“—
:
~
lowes
rein shoners”end. thundérstorns » is the exclusive cause of the solngbsBi
lities,
The durationof the ‘showers {and the low visibilities) is generally 30 minutes
or less,
~~
1?
5, CLOUDS:
. Be at 0630 locel time cn evon chance exists tht the total sky covercge
(all clouds considered - low, middle, ond high) will be 7/10 or more, But over-
east, (10/20 coverage) conditions my be ox-ected only cbout 20% of the timo,
There is a slight tendency for overall cloudiness to increase cs,*the secson propresses, clso for a daily mximum of cloudiness to occur nocr.-suhrise,
b, About 75% of the time the “trade” cumlus, normlly' based et 1800
to 2000 fcet with tops ct 8000 to 10000 fcet, will cover 2/10 to4/10 of the sky.
The middlc clouds (10000 to 25000 fcot) villbe essocinted with the eddies previously mentioed, at times these clouds my become very axtensive, very thick,
end remark:bly persistent, Cirrus clouds cre commonly present, | Difficulties in
precisely observing ond measuring these translucent, hozy typo clouds mke a
i
complete analysis of present dete on cirrus of dubious velue,
:
6,
i
WINDS:
?
t
i
a, 4&t the surfsce the persistent trado winds blou from the ENE to NE
at 10 to 20 knots. Although such persistence in direction end speed is not
found <loft, cbove 25000 to 30000 feet westerly winds sre obsorvecd about 65%
of the time, The frequency of occurrence of the westorlics ebove 25000 fect
increases 2s the season progresses,
The height st “hich the vesterlies first
eppecr hes < wide range, The prediction of this height is one of the most com
- plex forecasting problems,
i
b,
at ENI ETO, G0. of the time ‘rind spacds at ong Level up to 50000
feet may be expected to be 30 imots or less, an cntlysis was mde of 617 individu:l rewin ascents thich resultcd in 2456 soperate observ: tions as folloms:
617 at 10000 feet; 591 ct 16000 feet; 535 = 26000 Feet; 475 at 33000 fect; and
238 =t 49000 fect. The cnclysis showed only one occurrence of 2
2 wind speed
‘greater than 58 knots, Howcver, in the sre: te the erst of ENT RTOY, the frequency of strong west winds incrocses considercbly. For ox-cmple3 during Oper—
rtion SANDSTQVE (UNCLASSIFIED) the freguoncy of rinds above 50 knots in the
RONGERIK arec wos observed to be 154, at the s-me timo the frequency of 50
knot winds increcsed to the north ond east to as mich 2s 553 at LabE, It is
believed thst the SaNDSTGE (UNCLASSIFIED) period represented < Levee devisti on
from conditions thich are norm-lly prev~lent.
7. TROPOPAUSE:
a,
The tropopruse is the transition zone betwecn the troposphere cnd
the stratosphere.
It is most frequently found bet~ecn 54000 and 60000 fect
above the Earshells, The tempercture of the tropooruse in this nres 7111 be
-75 to -80 degrees Contigr-de with warmer temperatures «bove snd below the
_tropopause,
45000 feot.
8,
‘Temperatures nor ~55 degrees Contigr-dc should be axpectcd 7t
TYFHOCHS:
2.
The months Jsnucry through april cxericnec «= minimum of typhoon
cetivity in the Southrest Freific area, Usuclly cbout tro typhoons occur during
this four month period, Thc ch-nce is remote, however, that ExTWkIOk will be
dircetly effected, The Tesk Force eather Central xnd the Verther Reconnczissance
Elomcnt till work closoly ~rith the Typhoon Verning Contcr snd the 54th Strategic
Reconnaissance Squ-dron Cieather) -t Gum to detect ond loc-te all suspected or
actucl typhoons vhich might cffeet the Mersholl Isl-nd crez.
aspproprinte ad-
TaSK GROUF 7.4
OFRS ORDER HO, 1-53
AIVEX BE, arNDx 3
shed
acopia S200.
visérics ond wornings will be issucd to 2ll units ~hen these destructive ‘storms
might affcet Task Foreo activitics.
oot p B32