Alaska Coastal Climatologies Wind/Wave PRIDE Alaska Coastal Climatologies Wind/Wave Workshop Anchorage, Alaska August 2, 2005 Storm Track Capabilities at CPC: Monitoring and Research Jon Gottschalck, Tim Eichler, Wayne Higgins, and Vern Kousky

1. Overview of Climate/Weather Monitoring 2. Storm Track Monitoring -- Algorithm, data, and other specifics -- Storm track monitoring web page components and utility 3. Preliminary Research Work -- Storm Track Climatology -- Interannual Variability -- ENSO composites 4. Upcoming PlansOutline

A Broader View – Linking Climate and Weather at CPC -- Coordinated effort to monitor, assess and predict climate phenomena and their linkage to weather events -- CPC monitoring web pages [ENSO, MJO, Teleconnection Indices (PNA, AO, NAO), blocking, storm tracks] -- Most are highly relevant to Alaska weather (storms  wind/wave events) ENSOMJOAOBlockingStorm Tracks CLIMATE WEATHER PNANAO Talk Focus

Storm Track Monitoring

Storm Tracking Specifics  Algorithm developed at CDC -- Serreze (1995) and Serreze et al  Identifies SLP minima with a threshold of 1 mb (adjustable)  Storms are tracked by analyzing the position of systems between time steps and applying a maximum distance threshold between candidate pairings (800 km)  Maximum distance moved north, south, or west restrictions applied  GDAS 6-hourly, 2.5° x 2.5° spatial resolution for realtime monitoring  Data is converted to an equal area projection for tracking purposes

Example Storm Track Map Storm Tracks from February 14, 2005 – March 15, 2005 Slow moving storms off California coast in early February Frequent Alberta clippers in early March Deep cyclones just southwest of Alaska

2. Gulf of Alaska Block Total 7-day precipitation (mm) Red dot indicates active storm Avg 7-day anomalous 925 mb vector wind anomalies (m/s) and magnitude (m/s, shaded) Avg 7-day significant wave height (m)

Forecast Products May 15: GFS Operational Red dot indicates active storm Total 7-day precipitation (mm) Avg 7-day anomalous 925 mb vector wind anomalies (m/s) and magnitude (m/s, shaded) Avg 7-day significant wave height (m)

Preliminary Research Work

Storm Track Climatology JFM AMJ JAS OND Mean seasonal storm frequency

Interannual Variability – Storm Tracks Lower frequency and weaker cyclones High frequency and deep cyclones extend east into the North Pacific Frequent and deep cyclones in the Aleutian Island region

Interannual Variability – Cyclogenesis/Cyclolysis Demise region in the western Aleutian Islands High frequency of dissipation in the Gulf of Alaska Active source region east of Japan

Storm Track Composites -- ENSO Mean seasonal frequency / difference Strong El Nino Mod/Weak El Nino Neutral Mod/Weak La Nina Strong La Nina Greater frequency across the Aleutian Islands during La Nina Lower frequency along coastal Alaska during El Nino

Storm Track Time Series JFMOND

Upcoming Plans Monitoring: 1. Include CFS operational forecasts (although a week behind) 2. Verification section for both GFS / CFS operational forecasts

Upcoming Plans (cont.) Research: 1. Incorporate ideas/develop path using feedback from workshop 2. Assessment of interannual variability of storm characteristics (frequency, intensity, source/demise regions) in Alaska sphere 3. Evaluation of CFS daily hindcast data 4. Develop storm track climatology from NA Regional Reanalysis 5. Develop plan for Alaska seasonal storm outlook

Questions / Comments??

1. Active Pacific Jet Stream Total 7-day precipitation (mm) Red dot indicates active storm Avg 7-day anomalous 925 mb vector wind anomalies (m/s) and magnitude (m/s, shaded) Avg 7-day significant wave height (m)

Storm Days Southern California storminess in early to mid February Split flow in the eastern Rockies/western Plains from late February to mid-March Alberta clippers and southern Plains cyclones -- # of closed circulations (6 hr data) in a given 10°x10 ° grid box February 5, 2005 – May 1, 2005

Cyclogenesis/Cyclolysis Climatology JFM AMJ JAS OND Mean seasonal frequency

Cyclogenesis/Cyclolysis Composites -- ENSO Cyclogenesis in the central North Pacific and Gulf of Mexico Mean seasonal frequency Cyclolysis in the North Pacific Cyclolysis across the Aleutian Islands, western Alaska, and the Alaskan panhandle

Storm Track Composites --AO

Storm Track Frequency JFMOND

Storm Track Minimum Pressure ONDJFM