Basketball > Weather... Maybe More Interest Thursday?

Well, internet issues again didn't allow me to post Friday as I had planned, but it looks like in an overall sense, the Friday - Saturday severe weather event did not live up to what some models had been portraying, which of course is good news for those that were in the path of the storm. As such, the weekend wound up a good one to watch some hoops. My forecast for a UNC title still is alive at least, though I only got half of the Final Four correct this year.

Anyhow, with basketball on a break until the weekend, it is back to searching for threats in the current weather pattern. The next notable threat I see is on Thursday, and interestingly enough is in many of the same areas that were under the gun back on Friday. The pattern seems to want to repeat itself to some degree, with a series of lows coming out of the Rockies and into the Plains, then heading to the Mid-Atlantic, and that is what looks to occur Thursday and Friday of this week. I have two maps below. The first is the 500 mb forecast off the NAM valid Thursday afternoon. Yeah the NAM is not known for being stellar beyond like day 1, but other models generally agree on this setup. The second map shows the 2 meter dewpoints progged for the same time period, along with the lifted index. Obviously there should be no major concerns as far as lack of moisture is concerned. But once concern that may limit the potential here is similar to what happened back on Friday. Note the white circle I have placed on the 500 mb map. Right now, models show this lead impulse taking some of the "energy" away from the second system back in the southern Plains. I put "energy" in quotes because it's an over simplification, but the net result is that this lead system again weakens the 850 mb gradient, and we wind up having to wait until later in the evening to get the low level jet to crank again, and with it being tucked close to the parent trough coming out of the southern Plains, it would seem to imply that the tornado threat would be limited mostly to a 2-3 hour window, and storms may wind up clustering rather quickly after that. SPC has highlighted an area basically from New Orleans to Jackson, MS eastward into the Southeast in their day 4 assessment, though my guess is that will wind up needing to cover all of LA and MS. Greatest threat to me looks to be in LA, MS, and AL, and I could see this being a moderate risk day at the present time, but of course this far out will need to be refined as the event draws nearer. SPC also highlighted a risk this weekend in parts of OK and TX into the lower Mississippi valley, but this hinges on how much moisture can get back into the region in the wake of the Thursday storm, so will have to assess this one later on.

Maps referred to above:

Severe Weather Threat Today... In My Backyard!

Occasionally I get to write about weather in my own area, and today is one of those days. It's a tricky situation (always is down here regarding severe weather chances), but there is a risk of severe storms in parts of Texas and over into Louisiana later today and tonight, and yes, a couple of tornadoes are possible. This morning's cold front pushed farther south than expected though, but is heading back north as I type, which means warmth and moisture is back on the increase in southeast TX. We already have a severe thunderstorm watch in central Texas, mostly for hail. What to watch for later is 1) How much does the low level flow increase? And 2) Does the cap erode in SE TX, allowing storms to root in the boundary layer? Models show the low level jet increasing to over 30 knots later this evening just to my east, which is sufficent to get severe storms. Along and to the west of the LLJ axis is where the best tornado threat should be, provided the cap weakens enough. I see SPC almost pulled the "moderate risk" trigger here, and I can see that, but I feel that, given concers about the cap, a high end slight risk is the way to go. Sunshine has poked out here though, so we'll see what happens late afternoon into early tonight, which is when "prime time" would be.

A more significant outbreak of severe weather is still possible Friday and Friday night in far eastern TX into AR, LA, and MS. I still find it hard to imagine such a strong upper level storm like the one that is coming out of the Rockies (which will be a hefty late season snow producer from eastern Colorado into KS, OK, and parts of MO) can clash with such a warm, moist air mass without some fireworks. My guess right now is that SPC will go moderate risk in tonight's day 2 outlook for this event. As mentioned yesterday, this threat carries into the Southeast Saturday, still with some tornado potential.

And now we have a few models that show another storm around the middle of next week which could be a severe weather producer in the same areas, along with another snow threat from eastern Colorado into Kansas and perhaps parts of Oklahoma. Lots to keep track of here the next few days, so stay tuned!

BTW, here is today's tornado risk map courtesy of SPC, which I have no major disagreements with.

More Severe Weather On the Way

Yesterday went about as I expected... not a huge outbreak, but unfortuantely I did read that there were a few injuries. Here are yesterday's reports:














Looking ahead, there is no rest for the weary, as severe weather season seems ready to take off as we move through the next couple of weeks. Each of the next few days we have chances for severe weather, all the way to Saturday. I don't want to downplay the next couple of days (which could include strong to severe storms in my own backyard tomorrow into tomorrow night), but clearly the most glaring feature on the maps the next few days is Friday into Saturday. The current system moving into the Midwest is not able to push far enough south to really "clean out" the warm, moist air mass in place, which will allow the late week storm to have a lot of "juice" to work with. Here is the GFS valid Friday afternoon, which is one of the more ominous model depictions:















That's a pretty potent upper level system coming out of the central / southern Rockies, which by the way will be an impressive snowstorm from Denver out into parts of Kansas and perhaps up into Nebraska then the Upper Midwest for this time of year. The GFS also has a sufficient low level jet in place across the lower Mississippi Valley. Take note also of the vort max shown over the TN / KY region. That is a key also, as subsidence in the wake of this feature may allow sunshine to maximize destabilization from eastern Texas into AR / LA / MS ahead of the main upper low, though again, this model solution is probably the most ominous, but all models show what could be a dangerous storm in these areas (again maybe down toward me, though capping usually squashes the threat here for the most part... we'll see), though some other models do not depict much of a low level jet in place. While the GFS may be overdone, it's hard to see how such a system at 500 mb wouldn't generate enough of a LLJ for some severe weather (you don't need a 40+ knot LLJ anyway), especially with the warmth and moisture in place. Anyway, can't really get too specific yet other than this, but everyone from eastern Texas across the South will need to keep an eye on this, and the threat may extend into the Southeast Saturday.

Longer term, numerous models show a trough more or less anchored in the means near the Rockies, so we probably are not done with severe threats after this week, provided enough warm, moist air stays in place. We also may see a trough hanging around off the Northeast as well, but if you recall the image I posted a long time ago (I'll have to dig it up again) that showed the "optimal" tornado pattern, you often see this. The reason is that such a setup leads to higher pressure in the East, with a south to southeasterly return flow in the middle of the nation, and this keeps low level flow backed enough to maximize directional wind shear. Bottom line... We probably will have a lot to watch in the next week or two at least.

Update on Severe Threat Today... More on the Way?

Couldn't update this weekend due to internet issues, but the threat today is still contigent upon the dynamics making up for a relative lack of moisture (50s dewpoints can be enough, but you'd like to see 60s for a bigger outbreak of severe weather). One thing that looks more favorable than when I posted back on Friday is that we should have more directional shear in the KS / OK area than what I was expecting when I posted on Friday. I have posted a map of the 0-3 km shear vectors, and what I want you to do is imagine a north to south oriented front from central SD down toward central OK. Notice the shear vectors in KS / OK are oriented more perpendicular to the front, which gives storms more of a chance to remain supercellular rather than lining out, as may be the case farther north where the shear vectors are more parallel to the front. This is something to keep in mind when making an analysis of severe weather. Having said all of this, I really don't have a big disagreement with SPC's outlook for today. While there are limiting factors, a moderate risk is okay, though I'd be okay with a high end slight risk as well, given the borderline nature of the event. I may need a post to deal with a potentially more significant event later this week (Friday into Saturday), as models starting to look a little more ominous in that time frame from the mid-lower Mississippi Valley into the South.

Maps below are the 0-3 km shear vectors valid this evening, and the SPC outlook for today.

Severe Weather Threat Early Next Week?

Things have been fairly quiet on the severe weather front lately, especially when considering how active the last few years have been so early on in the season. It remains to be seen if we ramp up activity later on, but we do at least have a threat on the horizon for early next week. I have presented a few maps below which you may refer too. All models agree on a fairly potent upper low coming out of the Rockies Monday, as shown on the first map below, which is the GFS 500 mb height / vorticity plot valid Monday afternoon. Notice a strong trough also though over the Northeast, which I think will limit the amount of time a solid return flow of Gulf moisture will be into the Plains to at least some degree. A month later in the season and this may not be nearly as much of an issue, but it is still late March.

The second map is also a 500 mb plot, but has the winds at that level rather than vorticity. Notice peak winds in the jet core coming into the Plains are over 90 knots, which is solid and easily can support a severe threat.

The third map below is the low level jet at 850 mb, which exceeds 50 knots in its core, again, well over what you need to see to generate strong to severe storms. Given the low level jet's intersection with the 500 mb jet over central Kansas, this would be a favored area for severe weather, provided enough moisture and instability is in place, which may be the limiting factor. The final map shows that dewpoints are expected to be mostly in the 50s, as opposed to 60s, which would be a more favorable environment for storms. Also, this return flow looks rather dirty to me, meaning clouds and light precipitation may cover much of the warm sector, limiting how unstable the atmosphere gets, and indeed models show the highest instability will be limited to a narrow strip ahead of the front.

So my guess is that we will have a few severe storms from central Nebraska into Kansas, Oklahoma, and north Texas, with a few supercells possible despite limited moisture content. The area at greatest risk to me would appear to be central Kansas if I har to pick a spot, with perhaps a secondary area in southern Oklahoma / north Texas as core of 500 mb jet punches eastward in the evening Monday. An isolated tornado or two cannot be ruled out in my opinion as initial storms form Monday afternoon or early evening, but the flow has a strong southerly component at all levels, and the instability axis is pretty narrow, so my guess is storms will "line out", or aggregate together in a linear fashion quickly, making hail and gusty strightline winds a bigger threat as the event unfolds Monday afternoon / evening. There may be a threat for isolated severe storms Tuesday farther east toward the Mississippi Valley, but should be less of a threat than on Monday.

Biggest Piece of Evidence Yet of Global Warming

This is perhaps the single most important proof that global warming indeed is occurring, but makes the case that perhaps we should let it continue a little longer first. :)













I received this in my email this morning. Nothing like a little light-heartedness on what is a rather dull weather day! Ooh but the GFS is ready to put the eastern U.S. back into the ice box toward next weekend (not this coming one) and beyond! Stay tuned!

Weather Doldrums

Haven't been around to post for a bit, but am back to the regular routine for now. This is typically the time of the year when we have to start turning our attention toward severe weather / tornado outbreaks as winter fades away. Winter indeed is fading away, but for right now we're not seeing any notable severe weather chances on the horizon. In fact, the weather is downright boring for the most part (yes, for most people sunny and warm is not boring, but in the world of a meteorologist, there needs to be something a little more exciting).

We did get some exceptional cooling into Texas last Friday through yesterday. In fact, if you go back and look at historical records, a co-worker of mine found that for the 3 day period of March 13-15, each day from Friday to Sunday ranks in the top 5 coolest days in terms of how low the daytime high was (the highs these 3 days were 46, 48, and 54 respectively). So it was definitely an impressive event for down here.

Elsewhere, we're still locked into a la nina base state overall, and in fact, forecasts for this week are now warmer in much of the middle of the nation than what was in the forecasts back on Friday, which is no surprise since it is here where a la nina spring tends to focus its warmth. You often will get cooling opportunites closer to both coasts. The global angular momentum isn't as low as it has been though, but it remains to be seen if this is a sign of the end for this la nina state. Most long term modeling is actually favoring more of an el nino look down the road (later this year), so figuring this out will be key in figuring out what goes on this summer, and for you winter lovers, what type of winter we may see next year. But let's not get too far ahead of ourselves here.

I do still plan on typing up a quick review of this winter sometime soon, and will talk about how things turned out versus the consensus forecasts. We'll point out the good, the bad, and the ugly. Perhaps during this weather "downtime" I can also go into some of the global teleconnections and what they mean, if there is an interest there.

Texas Chill... Still Not Done With Winter?

One of the more impressive features on the weather map is the strong front heading into Southeast Texas as I type this. I touched on this the other day, and showed one model which was predicting temperatures would stay in the 40s Saturday afternoon. This type of chill is becoming reality, and in fact it isn't out of the question that most of tomorrow, Friday, and Saturday is spent in the 40s. To many, this doesn't sound like a big deal, but down here, where normal highs are in the 70s, it is pretty wild, and may in fact break the daily records on Friday and Saturday for the coldest high temperature on that date. Oh and I haven't mentioned the cold rain to go with it. I'm hoping we can at least salvage a drier Saturday night into Sunday, but we'll see. Definitely looks mega-dreary tomorrow through at least Saturday afternoon down here, though to be fair, the rain is badly needed across Texas. Here is a current map (won't be current when many of you see this of course), which still shows some warm air in Houston, but not for long, as the chill cometh!

Next topic... Still unable to say the books are closed on winter. It remains a possibility that some wet snowflakes fly with that southern stream energy in the Lower Apps / Mid Atlantic (down into VA) Friday morning, though shouldn't amount to much with marginal temperatures. Only the mountains are fair game really for a small accumulation I would think, but something to watch. And then there is next week, as the European model wants to bring one final dumping into the East around the middle of next week, with a very amplified pattern, which I have shown below. Is this possible? Well, sure it has a chance, but the Euro model seems to be an outlier right now with this kind of amplification, so I wouldn't hold my breath on this, not that most people would do this anyway given it is the middle of March, but stranger things have happened! Really the same key would apply as has been the rule all winter... getting a slower / more amplified northern stream, and frankly, with AAM not jerking strongly in one direction or the other as of this writing, it is a tough call a week away. We got it to work out once... We'll see if luck can strike twice. Stay tuned!

Welcome to DST!

"DST" being daylight saving time, which I loathe, as it means my workday is an hour longer (no the computer models do not run an hour earlier to compensate for the time change). But alas, I won't rant too much about that minor inconvenience here!


Although there isn't much in the way of extreme weather to talk about in the near term, with the exception of the possible blizzard in the northern Plains in the next couple of days, we do still have some things to watch for. First is the chance for isolated severe weather in the Midwest the next couple of days, but it doesn't look like a big event, so I won't talk much about that. I will turn more toward severe weather though as larger threats come down the road, so stay tuned for that. I showed in my last post the big temperature contrast from the warm side of this week's front to the cold side, and it does still look like quite a reversal later this week, starting in the Plains / Midwest and spreading east. I also said I was watching a southern stream feature in case it can produce any wintry mischief (or fun, depending on your perspective) this weekend, and this is still on the table. Sure, it is a long shot, but somewhere from the Apps of the Virginias into the Northeast could see something out of it given the cold in place, if the feature can come far enough north. Most recent GFS run says to at least keep an eye out.

Yes, the GFS 6.5 days from now is not the most reliable, but hey, I said it's a long shot, and it is (though not impossible), but at this point is all we have to really watch in the eastern U.S.

Turning to my own backyard, I'm torn on this weekend. I have outdoor plans for the first time in awhile, and wouldn't you know it, it looks rainy, which hardly ever happens down here anymore. To make matters worse, it looks quite chilly for this time of year too. Some of the cold air coming out of Canada gets down here later this week, and at the same time, the southern stream feature in the Southwest (same one to watch in the east toward the weekend) comes out, and moisture "overruns" the cooler air at the surface. Typically, a southwesterly flow bring in warmer air, but in this case clouds and rain effectively trap cooler air in the low levels. Below is the GFS model's idea for Saturday afternoon. Yes that is 40s shown for most of Texas even in the afternoon, with the chilly rain to go with it. Yuck. This model may be overdoing the cool air, but right now I tend to think much of Saturday is spent no warmer than low / mid 50s down here. Good news is we need the rain badly, though I'd like it to wait a couple of days longer.

Back in the Saddle

Haven't been able to post for a couple of days due to my sick child, but thankfully that is better now so I'm getting back into the routine now where I can fully focus on weather (which is good since my job depends on it!). I'll try to get into some more interesting things late this week, like reviewing the winter, and of course looking ahead more.

This week is pretty interesting though in and of itself. There is a minor snow event for parts of New England tonight into tomorrow. We also have a lot of warm air from the Midwest (some severe weather today, which I haven't really had time to analyze) into the South that will battle (and lose out in many areas) to some very strong cold sitting to the north, which pushed south and east this week. Parts of Canada are looking at temperatures over 30 degrees below normal early this week! Below I have posted one model's prediction of temperatures by Tuesday evening, and you can see the battle underway.











That is 70s showing up in parts of the lower Midwest, and below zero up in parts of North Dakota! The Dakotas in fact will get quite a blizzard out of this. To most people, this isn't interesting since not that many people live there. Fine. But I will say that as this cold pushes east, a lot of folks especially from the Midwest to Northeast may be surprised by its intensity, especially given the warm start to the week in a lot of areas. This, by the way, is in response to the AAM spike I talked about a couple of posts back, which is temporarily taking us out of the la nina base state (yes I stole this whole "base state" talk from NOAA's Ed Berry, as I think it is a good way to describe things). Can we get a storm to arrive as the colder air is here for any late snow threats? Nothing definite is showing up on the horizon, but watch a southern stream wave next weekend that could pull some funny stuff from, say, Kansas to the Mid-Atlantic.

The nina base state I think should come back later in the month though, and models are starting to fall into line with this idea (maybe that should worry me given how bad they've been at times?). This nina state in Spring typically means warmer than normal from Central Rockies to western Midwest and down to Texas, though leaves a risk for coolings along both coasts. Going a little IMBY here (you weather board folks know what this means!), la nina base states in spring with a very dry Texas already in place do not please me when thinking about summer, but that is for another time.

Global Warming on Hold?

http://dsc.discovery.com/news/2009/03/02/global-warming-pause.html

Please read the above link. Back when I started this blog, I posted about how global temperatures have stopped rising, and opined that this halt in warming (perhaps even with some global cooling) could persist for the next 10-20 years given some of the climate shifts and odd solar behavior we are seeing. Well, it seems that this has dumbfounded some climate "scientists". I put scientists in quotes because I cannot figure out how some of the junk they say is even worthy of being called science. Consider a portion of what is shown in the article concerning the halt in the warming in recent years.

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"This is nothing like anything we've seen since 1950," Kyle Swanson of the University of Wisconsin-Milwaukee said. "Cooling events since then had firm causes, like eruptions or large-magnitude La Ninas. This current cooling doesn't have one."

Instead, Swanson and colleague Anastasios Tsonis think a series of climate processes have aligned, conspiring to chill the climate. In 1997 and 1998, the tropical Pacific Ocean warmed rapidly in what Swanson called a "super El Nino event." It sent a shock wave through the oceans and atmosphere, jarring their circulation patterns into unison.
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This Swanson guy is a climate scientist? So he mentions that large la ninas can lead to cooling, yet cannot find any explanation at all as far as what is going on. Hello! You might want to actually check out some actual data! Or we could just choose to ignore the fact that we are in the second year of a LA NINA, which was actually a pretty strong one last year. And the second paragraph above... the strong el nina jarred circulations into unison? That doesn't even make any sense, but since a supposed climate scientist cannot even tell we've been in a solid la nina, I guess nothing more should be expected.

At the end of the article, Swanson then states that this "halt" may go on for 30 years, but says "explosive" warming WILL resume thereafter! Gee, thanks. I'm supposed to believe that someone who apparantly cannot recognize a la nina, and admits to not having a clue what is going on right now somehow has what will happen 30 years and beyond all figured out. Forgive me for having no faith in this.

As I have said previously, the point is not that I doubt the role of human influence in global warming (some will read this and make that blind assumption). I think it probably is there. We just don't know if we account for 5%, 50%, 75%, or whatever. Until we have a better understanding of natural cycles (which this shows we obviously don't), there is no way to quantify our role in it.

Can We Close the Books on Winter?

The snowstorm the other day, while satifying many of the snow lovers along the eastern seaboard and even into the South, has left many people wondering, can we squeeze out anything else this season? Is the pattern still favorable as it turned out to be for this previous event? Well, truthfully, if you live south of 40N latitude, yes it is getting pretty late, though not impossible, as some storms of the past have shown. Farther north stays in the game much later of course.

Anyway, to the present... We are about to get an impressive warm surge into the East this weekend to erase much of the snowpack built up the other day. We could see temperatures reach at least 75 in Washington D.C, and perhaps flirt with around 70 in New York City. Even back to Chicago and Detroit should see temperatures reach the 60s. Certainly this will turn most people's thoughts to Spring, but we do have another interesting situation atmospherically going on currently. Note the first map below. It is the tendency of the global angular momentum (AAM), and is currently off-the-charts positive. We have been in the tank negatively for awhile, and recall negative AAM is a nina-like state, while +AAM is more typical of a nino state. And yes even in a la nina or el nino you can get temporary AAM cycles that support an opposite pattern. This spike upward in tendency indicates we may do just that. This should lead to addition of westerly flow coming off eastern Asia, and push the upper ridge currently in the north-central Pacific closer to the West Coast. This would lead to chances for colder air intrusion again farther east. Indeed, the second map, showing the model prog for 10 days away shows this ridge west / trough east alignment, and for those of you who know your climo, you can see this is a more nino-is look than nina. Also there is a hint of blocking in the Atlantic too, which can sometimes occur at times as a result of AAM spikes reverberating through the global atmosphere also.

So we have a favorable setup to get some colder air back into the pattern after the weekend into early next week warmth. Will it be enough? Well, as mentioned, it gets tougher this late in the season, so all you can say is that it gives you something to watch for. Then we have to consider how long this pattern would last. Given the tendency of the atmosphere to want to jolt back toward the nina side of the AAM charts recently, the window of opportunity may not last long until we can say we are waltzing into Spring (keeping in mind up north can stay in the game into April).





AAM Tendency



















Day 10 Model Forecast

March Comes in like a Lion

March 1st marks the beginning of meterological Spring, though obviously the atmosphere is in full winter mode, moreso than it has all season long for some areas, in fact! For snowlovers in the eastern U.S, this has been quite a storm. While in some spots it was slow to really get cranking last night, many, especially in Virginia up to the D.C. / Baltimore areas, woke up this morning to more snow than they probably would have expected upon going to bed. But if you were tracking the upper level features of the storm, this should have been expected. I have a map of the 700 mb level (about 10,000 feet above sea level) below (first map), and have drawn in a red "L" to show where the upper low was located at this level with the storm this morning. The black arrow shows the approximate direction the low was tracking. The green shading shows the moisture content (specifically the relative humidity at that level). Notice the moisture along and the west of the track. It is in this zone where "surprises" can occur given a strong enough system. A common rule of thumb is that you want to be near or just west of the 700 mb low track, which worked well with this storm given how intense it was.


The second map below map is at the 500 mb level (approximately 18,000 feet above sea level). The colors here show vorticity, which is a measure of spin in the atmosphere. Ahead of strong areas of vorticity, called "positive vorticity advection", you have stronger rising motion. Behind them you have sinking motion, or "negative vorticity advection". With sufficient moisture in place, the lift from an incoming vorticity maximum (vort max for short) causes clouds and precipitation. I have circled the main vort max with this storm. The track of this feature was similar to that of the 700 mb low shown in the first map. So if you look at this map, you see the areas of greatest moisture content, which coupled with the strong vort max, led to bands of very heavy snowfall just to the west of the track of these features today. These bands typically can produce several inches of snow in one area, and very little not too far away, which is what I tried to show with the sharp cutoff in snowfall on the forecast map.

So hopefully you had a chance to not only enjoy the storm, but learn from it as well. The idea here is that even if a storm like this is a slow starter, don't ever give up on it if you are just west of the forecast track of the 700 mb low with a strong upper level vort max in play. You can often get a pleasant surprise in such a setup. Once the storm is totally done, I'll look at verifications versus the forecast issued yesterday.

Final Call for Snowstorm

I pretty much outlined what all had changed and allowed this upcoming storm today into tomorrow to come farther west and up the coast in yesterday's post, so will keep this simple and just get to the final call map. The main thing is to tighten the gradient from 1-3, 3-6, and 6-12 zones. This ups the forecast to 6-12 inches in the big cities of the East Coast. You won't have to go too far though before amounts drop off quite a bit. As is always the case with these storms, confidence is lowest close to the edges due to the gradient. It will be cold and windy behind the storm too, with temperatures a good 15 degrees below normal (upper 20s to low 30s... teens for some interior areas in Northeast), so bundle up! Snow map below. Light blue is 1-3", darker blue is 3-6", and purple is 6-12". There can be local amounts to at least 15" within the 6-12 zone as well, though hard to pick out exactly where, so did not throw in a 12+ zone on the map here. Enjoy!