warn on forecast case studies: progress report february 2012
DESCRIPTION
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 PresentationTRANSCRIPT
Warn on Forecast Workshop 8-9 February 2012
Warn on Forecast Case Studies:
Progress Report February 2012
• 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)•Mike Coniglio (NSSL)•Adam Clark (NSSL/CIMMS)•James Corriea (SPC)•Terra Thompson (NSSL/OU)
Lou Wicker (NSSL)
Warn on Forecast Workshop 8-9 February 2012
PurposeTo test storm-scale NWP in a
variety of severe weather situations• Two basic classes of events
• isolated cells• mesoscale convective systems
• Basic questions to be answered:• core sets of observations needed• accuracy needed of background analysis for
convective scale forecasts• analysis versus prediction• predictability (0-1, 0-3, 0-6 hours?)
Warn on Forecast Workshop 8-9 February 2012
Cases• Isolated Cells
• 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
Dan Dawson
Warn on Forecast Workshop 8-9 February 2012
Probabilistic Vorticity Forecast (All 9 experiments)
Background VAD Profile (UTC) Used 0130 0200 0230
60 min forecasts
45 min forecasts
Dan Dawson
Experiment 1: 1900-2000 UTC initialization
Warn on Forecast Workshop 8-9 February 2012
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
http://www.srh.noaa.gov/oun/?n=events-20110614
dBZ 0030 UTCDownburst
June 14 Macroburst
Lou Wicker
Warn on Forecast Workshop 8-9 February 2012
2245 Vis
Mesoscale Environment
Weak elevated convection
ongoing for hours
Cold Front
CAPE~200
CAPE~2200LCL~730 mb
deep convection initiates ~2330 UTC
CAPE~3200LCL~730 mb
Lou Wicker
Moderate shear
Warn on Forecast Workshop 8-9 February 2012
Model Analysis vs Radar Obs at 0010 UTC
35 min of radar DA8 radar volumes
KOUNLocation
Lou Wicker
Warn on Forecast Workshop 8-9 February 2012
20 minute Ensemble Forecasts of Svr Wind (0030 UTC)
Verification Wind PlotVectors: Wind speed > 10 m/s
Color: 20 m/s < wind speed < 40 m/s
EnsemblePrediction
for SVR SFCWINDS
Ensemble Forecast Output ofSevere Wind ProbabilityVectorsWind speed > 20 m/s Color at least 33% of members have 25 m/s < wind speed < 40 m/s
Lou Wicker
3DVAR SFC WIND FIELD
Warn on Forecast Workshop 8-9 February 2012
The 4-5 July 2003 MCS event
2130 UTC
0200 UTC0030 UTC
2300 UTC
- Observed during BAMEX
- Produced 100+ wind reportsacross Indiana and Ohio
- Contributed to record floodingacross north-central Indiana
- Not captured in NWP models of the day (including the WRF model)
Dusty Wheatley
Warn on Forecast Workshop 8-9 February 2012
From Davis et al. 2005
Satellite imagery from 4 July 2003
Outflow boundary
Gravity wave
4 July 2003 MCS
Sensitivity to previous convection
Depicts movementof two earlier systems
Dusty Wheatley
Warn on Forecast Workshop 8-9 February 2012
EnKF analyses at 2300 UTC
OBS
• 1.5-km AGL simulated reflectivity• 2-m temperature (deg C)• 10-m winds (full barb = 10 ms-1)
Radar DA only
Sub-hourly surface data
Better cold pool analysis
Radar + Sfc DA
Surface data DA needed on storm-scale grid
Dusty Wheatley
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
• Create QCLOUD, QICE, QGRAUPEL, QRAIN, Relative Humidity
• Proxy columns on GOES horizontal grid with ~50 hPA vertical resolution
Thomas Jones
Warn on Forecast Workshop 8-9 February 2012
GOES Visible & CTP/CBP2045 UTC
• Convection initiating ahead of dryline in OK• Low-level clouds present in eastern OK
Cirrus Outflow
Low-level cloudsCTP ~200 hPa
CTP ~800 hPa
DevelopingConvection
Thomas Jones
Warn on Forecast Workshop 8-9 February 2012
WRF-DART Characteristics• WRF-DARTWRF-DART
– ARW, version 3.2.1 – EnKF assimilation using 36 members– Use 15 km CONUS and 3 km one-way nested grid
domains– Mesoscale assimilation window from 1200 UTC – 2100
UTC 10 May• 1 hour intervals
– Nested grid assimilation 1800 – 2100 UTC• 15 minute intervals
• Create 2 runs:– One assimilating derived cloud and humidity
variables (CLD)– One with variables set to evaluate-mode only
(NOCLD)
15 km Domain
3 km Domain
Thomas Jones
Warn on Forecast Workshop 8-9 February 2012
QCLOUD Differences2045 UTC
RED = CLD Greater BLUE – NOCLD Greater
Large areas of differences at 900 and 850 hPa
Magnitude ~ 0.1 g kg-1
Greatest differences near developing cumulus and in low-level clouds fields further east
Interesting wave-like pattern in QCLOUD differences at 850 hPa
Differences at 700 hPa and above have limited coverage
Only significant differences occur along dryline
Also see differences in model IWP (black shading)
Hard to ascertain physical significance of these differences
Thomas Jones
Warn on Forecast Workshop 8-9 February 2012
1 hour reflectivity forecast
• Probability of simulated reflectivity > 25 dBZ changes between NOCLD and CLD ensembles
• Neither shows much skill relative to the other
Thomas Jones
Warn on Forecast Workshop 8-9 February 2012
Summary• Two supercell cases: SS-NWP can predict the track
of the strongest rotation with some accuracy in 0-1 hour time frame.
• Using tornado proxy for track - less skill with genesis/decay
• Microphysical parameterization strongly impacts the forecast at these scales.
• Need to test cases from environments with more marginal tornado parameters
• Initial macroburst forecast is promising
Warn on Forecast Workshop 8-9 February 2012
Summary• Mesoscale convective systems
– accurate depiction of mesoscale environment critical
– Multi-radar improved QPF predictions
• Satellite case
– Takes 2 hours of assimilation of cloud properties to start making a difference
– GOES-R should reduce this time by providing 5 – 10 minute resolution data.
– Results likely very sensitive to microphysics
Warn on Forecast Workshop 8-9 February 2012
Take Aways..• Prediction of isolated severe convection shows promise
– MCS’s appears to have more challenges
• Everything matters?
– success with isolated cells: getting the (enough) details right over a small area?
– MCS problem may require getting the details right over a much larger area...
• Its the boundary layer....
– much of forecast error can be traced (we think) to errors in boundary layer structure of humidity and temperature
– all phases of convective evolution (initiation, intensification, decay) are impacted by these errors (even tornadogenesis?)
Warn on Forecast Workshop 8-9 February 2012
Thanks Questions?
Warn on Forecast Workshop 8-9 February 2012
Verification
TimingVerification with Tornado reports
Model proxy Tornado
Members shifted and focused more north than observed with minimal members co-located with TOR
Obs cell density axes (30 min)
Spatial location
UH
CA
# members
# storms - # storms verified
Establishing metrics of success
Which DA verifies best?Percent severe Percent model severe
25 50 75 100%Being storm specific next hour
A. No threat now
B. Tornado threat in 30 min
C. Decaying threat (storm ongoing)
• Explicit forecast of which storms will be severe and which won’t
A
C
B
Storm Severe Storm
Warn on Forecast Workshop 8-9 February 2012
Warn on Forecast Workshop 8-9 February 2012
Warn on Forecast Workshop 8-9 February 2012
Microphysical ParameterizationDevelopment
(T. Mansell, D. Dawson, Y. Jung, M. Xue)
• Development of 3-moment microphysical scheme suitable for deep convection
• Testing of 3-moment scheme within EnKF framework
• Verification of microphysical parameterizations– using dual-polarization radar data
– forward operator from Y. Jung and M. Xue
– collaboration with CAPS
Warn on Forecast Workshop 8-9 February 2012
Observations 8 May 2003 22:10 (tornadogenesis)
22 minute ensemble mean forecastwith multi-moment microphysics
valid 22:10
22 minute ensemble mean forecastwith single-moment microphysics
valid 22:10
Microphysical Sensitivity
Warn on Forecast Workshop 8-9 February 2012
Microphysical SensitivityGreensburg KS Forecasts
Single vs. Two Moment Microphysics
Single Two
Warn on Forecast Workshop 8-9 February 2012
Warn on Forecast Workshop 8-9 February 2012
GOES Cloud Property Assimilation• GOAL: Provide model analysis information on the location
and vertical distribution of clouds• Need high spatial and temporal resolution data• 1 km, 30 minute cloud property retrievals available from
GOES-13 data– Uses NASA Langley retrieval algorithm – Products include:
• Cloud top pressure (CTP)• Cloud base pressure (CBP)• Cloud liquid water path (CLWP)• Cloud ice water path (CIWP)• Cloud phase
• These variables are not suitable for direct assimilation into WRF-DART– Must convert to something it understands
Warn on Forecast Workshop 8-9 February 2012
Observation Diagnostics • QCLOUD
– No difference in bias or RMSE between 18-2000 UTC
– Some reduction in bias and RMSE after 2000 UTC
• Reduction increases with time• Max reduction ~0.05 g kg-1
RH Differences small at all times Posterior bias and RMSE at 2100 are
smaller by ~0.5%
Sample size ~800 Q* data points assimilated at each
time interval Total possible: ~1300
~300 for RH Saw-tooth pattern a result lower sample
size at interpolated times (00, 30)
Warn on Forecast Workshop 8-9 February 2012
QCloud and RH Data at 2045 UTC
• Where low clouds exist, RH=100% assimilated• Above 850 hPa, few clouds resulting in QCLOUD = 0 being assimilated
VARIABLE NTOTAL NASSIM %ASSIMQCLOUD 205482 187042 91.0QICE 205482 190796 92.8QRAIN 205482 190380 92.6QGRAUP 205482 196392 92.6RH 37189 22357 60.1TOTAL 859117 780967 90.9
1800 – 2100 UTC
Sample size
50
QCloud data
RH data
Thomas Jones
Warn on Forecast Workshop 8-9 February 2012
Cross Sections
• Small differences in location of QCLOUD peaks– 5-10 km offset
• Magnitude of IWP also differs
QCLOUD IWP
Warn on Forecast Workshop 8-9 February 2012
Issues/Challenges to Explore
• Case-specific challenges/questions:– Event has multiple convective modes and a strong cold pool. Can Δ=3 km simulations
produce a strong cold pool while still restraining its eastward propagation, as was observed?
2011 CAPS 4-km runs
TTU SND 1732
Currently trying experiment with MYNN Bnd LYR scheme
Environment from MYNN (MYJ) run from 2011 CAPS ensemble one of the best (worst) fits to observed soundings (see poster for more info).
Low-level moist bias in the warm sector- will multiple PBL/land-surface schemes help? Only using MYJ currently.
EnKF mean T, Td 1800
Mike Coniglio
Warn on Forecast Workshop 8-9 February 2012
10 minute Ensemble Forecasts of Svr Wind (0020 UTC)
Lou Wicker
Verification Wind PlotVectors: Wind speed > 10 m/s
Color: 20 m/s < wind speed < 40 m/s
EnsemblePrediction
for SVR SFCWINDS
Ensemble Forecast Output ofSevere Wind ProbabilityVectorsWind speed > 20 m/s Color at least 33% of members have 25 m/s < wind speed < 40 m/s
3DVARSFC
WINDFIELD
Warn on Forecast Workshop 8-9 February 2012
15 minute Ensemble Forecasts of Svr Wind (0025 UTC)
Lou Wicker
Verification Wind PlotVectors: Wind speed > 10 m/s
Color: 20 m/s < wind speed < 40 m/s
EnsemblePrediction
for SVR SFCWINDS
Ensemble Forecast Output ofSevere Wind ProbabilityVectorsWind speed > 20 m/s Color at least 33% of members have 25 m/s < wind speed < 40 m/s
3DVARSFC
WINDFIELD
Warn on Forecast Workshop 8-9 February 2012
Verification: Surface Winds Derived from 3DVAR Analysis
Three-radar wind synthesisKTLX, KOUN, TDWR
0010 UTC
Poorretrieval of winds nearsouthernboundary
Gust FrontfromDownburst0020 UTC
0030 UTC
Lou Wicker