Status Report on the Sounding-based Experiment on Mixed Precipitation Events (SEMPE) Douglas Miller UNC Asheville Laurence Lee NOAA/National Weather Service, Greer, SC

Outline Background Purpose Status Making lemonade out of lemons Collaborations Upcoming research Future field programs 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

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 from 680 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 IOPDate (07)PurposeSoundings (GMT) 19 JanNW flow snowfall JanMixed precipitation 1018,1155, JanMixed precipitation 1352, 1555, 1801, FebMixed 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 NOAA SAYS U.S. WINTER TEMPERATURE NEAR AVERAGE Global December-February Temperature Warmest on Record

SEMPE Making lemonade out of lemons

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 Height (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 Acknowledgements A special “thank you” to –Mr. Richard Lind - Naval Postgraduate SchoolMr. Richard LindNaval Postgraduate School –Ms. Karen Joslin - Warren Wilson CollegeMs. Karen JoslinWarren Wilson College

SEMPE

Purpose, education The 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.