Lesson 310 500 hPa Prog Charts

Question 1

When are the 500 hPa charts prepared and transmitted?

Answer 1

Early and complete based on 00 and 12Z data.
Early (vorticity) transmitted 2 hours after observation time.
Complete (thickness) transmitted 3 1/2 hours after observation time

Question 2

Which forecast map covers from the surface to about 24,000’?

Answer 2

Prognostic SFC-400 hPa Sig Wx

Prepared twice daily, valid 00Z and 12Z. Issued approximately 11 hours before it’s valid time.

Question 3

Which forecast map covers from around 10,000’ to 24,000’ and when is it prepared?

Answer 3

Sig Wx prognostic 700-400 hPa.

Prepared 4 times daily based on GFA and transmitted approximately 1 hour after GFA issue.

Question 4

Name the forecast maps made for DND by MSC and are available to Nav Canada and for what periods?

Answer 4

Comox SFC prognostic chart.

Issued for the period of 12, 24, 36 hours.

Question 5

What is the purpose of interpolating?

Answer 5

To determine weather conditions for a location or time at which observations or forecasts are not available.

Question 6

What steps should be taken when discrepancies are noticed?

Answer 6

Identify discrepancies
Determine MANAIR requirements
Apply local procedures

Question 7

How are local effects recognized?

Answer 7

Local effects are recognized when those effects don’t fit the big (synoptic) picture.

Question 8

List the significant factors that can contribute to the formation of local effects:
MSC

Answer 8

Moisture: open water vs. Land, snow/ice cover vs. Bare ground, vegetation vs. soil/Rock
Stability: as above
Circulation: onshore vs. Offshore, upslope vs. Downslope

Question 9

What local effects can happen near bodies of water?

MSTMLCF

Answer 9

Moisture source
Streamers
Thermal low (winter)
Moderated temperature extremes
Land and sea breezes
Convergence zones
Fog/stratus

Question 10

How are local effects recognized?

Answer 10

Local effects are recognized when those effects don’t fit the big (synoptic) picture.

Question 11

List the significant factors that can contribute to the formation of local effects:
MSC

Answer 11

Moisture: open water vs. Land, snow/ice cover vs. Bare ground, vegetation vs. soil/Rock
Stability: as above
Circulation: onshore vs. Offshore, upslope vs. Downslope

Question 12

What local effects can happen near bodies of water?

MSTMLCF

Answer 12

Moisture source
Streamers
Thermal lows (winter)- 
Moderated temperature extremes
Land & sea breezes
Convergence zones
Fog/stratus

Question 13

What local effects can happen near higher terrain?

PPOWW

Answer 13

Persistent radiation fog
Persistent freezing rain
Orographic clouds/weather
Wind: e.g. anabatic/katabatic, valley, Chinook, mountain waves
Windshear

Question 14

What local effects can happen near industry/cities?

Answer 14

Poor visibility

Ice fog

Question 15

Decode the following upper air report codes:

.tb, .ta, .an, .pb, .pa, .up

Answer 15

.tb - sets display mode to significant and mandatory levels
.ta - display mode to mandatory levels and 12 hour changes
.an - display mode to analyzed tephigram data
.pb - display mode to mandatory and significant winds
.pa - display mode to significant winds only
.up - display mode to an upper air table style

Question 16

Define local effect.

Answer 16

Localized weather caused by the interaction between the atmosphere and the earth’s topography.

Question 17

The first things you should check on a map are:

Answer 17

What is it and what time was it or will it be valid.

Question 18

List the steps necessary for interpolating conditions between two reporting points.
RUPT

Answer 18

Recognizing the chart (use the proper chart)
Understanding the plotting model
Proportional distance
Topography/local effects (SFC. Charts only)

Question 19

On a mid-level prognostic chart, forecast of turbulence implies ________ chance of encountering turbulence somewhere within the area.

Answer 19

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