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Blocking It is not impossible that the remarkable persistence of the current weather situation still arises from the extreme Sudden Stratospheric Warming (SSW) earlier in the winter, in January and February, made her mark. A strong SSW in the Arctic usually causes a strong blockage in the flow pattern at northern latitudes. While there the SSW now long no longer know the blockage in the pressure pattern still will not budge. A strong SSW in the winter above the Arctic in recent years we have seen way more often. Why so large a remarkable change in the temperature of the stratosphere is continuing, it is far from clear. Nor is it clear whether a possible increased incidence of a strong SSW part could be the globally changing climate.

Greenland is currently losing mass in two ways; surface melting with resulting runoff and iceberg calving from marine terminating glaciers. Over time we can expect some of these glaciers to retreat, pull their feet out of the water and prevent the second of these two forms of mass loss. We need to be careful extrapolating trends when we have recent to believe processes may change.I'll also add that elevation feedback is likely to become more important as we reach the ice sheet's tipping point. The ice sheet is only there today because it has its head in the clouds, it's a relic of the last ice age. Elevation feedback represents a hysteresis loop, with any significant lowering we can expect increased surface melt.

"The Deep South is going to be under the gun during during April...." So says Accuweather, in the latest update: http://www.accuweather.com/en/weather-news/severe-storm-outlook-2013/8893504

The Police in Hvolsvollur and the Civil Defense department have expressed concern over increased seismic activity around Hekla volcano in the past few days. Seven tremors have been measured in the last two weeks, a frequency which has never been matched since Hekla's previous eruption. According to geologists at the Icelandic Meteorological Office, the seven earthquakes were measured some 5 km from the top of the volcano and at a depth of 11 to 12 km. However, no magma movement has been measured. The volcano is being closely monitored at the moment by geologists who decided to alert authorities as Hekla eruption usually happen with very little warning, and the mountain itself is a popular hike among locals and tourists alike. The warning issued is the lowest out of three and is raised in order to initiate an appropriate and rapid emergency response in the case of an eruption. Internet users can monitor the activity around the volcano themselves with a live webcam of Hekla. Quite reassuringly, what looks like smoke at the top of the volcano is in fact just a cloud (at least for the moment). http://hisz.rsoe.hu/alertmap/site/?pageid=event_update_read&edis_id=VA-20130326-38648-ISL&uid=13518

Funny this one as Helka normally doesn't give much in the way of the warning has very little seismic activity basically aseismic. So normally activity starts 30 to 80 minutes after the first tremors. So I wonder is this just the crust settling due pressures in the region or Helka for once giving us plenty of warning.

I'm not sure about the PDO and how long any less negative/neutral phase would last as it is in a predominantly longer term negative phase. Wrt the stratosphere, i suspect the current remarkable -AO cold blocking regime is the last hurrah of the east QBO SSW/ wave activity which has dominated (overall) the winter and for sure the Spring season so far. It is common to have the strongest phase of blocking just prior to the end of an easterly QBO phase. And the reverse holds true in a westerly QBO regime when often some of the strongest +AO/zonal conditions prevail. The upcoming positive QBO phase and cold 10 hPa and 30 hPa stratosphere levels will have their part to play in due course and will surely make a difference to summer prospects once the current warm tropospheric conditions and associated remarkable surface conditions have waned. Maybe in turn that might mean much less excitement to anticipate for next winter? - but that is one for later in the year... It would be interested to know though what continued effect/mitigation the Siberian feedback process will have on the coming months with such anomalously cold conditions and SST's in place.Add in the chaos of the arctic ice patterns and nothing should be taken for granted. As others have said, I would also add thanks to the experts who have contributed and worked so hard to update this thread with some fascinating technical information. The stratosphere/troposphere relationship is a ground breaking area of meterorological science which the METO now acknowledge plays a significant role in our weather patterns. Well done to those on here who have played such a part in making this topic so mainstream and 'out there'