CAPE <300 ------------ Little or No Convective Potential 0300 - 1000 --- Weak Convective Potential 1000 - 2500 --- Moderate Convective Potential 2500 - 3500+ - Strong Convective Potential |
CINH 000 - 020 --- Weak Cap 021 - 050 --- Moderate Cap 051 - 099 --- Strong Cap 100 + -------- Intense Cap |
0
- 6 KM Helicity 150 - 300 ----- Supercells Possible 300 - 400 ----- Supercells Favorable 400 + --------- Tornadoes Possible |
EHI
0 - 6 KM < 1 -------- Supercells Possible 1.0 - 2.0 -- Heightened Tornado Threat 2.0 - 2.4 -- Tornadoes Possible but weak 2.5 - 2.9 -- Tornadoes Likely 3.0 - 3.9 -- Strong Tornadoes Possible 4.0 + ------ Violent Tornadoes Possible |
CAP 000 ---------- No Cap .1 - 1.9 ------ Weak Cap 2 - 4 --------- Moderate Cap > 4 ----------- Strong Cap |
SHOWALTER +3 to +1 ----- Slight % of weak tstorms +1 to -3 ----- Increased % of tstorms -3 to -6 ------ Probable severe tstorms < -6 ---------- Possible Tornadoes |
K <15 ------------ 0% tstorms 15 – 20 ------- 0-20% tstorms 21 – 25 ------- 20-40% tstorms 26 – 30 ------- 40-60% tstorms 31 – 35 ------- 60-80% tstorms 36 – 40 ------- 80-90% tstorms >40 ----------- Near 100% tstorms |
LI +2 to 0 ------- Showers possible 0 to –3 ------- Thunderstorms possible -3 to -6 ------ Severe tstorms possible -6 to –9 ------ Severe tstorms probable -9 & < ------- Air Extremely Unstable |
SWEAT 150 – 300 ----- Slight % severe 300 – 400 ----- Severe possible 400+ ----------- Tornadoes possible |
BRN >45 ---------- Cape > Shear (Pulse) <45 ---------- Supercells possible <10 ---------- Shear > Cape Teens Optimum |
Speed
Shear 0 – 3 -------- Weak updraft potential 4 – 5 -------- Moderate updraft potential 6 – 8 -------- Strong updraft potential 8+ ----------- Severe updraft potential |
Total Totals |
LFC
Heights 0000 - 0499 ------ <1% of tornadoes 0500 - 0999 ------ 35% of tornadoes 1000 - 1499 ------ 28% optimum for F2+ 1500 - 1999 ------ 22% of tornadoes 2000 - 2499 ------ 7% of tornadoes 2500 - 2999 ------ 4% of tornadoes 3000+ ------------ <3% of tornadoes |
LCL
Heights 0500 - 0700 ----- Possible F2+ 0700 - 1000 ----- Possible weak tornado 1000 - 1500 ----- Slight % tornado 1500+ ------------ Unlikely possibility of tornado |
Dewpoints < 55 ---------- Low Moisture Content 55 - 64 ------- Semi - Juicy 65 - 74 ------- Juicy 75> ----------- Incredibly Juicy |
Temperatures 100+ - Incredibly buoyant (if dewpoint greater than 55) 90-99+ - Extremely buoyant (if dewpoint greater than 55) 80 - 89+ - Very buoyant (if dewpoint greater than 55) 70 - 79 - Fairly unstable (if dewpoint greater than 55) 60 - 69 - Marginal (if dewpoint greater than 55) < 60 - Positive temp and dewpoint advection needed |
Low
Level Jet 70> knots ------- Incredibly fast advection 50 to 69 knots -- Very strong low level jet 30 to 49 knots -- Descent low level jet 20 to 29 knots -- Marginal low level jet <20 knots ------- Ill-defined low level jet |
Upper
Jet Winds 200> knots --------- Incredible divergence 150 to 200 knots -- Large divergence 100 to 149 knots -- Good divergence 070 to 099 knots -- Marginal divergence < 70 knots ---------- Small divergence |
Look for Theta-E and Dewpoint ridges, areas with highest Theta-E are areas with highest instability |
Look for areas where the
difference between LCL and LFC is least |
Monitor areas of increasing or substantial moisture convergence, this is typically near area of highest instability and closest to area where storm initiation occurs |
If area had convection earlier be
alert for subtle boundaries that could be focal point for
storms later |
Monitor progress of warm front, cold front, and dryline. Be alert to any bulges as this would be an area of increased convergence and instability |
Watch for area's of backing
surface winds. This is a sign of increased convergence /
instability in the area and an area where storms could be
a bit strong than areas with less or non-backing winds |