THURSDAY DECEMBER 30, 2010
New years Eve, rest of the week
The next few days should be mainly dry, although there are some light showers hanging around in the NI today and tomorrow, and last Q moon phase means rain, if about is more likely in the afternoon. The weekend should be clear for most of NZ, just some light showers around East Cape and the top of the SI - and the bottom half of the SI gets some light showers between tomorrow and Sunday. Any New years Eve parties should be relatively rain-free, with more cloud than rain.
The next 7-day interval for NZ is not a dry pristine one, unfortunately for campers, especially for East Cape southwards for the NI and a lot of the SI, and Taranaki gets some good rain at the end of next week. The top of NZ right through to BoP may get some next Monday or Tuesday. Waikato should be dry this weekend, with a bit of rain expected for next week and a lot more rain next weekend. The eastern BoP, e.g. Opotiki, may get some heavy rain next week and the following week, but it clears up for them from mid January to the beginning of March.And Hawkes Bay southwards and most of the SI get rain next week and next weekend.
Most sunshine for Auckland should be between mid January and mid February. The SI is not so clear-cut, with overcast skies and the look of rain during most weeks of the season.
The coming month should be drier than average for the NI except for a wetter Taranaki, Manawatu and Upper Hutt. The SI should be wetter than average for the West Coast and Otago southwards, but the rest, like the top and Canterbury and S Canterbury a drier than average month. Even saying that, for the east of the SI, the first half of January should be wetter than the second half. In January, anticyclones to the north of NZ may bring frequent N to NW winds, causing January to be very dry and sunny over the NI and the N and E of the SI. Soil moisture levels may be low over much of the NI and in Marlborough, Nelson and Canterbury, regions without significant rain for at least a month. The lack of rain plus high temperatures, wind and sunshine may bring increased fire risk to Bay of Plenty and Hawkes Bay. From mid January onwards, although wet and cloudy conditions may dominate Westland and the Southland coast, rainfall may remain low in Northland, Auckland and in the east of both islands, where no significant rain is likely until the first week in February. The warmest regions may be Hawkes Bay and from Marlborough to Otago. Frequent west to NWs may keep temperatures close to average in Wellington, Nelson, N Westland and Fiordland. Wellington may be windier than usual. Taranaki could be the weakest, with Levin and the central plateau not far behind. Russell may be the driest. Most rain occurs as the moon crosses the equator heading north in the second week, and as it crosses again heading south in the fourth week. January is a cloudier month than normal, with most sunny days between the 17th-24th. However north of Waikato most areas should be sunny from the 10th onwards.
January's perigee #9 (9th closest to earth for the year) occurs on the 22nd, two days after full moon and the day before the moon crosses the equator heading south. Higher tides are expected, disturbed westerlies and the passage of frontal systems, resulting in a round of showery activity that begins on 22nd in Fiordland and on south coasts and by 23rd becomes widespread across the NI, with a southwesterly change across the SI. The system should dissipate after the 26th. Heatwaves will be expected in NSW and temperatures are expected to reach above 30C in some NZ districts e.g. Alexandra within a week of this perigee.
Cyclone watch, January
15th-22nd: forms at or near New Calendonia around 10th, traverses towards the Queensland coast by 16th, then downgrades to a low as it passes across the top of Northland around 18th-20th. Another low, perigee(22nd)-related, forms over the Solomons around the 20th, another in the Coral Sea off the coast of Queensland around the 24th and a further one around New Caledonia around the 30th. All of these are likely to remain tropical lows.
These are days in summer on which the weather is liable to change towards higher winds or lower temperature. They are also a guide as to earthquake occurrences. Abbreviations: N=new moon, F=full moon, 1stQ=first quarter, lastQ=last quarter, P=perigee,(P#4=fourth closest for the year), A=apogee, XhS=moon crossing equator heading south, also called lunar equinox, XhN=moon crossing equator heading north, ^=northern declination, also known as north stitial colure, V=southern declination, also known as south stitial colure.
JAN 2nd Sun V
JAN 4th Tues N
JAN 10th Mon A, XhN
JAN 17th Mon ^
JAN 20th Thur F
JAN 22nd Sat P9
JAN 23rd Sun XhS
JAN 27th Thur 3rd
JAN 30th Sun V
FEB 3rd Thur N
FEB 6th Sun A, XhN
FEB 13th Sun ^
FEB 18th Fri F
FEB 19th Sat P5
FEB 20th Sun XhS
FEB 25th Fri V, 3rd
MAR 5th Sat N, XhN
MAR 6th Sun A
MAR 12th Sat ^
MAR 19th Sat XhS
MAR 20th Sun P1, F
MAR 25th Fri V
MAR 27th Sun 3rd
There's a solar wind stream flowing from a coronal hole right now that should reach Earth on Jan. 1st or 2nd--the first solar wind stream of the New Year. And that may bring some more earthquake activity to Christchurch between 2nd-4th. Also it's the new moon next Tuesday and the tides will be high. Earthquakes cluster mostly around P and from now till March may mostly span the combination of F, P and XhS. N also brings increased risk because of the kingtide under the land.
General weather hints
If rain is about, it is most likely to fall:
During new moon (N): sunset to sunrise
During first quarter (1stQ): midnight to midday
During full moon (F): sunrise to sunset
During third quarter (3rd): midday to midnight
Rain is more likely to fall on or about moonrise, moonset, when the moon is midway between moonset and moonrise, or at three-hourly intervals between these. Rain can also fall on the turn of a tide at a coastal location.
Wet or dry
When perigee (P) or apogee (A) is close to the new (N) or full moon (F) e.g.less than 36 hours between, a dry weather-week on either side can be expected. When P or A is more than two days away from the nearest N or F, a wet period a week either side may be expected.
Southern declination (V) brings mainly drier weather to the north, southerlies and inclement weather in the southwest. Southern declination tends to bring higher barometer readings and shallow depressions.
Northern declination (^) generates wetter conditions in the north, and drying winds to the south. Northern declination tends to bring showers and low barometer readings, followed by northerlies, shallow anticyclones, and warm and humid conditions.
Declinations and the moon crossing the equator and heading north or south (XHN and XHS) generally bring change within two days, especially changes to the wind.
An anticyclone forming just before southern declination or just after northern declination will tend to move to the southeast. A depression just after northern declination will tend to move northwest to southwest.
Gustier winds typically occur within two days of ^, V, XhN, XhS, P and A If any two of these combine in the same period, winds are likely to be even stronger.
Weather changes often occur around the day of ^, V, XhN and XhS. Weather can also typically change on the day of the beginning of a new phase: N, 1stQ, F or 3rd.
Full moon can bring clear nights and cloudy or wet days in winter or very hot days in summer. Winds tend to swing to come from the north or northeast, and lighten. On the day of full moon, the wind typically drops to almost zero. In winter, rain or snow often eventuates just before or within two days after full moon. A phase change often brings a weather change. More settled weather often comes a day before a phase change.
New moon can bring rain at night but humid days and not over-warm. Around new moon, wind tends to come from the west, solid at ground or water level. Rain can also be expected within two days after new moon. New moon days are usually pleasant, with less chance of extreme weather.
Heavy frosts can also occur with a new moon if it is a clear night. Frosts also occur between full moon and the third quarter.
Full moon to last quarter is the worst time for thunderstorms, hail, tornados, and, during summer months, tropical cyclone formation. It is also the worst burn-time in summer, for children and animals. Full moon days are often dramatic, with unkind heat in summer and cold temperature drops in winter. If electrical storms, hail and tornados are about, they will more typically occur before the moon rises or after it has set.
Higher tides occur at the following times: around 4th and 23rd. They are good periods for fishing because more fish come in with the increased water volume, and diving is better on the low side of the kingtide. Kingtides are also times to watch for increases in rain and storm systems, and land disturbances. For harvesting, best to pick at the low tidal variation so crops are not waterlogged.