Update 2/27/13 - Feb 26-27, 2013 Snow Totals

Snowstorm Totals From the NWS DTX

Feb 26-27, 2013 Snow Totals

A strong low pressure system originating near Texas tracked northeast into the Ohio Valley. This storm induced blizzard, winter storm, and tornado headlines as it tracked through the US. As the low lifted north, a mix of rain, freezing rain, sleet, and snow commenced Tuesday afternoon. A changeover to snow began near 4-7pm for most areas. A general 3-5" swath of snow fell across most of Southeast Michigan. Text and graphic summaries are available below. Snowfall totals through 10 am February 27th, 2013, are available in graphic and text formats.

1016 AM EST WED FEB 27 2013


                          (INCHES)      (HOURS)        LAT       LON

   AUBURN                  M   2.6           12     43.60N    84.08W

   BURTON                  M   2.2           14     43.00N    83.62W
   FLINT                   M   2.8           14     43.02N    83.69W
   LINDEN                  M   3.0           14     42.82N    83.78W

   FILION                  M   0.6           12     43.90N    83.00W
   BAD AXE                 M   3.2           11     43.80N    83.00W

   LAPEER                  M   4.2           14     43.05N    83.32W
   LUM                     M   5.1           15     43.10N    83.15W
   NORTH BRANCH            M   5.4           14     43.23N    83.19W

   ADRIAN                  M   3.0           12     41.90N    84.04W
   TIPTON                  M   6.0           14     42.02N    84.06W

   HOWELL                  M   2.0           13     42.61N    83.94W

   STERLING HEIGHTS        M   3.0           13     42.58N    83.03W
   MOUNT CLEMENS           M   5.5            8     42.60N    82.88W

   MONROE                  M   0.8            M     41.92N    83.39W
   DUNDEE                  M   3.7           14     41.96N    83.66W

   HOLLY                   M   2.8           14     42.80N    83.62W
   2 N NOVI                M   4.0           12     42.50N    83.49W
   BLOOMFIELD HILLS        M   4.0           14     42.58N    83.25W
   CLARKSTON               M   4.0           14     42.74N    83.42W
   SOUTHFIELD              M   4.0           12     42.48N    83.26W
   FARMINGTON HILLS        M   4.3           14     42.49N    83.38W
   WHITE LAKE              M   4.5           14     42.65N    83.50W

   5 S MERRILL             M   4.0           13     43.34N    84.34W
   FREELAND                M   4.5           13     43.52N    84.12W
   HEMLOCK                 M   6.5           14     43.42N    84.23W

   DECKERVILLE             M   5.0           12     43.53N    82.74W
   LEXINGTON               M   5.0           13     43.27N    82.53W
   SANDUSKY                M   5.0           13     43.42N    82.83W

   CORUNNA                 M   3.0           12     42.98N    84.12W
   OWOSSO                  M   3.7           14     43.00N    84.18W

   YALE                    M   4.5           13     43.13N    82.80W

   FAIRGROVE               M   2.0           12     43.52N    83.54W
   VASSAR                  M   2.6           14     43.37N    83.58W
   CARO                    M   3.0           12     43.49N    83.40W

   SALINE                  M   3.6           14     42.18N    83.78W
   MANCHESTER              M   4.0           14     42.15N    84.04W
   5 SE ANN ARBOR          M   5.0           13     42.22N    83.66W
   CHELSEA                 M   5.0           14     42.31N    84.02W
   1 W ANN ARBOR           M   5.5           14     42.28N    83.75W
   DEXTER                  M   6.8           14     42.33N    83.88W
   1 S ANN ARBOR           M   7.0           14     42.26N    83.73W

   GROSSE POINTE FARMS     M   2.4           14     42.40N    82.89W
   ROMULUS                 M   3.0           14     42.22N    83.37W



Update 2/26/13...100 PM

Mixed precipitation will advance across Southeast Lower Michigan during the afternoon quicker than initially anticipated...therefore a longer period of rain...snow...sleet and freezing rain will occur into at least early evening. Because of more mixed precipitation; snowfall amounts will be impacted, especially over extreme Southeast Lower Michigan. Latest guidance /12z - 7AM/ continues to wrap in pockets of milder (above freezing air) into the storm into the evening anyway. This was the risk noted in earlier forecasts below and thus, snowfalls have been adjusted lower.

Snowfalls across extreme Southeast Lower Michigan from I-94 south to the Ohio border will be impacted the most with generally 1" - 3" likely. The remaining area of Southeast Lower Michigan;  Detroit, Detroit's northwest-northeast suburbs, Ann Arbor, Flint, Saginaw Valley and Port Huron amounts will vary from 2" - 3" over the extreme southern regions to 3" - 5" across the majority of the region into the northern areas. Best snowfalls will remain over the northeast counties including the Thumb where 4" - 6" is expected to accumulate. Stiff northeast winds will gradually shift to north at 15 to 25 mph with gusts around 30 mph into tonight before diminishing.

Update 2/25/13...

Generally I look for a 4" - 7" total of heavy wet snow over much of region from this system through  Wednesday - with much of that snow falling late Tuesday into midday Wednesday. Eastern counties, especially downwind of Lake Huron may see highest with isolated 8" or so possible.  I will update if the system information changes going into the event.

Overall very little has changed on our expected winter storm the past few days as most models continue to prog the storm in the track first outlined in the original blog 2/23. In fact; the major models are in remarkable agreement as to the general track of the low center with a subtle shift southward of both the 500H MB and surface low in the last 12-24 runs.

The European continues this lead (I originally chose in the initial blog below) with now both the GFS and the European pretty well in step. Of course; the devil is in the details...and in this case the problems lie in precipitation amounts and how much "warm air" gets entrained into the lower levels of the atmosphere. While this system somewhat resembles our Dec 26th storm it is much further north and thus; milder but at the same time the dynamics of the system are more impressive overhead as is its moisture feed from initially the Gulf and subsequently Atlantic.

The system has well developed features aloft including; a compact negative tilt structure that consolidates into a "bowling ball" shape that "hooks" for the Ohio pocket as she heads northeast. Meanwhile; the surface system along with the 700MB low follow along in good measure right into Southeast Lower Michigan and Northwest Ohio. And old rule of thumb with the 700 MB; to the left of center, generally the best snow can be expected in a mature system. And, while our storm is projected to weaken with time as she treks toward the Eastern Lakes; she still maintains a moderately impressive storm structure in our neck of the woods from Tuesday evening into the first half of Wednesday. In addition; right about the same time Atlantic moisture should rev-up into the system in conveyer-belt like fashion later in the aforementioned period. Good vertical velocity and energy aloft should make for a good dump of precipitation later Tuesday into Wednesday morning...though as with most systems this season, heaviest precipitation will be south and east of us...a noted trend this winter. Snowfall rates in spite of temperatures initially falling just into lower to mid 30s after precipitation onset may approach an inch an hour in the late afternoon to evening time frame in heavy wet snow. This timing may change if the precipitation advance slows a bit. A mixed bag of precipitation is also still in the cards, especially over extreme Southeast Lower Michigan and mainly in the initial stages of the event.
(see explanation below). A stiff and gusty northeast wind at 15 to 25 mph with gusts to around 30 mph will accompany the precipitation  into early Wednesday.

                                                500H with vorticity est maxima's (X)

Now; the above scenario is all nice and good but she (500 MB Jet) also gets the boot from energy diving into her back/west side which why may help with troughing westward; will also help move things along to the east. Therefore; the center of the best action doesn't stick around quite as long as I would like to see for the BIG accumulations.

Besides less precipitation than earlier expected; another problem is the system still nicks Southeast Lower Michigan enough so that pockets or envelops of "milder, above freezing" ice-crystal melting air will also mess with our snowstorm (it always seems these things are never easy around here). This continues to bring the risk of mixed rain, snow and sleet mainly at the onset. While this churning of milder air is seen in pockets aloft and at the surface early in the event, this should ultimately be offset by dynamic cooling aloft especially when considering precipitation intensity - along with the drier, cooler air feeding the system from the northeast. However; being so marginal aloft in the temperature departure lets the door open for the risk of some mixed precipitation well into early Wednesday.

Need a refresher on what determines snow, sleet or freezing rain? Or not sure what each type is?
Check out a great tutorial @ http://www.nssl.noaa.gov/education/svrwx101/winter/types/

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian


Original Blog 2/23...

As mentioned in my last blog, our models were intimating another storm for this coming week and snow lovers should not give up hope. Latest forecasts of all the models continue those earlier projections of bringing a large storm and low pressure area toward the Great Lakes this upcoming Tuesday into Wednesday...with lingering affects possibly lasting into Friday.

Meteorological data for this storm is now (Sat AM 2/23) being sampled over the far Western states and thus; the model runs are starting to get a better idea of the atmosphere projected to develop this storm. All data thus far; promotes the development of a Texas Hooker type of low pressure system Sunday  into Monday that slides into the Boot-heel of Missouri by Tuesday morning. The center of the storm is then expected to slide northeast across the western Ohio Valley through Tuesday night and be over Southeast Lower Michigan by Wednesday morning. This system appears to have the capability of bringing both Gulf of Mexico and Atlantic moisture to Southeast Lower Michigan.

While preliminary data supports a more significant storm than this past Friday's weakening storm, questions still arise as to the nature of the precipitation. At this time; the best estimates from the early data points to a mixed rain and snow scenario to arrive Tuesday afternoon before changing to all snow sometime Tuesday evening lasting into Wednesday. Heavy amounts of snow are possible with this system especially if the majority of the precipitation received is, in fact snow. Since this time period is still 3 - 4 days out and as you know in this business; things can change - but look for updates on the progress of the system into Tuesday.

Making weather fun while we all learn,
Bill Deedler -SEMI_WeatherHistorian

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