The center green band of these NOAA charts delimits the 20 year average for each day, the bottom marking the average minimum temp and the top marking the average high temp. The red and blue portions of the chart mark the range of temps between that and their record high and low levels. The dark blue ‘bars’ show the actual recorded temps for those days. This chart shows distinctly the initial cold span with the slight warming to well within normal range, followed by a more irregular cooling. The relative steadiness of these temperatures helped plants maintain their slower, more dormant metabolisms for the month. Typically February has been notable for the stability of its daily temperatures, the relative narrowness of the ‘green, normal, band’ indicates this.

This chart for March again shows the slowly warming/rising light green normal band contrasting with the dark blue bars of our actual temps. The March temps appear colder because they shifted the chart downward. The more extreme minimum temperature swings of Nov., Dec., and Jan. have even out, the lt. blue portion narrowing and showing more consistency.

It’s 41ºF at 5:30am on Mar. 12 as I begin to write this.  We appear to have come out of the longest sustained ‘cold’ period of the winter of ’18-’19 which began on February 4 and continued through Mar. 11, a period of 36 days.  Over those days we had freezing minimum temps at PDX, the official NOAA reporting station for the Portland area, on 26 of them.  On two of those days, Feb. 6 and 7, PDX recorded the winter’s lowest temp, 23ºF, making it a zn 9a winter, mild for us historically and especially so for the temperate US as a whole, much of which was experiencing its own much colder temps.  It’s mid-March and our high temps have climbed well above what they were and our forecasts call for milder, more ‘normal’ highs and lows now locally.  It looks likely that not only are we going to be on the ‘warm side’ of normal, but that our lows have shifted into a pattern well out of the freezing range.  (State ODF meteorologist, Pete Parsons, calls for a pattern of slightly warmer and drier weather than normal over March, April and May with the highest chance of this during May.) 

While weather consists of moments, recorded data points, we attempt to make sense of it in its patterns over time…our experience of it.  In this we are much like our plants.  Plants too have their ‘expectations’ of the weather and those conditions that take them outside of them, outside their familiar patterns, the relatively quick changes and perturbations, as well as the longer sustained patterns, and extremes, are ‘noticed’ and make a difference.  How does this winter compare? Continue reading →