Author: Chris Dzombak

Details are murky at this point, but Michigan will probably see strong wind, rain/freezing rain and snow between Monday night and Wednesday, and into Christmas Day.

Starting Monday night, a weak storm system is expected to develop over the northern plains and be absorbed by a stronger system moving up from the south.

The timing, location, track and intensity of this storm are difficult to estimate accurately at this time, but the Great Lakes region can expect to see the strongest part of the storm. Earlier in the storm — Monday night or Tuesday — we’re likely to see heavy, cold rain, and on Wednesday into Christmas Day we can expect some snow accumulation. Gusting wind will make it difficult to keep roads clear and blowing snow will affect visibility for drivers on Tuesday and Wednesday.

If you’re planning to travel next week, keep an eye on weather forecasts. Plan to travel on Monday, before the storm is predicted to hit southeastern Michigan.

ArborWX will track this as it develops; follow @ArborWX on Twitter for more frequent updates than are posted on the blog.

The outlook received from the Washtenaw County EOC follows.

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
VIA WASHTENAW COUNTY EMERGENCY OPERATIONS CENTER
251 PM EST FRI DEC 19 2014
 
A POWERFUL WINTER STORM IS EXPECTED TO DEVELOP ACROSS THE 
EASTERN UNITED STATES ON TUESDAY AND WEDNESDAY. ITS IMPACTS 
INCLUDING HOLIDAY TRAVEL...WILL BE FELT IN THE GREAT LAKES 
REGION FROM TUESDAY INTO CHRISTMAS DAY. THERE IS 
CONSIDERABLE UNCERTAINTY IN THE EXACT TRACK AND EVENTUAL 
STRENGTH OF THIS STORM. THESE UNCERTAINTIES COULD HAVE A 
DRAMATIC AFFECT ON THE CHARACTER OF THE WEATHER FOR 
SOUTHEAST MICHIGAN FROM TUESDAY TO CHRISTMAS DAY.
 
AT THIS TIME...THE STORM IS EXPECTED TO BE STRONGEST OVER 
THE GREAT LAKES REGION. THE MOST LIKELY WEATHER HAZARD FOR 
SOUTHEAST MICHIGAN FROM THIS POWERFUL STORM IS THE POTENTIAL 
TO PRODUCE SIGNIFICANT WIND GUSTS FROM TUESDAY NIGHT INTO 
CHRISTMAS MORNING. SOUTHEAST MICHIGAN HAS THE POTENTIAL TO 
SEE LOCALLY HEAVY RAINFALL ON THE WARMER SIDE OF THE STORM 
FROM TUESDAY INTO WEDNESDAY...BUT ALSO HAS THE POTENTIAL 
FOR SOME SNOW ACCUMULATIONS ON THE COLDER SIDE OF THE STORM 
FROM LATE WEDNESDAY INTO CHRISTMAS MORNING.

The NWS has published this outlook for winter in SE Michigan. It’s fairly technical, but they’ve conveniently summarized the important bits for us: December should be roughly normal, and January and February will probably be somewhat colder than normal, though not as bad as last winter.

It’s particularly humid today, and an area of low pressure is moving our way. The upshot of this is that you should expect rain on and off this afternoon into tonight, which might be heavy at times.

Severe weather isn’t expected, but localized thunderstorms might develop. Weather will mostly be moving from south to north.

More

Washtenaw County’s emergency warning sirens are tested at noon on the first Saturday of every month from March through September. So when you hear them tomorrow at noon, don’t worry.

If there is a threat of severe weather tomorrow, the test will be cancelled.

Sirens will be activated for the following emergencies:

• The National Weather Service has issued a tornado warning
• A severe thunderstorm has been detected with damaging winds in excess of 70 MPH
• A hazardous materials accident requires immediate protective action by the public
• An attack on the United States is imminent, underway or has recently occurred

Warning siren activation (outside of a test) is a signal to immediately go indoors and monitor local Emergency Alert System media outlets for official information.

Additional siren information