﻿320 
  0. 
  L. 
  Fassig 
  — 
  March 
  Weather 
  in 
  the 
  United 
  States. 
  

  

  controlling 
  the 
  weather 
  over 
  wide 
  areas. 
  Any 
  marked 
  dis- 
  

   placement 
  of 
  these 
  areas 
  from 
  their 
  normal 
  or 
  average 
  posi- 
  

   tion, 
  or 
  any 
  unusual 
  variation 
  in 
  the 
  intensity 
  of 
  their 
  gradi- 
  

   ents, 
  is 
  associated 
  witli 
  unusual 
  conditions 
  of 
  wind 
  direction, 
  

   temperature, 
  and 
  rainfall 
  in 
  their 
  vicinity. 
  The 
  daily 
  weather 
  

   chart 
  has 
  made 
  us 
  all 
  familiar 
  with 
  the 
  kind 
  of 
  weather 
  asso- 
  

   ciated 
  with 
  the 
  transient 
  areas 
  of 
  high 
  and 
  low 
  pressure 
  which 
  

   pass 
  across 
  the 
  country 
  every 
  few 
  days: 
  with 
  the 
  clear 
  skies 
  

   and 
  light, 
  variable 
  winds 
  of 
  a 
  high 
  area, 
  the 
  rainy 
  unsettled 
  

   weather 
  near 
  the 
  center 
  of 
  low 
  pressure. 
  In 
  interpreting 
  the 
  

   average 
  weather 
  conditions 
  associated 
  with 
  the 
  large 
  persistent 
  

   areas 
  of 
  average 
  high 
  or 
  low 
  pressure 
  we 
  find 
  that 
  the 
  same 
  

   rules 
  apply 
  as 
  in 
  the 
  case 
  of 
  the 
  transient 
  areas 
  based 
  on 
  syn- 
  

   chronous 
  observations. 
  

  

  In 
  view 
  of 
  the 
  slow 
  movements 
  of 
  these 
  areas 
  of 
  high 
  and 
  

   low 
  pressure, 
  their 
  vastly 
  greater 
  extent 
  and 
  greater 
  persist- 
  

   ence, 
  we 
  have, 
  for 
  purposes 
  of 
  weather 
  forecasting, 
  an 
  evident 
  

   advantage 
  over 
  the 
  method 
  of 
  following 
  up 
  the 
  quickly 
  mov- 
  

   ing 
  cyclones 
  and 
  anti-cyclones 
  of 
  smaller 
  extent, 
  which 
  may 
  

   enable 
  us 
  to 
  foresee 
  the 
  general 
  character 
  of 
  the 
  weather, 
  for 
  

   longer 
  periods 
  than 
  we 
  are 
  now 
  able 
  to 
  do. 
  

  

  A 
  better 
  knowledge 
  of 
  the 
  movements 
  of 
  these 
  "great 
  

   centers 
  of 
  action," 
  as 
  M. 
  Teisserenc 
  de 
  Bort 
  calls 
  them, 
  would 
  

   undoubtedly 
  prove 
  a 
  valuable 
  supplement 
  to 
  present 
  methods 
  

   in 
  the 
  practical 
  work 
  of 
  forecasting. 
  For 
  example, 
  should 
  

   further 
  investigation 
  show 
  that, 
  when 
  the 
  pressure 
  in 
  the 
  

   North 
  Atlantic 
  high 
  area 
  is 
  above 
  its 
  normal 
  value, 
  and 
  extends 
  

   farther 
  inland 
  than 
  usual, 
  the 
  paths 
  of 
  all 
  storms, 
  including 
  the 
  

   West 
  Indian 
  hurricanes 
  which 
  may 
  arise 
  during 
  this 
  time, 
  are 
  

   moved 
  westward 
  of 
  their 
  usual 
  paths, 
  we 
  shall 
  be 
  able 
  to 
  deter- 
  

   mine 
  much 
  more 
  accurately 
  the 
  probable 
  paths 
  of 
  our 
  storms. 
  

  

  In 
  any 
  event, 
  since 
  no 
  material 
  improvement 
  has 
  been 
  made 
  

   in 
  late 
  years 
  in 
  either 
  the 
  accuracy 
  or 
  the 
  period 
  of 
  weather 
  

   forecasts, 
  it 
  behooves 
  us 
  to 
  give 
  every 
  encouragement 
  to 
  any 
  

   suggestion 
  which 
  gives 
  reasonable 
  promise 
  of 
  advance, 
  espe- 
  

   cially 
  in 
  the 
  direction 
  of 
  forecasts 
  for 
  a 
  longer 
  period. 
  

  

  In 
  the 
  following 
  pages 
  a 
  brief 
  synopsis 
  of 
  the 
  more 
  

   important 
  researches 
  referred 
  to 
  above 
  is 
  presented 
  in 
  order 
  to 
  

   give 
  a 
  clearer 
  conception 
  of 
  their 
  nature 
  and 
  claims. 
  I 
  have 
  

   attempted 
  to 
  follow 
  a 
  similar 
  method 
  of 
  investigation 
  in 
  a 
  

   detailed 
  study 
  of 
  March 
  weather 
  conditions 
  in 
  the 
  United 
  

   States, 
  with 
  special 
  reference 
  to 
  the 
  Middle 
  Atlantic 
  States. 
  

   An 
  effort 
  is 
  here 
  made 
  to 
  show 
  that 
  the 
  weather 
  east 
  of 
  the 
  

   Kocky 
  Mountains 
  is 
  largely 
  controlled 
  during 
  March 
  in 
  its 
  

   general 
  characteristics 
  by 
  the 
  relative 
  development 
  and 
  the 
  

   relative 
  positions 
  of 
  the 
  persistent 
  areas 
  of 
  high 
  pressure 
  over 
  

   the 
  Atlantic 
  Ocean 
  and 
  over 
  Manitoba 
  in 
  British 
  North 
  

  

  