Elevated potential instability in the comma head

Distribution and development

Andrew A. Rosenow, Robert M Rauber, Brian F. Jewett, Greg M. Mcfarquhar, Jason M. Keeler

Research output: Contribution to journalArticle

Abstract

The development of elevated potential instability within the comma head of a continental winter cyclone over the north-central United States is examined using a 63-h Weather Research and Forecasting (WRF) Model simulation. The simulation is first compared to the observed cyclone. The distribution of most unstable convective available potential energy (MUCAPE) within the comma head is then analyzed. The region with positive MUCAPE was based from 2- to 4-km altitude with MUCAPE values up to 93 J kg-1. Backward trajectories from five sublayers within the region of elevated convection in the comma head were calculated to investigate how elevated potential instability developed. Air in the lowest sublayer, the source air for convective cells, originated 63 h earlier near Baja California at elevations between 2.25- and 2.75-km altitude. Air atop the layer where convection occurred originated at altitudes between 9.25 and 9.75 km in the Arctic, 5000 km away from the origin of air in the lowest sublayer. All air in the layer in which convection occurred originated over the Pacific coast of Mexico, the Pacific Ocean, or arctic regions of Canada. Diabatic processes strongly influenced air properties during transit to the comma head. Air underwent radiative cooling, was affected by mixing during passage over mountains, and underwent interactions with clouds and precipitation. Notably, no trajectory followed an isentropic surface during the transit. The changes in thermodynamic properties along the trajectories led to an arrangement of air masses in the comma head that promoted the development of potential instability and elevated convection.

Original languageEnglish (US)
Pages (from-to)1259-1278
Number of pages20
JournalMonthly Weather Review
Volume146
Issue number4
DOIs
StatePublished - Apr 1 2018

Fingerprint

air
potential energy
convection
trajectory
cyclone
diabatic process
thermodynamic property
distribution
air mass
simulation
cooling
weather
mountain
coast
winter
ocean

Keywords

  • Atmosphere
  • Extratropical cyclones
  • Instability
  • Snowfall
  • Trajectories
  • Winter/cool season

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Elevated potential instability in the comma head : Distribution and development. / Rosenow, Andrew A.; Rauber, Robert M; Jewett, Brian F.; Mcfarquhar, Greg M.; Keeler, Jason M.

In: Monthly Weather Review, Vol. 146, No. 4, 01.04.2018, p. 1259-1278.

Research output: Contribution to journalArticle

Rosenow, Andrew A. ; Rauber, Robert M ; Jewett, Brian F. ; Mcfarquhar, Greg M. ; Keeler, Jason M. / Elevated potential instability in the comma head : Distribution and development. In: Monthly Weather Review. 2018 ; Vol. 146, No. 4. pp. 1259-1278.
@article{a62b6dd4f9954ea0aa32a8462aa3f894,
title = "Elevated potential instability in the comma head: Distribution and development",
abstract = "The development of elevated potential instability within the comma head of a continental winter cyclone over the north-central United States is examined using a 63-h Weather Research and Forecasting (WRF) Model simulation. The simulation is first compared to the observed cyclone. The distribution of most unstable convective available potential energy (MUCAPE) within the comma head is then analyzed. The region with positive MUCAPE was based from 2- to 4-km altitude with MUCAPE values up to 93 J kg-1. Backward trajectories from five sublayers within the region of elevated convection in the comma head were calculated to investigate how elevated potential instability developed. Air in the lowest sublayer, the source air for convective cells, originated 63 h earlier near Baja California at elevations between 2.25- and 2.75-km altitude. Air atop the layer where convection occurred originated at altitudes between 9.25 and 9.75 km in the Arctic, 5000 km away from the origin of air in the lowest sublayer. All air in the layer in which convection occurred originated over the Pacific coast of Mexico, the Pacific Ocean, or arctic regions of Canada. Diabatic processes strongly influenced air properties during transit to the comma head. Air underwent radiative cooling, was affected by mixing during passage over mountains, and underwent interactions with clouds and precipitation. Notably, no trajectory followed an isentropic surface during the transit. The changes in thermodynamic properties along the trajectories led to an arrangement of air masses in the comma head that promoted the development of potential instability and elevated convection.",
keywords = "Atmosphere, Extratropical cyclones, Instability, Snowfall, Trajectories, Winter/cool season",
author = "Rosenow, {Andrew A.} and Rauber, {Robert M} and Jewett, {Brian F.} and Mcfarquhar, {Greg M.} and Keeler, {Jason M.}",
year = "2018",
month = "4",
day = "1",
doi = "10.1175/MWR-D-17-0283.1",
language = "English (US)",
volume = "146",
pages = "1259--1278",
journal = "Monthly Weather Review",
issn = "0027-0644",
publisher = "American Meteorological Society",
number = "4",

}

TY - JOUR

T1 - Elevated potential instability in the comma head

T2 - Distribution and development

AU - Rosenow, Andrew A.

AU - Rauber, Robert M

AU - Jewett, Brian F.

AU - Mcfarquhar, Greg M.

AU - Keeler, Jason M.

PY - 2018/4/1

Y1 - 2018/4/1

N2 - The development of elevated potential instability within the comma head of a continental winter cyclone over the north-central United States is examined using a 63-h Weather Research and Forecasting (WRF) Model simulation. The simulation is first compared to the observed cyclone. The distribution of most unstable convective available potential energy (MUCAPE) within the comma head is then analyzed. The region with positive MUCAPE was based from 2- to 4-km altitude with MUCAPE values up to 93 J kg-1. Backward trajectories from five sublayers within the region of elevated convection in the comma head were calculated to investigate how elevated potential instability developed. Air in the lowest sublayer, the source air for convective cells, originated 63 h earlier near Baja California at elevations between 2.25- and 2.75-km altitude. Air atop the layer where convection occurred originated at altitudes between 9.25 and 9.75 km in the Arctic, 5000 km away from the origin of air in the lowest sublayer. All air in the layer in which convection occurred originated over the Pacific coast of Mexico, the Pacific Ocean, or arctic regions of Canada. Diabatic processes strongly influenced air properties during transit to the comma head. Air underwent radiative cooling, was affected by mixing during passage over mountains, and underwent interactions with clouds and precipitation. Notably, no trajectory followed an isentropic surface during the transit. The changes in thermodynamic properties along the trajectories led to an arrangement of air masses in the comma head that promoted the development of potential instability and elevated convection.

AB - The development of elevated potential instability within the comma head of a continental winter cyclone over the north-central United States is examined using a 63-h Weather Research and Forecasting (WRF) Model simulation. The simulation is first compared to the observed cyclone. The distribution of most unstable convective available potential energy (MUCAPE) within the comma head is then analyzed. The region with positive MUCAPE was based from 2- to 4-km altitude with MUCAPE values up to 93 J kg-1. Backward trajectories from five sublayers within the region of elevated convection in the comma head were calculated to investigate how elevated potential instability developed. Air in the lowest sublayer, the source air for convective cells, originated 63 h earlier near Baja California at elevations between 2.25- and 2.75-km altitude. Air atop the layer where convection occurred originated at altitudes between 9.25 and 9.75 km in the Arctic, 5000 km away from the origin of air in the lowest sublayer. All air in the layer in which convection occurred originated over the Pacific coast of Mexico, the Pacific Ocean, or arctic regions of Canada. Diabatic processes strongly influenced air properties during transit to the comma head. Air underwent radiative cooling, was affected by mixing during passage over mountains, and underwent interactions with clouds and precipitation. Notably, no trajectory followed an isentropic surface during the transit. The changes in thermodynamic properties along the trajectories led to an arrangement of air masses in the comma head that promoted the development of potential instability and elevated convection.

KW - Atmosphere

KW - Extratropical cyclones

KW - Instability

KW - Snowfall

KW - Trajectories

KW - Winter/cool season

UR - http://www.scopus.com/inward/record.url?scp=85047078010&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85047078010&partnerID=8YFLogxK

U2 - 10.1175/MWR-D-17-0283.1

DO - 10.1175/MWR-D-17-0283.1

M3 - Article

VL - 146

SP - 1259

EP - 1278

JO - Monthly Weather Review

JF - Monthly Weather Review

SN - 0027-0644

IS - 4

ER -