Tuesday, December 9, 2014

Cooler on Wednesday

By Jay Grymes & Steve Caparotta

WAFB First Alert Quickcast:

- mornings in the 30°s and cooler afternoons for Wednesday & Thursday
- warming temps into the weekend
- stays dry through Sunday

We got a little chillier this morning than expected. As it was, our Tuesday morning forecast of 39° for Baton Rouge was below most of the computer models and the NWS forecast too. However, it wasn’t low enough: the Red Stick dipped to 36° this morning, with mid to upper 30°s over much of the Florida Parishes and into SW Mississippi. There were even some reports of light, early-morning patchy fog for the morning commute.

Other than the patches of light-to-moderate fog, it was a mainly-clear sky start to Tuesday and we stayed that way through the day. Sunshine helped push afternoon highs to 70° or more for some WAFB communities. Skies will stay mainly-clear through this evening and overnight.

A reinforcing dose of dry Canadian air is sliding through the Bayou State and that sets us up for a pair of cooler days for Wednesday and Thursday. Look for afternoon highs in the upper 50°s to low 60°s across the WAFB viewing area under high, cirrus clouds for much of the day then go to partly cloudy skies for Thursday. We’ll stay under a north to northeast flow for both days as well. So which of the two upcoming mornings will be the coldest? 

We’ve noted in the past that it is often the second morning that sees the lowest readings after a continental (Canadian) air mass surge. What may get in the way of this soft rule-of-thumb is the potential for a better cloud deck from Wednesday into Thursday morning. So for now, we call for mid to upper 30°s for Wednesday morning for metro Baton Rouge, with some of our northern viewers potentially getting close to a freeze. Then its upper 30°s for Baton Rouge on Thursday morning with mid 30°s for Thursday’s sunrise along the LA/MS state line.

By Friday, winds will swing around to the east, possibly even to the southeast later in the day ... and that will signal the start of a warming trend. We’re thinking the low to mid 60°s for Friday afternoon, then the upper 60°s for Saturday and up to around 70° or so for Sunday. But throughout the period, we stay dry. (Good news for shoppers but we really could use some rain!)

As mentioned yesterday a large, lumbering storm system currently over the eastern Pacific will move into the West Coast over the coming days. By Sunday, the latest NWS guidance shows double-barreled lows associated with the western upper trough and storm system: one surface low over the upper Mississippi Valley and another low in the Southern Plains. 

The southern low looks like it will be a rainmaker for us on Monday, but the intensity and severe threat remains unclear. Yesterday’s guidance suggested a better potential for strong storms than today’s model runs, but as you well know, Monday is just too far down the road for us to have forecast confidence at this stage. So stay tuned ….

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