Depending on your time reference, there are either about three weeks left in February (Dec/Jan/Feb is the meteorological winter for record-keeping); another five weeks remaining (per everyone's favorite rodent, Punxsutawney Phil, seeing his shadow on Sunday February 2); or about 40 days to go (vernal equinox--the official start of Spring--set for Thursday, March 20). But, no matter what your time and date benchmark for the change of seasons, it seems like this second week in February is the time when questions and comments about the upcoming growing season really start cranking up. And, while it may be too early to get a real good handle on what the trends will be for the upcoming 2014 growing season, there are certainly some features in the Pacific Ocean that bear some discussion.
Much of that attention is focused on whether the Pacific is moving toward an El Nino occurrence or not. El Nino is certainly being talked about. In the past week, there were reports coming out of the national ag convention circuit that highlighted calls for El Nino to form by early this summer; the implication being that such a development to be closely followed, if not accompanied, by increased precipitation over the southwestern Plains and the western Midwest. Weather agency predictions are cautious regarding this feature. NOAA's Climate Prediction Center (CPC) analyzes the Pacific outlook this way: "...the chance of El Nino developing after the spring is not much different from...neutral." And the Australia Bureau of Meteorology, in its latest Pacific analysis dated January 28, 2014 says "Most climate models...suggest the tropical Pacific Ocean will warm through the southern (hemisphere) autumn and winter. Some, but not all, models predict this warming may approach El Nino thresholds by early winter (northern hemisphere summer)."
So, where is this discussion with all this lingo going? Here's the point: right now (Monday Feb 10, 2014), the area of the Pacific that is analyzed for El Nino (warm ocean sea surface temps) and La Nina (cool ocean sea surface temps) is showing a cool trend--about one-half to one degree Celsius (about 1 degree Fahrenheit) below average for the time period from Jan 12 to Feb 8, 2014). This area of the Pacific--identified as "Nino 3-4" in the sea surface temperature maps--is actually showing La Nina-type leanings.
Along with that, the barometric pressure feature in the Pacific--the Southern Oscillation Index (SOI)--has also exhibited more of a La Nina-type trend than anything else recently. The Monday, Feb 10 2014 SOI values logged by the State of Queensland science department show a November monthly value of +10.1 (La Nina category); a December tally of -0.7 (neutral) followed by a January monthly value of +11.2 (La Nina). The 30-day SOI was again in La Nina territory at +12.5, with the 90-day figure at +6.9. The SOI daily reading was a -15.5, which is a value associated with El Nino.
Those recent SOI tendencies, along with the central Pacific region showing a cool water trend, lend a note of caution when it comes to making an El Nino call for this summer. The U.S. forecast model ensemble has the Nino 3.4 region temperatures reaching a value of about +0.8 deg C by August; the Australia forecast model ensemble is a bit cooler, at +0.3 by August. Neither of these values are even in the weak El Nino category. The indicated trend is neutral.
This is going to be a key feature as we move into the start of the spring--whenever you identify it--as well as the growing season (May through August). Because comparison charts of years when the Pacific was neutral before the growing season and then stayed neutral all season show mostly below normal precipitation in the Midwest, Plains, Far West (California), and the South. The only exceptions are above-normal precipitation in the northern Midwest (northern Iowa, Minnesota, western Wisconsin), southeastern Texas, and the southeastern U.S. El Nino offers above-average precipitation to the southwestern Plains and the eastern Midwest, but the key feature here is that El Nino needs to be in effect during the May through August time period--which does not appear to be forming at this time.