1227 replies to this topic

[Cloud 10]

492, on 20 March 2012 - 15:46 , said:

GFS FI has been indicating a marked warming at 10hpa which looks as dramatic as the warming that occurred during January. This predicted warming looks more dramatic than what I would have expected for normal seasonal warming. If it verifies are we likely to end up with a Greeland high later in April with deepish cold air over the UK.

Quite a sharp warming showing up at 30hpa as well,albeit at day 10.




Perhaps more model output like the chart below to come over the next week or so.

[492]

The continued predicted warming at 10hpa on GFS results in the PV that has been resident to the east of Greenland for most of the winter being entirely replaced by a significant warm area albeit deep in FI. If it verifies It will facinating to see how much this affects the troposphere during the second half of April.

[Glacier Point]

Glacier Point, on 16 February 2012 - 22:46 , said:

Want to try something here. Based upon the projection of the tropical waves, mountain torques and warming of the stratosphere, to attempt to predict either a strong warming event of potentially early final warming.

As the MJO wave moves through the Indian Ocean, it can trigger strong posiitve mountain torques over the Himalayas. Currently very negative, these mountain torques reversing could potentially trigger remote wave breaking and disruption of the polar vortex.

So key timelines to watch for:

- MJO moving through phase 3/4 and developing high amplitude - - 1st March

- Strong positive mountain torques and rapid increase in tendency in relative angular momentum -- 1st - 10th March

- Rapid increase in high and middle stratosphere temperatures -- 12th through 22nd March

- Blocking signatures in the troposphere developing -- 22nd March through 11th April.

- MJO moving through phase 3/4 and developing high amplitude - - 1st March

.. moved through several days later on, 5th-6th March

- Strong positive mountain torques and rapid increase in tendency in relative angular momentum -- 1st - 10th March



.. first mountain torque on 10th March and second on 20th March, not overly impressive but a very impressive spike in tendency in angular momentum centred on 12th March (I suspect this is causal to current modelling indicating blocking structures in high latitudes).

- Rapid increase in high and middle stratosphere temperatures -- 12th through 22nd March

No rapid increase seen as yet, although 30 mb temperatures have gone above normal and 10 mb forecast to rise above normal today (was the lack of a strong Asian Mountain torque the issue here?)

- Blocking signatures in the troposphere developing -- 22nd March through 11th April.

Tropospherically, definate signs of this, more Gulf of Alaska and Pacific side - probably more related to tropospheric influence rather than stratospheric ?

Edited by Glacier Point, 28 March 2012 - 20:39 .

[phil n.warks.]

As expected warming out of the vortex is forecasted at all levels as we go into April.

10 day temp. and zonal wind reduction forecasts at high latitudes show up here.
http://wekuw.met.fu-...wfzm_t_f240.gif
http://wekuw.met.fu-...wfzm_u_f240.gif

The pressure forecasts from CPC suggest as the vortex wanes and fragments the main core of low heights transfer towards N.Siberia via Scandinavia.
http://www.cpc.ncep...._z70_nh_asc.gif
supporting current trophospheric modelling of a cooler north westerly flow in early April and the prospect of heights in the N.Atlantic.

[Alex]

I'm assuming no change and we are heading into the final warming phase?

[summer blizzard]

Warming has only propogated own to 10hpa so far, so no final warming just yet.

[Mr_Data]

This thread seems to have died.

Here's the temperature graphs for the 2011-12 season


http://wekuw.met.fu-...alert=1&lng=eng

[492]

Mr_Data, on 30 April 2012 - 19:10 , said:

This thread seems to have died.

Here's the temperature graphs for the 2011-12 season


http://wekuw.met.fu-...alert=1&lng=eng

This is fascinating as the marked warming in early to mid January appeared to link directly to western moving block over northern Siberia later in the month. The Siberian high migrated westwards at around 60 to 65 N maintaining a central pressure of 1060HPA over a period of a week or more. The result was a very unusual outbreak of Siberian air over the southeast of the UK and intense cold over much of Europe. I would think that actual Siberian air reaching the UK is a very rare event indeed and has probably only occurred on one or two occasions in the last 100 years.