Snow storm summary

Saturday evening and night, a swath of snow associated with an area of low pressure lifted northeast out of the south, and passing through south central WI. The band of snow was on the northwest side of the low, dropping anywhere between 3 and 8 inches of snow across parts of Minnesota and Wisconsin. Below is the snow total map, although some areas near the metro didn't receive as much as what is being shown. The map does, however, give you an idea of where the snow did set up, which was a bit further north than previously forecast.



With a fairly sticky snow, and pretty much no wind, the snow was able to stick to tree branches with ease, creating quite the winter wonderland when people woke up Sunday morning. Here are a couple pictures I snapped.






Other than a few shots of cold air coming in, the weather appears to be going back to that boring state yet again. These shots of cold may be able to squeeze some flurries out, but at this point no major systems in the works (other than the GFS bringing in something a week and a half away, but it is too far away to be credible at the moment).

Winter Storm!

Well after months and months of pure boredom, a weather system of some significance is making its way towards the area, poised to drop the first decent accumulating snow of the season. While this particular system will fall well short of any "Storm of the Century" headline, it will certainly test drivers winter driving skills. At this point, surrounding weather service offices as well as local forecasters are going with a band of 4-7 inches of snow across the area, which certainly seems reasonable given the moisture available for this system to work with, and the fact that the system will move through at a decent clip. Below is a map of snowfall potential, as well as the current watch area, courtesy of the NWS office in La Crosse and Chanhassen. Again, overall this map looks good given what the models have shown at this point.



Current headline map (posted 12:46am Saturday)



The current storm track takes the low from northern Missouri to a near Madison, WI and off to the northeast. This low also looks like it will have a decent tap into the Gulf of Mexico, as shown in the 850mb moisture transport. Below is the GFS forecast map from the Penn State e-wall site.




Taking a look at Bufkit, both the NAM and GFS show an area of dry air that will have to be overcome before snowfall can begin. If this particular dry air can be overcome sooner than models show, amounts could potentially be higher. If it takes longer for it to saturate, then amounts will be trimmed. At this point, Bufkit data from the GFS and NAM both show full saturation for EAU sometime between 4 and 5pm Saturday evening, so I would expect the snow to begin in that time frame. Below are images from the 00z run of the NAM and GFS. You'll notice omega values around -10 overlapping the snow growth zone, so fairly good dynamics showing up with this. I would expect snow rates to be approaching at least an inch/hour for a few hours time, and this could be the bulk of our accumulation.

GFS:



NAM:



While a watch is up now for the area, I fully expect this to be upgraded to a warning, maybe not so much for snow totals, but the fact that it is the first system of the season, and the NWS hopes it will force more caution on people. I also expect perhaps a tier or two of counties surrounding the warning area to be given an advisory, again just to keep people aware of what's going on. This system should keep us in all snow here in Eau Claire, with areas further south near La Crosse will probably see more mixing potential. So again to summarize, it looks like a decent band of 4-7 inches of snow is possible for the area, but keep in mind if some convective bands can form, as was the case a few weeks ago near St. Cloud, there could be amounts higher than 7 inches. However, given the very isolated nature of these bands, they are near impossible to forecast right down to the city. Stay safe out there everyone!

Stubborn "Cut-Off" Low

What a gloomy past 5 days it's been around the Northern Plains/Great Lakes region. The culprit...something those in the weather world call a "cut-off low". A cut-off low is an area of low pressure that is removed from the main jet stream. Usually systems move along the jet stream, and are here and gone within a day or so. On occasion, areas of low pressure become removed from the main jet, therefore stalling out until a front comes through and pushes it along. This has been the case with this low, which really started affecting our weather since last Thursday. Below is an image of where the low is, and where the main jet currently is (way up in Canada).



It does look like, however, that some relief is finally on the way as a trough/cold front looks to sweep across the area, and will therefore push the low off to the east. It is still a good 48 hours away, so we are probably going to have to deal with the clouds and gloom through the day Tuesday, and likely even most of the day Wednesday before the clouds break. Below is an image of where the low is forecast to be, with the blue lines showing the trough that will push the low off to the east.



That trough will also deliver a shot of cooler air, with the European model being more aggressive than the American models, but it will certainly look and feel like fall. We will warm back up though, with the CPC predicting above average temps in their 6-10 day outlook.

Can wildfires enhance instability for thunderstorms?

Recently in my boredom, I thought I would take a peak at the visible satellite loop in northern Minnesota to see if the smoke could still be seen. Looking at the loop a couple times, I did spot the smoke, but there was something else that I noticed as well. It looked like thunderstorms were developing right over where the smoke was. At first, I thought it was a weird coincidence, but after watching the loop a few more times, it looked like the clouds kept billowing and storms kept developing over that same spot. At that point I thought to myself, can the heat from wildfires actually provide extra instability to the atmosphere to help with thunderstorm development? I know I've seen mini tornadoes in the fire of wildfires, but wasn't sure if it went beyond that or not. So, I'm interested in any input from people on their thoughts. Did the fires assist in thunderstorm development, or was this just a mere coincidence. Below are some stills I got of the visible satellite images.

Hurricane Irene...too much hype?

As Hurricane Irene, or at least what's left of her, continues to wind down, it would seem as though more than just death and destruction were left in her path. There seems to be some debate going on in the weather world, with people wondering if there was too much hype and build up as Irene developed from a tropical wave, to a tropical storm, and eventually a hurricane, and as her track became more defined. I personally am not a fan of hype, and looking back at things now I would agree that there was too much hype...to an extent.

I am a firm believer in advanced warning when it comes to hurricanes, as I would hope everyone else is. The sooner a person knows what is potentially coming towards them, the sooner they can plan to get out of town and to safety...unless of course you work in the TV or storm chasing world, in which case you drive to town, and away from safety. I think regardless of the amount of hype that went into some of the national headlines, the cities along the east coast did things right. They got out of town, away from danger, and hoped for the best. That is the whole point of having an advanced warning system. Now today, people are saying that Irene was a weak storm, and didn't live up to "expectations". At least 21 people have lost their lives because of the storm, and a large part of the northeast will be experiencing flooding for days, perhaps even weeks if more systems go through there and drop more rain. The feeling I am getting from people is that they expected more death and destruction. Usually people should be rejoicing that Irene didn't come through as forecast, yet it sounds like some are disappointed. In my eyes, it is better to over prepare than it is to under prepare. When there are that many people potentially at risk, you just don't take chances. You get out, and hope for the best. The fact that many people did evacuate very easily may have saved lives. I realize there is the "cry wolf" factor, in that people will hear a warning later and ignore it because "forecasts with the last one were bad and it ended up weakening a lot, so we are staying." My thoughts on that are, that regardless if it was expected to be a Category 4 storm or a Category 1 storm, people are set on what they want to do. Hurricane Katrina is a prime example of that. People were warned days in advance that this was going to be a massive life threatening storm, but some just insist on staying either because they are stubborn and won't leave, or think that it won't be as bad as predicted. Days later, those people are on their rooftops, angry that no one is there to help them. Don't get me wrong, I feel horrible for those people and what they went through, but they were warned to get out. Yet every time there is a hurricane headed for the US, we see interviews on television of people who just won't go.

Forecasters may be taking a lot of heat by some, because Irene didn't live up to their "expectations"...but let me ask you this. What if forecasters said this wasn't going to be a big storm, but then a Cat 3 crashes into New York, and hundred of people die because they didn't think it was going to be bad. Again, the heat would be on the NWS, and local weather outlets. Sometimes it is just a lose/lose situation.

In closing, the next time a storm is heading for the east, people still need to take things seriously. Plan for the worst, hope for the best...that is something I was taught, and still think about today. Just because one storm happens to not pan out as exactly precisely projected, doesn't mean the next one would do the same. I would just caution national outlets on their headlines that they use. I realize it's all about ratings and getting web clicks, but I think that can easily be done without adding too much sensationalism. HURRICANE IRENE EXPECTED TO TRACK UP THE EAST COAST, PACKING STRONG WINDS AND FLOODING RAINS. Boom...that gets the point across. It's honest and straight to the point. "DAY AFTER TOMORROW" STORM TO MOVE IN TONIGHT...ummm really? Ok, so that headline wasn't used, but I believe the movie reference was made at some point. I guess we'll see what lessons were learned from this storm once the next tropical system takes aim at the east/northeast US. We may not have to wait too long either, as some models are spinning up what may end up being Katia, and the second hurricane in this Atlantic season. Stay tuned!

Dangerous situation unfolding across Kansas, Oklahoma, and northern Texas

HIGH RISK OF SEVERE WEATHER FROM SOUTHERN KANSAS, THROUGH OKLAHOMA, AND INTO NORTHERN TEXAS. SEVERAL STRONG, LONG TRACKED TORNADOES POSSIBLE TODAY, ALONG WITH VERY LARGE HAIL AND DAMAGING WINDS.

15z surface analysis shows a low pressure system in the panhandle of Oklahoma, with a stationary front extending northeast across central Kansas, through Iowa and into northern Illinois. A cold front is extending down from the low, and bending around through the panhandle of Texas. A dryline extends south of the low, out in front of the cold front, and will be the focus of today's storms.



The combination of surface heating, high dewpoints, and strong wind shear will lead to an outbreak of supercells capable of producing very large hail, damaging winds, and several large tracked tornadoes, with the area within the high risk the most likely to see these tornadoes. Below are the list of risks, issued by the SPC at 1630z.

RISK

TORNADO RISK

HAIL RISK

WIND RISK

Here's a peak at the first tornado watch of the day, covering the higher risk area for today, with the probability of seeing several strong tornadoes being quite high.



Taking a look at current meso analysis shows significant tornado probabilities climbing quite high, and are expected to continue to increase as the day wears on. 0-6km bulk shear is also climbing rapidly across western Oklahoma, and will continue to move east, and increase as the low level jet strengthens later this afternoon. SPC is forecasting explosive development of cells, with very large hail being the initial threat. As that LLJ continues to strengthen, the tornadic threat will also increase.

Enhanced Tornado Index

0-6 Shear

850mb GFS forecast

People across these risk areas need to pay attention to the changing weather conditions, as several more watches will likely be issued as the day wears on. Any cell that forms will become supercellular rapidly, and has the potential to become tornadic.

Severe weather outbreak possible across parts of the south

POTENTIALLY DANGEROUS SITUATION EVOLVING ACROSS OKLAHOMA AND KANSAS.

Today's greatest focus for severe weather will be from south central Kansas into parts of central and eastern Oklahoma, per the SPC's 06z outlook, which is shown below.



The 06z surface analysis across the south shows a low pressure system in southeast Colorado with a cold front extending down through the Oklahoma and Texas panhandles, and a warm front stretched through central Kansas. A very potent dryline also extends down in front of the cold front into Texas, and will be the focus of today's severe weather. Note on the analysis map below the extreme difference in dewpoints, pre (dewpoints in the upper 60's) and post (dewpoints in the teens and low 20's) dryline.



As the day goes on, the low pressure system will deepen and move slowly to the northeast across central Kansas, while swinging dryline across southern Kansas, Oklahoma, and Texas. 24/00z GFS 30mb dewpoints (see below) clearly show the contrast in dewpoints, and the focal point for thunderstorm development. By 7pm CDT, the low pressure area should be in west central Kansas, with a warm front extending from central Kansas, and off to the northeast across northern Missouri, with the cold front bending back into the Texas panhandle, and dryline extending south of the low through southern Kansas, Oklahoma, and Texas, also seen in the image below.





GFS's 500mb 18z forecast map (see image below) shows a negatively tilted trough with two vort maxes moving with the trough. These vort maxes will assist in the triggering of severe thunderstorms throughout the afternoon and evening hours.



GFS's 700mb 18z forecast map (see image below) shows moderate wind speeds of around 25 knots in the area of concern, increasing to 35-45 knots as the day goes on. These winds are expected to generally be out of the south/southwest. These winds, combined with winds out the southeast at the surface, should provide enough turning in the atmosphere to create supercells capable of dropping large hail, and potentially long tracked tornadoes. The SPC (also posted below) has, therefore, issued a 30% risk for tornadoes, with a hatched risk showing the potential for significant (greater than EF-2) tornadoes.





A quick peek at the GFS's 850mb 18z forecast map shows weak to moderate winds, in the range of 20-30 knots across northern TX, eastern Oklahoma, and southern Kansas, but increasing to 35 to 45 knots by 25/00z. (See images below) These winds will be out of the south, which will help to draw up a significant amount of moisture (see 30mb dewpoint map above) This moisture will add a lot of fuel to the fire, and will also lead to some serious flooding concerns, as these storms will be going over areas that have already been hit hard by severe weather over the past few days.

18z forecast map

00z forecast map

Something else to note is the amount of CAPE (convective available potential energy) this system will have to work with. By 00z Wed, the GFS is showing an band of MLCAPE between 3500 and 4000 J/kg, with CINH (Convective Inhibition) rapidly erroding. These high CAPE numbers, along with little CINH will allow for rapid, explosive development of supercells, and fairly low freezing levels will allow for very large hail to develop. The SPC has highlighted this threat as well with a 45% risk for hail, and have hatched that risk to signify the potential for significant hail.

CAPE

CINH



As the evening and night wears on, the SPC is forecasting for the cells across Texas and along the dryline to begin to diminish as capping takes over, however a continued wind threat may be seen as storms further north continue to press off to the east. SPC has a 30% risk for wind highlighted to cover the initial wind threat, and lessening the threat as it moves east. (See graphic below)



People need to be aware of what is going on through the day if they live in these higher threat areas. It has already been a very active year across the south, and is proof that these storms, even with all the current technology, can be deadly if a person isn't prepared. Keep those NOAA weather radios on, and make sure they have good batteries in them.

The winter that won't go away

This winter was predicted to be a long, snowy winter, and to this point it certainly has lived up to its hype. Almost 70 inches of snow here in Eau Claire with places in Minnesota approaching the 90 inch mark. Most of the snow had melted a couple weeks ago, before another system came in, dropping anywhere between 6 and 12 inches of new snow, and pretty much gave us back what we had melted. Again, we warmed up, and again this snow melted, and again a potent storm system came through and dropped 6-12 more inches of snow across parts of central Minnesota and western Wisconsin. As this snow pack had melted, the moisture from the snow eventually ran into the rivers, and put some rivers and streams over their banks. Potential record flooding is possible along several points of the Minnesota and Red River Valleys during this spring, and it doesn't look like we will be seeing a long enough stretch of dry weather to cut down on the flooding potential.

This week, fortunately, is looking somewhat quiet, with just a few precip chances for the end week. At this point, it doesn't appear to be anything significant. Surface temps should be well above freezing during the day with temps dropping a bit below freezing overnight Thursday into Friday. Saturday looks like a nice day with temps in the upper 40's to near 50. Sunday into early next week continues to be the time to monitor, as a low pressure system passes south of the area, and a fetch from the Gulf. Showers and thunderstorms could break out across southern MN and western WI during this time, with the potential for half inch or more of rain. This system is a ways out, so plenty can change between now and then. Models haven't really locked a solution yet, so there is little certainty on what will potentially happen. The central plains and parts of the south will need to monitor this as well, as severe weather could be possible from Missouri on south through Texas on Sunday afternoon/evening. Pretty strong cap may be in place, but again this is a ways out so lots can change. Something else to note is some of longer range forecasting tools are hinting at the potential for another shot of below normal temps as we get further into April. I'm really hoping this changes, and we could get into some warmer temps to get rid of the remaining snow, and push us into summer and thunderstorm season. Until then, we'll have to deal with this roller coaster that we in Wisconsin (or Minnesota) call spring.