Saturday, August 18, 2012

Upper level atmospheric pattern holds the key to our cooler weather

The hot stagnant upper level pattern we experienced throughout the summer seems to have taken a backseat to a more progressive one, more typical of early fall.  A progressive pattern features passages of ridges of high pressure and troughs of low pressure ever y few days that bring some variety to our weather.  As you've noticed, we've had a couple of rounds of strong thunderstorms move through the area this past week with somewhat more pleasant days dominated by high pressure that is not as unrelenting as we experienced this summer.

The forecast for the week ahead holds some of the same.  In fact, with yesterday's cold frontal passage, we are now moving into a period where an upper level trough will have an effect on our weather pattern, meaning cooler temperatures, less humidity, but still some rain chances, mainly this weekend. This morning, a round of showers and thunderstorms is moving east through southern AR, throwing clouds over our area, as well as the possibility of some light showers, though most rain will remain to the south of the metro.

Upper level (30,000') pattern Saturday morning featuring a massive trough in the east and large ridge in the west.
Another impulse will bring yet another area of rain to the Mid-South tomorrow. This one could be a little further north than today's, so it appears we'll have slightly better rain chances on Sunday.  Again, southern Arkansas and Mississippi will see the brunt of the rainfall, though the northern edge could be over the metro, bringing primarily light rain.  If, like a couple of the models indicate, the rain area moves even further north, we could see off and on rain throughout Sunday. For now, we expect most of it to remain to our south however.

Upper level pattern for Monday shows a sharper trough over the Mid-South and a ridge still dominating the west.
By Monday, the trough deepens over the area, pushing any rain chances further south and we'll enter a period of mainly sunny skies and low humidity for the first half of the work week. BY Wednesday, the trough will move east and upper level ridging will move take it's place over the region. This will lead to a warm up, but still no major surface fronts that are expected to bring rain. In addition, humidity looks to remain tolerable through the end of the week. Highs will warm from the low-mid 80s to start the week to near 90 by week's end. Mornings should be particularly pleasant this week with lows near 60 in the suburbs (slightly warmer in the city), warming somewhat by late week.

By Thursday, the upper level trough shifts east as ridging builds into the Plains and towards the Mid-South. 
So, once we get through clouds and some rain chances this weekend, the Mid-South should enjoy a fine weather week of below normal temperatures and abundant sunshine! Click here for the full forecast from MWN or get the forecast, and lots of other great Memphis weather info, anytime on our mobile apps for iPhone and Android devices (links below).

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