CW3E AR Update: 15-17 December 2016 Outlook

CW3E AR Update: 15-17 December 2016 Outlook

December 15, 2016

Click here for a pdf of this information.

  • AR conditions could last up to 24 more hours over northern CA resulting in as much as 1–3 more inches of precipitation
  • Flood warnings have been issued by the NWS at locations in Oregon and northern California
  • Visit weather.gov for point specific watches, advisories and warnings

Update on AR Impacting California

  • The AR has begun to move southward as precipitation continues to fall over northern California
  • 48-h precipitation accumulations range from 1–10 inches over portions of northern CA


 

 

 

 

Summary provided by C. Hecht, and F.M. Ralph; 1 PM PT Wed 15 Dec. 2016

CW3E AR Update: 14-17 December 2016 Outlook

CW3E AR Update: 14-17 December 2016 Outlook

December 14, 2016

Click here for a pdf of this information.

  • NWS precipitation forecasts for the rest of the event continue to predict higher precipitation amounts of ~10 inches in 3 days over the higher elevations of the Sierra Nevada Mts. with other locations in northern CA receiving an additional 2-10 inches
  • CNRFC river forecasts are now predicting several river gages to rise above flood stage

Update on AR Impacting California

  • Precipitation has begun falling in portions of northern CA and southern Oregon where 24-h precipitation accumulations range from 1 to 4.9 in.
  • AR conditions are expected to continue over northern California for the next 48-hrs before moving southward


 

 

 

 

Summary provided by C. Hecht, and F.M. Ralph; 1 PM PT Wed 14 Dec. 2016

CW3E AR Update: 13-17 December 2016 Outlook

CW3E AR Update: 13-17 December 2016 Outlook

December 13, 2016

Click here for a pdf of this information.

  • Current NWS precipitation forecasts predict higher precipitation amounts of over 10 inches in 3 days over the higher elevations of the Sierra Nevada Mts. with other locations in northern CA receiving 2-10 inches
  • Recent heavy precipitation has primed soil conditions and river flows to raise concern for flooding in some locations in northern California, as seen in NWS river forecasts

Landfalling AR to impact California

  • A moderate-strength AR is expected to make landfall in north/central California tonight, and could reach “strong” AR level
  • The AR propagates southward later in the week bringing AR conditions to portions of southern California

Click IVT or IWV image to see loop of 0-90 hour GFS forecast (Valid 1200 UTC 13 Dec – 0600 17 Dec)


 

 

 

 

Summary provided by C. Hecht, and F.M. Ralph; 12 PM PT Tue 13 Dec. 2016

October 2016 Summary

October 2016 Summary

November 23, 2016

CW3E provides a summary of October 2016, one of the wettest Octobers on record for the Western United States. Several Atmospheric Rivers (ARs) made landfall along the U.S. West Coast and led to record setting precipitation production. For specific details on AR events refer to the CW3E AR Summaries, found on the CW3E News page.

Click here for a pdf file of this information.



 

 

 

 

 

 

 

 

 

Summary provided by C. Hecht, B. Kawzenuk, and F.M. Ralph

Water Year 2016 Summary

Water Year 2016 Summary

October 15, 2016

CW3E provides a summary of the top ten precipitation events based on the Northern Sierra 8-Station index during Water Year 2016 (Oct. 1 2015 – Sep. 30 2016). The top ten events occurred over a total of 27 days, and resulted in 30.09 inches of precipiation representing 51.89% of total water year precipitaiton and 60.2% of normal water year precipitation. All events were associated with an Atmospheric River (AR), with 6 considered strong ARs (IVT >750 kg m-1) s-1. For event specific reports refer to the CW3E News Page. For up to date AR forecasts and analysis visit the CW3E AR Portal.

Click here for a pdf file of this information.


 

 

 

 

 

Summary provided by B. Kawzenuk, and F.M. Ralph

CW3E AR Update: 4-9 November 2016 Outlook

CW3E AR Update: 4-9 November 2016 Post Event Summary

November 4, 2016

Two consecutive ARs are expected to make landfall over the Northwest U.S. and Southwest British Columbia. Current forecasts show both ARs with moderate strength, although there is high uncertainty in the forecast of the second AR. Despite high values of integrated vapor transport (IVT) forecasted precipitation values of the Northwest U.S. are modest due to the southwesterly orientation of the ARs. However, this orientation is favorable for precipitation production over Vancouver Island, where 5-day precipitation forecasts are >12 inches. For up to date AR forecasts visit the CW3E AR Portal.

Click here for a pdf file of this information.


 

 

Summary provided by C. Hecht, B. Kawzenuk, and F.M. Ralph; 3 PM PT Fri 05 Nov. 2016

CW3E AR Update: Post-Event Summary: 14-17 October 2016

CW3E AR Update: 14-17 October 2016 Post-Event Summary

October 20, 2016

CW3E gives a post-event storm summary about two Atmospheric Rivers that made landfall over the Pacific Northwest during 14-17 October 2016. This event was an R-Cat 3 event and produced over 15 inches of 72-hour precipitation.

Click here for a pdf file of this information.

NCEP GFS Analysis – Valid: 0000 UTC 12 Oct 2016 – 0600 UTC 17 Oct 2016

 

NEXRAD Radar: 0000 UTC 14-17 Oct 2016

  • Radar imagery shows widespread precipitation over the Pacific Northwest during 14-17 Oct 2016
  • Severe convection on 14 Oct produced multiple tornadoes in OR and high winds across the region
  • Throughout the period the PNW was impacted by several alternating periods of stratiform and convective precipiation