Decoding Guide

Freezing Level Analysis


The Freezing Level Analysis depicts freezing level at individual stations, as well as general contours.


0000 and 1200 UTC

Data Sources:

Upper air analysis


Solid white lines are contours of the lowest freezing level and are drawn for 4,000 foot intervals and labeled in hundreds of feet MSL. When a station reports more than one crossing of the 32 degree isotherm, the lowest crossing is used in the analysis. A dashed line represents the 32 degree isotherm at the surface and will outline an area of stations reports "BF" (below freezing).


Freezing levels for individual stations are depicted in green. The following examples show how to decode the observations.


Plotted Interpretation
Freeze Entire observation is below freezing
Freeze Freezing Level is at 2,800 feet; Temperatures below freezing above 2,800 feet.
Freeze Freezing level at 12,000 feet; Temperatures above 12,000 feet are below freezing.
Freeze Temperatures are below freezing from the surface to 5,100 feet; above freezing from 5,100 to 11,000 feet and below freezing above 11,000 feet.
Freeze Lowest freezing level is at 300 feet; below freezing from 300 feet to 3,400 feet; above freezing from 3,400 to 9,000 feet and below freezing above 9,000 feet. (See illustration below)
Freeze Data is missing.
Plotted Value Interpretation
Freeze Freeze