Saturday, June 12, 2010

MCS a plenty

 The storm track has been active enough to produce a number of MCSs. The movie above gives a fair depiction of the number of MCSs in the last 14 days or so. In fact over NE the 14 day rainfall departure has a large area of 4 inches above normal with peaks in the 8 inch range. The area shrinks if you go out 30 days but the numbers hold up. Pretty impressive narrow rainfall corridor.

Below are the 1000 hPa Reanalysis 2 temperature, 925 hPa specfic humidity, 850 hPa v wind, and 300 hPa vector wind anomalies maps. The low level warm anomaly centered over CO-NM is accompanied to its northeast by a large anomaly in specific humidity near 4 g/kg coincident with a 3 m/s v wind anomaly. The upper level jet is also anomalously strong and lies just north of NE where most of the MCS activity has been.

 [As an aside, this El Nino pattern for the interior Pac NW where I live has seen some abundant rainfall as well. My locale is 1" above normal as of June 10 which is the equivalent in climatology of October 1st! ]

The El Nino pattern and thus some of the seasonal outlooks  I have seen have suggested that the western Great Plains would be anomalously high in precipitation AND slightly below normal in terms of temperature. The funny thing about El Nino patterns for the Plains: the precipitation signal is weak but present, but the temperature signal is very weak. This is a new area of research for me so my discussion here is lacking. However, this particular El Nino emerged rapidly from a La Nina state {and is currently forecast to go back into a La Nina state}. This last happened in 2006 but previously did not happen since 1976.

In terms of the severe weather season we have been having, statistically it appears dull. The tornado count is hovering near the 25th percentile despite an active early May and an intermittent late May and early June.

This year has seen an active May (not compared to 2008) which is somewhat unusual on this graph but I dont believe is unusual over the last 20 years.  I will have to check that out.