Waardes severe weather en tornado's
Waardes voor severe weather en tornado's
| Gewijzigd: 6 april 2013, 15:10 uur, door Ries
| Total totals | |
| <44 | Convection not likely |
| 44-50 | Likely thunderstorms |
| 51-52 | Isolated severe storms |
| 53-56 | Widely scatterd storms |
| >56 | Scattered severe storms |
| Speed shear | |
| 0-3 | weak |
| 4-5 | Moderate |
| 6-8 | Large |
| 8+ | Severe |
| K index | |
| 15-25 | Small convective potential |
| 26-39 | Moderate convective potential |
| 40+ | High convective potential |
| Cape | |
| 1-1.500 | Positive |
| 1.500 - 2.500 | Large |
| 2.500+ | Extreme |
| Sweat | |
| 150-300 | Slight severe |
| 300-400 | Severe possible |
| 400+ | Tornadic possible |
| SR Helicity | |
| 150-300 | Possible supercell |
| 300-400 | Supercells favorable |
| 400+ | Tornadic possible |
| Lifted Index/ SWI | |
| -1 to -4 | Marginal instability |
| -4 to -7 | Large instability |
| -8 or less | Extreme instability |
| BRN | |
| <45 | Supercells favorable |
| <10 | Too sheared |
| Teens | Optimum |
| EHI | |
| EHI >1 | Supercells likely |
| 1 to 5 | EF2, EF3 tornadoes possible |
| 5+ | EF4, EF5 tornadoes possible |
| Minimum bulk shear 500MB for supercells |
| 30 to 40 kts |
| Gewijzigd: 6 april 2013, 15:10 uur, door Ries
Freedom is not worth having if it does not include the freedom to make mistakes.
Notes severe weather en tornado's
- Max uvv = square root of 2 × CAPE
- BRN (Bulk Richardson Number) = CAPE / (0-6 km) Shear (500MB)
- Showalter (SWI) = used when elevated convection is most likely (cool season)
- EHI = (SR HEL × CAPE) /160,000
- SWEAT = 12(850Td) +20(TT-49) +2(V850) + (V500) +125(sin(dd500-dd850) + 0.2)
- Total Totals = (T850- T500) + (Td850 - T500)= vertical totals plus cross totals
- K index = (T850 -T500) + (Td850 - Tdd700)
- SR Helicity : determines amount of horizontal streamwise vorticity available for storm ingestion
- streamwise = parallel to storm inflow
- Important to look for thermal and dewpoint ridges (THETA-E)
- For tornado, inflow must be greater than 20 knots
- 20 to 30% of mesocyclones produce tornadoes
- Tornado types: rope, needle, tube, wedge
- Look for differential advection; warm/ moist at surface, dry air in mid levels
- Severe weather hodograph: veering, strong sfc to 850 directional shear
- >100 J/kg negative buoyancy is significant
- Good match: BRN < 20 and CAPE >2,000 J/kg
- Strong cap when > 2 degrees Celsius
- Study depth of moisture, TT unreasonable when low level moisture is lacking
- KI used for heavy convective rain, values vary with location/season
- Instability enhanced by ... daytime heating, outflow boundaries
- Models generally have weak handle on return flow from Gulf, low level jet, convective rainfall, orography, mesoscale boundaries, and boundary conditions
- Large hail when freezing level >675 mb, high CAPE, supercell
- Synoptic scale uplift from either surface WAA or upper level divergence
- Fair weather cumulus: cumulus humulus, cumulus mediocrus
- T-storm warning when Hail > 3/4", wind > 58 mph, gate to gate shear > 90 knots
- Sounding types: Inverted V, goal post, Type C, wet microburst
Freedom is not worth having if it does not include the freedom to make mistakes.
| 8+ | Very high probability of a tornado |
| 6 | High probability of a tornado |
| 4 | Moderate chance of a tornado nearby, but hail and/or high wind gusts possible |
| 2 | Low chance of a tornado, but hail and/or high wind gusts possible |
| 0 | Near-zero chance of a tornado or a severe thunderstorm |
De uitleg
Bron: The Weather Channel | Gewijzigd: 17 april 2013, 19:01 uur, door Marga
Every cloud has a silver lining
