AVIATION FORECAST PRODUCT VERIFICATION LEARNING  OBJECTIVES:  Verify   Optimum Path   Aircraft   Routing   System   (OPARS) requests,  Horizontal  Weather  Depictions (HWDs), Airmen’s    Meteorological Information   (AIRMETs)/Significant Meteorological Information (SIGMETs), and Terminal  Aerodrome  Forecasts  (TAFs)  for accuracy. VERIFICATION OF OPARS T h e O P A R S     U s e r ’ s     M a n u a l , FLENUMMETOCCENINST  3710.1,  and  the  AG2 TRAMAN, volume 2, list procedures and the format for OPARS  requests. VERIFICATION OF HWDs Procedures  governing  flight  weather  briefings  and preparing   DD   Form   175-1   and   U.S.   Navy Flight   Forecast   Folders   are   outlined   in NAVMETOCCOMINST  3140.14.  Both  the   AG2 TRAMAN,  volume  2,  and  NAVMETOCCOMINST 3140.14  list  procedures  and  formats  for  the  preparation and  dissemination  of  flight  weather  packets. VERIFICATION OF AIRMETS AND SIGMETS The Airman's  Information  Manual,  Official  Guide to Basic Flight Information, and ATC Procedures briefly discuss  in-flight  weather  advisories  disseminated  by  the National Weather Service (NWS) as well as foreign nations. VERIFICATION OF TAFs Commands   throughout   the   claimancy   having aircraft   on   station   prepare   and   update   TAFs. Information on the TAF code is presented in the  AG2 TRAMAN,   volume   2. NAVMETOCCOMINST 3143.1 promulgates instructions for using the code. As discussed earlier in this chapter, Aerographers should be familiar with the format and encoding of OPARS,  HWDs,  AIRMETs/SIGMETs,  and  TAFs.  But these  products  serve  little  value  unless  there  is  a procedure  in  place  to  verify  them  for  accuracy.  By verifying these products we take into consideration lessons learned when preparing them in the future. The  last  area  discussed  in  this  chapter  covers sources  of  climatic  information. CLIMATOLOGY LEARNING   OBJECTIVES:   Recognize available sources of climatic information for the planning of exercises. In  preparing  for  operations  or  exercises,  the officer-in-tactical command (OTC) and commanding officers  must  be  briefed  regarding  the  climatic conditions expected to occur during the operation or exercise.  Climatology  is  normally  used  for  long  range planning only and should not be used when reliable, real-time  data  becomes  available.  However,  in  certain situations, it maybe  the only forecast data available. For more  information  on  this  subject  refer  to NAVMETOCCOMINST 3140.1. Climatology generally refers to summarizations and/or studies of historical data. Climatology data can be presented in a variety of forms (tabular, graphical, narrative, or analytical charts). When summaries and studies are used for planning, it should be kept in mind that  statistical  averaging  causes  smoothing  of  the observed  data.  Additionally,  the  mean  or  average  of  a given parameter may be a value that is seldom actually observed. Units should review their climatology publications on a routine basis to ensure they have the necessary publications for their area of responsibility (AOR) plus any other areas as may be required during contingency operations. Reference  material,  which  may  be  used  in  the preparation of forecaster’s handbooks and independent studies in the fields of oceanography and meteorology, is available through the Naval Research Laboratory (NRL  Monterey). PUBLICATIONS AND SUMMARIES Existing  climatological  publications  and  summaries can   satisfy   many   requirements.   They   should   be consulted  as  a  primary  source  in  order  to  avoid unnecessary  or  duplicative  data  processing  efforts. Included among these are the following: 10-11