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Sunday, April 23, 2017

unsettledness... (pm.23.apr.17)>

Sunday's stats:

Low temp: 57.4F (14.1C)
High temp: 71.5F (21.9C)
Rainfall: 0.07" (2mm)

It's mostly cloudy as dusk settles in this evening, here at the end of the coolest day since the 10th of April.  The low temperature occurred during thundershowers with very gusty winds right around 4:00am, and then the high temp occurred very late in the afternoon -- right around 4:20pm -- when we had a nice spell of sunshine.  All of the paltry amount of measurable rainfall today occurred during those predawn thundershowers, with only a trace of rain during a period of thunder, sprinkles and drizzle during the mid-afternoon.

We're still in the midst of a major transformation of the upper-level pattern which started on Wednesday of last week, and won't really complete its cycle until the middle of this new week.  The huge high pressure ridge responsible for a long stretch of abnormally warm weather has entirely broken down now, and is being replaced by a trough of low pressure in the upper atmosphere which is now centered right along the Afghanistan border with northern Pakistan.  This system is going to be wobbling only slowly eastward during the next couple of days, and will keep our weather on the unsettled and unstable side, as a batch of colder air aloft drifts over the top of relatively warmer air in the lower levels, while mixing in a moderate amount of moisture.  As we have seen, rainfall amounts have so far been very light, but we've been dealing with regular periods of cloudiness, showers, thunder and gusty winds for a few days now.

Models are in a fair state of disagreement, but the most reliable data suggests that we'll see some stabilization as early as Tuesday, but more like by Thursday.  We'll have to keep an eye on the risk of isolated thundershower development all week, actually, but it looks like temperatures will be on the rise again by the coming weekend, taking us back into the slightly above normal range as May arrives...