Winter Storm Watch

Mar 24, 11:27 PM

UPDATE 6:08am FRIDAY

I just analyzed the new 6Z data and we have a consensus amonst the models! Both the U.S. and European models have converged on a track that looks bullish for snow in our area. As a forecaster this is what you are looking for,especially when you are within 36 hours of the event. Hopefully this will continue with subsequent runs from now til we wrap things up.

The screaming message here is that our storm should track in such a way that we get into the snow late morning Saturday and keep it going for about 12 hours. While the snow will be very wet and slushy, it will likely accumulate at least 6” in parts of our area. The heavy nature of the snow should limit blowing and drifting but we may get some late Saturday and Saturday evening as temps. cool and the winds peak near 30mph.

Here is some graphical data for you to enjoy. Remember I will have regular updates here througout the day. I will also have a video briefing on the site later this afternoon…approximately 1 to 2pm.

UPDATE 11:08pm…….

UPDATE 11:08pm

I have had a chance to look at the new 0Z models and I must say I was miffed by the outcome. The WRF guidance was further northwest and that was a trend I hoped to see as it had been consistently the outlier with a much further southeast track. Then the GFS rolled out a track further southeast that shifted it’s heavier snow band a bit further in that direction. What I was hoping for was consistency and obviously that was not the case. What to do, what to do?

As I look at the scenerio, I can make a case for either model. The GFS had been rock solid and I trust it far more than most models. We are now getting closer to crunch time meaning the solutions on all models should be coming into closer agreement. I have to give the GFS heavy consideration but this is the first time it has shown this trend so I am not sure if it is on to something or if this was just a bad run.

On the other hand, the wrf is a very high resolution model and it does quite well within 48 hours. Since it made a shift in its guidance the same situation exists, is it exhibiting a trend or is this a one time aboration. Frankly, I don’t have a clue.

One thing is for sure, the 6Z runs which hit about 5am will clearify this issue. I guess the best thing for me is to try and catch some sleep and get at this fresh on Friday. Ah, the joys of forecasting. Why do I do this!

I’ll be back with you Friday with the latest. Until then ride the wind.

T. Swails

UPDATE 7:30pm THURSDAY-MODERATE RISK….

UPDATE 7:30PM THURSDAY
The 18Z runs are hot off the press and we are getting closer and closer to a significant wet snow event. Overall track and Intensity has come in about as expected and if you have been on my site the last 3 days, you know what I’ve been saying all along, things are gonn’a get wintry Saturday. I’m now getting pretty confident of the big picture, now we start getting to the fun part (hard for some forecasters) of fine tuning and putting together the details. While winter storm watches have not been issued for our area they have been hoisted in Missouri. If tonights runs come in strong they may be officially flying here by morning. How exciting!

Here are some grapics which are nice and fresh. I will have new date and charts out around 10:30 tonight as the 0z runs trickle in.

Track and area of heavy snow potential

Surface map with heavy snow band over Mississippi

HPC RISK OF A 4” SNOWFALL

HPC RISK OF A 8” SNOWFALL

HPC RISK OF A 12” SNOWFALL
Well, there you have it. Some serious proof that were have issues on the way. You can always dream of a “White Easter”.

UPDATE 10:30am THURSDAY

Just a quick show of some NWS graphics and text on what they are thinking in terms of snow Saturday. I will have new data in later this morning with my own oppinions added at that time.

DAY 3 Discussion from HPC…
SOUTHERN PLAINS/LOWER MISSOURI VALLEY/MIDWEST…
EARLY SPRING SNOW STORM WILL BE IN FULL SWING WITH BLIZZARD
CONDITIONS ACROSS TEXAS PANHANDLE…MUCH OF WESTERN
OKLAHOMA…SOUTHWESTERN KANSAS AND A SMALL PORTION OF NERN
NM…SATURDAY MORNING AND AFTERNOON WITH A SWATH OF HEAVY WET SNOW
TRACKING THROUGH AND EXITING…SOUTHERN/EASTERN KANSAS AND
NORTHEAST OKLAHOMA BY LATE SATURDAY MORNING AND EARLY SATURDAY
AFTERNOON WITH THE SOUTHWESTERN FRINGE OF THE DEFORMATION/COMMA
HEAD PIVOTING SLOWLY ALONG THE KS/OK BORDER. SPRING STORM BRIEFLY
INTENSIFY IN THE MIDWEST ON SATURDAY WITH LARGE AREA OF H85-H5
FRONTOGENESIS AND FORCING DEVELOPING SNOWFALL ACROSS THE NORTHERN
PERIPHERY OF THE COMMA CLOUD PRECIPITATION SHIELD AND DEEP
CONVECTION RE-IGNITING ACROSS THE SOUTHEAST. THIS DEFORMATION AXIS
ALLOWS FOR SNOWFALL TO BRIEFLY STREAK OUT ACROSS NORTHERN MISSOURI
AND EASTERN IOWA ON SATURDAY EVENING. THE HEAVY…WET SNOWFALL
FORECAST FOLLOWS THE SLOWER…ECMWF/NAM AND H5/H7 FORECAST
TRACK…WITH SNOW GENERALLY DEVELOPING ALONG THE I-44/I-57
CORRIDOR BY SATURDAY AFTERNOON/EVENING ACROSS MO/SRN IL THEN
SHIFTING INTO NRN IL…SATURDAY NIGHT AND INTO LOWER MICHIGAN BY
SUNDAY MORNING. DAY 3 SNOWFALL FORECAST ANTICIPATES A BROAD AREA
OF 4+ INCH SNOWS ACROSS NORTHEAST OKLAHOMA…SOUTHEAST
KANSAS…CENTRAL MISSOURI AND NORTH CENTRAL ILLINOIS.

WEDNESDAY NIGHT……

Well the new data is in and for the most part, my thinking is on track. The 0Z model runs take a vigorous storm right into e/central Illinois on Saturday and that puts us in a very vulnerable spot for heavy wet snow. The big issue with this system all along has been the amount of cold air and how that relates to the track and the all important rain/snow line. Here are some graphics to show you what I am seeing as of Midnight.

First and foremost here is the surface depiction of the surface low as it slides through Illinois. Notice the big area of blue over eastern Iowa and parts of Illinois. That is the 6hr. precip totals which near 3/4 of and inch. If that was all snow under 8:1 liquid ratio that would be about 5-6” during that period alone. Add on another 1/4” in the next 6hrs and you are looking at total snowfalls of 6-9” (assuming the model is right)

You may be wondering how you tell rain from snow? Well, the next chart is the 850 analysis and it shows the freezing level about 1000 feet above the ground. As a rule, despite temperatures on the ground that may be 34-38 degrees, snowflakes will be large enough to reach the ground since since the freezing level is low enough to keep the flakes from melting before reaching us. Note how the 850 freezing line is to our southeast. That should mean all the precip that falls during that 6hr. period would be snow. (again, assuming the model is right) Another thing that will likely help in snow production is dynamic cooling which will help draw colder air to the surface from the clouds above.

Once again, you can see from this satellite image that the storm is still a long ways away off the Pacific Northwest coast. Data will get better later Thursday as the storm comes onshore. If I am looking at the same scenerio this time Thursday night I will be raising the red flag and digging out the shovel.

From the home office, that is how things look tonight. Stay tuned to this blog for more updates as the storm starts to show its hand.

Ride the wind,
T. Swails

TUESDAY MARCH 25th………

Just as spring is about to explode, winter is saying….whoa, not so fast big fella, I’ve still got some cards to play. In fact, if the charts I’m seeing tonight are right, winter is holding a hand that that is a long ways from folding. What do you say we talk “potential” snowstorm.

OK, we begin with a satllite shot of the Pacific and what you see here is a nice chunk of energy that is about 4 days away. This is the genesis of the storm that I am referring to. It is slated to drop into the southern plains and then hook on up towards the southern tip of Lake Michigan. If that track verifies, that is dead on for heavy snow in our area. Of course, it is very early in the game and I am reluctant to get too confident in this solution. The Pacific ocean is vast and until the storm is onshore and we get model output from the data rich USA, I reserve the right to tell you this is far from a slam dunk. However, model trends have to this point been very consistent in this general path and that is comforting to a forecaster.

My next graphic is a 500mb analysis which shows the closed upper air feature that is the storm on Saturday. This is the core of the energy that is progged to move from the Pacific to this position the next 96 hours. Note the storm is located to our south in Missouri. That is critical because it puts us in the cold sector and that is absolutely imperative if we are to get in on the good snows. A chart like this is notable because a closed circulation shows an impressive storm structure aloft that yields tremendous lift and precipitation potential. It also signifies strong surface development which is the low pressure we always talk about when we track these types of storms.

My last chart shows the storm tracking to our east and the deformation band that is right on the top of our area. If this were to hold temperatures would be cold enough from dynamic cooling to produce heavy snow rates of at least 1” per hour. Thundersnow would most likely occur which could up the snowfall rates even more. The surface low drops to 985 millibars which believe me is a real ripper and that should crank out some hefty winds.

So there you have it, if the weather charts have their way tonight we will have ourselves a heck of a weekend snowstorm. Unfortunatley, we’re still days away from this thing and much can change. One thing I can say for certain is that this is the kind of storm that trips my trigger and I will be all over this thing. Stay tuned to my blog as I will be giving you the latest insights on trend and outcomes.

Ride the wind,
T. Swails

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