Monday, January 7, 2013

Pattern shift: warmer but wetter weather on tap

Yesterday (January 6), the Memphis metro saw it's first 50-degree day since Christmas Eve!  Typically 52 degrees wouldn't feel that warm, but in the context of 30s and 40s the past week and a half, it was rather pleasant!  While today's weather is much like yesterday, more "spring-like" weather is expected for the rest of the week.  And with springtime temps typically comes spring storms - this week will be no exception.

The culprit for this week's wet weather will be an upper level low pressure system that will move out of Baja California across northern Mexico and into Texas by Wednesday.  It will then lift north-northeast towards the Midwest on Thursday and weaken somewhat.

An upper-level low over central TX Wednesday evening will lift north-northeast by Thursday. The track is not particularly favorable for severe weather in the Mid-South.

As the upper-level low moves northeast, surface low pressure over Texas will begin to lift north during the same time frame.  A warm front extending east from the low will lift towards the region Wednesday, bringing increasing rain chances and the possibility of some thunder as it moves through the region Wednesday night. As the surface low moves northeast Thursday, it will drag a cold front through the Mid-South.  The cold front will encounter unseasonably warm and moist Gulf of Mexico air in place over the region and thunderstorms will be a good bet, probably Thursday afternoon.

Precipitable water values Wednesday evening show high moisture content in the atmosphere ahead of the approaching weather system, meaning the possibility of heavy rain.

As low pressure in OK lifts northeast Thursday, the cold front entering western AR will move through and could bring a round of thunderstorms. The Mid-South will be in the "warm sector" behind the warm front all day.
Meanwhile, a warmer pattern will begin to take hold this week and will be augmented by the arrival of the Gulf airmass.  While temps will approach 60 on Tuesday and Wednesday, highs Thursday ahead of the cold front could reach 70. Behind the front, the airmass moving in will be of Pacific (not Canadian) origin, so mild temperatures will continue on Friday, which may also see highs approach 70.  Another system will move in for the weekend, bringing high rain chances once again.  Much cooler temperatures will trail that system as we end the weekend and start next week.

While the threat of severe weather does not look particularly high on Thursday, an isolated severe storm cannot be ruled out, with damaging wind being the most likely threat it appears.  Any storms on Wednesday or Wednesday night would be "elevated" in nature (meaning the lift within the storms does not originate at the Earth's surface), so thunder and lightning will be possible, but the severe weather risk is very low.  The main concern with both systems in the coming week will be heavy rain. And considering the lack of rainfall over the past several months, this may not be a bad thing. Rainfall totals of 2-3" are very possible with the mid-week system while another couple of inches is definitely possible this weekend.

Projected 7-day rainfall amounts through Monday, January 14. The Mid-South could see 4-6" rainfall totals from the next two weather systems.

We'll keep you updated as the week goes along.  Follow MWN on Facebook and Twitter for the latest info and download our  iPhone or Android app for the most recent forecast and always-current StormView Radar, as well as severe weather warnings for the location(s) nationwide that YOU are most concerned about.  Our complete forecast can be found here on

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