National Weather Service - Little Rock, Arkansas...Graphical Forecast Help Page

Graphics

Not sure how to interpret the graphics? Look below.

Winds

When you look at the winds in the forecast graphics, you will see numbers and barbs. Here is what they mean.


	The numbers (such as "14" in Figure 1) are wind speeds in knots (x 1.15 equals mph). Barbs are approximations of the numbers. Long barbs are 10 knots and short barbs are 5 knots (a total of 15 knots in Figure 1). The barbs are attached to a line that indicates wind direction (from the northwest in Figure 1 as noted in Figure 2).

In the picture: Figure 1.

In the picture: Figure 2.

Weather

The graphics depicting weather elements will usually have a precipitation type, the probability or expected coverage of the precipitation, and any expected obscurations (such as fog). You may also notice that if there is no weather expected, there will be "<NoWx>" indicated. For more, keep reading...

>>>Coverage/Probability<<<

To right (Figure 3) is a weather graphic showing SChc TRW in the northern part of the Little Rock County Warning Area and Chc TRW elsewhere.
In the picture: Figure 3.

SChc (slight chance) and Chc (chance) are probability terms. They express the likelihood of a certain precipitation type occurring. In this case, the type is TRW...or showers and thunderstorms.

Coverage terms are sometimes used in place of probability terms. For example, Iso (isolated) might replace SChc (slight chance). Also, Sct (scattered) might replace Chc (chance). Below are some common coverage and probability terms...

Coverage	Probability
Isolated (Iso)	Slight Chance (SChc)
Scattered (Sct)	Chance (Chc)
Numerous (Num)	Likely (Lkly)
Widespread (Wide)	Definite (Def)/Occasional (Ocnl)

	The weather graphics (and the terms above) should correlate with the probability of precipitation graphics (like in Figure 4 to left).
In the picture: Figure 4.

Using coverage and probability terms, the percent chances of precipitation should be as follows...

Coverage/Probability % Chance of Pcpn

Iso/SChc 10-20%

Sct/Chc 30-40%

Num/Lkly 60-70%

Wide/Def/Ocnl 80-100%

>>>Types of Weather<<<

TRW (showers and thunderstorms) has already been mentioned as a type of weather. Of course, there are many more. Below is a list of common weather types...


Weather Type	Abbreviation
Thunderstorm	T
Showers	RW
Rain	R
Drizzle	L
Freezing Rain	ZR
Freezing Drizzle	ZL
Snow	S
Snow Showers	SW
Sleet	IP

>>>Intensity/Enhancement Terms<<<

When thunderstorms are in the forecast, you may see the following terms: Dmg W (damaging wind), A (hail), or Hvy Rn (heavy rain). T (thunderstorms) may also be expressed as T+. These enhancement terms are used in times when severe weather or locally heavy rain/flash flooding are possible. Other intensity terms are used to express the character of expected precipitation...

Intensity	Meaning
-- (double minus sign)	very light (used with drizzle/flurries)
- (minus sign)	light
+ (plus sign)	heavy

>>>Obscurations<<<

Finally, you may notice an obscuration in the forecast from time to time. Obscurations such as fog occur...mainly during the morning hours. Below is how fog and other common obscurations are expressed.

Obscuration	Abbreviation
Fog	F
Haze	H
Freezing Fog	ZF

As was the case with precipitation, obscurations can also have character. For example, fog can develop in "Areas" or may be "Patchy". It can also be dense (expressed with a "+" such as "Areas F+") on occasion.

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