AI6YR Ben
@ai6yr@m.ai6yr.org  ·  activity timestamp 11 hours ago
Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 229 PM EST Mon Dec 22 2025 Day 3 Valid 12Z Wed Dec 24 2025 - 12Z Thu Dec 25 2025 ...THERE IS A HIGH RISK FOR EXCESSIVE RAINFALL ACROSS SOUTHERN CALIFORNIA... 2100 UTC UPDATE: The primary change to the previous day 3 Excessive Rainfall Outlook was to add a high risk area along the west to east Transverse Range region of Southern California after collaboration with WFO LOX. Anomalous 850-700 mb moisture flux...5+ standard deviations above the mean...will impact Southern CA late day 2 into day 3 ahead of the amplifying mid to upper level trof off the CA coast. The heavy rainfall totals for Southern CA will likely occur over an 18 hour period, with widespread 4-7 inch totals, with isolated max amounts of 9"+. Expect a well defined south to north precip band in this anomalous moisture flux axis with hourly rainfall rates of .50-1.5"+ likely. The potential for high hourly rainfall totals will accentuate runoff over soil that is relatively dry and or over recent burn scar areas. This will pose a significant threat of flash flooding, landslides, rock falls and mud slides. The greater than normal travel during the Christmas Holiday will likely expose a potentially larger number of people to these lift threatening hazards and was taken into consideration with the upgrade to high risk.
Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 229 PM EST Mon Dec 22 2025 Day 3 Valid 12Z Wed Dec 24 2025 - 12Z Thu Dec 25 2025 ...THERE IS A HIGH RISK FOR EXCESSIVE RAINFALL ACROSS SOUTHERN CALIFORNIA... 2100 UTC UPDATE: The primary change to the previous day 3 Excessive Rainfall Outlook was to add a high risk area along the west to east Transverse Range region of Southern California after collaboration with WFO LOX. Anomalous 850-700 mb moisture flux...5+ standard deviations above the mean...will impact Southern CA late day 2 into day 3 ahead of the amplifying mid to upper level trof off the CA coast. The heavy rainfall totals for Southern CA will likely occur over an 18 hour period, with widespread 4-7 inch totals, with isolated max amounts of 9"+. Expect a well defined south to north precip band in this anomalous moisture flux axis with hourly rainfall rates of .50-1.5"+ likely. The potential for high hourly rainfall totals will accentuate runoff over soil that is relatively dry and or over recent burn scar areas. This will pose a significant threat of flash flooding, landslides, rock falls and mud slides. The greater than normal travel during the Christmas Holiday will likely expose a potentially larger number of people to these lift threatening hazards and was taken into consideration with the upgrade to high risk.
Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 229 PM EST Mon Dec 22 2025 Day 3 Valid 12Z Wed Dec 24 2025 - 12Z Thu Dec 25 2025 ...THERE IS A HIGH RISK FOR EXCESSIVE RAINFALL ACROSS SOUTHERN CALIFORNIA... 2100 UTC UPDATE: The primary change to the previous day 3 Excessive Rainfall Outlook was to add a high risk area along the west to east Transverse Range region of Southern California after collaboration with WFO LOX. Anomalous 850-700 mb moisture flux...5+ standard deviations above the mean...will impact Southern CA late day 2 into day 3 ahead of the amplifying mid to upper level trof off the CA coast. The heavy rainfall totals for Southern CA will likely occur over an 18 hour period, with widespread 4-7 inch totals, with isolated max amounts of 9"+. Expect a well defined south to north precip band in this anomalous moisture flux axis with hourly rainfall rates of .50-1.5"+ likely. The potential for high hourly rainfall totals will accentuate runoff over soil that is relatively dry and or over recent burn scar areas. This will pose a significant threat of flash flooding, landslides, rock falls and mud slides. The greater than normal travel during the Christmas Holiday will likely expose a potentially larger number of people to these lift threatening hazards and was taken into consideration with the upgrade to high risk.
AI6YR Ben
@ai6yr@m.ai6yr.org  ·  activity timestamp 8 hours ago
Impacts & Suggested Actions Ample holiday travel impacts expected Tue Night through Thu: Plan for road & airport delays. High risk of rock/mudslides Heavy flows in creeks & rivers: Stay away from rivers & creeks, especially campers. Small chance of main stem river flooding Widespread strong winds Tue-Wed with Downed trees & power outages. Stay off the ocean. Park cars away from tall trees. Rain Details: (Tue-Sat Night) Timing: May be off by 12 hours, heaviest during Tuesday night into Wednesday, Wednesday night into Thursday Most Likely Scenario North of Point Conception Peak rates 0.4-1.0 inch/hour: Totals: 2-4 inches, foothillstmountains 4-8 inches Most Likely Scenario South of Point Conception: Peak rates 0.6-1.25 inch/hour,Totals: 4-8 inches, foothills+mountains 6-12+ inches 15-30 percent chance of Thunderstorms Tuesday night-Thursday (Christmas Day) Snow levels likely 7,000+ ft through Christmas Morning, then lowering to 5,500-7,000 feet by late Christmas Day into weekend
Impacts & Suggested Actions Ample holiday travel impacts expected Tue Night through Thu: Plan for road & airport delays. High risk of rock/mudslides Heavy flows in creeks & rivers: Stay away from rivers & creeks, especially campers. Small chance of main stem river flooding Widespread strong winds Tue-Wed with Downed trees & power outages. Stay off the ocean. Park cars away from tall trees. Rain Details: (Tue-Sat Night) Timing: May be off by 12 hours, heaviest during Tuesday night into Wednesday, Wednesday night into Thursday Most Likely Scenario North of Point Conception Peak rates 0.4-1.0 inch/hour: Totals: 2-4 inches, foothillstmountains 4-8 inches Most Likely Scenario South of Point Conception: Peak rates 0.6-1.25 inch/hour,Totals: 4-8 inches, foothills+mountains 6-12+ inches 15-30 percent chance of Thunderstorms Tuesday night-Thursday (Christmas Day) Snow levels likely 7,000+ ft through Christmas Morning, then lowering to 5,500-7,000 feet by late Christmas Day into weekend
Impacts & Suggested Actions Ample holiday travel impacts expected Tue Night through Thu: Plan for road & airport delays. High risk of rock/mudslides Heavy flows in creeks & rivers: Stay away from rivers & creeks, especially campers. Small chance of main stem river flooding Widespread strong winds Tue-Wed with Downed trees & power outages. Stay off the ocean. Park cars away from tall trees. Rain Details: (Tue-Sat Night) Timing: May be off by 12 hours, heaviest during Tuesday night into Wednesday, Wednesday night into Thursday Most Likely Scenario North of Point Conception Peak rates 0.4-1.0 inch/hour: Totals: 2-4 inches, foothillstmountains 4-8 inches Most Likely Scenario South of Point Conception: Peak rates 0.6-1.25 inch/hour,Totals: 4-8 inches, foothills+mountains 6-12+ inches 15-30 percent chance of Thunderstorms Tuesday night-Thursday (Christmas Day) Snow levels likely 7,000+ ft through Christmas Morning, then lowering to 5,500-7,000 feet by late Christmas Day into weekend
AI6YR Ben
@ai6yr@m.ai6yr.org  ·  activity timestamp 8 hours ago
Impacts & Suggested Actions Ample holiday travel impacts expected Tue Night through Thu: Plan for road & airport delays. High risk of rock/mudslides Heavy flows in creeks & rivers: Stay away from rivers & creeks, especially campers. Small chance of main stem river flooding Widespread strong winds Tue-Wed with Downed trees & power outages. Stay off the ocean. Park cars away from tall trees. Rain Details: (Tue-Sat Night) Timing: May be off by 12 hours, heaviest during Tuesday night into Wednesday, Wednesday night into Thursday Most Likely Scenario North of Point Conception Peak rates 0.4-1.0 inch/hour: Totals: 2-4 inches, foothillstmountains 4-8 inches Most Likely Scenario South of Point Conception: Peak rates 0.6-1.25 inch/hour,Totals: 4-8 inches, foothills+mountains 6-12+ inches 15-30 percent chance of Thunderstorms Tuesday night-Thursday (Christmas Day) Snow levels likely 7,000+ ft through Christmas Morning, then lowering to 5,500-7,000 feet by late Christmas Day into weekend
Impacts & Suggested Actions Ample holiday travel impacts expected Tue Night through Thu: Plan for road & airport delays. High risk of rock/mudslides Heavy flows in creeks & rivers: Stay away from rivers & creeks, especially campers. Small chance of main stem river flooding Widespread strong winds Tue-Wed with Downed trees & power outages. Stay off the ocean. Park cars away from tall trees. Rain Details: (Tue-Sat Night) Timing: May be off by 12 hours, heaviest during Tuesday night into Wednesday, Wednesday night into Thursday Most Likely Scenario North of Point Conception Peak rates 0.4-1.0 inch/hour: Totals: 2-4 inches, foothillstmountains 4-8 inches Most Likely Scenario South of Point Conception: Peak rates 0.6-1.25 inch/hour,Totals: 4-8 inches, foothills+mountains 6-12+ inches 15-30 percent chance of Thunderstorms Tuesday night-Thursday (Christmas Day) Snow levels likely 7,000+ ft through Christmas Morning, then lowering to 5,500-7,000 feet by late Christmas Day into weekend
Impacts & Suggested Actions Ample holiday travel impacts expected Tue Night through Thu: Plan for road & airport delays. High risk of rock/mudslides Heavy flows in creeks & rivers: Stay away from rivers & creeks, especially campers. Small chance of main stem river flooding Widespread strong winds Tue-Wed with Downed trees & power outages. Stay off the ocean. Park cars away from tall trees. Rain Details: (Tue-Sat Night) Timing: May be off by 12 hours, heaviest during Tuesday night into Wednesday, Wednesday night into Thursday Most Likely Scenario North of Point Conception Peak rates 0.4-1.0 inch/hour: Totals: 2-4 inches, foothillstmountains 4-8 inches Most Likely Scenario South of Point Conception: Peak rates 0.6-1.25 inch/hour,Totals: 4-8 inches, foothills+mountains 6-12+ inches 15-30 percent chance of Thunderstorms Tuesday night-Thursday (Christmas Day) Snow levels likely 7,000+ ft through Christmas Morning, then lowering to 5,500-7,000 feet by late Christmas Day into weekend
AI6YR Ben
@ai6yr@m.ai6yr.org  ·  activity timestamp 11 hours ago
Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 229 PM EST Mon Dec 22 2025 Day 3 Valid 12Z Wed Dec 24 2025 - 12Z Thu Dec 25 2025 ...THERE IS A HIGH RISK FOR EXCESSIVE RAINFALL ACROSS SOUTHERN CALIFORNIA... 2100 UTC UPDATE: The primary change to the previous day 3 Excessive Rainfall Outlook was to add a high risk area along the west to east Transverse Range region of Southern California after collaboration with WFO LOX. Anomalous 850-700 mb moisture flux...5+ standard deviations above the mean...will impact Southern CA late day 2 into day 3 ahead of the amplifying mid to upper level trof off the CA coast. The heavy rainfall totals for Southern CA will likely occur over an 18 hour period, with widespread 4-7 inch totals, with isolated max amounts of 9"+. Expect a well defined south to north precip band in this anomalous moisture flux axis with hourly rainfall rates of .50-1.5"+ likely. The potential for high hourly rainfall totals will accentuate runoff over soil that is relatively dry and or over recent burn scar areas. This will pose a significant threat of flash flooding, landslides, rock falls and mud slides. The greater than normal travel during the Christmas Holiday will likely expose a potentially larger number of people to these lift threatening hazards and was taken into consideration with the upgrade to high risk.
Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 229 PM EST Mon Dec 22 2025 Day 3 Valid 12Z Wed Dec 24 2025 - 12Z Thu Dec 25 2025 ...THERE IS A HIGH RISK FOR EXCESSIVE RAINFALL ACROSS SOUTHERN CALIFORNIA... 2100 UTC UPDATE: The primary change to the previous day 3 Excessive Rainfall Outlook was to add a high risk area along the west to east Transverse Range region of Southern California after collaboration with WFO LOX. Anomalous 850-700 mb moisture flux...5+ standard deviations above the mean...will impact Southern CA late day 2 into day 3 ahead of the amplifying mid to upper level trof off the CA coast. The heavy rainfall totals for Southern CA will likely occur over an 18 hour period, with widespread 4-7 inch totals, with isolated max amounts of 9"+. Expect a well defined south to north precip band in this anomalous moisture flux axis with hourly rainfall rates of .50-1.5"+ likely. The potential for high hourly rainfall totals will accentuate runoff over soil that is relatively dry and or over recent burn scar areas. This will pose a significant threat of flash flooding, landslides, rock falls and mud slides. The greater than normal travel during the Christmas Holiday will likely expose a potentially larger number of people to these lift threatening hazards and was taken into consideration with the upgrade to high risk.
Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 229 PM EST Mon Dec 22 2025 Day 3 Valid 12Z Wed Dec 24 2025 - 12Z Thu Dec 25 2025 ...THERE IS A HIGH RISK FOR EXCESSIVE RAINFALL ACROSS SOUTHERN CALIFORNIA... 2100 UTC UPDATE: The primary change to the previous day 3 Excessive Rainfall Outlook was to add a high risk area along the west to east Transverse Range region of Southern California after collaboration with WFO LOX. Anomalous 850-700 mb moisture flux...5+ standard deviations above the mean...will impact Southern CA late day 2 into day 3 ahead of the amplifying mid to upper level trof off the CA coast. The heavy rainfall totals for Southern CA will likely occur over an 18 hour period, with widespread 4-7 inch totals, with isolated max amounts of 9"+. Expect a well defined south to north precip band in this anomalous moisture flux axis with hourly rainfall rates of .50-1.5"+ likely. The potential for high hourly rainfall totals will accentuate runoff over soil that is relatively dry and or over recent burn scar areas. This will pose a significant threat of flash flooding, landslides, rock falls and mud slides. The greater than normal travel during the Christmas Holiday will likely expose a potentially larger number of people to these lift threatening hazards and was taken into consideration with the upgrade to high risk.
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