Potential Snowstorm- Tuesday-Wednesday

As I mentioned last week, there is still a potential for a decent snowfall for parts of southern Michigan, NWOH, and northern Indiana. However, this setup is much more complex than originally expected. I've been updating everyone on the chat bar to the right of this post for several days now.

What has happened is a very strong upper level low (seen below) cut off from the main trough. This has stayed fairly stationary today, but is expected to move generally northeast throughout tomorrow and overnight.

As this upper low moves to the northeast, a surface low is expected to track from the TN valley to the Ohio/PA border:

Now, usually this is an ideal spot for a significant winter storm for Western OH, North/West IN, and Southeast Michigan. However, this will not be the case for this storm. Due to the fact that this upper low comes from the southeast, plenty of warm air has already settled into the area. However, this is a very, very shallow layer of warm air, located within the lowest 150mb of the atmosphere. However, there are already questions with model predictions, because high temperatures today struggled to be reached.

Now, lets look at a few certainties for tomorrow:

1.) Precipitation will be almost all rain tomorrow morning/early afternoon
2.) A surface low will track east of the area, right around Erie PA
3.) The models have trended east in the past couple days.

Now, here's a few uncertainties:

1.) Will snow changeover to rain? If so, when?
2.) Where will the snow first begin to fly?
3.) Will ground temperatures limit accumulations?
4.) Is the cold/warm air still not forecasted correctly?
5.) How much snow will areas receive?

Unfortunately, many of these questions will not be answered until the event itself starts. There is still a decently large model spread between NCEP models and Global Models. The NAM has continued to rapidly shift to the east, giving Toledo 5" of snow based on raw BUFKIT numbers. The GFS, while also continuing to go to the east, still has north-central IN to Flint, MI as the heaviest snow swath.

What really throws a wrench into things is the ECMWF and UKMET. By far the most consistent models for this storm, the ECMWF has also slowly trended east, but much further east than any NCEP model. Shown here, and on AccuweatherPro ECM maps, the ECMWF has over 1" (liquid equivalent) of frozen precipitation for Fort Wayne/Extreme NWOH into SEMI. Based on accupro maps, the ECMWF shows a widespread 4-8" and even up to 10" plus in some areas. Below is an image from the link shown earlier this paragraph:

Another thing to note is the GGEM/RGEM from Environmental Canada (Their version of the NWS) show an earlier changeover to snow than the GFS/NAM, suggesting a bigger snow potential as well. The UKMET also appears to show something similar, while the GFS Ensembles also look to produce more snow than the operational.

For those looking for an easy forecast, shield your eyes from this storm. This is an extremely complex weather system, that likely will throw surprises at us even as we come ever closer to this possible snowstorm. Local meteorologists, NWS offices, and the HPC all seem to have different opinions, just as the models do. There are a few wildcards to watch, such as the amount of dynamic cooling that occurs in heavier precip, as that could cause an earlier switch to snow. Also, ground temperatures are going to be interesting, considering the amount of moisture in the soil right now. Sometimes heavy snow can accumulate quickly on a once warm and wet surface, and other times it does not matter.

I wish I could have a definitive answer for those reading this, but I honestly don't. My gut says that Fort Wayne to Flint gets the heaviest snow, likely over 4", while those east and west of there get slightly less. My preliminary forecast (take with a grain of salt) is 3-7" for NWIN/Southern MI, while NWOH gets 1-3". This could change a lot over the next 12-18 hours, so don't expect this to be a perfect forecast. I will likely be on and off the live chat for much of the night, so if you have any questions, don't hesitate to ask.

Anyways, this looks to be an exciting 36 hours!

Long Range Look

With beautiful weather going on currently, I want to take a look at what's going on in the long range. Currently the GFS and ECMWF show a weak but large system moving into the southern Great Lakes region by Wednesday afternoon, with light rain and cooler temperatures. Rainfall amounts will most likely stay below 1/2", with higher amounts possible in Southern Ontario. Most of the rain should be out of  Ohio/Michigan by Friday afternoon, while rain lasts until Friday night in Ontario, especially futher north towards Toronto. This low pressure system will also bring some cooler temperatures to the region, with temperatures staying below the low 60s (below 17C).

These cool temperatures look to persist during the rest of the weekend into next week. According to the models, this isn't the big story.

The big system to watch would be about 8 days from now (Monday-Tuesday timeframe). Both the ECMWF and GFS show a strong system developing in the Ohio Valley and tracking just east of Toronto. Below are a few images from the GFS:

Now, this is what you would expect to be a classic snowstorm for most of northern Ohio, eastern Michigan, and southern Ontario. Unfortunately for snow lovers, this is still October. But to see a storm like this early in the season is fairly promising. What's interesting is that if you were to only look at 850mb Temps/Precip/SLP, you would expect this to be a snowstorm. 850mb temperatures are below freezing, but the surface is well too warm for snow. If this continutes to be shown on the models, then expect a cold rain and a lot of rain, but just like the winter season, storms in this range are fairly unpredictable. It's always a cool sight to see this early in the season, but it won't be a snowmaker here. This is just the first of many storms to watch this fall and into the winter.

Even if this storm does not end up nearly as strong as models are currently showing, the telleconnections support at least a quick period of below average temperatures with the deep trough coming out of Canada. I like the idea of a brief spell of below average temperatures to end the month, although I believe it will warm back up starting November.

Weather for the Week

After an absolutely gorgeous past 4 days, the weather is expected to get rainier over the next few days.  Although temperatures should remain cool, showers and thunderstorms are expected from Wednesday to Friday.  Showers and storms should develop and move east-northeast into  Northwest Ohio by late afternoon tomorrow.  These storms are not expected to be severe.  However, some isolated severe weather is possible further south towards Dayton, Columbus, and Cincinnati, but the overall potential looks very limited.  Rain should move into Southern Michigan and eventually weaken in Ontario on Thursday, while isolated storms will move through Ohio during the afternoon. Rainfall amounts should range from 1/4" to 3/4" in Ohio, with less in extreme southern Ontario.  Less than a tenth of an inch (2-3mm) of rain is currently expected in the Greater Toronto Area.

Temperatures will generally range in the low to mid 70s (21-27C), but rain could keep local areas from warming up as much.