Warm soil temp.'s: big modifying effect on later cold?

[LarryWx]

The very warm (vs. normals) weather of the last weeks has undoubtedly resulted in soil temp.'s that are well above normal through much of the U.S. and probably near record highs in many cases. My understanding is that these very warm soil temp.'s aren't input into most (if not all) models. So, I'm wondering if the moderation of Arctic airmasses by the time they reach down here in the south would tend to be significantly underdone at the surface in model forecasts. Keep in mind I'm not talking about the issue of the current lack of snowcover, which I realize is a modifying influence itself.

I'll rephrase it with a hypothetical example:

Let's say we are trying to predict low level temp.'s for three different scenarios for FEB 10th for Dallas, TX. Let's assume it is now 1/30 and that there will be a major Arctic outbreak plunging deep down into the U.S. and reaching to Dallas and beyond on 2/10. Assume that for all three scenarios the Arctic airmass is of identical strength up in Canada and identical in all ways. To avoid differences in snowcover and cloudcover confusing the issue, assume they are both zero for the entire U.S. and will remain that way through FEB 10th. Assume identical soil moisture in all cases. Here are the scenarios:

Scenario A: JAN has averaged 10 above normal for the entire U.S.
Scenario B: JAN has averaged near normal for the entire U.S.
Scenario C: JAN has averaged 10 below normal for the entire U.S.

1) Would actual 2/10 temp.'s for Dallas likely verify significantly warmer (say several degrees) for scenario "A" vs. "B" and for "B" vs. "C"?

2) Would models be assuming the soil temp.'s of scenario "B" (i.e., near normal soil temp.'s) no matter what since apparently current soil temp.'s are not an input? If so, would that mean models would tend to verify too cold for Dallas on 2/10 for scenario "A", about right for scenario "B", and too warm for scenario "C"?

Thanks in advance for any help.

[cctxhurricanewatcher]

That is right on. That's why we will not get anywhere close to record cold. The Dec 83 and 89 outbreaks were preceded with cool to cold weather. Similar outbreaks or cold snaps since then were the same.

[Tyler]

That is right on. That's why we will not get anywhere close to record cold. The Dec 83 and 89 outbreaks were preceded with cool to cold weather. Similar outbreaks or cold snaps since then were the same.

Jan/Feb 1989. Record warmth to record cold.

[richtrav]

That is right on. That's why we will not get anywhere close to record cold. The Dec 83 and 89 outbreaks were preceded with cool to cold weather. Similar outbreaks or cold snaps since then were the same.

Jan/Feb 1989. Record warmth to record cold.

My thoughts exactly, although Feb '89 was not extreme cold like Dec 83 or 89. The worst freeze to hit Texas when warm conditions had prevailed beforehand was in 1951.

[PTrackerLA]

I figure there are 3 factors working against a major cold outbreak for the deep south. 1) Lack of snowcover up north, 2) Warm soil temps, 3)Increasing sun angle and intensity. Combine that with the "arctic outbreak" continuing to be delayed and I just don't think we're going to see very cold temps. Temperatures tonight would be 5-10 degrees cooler if there were a snowpack in the midwest but with one of the warmest January's on record it's just not going to happen. We could still see a light freeze mid/late February as they are fairly common but it's looking less likely that we'll have a hard freeze this winter. Winter 2005/2006 will go down as the warmest since the 1990's.

[Extremeweatherguy]

That is right on. That's why we will not get anywhere close to record cold. The Dec 83 and 89 outbreaks were preceded with cool to cold weather. Similar outbreaks or cold snaps since then were the same.

Dec. 1989 started out with record warmth and then the first of a three part series of arctic outbreak came through (mid month) and began to cool things off. Even the first (and least extreme) of the three outbreaks was able to bring freezing rain to Houston and a low of 19. Also, Feb. 1989 (as mentioned earlier on this thread) was proceeded by one of the warmest January's ever...and during that Feb. we saw an prolonged freeze event in Houston with a trace of snow. The best example of this though is 1951 (also previously mentioned). During that outbreak we had a 5-day freeze and over 1.71" of freezing rain. So to say that record cold could not happen would be an incorrect statement.

[Hybridstorm_November2001]

Excellent point LarryWx. I'm still seriously doubting that this cold will last much longer than a week. Sorry, but that is just the way I see it. A snap, no trend.

[Extremeweatherguy]

I figure there are 3 factors working against a major cold outbreak for the deep south. 1) Lack of snowcover up north, 2) Warm soil temps, 3)Increasing sun angle and intensity. Combine that with the "arctic outbreak" continuing to be delayed and I just don't think we're going to see very cold temps. Temperatures tonight would be 5-10 degrees cooler if there were a snowpack in the midwest but with one of the warmest January's on record it's just not going to happen. We could still see a light freeze mid/late February as they are fairly common but it's looking less likely that we'll have a hard freeze this winter. Winter 2005/2006 will go down as the warmest since the 1990's.

Actually if you would look at some of the other posts, you can see that it has happened before. Once again Feb. 1989 was proceeded by a warm Jan. and followed by a cold Feb. Also, all it will take is a few good storms to replenish the snow cover to the north, and that can happen in a matter of a few days (it does not take a month). As for increasing sun angle...if that was the case then why have Houston's heavies snowfalls occurred in February? also, why did parts of Galveston Bay freeze over in mid February 1899? Seems like the sun angle was not a factor then.

[LarryWx]

Nice discussion on both sides folks. To clarify, I'm not really trying to take either side. I'm just trying to read everyone's responses and learn. I will say that logic tells me that very widespread warm U.S. soils for the time of year would have to make at least "a little" difference since there's in essence a source of excess heat for the time of year, the ground. But "a little" is not "much". That is the issue for me. Is it "much" or only "a little"? Is it, say, <1 degree or is it, say, 3-5 degrees+? IF it is "much", are most models going to tend to be too cold for 2 meter temp.'s just because of this issue alone?

Even if the answer is "much", I would assume that any subsequent Arctic airmasses that follow pretty quickly would tend to modify less and less as the U.S. soil cools rapidly. But again, my questions are about an INITIAL Arctic airmass.

[LarryWx]

I figure there are 3 factors working against a major cold outbreak for the deep south. 1) Lack of snowcover up north, 2) Warm soil temps, 3)Increasing sun angle and intensity. Combine that with the "arctic outbreak" continuing to be delayed and I just don't think we're going to see very cold temps. Temperatures tonight would be 5-10 degrees cooler if there were a snowpack in the midwest but with one of the warmest January's on record it's just not going to happen. We could still see a light freeze mid/late February as they are fairly common but it's looking less likely that we'll have a hard freeze this winter. Winter 2005/2006 will go down as the warmest since the 1990's.

Actually if you would look at some of the other posts, you can see that it has happened before. Once again Feb. 1989 was proceeded by a warm Jan. and followed by a cold Feb. Also, all it will take is a few good storms to replenish the snow cover to the north, and that can happen in a matter of a few days (it does not take a month). As for increasing sun angle...if that was the case then why have Houston's heavies snowfalls occurred in February? also, why did parts of Galveston Bay freeze over in mid February 1899? Seems like the sun angle was not a factor then.

I'm assuming that the always changing sun angle is properly handled by modeling since it doesn't vary from year to year on any particular date.
By the way, Atlanta's all time record low was, indeed, 2/13/1899. So, despite the rising sun angle, the coldest was that late in the winter. So, in my mind, it is possible to have extreme cold into mid-FEB. Now once to late FEB (say after ~2/20), history suggests it is extremely difficult to get that kind of extreme cold. It can still get very cold, but all-time record cold doesn't seem to be a reasonable possibility by then. Record lows tell me that.

[Tyler]

I figure there are 3 factors working against a major cold outbreak for the deep south. 1) Lack of snowcover up north, 2) Warm soil temps, 3)Increasing sun angle and intensity. Combine that with the "arctic outbreak" continuing to be delayed and I just don't think we're going to see very cold temps. Temperatures tonight would be 5-10 degrees cooler if there were a snowpack in the midwest but with one of the warmest January's on record it's just not going to happen. We could still see a light freeze mid/late February as they are fairly common but it's looking less likely that we'll have a hard freeze this winter. Winter 2005/2006 will go down as the warmest since the 1990's.

1)Lack of snowcover really does not matter when you have this type of airmass moving in from Canada. There is a bitterly cold airmass over Alaska, and its going to take a LONG time for it to modify. 2)I seriously doubt that could affect a serious outbreak of cold. 3) Sun angle doesn't come into play until mid-March (Just look at Feb/March 2002)

[jasons2k]

I figure there are 3 factors working against a major cold outbreak for the deep south. 1) Lack of snowcover up north, 2) Warm soil temps, 3)Increasing sun angle and intensity. Combine that with the "arctic outbreak" continuing to be delayed and I just don't think we're going to see very cold temps. Temperatures tonight would be 5-10 degrees cooler if there were a snowpack in the midwest but with one of the warmest January's on record it's just not going to happen. We could still see a light freeze mid/late February as they are fairly common but it's looking less likely that we'll have a hard freeze this winter. Winter 2005/2006 will go down as the warmest since the 1990's.

1)Lack of snowcover really does not matter when you have this type of airmass moving in from Canada. There is a bitterly cold airmass over Alaska, and its going to take a LONG time for it to modify. 2)I seriously doubt that could affect a serious outbreak of cold. 3) Sun angle doesn't come into play until mid-March (Just look at Feb/March 2002)

Here's my $.02 on the subject:

The 3 factors cited by PTracker are indeed true...but with caveats.

Lack of snowfall does moderate the cold air. But it's the flipside that's most important; snow on the ground allows the air to cool much more efficiently at night and keeps it in check during the day. A snowpack to the north certainly helps keep the air cold. However, it is true with very cold air if it comes fast enough it won't modify much. It also depends on the depth, flow, and other factors as well.

The NWS DFW uses soil temp. a lot in winter to rule out accumulating winter precip. when conditions are marginal. They are usually right about that, but I really don't know much about how soil temps influence the air temprature...other than if your "soil" is all concrete then it's gonna be hot.

Finally, increasing sun angle is also a factor - even in February. The examples cited above really don't mean a whole lot in this discussion other than to point out that significant cold waves, even record-breaking ones, can occur late in the season. OK, so they can. What they are not saying is that later in the season, freezes become increasingly infrequent, and the risk for such a freeze decreases. The average date for the last freeze at Galveston is Jan 27th, Houston Hobby is Feb 4th, Beaumont Feb 18th, and Feb 25th at Bush/Intercontinental.

Even though winter "officially" began on the day of the solstice in December, that's the day the sun began fighting back. The atmosphere lags behind about a month - most of the northern hemisphere is coldest for AVERAGES in mid January. The ocean, since water requires more energy to heat, takes a bit longer to bottom-out and begin the rise.

In summer, the opposite occurs, with most of the warmest averages in July-August and the warmest waters from Aug-Sep - no concidence the peak of hurricane season.

Anyway, back to the sun-angle. The fight begins immediately, the effects are delayed, but they have already started. The average temp in Houston bottomed-out at 41/62 earlier this month. Tomorrow the average lo-hi is 42/64. By the end of February it will be 48/70. In addition, we have 10 more minutes of sunlight now than we did back in December - and sunlight = heat.

This early in the season, the effect may not be much. But it does make a difference, even if it is only a degree or two. I can pretty much guarantee that if the Feb 1899 outbreak had been in January instead, the records would be even lower than they were.

As time passes, the sun angle will increase and the days will grow longer, and the cumulative effect will ultimately win the battle...at least for a few months until it swings the other way.

[richtrav]

JS

Interesting conjecture about Feb 1899, but it seems that most Arctic outbreaks that have been strong enough to affect the entire subtropical region of eastern North America from the western Gulf in South Texas and Tamaulipas over to Florida and eastward have occurred in either December or February and not the middle of winter. Coincidence perhaps? At any rate I cannot imagine how cold 1899 would have been if it had occurred a month earlier; it was already a 200-year event at the very least. I still can't believe it was 8 degrees in Galveston at 10:30 in the morning under a cloudy sky with the wind blowing, and -1.5F the previous night in Ft Worth - at 7pm!

[Brent]

Excellent point LarryWx. I'm still seriously doubting that this cold will last much longer than a week. Sorry, but that is just the way I see it. A snap, no trend.

and not "extremely" cold considering the time of year.

This is not December 1989 or January 1985. Sorry.

[cctxhurricanewatcher]

JS

Interesting conjecture about Feb 1899, but it seems that most Arctic outbreaks that have been strong enough to affect the entire subtropical region of eastern North America from the western Gulf in South Texas and Tamaulipas over to Florida and eastward have occurred in either December or February and not the middle of winter. Coincidence perhaps? At any rate I cannot imagine how cold 1899 would have been if it had occurred a month earlier; it was already a 200-year event at the very least. I still can't believe it was 8 degrees in Galveston at 10:30 in the morning under a cloudy sky with the wind blowing, and -1.5F the previous night in Ft Worth - at 7pm!

That's kind of like the way summer works in these parts too. Most of our extreme, all time record breaking stuff has occured in June or August or Early September. Not in the middle of the summer. I guess the same is true for winter.

[Air Force Met]

That's kind of like the way summer works in these parts too. Most of our extreme, all time record breaking stuff has occured in June or August or Early September. Not in the middle of the summer. I guess the same is true for winter.

Except the summer of 1980...in July...which was the hottest month in Houston History.

[richtrav]

Ahh yes, good ole 1980. The hottest reading in San Antonio, however, came in September 2000, and in Brownsville I know it came in March. I even think the last two years our highs have come in May or September

[cctxhurricanewatcher]

In Corpus, our time record high was broken during a week where we had 100+ degree temps in June of 1998. Then it was broken again in Sept 2000. I think the record now stands at 109. Both of those mini heat waves were during very hot summers and they were desert like heat. I recall going to a high school football game here in Corpus during that Sept 2000 record breaking event and the kickoff temp was around 105 at 7:30 PM. No seabreeze what so ever.

[Air Force Met]

In Corpus, our time record high was broken during a week where we had 100+ degree temps in June of 1998. Then it was broken again in Sept 2000. I think the record now stands at 109. Both of those mini heat waves were during very hot summers and they were desert like heat. I recall going to a high school football game here in Corpus during that Sept 2000 record breaking event and the kickoff temp was around 105 at 7:30 PM. No seabreeze what so ever.

Yep...Sept 2000 was hot for a stretch and Houston had record temps...and for a period it was hotter than 1980...but for an overall period...as far as entrenching heat for an extended period...1980 is king. It didn't stop.

I remember the cracks in the yard mroe than anything. We have black gumbo soil down here and the cracks in the yard were so big you couldn't play because you could twist your ankle.

Those of you in SE Texas know what I'm talking about with that gumbo soil and droughts. You could lose a small child in that stuff.

[cctxhurricanewatcher]

In Corpus, our time record high was broken during a week where we had 100+ degree temps in June of 1998. Then it was broken again in Sept 2000. I think the record now stands at 109. Both of those mini heat waves were during very hot summers and they were desert like heat. I recall going to a high school football game here in Corpus during that Sept 2000 record breaking event and the kickoff temp was around 105 at 7:30 PM. No seabreeze what so ever.

Yep...Sept 2000 was hot for a stretch and Houston had record temps...and for a period it was hotter than 1980...but for an overall period...as far as entrenching heat for an extended period...1980 is king. It didn't stop.

I remember the cracks in the yard mroe than anything. We have black gumbo soil down here and the cracks in the yard were so big you couldn't play because you could twist your ankle.

Those of you in SE Texas know what I'm talking about with that gumbo soil and droughts. You could lose a small child in that stuff.

Yea, 1980 is still the King of Heatwaves. As far as cracks in soil. Well the vacant lot next to my house has some pretty big cracks right now. And this is without any sort of excessive or summertime heat.