A Synoptic Overview of the Severe Bering Sea Storm of 2004 Are Severe Alaskan Coastal Storms Increas

1
A Synoptic Overview of the Severe Bering Sea
Storm of 2004Are Severe Alaskan Coastal Storms
Increasing in Frequency?

• Caroline J. Larsen
• Cooperative Institute for Arctic Research and
  the
• National Weather Service WFO Fairbanks, Alaska
• North Carolina State University
• Dr. John Walsh
• gt Add material from the Pacific ET transition
  article

2
Introduction/Objectives

• Introduction Severe storms along the Alaskan
  coast cause major flooding and beach erosion.
  Some villages, such as Shishmaref, are facing
  relocation because of this erosion.
• Objectives -Climatology of Alaskan coast storms
• Are they increasing in frequency
• -Investigate the Bering Sea storm of 2004
• Caused over 10 feet of storm surge in Nome
• Conduct a track analysis of the storm
• Investigate the storms dynamics

Photos courtesy of Mr. John Lingaas, NWS WFO
Fairbanks, AK
3
Background

• Alaska regions
• South
• Anchorage, Kenai Peninsula
• Aleutian Islands
• West
• Norton Sound, Kotzebue Sound
• Bering Strait
• Nome, Wales, Shismaref
• North
• Barrow
• Prudhoe Bay
• Facilities used for this research include NWS
  Fairbanks, CIFAR, IARC, UAF, and data from
  NOAA/OAR/ESRL PSD in Boulder, Colorado, USA

Map courtesy of http//www.sonofthesouth.net/
4
Are Severe Coastal Storms becoming more Frequent?

• Methods
• NCL programs were used to pick out storms using
  the NCEP NNR I datasets
• Criteria

• Conclusion Yes, severe coastal storms in Alaska
  are increasing in frequency.

NCEP Reanalysis data
5
MethodologyStorm Comparison and Synoptic Analysis

• Bering Sea storm of October 2004
• NCEP/NCAR Reanalysis I (NNR I) data sets
• resolution of 2.5 degrees latitude/longitude
• temporal resolution, 4x daily from 1948-present
• Programs written in the NCAR Command Language
  (NCL)
• Vector based language
• Easily accessible
• Good tool for climatological analysis
• the NWSs Advanced Weather Information Processing
  System (AWIPS) products for further analysis
• 3 separate severe events were chosen to compare
  with the 2004 storm
• October 4th, 1960
• November 12th, 1974
• September 23rd, 2005
• Storms were chosen based on the severe flooding
  they caused in Nome and the Norton Sound region

6
ResultsStorm Comparison and Synoptic Analysis

• Bering Sea Storm of October 2004
• 3 main features came together to form this storm
  and cause its rapid deepening
• Siberian low
• Had persisted for over 10 days before the Bering
  Sea storms lowest SLP
• Traced back to October 6th, 2004
• Tropical storm
• Interacted with the Siberian low
• Provided moisture for the Bering Sea storm
• Secondary low
• Formed through upper level trough amplification
• Absorbed the Siberian low
• Caused the 32 mb deepening in 24 hours

7
ResultsBering Sea storm of October 2004
Storm tracks where the Siberian feature is shown
in black and the tropical feature is shown in red
NCEP Reanalysis data
NAM95 Cross section of RH and theta on the 19th
at 00Z where northeast is to the right, from AWIPS
GFS190 Potential vorticity on the 17th at 12Z for
theta surface 310K (700-500mb level), from AWIPS
8
ResultsStorm Comparison and Synoptic Analysis

• 4 Storm Comparison

9
ResultsStorm Comparison and Synoptic Analysis

• 4 Storm Comparison

• similarities, with the exception of the 1960
  storm, were found in
• 1)upper level trough amplification
• 2)secondary low features
• 3)500 mb vorticity
• 4)thetaE (frontogenesis)
• 5)the presence of a jet streak feature
• Next page figures NCEP Reanalysis data

10
Results4 Storm Comparative Analysis
11
Next StepsStorm Comparison and Synoptic Analysis

• Coastal Storm Climatology
• Refine criteria for storm detection, including
• Locating closed centers of storms
• Pinpointing locations of high pressure gradients
• Apply the climatology results to seasonal sea ice
  charts
• Bering Sea Storms
• Use numerical models, such as the polar MM5 and
  WRF models, to investigate features of Bering Sea
  storm deepening such as
• topographic effects of the Kamchatka Peninsula
• controlling the moisture intrusion by lower
  latitude synoptic features
• removing the secondary low feature
• and, controlling the surface latent heat fluxes
• Expand the storm comparison to include other
  storms
• October 1992 storm that caused extensive
  flooding in Nome

12
Summary

• The case study aspect of this project resulted in
  several key features of rapid storm deepening for
  Bering Sea storms, particularly in the case of
  the 2004 storm
• The amplification of an upper level wave
• A jet streak feature
• Moisture intrusion by a secondary low caused by
  the trough amplification
• Storm frequencies along the Alaskan coast are
  increasing
• Diminishing ice coverage during the late summer
  is thought to be especially important for
  northern coast storms.

Total Alaska northern coast storms from
1948-2005. Includes storms along the south, west,
and north coasts. NCEP Reanalysis data
Visible satellite picture of the Bering Sea 2004
storm on the 19th at 00Z, from AWIPS
13
Acknowledgements

• Thank you for all your time and help on this
  project
• Dr. John Walsh, CIFAR and IARC
• Dr. David Atkinson, IARC and UAF
• Mr. John Dragamir, NWS WFO Fairbanks, AK
• Mr. John Lingaas, NWS WFO Fairbanks, AK
• Mr. Justin Arnott, NWS WFO Fairbanks, AK
• Dr. Martha Shulski, GI and Alaska Climate
  Research Centre
• Cooperative Institute for Arctic Research (CIFAR)
• NWS Fairbanks, AK for the use of AWIPS and data
  on the 2004 event
• NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, for
  the use of their NCEP Reanalysis data from their
  Web site at http//www.cdc.noaa.gov/
• International Arctic Research Centre (IARC) for
  an office, workstation, and the use of their
  libraries
• University of Alaska Fairbanks for accommodations
  during the summer and a building to work in!