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Forecasting Convective Mode and Severity. Mark F. Britt National Weather Service St. Louis, MO Mark.Britt@noaa.gov. Why Am I Here?. A Basic Review of Severe Thunderstorm Forecasting. Examine moisture return, instability, and shear calculations.

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forecasting convective mode and severity

Forecasting Convective Mode and Severity

Mark F. BrittNational Weather ServiceSt. Louis, MO

Mark.Britt@noaa.gov

why am i here
Why Am I Here?

A Basic Review of Severe Thunderstorm Forecasting.

  • Examine moisture return, instability, and shear calculations.
  • Examine how the amount and distribution of instability, vertical shear, and forcing interact to determine cell type, convective mode (linear or discrete), and coverage.
  • Determine what type(s) of severe weather to expect for a given environment.
using numbers
Using Numbers
  • There are NO “magic” numbers or thresholds. They are merely guidelines.
  • Best to look where several key parameters overlap instead of depending on one index.
  • You should look at skew-Ts and hodographs (observed and forecast) to better understand what the numbers mean.
  • Increase your situation awareness by using near storm environment data, but do not use it solely to make warning decisions.
objective analysis
Objective Analysis
  • Available on AWIPS using MSAS, LAPS, or RUC40 analysis(Thompson et al. (2003)found RUC analysis is a reasonable proxy to observed soundings in supercell environments, except it can be too cool and dry at the lowest levels.)
  • Or, the SPC Mesoanalysis Page:

http://www.spc.noaa.gov/exper/mesoanalysis/

      • Displays a national and seven movable regions that is usually available by 20 minutes past each hour
      • Displays a robust set of hourly objective analysis datasets using the latest surface observations and upper air analysis from the RUC. Depicted contours highlight important “thresholds”.
ingredients for deep moist convection
Ingredients for Deep, Moist Convection
  • Moisture: (Gulf of Mexico, evapotranspiration)
  • Instability: (Steep lapse rates either from the Elevated Mixed Layer off the Rockies, or large scale “dry” ascent ahead of a trough.)
  • Forcing: (Surface frontal boundary, convective outflow, 900-800mb moisture convergence at nose of nocturnal low level jet, orographic lift over the eastern Ozarks)
moisture return
Moisture Return

Lanicci and Warner (1991)

  • Look for rapid moisture advection from the Gulf of Mexico in strong pressure gradients ahead of a strong storm system.
  • Ridging associated with surface highs in or near the Gulf can inhibit moisture return.
  • Be cognizant of how much dry air is over the Gulf (deep cold front penetrations of cold fronts, buoy data, and Blended Total Precipitable Water:

http://amsu.cira.colostate.edu/GPSTPW/default.htm

assessing instability
Assessing Instability

Which is best?

  • SBCAPE
  • MLCAPE
  • MUCAPE
slide8

Courtesy Peter Banacos, SPC (2003)

SBCAPE: Surface Based. Uses the surface temperature and dew point. Will show large diurnal swings. Can give significant overestimates (an order of magnitude) in cases of shallow moisture and underestimates in cases of elevated convection.

slide9

Courtesy Peter Banacos, SPC (2003)

MLCAPE: Mean Layer. Uses the mean temperature and mean mixing ratio in the lowest part of the atmosphere (SPC uses lowest 100 mb). Less variable in time and space, and more conservative than MUCAPE when lower atmosphere is not well mixed.

slide10

Courtesy Peter Banacos, SPC (2003)

MUCAPE: Most Unstable Parcel. Uses most unstable parcel in lower atmosphere (SPC uses lowest 300mb). Helps with nocturnal or other types of elevated convection.

what do i do with this
What Do I Do With This?

?

RUC MUCAPE -March 12, 2006 @ 17Z

what do i do with this12
What Do I Do With This?

NAM MUCAPE - March 12, 2006 @ 17Z

surface based parcels
Surface Based Parcels

Violent tornado outbreak over western Missouri.

KSGF RAOB

May 5th, 2003 @ 00Z

elevated based parcels
Elevated Based Parcels

Numerous Reports of Hailin Eastern NE/ Western IA

KOAX RAOB

May 4th, 2003@ 18Z

cape vs parcel selection
CAPE vs. Parcel Selection

April 20, 2004

Mean Layer CAPE

Surface Based CAPE

From Jon Davies Webpage

slide16

How Tall is the CAPE?

April 20th, 2004 @ 22Z

From Jon Davies Webpage (http://members.cox.net/jdavies1/)

how tall is the cape
How Tall is the CAPE?

April 20th, 2004

From Jon Davies Webpage

how wide is the cape
How Wide Is the CAPE?

COMET

Larger differences between parcel temperature and the environmental temperature means stronger updrafts that are less susceptible to entrainment.

lapse rates
Lapse Rates
  • Craven (2000) found in a study of 65 major tornado outbreaks that 6.7o C/km is a useful lower limit. He also found low shear environments that produce tornadoes have steeper lapse rates.
  • Steep mid level lapse rates (850-500 mb) have more conditional instability and increased CAPE.
  • Steep low level lapse rates (0-3km AGL) can give a better idea on how quickly convection will develop.
mid level lapse rates
Mid Level Lapse Rates

500mb Heights/500-700mb Lapse Rates -- May 2003

Friday, May 9th @ 12Z

slide21

500mb Height/500-700mb Lapse Rates – March 11-12, 2006

Mid Level Lapse Rates

Sat Morn – 12Z

Sat Eve – 00Z

Sun Eve – 00Z

Sun Morn – 12Z

inhibiting factors
Inhibiting Factors
  • Boustead (2007) theorized that subsidence from a shortwave ridge caused a “null” “High Risk” day in the central Plains in June 1999.

12, 18, & 00Z @ OAX – 06/5-6/1999

assess vertical shear
Assess Vertical Shear
  • Distribution of vertical shear will determine dominant thunderstorm type.
  • Can be determined using either:
    • Traditional fixed layers (0-6km bulk shear, 0-1km SRH)
    • “Effective” shear which accounts forsounding dependentinflow layer through CAPE and CIN constraints. (Large sample testing suggests that “effective layer” is best defined by CAPE>100 J/kg and CIN>-250 J/kg. (Thompson 2007)). Effective shear on mesoanaylsis data is dependent on correct RUC soudings.
  • Low level curvature can determine if right-movers, left-movers, or both kinds of splits are favored.
storm type ordinary cells
Storm Type: Ordinary Cells
  • Dominant Type in Weak Shear Environments
  • Pulse Type Severe Storms.

COMET

storm type multicells
Storm Type: Multicells

COMET

Moderate to strong shear is confined mainlyto the lower levels (0 to 3 km AGL)

organized multicells
Organized Multicells
  • >40kt 0-6 km shear
  • >30kt 700-500mb wind
  • Dry (low theta-e) midlevel air (strong cold pool)
  • Downshear SBCAPE max
  • System relative convergence acting downshear to enhance forward propagation
storm type supercells
Storm Type: Supercells
  • Thompson et al. (2003) found that 90% of the 2” diameter hail reports were caused by supercells.
  • Recent work showed that from only 25% (Trapp et al. 2005) to as few a 3% (Jones et al 2004) of radar-detected mesocyclones were actually associated with tornadoes.
deep shear magnitude
Deep Shear Magnitude
  • 0-6 km layer shear “thresholds”:
    • 40+ kts: if storms develop -- supercells are likely (provided convective mode favors cellular activity)
    • 30-40 kts: supercells also possible if environment is very or extremely unstable as storm can augment local shear (>5,000 J/kg (Burgess (2003))
    • About 15-20 kts:shear needed for organized convection (multicell or supercell) with mid level winds at least 25 kt
  • Supercells become more probable as the effective bulk shear vector increases in magnitude through the range of > 25-40 kts. (Thompson et al., 2004b)
  • While 0-6km shear is a good discriminator between cell types, it isn’t a good tornado forecast tool (Thompson et al, 2002).
  • Houston et al. (2008) found in a study that compared 250 non-supercell soundings to 829 supercell soundings that the best fixed layer shear depth to discriminate between the two is 0-5 km.
deep shear magnitude29
Deep Shear Magnitude

Bunkers et al. 2006 found that in a study of 440 supercells that:

  • Long-lived supercells (those lasting >4 hrs) occur in environments with much stronger 0-8km bulk wind shear ( > 50 kt) than that observed with short-lived supercells.
  • Long lived supercells produce notably more F2–F5 tornadoes when compared with short-lived supercells, and a single long-lived supercell can also produce a substantial amount of nontornadic severe weather.
0 6 km shear magnitude
0-6 km Shear Magnitude

Supercells

Non-Supercells

From Thompson et al (2002)

supercell composite parameter scp thompson et al 2004a
Supercell Composite Parameter (SCP)(Thompson et al, 2004a)

The SCP is a multi-parameter index that includes effective SRH, muCAPE, and effect Bulk Shear. Each parameter is normalized to supercell “threshold” values. It is conditional on having discrete storms develop.

SCP = (muCAPE / 1000 J kg-1) *

(ESRH / 50 m2 s-2) * (EBWD / 20 m s-1)

EBWD is divided by 20 m s-1 in the range of 10-20 m s-1. EBWD less than 10 m s-1 is set to zero, and EBWD greater than 20 m s-1 is set to one.

(Computed every hour on the SPC Mesoanalysis Page.)

what causes supercell type
What Causes Supercell Type

Rasmussen and Straka (1998) found in an observational study of 43 isolated supercells that supercell type depends on the precipitation efficiency of the storm which is based on its ingestion of hydrometeors.

classic supercells
Classic Supercells
  • The real “value” of a CL supercell is that it appears to be the most efficient of the three types to produce significant tornadoes.
  • Can occur nearly anywhere in U.S. when NSE supports them.
high precipitation hp supercells36
High Precipitation (HP) Supercells
  • Lower mid-level and anvil-relative flow.
  • Interactions with other storms – “seeding”, more storms can occur with weak caps.
  • Typically associated with weaker tornadoes, but can produce significant tornadoes (Plainfield IL).
  • More of a severe wind (Pakwash), hail, and flash flooding threat.
  • Are the more-common supercell type east of the Mississippi owing to NSE conditions there (weaker caps, etc.), and may be the most common type everywhere in the U.S.
supercell dimensions

Pond Bank PA

Falcon Co

Hurr. Opal

Cone of Silence

Horizontal

Dimension

“mini”

“mini”

“large”

Vertical

Dimension

“low-topped”

“high-topped”

“low-topped”

Supercell Dimensions

Burgess (2003)

supercell movement
Supercell Movement

Bunkers et al (2000)

A physically based, shear-relative, and Galilean invariant method based on 290 supercell hodographs.

supercell movement39
Supercell Movement

Bunkers and Zeitler (2000)

  • There are some caveats to this method:
  • Stronger deep-layer vertical wind shear (0-6 km) leads to a stronger mesocyclone and thus to greater deviation from the mean wind.
  • Weaker mid-level storm-relative winds allow for a stronger cold pool, and thus a tendency for the supercell to move rapidly downshear.
  • Depth of thunderstorms need to be considered.
  • Supercell motion can be altered by wind shear from boundaries and orography.
  • It is surface based. (Thompson, et al., 2007)
what s the problem
What’s the Problem?
  • Evans and Doswell (2002) noted Strong Forcing Derechoes and discrete, significant tornadic supercells (F2-F5) can occur in similar environments.
  • Different types of supercells can be found in the same environment.
  • Thompson and Mead (2006) found in a study of 223 storms over the southern Plains that the probability of significant tornadoes is four times greater with discrete convection over non-discrete.
  • Thompson et al. (2008) found in a study of 359 significant tornado cases that included 864 individual significant tornadoes that the largest tornado outbreaks (events with >6 F2-F5 tornadoes) were dominated by discrete cells, whereas Quasi-Linear Convective Systems produced 33% of singular events.
  • Unfortunately, differences can be very subtle and difficult to diagnose operationally.
what controls storm coverage thompson 2004
What Controls Storm Coverage?(Thompson, 2004)
  • Widespread coverage expected with:
    • Rich moisture influx and steep lapse rates
    • Combination of Q-G and mesoscale ascent
    • (Differential CVA and WAA with surface frontogenesis)
    • Little CIN (Everything goes up.)
  • Isolated (or no) storms with:
    • Marginal moisture and lapse rates (weak CAPE)
    • Neutral to subsident large-scale environment (Rely on small-scale/shallow processes for initiation)
    • Large CIN (Confine storms to “strongly forced” or in areas of most persistent ascent)
    • Bunkers et al. (2006) found in their study of 440 supercells that long lived variety (>4 hrs) tend to occur in medium forced* environments whereas strongly forced events caused more linear or mixed modes of convection.
supercells or squall line
Supercells or Squall Line?

*surface boundaries w/ horizontal temperature gradient of 2.5-5oC/100 km or 300mb jet max of 50-70kts

slide43
Initiating Boundary w.r.t. Deep Layer Flow(Bluestein and Weisman, 2000; Dial and Racy, 2004; James et al., 2005)
  • Parallel: (lines dominate, with end supercells)
  • 45-60o: (discrete supercells, little storm interaction)
  • 90o: (colliding storm splits, but depends on storm spacing and hodograph shape)
progressive trough
Progressive Trough

May 4th 2003 Tornado Outbreak, Progressive Flow Aloft

0-6 km shear across dryline, and storm motion faster than boundary motion

From Rich Thompson, SPC

progressive trough45
Progressive Trough

March 12th 2006 Tornado Outbreak, Progressive Flow Aloft

0-6 km shear across boundary, and storm motion faster than boundary motion

high amplitude trough
High Amplitude Trough

April 6th 2001 Great Plains “High Risk” Squall Line

0-6 km shear largely parallel to

dryline, and storm motion slower than boundary motion

From Rich Thompson, SPC

slide47

Deep Shear vs. Boundary Orientation(March 11-13, 2006)

Sat Eve – 04Z

Sun Aftn – 21Z

Sun Eve – 00Z

Sun Eve – 06Z

derechoes or tornadoes
Derechoes or Tornadoes?

Anvil SR Winds may show some discrimination (Evans 2003).

surface pressure changes
Surface Pressure Changes
  • 1-2 hourly pressure changes help identify:
    • Mesolow /mesohigh couplets and boundaries
    • Concentrated fall/rise couplet enhance low- level convergence/shear by backing surface winds (enhancing tornado threat)
    • Clouds associated with surface pressure falls may be linked to a dynamical feature
    • Implications on thermal advection
    • Rise/Fall couplets may indicate severe wind threat in marginal CAPE environments
tornado parameters
Tornado Parameters
  • Supercell Tornadoes
    • Low Level Shear Vector and Storm Relative Helicity
    • Low Level Thermodynamic Profile
      • Height of LCL
      • Low Level CAPE and CIN
    • Boundaries
  • Non-Supercell Tornadoes
0 1km shear vector
0-1km Shear Vector

Brooks and Craven (2002)

Supercells associated with significant tornadoes

Non-Tornadic

20 kts

15kts

  • Markowski et al (2002) states this is a measure of the amount of horizontal vorticity available near the earth’s surface.
  • The shear magnitude in the lowest 1 km discriminates well between tornadic and non-tornadic supercells, and is a good proxy for 0-1km helicity (Thompson et al, 2002).
  • Does not require knowledge of storm motion.
0 1km shear vector52
0-1km Shear Vector

F4

March 8th, 2009 – 03Z

EF2

March 13th, 2006 – 03Z

EF2

0 1km storm relative helicity
0-1km Storm Relative Helicity

Thompson et al (2002)

Supercells associated with significant tornadoes

Non- Tornadic

0 1km storm relative helicity54
0-1km Storm Relative Helicity
  • SRH can vary up to two orders of magnitude within 100km and 3 hrs.
  • No good threshold, but 100 m2/s2 is considered a good lower number with increasing threat as the numbers grow. Outbreaks 200-300 m2/s2. (Rasmussen and Blanchard, 1998 and Thompson et al, 2002).
  • Esterheld and Giuliano (2008) found in an examination of 65 supercell events that even a smaller depth (10 m – 0.5 km) is a better discriminator of storm classes (i.e. Non Tor. vs. Weak Tor. vs. Sig. Tor) than 10 m – 1000 m.
  • Thompson (2007) found effective SRH discriminated sig-tor better than non-tor cases.
0 1km storm relative helicity55
0-1km Storm Relative Helicity

May 4th, 2003 @ 22Z

April 20th, 2004 @ 23Z

From Banacos (2003)

From Jon Davies Webpage

0 1km storm relative helicity56
0-1km Storm Relative Helicity

March 8th, 2009 @ 16Z

F4

EF2

March 13th, 2006 @ 03Z

EF2

wind shear
Wind Shear

Conway, MO Profiler

slide58

Base Reflectivity – 0040Z

Base Reflectivity - 0142Z

Sunday Evening(March 12-13, 2006)

Base Reflectivity - 0313Z

Base Reflectivity – 0443Z

hodograph kinks
Hodograph Kinks

Four violent tornado events in central and northern Oklahoma have had hodograph kinks. Similar kinks have been observed in MO the fast few years. A pronounced kink with the 1.0-1.5 km AGL layer is where a transition from weak veering, strong speed shear with height to strong veering, weak speed shear.

SGF 5/04/2003-20Z

SGF 3/13/2006-03Z

height of the lcl mean layer
Height of the LCL (Mean Layer)

COMET

  • Markowski (2000) speculates that lower LCL heights (< 1000m) mean high boundary layer RH and increased buoyancy in the RFD.
  • Davies (2006) studied 44 “high” (1,300-2,000m) LCL cases, but they had the other thermodynamic and kinematic factors (including sizeable total and 0-3km CAPE) that are very favorable for supercells.
  • Height of the LCL should be considered a limiting factor instead of an necessary ingredient.
height of the mllcl
Height of the MLLCL

From Thompson et al (2002)

From Brooks and Craven (2002)

let s take a look
Let’s Take a Look

ILX

5/11/2003 @ 00Z

Classic supercells which produced several strong tornadoes.

boundaries
Boundaries
  • Boundaries serve two important functions:
    • Local forcing mechanisms for convective initiation.
    • As a source of vorticity augmentation in mesocyclones.

Boundaries may be difficult to identify.

how important are boundaries
How Important Are Boundaries?
  • Yes!!!:
    • Significant tornadoes usually require higher quantities of SRH than is normally provided. They often require augmentation from boundaries. (Markowski et al (1998a))
  • Maybe?:
    • However, Thompson et al. (2008) found that only 35-40% of their tornado cases (F2-F5) involved a potential storm and surface interaction compared to 70% (F1-F4) during VORTEX-95. In their study of 359 events, boundary interactions were found in a larger percentage of isolated significant tornado cases (46%) vs. during events when there were six or more significant tornadoes (33%)*.
    • Garner (2007) found in a study of 36 events that more long path tornadoes (>25 miles) occurred in environments with no detectable synoptic-scale surface boundary (i.e. fronts) compared to those with shorter paths.

* Percentage is likely lower because multiple tornadoes occurring in close proximity were counted as one case.

forward flank downdraft
Forward Flank Downdraft
  • Streamwise vorticity occurs along the boundaries of the FFD.
  • Parcels generally only acquire 0.001 s–1 shear because of small residence times.
  • For FFD boundaries to be the primary source of streamwise vorticity, it is speculated that the environment must be highly helical (i.e. SRH > 500 m2 s–2 or 0-10 km shear of ~100 kts per Markowski et al (1998b).
outflow from external thunderstorms
Outflow From External Thunderstorms

Rasmussen (2000)

“Cool” side of outflow boundaries:

Look for modified outflow (>6 hrs old) where there’s sunshine and growing CAPE (a.k.a. “cooked” outflow), and surface dewpoints are greater than the warm sector.

boundaries67
Boundaries

Markowski et. al. (1998b)

  • Tornadic development most likely from 10 km on warm side of boundary to 30 km on cool side of boundary.
local example
Local Example

May 6, 2003

local example69
Local Example

Courtesy Fred Glass

April 21, 2002

anvil boundaries
Anvil Boundaries

Preferred direction for longer parcel residence times.

  • Requires limited cloud coverage around periphery of storm.
  • May be more important than the FFD because of much long parcel residence times in the boundary depending on the inflow vector.
significant tornado parameter thompson et al 2004a
Significant Tornado Parameter(Thompson et al, 2004a)
  • The Significant Tornado Parameter is a multi-parameter index. that includes 0-6km shear magnitude, 0-1km storm-relative helicity, surface based CAPE, and surface based parcel LCL height.
      • STP = (sbCAPE/1500 J kg-1) * ((2000-sbLCL)/1500 m) * (SRH1/100 m2 s-2) * (6BWD/20 m s-1) * ((200+sbCIN)/150 J kg-1)
    • When the sbLCL is less than 1000 m AGL, the sbLCL term is set to one.
    • When the sbCIN is greater than -50 J kg-1, the sbCIN term is set to one.
    • The 6BWD term is capped at a value of 1.5, and set to zero when 6BWDis less than 12.5 m s-1.
  • Computed every hour on the SPC Mesoanalysis Page.
non supercell tornadoes
Non-Supercell Tornadoes
  • Typically associated with ordinary cells
  • No CIN
  • Steep low level lapse rates
  • Sharp boundary with low level vertical vorticity.
  • Rapidly developing CBs

Kis et al. (2008) found in numerical modeling experiments that tornadogenesis can occur independently of the mid-level mesocyclone. Low level rotation can occur because of angular momentum transported to near the ground by hydrometers.

non supercell tornadoes74
Non-Supercell Tornadoes

May 25, 1997

From Wakimoto and Wilson (1989)

500mb closed lows
500mb Closed Lows
  • Typically spawn weak tornadoes, but have been associated with F2 damage.
  • Can be overlooked because the environments are usually weakly shear with weak thermodynamics.
  • Tornadoes are often associated with mini–supercells, but can also be non- supercellular because of preexisting vertical vorticity associated with boundaries.

From Davies and Guyer (2004)

wind parameters
Wind Parameters
  • Microbursts
  • Bow Echoes and Derechoes
microbursts
Microbursts
  • Atkins and Wakimoto (1991) found “wet” microbursts occurred on days when the delta theta-e between the surface and mid-levels is >20K. Null days occurred when this value is <13K.
  • Dry microburst tend to occur with high LCLs and steep low level lapse rates.
bow echoes and derechoes
Bow Echoes and Derechoes

Bow echoes and derechoes are associated with moderate to strong shear in the low levels (Przybylinski, 2001). 0-3km bulk shear magnitude determines their potential and attendant severe weather production:

  • <23 kts: Weak Shear (Bow echoes less likely)
  • 22-37 kts: Moderate Shear (Bow echoes likely with the greatest threat for damaging winds/greatest probability for non-supercell tornadoes to occur)
  • >37 kts: Strong Shear (Bow echoes likely with strongest winds remaining above the surface.
slide79

Bow Echoes…Typical Morphologies

Squall Line Bow Echo

(LEWP)

Bow Echo

Supercell

Cell Bow Echo

Bow Echo Complex

Bow Echo

slide81

Forward Prop. Vectors

850mb Theta-e

1000-900mb MLCAPE

1000-900mb MLCIN

July 19, 2006 @21Z

slide82

Forward Prop. Vectors

850mb Theta-e

1000-900mb MLCAPE

1000-900mb MLCIN

July 21, 2006 @ 13Z

elevated hail storms
Elevated Hail Storms
  • Steep mid level lapse rates (850 –500 mb lapse rates 7 deg C/km or greater) above the inversion.
  • MUCAPE > 1000 J/kg
  • Large CAPE in the -10 to -30oC (-20 to -40oC) range on a sounding
  • Strong deep shear (through mean cloud layer wind)
  • Minimized melting effects (lower Freezing levels , WBZ < 10K ft)
surface based storms
Surface Based Storms
  • Mid level updraft rotation (need enough deep shear > 35 kts between 0-6 km AGL)
  • Need steep lapse rates , sufficient low-level moisture, sufficient lifting mechanism (related to CAPE in hail growth zone)
  • Note: in absence of 1., greater dependence on 2.)
supercell hail forecasting
Supercell Hail Forecasting
  • Large CAPE in the layer thatfavors rapid hail growth.
  • 0-6-km shear in excess of 30-40 knots supports supercells with persistent updrafts that contribute to large hail production
  • Lower freezing level heights suggest a greater probability of hail reaching the surface prior to melting
hail forecasting parameters
Hail Forecasting Parameters
  • “Hail Parameters” depicts three forecasting parameters used to predict hail. They are CAPE in the layer from -10 to -30oC, 0-6-km shear vector, and the freezing level height.
  • The Sig. Hail Parameter (SHIP) was developed using a large database of surface-modified, observed severe hail proximity soundings to determine the potential of hail >2" diameter.
    • SHIP = [(MUCAPE j/kg) * (Mixing Ratio of MU PARCEL g/kg) * (700-500mb LAPSE RATE c/km)*(-500mb TEMP C) * (0-6km Shear m/s)] / 44,000,000
  • Both are computed every hour on the SPC Mesoanalysis Page.
summary
Summary
  • Steps for severe weather forecasting:
  • Will I have TSRA? (Moisture, Instability, and Forcing)
  • What will be my primary convective mode and coverage? (Instability, Shear, and Forcing)
  • What kind of severe weather will I have? (Tornadoes, Hail, Winds)
references
References

Atkins, N.T. and R.M. Wakimoto, 1991: Wet Microburst Activity over the Southeastern US: Implications for Forecasting. Wea. Forecasting, 6, 470-482.

COMET Forecaster’s Multimedia Library, 1996: Anticipating convective storm structure and evolution.

Banacos, P.C., 2003: Severe Weather Threat Assessment. Presentation at the, WDTB Severe Weather/Flash Flood Workshop Course 03-4, Boulder, CO.

Bluestein, H.B. and M.L. Weisman, 2000: The interaction of numerically simulated supercells initiated along lines. Mon. Wea. Rev., 128, 3128-3149.

Boustead, J.M. and P.N. Schumacher, 2007: Identification of Inhibiting Factors of a Null Significant Tornado Event. NWA Electronic Journal of Operational Meteorology, 2007-EJ5

Brooks, H. E., and J. P. Craven, 2002: A database of proximity soundings for significant severe thunderstorms, 1957-1993. Preprints, 21st Conference on Severe Local Storms, San Antonio, Texas, American Meteorological Society, 639-642.

references91
References

Bunkers, M. J., et al. 2006: An Observational Examination of Long-Lived upercells. Part I: Characteristics, Evolution and Demise. Wea. Forecasting, 21, 673-688.

Bunkers, M. J., et al. 2006: An Observational Examination of Long-Lived upercells. Part II: Environmental Conditions and Forecasting. Wea. Forecasting, 21, 689-714.

Burgess, D.W., 2003: Supercells. Presentation at the COMAP Course, Boulder, CO.

Burgess, D.W. and L.R. Lemon, 1991: Characteristics of Mesocyclones Detected During a NEXRAD Test. Preprints, 25th Int. Conf. On Radar Meteorology, Paris, France, AMS, 39-42.

Craven, J. P., 2000: A Preliminary Look at Deep Layer Shear and Middle Level Lapse Rates Associated with Major Tornado Outbreaks. Preprints, 20th Conference on SLS, Orlando, FL, AMS, 547-550

Davies, J. L., 2004: Tornadoes in a Deceptively Small CAPE Setting:  The "Surprise" 4/20/04 Outbreak in Illinois and Indianahttp://members.cox.net/jondavies3/042004ilin/042004ilin.htm

references92
References

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