Tracking Weekend Rain

Friday, January 30th 2015, 4:21 am

By: Alan Crone

The split flow pattern will become active for the southern plains soon. This will bring rain chances into the state Saturday along with colder air Sunday into next week.   Moisture will more than likely quickly leave the area Sunday morning with little in the way of mixed precipitation across the region, but we'll keep a very low chance in the forecast for the first half of Sunday.

A southern stream area of low pressure is developing near the Baja today and will become “cut off" from the upper flow during the next 24 to 36 hours.   The northern stream, consisting of a northwest flow over the central plains, will bring a weak disturbance into the area Saturday evening and a stronger mid-level trough into the region Sunday.   The net impact will be an increase in rain for the state Saturday and an influx of colder air Sunday.

If you've been following this system with me in the blog that last few days, you're aware of the issues we've had with the Sunday period.   The data has been inconsistent regarding how quickly the moisture exits the region and fast the colder air will arrive over northern OK.   It appears the data has centered closer to a consensus solution yesterday and we're still seeing some of this in the morning runs.   The rain will be nearing the area Saturday, more so in the latter half of the day into the evening hours, before moving eastward Sunday morning out of the state.   The timing of the exiting precip Sunday is still a little tricky and will still require us to keep a decent pop for the morning hours, but this should quickly move out of the state.   It does not appear that we'll have any appreciable window for impactful wintry precip Sunday.   As the mid-level trough in the northwest flow brushes the state, colder air at the surface will flow from the northwest to the southeast.   Temperatures Sunday may start in the lower 40s before oozing into the mid-30s to upper 30s by late Sunday afternoon with gusty north winds. The southern stream cut-off does not move into the plains this weekend, but will eventually get a kick across Texas Tuesday night into Wednesday. The current trajectory of this ejection would favor the Wednesday rain remaining south of the Northeastern OK vicinity. This precip (Wednesday) may remain along or south of the Red River into the Lone Star State.

As the southern stream low ejects, the northwest flow will drive more cold air into the region.   Wednesday into the end of next week may become very cold with another surge of modified arctic air brushing the Missouri Valley and part of eastern OK.   We'll need to watch carefully by the end of next week making sure no southern stream disturbances can bring moisture into the region.   The EURO has a system, while our GFS brethren remains dry.

In summary, we're expecting some early to mid-morning sun across the eastern third of the state today with highs in the upper 40s.   Clouds will increase from the southwest to northeast later today.   The rain chances will remain high Saturday with highs in the 40s.   A few showers may be possible early Saturday morning, but additional rain will become more likely Saturday afternoon and evening.   Sunday morning rain will be exiting the area as temperatures drop into the 30s with gusty north winds by afternoon.

Thanks for reading the Friday Morning weather discussion and blog.

Have a super great day!

Alan Crone
KOTV