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Westwind

This section is simply describing what the various lines, coloured areas are, what interval/units the contours, isobars, colour-filled areas use etc. The use, or meteorological significance of the fields are dealt with in a separate section ... here

The Westwind site is here.

IMPORTANT: I am not going to attempt a description of the full range of products, just the ones that might be most useful to those who want to 'dip-in' without much knowledge. Also, the fields presented below are not necessarily from the same situation, run-time etc. They are there simply to aid a quick identification for each product. Many of these products 'mirror' those on the Top Karten site - so refer to the notes for that site to get the complete picture.

 


Georg Mueller (relay from Wetterzentrale site of GFS output (formerly AVN & MRF products)

 Example: Brief description of parameters (etc.) on charts shown.
 500 hPa, Bodendruck (MSLP), Re-Top (Thickness) (500/1000)
mslp_tthk_500
White lines: MSLP isobars (units = hPa / interval = 5 hPa)
Dark grey/dash & double-dot lines: thickness isopleths for the layer (500-1000) hPa. (units = dekametres [dam] / interval = 18 dam)
Colour shading: 500hPa height, colour coded as at scale by diagram. (units = dam / interval = 4 dam). Orange/Red high values - blue/indigo etc., low values.
Black line: the 552 dam contour (of the 500 hPa surface) - highlighted as the approx. median value to trace major troughs/ridges in pattern.
 Bodendruck (MSLP) und 850 Aeq.PT (Theta E)
mslp_850ThetaE
White lines: contours of 850hPa isobaric surface. (units = dekametres [dam]/ interval 4 dam)
Black solid/dashed lines: temperature at 850 hPa (solid >= 0degC; dashed < 0degC: units = degC / interval = 5 degC.)
Colour shading: value of Theta E (equivalent potential) temperature at 850 hPa as per shading chart at side/interval = 2 degC.) A better tracer than temperature alone, because it is based upon the dew-point as well as air temperature.
 Richtung (direction) & Betrag (strength/force) 10m Windes (winds)
10 metre wind fields
White 'arrows': 10m (i.e. 'surface') wind using conventional wind-barbs: e.g. arrow points in direction FROM which wind is blowing (NOT with the wind); a long feather = 10knots, a short feather = 5 knots, a triangle = 50 knots & speeds are built up using these combinations.
Colour shading: Wind speed (at 10m) colour shaded as scale at side of diagram (units = knots / interval = 2 knots). Blue/green light winds - yellow strong winds - red gales or stronger.
 2m Temperatur
2m temperature
Black/thin contours: 2m (i.e. 'screen' - level) temperature. (units = degC / interval = 10degC).
Colour shading: 2m temperature as scale at side of diagram. (units = degC / interval = 3 degC). Orange/Red high values - blue low values.
 6h - Niederschlag (Precipitation)
6 hrly ppn accum
Colour shading: 6 hourly precipitation (rain, snow etc.) in the period up to the time of the chart. See scale at side of chart - the deeper the blue the more precipitation - purple/violet etc., exceptional rainfall/snowfall accumulations. (units = mm): also displayed is a field labelled 'rot=Konvektion' (red dashed lines) which appears to indicate areas of PPN with a high convective / instability element.
 700hPa und Vertikalbew. (Vertical motion)
700 vertical velocity
White lines: contours of 700hPa isobaric surface. (units = dekametres [dam]/ interval 4 dam)
Black line: highlighted 700hPa contour at 300 dam. Useful to trace major changes in the pattern.
Colour shading: vertical motion as scale at side of diagram - yellow to red to violet: upward values; green to blue to violet: downward values. (units = hPa/h; interval 4 hPa/h)
NB: negative is upward motion!
 Bodendruck (MSLP), Wolken (Cloud)in %, ReTop (Thickness) 500/1000
mslp_cloud_tthk
White lines: MSLP isobars. (units = hPa / interval 5 hPa)
Coloured lines: 500-1000hPa thickness isopleths (units = dam; interval 18 dam)
Monochrome shading: % cloud cover based on medium level moisture (i.e. 'frontal') - see scale by side of diagram (black low % cloud values, light grey/white high % cloud values)
 850 hPa und Temperatur
850 tt etc.
White lines: contours of 850 hPa isobaric surface (units = dekametres [dam] / intervals = 4 dam).
Black lines: isotherms of 850 hPa temperature. (units = degC / interval = 5 degC).
Colour shading: temperature at 850 hPa- see scale at side of chart. (units = degC / interval = 2 degC, blue = cold, orange/red = warm).
 500 hPa, T (Temperature) und Bodendruck (MSLP)
mslp_500
White lines: MSLP isobars (units = hPa / interval = 5 hPa).
Dark grey/dash & double-dot lines: temperature at 500 hPa (units = degC / interval = 5 degC).
Colour shading: 500hPa height, colour coded as at scale by diagram. (units = dekametres [dam] / interval = 4 dam). Orange/Red high values - blue/indigo etc., low values.
Black line: the 552 dam contour (of the 500 hPa surface) - highlighted as the approx. median value to trace major troughs/ridges in pattern.
 200 (or 300, 500 etc.) hPa streamlines ("stromlinien") & wind strength ("windgeschwindigkeit").
200hPa output
 White lines (with arrows): streamlines following the wind flow at the level given. (Levels based on pressure levels - such as 500, 300, 200 hPa)
Colour shading: speed of wind - see the scale at the side of the chart; nearer to red / purple, high values; nearer to green/blue lower speeds.
NOTE: 300 or 200 hPa good approximation to jet level winds.

 


GME (German Weather Service, DWD), 'Global Modell' [ output via wetter.com ]

 Example: Brief description of parameters (etc.) on charts shown.
 10m Wind GME (kt) [ also isobaric pattern ]GME MSLP and Winds Blue lines: isobars (mslp) at 5 hPa intervals: (NB: as this is a German chart, High's are labelled 'H' (Hoch or Hochdruckgebeit - area of high pressure) and Low's are labelled 'T' (Tief or Tiefdruckgebeit - area of low pressure.)
Thick blue line: 1015 hPa isobar (nearest value to ISA standard.)
Black wind arrows: 10m wind forecast in knots (usual convention - see elsewhere).
Colour shading: Beaufort force groups - see scale at bottom of each chart.
 Tiefe (low) or Mittel (medium) Bewölkung (cloud cover)Low cloud and MSLP  Black lines: Isobaric pattern, every 5 hPa and 1015 hPa isobar highlighted in bold (see above).
Grey shading: from light to dark grey, according to scale (usually bottom/left), for 'FEW', 'SCT', 'BKN' & 'OVC' cloud amounts. (See the main FAQ here.)
 Example of an analysis with 'named' pressure systems (ex- Free University of Berlin)FUB analysis  Usual monochromatic chart symbology, but the major pressure centres are named: BLUE names for high centres, and RED names for low centres.

 


Wetter3 output based on GFS model (selection only .. many of the ideas are covered above).

 Example: Brief description of parameters (etc.) on charts shown.
 850hPa Fronten (objective frontal zones), Bodendruck (mslp) & 700hPa Vertikalbewegung (vertical velocity)
850Fr_mslp_700VV
White lines: MSLP isobars. (units = hPa / interval = 3 hPa (NOTE: unusual choice of standard isobars).
Colour-fill/shading: 700hPa vert. velocity - orange > red > purple implies upwards / negative values; green > blue implies downwards / positive values (see scale at right; units = hPa/hr.
Grey/thin lines: based on model parameters - close 'packing' indicates near-surface frontal zones using objective techniques.
 6 - stuendiger Niederschlag (6hr precipitation total in mm to hour given)6hr rainfall totals  Blue colour shading: light blue, low precipitation totals, dark blue (or purple), higher accumulation: see scale at right of diagram.
White lines (thin): contouring of same at 1, 5, 10, 25 and 50 mm.
 Niederschlagsstaerke (precipitation intensity) [mm/hr at hour given: 6hr time-steps] und Niederschlagsform (precipitation type)rain_snow output  Blue (Blau)/ Purple (Rosa) shading: blue shading for rain (regen) or freezing-rain (eisregen); purple shading for snow (schnee) or soft hail / snow pellets (Graupel). Intensity is given by the depth of shading - see scales at right-hand side (in mm/hr).
White (thin) lines: intervals of 0.1, 1, 2 (etc.) mm/h; Note that for the snow, the PPN is 'rainfall equivalent' not snow depth. (See notes HERE.)
 850hPa aequivalent potentielle Temperatur (ThetaE), Bodendruck (mslp)
850ThetaE_mslp
White lines: mean sea level isobars (see above) [hPa]/ interval = 5 hPa
Colour-fill/shading: 850hPa ThetaE field- see scale at right of chart. (blue = low, orange/red = high).
Light-grey lines: isotherms of 850 hPa ThetaE/interval=3 degC.
 2m Temperatur (2m temperature/degC)
[ similar conventions used for:
6-stuendige 2m Minimumtemperatur (min. temp), 6-stuendige 2m Maximumtemperatur (max. temp & 2m Taupunkt (dew point)].2m temperaturesW3_Tmax
Thin grey (with intermediate thicker white) lines: 2 metre (i.e. 'screen - level') temperatures. (units = degC / interval = varying 2 to 5 degC)
Colour-fill/shading: 2 m temperatures (actual, maximum in 6hr, minimum in 6hr or dew-point: see scale at right of chart. (purple/blue = low values, orange/red = high values). [NB: the dew point is a measure of the absolute humidity of the air - i.e. how much water vapour is carried at the particular level given - in this case 2m above ground level.]
 Tiefe (low), Grenzschicht (boundary-layer), Mittelhohe (medium) or Hohe (high) Bewoelkung (cloud) Isolinien (% probability)
LowCloud
Colour-fill/shading: shading (green) according to the legend at right-hand side of chart - deeper green, higher-probability of cloud. (I'm not sure of the cut-off for 'boundary layer' versus 'low' cloud.)
Blue/grey dashed (30,45), or solid (60+): lines of equal % probability of cloud cover at the appropriate level.
 10m wind (in knots/kn)
SFC wind
Standard wind barbs: where the barb points to the direction FROM WHICH the wind blows: with half-feather representing 5kn, a full-feather 10kn and a triangle 50kn.
The barbs are also colour-coded, where the sequence deep orange > red > violet indicates stronger to stormy winds: see the scale at right-hand side.
 850 (and 700, 500, 300, 200) hPa Geopotential (height fields) and Temperatur (temperature/degC)
850ht and T
 Black lines: contours of the pressure level given (i.e. 850, 700 etc.); intervals = 4 or 8 dam, with one contour highlighted as follows: 850hPa (144dam), 700hPa (300dam), 500hPa (552dam), 300hPa (912dam) and 200hPa (1176dam). The highlighting of one 'standard' contour allows broadscale pattern changes to be seen on image-loops.
Colour-fill/shading: 850 (or 700, 500 etc.) temperature fields - see scale at right-hand side of diagram.
White lines: on some charts, isotherms in degC, intervals usually 5degC .. see labels.
 850hPa FQn Divergenz von Q-normal (divergence of the component of Q, normal to the isotherms) und Fronten (objective frontal zones).
850FQnDiv
 Colour-fill/shading: deep red negative FQn, deep blue positive FQn: units = fractional degs. Kelvin per sec*m^2. (NB: some areas 'blank' data usually seen.)
Thin grey contours: frontal zones inferred from 850hPa model parameters.
 700hPa relative Feuchte (relative humidity %).
700RH
 Green shading: 60% or higher relative humidity at 700 hPa;
Lines (dashed low values, solid high values): 15, 30, 45, 60, 75 & 90% relative humidity at 700 hPa.
 500hPa Geopotential (height field) and Vertikalbewegung (vertical velocity in hPa/h).
500 and VV
 Black lines: contours of the 500hPa surface [ interval=8dam ]: 552dam contour thicker (used as a 'tracer').
Colour-fill/shading: see the legend at the right of the diagram. (yellow > orange > red > purple .. increasing vigour of upward motion [negative values]; green > cyan > blue .. increasing vigour of downward motion [positive values].
 500hPa Geopotential (height field) and absolute Vorticityadvektion (absolute vorticity advection/ per h^2)
500 and VortAdv
 Black lines: contours of 500hPa field, with 552dam highlighted - 8dam intervals.
Colour-fill/shading: absolute vorticity advection - for values see scale on right side of diagram. (Green > cyan > blue > purple: increasingly negative vorticity advection [ NVA / non - developmental ]; yellow > orange > red: increasingly positive vorticity advection [ PVA / developmental ]
 
500hPa Geopotential (height field) Bodendruck (mslp) & Relative Topographie (Total thickness).500 and TTHK
 White lines: mean sea level pressure isobars (in hPa or mbar); intervals=5 mbar.
Black lines: 500hPa contours in dam; intervals=8dam, with 552dam highlighted (thick black line).
Colour-fill/shading: 500-1000 hPa total thickness (TTHK) field (green > cyan > blue > purple: increasingly cold; yellow > orange > red: increasingly warm. See scale at right of diagram.
Light grey lines: TTHK contours at 4 dam intervals.
 500hPa Geopotential (height field) and Schichtdickenadvektion (layer-thickness advection)
500 and TTHKadv
 Black lines: 500hPa contours (see notes above: interval 8dam)
Colour-fill/shading: thickness (500-1000hPa layer) advection: - see scale at right-hand side, expressed as a fractional change in Kelvin (or degC) per hour.
(green > blue > purple: cold advection; yellow > orange > red > purple: warm advection: the deeper the colour, the stronger the advection. Crudely: strong WARM advection coupled to FALLING contour height=> strong SURFACE DEVELOPMENT.)
 500hPa Geopotential (height field) & Divergenz des Q-Vektors (divergence of Q-vectors).
500 and DivQ
 Black lines: 500hPa height field (see notes elsewhere - similar ideas with one contour 552dam highlighted, thick black).
Colour-fill/shading: FQ values as at the scale on right-hand side of diagram ... yellow > orange > red > purple: negative; green > blue > purple: positive. (See notes elsewhere).
 KO-Index & 500hPa Vertikalbewegung (vertical velocity).
KOIndexVV
 Varying width blue-black lines: KO-Index, every 2 degC (or K); one of many instability indices, based on Theta E at 1000, 850, 700 and 500. Broadly, higher negative values imply greater potential instability.
Colour shading: vertical velocity (or "V V" negative, upward only) - deeper red/purple, then more vigorous upward motion implied.
A combination of high V V (highly negative values) and high KO value=> strong risk of vigorous convection in frontal situations.

 

 UKMO products (modified output: 'FAX')

 Example: Brief description of parameters (etc.) on charts shown.
 FAX output (final product)
UKMO FAX product
These charts are simply standard 'FAX' charts which depict MSLP isobars (4 hPa intervals), fronts, pressure centres etc., to conventional symbology. For more on these, see the FAQ entry here) and for Conventional frontal symbology: click here for examples & further notes.

 

 ECMWF products.

 Example: Brief description of parameters (etc.) on charts shown.
 500 hPa & Bodendruck (MSLP)
EC image
White lines: MSLP isobars (units = hPa / interval = 5 hPa)
Colour shading: 500hPa height, colour coded as at scale by diagram. (units = dekametres [dam] / interval = 4 dam). Orange/Red high values - blue/indigo etc., low values.
Black line: the 552 dam contour (of the 500 hPa surface) - highlighted as the approx. median value to trace major troughs/ridges in pattern.