Tuesday, July 8, 2014

A Midsummer Night's Summer Update

I cannot believe that once again it is time for the annual midsummer update.  Our weather has certainly started differently than the seemingly endless rain and cooler temperatures observed last year.  Let's review how the summer began and discuss where we are headed.


Image Source: NOAA Earth Science Research Laboratory

Noteworthy Features:

1) Warmest temperatures relative to average are in Northern Canada and to a lesser extent, he SW US and NW Mexico.

2) Bermuda High dominate the East with warm  not outrageously hot.  Here in NC, 90's in summer are expected even though late May and early June is more prone to the 80's for highs.

3) The cool high plains is somewhat La Nina-like.

4) Warmth NE of Hawaii is supportive.of the Bermuda High that dominated our June.

Ground Moisture

Image Source: NOAA Earth Science Research Laboratory

The wettest area in an almost La Nina fashion is the Midwest and Great Plains.  Severe drought in the Western US will certainly take its toll in the form of brutal heat (even by their standards) as their long term cyclical dryness feeds back.  Not evident on the big map is the mini-drought which I fully expect to reverse over the next few weeks.

The State of "El Nino"     

Data Source: The Long Paddock


My intention when seemingly poking fun at un-El Nino-like features when Ocean features and some atmospheric features indicate that one is making a good attempt to form is not to debate whether one is getting underway.  It is important to pay attention to the rest of the Globe as well in order to appreciate God's fantastic weather machine and anticipate the effects of features that are not yet cooperating with El Nino influences.

Oceanic features clearly indicate a forming El Nino.  The atmosphere is only partially cooperative.  An atmospheric index used over the long term to diagnose the state of ENSO called the Southern Oscillation Index has mostly been negative during the past 30 days yet the big positive spike and lesser one during  past few days contributed towards the running 30 and 90 day averages ing neutral.  Therefore we should not be surprised to observe weather outcomes that are not typical of El Nino.

Medium Range Outlook

Image Source:  University of Wisconsin SSEC

1) The Mega Ridge in the Southern Hemisphere is opposite of the summers of recent past when the feature was north of the Equator.  Dominance of that system over Australia IS a El Nino feature when present over the long term.

2) Typhoon Neoguri has turned NE as it approaches Japan.  This is a reliable 6-10 day predictor of a trough in the Eastern US.

3) Tropical energy surging towards a strong storm system that is traversing the westerlies.  The location of contact is important because  of  likelihood of building a Ridge west of Hawaii that reverses the +EPO that is involved in promoting the current Bermuda High.  

Based on the 3 features my expectation is to see a reversal of the heat and a dominance of 80's and increased precipitation here in Central NC and VA. in the 1-2 week timeframe.

Long Range - Through the end of Summer

1) Hottest part of the summer is over: Broadening wavelengths and the developing El Nino shift the mean trough towards the east coast.  Expect more 80's through the last 1/2 of summer.

2) Big SE Coast Tropical Threat:  Unless El Nino forces establish a full dominance ... warm SW Atlantic Ocean and an early summer tropical landfall in the same region are 2 predictors of late season trouble.

3) Big Winter ahead? -  In general, weak to moderate El Nino's bring persistent cold and more snow than usual to Central NC and VA.  If some other predictors line up ... then Winter 2014-15 would be very memorable.  That being said... we need to observe that El Nino succeeds and does not hard reverse like 2005-06 thus destroying winter.

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