PRIDE Alaska Coastal Climatologies Wind/WaveAlaska Coastal Climatologies Wind/Wave WorkshopAnchorage, Alaska

August 2, 2005

Storm Track Capabilities at CPC:Storm Track Capabilities at CPC:Monitoring and ResearchMonitoring 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 Plans

OutlineOutline

A Broader View – Linking Climate and Weather at CPCA 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 MJO AO Blocking Storm Tracks

CLIMATE WEATHER

PNANAO

Talk Focus

Storm Track MonitoringStorm Track Monitoring

Storm Tracking SpecificsStorm 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 MapExample 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 Block2. 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 ProductsForecast Products

May 15May 15: GFS Operational: 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 WorkPreliminary Research Work

Storm Track ClimatologyStorm Track Climatology

JFM

AMJ

JAS

OND

Mean seasonal storm frequency

Interannual Variability – Storm TracksInterannual 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/CyclolysisInterannual 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 -- ENSOStorm 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 SeriesStorm Track Time SeriesJFM OND

Upcoming PlansUpcoming Plans

Monitoring:

1. Include CFS operational forecasts (although a week behind)

2. Verification section for both GFS / CFS operational forecasts

Upcoming Plans (cont.)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 Stream1. 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 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 ClimatologyCyclogenesis/Cyclolysis Climatology

JFM

AMJ

JAS

OND

Mean seasonal frequency

Cyclogenesis/Cyclolysis Composites -- ENSOCyclogenesis/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 --AOStorm Track Composites --AO

Storm Track FrequencyStorm Track Frequency

JFMOND

Storm Track Minimum PressureStorm Track Minimum Pressure

OND JFM