Status Report on the Sounding-based Experiment

on Mixed Precipitation Events (SEMPE) 2006-2007

Douglas MillerUNC Asheville

Laurence LeeNOAA/National Weather

Service, Greer, SC

Outline

• Background

• Purpose

• Status

• Making lemonade out of lemons

• Collaborations

• Upcoming research

• Future field programs

SEMPE

SEMPE

• Background, 15 December 2005

photo by John Cunningham

SEMPE

• 15 December 2005

photo by David P. Smith

SEMPE

• 15 December 2005

analysis and graphic by Patrick Moore

SEMPE

• 15 December 2005

table by Patrick Moore

http://www.erh.noaa.gov/gsp/localdat/lcldata.htm

SEMPE

• 15 December 2005

analysis and graphic by Patrick Moore

• Cold air damming climatology

SEMPE

figure from Bell and Bosart (1988)

• Cold air damming antecedent synoptic scale structure

SEMPE

SLP

figures from Bell and Bosart (1988)

SEMPE

• Freezing rain schematic

(courtesy Brooks Martner)

SEMPE

• Background

USGS DEM topography map

Swannanoa River Basin

Elevation gain from680 to 6800 feet

SEMPE

• Purpose, research– Examine certain aspects of the cold air

infiltration through the mountains during damming events

SEMPE

• Purpose, research

The study addresses two of the highest priority items for research as listed by the NWS Office of Science and Technology:

The effect of topography and other surface forcing on local weather regimes

Locally hazardous weather, especially severe convection, winter weather, and phenomena that affect aviation

SEMPE

• Purpose, education

SEMPE

• Purpose, education– Improve the quality of education for

the undergraduate students enrolled at the University of North Carolina Asheville (UNCA)

• through the increased awareness of the NWS operational problems and needs

• through the direct involvement of research in conducting the soundings and in analyzing the event case studies

SEMPE• Purpose, operations

– Model validation of the operational NAM and of local workstation mesoscale models (e.g., WRF). The high temporal resolution of the soundings will provide a good data set to compare against the model output, including the BUFR soundings.

– Directly helps the NWS meet two of its Government Performance Results Act (GPRA) goals

• Winter Storm Warning Accuracy (Probability of Detection)

• Winter Storm Warning Lead Time– Provide excellent training opportunities for next year and

beyond • Winter Advanced Warning Operations Course

(AWOC)

SEMPE

• Status – location,

SEMPE• Status

IOP Date (07) Purpose Soundings

(GMT)

1 9 Jan NW flow snowfall

1810

2 18 Jan Mixed precipitation

1018,1155, 1424

3 21 Jan Mixed precipitation

1352, 1555, 1801, 2045

4 1 Feb Mixed precipitation

1102, 1301, 1507, 1701, 1846

SEMPE

• Status, 12-h forecast valid 1200 UTC 1 Feb 2007

ETA RUC

SEMPE

• Status, RUC analysis valid 1200 UTC 1 Feb 2007

SEMPE

• Making lemonade out of lemons

http://www.noaanews.noaa.gov/stories2007/s2819.htm

NOAA SAYS U.S. WINTER TEMPERATURE NEAR AVERAGEGlobal December-February Temperature Warmest on Record

SEMPE

• Making lemonade out of lemons

http://www.noaanews.noaa.gov/stories2007/s2819.htm

SEMPE

• Making lemonade out of lemons (thru April)– Mixed precipitation– NW flow snowfall– “Snowstorm of the Century”

– Diurnal evolution of boundary layer• COMET fire weather model study – Dr. Etherton

– Convection crossing the mountains– Windstorm events

SEMPE

• Collaborations– Prof. Baker Perry (Appalachian State Univ.)– Prof. Sandra Yuter (NC State Univ.)

• Ku-band radar• disdrometer• weighing gauge

Weighing Rain Gauge

Parsivel Disdrometer

MicroRainRadar

Instrumentation behind Perry residence (3340 ft, 81º 54’48” W, 36º 15’09” N)

MRR Summary: 12Z 9 Jan to 01Z 10 Jan (4.0” snow – 0.31” swe)

SEMPE

• Collaborations

– Ken Galluppi, Jessica Proud (Renci)

MRR Reflectivity Data• Shows amount of power returned to radar from precipitation• Power return depends on the number and size of precip

Snow begins to fall aloft, but evaporates before it hits the ground

No precip aloft at this time

Dry layer moistening,

snow reaches ground

Snow begins to fall again Snow

changes over to sleet

~11:40

Sleet changes

over to rain and

sleet/rain

mix Precip ended

Hei

ght

(ft)

Time (4am-2:20pm)

No precip at surface

~2.5 hr of no precip

SEMPE

• Upcoming research– Systematic comparison between model

soundings and SEMPE soundings– Case study analysis

• 1 February 2007

– Topographic-based modeling studies • WRF-ARW• WRF-EMS (NMM)

SEMPE

• Future field programs– SEMPE0809– HMT East

• Warm season

– Continuous program?• Educational benefits• Operational benefits

SEMPE

• AcknowledgementsA special “thank you” to– Mr. Richard Lind - Naval Postgraduate School

– Ms. Karen Joslin - Warren Wilson College

SEMPE

SEMPE

• Purpose, educationThe proposed COMET Outreach Partner

Project is to take observations of vertical profiles of temperature, moisture, and wind during synoptic events that are favorable for mixed precipitation (any combination of snow, sleet, and freezing rain) in order to provide more information about the nature and evolution of the cold air damming that leads to significant freezing precipitation accumulations.