. All factors point toward weakening of the
system.
7. Sketch the preliminary contours, connecting the
forecast positions of the long waves, short waves, and
the pressure systems with the values determined by
steps 1 through 5 above.
8. The last step in the construction of a constant
pressure prognostic chart is to check the chart for the
following points:
. The chart should follow continuity from the
existing pattern.
. The chart should be vertically consistent and
rational in the horizontal.
. The chart should not deviate from the seasonal
pattern unless substantiated beyond a doubt.
. Unless indicators dictate otherwise, it should
follow the normal patterns.
Now draw the smooth contours, troughs, ridges,
highs, and lows; and adjust the gradients.
Application of Satellite Imagery
Satellite imagery provides the forecaster with
information that may be used in conjunction with
previously discussed techniques in forecasting
movement and intensity of troughs, ridges, and systems
aloft. As discussed in the AG2 TRAMAN, volume 1,
satellite imagery should be compared with the analyzed
charts and products to ensure they reflect a true picture
of the atmosphere.
As with the analyses, satellite
imagery should also be used in preparation of your
forecast products.
The following features can be useful to the
forecaster in producing prognostic upper-air charts:
. Positive vorticity advection maximum (PVA
maximum) cloud patterns associated with the upper-air
troughs and ridges
l Cloud patters indicative of the wind flow aloft
Computer Products
Upper-level prognostic charts with varying valid
times are uploaded to the Naval Oceanographic and
Data Distribution System (NODDS) daily. Items
included on the charts will vary on an individual basis,
with respect to the contours for the particular height,
isotachs, and isotherms.
The forecaster may use these charts directly for
preparing forecasts, or in conjunction with their own
prepared products.
A complete listing of charts
available with descriptions is found in the Navy
Oceanographic Data Distribution System Products
Manual, FLENUMMETOCCENINST 3147.1.
The Fleet Numerical Meteorology and
Oceanography Center prepares a large number
of computer products for upper air forecasting. The
Numerical Environmental Products Manual,
v o l u m e 3 ( E n v i r o n m e n t a l P r o d u c t s ) ,
FLENUMMETOCCENINST 3145.2, lists available
products.
SUMMARY
In this chapter we first discussed general prognostic
considerations. The value of an accurate, hand drawn
analysis was addressed, along with a discussion of
available aids, including computer products and satellite
imagery. The majority of this chapter deals with
objective forecasting techniques used in the preparation
of upper level charts. The first topic discussed was that
of forecasting the movement of troughs and ridges,
followed by a discussion on forecasting the intensity of
troughs and ridges.
Lastly, forecasting of the
movement, intensity, and the formation of upper level
systems and associated features were covered.
2-10
