Tuesday, May 13, 2014

Summerlike Warmth Returns for First Days of June

I'm expecting summerlike warmth to come back for the first week or so of June.

The image above shows projected 500mb height anomalies over the northern hemisphere. We can signify the blues with negative height anomalies, which indicate the presence of cooler and stormier weather, while reds denote positive height anomalies, which allow for warmer than normal and calm weather. In the image above, if we look towards the Bering Sea, we can see a very strong ridge of high pressure, seen by the splotch of red around the Aleutian Islands. This image is valid for May 13-14, and if we extrapolate it out 2-3 weeks using the Bering Sea Rule, we can expect high pressure and warm weather to appear in the East US.

If we look at another 500mb height anomaly forecast graphic, this one valid on May 19th, we now see that our strong ridge has shifted west into the middle of the Bering Sea, with cooler, stormier weather now protruding into western Alaska. This tells us that we can expect warm temperatures in the first several days of June in the middle of the country, with cooler conditions along the Eastern Seaboard.

This warmth is supported by long range modelling of enhanced tropical convection around the central Pacific, which is typically associated with warmer than normal weather in the Central and East US in the May-June-July time period. The bottom panel in the graphic above demonstrates the enhanced convection (blue) present in the Central Pacific.



Joseph Renken said...

The initialization is the 13th and the 2-3 week from date is the 19th. Which places it June 8th for the warmth to move in. ;)

Anonymous said...

Andrew, I’m wondering if there’s something in particular that is driving the dew points so high already. We had the polar vortex that you explained so well. It brought us the extreme cold this winter. But is there an opposite to it that causes such high dew points? Last summer we had quite decent temps but our dew points were at minimum in the upper 60s all summer long. We’ve already seen some of that this year and it’s not even officially summer. We all expect higher dew points in the peak of summer but to have them so early, or to have them last all summer seems odd.