The East Pac Is Jacked!

Sea surface temperatures in the tropical and subtropical eastern Pacific are running generally at least 1ºC above average and 2–3ºC above average west of Mexico (lower panel below).  A warm tongue of warm water off the coast of South America and along the equator is indicative of El Nino conditions.

Source: NOAA/CPC

El Nino years are typically associated with above average hurricane seasons in the east Pac and we've already had two names storms, Andres and Blanca, both of which have reached Category 4.  Andres has dissipated, with the last remnants of its cloud mass near 23 N and 123 W.  High clouds extend northeastward from the Andres remnants and into the southwest US.  Blanca is still churning away.  Although it has weakened to Category 2 strength, having attained Cat 4 earlier, it represents the earliest second major hurricane on record in the east Pac.

Source: NOAA/NHC

The showers that came through the Salt Lake Valley this morning can be traced to a surge of moisture originating in the subtropical eastern Pacific just to the east of Andres.  The loop below, which covers the past 2 days and includes contours of integrated water vapor (a.k.a., precipitable water) and 850-mb winds shows this surge nicely.  Note how the moisture tongue pushes across Arizona and wraps across eastern Utah into the northern part of the state.  

If you are wondering if this is a trend for this summer, it's tough to say.  An above average hurricane season in the east Pac seems to have a good chance.  Monsoon precip from July–September?  Less clear for our part of the world.  El Nino stacks the deck in Arizona for below average monsoon precipitation, but not so much northern Utah (our monsoon precipitation is fickle here to begin and can be hit or miss, making all these statistical inferences "dicier").  Based on a variety of factors, the Climate Prediction Center is giving us slightly better than chance odds of above average precipitation.  I wouldn't bet the farm on this (or even a small side wager), but I'll hope it verifies and I'll enjoy anything that falls from the sky the next few days.