SREFCALIBRATED ENSEMBLE FORECASTS AVAILABLE ON SPC WEB PAGE

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SREF/CALIBRATED ENSEMBLE FORECASTS AVAILABLE ON
SPC WEB PAGE
URL http//www.spc.noaa.gov/exper/sref/

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MODEL FORECAST and OBSERVED SOUNDINGS

• Examined extensively for threat assessment (CAPE,
  DCAPE, vertical SHEAR, moisture, lapse rates,
  etc.)?
• Viewed from NCEP operational runs and
  limited-domain high resolution runs.

CAPE Convective Available Potential Energy

CONVECTIVE INHIBITION (CIN) IS AREA TO THE
RIGHT OF PARCEL ASCENT CURVE WHEN CIN IS PRESENT
SIMULTANEOUSLY WITH CAPE, IT ACTS TO CAP
CONVECTIVE DEVELOPMENT
Vertical wind profile
CIN
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CONVECTIVE FORECASTS 0-3 hrs

• Focus on observations, model diagnostics (e.g.,
  RUC derived parameters), diagnostic imagery
  (radar, satellite, lightning)?
• Assessment relates back to ingredients (lift,
  moisture, instability, vertical shear)
• Common points of interest (mesolows, boundaries,
  convergence, instability, cap strength, vertical
  shear in VAD winds/profiler data, storm
  evolution)?
• Need to synthesize many disparate datasets to
  achieve best forecast
• Diagnostic imagery
• Model derived parameters
• Subjective analysis / mesonets
• Spotter reports
• Combine with conceptual models / experience
  (intangibles)?

The essence of nowcasting is how quickly the
forecaster can gather the information needed to
develop a three-dimensional picture of the
atmosphere in the region of concern. - J.
McGinley (Mesoscale Meteorology and Forecasting,
1986)?
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SUBJECTIVE ANALYSIS HELPS DIAGNOSEA
POORLY-FORECAST BOUNDARY AND SURFACE WAVEa
system that was responsible for 50 tornadoes,
including 2 F3s
21Z 27 July 1994
00Z 28 July 1994
03Z 28 July 1994
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BOUNDARY DETECTION IS FACILITATED BY DATA
SYNTHESIS
All data from c. 2230Z Sunday 22 June 2003
Record 6 - 7 diameter hail In Aurora, NE
(yellow square)?
BASE REFLECTIVITY
Outflow boundaries
Thermal axis
Moisture axis
MESOANALYSIS
Also useful lightning, profiler and ACARS data
VISIBLE SATELLITE
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OBJECTIVELY-DERIVED FIELDS PROVIDE VALUABLE
ASSISTANCE WITH SUBJECTIVE ANALYSIS

• Computer-drawn streamlines help locate fronts
  and other
• potential sites of storm development
• Animation of objectively-drawn derived fields
  helps forecaster
• spot influence of bad data, especially when
  displayed
• with conventional data
• Combination of computer and human skills
  maximizes
• analysis skill and, therefore, forecast
  potential

700-500mb lapse rates
0-1 km Storm-relative helicity (SRH)?
Significant-tornado parameter
SLP, 10m winds, isallobars
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Present/Future Convective Forecast Challenges

• Convective mode (i.e. discrete cells, linear
  systems, mutlicellular systems)?
• Convective Initiation (timing, placement)?
• Very low CAPE / high vertical shear, very high
  CAPE / low vertical shear
• Elevated Convection (rooted above local PBL)?
• Increase emphasis on medium and long range
  prediction
• Lightning as a hazard

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RAOB DATA DO NOT TELL THE WHOLE STORYstorm mode
often difficult to determine before convection
develops
Birmingham, AL 18z 16 Feb 2001
Birmingham, AL 18z 16 Dec 2000
CAPE 1194 J kg-1 CIN 0 J kg-1 SRH 120 m2
s-2 Shear 68 kts
CAPE 1351 J kg-1 CIN 2 J kg-1 SRH 213 m2
s-2 Shear 73 kts
Tornado and high wind reports
Bow echo / derecho
Quasi-discrete supercells
High wind reports
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CONVECTIVE INITIATION NOT ONE-SIZE-FITS-ALL

• Scale of motion often less than observational
  network can detect
• Not all boundaries are created equal (slope of
  ascent, parcel characteristics, cap strength)?
• Not all convective initiation is surface based
  (i.e. occurs on cold side of boundary)?

c
Developing Elevated Convection
Surface Moisture Flux Convergence Axis (RUC
ANALYSIS)?
SVR REPORTS
27 May 2004 VIS 1515 UTC
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Extreme CAPE / Weak vertical shear
Jarrell, TX F5 Tornado
Corpus Christi, TX sounding 27 May 1997, 12 Z
Boundary
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Weak CAPE / Strong Vertical Shear

• Accounts for many widespread damaging wind events
  during the cool season little or no lightning.
• Look for strong deep-layer QG forcing (DPVA, or
  upper-tropospheric PV)?

October 13, 2003 250 mb PV/ PV advection
(white), 300mb streamlines
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14 October 2003 21z - 15 October 2003 00z
GOES-12 WVRUC Analysis MUCAPE (GREEN)DYNAMIC
TROP HEIGHT (mb)?

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Pittsburgh, PA 0.5o Reflectivity (2034-2208
Z)Embedded mesoscale circulation forms,
producing damaging winds, surface temperatures
50s F

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Damaging Winds 14 October 2003
Damage to a Bank in Cranberry, PA 14 October
2003 Photo By Sidney L. Davis, Tribune-Review

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ACKNOWLEDGMENTS Steve Corfidi Jared
Guyer Paul Markowski David Bright
QUESTIONS? Peter.Banacos_at_noaa.gov