When Big and Little Combine… (Feb 7-8, 2013 Snowstorm)

A progressing shortwave, similar to our recent clipper systems, will cut down from Canada Wednesday and merge/phase with a longwave trough moving across the continental U.S. This interaction will ensure moisture transport from the deep south into the Great Lakes region, amplifying precipitation amounts in the area. In this way, it is different than our previous shots of snow.

This is a good example of how tricky weather can be. This past weekend, the storm was little more than a trace-3″ disturbance, now it threatens to bring triple that amount to some locations of the state. Quite interesting to see models not show agreement, and then all of a sudden snap in line with each other. Euro had this solution previously, and the GFS/NAM had come into agreement by Tuesday morning. This actually falls near a date back in 2008 when much of mid-Michigan had a 1-2 punch of snowfall:

On February 6, 2008, a snowstorm hit most of Southeast Michigan. Widespread amounts ranged from 6 inches across central Livingston, Oakland and Macomb Counties to greater than 10 inches for all of the Flint (11.3 inches at Bishop Airport), Tri Cities (12.0 inches at Tri Cities Airport)and Thumb regions. Areas across the southern Saginaw River Valley were dumped with 16 to 18 inches of snow from southwest Saginaw to Birch Run to Vassar. -Detroit/Pontiac National Weather Service

Accumulation wise, central Michigan and lower Michigan look to be in the cross-hairs for persistent snow beginning Thursday morning and continuing through to Friday morning. There is some discrepancy between the GRR(Grand Rapids) and DTX(Detroit/Pontiac) forecast offices. as to what the heaviest snow amounts will be. My experience is that GRR likes to over estimate snow accumulations, and DTX likes to hold a conservative line on accumulations. Typically with winter storms, you get little pockets of the high accumulations, but they are not as widespread as the forecast covers. These higher amounts will also depend greatly on how consistent the early snowfall is. Therefore, I believe isolated areas across mid-Michigan will receive 9″ or 10″, but most locations across mid-Michigan will see 6-8″. Along the I-94 corridor, a good swath of 3-6″ seems like a good bet as they will get high intensity snowfall, but for a shorter duration. With warmer temperatures moving into the region, this snow will have a wetter characteristic compared to lighter dry snows this past week.

Grand Rapids NWS depiction for snow accumulations through Friday morning.dtx

Snow will begin to trickle in Thursday morning for central Michigan. Snow should then continue through the day, intensifying in the afternoon. Overnight, snow will be at the strongest. This leaves little time for morning commuters to have  a clear surface, and roads will likely be covered and treacherous  Further south in the state, the initial snow will not begin until the afternoon/evening on Thursday, thus lower amounts are expected. However, once the main portion of the system is over the region, heavy snows will be occurring  and accumulation rates will be high enough to cause transportation issues.

The Detroit forecast office has a great briefing of timing, expectations, and other facts about the storm available to view in a PDF document online here.

Advertisements

Bitterly Cold Air Inbound

The cold will get colder next week as jet stream features carry cool air down from Western Canada (Alberta and Saskatchewan). Here is a rough ground estimated temperature from the GFS for Tuesday night. The red/blue lines show their listed temperature value, while the black lines show Mean Sea Level Pressure (MSLP) in millibars.

Cold air plume invading the Midwest from Canada.

Cold air plume invading the Midwest from Canada.

Thankfully, the warm nature of the Great Lakes will shield us Michiganders from the bulk of cold air. Notice how tightly the lines of temperature are packed north of Michigan indicating the strong temperature gradient. Also, directly west of Lake Michigan lies a -5F degree line, where we will stay a good 10 degrees warmer than that with lake shielding. Nonetheless, highs on Tuesday may only reach the mid teens, and the rest of the week struggles to get above 20. Nightly lows will be in the single digits, early morning commuters will be able to count the temperature with their fingers. These bitter temperatures combined with strong winds will make wind chills in the negatives, so bundle up!

As is common with cold air over a warm body of water, the lake effect snow machine will be churning. With this strong cold air mass moving through, shoreline locations will see a good bit of snow. Along the eastern shores of Lake Michigan accumulations will be as much as 6″. Lake effect snow events can vary in short-term, so will keep an eye on where accumulations will trend. (Worthwhile to note Grand Rapids NWS has a Winter Storm Watch out for counties along the Lake Michigan coast. Gaylord NWS also has Watches out for a little clipper coming across this weekend and the additional lake effect snows)

Dexter Township Emergency Sirens

About a week ago, I noticed a few new additions to the side of Dexter Township roads. Sirens. Thought nothing of it while driving pass, then I spotted another, and another. Turns out it didn’t take long for preparations to get under way after an EF-3 Tornado went through part of Dexter, MI this past spring.

Whelen WPS-2910 located at North Territorial and Lombardy Dr (#5 on map)

Went out to take a look at a Whelen WPS-2910 at North Territorial and Lombardy Dr (#5 on map)

The siren placement is pretty extensive and should offer a great coverage for the many residential communities in the area. The proclaimed 70dB level will hover just above normal conversation volume, enough to get your attention and administer action.

Dexter Township insert of siren locations.

Dexter Township insert of siren locations.

sirens2

The site at http://www.twp-dexter.org has been updating on the progress of the siren installation. As of December 13th, “The warning sirens are starting to go up throughout Dexter Township and testing may begin soon.”

If you haven’t searched for tornado sirens on YouTube, you are missing out on a very interesting group of people who love tracking these noise-makers down, filming their weekly/monthly tests. I enjoy a good eerie tone of siren tests now and then, but you must have a good ear to tell them apart! I found a sample of what they should sound like:

Snow n’ Cold

After a slow start to the snow season, a healthy coverage of snow has fallen. A few initial inches of snow fell for most of southern and central Michigan after a large storm moved through the Midwest on Dec 21. The winners during that storm were southern Wisconsin and Northern Michigan which picked up well over a foot of snow in parts.

Ground snow captured on visible satellite after the Midwest storm on Dec 20-21, 2012.

A day after Christmas, we received what was a glancing blow from a storm forming in the deep south and tracking up the Appalachian Mountains. These types of storms often look favorable to dump a significant amount of snow for Michigan. However, we often suffer a robbery of moisture. If conditions are favorable, the storm will redevelop off the east coast, thus displacing storm energy a few hundred miles east. This is a scenario that happens a lot, and computer models often overlook this in long-range forecasts.

Christmas storm radar imagery.

Compared to past instances if this storm type, I think SE Michigan faired well on the snow part. The deepest amounts showed up outside the  thumb as lake effect snows helped enhance snow totals. This snowfall also happened the night of Central’s bowl game at Ford Field in Detroit. That was an adventure on the roads! (CMU won, so that was icing on the cake!)

Total snow accumulations for SE Michigan.

This storm also brought storms producing tornadoes in the south on Christmas day. Luckily, no fatalities occurred, but plenty of people were injured in what could be the costliest Christmas day tornado outbreak.

The near future looks calm but cold. Overnight temperatures will start in the teens this week, but dip into the single digits by Wednesday and Thursday. Daytime highs will be in the teens. Many storm disturbances will pass well south of Michigan. These will roughly follow the jet stream as they develop in the south and exit the east coast a few days later. As these storms develop and move out to sea, it will help shift cooler temperatures south, and thus we get into stronger polar air. Bundle up, winter is here!