Hi,

I have 2 questions with reference to the Final Tests in the Met. book.


Question No 1

You would expect calm conditions at an aerodrome in the morning to persist for a longer period if:
[a] The synoptic situation indicates the approach of a cold front.
There are signs of build-up of fair weather cumulus.
[c] Skies are overcast with stratus cloud.
[d] Skies are clear and forecast air temperatures are high .


Please explain the reasoning for the answer to be [c].


Question No 9

Refer to the meteorological messages on Page 8.12 of this section.
Depart YSWG 0200 - YSCB - arrive YMER 0350
The forecast wind velocity at 10000 ft between YSCB and YMER is:
[a) 280'T, 30 kts.
280'M, 30 kts.
[c] 340'T,40 kts.
[d] 280'M, 30 kts reducing to zero.

My reasoning is [c] but the answer in the book is [a]


Thank you.

Frederik

In question 1 the other three options all describe situations in which the lower levels of the atmosphere are going to encounter mixing. This will introduce the gradient level wind to the surface, and you would not expect the calm conditions to be lasting. The presence of low level stratiform cloud however, indicates relative stability in the lower level of the atmosphere so mixing is less likely between the gradient level wind and the calm surface. Under these conditions the calm surface wind would be more likely to persist.

As for question 2, I don't have the book in front of me so cannot read the relevant ARFOR. Typically these types of questions involve working out which side of a frontal feature your flight will be conducted so you can select the appropriate winds to use as subdivided in the ARFOR. Have you determined if this is the case for this question?

Thanks Ray. Understood the explanation for the first question. Below is the ARFOR from the book. I believe the trip is east of the east of the trough.

AREA 21 [21]
AMEND AREA FORECAST 090 I 00 TO 091700 AREA 21
OVERVIEW -
SURFACE TROUGH AT 0400 Z: THROUGH YSWG/YMCO
1000Z: YCWR/YMRY
1600Z: EAST OF AREA
SCATTERED SHOWERS AND THUNDERSTORMS. INCLUDING ISOLATED HAIL AREAS OF RAIN
~~~LTRACTING EASTWARDS. ISOLATED FOG AFTER 1600Z, REFER SIGMET RE SQUALLS AND
SUBDIVISIONS -.
A: E OF TROUGH
B: W OF TROUGH
AMDWIND-
2000 5000 7000 10000
A: 350/25 340/30 40/35 340/40
B: 260/25 260/30 260/30 290/30
AMDCLOUD-.
AREAS OF SCT ST 1000/3000 W SLOPES 3000/S000 RANGES
ALSO WITH PRECIPITATION 1000/3000 COAST/SEA .
BKN CUSC 2500/10000 W SLOPES 4500/11000 W RANGES
SCT CUSC 2S00/10000 COAST/SEA 450011 1000 E RANGES
ISOL CB 5000/3S000
BKN ACAS ABV 10000 CONTRACTING E
AMD WEATHERRA
CONTRACTING E SHffS WITH HAIL FOG AFTER 16
VISIBILITY -.
5000M SH/RA 3000 TS
AMD FREEZING LEVEL
A: 12000 B: 9500
AMDICING
MOD IN CU 9500111000 AND AC
AMD TURBULENCE -.
MOD WITH CU AND AC

I agree with you for the second question - arriving at YMER at 0350 will place you just east of the front so the wind at 10,000' will be closer to that described in subdivision A: 340T at 40kts. Doesn't look like a VFR flight though.

Agreed, that looks like an errata. Thanks for bringing it up. The trough first enters the area at 0400 and therefore the flight itself will remain east of it at all times. This would make the conditions in subdivision A applicable where the wind at 10000ft is forecast to be 340^oT at 40kt. I make it answer (c) as well.

Cheers,

Rich