…the weather-related postings in this corner of cyberspace will slow way down. But first we have to recap winter and take a look ahead at the spring and summer seasons.

Winter isn’t officially over, of course. On the calendar, we still have more than two weeks of winter remaining. But the meteorological start of spring is March 1, and as we had predicted for weeks around here, we are in the midst of an abrupt shift from predominately cold weather to predominately mild weather. We still have all the botany cold snaps left ahead of us (Dogwood Winter, Blackberry Winter, etc.), but the worst is definitely behind us.

So, let’s recap how we did. Here’s what I said back on Oct. 1 in the winter preview:

Average to slightly below-average temperatures, on the whole, with more days featuring below-average temps than days featuring above-average temps. Our weather will be dynamic, with a number of storm systems. Thus, the wetter-than-normal conditions will continue, but the surplus won’t be as significant as it has been this summer (which saw a foot of rain more than normal here on the Plateau). We will have a 75% chance of seeing total snowfall exceeding 10 inches. There will be a few nor-easters that will turn into a blizzard or two for the Northeast. Closer to home, there should be enough potential for at least a couple of blockbuster winter storms. But where they set up at is the question. Will they go west of us (as they have the past two winters)? Will they go east of us? South of us? Only time will tell.

• Average to slightly below-average temperatures: Fail. For a large swath of the Mid-South, it was one of the ten coldest winters on record. In Oneida, December was only slightly below normal (35.1°; normal is 36.5°). But January was almost five degrees below average and February was a shocking eight degrees below average. The three-month average temperature in Oneida was 30.9°. That’s well below our 30-year rolling average in December-February, which is 35.7°.

• Dynamic weather with many storm systems: Money.

• Wetter than normal but with a rainfall surplus that is less than last summer’s: Yes again. We received 13.85″ of precipitation from December through February. Our average is 13.54″. (I question the accuracy of those numbers, which are reported by the NWS. I think we likely were a little wetter than that.)

• 75% chance of seeing total snowfall exceed 10 inches: Yep. Most of the northern Cumberland Plateau saw around 20″ of snowfall, the most since 1998.

• A few nor-easters that turn into blizzards for the Northeast: Go ask folks in Washington D.C., Philadelphia and New York City what they think of this winter. (I realize Philly and D.C. aren’t considered “Northeast,” but they’re northeast of here, aren’t they?)

• Potential for a couple of blockbuster winter storms but where (in the Southeast) will they set up: True. We had a Mississippi River-to-the-Appalachians snowstorm back at the end of January that was the highest-impact winter storm Tennessee has seen since probably 1988. A couple of significant winter storms pounded western North Carolina. Another winter storm brought snow to places like Montgomery and the Florida panhandle, which is extremely unusual.

So, winter was pretty much as expected, if a little colder than expected. Now the attention shifts to spring. With a diminishing El Niño still impacting our weather, a subtropical jet that has been very active all winter long, and a storm track that is slowly shifting northward, you have to figure that we’re going to see our fair share of thunderstorms this spring.

Severe weather experts and hobbyists are gearing up for a somewhat delayed but highly anticipated severe weather season across the Deep South, and that is where much of the strong-to-severe stuff east of the Mississippi River should take place this spring. But Middle Tennessee and West Tennessee can certainly get in on the action as well. Here on the Plateau, terrain typically protects us from the roughest severe weather (with the exception being Crossville, the Plateau’s own Tornado Alley), but as last May’s Fairview tornado showed us, no where is truly safe from severe weather.

The southern branch of the jet stream should begin to slow down in the weeks ahead, and in fact we’re already seeing that start to take place. That means less cloudy and rainy weather overall than we saw in January and February. All in all, the spring should be a relatively active one from the Midwest to the Deep South. It also may be a prolonged one. There are signs that this spring season (in regards to polar air trying to penetrate the continental U.S. and the creation of storm systems that swing from the Midwest to the Great Lakes regions) could last until well into May.

Summer set in with a vengeance last year, creating miserable conditions across much of the Deep South during a pre-4th of July heat wave. After that, however, a cold and rainy summer set in. We’ve gone from one extreme to the other in the last three years (oppressive heat and drought in 2007 to flooding and cool temperatures in 2009).

Signs this summer are somewhat muddled at this point. Those that are discernible point to this summer delivering neither of those extremes, but we should be closer to a repeat of 2009 than to a repeat of 2007…although the most impressive heat, compared to normal, will probably be back-loaded and come at the end of the season rather than being front-loaded as it was a year ago.

While the ENSO stage drifting into El Niño last summer undoubtedly contributed to the cool conditions, other theories suggest that a lack of sunspots and ash polution from volcanic eruptions north of the mid-continent helped to contribute to cooler-than-average temperatures. If either of those theories is correct, it stands to reason that cooler weather will prevail into this summer, particularly if the lack of sunspots are to blame.

On the other hand, if the ENSO were to trend into negative territory (setting up La Niña), that would tend to point towards warmer-than-average temperatures this summer in this part of the country. Many models now showing the effects of El Niño dissipating by spring’s end, with a neutral ENSO being the general rule as we head into summer. If this proves correct, we may well have a very normal summer…much similar to what we saw in 2008. If I were guessing, I would say this summer will feature slightly below-average temperatures and slightly above-average precipitation, but not to the extremes we saw last summer.

From a National Weather Service-Morristown discussion this morning:

BY THE WEEKEND WITH A RIDGE BUILDING IN, A RETURN TO MORE NORMAL (EVEN ABOVE NORMAL) TEMPS LOOKS LIKELY, ALTHOUGH CLOUDS WILL ALSO ADVANCE IN FROM NEXT SYSTEM OVER THE HORIZON. STILL, SHOULD THIS ACTUALLY HAPPEN, IT WILL SEEM LIKE A HEAT WAVE. SPRING MAY HAPPEN EVENTUALLY, AFTER ALL. CROSS YOUR FINGERS.

It is indeed going to be nice by the weekend. The NWS in Nashville is indicating that high temps may approach 70 in the southwest portion of the Mid-State.

And, of course, what have we been saying? From Feb. 24:

Still, my uneducated gut feeling is that we’re going to go from talking about possible snow storms to talking about possible thunderstorms by the end of next week, as we see that abrupt change from winter to spring that has been alluded to.

Okay, okay. Enough horn-tooting.

I’ve had March 7-10 circled for a while now as when spring would make its presence felt in East Tennessee, and have mentioned those dates on a couple of posts in recent days. The latest GFS computer model data seems to agree. The model output statistics (MOS) from today’s midday run of the GFS paints a high of 56 in Oneida next Saturday, and even warmer on Sunday of next week. The raw model data isn’t quite as warm, but does indicate temperatures in the 50s each day.

We’ve seen a few 50-degree days this month and last, of course, but it never lasted. The difference this time around is the warmth should be here to stay. We may see high temps in the 40s a couple of days the following week, but our days with highs in the 30s should be pretty well done, and days with highs in the 50s should be the norm rather than the exception beginning next Saturday.

When we say goodbye to February this weekend, the month will end colder (relative to normal) than the month of January.

How’s that? January had the bitterly cold temperatures to start the month; the longest stretch of sub-freezing temperatures since the World War II era. But we had some nice weather later in the month that will probably go down as our warmest temperatures of the entire winter season. February, by comparison, has been consistently cold. We haven’t had much bitterly cold weather in February; aside from a temperature of 5° on Feb. 1 and 6° on Feb. 2, our coldest temperature all month was 14°. But the cold weather has been long-lasting. That goes without saying; it’s why we’re all jonesin’ for spring…there has been no reprieve. We hit 60° only once in February (62° on Monday). And, remarkably, we hit 50 only twice (Sunday and Monday). In an average February, we hit 50° a total of 14 times!

So, while January was actually colder than February at face-value, February actually turned out to be more impressive, since the higher sun angle typically means warmer temperatures in February.

Here are the numbers: With two days to go, our average temperature in February has been 29.1°. In a typical year, the average temperature in February is 37.0°. By comparison, the average temperature in January was 28.7°. The typical average in January is 33.5°.

Along the same lines: Consider that stretch of temps below freezing back in early January, the longest stretch of sub-freezing weather since World War II. It was a sign of what an epic winter season this is. But here’s a statistic that is even more telling:

The Memphis office of the National Weather Service has compiled the record number of consecutive days without hitting 70° in that city. Memphis has currently been 103 days without hitting 70° (Nov. 15 was the last time temps reached 70° in Memphis). That’s good enough for ninth all-time in Memphis, dating back to 1875 when records-keeping began. Tomorrow will make 104 days, and that will tie for eighth all-time, with a stretch of 104 days in 1936.

What’s even more impressive is that of all the stretches of sub-70° days in the Top 10, none of them occurred more recently than that stretch of days in 1936. The record is 140 days back in 1915. Second is 133 days in 1931. Third is 122 days in 1877. Fourth is 121 days in 1912. Fifth is 114 days in 1885 and 1886. Seventh is 111 days in 1908.

So after tomorrow, Memphis will have officially gone longer without reaching 70° than any stretch since 1931, which is quite remarkable.

And all this follows one of the coolest summers we’ve had in years. So the question that arises next is what will the summer of 2010 bring us? More below-average temperatures?

In other news, the University of Tennessee is awarding Al Gore an honorary doctorate degree. (Sorry; I couldn’t resist.)

There hasn’t been a lot of changes since yesterday with what looks to be a major winter storm the first half of next week. One thing that is very notable, however, is that the GFS computer model has decided to rejoin the party.

The GFS is a domestic numerical weather guidance model, operated by NOAA. It, along with foreign models in Canada and Europe, are the most noteworthy models, at least where winter weather is concerned. For days, the Euro and the Canadian models have been mostly consistent with a low pressure system near the Gulf Coast on Monday and Tuesday of next week that would produce a winter storm for parts of the Southeast. The GFS, however, has consistently pushed this storm deep into the Gulf. By yesterday morning, it had pushed the storm nearly all the way to Cuba.

But this morning’s 0z run of the GFS reversed course, and the GFS is now far enough north to throw precipitation into East Tennessee once phasing occurs after the low has crossed northern Florida. The 6z run of the GFS from later this morning wasn’t quite as far north and west as the 0z run, but far enough that I think we can safely say the GFS has decided to abandon the deep Gulf idea with this storm. That means the GFS, Canadian and Euro are all on board with a low pressure system coming out of the Gulf and tracking up the Eastern seaboard. That increases confidence for a major winter storm for some parts of the South next week.

For now, it continues to look like our area on the northern Cumberland Plateau will be right on the edge of the system. In fact, it isn’t inconceivable that it could miss us all together. As I said yesterday, my gut feeling is that this storm impacts areas south and east of us. But it’s looking increasingly as though parts of East Tennessee, perhaps a line from Chattanooga to the Tri-Cities, or a little further west than that, could receive snow from this system. But all three models are now showing at least light snow reaching our area, so it wouldn’t take much of a shift to the north and west at all to bring us more snow.

To that end, the National Weather Service has increased precipitation chances for some areas of East Tennessee. The forecast at Oneida remains for a 20% chance of precipitation. Across the Southeast, some weather forecasters are scrambling to introduce snow chances to their forecast for next week, as confidence has increased with this system.

I was not impressed with this system just a couple of days ago. However, it’s looking right now like this could indeed be the major winter storm that has looked like a strong possibility for a while now, as Ol’ Man Winter shows up for his last hurrah before giving way to spring. If temperatures cooperate, places like Atlanta and Asheville could see a significant winter storm out of this, particularly Asheville and other places in the Carolinas, which could be absolutely blasted by this system.

Much will change between now and Tuesday. Around here, it’s going to be interesting to watch and see if this storm can continue to pull northwest, or if phasing between the north and south branches of the jet stream occurs earlier than currently projected by the models.

Global numerical weather models continue to indicate a major storm system developing in the Gulf of Mexico early next week. The question remains how far north that storm system will be able to trek, given some weakening blocking across eastern Canada. There are some indications that East Tennessee could receive some decent snow accumulations from this system.

That isn’t likely to make the school teachers or the students happy. Local schools are out today with an inch of snow on the ground, the 16th day they’ve missed due to snow this year. Can you say goodbye spring break?

As far as the weather forecasts, the National Weather Service in Morristown is currently predicting only a 20% chance of rain next Tuesday, with a high of 40. The NWS in Nashville is forecasting a 20% chance of rain and snow on Tuesday, with a high of 43.

I feel very confident in this: If we see precipitation Tuesday, it will not be in the form of rain. It will be snow. We can count on that.

The question is whether we’ll see precip. We’ve talked seemingly forever about the possibilities of a late-season winter storm impacting parts of the Southeast. But as we said yesterday, there’s considerable modeling data showing that the storm will stay suppressed to our south.

The GFS continues to show this storm suppressed well into the Gulf of Mexico. In fact, the latest run of the model takes the low pressure system almost to Cuba…obviously, that isn’t a solution that’s going to bring snow to the Southeast. But the other two major models that we follow, the European (ECMWF) and Canadian (GGEM) show this storm following a path along or near the Gulf Coast. Yesterday morning we noted they were slowly trending towards the GFS. But ever since then, that trend has been just the opposite. They’re still waffling on the exact placement of the low, and in fact the overnight runs of each model showed the low a bit further south than the previous run, but they aren’t suppressed like the GFS.

In reality, neither model shows this system going far enough north to be a big impact for much of Tennessee. For now, it continues to look as though cities like Atlanta and Charlotte are going to receive the brunt of this system. But we might have to throw in cities like Chattanooga and Asheville as well. Current modeling data indicates a big hit for north Georgia and the Carolinas, as well as parts of Alabama.

But it’s worth noting that the latest run of the ECMWF does throw enough moisture this far north and west for some decent snow accumulations on the northern Cumberland Plateau. So it would appear that East Tennessee isn’t out of the woods yet as far as this system is concerned.

If the ECMWF and GGEM are correct, this is indeed going to be a major winter storm for some areas. The question is where and how much. And that’s a question that isn’t close to being answered.

When the energy to our south phases with energy to our north will help determine just how powerful this storm is and whether or not it impacts our neck of the woods. That is a detail the ECMWF and GGEM are still trying to resolve, while the GFS appears to be out to lunch on this system. My gut feeling is that this one is going to impact areas primarily to our south. But there’s no way to say that for sure right now. I wouldn’t be too surprised if it continued to trend in a direction that would bring big snow to East Tennessee.

Still watching a storm system that is set to track through the Gulf of Mexico early next week, but it’s looking more and more as though this won’t be the significant snow-maker that it had once looked like it might be. And that could mean our snow is finished in much of Tennessee. (Do I hear anyone complaining? I didn’t think so.)

The National Weather Service does have slight precipitation chances in our forecast for early next week, due to the continuing uncertainty with this storm system, but it looks more and more as though it will stay well to our south.

What’s going to happen: The storm system is going to track across the southern U.S. and into the Gulf of Mexico, where it will get its act together as a major storm. We’ve talked on this blog for the past couple of weeks about the potential for a major late-season storm as the Gulf waters warm and blocking over the northern latitudes of the hemisphere relax. The storm system is indeed going to form and it is going to be strong, but right now there is pretty consistent modeling that suggests this thing will not take a classic Miller A storm track through the deep south and up through the Carolinas, which is what I was expecting.

The GFS has been very consistent over the last few days with keeping this storm suppressed into the GOMEX. Initially, however, the European model and Canadian model were still showing a more northern track and a big hit for parts of the Mid-South, and both of those models have out-performed the GFS this winter. However, both of those models are slowly but surely trending towards the GFS.

The relaxing Arctic Oscillation should allow this storm to travel further north…but a stronger than anticipated area of high pressure over eastern Canada may prevent that from happening. It looks to retrograde in the days ahead. The question is whether it will retrograde quickly enough to allow this storm to take a track through south Georgia and up the Carolina coast rather than crossing Florida somewhere around Tallahassee. Right now, almost no model thinks that will happen.

There’s still time for it to swing back in our direction, but if I were placing bets right now, I’d say that places like Birmingham, Atlanta and Charlotte will see snow…if anyone in the South sees snow. The GFS wants to keep almost all the moisture from this system out to sea, but the other models aren’t ready to take it that far yet.

Meanwhile, winter continues for at least one more week. Next week shouldn’t be too cold, but it does look like we’ll be stuck in the 40s for highs most days, and we may be a little colder than that early in the week. Remember, our temperatures are usually climbing quickly this time of year. In an average year, our high temperature today would be 51 degrees. By March 10, the average high has climbed to 55 degrees.

Beyond that, signs are muddled. The models want to push a couple of storms in the extended range west of the Appalachian mountains, which should signal a return of milder temperatures by the end of next week, somewhere in the March 7-10 time frame. We’ve mentioned on this blog that the Arctic Oscillation should begin to plod back towards negative territory over the next couple of weeks, which is a good sign that spring-like temperatures are on the way. The latest trend of some models makes it less certain that the AO will enter positive ground. And the North Atlantic Oscillation is being modeled to stay in negative territory through at least mid-March, so it’s hard to say with certainty that winter is over.

Still, my uneducated gut feeling is that we’re going to go from talking about possible snow storms to talking about possible thunderstorms by the end of next week, as we see that abrupt change from winter to spring that has been alluded to. And with no more storms on the table between the Gulf special early next week and the end of the week, that could mean that we have indeed seen our last accumulating snow in Tennessee if the early next week storm does indeed stay south of us.

That doesn’t mean we’ve seen our last snowflakes flying in the air, of course. A stormy pattern in the weeks ahead could mean we’ll see rain changing to snow flurries or snow showers as cold fronts pass through the region. That’s fairly common in Tennessee in mid-to-late March and even early April. Remember, we don’t typically see our last frost or hard freeze until well into April. But, for all intents and purposes, it looks like someone may be able to stick a fork in winter in about 10 days.

And then it’ll be time to look towards the expectations for summer: Will we see a cool and somewhat wet summer, like last year? Or a return to oppressive heat like we saw in 2007? Only time will tell…but there are a few things that might shed a little light on what we can expect.

Still watching the potential for a blockbuster winter storm the first half of next week as the Arctic Oscillation begins to relax and we barrel towards spring.

We’ve been talking for a while now about the potential for a significant late-season winter storm to impact the eastern U.S., specifically parts of the Southeast and the Mid-Atlantic. Most global models are now showing a major low pressure system developing in the Gulf of Mexico early next week, and most of the models are taking a decidedly winter approach with the storm.

The GFS, European and Canadian models are the three medium- to long-range models that are worth following, and all three are locked in on this potential system right now. There are other models showing similar scenarios, but those are the three important ones. A literal interpretation of some of the latest GFS runs show the storm staying too far south to impact much of Tennessee…in fact, today’s midday run of the GFS keeps the heaviest precipitation contained in the immediate coastal area of the Gulf. But it’s way too soon to be trying to nail down who gets snow and how much. At this point, it’s all about the bigger picture: A major storm system rising out of the Gulf as the month of March begins. This is right on the cusp of 7-day forecasts for the National Weather Service and area TV meteorologists, so I suspect that we might begin to hear some chatter about the potential for next week as we go through the next day or two.

I would be remiss not to point out that there is plenty of climatological precedence for this storm to take a track west of the Appalachian Mountains instead of east of them, which would make a decided difference in our weather. Instead of cold and snowy, we would be mild and rainy, with the threat of strong-to-severe thunderstorms further south, if such a scenario panned out. Right now, there isn’t much model support for such an equation, and it’s probably more likely that this storm is a winter storm than a thunderstorm-maker. In fact, the bigger picture considered, it might be more likely that it stays suppressed in the Gulf and doesn’t provide any precip to Tennessee than it is that it goes north and brings us a mild rain. But a west-of-the-Apps/lakes cutter scenario is just one of a couple that is on the table, and there is some historical evidence to back up that idea.

Either way, it looks like March is going to come in like a lion. And, either way, we’ll continue to bang this drum: It looks like an abrupt season change is upon us as we go through March. We’ve talked about this extensively, but it’s probably worth repeating. We typically see a transition period during the month of March, with a lot of weather like we saw this weekend but with plenty of cold air mixed in. I’m not saying we won’t see a cool day here and there as we go through March and early April, but once the pattern breaks down—whether it’s the first week, second week or third week of March—I think we’re going to go from predominately winter weather to predominately spring weather in a hurry. If the subtropical branch of the jet stream stays active after that, there’s no reason to think that spring won’t be a hectic one in the weather department, with several severe weather risks for the Southeast region as a whole.

Beautiful weather in East Tennessee this weekend has a lot of folks crossing their fingers and hoping for the best: Winter is over.

But you don’t even have to go beyond the 5-day forecast to find winter’s return. The National Weather Service’s forecast calls for a high of 35 degrees on Thursday, with lows of 20 Thursday morning and Friday morning, as colder air surges back into the region.

Raw data from the GFS computer model is colder than that, suggesting a high of 27 on Thursday, with a low of 12 Thursday morning and a low of 17 Friday morning. That’s probably over-done. With no snow cover, it’s a little hard to believe that we’ll be quite that cold under an end-of-February sunball.

Still, winter isn’t over by any means. A meteorologist in the Knoxville market actually said a few days ago that models were showing no more cold shots. That was a dangerous statement, and the forecast for the middle of this week shows why. As we’ve been saying here for some time, winter isn’t going to end until something happens to break down the pattern in the northern latitudes of the hemisphere.

The good news is that the Artic Oscillation, which is a measure of blocking in the Arctics region and has been severely negative for a while now, is modeled to sharply retrograde over the next two weeks. A negative AO typically means increased winter weather chances for the South, so if you’re looking for the first sign of an end of this cold and snow nonsense, look at the pattern in the Arctics. Meanwhile, the North Atlantic Oscillation, a measure of blocking in the northern latitudes on the opposide side of the continent, looks to stay slightly negative for a while now.

But as we’ve been saying for a while, the AO entering this pattern-change phase will bring increased chances for a significant winter storm. When it occurs and where it occurs are questions that are impossible to answer, but I still think the potential for an end-of-winter major winter storm is as good or better this year as the last several years. Right now, the time-frame that all eyes are on is next Monday and Tuesday, March 2-3. The GFS and European models are indicating a strong Gulf of Mexico low pressure system that could impact a sizable swath of the eastern U.S.

A literal interpretation of this morning’s 0z GFS shows a Miller-A classic that would provide a notable amount of precipitation in East Tennessee. The model says mid-level temps would be below freezing–supporting snow as the primary precipitation type–but surface temperatures would be above-freezing until the end of precipitation. But that’s eight and nine days out; there’s no point in paying too much attention to the details. The main thing to note is that a storm is on the table.

That’s no guarantee, of course. A week ago, we were looking at the end of this week, Feb. 26-27, as the date to watch, and there looked to be potential for two late-season winter storms in the South (Feb. 26-27 and March 2-3). The models were showing a major storm impacting the region in this time frame. Subsequent model runs changed. The storm still looks to develop, but whether it will impact our region at all is very much in doubt. The GFS keeps it well south of us and never fully develops the system. Last night’s run of the Euro model actually shows a wintry weather setup for our area, but no one is going to put very much stock in that scenario right now.

Likewise, this storm for early next week could change as well. There’s at least an average chance that it becomes a “lakes cutter” (takes a track on the western side of the Appalachians and heads for the Great Lakes region), which would mean milder temperatures and rain for us, with thunderstorms further south. In fact, such a scenario with that low amplifying sufficiently could actually start to collapse the pattern over the northern latitudes and help to usher in spring even though it would pull in colder air behind it.

After a high of 48 degrees today, the GFS model output statistics are indicating a high in the 50s through Monday before colder weather sets back in, topping out at 56 degrees on Sunday. If that happens, it will be the first time this month that we’ve hit 50 degrees in Oneida. In a typical February, we hit 50 degrees about 14 days during the month. The high temperature recorded by the National Weather Service in Oneida this month is 44 degrees, back on Feb. 2. The last time we hit 50 was back on Jan. 24, when we reached 55 degrees.

The NWS is under-cutting the GFS numbers but does forecast highs in the low 50s on Saturday and Sunday.

The NAM model output statistics are even warmer than the GFS, suggesting a high soaring to 58 degrees on Sunday. If that were to happen, it would be the warmest we’ve been since Jan. 16.

For what it’s worth, the last time Oneida hit 60 degrees was Dec. 15, at 61. Christmas Eve was close, at 59.