How Does MCS Outflow Affect a Warm Front?

[Eric Sipes]

Hi,

It was recently pointed out to me that on 4/9/08 the MCS outflow North of the warm front had accually stalled the front causing storms to fire further South than progged on the previous day's model runs. This I can understand but, it raised a few questions.

1: How does this affect the warm sector south of the front, if at all?

2: Does this reduce or increase the chances of severe storms along and South of the front? (Please explain)

3: Can this affect the hodographs and tornado possibilities in severe storms that do occur?

4: We did not have very much success on this day because of technical and visibility problems. We lost the Breckenridge storm in the Abilene area due to low clouds and no radar. We did get another storm Northwest of Sweetwater but, it was completely shrouded in fog. (still no radar) Could the low clouds and fog South of the front have been a byproduct of the MCS outflow?

Thanks,
-Eric

 

[Mike Hollingshead]

I guess I never noticed any mcs outflow stopping the warm front that day. I'd say the really cold air aleady in place north of it does a good job at that on its own.

1. Shouldn't affect things south of the front, as it would essentially become the front.

2. I'd say a really sharp temperture change along a front like that is a big big issue for storms. I've seen plenty of fronts like that, and not once have I seen what I'd say was a great storm.

3. I don't see it changing hodos much, though perhaps holding it up would sharpen it and make the winds back sharper. Just like I've never seen anything great on a sharp front with very cold air close by, I've never seen anything great on new outflow boundaries.

4. I'd say the fog, etc, was thanks to moisture advecting over the cold front back there...and the cold air slipping south, lifting the warmer moist air. I drove south all day in the air north of the front. It was cold cold out. That's another thing, I can't think of many cool storms I've seen with that kind of cold air entrenched near the target area. I think it was near 40 in Alva OK when I got there the night before at 10pm. I was like, this ain't good. Cold air loves to win battles.

From the moment the storm of the day fired, you could see it having issues thanks to the sharply cold air right north of the front. Perhaps the storms to the north that morning enhanced the cold air some, I don't know. I'm not sure it would have mattered much without those. Hell as cold as it was, they could have brought down warmer air, lol.

 

[Eric Sipes]

Thanks for answering my questions. Those were the answers I was looking for.

As for the MCS, It started as scattered elevated "crapvection" in the TX panhandle and formed into a linear squall line in Wrn OK. As it collapsed during early afternoon, it pushed a very cold outflow boundry S and E which stalled the warm front.

This was well represented in the morning model runs that showed the WF as an almost quarter circle from near Duncan, OK to Abilene, TX to the triple point S of Lubbock, TX. It was only later that it was pointed out to me why the models had changed so drastically.

Thanks again,
-Eric