Warn on Forecast Case Studies: Progress Report February 2012. Lou Wicker (NSSL). Contributors Dusty Wheatley (NSSL/CIMMS) Nusrat Yussouf (NSSL/CIMMS) Dan Dawson (NSSL/CIMMS) Ted Mansell (NSSL) Corey Potvin (NRC PostDoc) Robin Tanamachi (CAPS/OU). Thomas Jones (NSSL/CIMMS) - PowerPoint PPT Presentation
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• Tornadic supercells • 8 May 2003 OKC F4 tornado• 4 May 2007 Greensburg KS EF5 tornado• 27 April 2011 MS/AL/TN superoutbreak• 10 May 2010 Central OK outbreak
• Downburst• 14 June 2011 Norman macroburst
• Mesoscale convective systems• 4 July 2004 IN/OH/KY derecho (BAMEX)• 14 June 2010 W TX tornado / flash flood (VORTEX2)
Warn on Forecast Workshop 8-9 February 2012
May 8, 2003 Oklahoma City Tornadic Supercell
Damage Path of OKC Tornado
Hu and Xue (2007)
HPC Synoptic Scale Surface Analyses at 18:00 UTC
KOUN Radar Observations at 22:10 UTC
Nusrat Yussouf
Warn on Forecast Workshop 8-9 February 2012
8 May 2003: Multiscale experiment EnKF used at multiple scales
Mesoscale Ensemble• 45 member WRF mesoscale ensemble at 18 km horizontal grid spacing over CONUS initialized from GFS • 3 day cycling with assimilation of routinely available observations from
metar, marine, radiosondes and ACARS using DART system• Physics options used: MYJ, Thompson, Kain-Fritsch, Noah, Dudhia and RRTM
Storm-scale Ensemble• 45 member storm-scale ensemble nested down from the 45 member mesoscale ensemble data system• 2-km horizontal grid spacing, 225 x 180 x 50 grid points• Assimilates KTLX radar radial velocity and reflectivity observations every 3-min
for a one-hour period
T - 3 days 8 May
Nusrat Yussouf
Warn on Forecast Workshop 8-9 February 2012
Reflectivity, Vorticity and Horizontal Winds at 1 km AGL
KTL
X Re
flect
ivity
at 2
2:01
UTC
Fina
l Ana
lyse
s at 2
2:00
UTC
30 m
in F
orec
ast a
t 22:
30
UTC
15 m
in F
orec
ast a
t 22:
15
UTC
Ensemble Member #9
Vorticity contours: 0.005 to 0.01 by 0.001
KTL
X Re
flect
ivity
at 2
2:16
KTL
X Re
flect
ivity
at 2
2:31
UTC
Nusrat Yussouf
mesocyclonemesocyclone
Warn on Forecast Workshop 8-9 February 2012
Probability of Vorticity During 45-min Forecast Period
22:00 – 22:45 UTC
Observed damage track and times
~22:06
~22:38
≥ 0.003 s-1 at 1 km
≥ 0.005 s-1 at 3 km
Probability (%)
~22:38
Observed damage track and times
~22:06
~22:38
Nusrat Yussouf
Warn on Forecast Workshop 8-9 February 2012
Greensburg KS (2007)• EnKF analysis and prediction of the significant tornadic storm on 5 May 2007 storm near Greensburg, KS
• Single radar retrieval using DDC Vr & dBz
• Homogeneous initial environment
• Examined sensitivity to low-level wind profile and (to a lesser extent) microphysics
27 April 2011 Tornado Outbreak:EnKF Radar DA and Ensemble Forecasts
45-member WRF-ARW ensembles (Δx=3 km) initialized from Rapid- Refresh model (Δx=13 km) at two times (1900 and 2100 UTC)
Data from 4 radars assimilated every 3 min for 1 hKBMX, KDGX, KGWX, KHTXadditive noise only source of ensemble spread
Ensemble forecasts produced after radar DA
19Z 20Z 21Z 22Z 23Z
21Z 22Z 23Z
RadarDA
Experiment 2: 2100-2200 UTC initialization KDGX
KGWX
KHTX
KBMX
observedtornadotracks
ensembleforecast
ensembleforecast
RadarDA
David Dowell
Warn on Forecast Workshop 8-9 February 2012
Two Ensemble Forecasts:initialized at different times, valid at same time
Ensemble-Based Probabilities of Rotating Updrafts2200-2300 UTC 27 April 2011
2-3 h forecastinitialized at 2000 UTC
0-1 h forecastinitialized at 2200 UTC
northern swath of high probability changed
relatively little
southern swath moved significantly based on
recent radar data and/or RR mesoscale analysis
David Dowell
Warn on Forecast Workshop 8-9 February 2012
0-1 h ForecastEnsemble Member 1
2-5 km AGL Max Updraft Helicity2200-2300 UTC
observedcomposite reflectivity
NSSL/Q2 Mosaic3D2200 UTC
observedtornadotracks
model maintains long-livedstorms initialized in
Tuscaloosa County andCullman/Blount County
David Dowell
Warn on Forecast Workshop 8-9 February 2012
• Measured wind gusts > 36 m/s (130 km/hr)• Wind-driven golf ball or larger hail• 33,000 residents without power for over a day• Residential damage took > 4 months to repair
Warn on Forecast Workshop 8-9 February 2012Dusty Wheatley
Simulated reflectivity from sample members at 0030 UTC 5 July
Warn on Forecast Workshop 8-9 February 2012
EnKF analyses of 2-m temperature
With the assimilation of sub-hourly surface data, the mesoscale cold pool is better developed at the last analysis time (2300 UTC) and subsequent forecast times.
2300 UTC 4 Jul 30 min fcst 60 min fcst 90 min fcst
Radar DA only
Inc. sub-hourlysurface DA
Dusty Wheatley
Warn on Forecast Workshop 8-9 February 2012
June 14, 2010 west-TX VORTEX2 event
6-h QPEs ending 00Z 15 June 2010
NSSL Q2
Stage IVx LBB
2. Flash flood:
- HP supercell with weakly tornadic mesocyclone along gust front/pre-existing boundary intersection
- Severe wind gusts (34 – 37 m s-1 measured by VORTEX2) and strong cold pool (ΔT 15 - 18 K)
1. Severe weather: x LBB
x LBB
6”+ max 3”+ max
100 km100 km
1937 UTC
Focus area
Mike Coniglio
Warn on Forecast Workshop 8-9 February 2012
Initial mesoscale assimilation tests: Final analysis valid 18 UTCEnKF mean RUC analysis
RMSD = 1.90ME = 0.19
RMSD = 2.35ME = 0.47
2-m T
2-m Td
RMSD = 1.70ME = 0.51
RMSD = 2.10ME = 0.54
EnKF mean reduces analysis errors vs. RUCBut moist bias remains (MYJ PBL scheme)
Mike Coniglio
Warn on Forecast Workshop 8-9 February 2012
1 Hour Radar Assimilation Experiments: Final analysis valid 19Z
Mike Coniglio
Warn on Forecast Workshop 8-9 February 2012
Total 3-h accumulated precipitation 19-22 UTCNMQ QPE (color shading) and ensemble raw
probabilities > 10 mm (contours)
1-radar 4-radars
More backbuilding, slowereastward movement, butstill too far east overall
Little to no backbuilding, convection moves too fast to east
Accumulation too low in most runsMike Coniglio
Warn on Forecast Workshop 8-9 February 2012
GOES Cloud Property Assimilation using WRF-DART
• Initial Implementation: convert NASA Langley retrieval algorithm cloud properties into proxy WRF state variables
• Use Cloud Top Pressure (CTP) and Cloud Base Pressure (CBP) to determine 3-D location of cloud