CW3E Atmospheric River Update

Size: px

Start display at page:

Download "CW3E Atmospheric River Update"

Kelley Simpson
5 years ago
Views:

1 CW3E Atmospheric River Update Update on ARs Currently Impacting and Forecast to Impact West Coast As much as 6.5 inches of precipitation has fallen over the high elevations of CA over the previous 48 hours Several rivers and streams are currently experiencing flooding in the San Francisco Bay Area The second AR is forecast to make landfall at ~4 AM on Wednesday 8 February An additional 5 10 inches of precipitation could fall over already wet soils, raising concern for additional flooding

3 6.5 inches of precipitation has fallen over the high elevations of the northern Sierra Nevada and the Coastal Mountains over the last 48-hrs Lower elevations in the

2 3 6.5 inches of precipitation has fallen over the high elevations of the northern Sierra Nevada and the Coastal Mountains over the last 48-hrs Lower elevations in the northern Central Valley have received 1 2 inches of precipitation For official NOAA-NWS observed precipitation see cnrfc.noaa.gov/rfc_guidance.php Ending 7 AM PST 7 Feb

gov At ~10 am PST, the Napa River at Saint Helena, CA rose to ~19 feet, the second highest flood on record The potential impacts associated with

3 There are currently 5 river gauges that have risen above flood stage and an additional 27 above monitor stage Current River Stage Heights (as of 12 PM PST) For official information on point specific flood warnings and watches visit weather.gov At ~10 am PST, the Napa River at Saint Helena, CA rose to ~19 feet, the second highest flood on record The potential impacts associated with a stage height of 19 feet are: Major flooding throughout the upper Napa Valley with most roads inundated making travel extremely difficult. Moderate to severe damage to all towns along the reach

Sonoma County Several Rivers and streams

4 Sonoma County Several Rivers and streams are currently experiencing flooding in Sonoma County and the Bay Area Sonoma County by Bob Redell Martinez by Elyce Kirchner Photos from NBC Bay Area. Visit yarea.com/news/l ocal/second- Storm-Wreaks- Havoc-Across-Bay- Area html for more information Niles Canyon by Matt Ulrich

5 The next AR is currently forecast to make landfall at ~4 AM on 8 February 2017 with maximum IVT ~1000 and IWV ~34 mm

6 AR conditions (IVT >250 m 1 s 1 ) could potentially last until 10 pm PST on Thursday 9 February over Central CA before the AR propagates southward bringing AR conditions to Southern CA on 10 February

7 Moderate AR conditions (IVT >500 m 1 s 1 ) could last ~24-hrs in association with the second AR 10 PM PST 8 February to 10 PM PST 9 February

IVT magnitude will gradually decrease in association with the first AR until this afternoon Forecasts of IVT magnitude have increased for the second AR since yesterdays update Maximum possible IVT ~

8 IVT magnitude will gradually decrease in association with the first AR until this afternoon Forecasts of IVT magnitude have increased for the second AR since yesterdays update Maximum possible IVT ~ 950 kg m 1 s 1 Mean IVT ~ 900 kg m 1 s 1 Minimum possible IVT ~ 750 kg m 1 s 1 Uncertainty ~ +/ 15% IVT will increase back above weak AR conditions with the landfall of the second AR around midnight PST on Wednesday 8 February Duration of AR conditions Weak: ~36 hours +/ 12 h Moderate: ~24 hours +/ 15 h Strong: ~12 hours +/ 6 h

Over the next 3 days The lower elevations of the Central Valley, and Sonoma, Napa, and Marin Counties (areas currently

9 An additional 5 10 inches of precipitation is forecast to fall over the high elevations of the Sierras, Trinity Alps, and the Coastal, Cascade, and Olympic Mts. Over the next 3 days The lower elevations of the Central Valley, and Sonoma, Napa, and Marin Counties (areas currently experiencing flooding) are forecast to receive an additional inches For Official NOAA-NWS and CNRFC Precipitation Forecasts see wpc.ncep.noaa.gov/qpf/qpf2.shtml Or cnrfc.noaa.gov/rfc_guidance.php

AR Outlook: 7 February 2017 There are 22 total river gauges that are currently at or forecast to rise above flood stage in Northern California As of 12 PM PST There are an additional 34 gauges that

php With the precipitation from both ARs, the Middle Fork of the Feather River at Portola, CA is forecast to rise to 10.5 feet on Wednesday afternoon before rising again to 10.

10 AR Outlook: 7 February 2017 There are 22 total river gauges that are currently at or forecast to rise above flood stage in Northern California As of 12 PM PST There are an additional 34 gauges that are currently at or expected to rise above monitor stage For official NOAA-NWS CNRFC Streamflow Forecasts see cnrfc.noaa.gov/rfc_guid ance.php With the precipitation from both ARs, the Middle Fork of the Feather River at Portola, CA is forecast to rise to 10.5 feet on Wednesday afternoon before rising again to 10.8 feet on Friday Afternoon The potential impacts associated with a stage height of 10.5 feet are: Major (near record) flooding of lowlands, roads, railroads, homes, businesses and structures along river from Beckwourth to Sloat California, including Portola.with significant damage. Flow are forecasted to reach approximately 7400 cfs. The flood of record was on January and reached 7640 cfs.

CW3E Atmospheric River Update

CW3E Atmospheric River Update Update on AR Currently Impacting CA, OR, and WA Precipitation continues to fall over portions of Northern California, Washington, and Oregon 6 10 inches of precipitation has