx9ZZGkLPPdfEFs$  for graphic product...   
      
   ATTN...WFO...OTX...PDT...PQR...SEW...   
      
   ATTN...RFC...PTR...NWC...   
      
   LAT...LON   47942123 47642074 46792112 46432130 45912145=20   
               45412151 45322145 44952164 44572184 44412215=20   
               44522255 44712277 45042250 45422224 45882270=20   
               45822308 45252331 44842354 44972399 45782413=20   
               46532407 47232417 47682412 47842384 47782333=20   
               47392322 47042294 46852251 47122208 47482197=20   
               47762182=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 3.28-Linux   
    * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105)   
   SEEN-BY: 1/19 100 16/0 19/10 37 104/119 105/81 106/201 114/10 120/302   
   SEEN-BY: 123/130 128/187 129/14 142/104 153/757 7715 154/10 30 50   
   SEEN-BY: 154/110 700 201/0 203/0 218/700 840 220/10 20 30 90 221/1   
   SEEN-BY: 221/6 360 226/18 30 44 50 227/114 229/110 134 206 300 307   
   SEEN-BY: 229/317 400 426 428 470 664 700 705 240/5832 266/512 280/5003   
   SEEN-BY: 291/111 301/1 320/119 219 319 2119 322/757 762 326/101 335/364   
   SEEN-BY: 341/66 342/200 396/45 423/81 460/58 633/280 712/848 902/26   
   SEEN-BY: 2320/0 105 304 3634/12 5020/400 5075/35   
   PATH: 2320/105 154/10 221/6 1 320/219 229/426