Mild, moisture laden air will surge north ahead of the storm center as colder, Polar air drives south; winding her up over the western Great Lakes later on Thursday. Latest computer models have converged somewhat on a fairly common track for early in the winter season; trekking from the Panhandle of Texas /Wednesday morning/, northeast through Missouri /Thursday sunrise/ and into the western Great Lakes (Southwest Lower Michigan) by Thursday evening. This panhandle low or Texas Hooker will affect much of the central, northern and eastern part of the country in some sort of way (see Short Range Discussion at the bottom of post).
Specifically closer to home across Southeast Lower Michigan; again this will be mainly a rain event as true Polar air (cold enough for snow) will be mainly absent for the balance of the precipitation event with this storm. With that being said; at the onset of the precipitation event from overnight Wednesday into Thursday morning, mixed precipitation is possible, especially over the northern half of Southeast Lower Michigan. Snow, or mixed rain and snow will changeover to rain during the overnight hours. For the balance of Thursday as the low approaches, wind blown rain and showers will circulate through the region before changing over to snow and snow showers late Thursday into Thursday night with the passage of the storm center. Sharply colder temperatures will accompany the strong gusty Northwest winds as temperatures fall from the 40s on Thursday, through the 30s Thursday night and into the mid 20s to around 30 by Friday morning.
Travelers be advised that roads could become slippery in places as the colder air and light snow amounts overspread the region Thursday night. Generally snowfall amounts on the backside of the low should fall into the inch to two inch category over Southeast Lower Michigan with heavier and much higher snow amounts further west and northwest over West and Central and Northern Michigan into the U.P. where Winter Storm Watches are flying.
Some Models are intimating another storm will develop on this newly formed fast track storm path around the Christmas holiday into the 26th. This is still highly speculative this far out but being its a heavily traveled week it is worth noting thay this would not be unreasonable given the dynamics and newly formed pattern and jet stream projected by some models into next week. So; stay tuned for confirmation.
For more on the expected weather and areas to be affected by this storm;
SHORT RANGE FORECAST DISCUSSION NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD 352 PM EST TUE DEC 18 2012 VALID 00Z WED DEC 19 2012 - 00Z FRI DEC 21 2012 ...ACCUMULATING SNOWS ARE EXPECTED FROM THE CENTRAL ROCKIES UP INTO THE UPPER GREAT LAKES... ...EPISODES OF SEVERE WEATHER WILL BE POSSIBLE FROM THE LOWER MISSISSIPPI VALLEY EASTWARD TOWARD THE SOUTHEASTERN U.S... ...HEAVY SNOW WILL CONTINUE TO IMPACT THE MOUNTAINS OF THE NORTHWESTERN CONUS... ...UP TO AN ADDITIONAL FOOT OF SNOW WILL BE POSSIBLE OVER AREAS OF NORTHERN NEW ENGLAND... A DYNAMIC UPPER TROUGH CURRENTLY SLIDING SOUTHEASTWARD THROUGH SOUTHERN/CENTRAL CALIFORNIA WILL QUICKLY REACH THE FOUR CORNERS REGION BY EARLY WEDNESDAY. DURING THESE NEXT 24 HOURS...STRONG VERTICAL LIFT WITHIN THE UNSTABLE AIR MASS WILL WORK IN ACCORDANCE WITH UPSLOPE FLOW TO PRODUCE MODERATE TO HEAVY SNOWFALL ACROSS THE SOUTHWESTERN U.S. THE HEAVIEST AMOUNTS ARE EXPECTED ACROSS WESTERN COLORADO WITH OVER A FOOT POSSIBLE IN CERTAIN LOCATIONS. ONCE THIS SYSTEM REACHES THE LEE OF THE ROCKIES BY MIDDAY WEDNESDAY...INCREASING LOW-LEVEL MOISTURE FROM THE GULF WILL BEGIN TO OVERRIDE THE WEST-TO-EAST ORIENTED WARM FRONT. MUCH OF THIS OVERRUNNING PRECIPITATION SHOULD FALL AS SNOW ACROSS THE CENTRAL PLAINS AND MIDDLE MISSISSIPPI VALLEY. THE TIGHTENING PRESSURE GRADIENT WITH THE INTENSIFYING CYCLONE MAY LEAD TO PERIODS OF BLIZZARD CONDITIONS OVER SECTIONS OF EASTERN COLORADO/WESTERN KANSAS PER THE LATEST FORECAST OFFICE WATCHES/WARNINGS ISSUANCES. WHILE UP TO A HALF A FOOT OF SNOW IS EXPECTED ACROSS THE CENTRAL PLAINS...MORE ENHANCED AMOUNTS EXCEEDING A FOOT WILL BE POSSIBLE FROM SOUTHERN WISCONSIN UP INTO CENTRAL MICHIGAN. THIS IS IN RESPONSE TO A DEVELOPING COMMA-HEAD OF SNOW ON THE BACK-SIDE OF THE SURFACE LOW AS IT DEEPENS ACROSS THE UPPER GREAT LAKES. BESIDES THE WINTRY PRECIPITATION EXPECTED...SEVERE WEATHER WILL BE POSSIBLE FROM THE LOWER MISSISSIPPI VALLEY OFF TOWARD THE SOUTHEASTERN U.S. FROM WEDNESDAY INTO THURSDAY. THE COMBINATION OF A DEEP AND EXPANSIVE UPPER CYCLONE SETTING UP OVER THE NORTHEASTERN PACIFIC WITH CONTINUAL ONSHORE FLOW WILL SET THE STAGES FOR RATHER HEAVY SNOWFALL ALONG THE NORTHWESTERN U.S. MOUNTAIN RANGES. THE AIR MASS IN PLACE REMAINS COLD ENOUGH TO SUPPORT SNOW OVER THE MUCH OF THE REGION AND EXTENDING EVEN NEAR THE COASTLINE OF NORTHERN CALIFORNIA WHERE WINTER STORM WATCHES ARE IN EFFECT. MOISTURE TRANSPORT SHOULD BE ON THE INCREASE ON WEDNESDAY AS THE UPPER LOW DROPS DOWN FROM THE GULF OF ALASKA WHICH WILL MARK THE BEGINNING OF THE HEAVIER SNOWFALL. THE LATEST HPC WINTER WEATHER FORECAST SUGGEST 2 TO 3 FEET WILL BE POSSIBLE THROUGH THURSDAY EVENING ACROSS THE SHASTA...WASHINGTON/OREGON CASCADES...ALONG WITH THE OLYMPICS. THE ACTIVE WEATHER PATTERN WILL ALSO IMPACT SECTIONS OF THE NORTHEASTERN U.S. AS AN UPPER TROUGH STRENGTHENS ALONG COASTAL NEW ENGLAND. A MIX OF PRECIPITATION TYPES WILL BE POSSIBLE BUT SNOW SHOULD PREVAIL OVER MUCH OF NORTHERN/CENTRAL MAINE. 6 TO 12 INCHES OF SNOW IS EXPECTED OVER THIS REGION IN ADDITION TO ANY ACCUMULATIONS THUS FAR TODAY.
Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian
Original Post 12/16-
All our guidance models are converging on a similar solution for a strong storm to affect the Great Lakes region later this week. Latest indications for Southeast Lower Michigan is that the storm will bring rain, wind and milder weather ahead of the system late Wednesday into early Thursday. Colder temperatures will flood the region early Thursday on strong gusty northwest winds and any residual moisture will change over to snow and snow showers. Note; a track further south, as depicted in the Euro could bring more of a mix of precipitation with colder temperatures late Wednesday into Thursday morning.
The system is still days away and better sampling of dynamics that will create the storm are too. Needless to say, further updates on this early winter storm, its track and resulting weather will be forth coming. Below are the two locations from model projections for this intense storm from Sunday morning's guidance for Thursday morning. Stay Tuned.
|Making weather fun while we all learn,|
Bill Deedler -SEMI_WeatherHistorian