Most forecasters know that while the LFM and the NGM forecast data bulletins are very helpful aids in producing a forecast for their station, they do not contain all of the necessary information. Therefore, LFM Model Output Statistics (MOS) bulletins, which compare the current synoptic situation with the climatological records and past weather occurrences, should also be used. Probability forecasts for many stations are available in the MOS bulletins. Table 4-3-8 lists the available MOS bulletins by region.  

Table 4-3-8.-MOS Forecast Regions, Subregions, and Stations Available

From the number of stations available, you can see that just about any location in the United States that you would need to forecast for is covered by a MOS bulletin. The NMC computers take the same raw data that goes into these MOS bulletins to make computer-worded, plain-language forecasts for many of these locations. These are the forecasts were sure you have seen on television weather programs like The Weather Channel , or heard over the radio. We will not cover these types of forecasts, although they are available as bulletins, but we will cover the types of information available in the MOS bulletins.

Table 4-3-9 shows a typical section of a MOS bulletin showing the data format for one station.

Line 1 is the MANOP header. Line 2 is the product identification, or heading line, which contains the date and time in GMT of the data cycle the product was produced from. Line 3, which begins with DY/HR, contains the forecast date (DY) and time (HR) in GMT that each forecast column is valid. These three lines appear only at the beginning of each bulletin. Each stations data begins with a line contain- ing only that stations three-letter identifier. This is line 4. In our example, the station is NPA, for NAS Pensacola, Florida. Lines 5 through 20 contain the actual forecast data. We will use the 06/00 forecast, or the forecast for 0000Z 6 December 1989, as our examples to clarify each point:

POP06 is the probability of precipitation during the 6-hour period ending at the forecast time. In our example, 5 is 5 percent chance of precipitation.

POP12 is the probability of precipitation during the 12-hour period ending at the forecast time. Probabilities are to the nearest percent. 10 is a 10 percent chance of precipitation.  

QPF06 is the Quantitative Precipitation Forecast probability for the 6-hour period ending at the forecast time. More simply, this is a probability of the total accumulated precipitation during the period falling into the ranges listed below. All probabilities are in tens of percent. (A 7 would mean 70 percent.) The format is ABC/D. than 1.00 inch. C is the probability of receiving occurrence), where the categories are 1, less than 000/1 means that we have 00 percent chance of period in category A, B, or C and that if any inch (category 1).

QPF12 is the Qualitative Precipitation Forecast for the 12-hour period ending at the forecast time. Again, probabilities are in tens of percent. The format is ABCD/E. A, B, and C are 4 is 1.00 to 1.99 inches; and 5 is 2.00 inches or in categories A, B, C, or D and that if any inch.

TSTM is the probability of receiving a radar echo from a precipitation area of level 3 (VIP 3) or stronger (which would imply thunderstorm activity) from within the stations 20-mile-square radar coverage reporting block (MDR block), during the 12-hour period ending at the forecast time. Basically, this is the probability of having a thunderstorm within 10 miles of your station. Probabilities are to the nearest percent. 1 means there is a 1 percent 0000Z 6 December.

POPT is the probability of precipitation type. All probabilities are to the nearest percent. The format is AABB/C. AA is the probability of means that we have a 1 percent chance of freezing rain but that the best category is 3, rain or mixed precipitation.

POSA is the probability of snow amount for the 12-hour period ending at the 24-hour forecast time. The entire string of 13 digits and 3 solidi are for the single 12-hour period. All 9s indicate no snow is forecast. The forecast uses two different types of probabilities and is presented in the format AABB/CCDD/EEFF/G.  

G is the MOS categorical forecast for snow amount. The four categories are 0, 2, 4, and 6, where 0 is <1 inch, 2 is 2 to 3 inches, 4 is 4 to  

The example 9999/9999/9999/0 indicates that no snow is forecast. If the POSA were 0902/0300/0000/0, it would mean a 9% chance of > 2 inches and a 3% of > 4 inches of snow between 05/0000Z and 05/1200Z if it snows, but only a 2% chance of any snow. MOS forecasts 0, less than 1 inch of snow.

MN/MX is the minimum or maximum temperature forecast, in degrees Fahrenheit, that may occur at any time during the 12-hour period ending at the forecast time. 66F is the maximum temperature forecast between 05/1200Z and 06/0000Z.

TEMP is the actual temperature forecast, in degrees Fahrenheit, in 3-hour increments; the first temperature is for the forecast time, while the second is 3 hours later. 57 53 in the 06/00 06/0000Z is 57F, while the temperature 3 hours later, at 06/0300Z, should be 53F.  

DEWPT is the dew-point temperature forecast in 3-hour increments (same as the temperature). 46 45 means the dew point at  

WIND is the surface wind forecast at the forecast time in the format DDFF.DD is the wind direction, in tens of degrees, and FF is the wind speed, in whole knots. 2606 means the wind will be from 260 true at 06 knots at 06/0000Z

CLDS is the forecast for the total cloud amount probability at the forecast time. These probabilities are in tens of percent, and are presented in the format ABCD/E. A is the is overcast clouds (10/10 coverage). 4322/2 means or overcast conditions; MOS forecasts 2, scattered clouds at 06/0000Z.

CIG is the ceiling height probability forecast at the forecast time. Probabilities are in tens of percent and in the format ABCDEF. A is the probability of a ceiling <200 feet. B is the a 70% chance of a >7,500-foot ceiling.

VIS is the probability forecast of a range of visibilities in statute miles at the forecast time. Probabilities are in tens of percent and are in the format ABCDEF. A is the probability of and a 90% chance of >6-mile visibility.

C/V is the MOS categorical forecast for ceiling height (C) and visibility (V). Forecasts are given as a number from 1 to 6 in each category. The number 1 is A; 2 is B; 3 is C; 4 is D; 5 is E; and 6 is F in their respective groups given above. 6/6 means MOS forecasts the ceiling to be >7,500 time.

OBVIS is the probability of obstructions to vision, in tens of percent, in the format ABCD/E. A is the probability of no obstruction. B is the probability of haze or smoke. C is the The MOS forecasts 1no obstructions to vision.

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