Nov 292013
 

An upper cold front has passed across Tasmania overnight, rapidly moving over the Tasman Sea towards New Zealand today.  A broad tropopause ‘curtain’ fold, dramatically illustrating the front, hangs over the Tasman Sea in the 28-11-2013-18z, WeatherTheatre SceneOne Australia snapshots. The heaped up Theta surface below shows the extent of the associated cold air.

WeatherTheatre SceneOne 28-11-2013-18z Snapshot

WeatherTheatre SceneOne 28-11-2013-18z Westerly Perspective Snapshot. A heaped-up Theta (lower surface) mound illustrates the extent of the cold air associated with the upper cold front, identified by the tropopause curtain situated immediately above. Red shadings correlate with the strongest winds (upper surface) and warmest temperatures (lower surface). Conversely, blue shadings correlate with the weakest winds (upper surface) and coldest temperatures (lower surface).

WeatherTheatre SceneOne 28-11-2013-18z Snapshot

WeatherTheatre SceneOne 28-11-2013-18z Top-down Perspective Snapshot. The valley in the tropopause marks an upper cold front crossing the Tasman Sea. Red shadings correlate with the strongest winds. Conversely, blue shadings correlate with the weakest winds.

WeatherTheatre SceneOne 28-11-2013-18z Snapshot

WeatherTheatre SceneOne 28-11-2013-18z Southeasterly Perspective Snapshot. The curtain appearance of the tropopause (upper surface) in the background signifies an upper cold front crossing the Tasman Sea. Red shadings correlate with the strongest winds (upper surface) and warmest temperatures (lower surface). Conversely, blue shadings correlate with the weakest winds (upper surface) and coldest temperatures (lower surface).

Nov 282013
 

A vigorous, early-winter season cold front has lead to the rapid development of a deep surface low over the northeast USA, bringing widespread snowfalls.  The front features prominently on 27-11-2013-18z, WeatherTheatre snapshots.  The Top-down Perspective of the tropopause shows a large amplitude, positively tilted, shortwave disturbance on the right side.  A distinctive and dramatic double-fold tropopause ‘curtain’ is apparent on the Northerly Perspective, as the subtropical jet begins to merge with the polar jet at the jetstreak entrance region.  Meanwhile, deep-blue shadings in the background are a very much elevated 300K Theta surface associated with very cold air.

WeatherTheatre 27-11-2013-18z Northerly Perspective Snapshot.

WeatherTheatre 27-11-2013-18z Northerly Perspective Snapshot. A ‘curtain’ tropopause displays twin folds, more distinctive in the foreground, where jetstreams merge.  Red shadings correlate with the strongest winds (upper surface) and warmest temperatures (lower surface). Conversely, blue shadings correlate with the weakest winds (upper surface) and coldest temperatures (lower surface).

WeatherTheatre 27-11-2013-18z Top-down Snapshot.

WeatherTheatre 27-11-2013-18z Top-down Snapshot.  The large amplitude, shortwave disturbance features prominently on the right, where its associated jetstreak stands out in the red shading.  Red shadings correlate with the strongest winds (upper surface) and warmest temperatures (lower surface). Conversely, blue shadings correlate with the weakest winds (upper surface) and coldest temperatures (lower surface).

Nov 282013
 

A strong upper front is nearing Tasmania and features prominently in the 27-11-2013-18z, WeatherTheatre Analysis, snapshot.  The front is made apparent by a deeply folded tropopause (upper surface), seen in the background of the Southeasterly Perspective below.  As a result, rapid cyclogensis is occurring with a surface low quickly deepening.  Most forecast models show the low situated east of Tasmania by Thursday night.

WeatherTheatre 27-11-2013-18z Snapshot

WeatherTheatre 27-11-2013-00z Southeasterly Perspective, showing a strong front near Tasmania, apparent by the folded tropopause (upper surface) and consequently raised Theta (lower) surface, indicating cold air. An upper trough over Western Australia can be seen as a slender vorticity tube, suspended from the surface above, in the right foreground.  Thin cyclonic-vorticity filaments, suspended in the foreground are due to Ex-Tropical Cyclone Alessia.  Red shadings correlate with the strongest winds (upper surface) and warmest temperatures (lower surface). Conversely, blue shadings correlate with the weakest winds (upper surface) and coldest temperatures (lower surface).

A small upper trough over Western Australia, marked by a tropopause vorticity-tube extending down from the surrounding tropopause surface above, can be seen in the right of the snapshot.

Thin filaments of cyclonic-vorticity, visible in the foreground, are due to a Ex-Tropical Cyclone Alessia which is located over the Gulf Country.

Nov 272013
 

The WeatherTheatre, 27-11-2013-0z, North American Analysis shows a strong upper front crossing the Northeastern USA, which is driving rapid cyclogenesis and the formation of a deep surface low. The Northwesterly Perspective shows the eastern side of a deep tropopause fold (upper surface), oriented from the southwest to the northeast.  Comparison between the Northeasterly and Northwesterly Perspectives reveals the elongated nature of the front which runs across the eastern USA from the southwest to the northeast.  The raised Theta surface below indicates the spread of the associated cold air.

WeatherTheatre 27-11-2013-00z Snapshot

WeatherTheatre USA, 27-11-2013-00z, Northwesterly Perspective.  The poleward, northeasterly orientation of a strong upper front and tropopause fold (upper surface) across the eastern USA is apparent. Red shadings correlate with the strongest winds (upper surface) and warmest temperatures (lower surface). Conversely, blue shadings correlate with the weakest winds (upper surface) and coldest temperatures (lower surface).

WeatherTheatre 27-11-2013-00z Snapshot

WeatherTheatre 27-11-2013-00z USA Northeasterly Perspective. A strong upper front and deep tropopause fold (upper surface) dominates the centre foreground. Red shadings correlate with the strongest winds (upper surface) and warmest temperatures (lower surface). Conversely, blue shadings correlate with the weakest winds (upper surface) and coldest temperatures (lower surface).

Nov 272013
 

The WeatherTheatre, 26-11-2013-12z, Australia, Analysis snapshots feature a strong upper front over the Tasman Sea, where the sub-tropical and polar jetstreams are merging.  Darker shadings on the top-down perspective show the steepness of the tropopause in this region, which is prominent in the upper left of the south-easterly perspective snapshot. A tiered, folding, tropopause surface indicates the merging jetstreams in the frontal region. The polar jet is associated with the lower tier and the subtropical jet the higher tier.

WeatherTheatre 26-11-2013-12z Snapshot

WeatherTheatre 26-11-2013-12z top-down snapshot.  A strong upper front over the Tasman features prominently in the darker red shadings at the right of the image.  A weakening upper trough over central Australia, apparent by the tunnel in the surface, is near the centre.  On the far left, another upper trough, apparent by another tunnel in the surface, is entering the scene.  A strong upper front, well south of the continent, is visible in the red shadings near the bottom left. Red shadings correlate with the strongest winds (upper surface) and warmest temperatures (lower surface). Conversely, blue shadings correlate with the weakest winds (upper surface) and coldest temperatures (lower surface).

 

 

A weakening upper trough, which has been supporting a surface low over Western Australia, appears near the centre of the top-down perspective as a tunnel in the tropopause surface. Another upper trough can be seen to its west and will effect Western Australia over the next 24 hours.

 

A strong upper front in the polar jet, situated well south of the continent, appears in the right background of the south-easterly perspective snapshot. This is one to watch over the next 24-48 hours as it should cause the formation of a deep surface low east of Tasmania on Thursday evening.

WeatherTheatre 26-11-2013-12z Snapshot

WeatherTheatre 26-11-2013-12z South-easterly Snapshot.  The strong upper front over the Tasman Sea features prominently as the deep fold of the tropopause (upper sruface) in the left of the image.  An upper trough over central Australia shows up near the centre foreground.  A strong upper front well south of the continent is seen by the lowering in the right background.  Red shadings correlate with the strongest winds (upper surface) and warmest temperatures (lower surface). Conversely, blue shadings correlate with the weakest winds (upper surface) and coldest temperatures (lower surface).

Nov 262013
 
WeatherTheatre 25-11-2013-18z Snapshot

WeatherTheatre 25-11-2013-18z snapshot, south-westerly perspective.  A disturbance in sub-tropical jet over Western Australia is visible in the upper right foreground (upper surface) and a mid-latitude disturbance behind it.  Red shadings correlate with the strong winds (upper surface and vectors) and warmest temperatures (lower surface).  Conversely, blue shadings correlate with the weakest winds (upper surface and vectors) and coldest temperatures (lower surface).

WeatherTheatre 25-11-2013-18z Snapshot
WeatherTheatre 25-11-2013-18z snapshot, easterly perspective. The tropopause front over Western Australia is seen in the mid-foreground (upper surface), while the mid-latitude front is seen on the far right. A disturbance persisting over the Tasman Sea is visible in the background.  Red shadings correlate with the strongest winds (upper surface and vectors) and warmest temperatures (lower surface).  Conversely, blue shadings correlate with the weakest winds (upper surface and vectors) and cold temperatures (lower surface).

WeatherTheatre 25-11-2013-18z Snapshot
WeatherTheatre 25-11-2013-18z snapshot, south-easterly perspective. The disturbance over the Tasman Sea features prominently. Tiered tropopause (upper surface) folding is occurring as the polar jet merges with the sub-tropical jet, creating a stepped appearance to the tropopause.  Red shadings correlate with the strongest winds (upper surface and vectors) and warmest temperatures (lower surface).  Conversely, blue shadings correlate with the weakest winds (upper surface) and coldest temperatures (lower surface).

A small disturbance in the sub-tropical jetstream over Western Australia features prominently in this morning’s WeatherTheatre Analysis, at 25-11-2013-18z. It can be seen in the adjacent WeatherTheatre snapshot as a tropopause front with a trailing vorticity tube to the mid-troposphere.  The disturbance is assisting a surface low over the Gascoyne/Pilbara region.

A mid-latitude upper front in its mature phase is apparent in a tropopause fold seen south of Western Australia in the background of the south-westerly perspective snapshot.  The easterly perspective snapshot shows it on the far right side.

In the background of the easterly perspective snapshot, a persistent upper disturbance and associated tropopause folding situated over the Tasman Sea is visible.  This is better seen in the south-easterly snapshot which shows a tiered appearance to the folding, due to the polar jetstream merging with the subtropical jetstream over the eastern Tasman.

The top-down perspective below provides a good indication of the geographic layout and extent of the features described.  The two disturbances in the west are visible on the left with darker shadings indicating the steepness of the tropopause surface in the frontal regions.

 

 

WeatherTheatre 25-11-2013-18z Snapshot

WeatherTheatre 25-11-2013-18z snapshot, top-down perspective.  The merging of the polar and sub-tropical jets is evident over the eastern Tasman in the far right. The disturbance in the sub-tropical jet over Western Australia is seen on the mid-left side and the disturbance south of Western Australia on the lower left.  Red shadings correlate with the strongest winds (upper surface and vectors) and warmest temperatures.  Conversely, blue shadings correlate with the weakest winds (upper surface and vectors) and coldest temperatures (lower surface).