Northern Alabama - Decatur - Priceville
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Daily Weather Charts
Office, National Weather
Storm Prediction Center, NCEP, NWS
Weather Station at 24 Willow Place:
KALDECAT4 | CW7715 | PWS Weather
Weather Station at Pryor Field, Decatur, AL - Conditions - Last Three Days | Meteogram
Station KEET in Birmingham, AL
Sounding for Decatur, AL
Questions concerning values displayed on the SKEW-T graphic that expand understanding of the stability of the air mass over this area, together with its potential for severe weather:
Sounding variables and indices
/ N -
L57 Lapse Rate: Greater than 5.5°
greater than 6.7°
Y / N - Is the Theta-E Index greater than 5? Greater than 8?
Y / N - Lifted Index (LI): Less than -4? Less than -8?
Y / N - Showalter Index (SI): Less than -4? Less than -8?
Y / N - Total Totals Index (TT): Greater than 53? Greater than 56?
Y / N - K Index (KI): Greater than 26? Greater than 40?
Y / N - SWEAT Index (Severe Weather Threat Index): Greater than 300? Greater than 400?
Y / N - Energy Index (EI): Less than 0? Less than -2?
/ N -
CAPE ( Convective available potential energy): Greater than 1,500?
Greater than 2,500?
Y / N - CINH (Convective inhibition): Greater than 51? Greater than 200?
Y / N - CAP: (Cap strength): Greater than 2.0? Greater than 4.1?
Y / N - Super-adiabatic lapse rate – where the temperature decreases with height – at a rate of greater than 10 degrees Celsius per kilometer? (data is displayed on the NWS Skew-T Sounding Charts in the lower left corner)
/ N - HEL (Storm
relative helicity): Greater than 300? Greater than 400?
Y / N - EHI (Energy-Helicity Index): Greater than 1? Greater than 5?
Y / N - BRN (Bulk Richardson Number): Less than 45? In the teens?
Y / N - Upper level winds (between 500 and 300 mb level) of greater than 100 knots?
Y / N - Low level winds (850 to 700 mb) at 25 knots or greater?
Y / N - Atmospheric winds increasing at higher levels (upper level speed shear greater than 70 knots)?
Y / N - Atmospheric winds from different directions (directional shear of 60 degrees or more from the surface to 700 mb)?
Current Surface Conditions
/ N - Dew Point greater
than 55 degrees?
Y / N - Temperature greater than 80 degrees? In the forecast? - Y / N (High temperature and high dew point indicates high instability, increasing the threat of severe weather.)
Y / N - Relative Humidity (RH): Greater than 50%? Greater than 80%?
Y / N - Is there a 30 to 50 degree surface temperature/dew point spreads? (High microburst potential.)
When these values indicate the potential for severe weather, or where there is some questions about the values displayed on the graphic, I bring up the Text version of the SKEW-T and check the appropriate values.
PW - Moisture Content:
0.50 inches or less = Very low
Greater than 75° = Very high
65-74° = High
55-64° = Moderate
Less than 55° = Low
Low Level Jet
Greater than 70 knots = Extremely high
50-69 = Very high
30-49 = High
20-29 = Moderate
Less than 20 = Low
Additional Variables to Watch: Vertical Wind Shear, Veering, Mid-level Cap, Helicity.
See also SKEW-T for Birmingham, AL.
See generally "Getting to Know the SKEW-T Parameters" by meteorologist Jeff Haby.
Current Weather in Priceville, AL (Cumulus)
KALDECAT4 | CW7715 | PWS Weather
Pryor Field, Decatur, AL - Current Conditions | Meteogram | Text Archive
Southeast Sector - Storm Prediction Center Mesoanalysis Sectors
National Weather Hazards
Graphical Weather Forecasts from the Huntsville Weather Forecast Office
Day One Convective Outlook
National Weather Service
A few of the additional weather pages on this web site:
Daily Weather Charts - Complete
Huntsville Weather Forecast Office, National Weather Service
Short Term Forecast
(The 6-Hour NOWCAST).
Not issued during fair weather. Access only during inclement weather; carefully check the date and time.
Special Weather Statements
Issued infrequently; carefully check the date and time.
Storm specific; carefully check the date and time.
Storm Prediction Center: Watches, Mesoscale Discussions, Outlooks