TZUTC: 0000   
   MSGID: 167328.weather@1:2320/105 2d99ade4   
   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   
   FOUS30 KWBC 042008   
   QPFERD   
      
   Excessive Rainfall Discussion   
   NWS Weather Prediction Center College Park MD   
   308 PM EST Thu Dec 4 2025   
      
   Day 1   
   Valid 16Z Thu Dec 04 2025 - 12Z Fri Dec 05 2025   
      
   ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR THE CENTRAL   
   GULF COAST...   
      
   ...16Z Outlook Update...   
   The ongoing forecast philosophy is generally on track. Latest   
   CAMs/12Z guidance and observations depict redevelopment of deep   
   convection over far northwestern open waters of the Gulf that will   
   stream northeastward into southern Louisiana through much of the   
   day today. Some of these showers/storms will occur over/near areas   
   that have experienced 1.5-4 inches of rain so far today, with   
   isolated instances of excessive runoff remaining possible. 1.75+ PW   
   values remain in place along the Louisiana coast today and upstream   
   mid-level shortwave troughs will migrate through the region from   
   Texas - both supporting locally heavy rainfall through the evening   
   hours. Given the latest observations and model guidance, the   
   Marginal Risk area has been maintained for this update with minor   
   spatial edits.   
      
   Cook   
      
   ...Previous Discussion...   
      
   Upglide/warm-advective elevated convective activity is ongoing this   
   morning across portions of the central Gulf Coast with localized   
   hourly totals topping out near an inch or so (per MRMS estimates).   
   Right entrance ascent to 150-170 kt jet centered over the Ohio   
   Valley will keep isentropic moisture flux across the surface front   
   that will remain oriented along and south of the coast. A weak   
   mid-level shortwave will slide from west to east along the   
   southern periphery of the jet streak maintaining 20-25kt of west-   
   southwesterly 850mb flow which given ~1.75" PWs and the potential   
   for lingering marginal instability (MU CAPE up to 1000 J/kg now,   
   but forecast to decrease below 500 J/kg later this morning) may   
   maintain elevated convective development into midday. Internal   
   training of back-building convective elements will present the   
   greatest potential for higher rainfall totals across the Bayous of   
   south-central LA.   
      
   Hi-Res CAMs are in general good agreement with the heaviest   
   rainfall along and south of I-10 (where 3" exceedance probs from   
   both the 00z HREF and experimental REFS are contained). Little   
   change in the inherited MRGL risk, which will likely be pulled   
   around midday as convective activity wraps up.   
      
   Churchill/Gallina   
      
      
   Day 2   
   Valid 12Z Fri Dec 05 2025 - 12Z Sat Dec 06 2025   
      
   The probability of rainfall exceeding flash flood guidance is less   
   than 5 percent.   
      
   Hurley   
      
      
   Day 3   
   Valid 12Z Sat Dec 06 2025 - 12Z Sun Dec 07 2025   
      
   The probability of rainfall exceeding flash flood guidance is less   
   than 5 percent.   
      
   The low-end Marginal Risk that was in effect across parts of the   
   Southeast (North FL and Panhandle, southern AL-GA, southern SC) has   
   been removed. Model QPFs from the 12Z have trended lower, while   
   also still showing latitudinal spread with the axis of max totals.   
   All of the rainfall is post-frontal, so any available instability   
   would be elevated, and even then there's not much per the guidance   
   (<500 J/Kg). Probability Match Mean (PMM) of 12Z global guidance is   
   generally 0.75-1.00" in 24hrs, which is actually lower than the 17Z   
   NBM.=20   
      
   Given the latest areal-average deterministic QPF (again ~0.75-1.00   
   in the 24hr period from 12Z Sat to 12Z sun 4hrs), along with the=20   
   fact that much of the Southeast is between a D2-D4 drought with 3=20   
   hourly FFGs between 2.5-3", probabilities of even getting close to=20   
   those values are quite low -- certainly sufficiently low to remove   
   the Marginal.   
      
   Hurley   
      
   Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=   
   v/qpf/94epoints.txt__;!!DZ3fjg!4i0wLbdFp56sPQD_9Qd3NCNKp2geXzKufvZygLsAPYDS=   
   2vLjGZZQLBbzMIqG22xZM0zbnsahvuZEo_GubevuBVJdiTY$=20   
   Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=   
   v/qpf/98epoints.txt__;!!DZ3fjg!4i0wLbdFp56sPQD_9Qd3NCNKp2geXzKufvZygLsAPYDS=   
   2vLjGZZQLBbzMIqG22xZM0zbnsahvuZEo_Gubevu68aJhfI$=20   
   Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=   
   v/qpf/99epoints.txt__;!!DZ3fjg!4i0wLbdFp56sPQD_9Qd3NCNKp2geXzKufvZygLsAPYDS=   
   2vLjGZZQLBbzMIqG22xZM0zbnsahvuZEo_GubevunbdKN5s$=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