Chapter 11 — WATCH ROUTINES (CONTINUED) 



for a task force or a heavily populated area. 

 It is especially important that the location of 

 the ship be plotted accurately as well as com- 

 plete plotting of the data around the station 

 circle. 



Surface synoptic r sports from ships are 

 identical with land synoptic reports with the 

 exception of the position groups, the direction 

 and velocity of the ship group, the group in 

 which difference between sea water and air 

 temperature is encoded, and the ice group. The 

 ice group is omitted if there is no ice. 



Figure 11-3 shows the grouping entries around 

 the U.S. ship plotting model. 



The first elements to check are the day 

 of the month (YY) and the time (GG), to be 

 sure that the report is consistent with the date- 

 time-group of the chart being plotted. 



Next determine the quadrant of the globe 

 to determine if it will fit on the chart you 

 are plotting. If it fits, then locate the latitude 

 and longitude (L a L a L a , LpLoLoLo). When this 

 position has been located, draw a 3/16-inch 

 circle at this point. The next four groups are 

 plotted in the same manner as the land synoptic 

 code with the exception of the wind group, which 

 must be decoded and plotted according to the 

 wind indicator group (I w ). If this group is a 

 "O" or "1", the wind is in meters and should 

 be doubled before plotting. If it is a "3" or 

 "4", wind is in knots and plotted as reported. 



Refer to figure 11-2 (B) for an illustration 

 of the plotting of a ship's report. 



U. S. Ship Model 



(, 



dd Ch D 8 V S 



TTvmpPP 

 VVww(N)±pp a 



T d T d C, N h W 



(T s T s )h(d w d w P w H w ) 



ASYNOPTIC (OFF-TIME) PLOTTING. — Since 

 a "synoptic chart" is one showing meteorologi- 

 cal conditions observed at various places over 

 a region at or very near the same given Green- 

 wich time, it readily follows that "asynoptic 

 data" are those data not normally appearing 

 on a synoptic chart by virtue of being observed 

 at a different time. In other words, asynoptic 

 data may be termed "off-time" data. Although 

 there is question as to how much difference 

 may exist between observation time and synoptic 

 chart time, and here again local rules have to 

 apply, asynoptic data provide valuable supple- 

 ments to synoptic data in areas where synoptic 

 reporting stations are sparse or in case of 

 communications failure. Frequently, asynoptic 

 reports indicate significant weather developments 

 not apparent at map time. 



The criteria for asynoptic surface data is 

 surface observations more than 1 hour from 

 the synoptic chart time. 



A color code, such as the one given in a 

 previous section of this chapter, should be 

 adopted for plotting such data. These plotted 

 reports must be distinguished from the regular 

 synoptic data because enough changes gener- 

 ally occur during the time intervals to yield 

 an inaccurate or inconsistent analysis if the 

 off- time data were treated as synoptic. 



AIRWAYS CODE PLOTTING. — When bad or 

 hazardous weather is approaching the station, 

 it often becomes necessary to supplement the 

 synoptic map with 3-hourly airways maps. These 

 may be either a regular synoptic type chart 

 or a sectional chart. At times it may even be 

 necessary to enter hourly airways maps. These 

 charts give a detailed analysis over a limited 

 area of the relation of pressure systems, fronts, 

 temperature, and humidity to operationally sig- 

 nificant weather elements. These maps also en- 

 able the forecaster to keep a "weather eye" 

 on the situation and to note any sudden or un- 

 usual changes which are occurring. 



The Airways Code is probably the most 

 familiar of all weather codes. It is used not 

 only when weather reports are made from MF1- 

 10, but can be used to plot airways charts and 

 to fill in areas of sparse or littla data on synoptic 

 charts. 



209.286 

 Figure 11-3.— U.S. ship plotting model. 



Since the airways maps, when plotted, are 

 subject to careful scrutiny, it is imperative 



197 



