Dec 062013
 

NW Europe is being battered by a powerful winter cold front responsible for severe winds, snowfalls, and heavy rain and flooding.  The WeatherTheatre SceneOne, 5-12-2013-12z, Vertical and Planar Views show a strong upper cold front, signified by a deep tropopause fold, and associated strong polar jet apparent in the red shadings across the NE Atlantic and NW Europe.

The upper front has lead to a deep surface low over southern Norway and steep pressure gradients to the south of the low centre, driving gale force winds.   Forecast models indicate the low rapidly moving across to western Russia by the weekend as the upper front progresses east.

WeatherTheatre SceneOne 5-12-2013-12z, Europe, Vertical Northerly View

WeatherTheatre SceneOne 5-12-2013-12z, Europe, Vertical Northerly View. A deep tropopause fold is notable in the background, shaded red due to a strong polar jetstream. The fold obscures a steep 300K theta surface indicating very cold polar air behind it. 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 5-12-2013-12z, Europe, Top-down Planar View

WeatherTheatre SceneOne 5-12-2013-12z, Europe, Top-down Planar View. A strong jetstream (red shadings) is seen entering NW Europe near the top of the view. The tropopause is obscured by the a very high 300K theta surface (the blue area) north of the jet, indicating cold polar air. 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).

Dec 052013
 

A burst of unseasonal, wintry weather is sweeping across southeast Australia due to a strong, upper cold front in association with a shortwave disturbance crossing the region. The front is triggering widespread rain, thunderstorms and mountain snowfalls.

The WeatherTheatre SceneOne, 4-12-2013-12z analysis, vertical views reveal a deep, narrow tropopause fold along the upper front enveloping a peak in the theta surface where cold polar air is situated behind it.  A narrow elliptical, polar jet filament on the planar view is characteristic of the short wavelength of this disturbance.

Surface cyclogensis is occurring in response to the upper front and strong thermal gradient over southeast Australia.  Forecast models indicate a surface low forming near the southern NSW coast rapidly developing and moving southeast across the Tasman Sea in the next 24 hours.

WeatherTheatre SceneOne 4-12-2013-12z Australia Southeasterly View

WeatherTheatre SceneOne 4-12-2013-12z Australia Southeasterly View. A deep, narrow, curved tropopause fold (upper surface) revealing the upper front envelopes the 300K theta (lower) surface, indicating the associated cold air.  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 4-12-2013-12z Australia Top-down View

WeatherTheatre SceneOne 4-12-2013-12z Australia Top-down View. A narrow shortwave trough associated with the upper cold front moving over southeast Australia is revealed by the sharply curved, positively tilted, elliptical polar jet filament, seen in the red shadings on the tropopause, which merges with the subtropical jet at the apoapsis. 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 4-12-2013-12z Australia Westerly Vertical View

WeatherTheatre SceneOne 4-12-2013-12z Australia Westerly Vertical View. The upper front features prominently on the left of the image where it is revealed by a tropopause fold enveloping a mounded theta surface associated with the cold air. 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 4-12-2013-12z Australia Northerly Vertical View

WeatherTheatre SceneOne 4-12-2013-12z Australia Northerly Vertical View. A cut-away view of the upper front stands out in the foreground, showing the theta mound in the centre surrounded by a folded tropopause in the frontal zone. 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).

Dec 042013
 

Plummeting temperatures, heavy snowfalls and freezing winds are blasting the NW USA as a strong winter front progresses east.

A deep, tropopause fold envelopes and intersects with a steep, mountainous, Theta surface, revealing a vigorous Arctic cold front, slicing through most of the troposphere, in the WeatherTheatre SceneOne 4-12-2013-0z Northeasterly View.

The typical upward slope of the Theta surface from tropics to polar regions is apparent at zonal points in the WeatherTheatre Orbital Sweep, culminating in a steep ascent in the frontal region.

The front is inducing surface cyclogenesis with most forecast models indicating a low over Colorado will drift northeast and rapidly deepen in the next 48 hours.

WeatherTheatre SceneOne 4-12-2013-0z Orbital Sweep

WeatherTheatre SceneOne 4-12-2013-0z North America Orbital Sweep.  A strong front ‘hangs’ over the NW USA, showing up as a curtain fold of the tropopause (upper surface).  Typical meridional upward slope of the Theta (lower) surface from tropics to polar regions is apparent at zonal points of the sweep, with a notable steep ascent near the front.  The frontal fold intersects with the Theta surface and this is apparent from northerly points (looking south) in the sweep where bits of the tropopause can be seen beneath the Theta surface.  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 4-12-2013-0z Northeasterly View

WeatherTheatre SceneOne 4-12-2013-0z Northeasterly View. A strong Arctic front is vividly revealed by a deep tropopause fold (upper surface), partially obscuring a mountainous theta surface which is indicative of a polar atmosphere. 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).

Dec 032013
 

A strong, upper cold front is situated south of Australia, in the background of the WeatherTheatre SceneOne, 3-12-2013-0z Analysis, Southerly View.  The front is marked by a deep tropopause fold and associated elevated theta surface behind, indicating a good depth and spread of cold air following.

A tongue of warm air stretches across Southeast Australia preceding the front, reflected in the valley in the 300K Theta surface, where the intersection with the surface corresponds to the 27 degree celcius isotherm.  Forecast models project widespread rain across Southeast Australia ahead of the front and the cold-air behind the front should bring unseasonal snowfalls to the Southeast Australia mountains on Thursday, 5th.

A tropopause lowering over the Tasman Sea, seen on the left side of SceneOne and coming into view in the last few frames of the Southerly to Westerly Orbital View, is associated with a cut-off low which is expected to gradually weaken in the next two days.

WeatherTheatre SceneOne 3-12-2013-0z Southerly to Westerly Orbital View.

WeatherTheatre SceneOne 3-12-2013-0z Southerly to Westerly Orbital View. A strong upper cold front appears south of the continent in the first few frames. A cut-off upper low over the Tasman, which is also driving a cut-off surface low, comes into scene in the last few frames as a lowered tropopause in the top 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).

WeatherTheatre SceneOne 3-12-2013-0z Southerly View

WeatherTheatre SceneOne 3-12-2013-0z Southerly View. A strong, upper cold front stands out in the background, apparent by the folded tropopause (upper surface), shaded red due to the strong jetstream winds associated with the front. The fold wraps around a large mound in the 300K Theta surface below which provides an indication of the depth and spread of the cold air. 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).

Dec 032013
 

A deep, winter cold front is sweeping over the NW USA from Canada and the NW Pacific, bringing a blast of Arctic air with widespread snowfalls.  The WeatherTheatre SceneOne, 2-12-2013-12z Analysis, dramatically illustrates the front responsible for the icy weather.  The front is marked by a deep folded tropopause, extending through most of the depth of the troposphere and dominating the centre field of view.  A steeply sloping, high theta surface intersects the fold, indicating the depth and extent of the frigid Arctic air following the front.

WeatherTheatre SceneOne 2-12-2013-12z East-Northeasterly View

WeatherTheatre SceneOne 2-12-2013-12z East-Northeasterly View. A deep tropopause fold (upper surface) intersects with the 300K Theta (lower surface), associated with a strong blast of Arctic air sweeping over the NW USA. 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).

Dec 022013
 

A cut-off, upper low over the Southern Mediterranean is driving a deep surface low near Sicily, causing widespread heavy rainfalls over the central Mediterranean. The 1-12-2013-18z WeatherTheatre SceneOne Analysis, Northerly Perspective, shows a dramatic tropopause curtain fold (upper surface), wrapping around with the upper low circulation, and an associated raised Theta surface immediately below. Forecast models show the low persisting and slowly moving southeast, then gradually weakening from the 5th.

WeatherTheatre SceneOne 1-12-2013-18z Northerly Perspective Snapshot, showing a cut-off upper low with dramatic tropopause fold near the middle 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).

WeatherTheatre SceneOne 1-12-2013-18z Northerly Perspective Snapshot, showing a cut-off upper low with dramatic tropopause fold near 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).