Transcript Slide 1
Storm Track Capabilities at CPC: Monitoring and Research Jon Gottschalck, Tim Eichler, Wayne Higgins, and Vern Kousky PRIDE Alaska Coastal Climatologies Wind/Wave Workshop Anchorage, Alaska August 2, 2005 Outline 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 Plans 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) ENSO CLIMATE MJO AO NAO PNA Blocking Storm Tracks Talk Focus WEATHER Storm Track Monitoring Storm Tracking Specifics Algorithm developed at CDC -- Serreze (1995) and Serreze et al. 1997 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 Deep cyclones just southwest of Alaska Slow moving storms off California coast in early February Frequent Alberta clippers in early March Red dot indicates active storm Total 7-day precipitation (mm) 2. Gulf of Alaska Block Avg 7-day anomalous 925 mb vector wind anomalies (m/s) and magnitude (m/s, shaded) Avg 7-day significant wave height (m) Red dot indicates active storm Total 7-day precipitation (mm) Forecast Products May 15: GFS Operational 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 Mean seasonal storm frequency AMJ JAS OND 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 Active source region east of Japan Demise region in the western Aleutian Islands High frequency of dissipation in the Gulf of Alaska Storm Track Composites -- ENSO 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 Mean seasonal frequency / difference Storm Track Time Series JFM OND 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?? Red dot indicates active storm Total 7-day precipitation (mm) 1. Active Pacific Jet Stream 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 -- # of closed circulations (6 hr data) in a given 10°x10° grid box February 5, 2005 – May 1, 2005 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 Cyclogenesis/Cyclolysis Climatology Mean seasonal frequency JFM AMJ JAS OND Cyclogenesis/Cyclolysis Composites -- ENSO Mean seasonal frequency Cyclogenesis in the central North Pacific and Gulf of Mexico Cyclolysis in the North Pacific Cyclolysis across the Aleutian Islands, western Alaska, and the Alaskan panhandle Storm Track Composites --AO Storm Track Frequency OND JFM Storm Track Minimum Pressure OND JFM