Weather
Understanding Weather - not predicting - 12 April 2013
- Weather
- Published Date
- John Olszewski
- Hits: 86
What happened?
With the double-barrelled impact of global warming and the induced change of climate, much of our conventional knowledge of climate, has been displaced by new patterns. Although the newer range of patterns are similar to historical patterns, they reveal nuances with quite far reaching effects. Exactly what the global and regional dynamics of these variant patterns are, is not yet well-understood by meteorologists.
In other words, synoptics and patterns which have been known to produce identified weather systems can no longer be relied upon to do the same in today’s circumstances. To make it more interesting, what we might build into our knowledge today may not hold good some few years down the line as both the warming and the change factors progress from the current situation.
The analogy with mythical Pandora’s box may not be as far-fetched as we might wish to believe.
A good example is the readiness of anticyclonic cores to proceed along the 40oS track but with varying ability to establish rain-bearing patterns inland and thence across much of Namibia. For much of this new millenium, this ability has held good; but this year this synopsis has seen the upper air core, which feeds the surface cell, dominate the upper air above Namibia: a decided departure from past experience. It must be truly said that one can not be sure whether or not this is a brief irruption or if this is to be part of a future trend.
Read more: Understanding Weather - not predicting - 12 April 2013
Understanding Weather - not predicting - 04 April 2013
- Weather
- Published Date
- John Olszewski
- Hits: 100
What happened?
While the southern hemisphere has experienced astonishing downpours, in Namibia we had good reason to query our prospects.
The desirable weather patterns were on the way though. A sharp cold front extending northward from an intense vortex close the Antarctic shore was advancing east toward the Cape. The upper air trough was just as significant. The significance lay in an obvious clearance of the already weakening middle level anticyclonic core which had taken root across the South-Atlantic for the past dozen or so weeks. Within a couple of days, the southerly airflow was replaced by a developing flow from the northwest bringing with it some moist air throughout its deepening stream of air. Initially, the air-stream was both narrow and limited in its depth. However, the increasing impetus of the circulation provoked by the advancing cold front trough and the tightening isobars proved itself. Within 12 hours the positive development of both convective cumulus cloud and the increasing middle level clouds showing turbulence were visible and active. Shower activity appeared more widespread.
The vortex core was also active. Responding to the thrust of the mobile anticyclone advancing along the 40S range, the frontal push sagged along its northern reach and developed its own closed core vortex: a cut-off low was forming.
Read more: Understanding Weather - not predicting - 04 April 2013
Understanding Weather - not predicting - 28 March 2013
- Weather
- Published Date
- John Olszewski
- Hits: 86
What happened?
These days when weather analysis is to be found at the fingertip through a keyboard, the hard-earned expertise based on observation put together in the ‘dark ages’. comes into its own should the computer models go out of sync. Directly observing changing weather patterns can be very rewarding.
The reluctant skies of the past few months inched toward more purposeful patterns as the new week unfolded. Occasional clouds developed, pushing into the unrelenting dry air aloft.
Something had to give.
Observation showed crisp cumulus heads slowly becoming more numerous and resultant showers that bit more prolific but still short of the required intensity. As the week progressed, other factors, long absent from our skies, loomed.
A return to the fingertip activity confirmed the shift away from the dominant patterns of the past umpteen weeks. The high pressure column now lay eastward and its the controlling grip through the middle layers was fading as two major vortex cores appeared over the southern mid-Atlantic. These carried two extensive troughs northward and, at last, with considerable vertical extent.
Read more: Understanding Weather - not predicting - 28 March 2013
