Category Archives: Story

A pattern change

For most of the spring, the country has been plagued by a broad, slow moving wave right across the center of the country. It’s been spectacularly unpleasant, with Arctic air lingering over the continent of North America for the last couple of weeks, introducing record lows and several late season snow storms.

Fortunately, the tide seems to be turning. The mean jet flow is finally forecast to shift north, indicating that the chilly air will finally be pent up where it belongs, at least for the long term. As you can see with the forecast jet stream analysis for Monday, the continuous stream lies just north of the Canadian border.

Thee will still be a threat for a cold air invasion late next week, but not nearly on the scale that we’ve seen for the beginning of the month, as the pattern has become much shorter in wavelength. Any period of cooler air will be briefer, and won’t be able to sneak as far south.

The jet is retreating, along with the cold air, but it isn’t switching pattern immediately. The northern part of the country is simply moving closer to normal, rather than suddenly moving above normal.

Spring storm shows we are only 1 month behind now

Yesterday, Anthony discussed a spring system that’s headed for the Plains, and he focused particularly on the threat for snow in the Upper Midwest. Run to run, it’s been pretty speculative as to where and how much snow would fall. I tend to hedge towards the lower end of the spectrum, of the opinion that more warm air will surge north because April Gosh Danged 12th. Some people are more pessimistic, and they have every right to be, given some of the model runs and how depressing this spring has been so far.

There is quite a bit of uncertainty over the amount of snow or where it will happen, but the storm is showing signs of looking extremely springlike in at least one manner. We are looking fairly locked in for a broad severe weather outbreak this weekend, as the cold front moves across the  south central US. Already there is an enhanced risk of severe weather, and I would be surprised if there isn’t a moderate risk as we approach the valid period.

The outlook for moderate storms presently stretches from Kansas City to College Station for Friday. A sure sign of trouble ahead is the expectation of severe weather on the 3 day outlook, which has an outlook for a triangle from Clarksville, TN to Tallahassee and Lafayette Louisiana. The threat for severe weather is far more tangible than the snow expected.

There will be no primary threat out of this system – The trifecta is possible, from tornadoes to strong winds and large hail, thanks to the layout of the storm, with a tightly wound area of low pressure to the north to a strong, active cold front in the south.

Having a bunch of strong thunderstorms in the southern US, tied to an active snow storm is a very typically March pattern, and is a sure sign of the seasonal transition. The problem is that the season should have already transitioned at this point.

Spring Storm On Horizon

Last week I wrote a post about a strong spring system that simultaneously dropped several inches of snow across the Upper Midwest while further off to the south, a severe outbreak swung from the Mid-MS River Valley into the Ohio Valley. A similar setup is shaping up for this weekend, with the chance for even more prolific snowfall totals.

An strong cold front is set to push over the West Coast during the day Wednesday bringing plenty of rain to the Pacific northwest down to the Sierra’s as well as high elevation snow. As the system works into the Great Basin, a new area of low pressure looks to develop and push through the Central Rockies while it intensifies, which is also expected to bring high winds to the Intermountain West. As the low pressure pushes out over the Central Plains on Friday, it will tap into plenty of Gulf moisture for it to transport northwards. This looks like another heavy snow setup for the Dakotas into the Upper Midwest while the MS River Valley gets targeted for some severe weather. While the models are still a bit too far out to get an accurate idea of just how much snow the north will get, it looks like SOMEwhere is going to get hit with a bulls-eye of 12-18″. Where will it land? Stay tuned!

The cold builds west

The story of the spring so far has been the relentless cold, marked at times by strong systems moving through the northern US, leaving unseasonably snowy tracks through the region. This story, however, was confined largely to the part of the country that lies east of the Rocky Mountains. Points to the west were actually in the throes of warm, even unseasonably hot weather.

A great example of that is Phoenix, where Tuesday’s high will be 100 degrees. That’s significantly warmer than normal. We’ve been stuck in a standing wave pattern,  with a trough in the west and a high amplitude ridge in he west.  Expect that to change by week’s end.

A trough waiting just off the coast will move inland around Thursday, bringing quite a bit of precipitation to the western US. That will certainly be a big part of the story as the weekend approaches, but don’t miss out on this other component: Most of the country will see temperatures that are below normal, at least for the weekend.

Snowy and Severe Spring Startup

We’re a full fortnight into Spring now and people are itching to get outside and start doing fun outdoor things. Mother Nature, however, especially for us in the Upper Midwest, refuses to let us escape Winter’s frigid grip. A strong low-pressure system working through the Central US over the last 24 hours has brought a swath of snow from the Dakotas through MN into WI and continues eastward through the Great Lakes. Areas around the Twin Cities got 6-10″ today and continues to pile up in WI. Meanwhile, on the warm side of this system, strong to severe thunderstorms rumbled their way from Indiana/Ohio all the way down to coastal TX. Strong winds accompanied severe storms from Columbus, OH down to Eastern TX into MS, and while that was the most widespread severe effect from this sytem, over 110 reports of large hail were also reported.

Storms like this aren’t rare for early Spring however. On this date in 1974, a similar but stronger low pressure system was making its way through the Central US. Over the Upper Midwest, a swath of snow fell across MN and WI accumulating up to 6-12″ (7.3″ specifically in the Twin Cities). What this system is more well-known for, however, is the widespread tornado outbreak that hit the Midwest down to the Deep South. 148 tornadoes happened over a 24-hour span in what became known as the Super Outbreak, the largest tornado outbreak on record in the US. This would remain the US record until the 2011 Outbreak which more than doubled that number! Luckily, no historic tornado outbreak will develop from this system, but we do have to be wary of all kinds of inclement weather this time of year!

Nope, it’s not spring yet

We had just a pinch of warmth over the last couple of days across much of the country, and given a look at the calendar, one might be led to believe that we are on the cusp of spring, green grass and blooming flowers.

Nope!

A cold front has swept through the Great Lakes tonight and is starting to move towards New England. A broad upper level trough is going to settle into the eastern 2/3 of North America, and perturbations moving along the jet trough will lead to a few fairly intense storm systems moving through the center of the country, all the while pulling more cold air south. A blocking pattern in the north Pacific will mean that this could go on for a while.

If you thought spring was here, winter disagrees

Birthday Week Rains

Tomorrow is my birthday! Luckily for me, the next couple of days look to get quiet up here in the Upper Midwest, with temperatures pushing towards 50 in the next couple of days. Beautiful days indeed! However, from the Southern Plains to the Ohio Valley and Deep South, the next few days are going to be anything but beautiful. A slow-moving frontal system draped from the Mid-MS River Valley down into the Southern Plains will be the focus of showers and thunderstorms tomorrow, and with training cells quite possible, some areas look to get 2-5″ from southern Illinois to north Texas. Wednesday is going to be more of the same, just shifted eastward slightly over KY/TN back into northeast Texas. Thursday continues the deluge as it shifts into east Texas to the Southern Appalachians. Overall, a swath of 4-6″ of rain is possible from Eastern Oklahoma/North Central Texas eastward to southern Kentucky/Tennessee. I guess that whole thing about April Showers is starting a smidge too early.

First moderate outlook followed by 4th Nor’Easter

As I’m sure you have heard, the east coast is getting blasted by yet another strong area of low pressure thanks to the standing long wave parked across North America. Things are a little different this time, because with spring arriving today, temperatures were a little bit warmer, and there was simply more energy available for the system to feast on.

Seeing the set up, the SPC put together their first moderate risk outlook across northern Alabama yesterday. A long track super cell indeed set up, and the forecast verified very well.

At least one large tornado moved through the area, and there was large hail between Huntsville and Birmingham. In particular, the college town of Jacksonville, Alabama (home of Jacksonville State) was hit by a tornado. Fortunately, the school is on break, and not only was the campus lightly populated, but not a soul in the entire state or even in Georgia, where the storm later ventured, was injured. That is a credit both to the forecasters and media, but also residents of the region heeding their warnings.

Warnings continue now up and down the east coast, but these are for rapidly accumulating snow. The good news is that the storm won’t bring nearly as much wind, but the orientation of the upper level jet and the cold  pool, as well as a nearly stationary inverted trough mean that snow will be persistent and long lived. It looks like the most snow with this round is going to fall in the Philadelphia area.

I think this storm, given the warmth in the region, has a chance of underwhelming on snow totals, but even if it does get to the 10 inch range in Philly, that’s good enough, right?

The threat for nasty weather will shift to the west coast, and eventually the center of the country. A well deserved dome of high pressure is going to set up in the area later in the week.

The Northeast is in the crosshairs again

New England has been battered in the last month or so by two massive Nor’Easters and the forecast is for another big storm coming mid week next week. Why has it been so relentless this winter?

This winter has been dominated by a long waved pattern. Frequency is lower if waves are longer, which is to say that the pattern slows way down when waves are longer. The wave in reference here is the upper level jet stream, which is analyzed here:

There is a lot of action on this map, which might make one believe that the pattern should be much more active, and there are indeed a few areas to watch (The Rockies, and the lower Mississippi Valley, for example) in the next couple of days, before we return our attention to New England.

The problem is that pink, stronger jet streak running from the Great Lakes to the north Atlantic. That is tied to a broader trough that is more easily identified when you look from the North Pole.

Here, you can see the north to south jet off the west coast. Over time, the jet streaks over the North American continent have or will continue to dissipate, leaving a broad trough over the US, with a strong exit region along the East Coast, wherein the exit region is the most conducive for cyclonic development.

Compounding things is a strengthening ridge in the north Atlantic, which will threaten to maintain the wave over North America for even longer. This is a summer or winter like pattern, but as we head towards spring, the differential heating across the planet will ease this logjam, and New England will start to come up for air.

Forecaster of the Month: February

February is the shortest month of the year, and it was just as action packed as it always is. I mean, not as active as March has begun, but there were some big snows, especially in the upper Midwest, and some severe weather down in the southern Plains and Lower Mississippi Valley. They weren’t the headliners that the recent Nor’Easters have been, mostly because of where the nasty weather occurred, but it all provided its own forecasting challenges. In the end, it was Victoria-Weather that was able to overcome those challenges and win the monthly title