Snow still expected Tuesday night into Wednesday…

First off, it needs to be mentioned that there will be 1-3 inches of snow overnight tonight for most of southeast Michigan (except for Lenawee and Monroe counties can expect 2-4 inches).  The heaviest snow can be expected between about 1am-4am.

Now on to the major winter storm…there have been some slight changes in the models that could lower totals somewhat from what has been discussed over the weekend.  Either way this is still going to be a big winter storm with plenty of snow.  Let’s take a look at what to expect.

This storm is in the strengthening/organization period of its life at this current time.  Looking at the image below, you can see that there are two upper level waves, one to the north and another to the south.  These waves will phase with each other which will result in the strengthening of the southern wave.  This southern wave will then move into Texas and then shift to the northeast in our direction.  

 Image courtesy of NWS

With the upper level wave strengthening, the low pressure system at the surface will rapidly strengthen as well.  This surface low and its counterclockwise spin will cause the winds to blow northward over the Gulf of Mexico which will transport plenty of moisture northward into our direction.  The two images below show the expected position of the surface low pressure system Tuesday evening and Wednesday morning as it approaches Michigan.

 Images courtesy of HPC

So the strong system with plenty of moisture (along with other upper level dynamics) will give us a rather large winter storm.  The current winter storm watch is for 4pm Tuesday to 7pm Wednesday and the current forecast is for 8-12 inches to fall during this time.  The heaviest snow is forecasted to fall between 1am-7am Wednesday morning where 5-8 inches of the total could occur.  Yesterday I said 8-12 was conservative, and it still can be, but this morning’s models have suggested that the system will track further south than originally anticipated, and the dynamics involved could be weaker than once thought.  Either way, this will be a strong storm.

I will write another posting tomorrow during the afternoon after the morning weather models come out to give a final forecast for the snow totals. 

Winter storm watch 7pm Tuesday to 7pm Wednesday…

The National Weather Service has issued a winter storm watch for most of southeast Michigan in anticipation of the winter storm that is forecasted to move into our region on Tuesday.  Below is a statement provided by the NWS along with a map of the counties in Michigan affected by the watch:

“...A STRONG WINTER STORM WILL TRACK THROUGH THE OHIO VALLEY TUESDAY NIGHT

AND WEDNESDAY. THE PASSAGE OF THIS SYSTEM TO OUR SOUTH WILL SPREAD

SNOW...POTENTIALLY HEAVY...INTO PORTIONS OF SOUTHEAST MICHIGAN

TUESDAY EVENING THROUGH WEDNESDAY. THE BEST POTENTIAL TO SEE HEAVY

SNOWFALL WILL BE ALONG AND SOUTH OF THE I-69 CORRIDOR. PRELIMINARY

SNOW AMOUNTS LOOK TO RANGE BETWEEN 8 AND 12 INCHES...HOWEVER

HIGHER AMOUNTS WILL BE POSSIBLE. GUSTY WINDS MAY ALSO DEVELOP

TUESDAY NIGHT INTO WEDNESDAY...LEADING TO AREAS OF BLOWING SNOW

AND FURTHER REDUCING VISIBILITIES. CONFIDENCE WITH A LARGE HIGH-

IMPACT STORM DEVELOPING IS HIGH...HOWEVER ADJUSTMENTS TO THE EXACT

TRACK AND HIGHEST SNOW ACCUMULATIONS ARE STILL POSSIBLE. THOSE

RESIDING IN OR PLANNING TRAVEL TO THE AREA SHOULD MONITOR THE

FORECAST CLOSELY FOR UPDATES.”

 Image courtesy of NWS

The 8-12 inch range mentioned above is a bit conservative considering what the weather models are showing, but this storm is still a few days away and there are a couple important details that need to be figured out before issuing higher totals. 

For example, as I mentioned yesterday, the exact track of this system is still an uncertainty and it will make a rather significant difference on how much snow we would get or if it would mix with ice.  The map below shows this morning’s forecasted track of the storms center by five different weather models (CMC, ECMWF, GFS, MRF, and NAM).  At 7am on Tuesday morning, four of the five models expect the low to be positioned in eastern Texas (except the CMC is forecasted the low to be in southeast Oklahoma).  The system is then expected to move to the northeast in our direction during the day on Tuesday.  This northeast track is extremely crucial to what we will experience with regards to accumulation and precipitation type.  The average track appears to be through southern Indiana into central Ohio and then moving to the east.  This track would favor us getting snow...and lots of it.  If the track goes further north as the CMC (in green) and NAM (in red) suggest, then we could receive a mix precipitation of snow and ice.  This would reduce our snow totals but could be dangerous if we get a long period of ice.  At this time, the more northern track (especially the CMC track) doesn’t appear to be favored by the meteorologists, but most of this morning’s model runs did have the track shift slightly to north compared to previous model runs.  So this is something that needs to be monitored closely because while we’re forecasted to get snow, to our south is forecasted to get a significant amount of ice, and if the track ends up shifting far enough north, then we could be talking about a significant ice storm rather than snow.  I still expect us to get mostly snow, but wouldn’t be surprised if there are periods of mixed precipitation here and there.

 

So assuming the current forecast of all snow will occur, what type of total range can we expect? As I said, 8-12 inches could be a conservative amount, but it could be correct.  The HPC is currently forecasting much more as shown by the two images below.  The first image shows the forecasted precipitation total for Monday evening to Tuesday evening.  The map has us in the 0.10 to 0.25 range of precipitation.  The second image shows the forecasted precipitation total for Tuesday evening to Wednesday evening.  The map has us in the 0.75 to 1.00 range of precipitation.  With Tuesday’s low forecasted to be around 16°F and Wednesday’s high forecasted at 22°F, I will use a precipitation to snow ratio of 15:1 and 18:1 which would give us…

15:1 ratio

0.10 * 15 = 1.50     to            0.25 * 15 = 3.75    

0.75 * 15 = 11.25   to            1.00 * 15 = 15.00

Totals...1.50 + 11.25 = 12.75

            3.75 + 15.00 = 18.75

18:1 ratio

0.10 * 18 = 1.80     to            0.25 * 18 = 4.50

0.75 * 18 = 13.50   to            1.00 * 18 =18.00

Totals...1.80 + 13.50 = 15.30

            4.50 + 18.00 = 22.50

So using the 15:1 ratio, the HPC is forecasting 12.75 to 18.75 inches of snow and using the 18:1 ration, the forecast is 15.30 to 22.50 inches of snow!  If this were to occur, this would be a historic winter storm for our area.  I know that these totals sound very high, and they could be overdone, but if the track is right and the storm is as powerful as it’s being forecasted, then this is possible.

 Both images courtesy of HPC

I will write another posting tomorrow to update on any potential changes and what we can expect.  This storm should be taken seriously because it will be powerful and no matter if we get snow or ice, we will get a lot of it.