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   TID: SBBSecho 3.28-Linux master/123f2d28a Jul 12 2025 GCC 12.2.0   
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   FOUS30 KWBC 140042   
   QPFERD   
      
   Excessive Rainfall Discussion   
   NWS Weather Prediction Center College Park MD   
   742 PM EST Sat Dec 13 2025   
      
   Day 1   
   Valid 01Z Sun Dec 14 2025 - 12Z Sun Dec 14 2025   
      
   ...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF   
   SOUTHEASTERN FLORIDA...   
      
   01Z Update...   
   HREF probs have come down with the 18Z run, but still show some=20   
   indication that showers and storms developing farther north along=20   
   the southeast coast of Florida may produce localized heavy amounts   
   along the urban corridor. Therefore, maintained the small Marginal   
   Risk.   
      
   Pereira   
      
   Previous discussion...   
   A weak mid-level wave over the eastern Gulf will aid in increasing   
   mid-level flow/ascent across the Florida Peninsula and adjacent   
   Gulf Stream during the overnight hours. Meanwhile, low-level   
   moisture will increase across coastal areas as a weak surface   
   boundary/inverted trough becomes established just inland across the   
   Peninsula. PW values should increase into the 1.6-1.8 inch range   
   amid 500+ J/kg SBCAPE. Meanwhile, point forecast soundings depict   
   favorable kinematic profiles for relatively slow-moving cells that   
   could impact urban areas of southeast Florida along the I-95   
   corridor. Local 1+ inch/hr rates are possible. Urban flash flooding   
   is possible in the 03-12Z timeframe this evening/tonight.   
      
   Cook   
      
   Day 2   
   Valid 12Z Sun Dec 14 2025 - 12Z Mon Dec 15 2025   
      
   ..THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF   
   WESTERN WASHINGTON STATE LATE SUNDAY NIGHT/EARLY MONDAY MORNING...   
      
   2100 UTC Update -- No changes made to the Marginal Risk outlook   
   based on the new (12Z) guidance. 12Z HREF window runs through the   
   entire D2 period, and of note is the uptick in 0.50"/hr   
   probabilities after 06Z -- peaking over 80% across the Olympic   
   Ranges toward 12Z Mon, and over 40% across portions of the Cascades   
   in WA.   
      
   Hurley   
      
   Previous discussion...   
      
   Maintained the Marginal Risk area over parts of the Olympic and   
   northern Cascade Ranges in Washington as the next push of moisture   
   approaches late Sunday night into the early morning hours of   
   Monday. The models have shown some run to run differences with QPF   
   but no real clear trend. One consistent signal is that the   
   orientation of the moisture plume remained more southwest-northeast   
   than the event that just ended a couple of days ago. That still   
   points to the idea that rainfall may not increase in coverage or   
   intensity until late in the Day 2 period. Based on the expected IVT   
   plume increasing to over 600 at about the time that the flow   
   reaches the coast and begins to take on more of an on- shore   
   component...am inclined to follow the ensemble idea of 0.75 inches   
   to locally 1.5 inches of precipitation focused in the terrain. The   
   area is sensitive given the nearly week-long excessive rainfall   
   event...so any additional rainfall is expected to bring renewed   
   hydrologic concerns. Given a fairly tight window of opportunity for   
   rainfall during the outlook period...and at least some questions   
   about timing of the onset....still think a Marginal Risk is   
   sufficient for now although later shifts can adjust if needed.   
      
   Bann   
      
   Day 3   
   Valid 12Z Mon Dec 15 2025 - 12Z Tue Dec 16 2025   
      
   ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF   
   WASHINGTON AND OREGON...   
      
   2100 UTC Update -- Only minor (cosmetic) changes made to the   
   previous D3 outlook, some of which was to pull the eastern edges of   
   the Slight ever so slightly westward in WA based on the latest   
   snowfall forecast (lowering snow levels).   
      
   Hurley   
      
   Previous discussion...   
      
   Areal coverage of rainfall expands and rain rates increase on   
   Monday as a well defined atmospheric river continues to direct   
   abundant moisture into the Washington coastal ranges and Cascades   
   that gradually makes its way southward into Oregon. Given   
   antecedent conditions from the excessive rainfall event from   
   earlier in the week plus whatever falls on Day 2...the concern is   
   for renewed flooding potential in addition to worsening on-going   
   flooding especially in the terrain with potential for additional   
   landslides or mudslides. Saw little reason to modify the Slight   
   risk area that propagated into the Day 3 period from yesterdays Day   
   4 outlook especially given the magnitude of the IVT and   
   precipitable water values forecast by the global models. The focus   
   of the heavy rainfall should gradually shift southward into an area   
   that did not receive as much rainfall from the previous   
   atmospheric river. Opted to extend a Marginal risk area along the   
   coast as far south as northwestern California more in deference to   
   uncertainty of timing as to the rainfall amounts.   
      
   Bann   
      
      
   Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=   
   v/qpf/94epoints.txt__;!!DZ3fjg!7djc-qCKjvyN-vNjM1lH-JQP92RPyYeelgW1crOzG_Ch=   
   8W9W4QN7D6AobEeil4jOtWCDyUPUs8ffgJDgLzeajuTmtZw$=20   
   Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=   
   v/qpf/98epoints.txt__;!!DZ3fjg!7djc-qCKjvyN-vNjM1lH-JQP92RPyYeelgW1crOzG_Ch=   
   8W9W4QN7D6AobEeil4jOtWCDyUPUs8ffgJDgLzeaypXRJGY$=20   
   Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=   
   v/qpf/99epoints.txt__;!!DZ3fjg!7djc-qCKjvyN-vNjM1lH-JQP92RPyYeelgW1crOzG_Ch=   
   8W9W4QN7D6AobEeil4jOtWCDyUPUs8ffgJDgLzea4ceNwSo$=20   
      
   =3D =3D =3D   
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