Experimental Melbourne Long Range Weather Forecast

(and Experimental Three-Month Victorian Seasonal Outlook
and Experimental Port Phillip Bay Forecast
and Experimental Terminal Aerodrome Forecast)

Based Upon Statistical Interpretation of NOAA Data

Combined With Human Forecasts

(http://www.arl.noaa.gov/ready.html)

NOAA Data At: 4pm, 31-7-2010

Minimum temperatures are for the night/early morning,
maximum temperatures are for the daytime,
whilst precipitation amounts and probabilities
are for the 24 hours from midnight.

Day & Date	Morning	Afternoon	Min Temp (deg C)	Max Temp (deg C)	Precip Amount (mm)	Precip Prob (%)	9am Wind/ 3pm Wind Melb Apt (km/hr)
Mon-2-8-2010	Rain.	Rain.	7	13	3.1	87	WSW 25 SW 30 Gusts65
Tue-3-8-2010	Cloudy.	Cloudy.	8	15	0	38	NW 12 W 15 Gusts40
Wed-4-8-2010	Shower.	Shower.	8	13	0.7	55	WSW 12 SSW 15 Gusts35
Thu-5-8-2010	Fog.	Sunny.	5	13	0	20	VRB 3 S 8 Gusts20
Fri-6-8-2010	Partly Cloudy.	Cloudy.	5	14	0	25	N 12 N 20 Gusts40
Sat-7-8-2010	Windy.	Windy.	6	15	0	39	N 30 N 35 Gusts75
Sun-8-8-2010	Windy.	Windy.	8	15	0	43	N 30 N 35 Gusts75
Mon-9-8-2010	Cloudy.	Shower.	8	15	0.9	59	N 35 N 35 Gusts75
Tue-10-8-2010	Cloudy.	Shower.	7	15	0.8	52	N 20 N 25 Gusts55
Wed-11-8-2010	Cloudy.	Shower.	8	16	1.6	59	N 30 N 35 Gusts75
Thu-12-8-2010	Shower.	Shower.	8	15	2.1	65	NW 12 W 15 Gusts40
Fri-13-8-2010	Cloudy.	Shower.	8	15	0.8	58	NW 12 W 15 Gusts40
Sat-14-8-2010	Cloudy.	Cloudy.	7	16	0	37	N 12 N 20 Gusts40
Sun-15-8-2010	Possible Shower.	Possible Shower.	7	16	0	42	N 20 N 25 Gusts55

The Weather Icons

Acknowledgement: Bureau of Meteorology & World Meteorological Organisation

Sunny

Dry

Haze

Mist

Fog

Partly Cloudy

Cloudy

Windy

Dust

Possible Shower

Drizzle

Shower

Snow

Rain

Thunder

Cyclone

Definitions

Icon	Meaning
Sunny:	Sun shines >75% of the time
Dry:	As 'sunny', but used on days when Max > 30 Deg C & Relative Humidity drops below 10%
Haze:	As 'sunny', but used on days when visibility drops below 5000 m due to smoke
Mist:	Visibility below 5000 m due to water droplets but above 400 m (also used on days when isolated fog patches)
Fog:	Visibility below 400 m
Partly Cloudy:	Sun shines between 25% & 75% of the time
Cloudy:	Sun shines <25% of the time
Windy:	No precipitation & wind speed averages 'fresh' (18 kts) or stronger
Dust:	Visibility <1km due to dust raised by wind
Possible Shower:	Isolated light precipitation <25% of the metropolitan area
Drizzle:	Liquid precipitation that is almost continuous & made up of fine droplets
Shower:	Brief periods of liquid precipitation
Snow:	Snow or sleet falls (includes cases of flurries and/or ice)
Rain:	Liquid precipitation that is almost continuous but droplets are of medium size or large (not fine)
Thunder:	Thunder heard or lightning seen
Cyclone:	Wind speed averages 'storm force' (60 kts) or stronger

Weather Pattern for Mon-2-8-2010:
Deep low over south Tasman Sea.
Strong unstable southwesterly flow across Victoria.

Bay Forecast

SW wind of 20 to 30 knots.
Waves of 2 metres.

Click image below for
Andrew Watkins Bay Winds

Melbourne Terminal Aerodrome Forecast (TAF)

TAF YMML 1212 27025G45KT 8000 -SHRA SCT010 BKN035
FM21 25020G40KT 6000 SHRA SCT008 BKN025
FM03 23025G45KT 8000 -SHRA SCT010 BKN035

RMK
T 9 7 6 6 Q 1013 1016 1018 1023

THREE MONTH OUTLOOK FOR AUG/SEP/OCT:

NCEP's Depiction of the Global Sea Surface Temperature Evolution

Matt Wheeler's 10-Day Forecast of the Madden Julian Oscillation's Evolution

The average Indian Ocean Dipole Mode Index for the past week is -0.04 (-0.08 standard deviations), the average Southern Oscillation Index (SOI) for the past 90 days is 10.14, the average SOI for the past 30 days is 18.56, and the latest recorded bimonthly Multivariate ENSO Index (MEI) is -0.412. The expected MEI, adjusted by the Indian Ocean Dipole Mode Index and also by recent values of the SOI, for JUN/JUL is -0.44. Such a value of MEI indicates a sea surface temperature distribution that corresponds to a very weak La Niña. This suggests:

RAINFALL: There is a very slightly enhanced chance that total AUG/SEP/OCT rainfall will be above normal in the MALLEE, WIMMERA, NORTHERN COUNTRY, NORTH CENTRAL, NORTHEAST, WEST GIPPSLAND, CENTRAL and WESTERN Districts, but there is little indication as to whether total AUG/SEP/OCT rainfall below, near or above normal in the other Victorian District, EAST GIPPSLAND.

OVERNIGHT TEMPERATURES: There is a very slightly enhanced chance that average AUG/SEP/OCT overnight temperatures will be above normal in the WIMMERA, NORTHERN COUNTRY, NORTH CENTRAL , NORTHEAST and WESTERN Districts, but there is little indication as to whether overnight temperatures will be below, near or above normal in other Victorian Districts.

DAYTIME TEMPERATURES: There is a very slightly enhanced chance that average AUG/SEP/OCT daytime temperatures will be below normal in all Victorian Districts.

The relationship between ENSO, the Indian Ocean Dipole (IOD),
and the rainfall, overnight temperature, and daytime temperature
at Australian Capitals over the forthcoming 30 days.

Click on the Australian Capital of interest (only Melbourne available at present)

30 DAY OUTLOOK FOR MELBOURNE:

Today's scientists talk in terms of the continent's large climate variability from season to season, and from year to year. What causes these fluctuations? They are, in part, connected with the climate phenomenon called the Southern Oscillation, a major air pressure shift between the Asian and east Pacific regions whose best-known extremes are El Niño events and La Niña events. The Pacific Ocean is a huge mass of water which controls many climate features in its region. Its equatorial expanse, far larger than the Indian or Atlantic Oceans, is critical to the development of the Southern Oscillation and the El Niño and the La Niña. The Multivariate ENSO (El Niño Southern Oscillation) Index, which combines the Sea Surface Temperature (SST) distribution across the Pacific with various features of the atmospheric circulation, is used to monitor the evolution of the El Niño and Southern Oscillation phenomena. The MEI is a bimonthly index which is calculated at the end of each month. The most recent MEI is -0.412 standard deviations. This reflects a mild La Niña event. This most recent value may be adjusted by taking into account the values of the Southern Oscillation Index averaged over the past 30 and 90 days to yield a more representative expected current value of the MEI. The expected MEI is -0.8 standard deviations. This would reflect a moderate La Niña event.

Another region of Sea Surface Temperature variability that impacts on Australian climate is that of the Indian Ocean. One mode of variability that appears to affect Australian rainfall, particularly the south east of the country, is the Indian Ocean Dipole (IOD). The IOD referred to here is defined by an index that is the difference between SST in the western (50°-70°E, 0°S-10°N) and eastern (90°-110°E, 10°-0°S) tropical Indian Oceans. A positive Indian Ocean Dipole Mode Index (DMI) occurs when the western basin is warmer than average and the eastern basin is cool and hence the DMI is positive. These regions were proposed in a paper by Saji et al. (1999) on the Indian Ocean Dipole that showed a modulation in Australian seasonal rainfall with DMI positive and negative years. The current Indian Ocean Dipole Mode Index (DMI) is -0.08 standard deviations. This reflects a neutral Indian Ocean Dipole state.

Also impacting upon Australian climate variability is a phenomenon known as the Intra Seasonal Oscillation (ISO) (also known as the Madden-Julian Oscillation (MJO), after Madden and Julian, who first identified it in the early 1970s). They discovered that, at many locations in the tropics, surface pressure and upper atmospheric winds tend to go through a coherent cycle over periods of about 40 to 50 days. It has been found that a broad area of active cloud and rainfall propagates eastwards around the equator at intervals of between about 40 and 50 days. These are not strict time limits - research over the years has pushed the limits of the oscillation's period to between about 30 and 60 days. The Madden-Julian Oscillation (MJO) is presently operating in Phase 3. This is reflected in the near-equatorial enhanced convection being found over the over the eastern Indian Ocean. Following Phase 3, the region of enhanced convection often moves from the eastern Indian Ocean to the western part of what is referred to as the Maritime Continent (Indonesia).

In Melbourne, at this time of the year, a combination of the MEI, the DMI, and the MJO Phase, such as what we have operating now, suggests, over the following 30 days:

RAINFALL: There is a 38% chance of it being wet, a 33% chance of normal rainfall, and a 29% chance of it being dry.

Wet Weather Dry Weather Normal Weather

OVERNIGHT TEMPERATURES: There is a 45% chance of warm nights, a 32% chance of normal overnight temperatures, and a 23% chance of cool nights.

Warm Nights Cool Nights Normal Nights

DAYTIME TEMPERATURES: There is a 39% chance of warm days, a 33% chance of normal daytime temperatures, and a 28% chance of cool days.

Warm Days Cool Days Normal Days

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