Winter 2004-2005 Outlook

Wild, Wide-Ranging, Wacky Winters

Written by: William R. Deedler, Weather Historian
National Weather Service Detroit/Pontiac, MI
October 27th, 2004

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OVERVIEW

While national climate guidance indicates equal chances (EC) for above normal and below normal temperatures, researched local guidance is used to help spot any potential trend that might be helpful. For reasons elaborated on in the following research, the consensus is to go with our strongest indicators of near normal to below normal temperatures for the upcoming Winter of 2004-05. The two-tier temperature outlook is used because of the likelihood of wide variances (a.k.a. roller-coaster pattern) during the winter months as suggested strongly by the 15 selected winters and recent trends.

Even more challenging than the temperature patterns, season snowfall amounts in the research varied greatly. In this year's researched winters, based on a weak El Niño, seasonal snowfalls range from as low the teens (in inches) to as high as the 70s and 80s (and frequently making the top ten lists whether it be top ten snowiest or snowless winters)! Here, our research and recent trends suggests a winter similar to last few winters with snowfalls actually ranging from below normal to above normal...depending largely on location and storm track. The key here is when and where the dominant storm track sets up. At this time, a slight edge is given to a more southern storm track (similar track to that seen in the Winter of 2002-03). Therefore, while near normal will be the general (or average) category used for this winter's expected snowfall, snowfall totals are still expected to range from below normal to above normal.

PAST RELEVENT TO THE FUTURE?

The overall Pacific water temperatures have basically oscillated around neutral to weak El Niño conditions for the past few years. The local research of the past several seasons for Southeast Lower Michigan under this pattern has strongly suggested a more dominant roller-coaster temperature pattern and intermittent feast or famine precipitation scenarios. Anyone living in Southeast Lower Michigan the past couple of years can surely attest to that given the existence of more extreme or unusual weather patterns, in a state that is known for it. To get a good feel for the upcoming winter, all one has to do is pause and briefly reflect on the past few years.

After having one of the hottest summers in recent memory in 2002 (and scoring high on the top ten hottest Summers list across Southeast Lower Michigan), the Winter of 2002-03 also landed in the top 20 lists, but this time it was for the record cold and/or snow at all locations. After, the Summer of 2003 did an about-face to the Summer of 2002 with generally, below normal temperatures and making the record books by way of numerous thunderstorms and severe weather.

Map of average temperature across the United States, Summer 2004; Click on image to enlarge Last winter's (2003-04) pattern showed itself by way of "near normal temperatures" during a winter that, ironically was anything but normal. There were frequent monthly, weekly and sometimes, even daily temperature swings ranging from much above normal to much below and back again. Like the previous winter /2002-03/, total snowfall this past winter season ranged widely from two feet /24.1"/ at Detroit Metro Airport, to over four feet at both Flint and Saginaw, to higher than five feet /62.6"/ here at the NWS in White Lake. Last winter's weather was offset nicely by a very mild spring but contained excessively dry conditions in April and record breaking wet conditions in May. Nearly a century had passed since an April had been as dry as April 2004 /.69"/ in Detroit, placing it fourth for driest Aprils on record and Flint, with just .70", had its second driest April ever recorded. The tables turned abruptly again in May to excessively wet conditions. All stations (DTW/FNT/MBS/DTX) reported over eight inches of rain, which gave the region record or near record rainfall totals for May (and second wettest month ever at Detroit) which resulted in record flooding at some locations. The Summer of 2004 contained some interesting weather patterns and trends of its own with nearly persistent unseasonably cool weather (landing in the record books here and across the country). Last summer also contained storm numbers and severe weather statistics superseding that of the records just set the summer (2003) before!

We are now about half way into the autumn season and the temperature and precipitation roller-coaster shows no abatement with Southeast Lower Michigan recording one if its warmest and driest Septembers on record. Like this past spring, a flip-flop in the upper air pattern, from trough to a ridge over the area, led to the "summer in September" weather. The warmth this past September many times rivaled that of the recent so-called summer months of June and more surprisingly, August! While the number of below normal temperature days overwhelmed the number of above normal days all summer, the reverse took hold in September. Shortly after, the expected strong shift in the jet stream (see Autumn 2004 Outlook) brought much colder air with record or near record lows within the first few days of October. Just recently, more temperature swings in October led to additional frosts/freezes and then, a dash of delightful Indian Summer weather popped in during the closing week of the month (a trend reminiscent of last October).

El Niño index; click on image to enlarge The above climate pattern of the past few years has evolved as Pacific Sea Surface Temperatures (SST) floated around normal (Neutral State) to a degree or so above normal (Weak-Moderate El Niños). It has been stated in the Local Outlooks/Reviews of the past few years that the local weather pattern has in some ways, resembled that of the mid 70s to the early 80s. Note the Pacific SST pattern during that time and lately, from around 2000 through the current time. In addition, the solar cycle of the mid 70s matches well to the current cycle with the lull coming in about 1977 (as compared to the current one expected about 2006).

WINTER TEMPERATURES:

While national climate guidance indicates equal chances (EC) for above normal and below normal temperatures, researched local guidance is used to help spot any potential trend that might be helpful. Temperature variability, sometimes rather extreme, is strongly suggested not only by this year's research but also by recent trends. Temperature data reflected in the selected researched winters (Fig-1) have an incredible range, including everything from the top ten coldest to warmest winters!

That being said, for reasons elaborated on in the following research, the consensus is to go with our strongest indicators of near normal to below normal temperatures for the upcoming Winter of 2004-05. The two-tier temperature outlook is used because of the likelihood of wide variances (a.k.a. roller-coaster pattern) during the winter months as suggested strongly by the 15 selected winters and recent trends. While some wide temperature swings are expected, in the final analysis, near normal to below normal temperature averages are likely.

WINTER SNOWFALL:

Even more challenging than the temperature patterns, season snowfall amounts in the research varied greatly. This was also seen with last winter's research and local results (with snowfalls ranging from much below normal to well above). In this year's researched winters, seasonal snowfalls range from as low the teens (in inches) to as high as the 70s and 80s (and frequently making the top ten lists whether it be top ten snowiest or snowless winters)! Here, our research and recent trends suggests a winter similar to last few winters with snowfalls actually ranging from below normal to above normal...depending largely on location and storm track. The key here is when and where the dominant storm track sets up. At this time, a slight edge is given to a more southern storm track (similar track to that seen in the Winter of 2002-03).

Therefore, while near normal will be the general (or average) category used for this winter's expected snowfall, snowfall totals are still expected to range from below normal to above normal. If the expected storm track materializes, snowfall should range from near normal to above from the northern suburbs of Detroit south to the Ohio Border, while normal to below is expected further north up across the Saginaw Valley into the Thumb Region.

PRESENT AND POTENTIAL HEMISPHERIC CONDITIONS

The Climate Prediction Center's outlook for El Niño this upcoming Winter of 2004-05 states that weak El Niño conditions are likely to continue through the Winter of 2004-05. Although there is still some uncertainty in the forecasts about the timing and intensity of El Niño, the consensus of climate models indicate that the El Niño will be on par, or weaker, than the most recent El Niño during the Winter of 2002-03.

As important, if not more, than the progress of El Niño will be the evolution of the North Atlantic Oscillation (NAO) and the Eastern Pacific Oscillation (EPO). These two climatic patterns have been discussed in these outlooks several times in the past but for review, the NAO basically is the dominant upper wind flow pattern over the North Atlantic influenced by the ocean. While in a negative phase, the NAO sometimes tends to act as a block (or dam) to the upper wind flow over the eastern half of North America. This blocking effect, in turn, tends to deliver the polar/arctic air into the eastern half of the country and Great Lakes more readily. The Arctic Oscillation (AO), which is a basically a subset of the NAO, is mainly responsible for surging polar and Arctic Air into the region when in a negative phase during the winter. The negative phase of these oscillations generally encourages low pressure troughing over the central and eastern areas of the country. It is when this pattern phases with the sub-tropical Jet Stream (further south over the US) that the southern storm track is energized and past substantial winter storminess has resulted for Southeast Lower Michigan.

The Eastern Pacific Oscillation (EPO) is the upper wind flow over the Eastern Pacific influenced by the ocean. When in a positive phase, the EPO generally is reflected by dominant stronger zonal flow and/or troughing along the West Coast of the U.S. This is in response to lower pressure over the Gulf of Alaska that extends south off the coast of Western Canada, while higher pressure dominates across the central Pacific. This combination, in turn, tends to funnel milder Pacific air well inland into the country and thus, limits Arctic outbreaks by holding them at bay up in Canada. When the EPO is dominated by a negative phase (as with the NAO), more ridging develops along the West Coast as higher pressure extends from the Gulf of Alaska south along the West Coast of Canada (opposite of the positive phase). This, in turn, encourages a northwesterly flow from Canada into the middle and eastern sections of the US and thus, the delivery of polar or arctic air. For more on the Pacific Decadal Oscillation. which includes the EPO, see: http://tao.atmos.washington.edu/pdo/

It has been observed in the past several winters, that it is when the NAO and EPO Oscillations align (both negative - colder, or positive - warmer) that out local weather pattern frequently takes the decided turn toward that colder or warmer scenario. This was the case during the winter of 2002-03 was pretty much dominated by a negative NAO and EPO and this was reflected well by overall persistent cold and storminess. The winter of 2003-04 temperature pattern was more mixed which resulted partially from a strongly negative NAO dominating most of January and first part of February, while a neutral to positive NAO held in December and again late winter. Along with the aforementioned factors, other considerations are taken into account for this winter outlook. The weather trends of the last year and how well they relate to the weather trends proceeding the 15 winters are researched in the study. In addition, a check of the solar activity during the years of the researched winters are checked. More information is available on possible climate affects of the solar cycle.

It is suspected that sunspot activity has an impact on climatic trends and patterns over the earth. The current sunspot cycle is compared with the sunspot cycles (timing/intensity) of past winters in the study. During the Winter of 2004-05, sunspot activity is expected to continue to wane with the sunspot cycle bottoming in the next few years. It is interesting to note the relationship between some of our more severe winters and the lull in the solar activity timing/intensity). As an added feature this year in the outlook, the solar cycle periods will be included in Fig-1 that were at or close to this winters by way of a /SCD/, while a /SCB/ is close to, but ahead of this winter (in other words, at the bottom of the cycle) and a /SCU/ means near the same level (or intensity) as this winter but in an uptrend. While, there have been studies done relating solar cycle lulls and colder winters, there clearly are several other factors involved here. Nearly all of the study winters played-out near the lull of the solar cycle and note the mild winters that also occurred at/or near that level (see Mild Winters below).

Other factors, such as the Great Lakes autumn water temperatures and soil conditions (moisture and temperature) also are taken into account (especially for early winter conditions).

The following winters were researched under a weak El Niño:

(Fig - 1)
15 WEAK EL Niño WINTERS RESEARCHED FOR THE 2004-05 WINTER
Average Temperature Season Snowfall
Detroit FlintSaginawDetroitFlintSaginaw

1971-2000 30
Year Normals-
27.1 23.9 24.0 44.0 48.3 44.5
100 Year
Average-
26.5 - - - - -

WinterSolar
Phase
Average Temperature Season Snowfall
Detroit FlintSaginawDetroitFlintSaginaw
1875-76 /SCB/ 31.0-14- - - 38.6 $ - -
1885-86 /SCD/ 28.2 - - 56.7(16) - -
1899-00 /SCD/ 26.1 24.2* - 69.1(4) - -
1911-12 /SCB/ 21.8(13) 19.7* 19.6 58.0(14) - 59.3(15)
1918-19 - 32.3-9- 27.3* 29.0 15.2-4- 29.9* 23.6-8-
1925-26 /SCU/ 26.1 24.5* 23.1 78.0(2) 64.9* 54.0
1931-32 /SCB/ 35.6-2- 33.4* 33.2-1- 26.2 28.4* 31.0-6-
1946-47 /SCD/ 28.0 25.9 24.4 30.0 48.7 54.4
1951-52 /SCD/ 29.0 26.5 25.0 58.6(13) 75.3(4) 83.5(2)
1963-64 /SCB/ 27.7 24.8 24.3 32.5 36.6 21.9-6-
1976-77 /SCD/ 19.8(3) 16.9(1) 18.3(8) 43.9 44.8 18.5
1977-78 /SCB/ 20.4(7) 19.1(5) 17.9(6) 61.7(8) 50.6(20) 55.6(20)
1986-87 /SCD/ 29.1 27.5 27.1 49.7 38.6 25.0
1994-95 /SCD/ 29.6 26.0 26.1 33.5 42.5 28.5
2002-03 - 24.1 22.5(17) 21.3(19) 60.9(9) 52.1(15) 42.4

Averages: 27.2 24.5 24.1 48.1 46.0** 41.5**

(  )Coldest or Snowiest Ranking
-  -Warmest or Snowless Ranking
$Incomplete (20" Jan 1876 and 18.6 Feb 1876, rest missing)
/SCD/Solar cycle phase in a downtrend and closest to that of the upcoming winter
/SCB/Solar Cycle phase close but ahead of this winter and AT the bottom of the phase
/SCU/Solar Cycle phase near same level as this winter but in an uptrend
*Not an Official Record and not in ranking (Official Records Began in 1942)
**Sample Incomplete and Therefore Not a reliable Snow Average

RECENT TRENDS AND COMPARISONS

Temperatures/Precipitation:

In researching the above winters, the trends during the proceeding year (since the winter of 2003-04) were noted and compared to the weather in the above winters and their proceeding year. Any occasional or frequent recurring weather correlations were noted between the years. This research was primarily based on the most complete database of records at Detroit.

Right out the gate, one of the most interesting items to surface was the number of cool summers that proceeded these selected weak El Niño winters. A substantial nine of 15 summers averaged below normal (like this past summer), four out of the remaining six averaged just near normal (summer of 2003 averaged norm - below) and finally, just two summers averaged above normal. In addition, the majority of the precipitation patterns of the previous winter through the summer and fall resembled the past year's of feast or famine with alternating dry and wet periods (monthly or seasonal). Therefore, as the saying goes, "we're in the right area" but what about the future and this winter?

As far as summer precipitation patterns, nine summers averaged dry (or below normal rainfall), five above normal and one normal. Temperature patterns are less tricky than precipitation patterns since chances are, if one place had below or above normal summer temperatures, so did much of the remaining area. Summer rainfall patterns, however, can be a different story especially when the "feast or famine" regime is already a part of that story. Take for example, this recent summer where Detroit and the northern suburbs had basically above normal rain, but Flint northward into the Saginaw Valley and Thumb Region received below normal rainfall. Since the precipitation variability is more notable in any summer season, little can be deduced from the summer rainfall pattern to help with the winter outlook. The only weak pattern that emerged was that all but one of the wet summers were followed by a snowy winter. One possible explanation could be, the winter storm track remained near the same area of the previous summer's and thus, above normal precipitation fell in both seasons.

Interesting, the basic trend seen this past summer and subsequently predicted earlier in our "Autumn Outlook" again shows up nicely in this latest research set of weak El Niño falls and winters. The majority of autumns started out fairly nice (again, not unlike this autumn, Autumn of 2003 and 2002) with above normal temperatures dominant in September and/or the first half of the autumn, along with below normal rainfall. Thereafter, the data becomes more mixed in October with about half the Octobers having above normal temperatures and half, below. And yet, the drier than normal trend seems to hold through much of October with more than half of them still having below normal rainfall. In the same token, more aggressive than usual early season cold blasts (some bringing initial frosts, freezes and possible snow) continue the trend seen the past few autumns. This pattern leads into a November, where the majority contain normal to below normal temperatures. As the "slide" toward below normal territory becomes more apparent, there is a stronger possibility of an early snow(s). As far as snow, note below the Novembers in the study that had measurable (and above normal) snowfalls at Detroit.

(Fig - 2)
NOVEMBER SNOWFALL TOTALS IN RESEARCHED WINTERS AT DETROIT
Normal Snowfall (1971-2000) in November: 2.7"
MONTH/YR SNOWFALL
Nov 1885 0.5"
NOV 1911 7.0" *
NOV 1925 7.8" * (2.0 in October)
NOV 1931 0.7"
NOV 1946 0.3"
NOV 1951 8.3" *
NOV 1976 1.4"
NOV 1977 7.4" *
NOV 1986 3.3" *
Nov 2002 1.4"
* Above Normal Snowfall
(Measurable snow in October)

WILD, WIDE-RANGING, WACKY WINTERS

This year's researched winters contain some of the most variable weather data seen to date in these Season Outlooks. Winter average temperatures for Detroit, alone, range from 35.6 degrees in the incredibly mild Winter of 1931-32 (second warmest winter on record) to the bitterly cold Winter of 1976-77 with 19.8 (third coldest on record), or a range of nearly 16 degrees /15.8/! And, it doesn't stop at temperatures either. Season snowfalls at Detroit range from a meager 15.2" (or fourth snowless season since 1880) to a whopping 78.0" (second snowiest season), or a range of nearly 63" /62.8/! While these ranges are extreme, they accurately reflect the potentials of the winter weather with the present pattern.

Strength of El Niño and phases of the EPO/NAO are seen as vital elements to this winter's outcome. There was also a fairly consistent correlation between the strength and extent of El Niño and the resultant weather. In other words, the stronger and more widespread the El Niño, the more likely it would be milder in Southeast Lower Michigan. Of particular concern, however, during weak to moderate El Niño phases is the extent the waters warm off the coast of South America, rather than just the central Pacific. Some of the weaker El Niño's (where the eastern Pacific did not warm appreciably) tended to energize the sub-tropical jet stream and at the same time, if the NAO remained in a negative phase, the risk of phasing the jets and resultant storminess may be higher. Questions arise about the interaction of the more active Pacific subtropical jet (due in part to El Niño) and the phases of the EPO and NAO previously mentioned.

Reviewing the earlier archives of the EPO and NAO trends available (since the winter of 1951-52), may shed at least some light on these variances. Just the mere fact that the majority of summers preceding the researched winters were cooler than normal, intimates the NAO/EPO phases most likely leaned toward the negative direction in the summer.

THE ROUGH WINTERS

In researching these weak El Niño (or Neutral winters) in the past, it was found that when conditions come together just right, these winters can be quite stormy and tempestuous.

Check out these rough winters in the research...

(Fig - 3)
WinterSolar
Phase
Average TemperatureSeason SnowfallSnowy
Months
DetroitFlintSaginawDetroitFlintSaginaw
1899-00 /SCD/ 26.1 24.2* - 69.1 (4) - - F/M
1911-12 /SCB/ 21.8(13) 19.7* 19.6 58.0(14) - 59.3(15)J/F/M
1925-26 /SCU/ 26.1 24.5* 23.1 78.0 (2) 64.9 54.0 J/F/M
1951-52 /SCD/ 29.0 26.5 25.0 58.6(13) 75.3 83.5(2) J/F
1976-77 /SCD/ 19.8(3) 16.9(1) 18.3(8) 43.9 44.8 18.5 J/M
1977-78 /SCB/ 20.4(7) 19.1(5) 17.9(6) 61.7(8) 50.6 55.6(20)D/J
2002-03 - 24.1 22.5(17) 21.3(19) 60.9(9) 52.1(15)42.4 D/J/F


(  )Coldest or Snowiest Ranking
-  -Warmest or Snowless Ranking
/SCD/Solar cycle phase in a downtrend and closest to that of the upcoming winter
/SCB/Solar Cycle phase close but ahead of this winter and AT the bottom of the phase
/SCU/Solar Cycle phase near same level as this winter but in an uptrend
*Not an Official Record and not in ranking (Official Records Began in 1942)

Since 1950, more data is available to do a better investigation on the rough or hard winters. The winters of 1951-52, 1977-78 and 2002-03 all contained well above normal snowfall with around normal to below normal temperatures (though in the Winter of 1951-52, Detroit averaged a rather mild 29 degrees). These three winters unfolded while a weak El Niño was in place. Since these winters were rougher winters, it was not surprising to find that a negative phase dominated both the EPO and NAO much of the winter. These negative phases of the EPO and NAO worked in conjunction to help deliver the polar and Arctic air into the Great Lakes region. This, in turn, more than offset any warming from El Niño. An important change came in October over the region (not unlike found in the research done for the Winter 2002-03 Outlook, and subsequently seen in October 2002, 2003 and just recently in October 2004 to a some extent). While these October's did contain some beautiful nice warm weather, the largely amplified pattern was also responsible for delivering some impressive record breaking cold and occasionally, even early snow. The Winter of 1976-77 was a bitter-cold winter that actually "began" in October and ranks at/near the top for coldest winters both Flint and Detroit. Snowfall that winter just climbed into the normal category also at both cities, whereas Saginaw remained pretty much north of the main storm track, receiving just 18.5" of snow.

SNOW-BOUND MONTHS

There was really no distinctive timing indicator as far as the snowiest month(s), as evidenced by the snowy winters data with the snowy time really occurring at any time of the winter (this is unlike what was seen in other Winter Outlook years). There are only a few weak trends seen here: 1) The earlier winters in the group tended to be back-end loaded with February/March Period being snowy. In the later winters, this subtle "trend" shifted back toward the early-mid winter period (December/January). Remember, however, a number of these snowy winters actually had an early start in November. 2) If one month was singled out to have the best chance to be snowy, it would be January. Looking at most winters, more often than not, there usually is a distinctive snowy period anyway and so, if the winter starts out snowy, chances are there will be a break and less snow will fall later (in mid or late winter) and visa-versa.

SOME OF THE BIG ONES

Of the winters where the data is available, negative phases of the EPO and NAO more often than not, prevailed during the winters of 1951-52, 1976-77, 1977-78 and recent winter of 2002-03. All winters displayed an active southern stream storm track (aided by El Niño). The Winter of 1951-52 was an exceptionally stormy winter with heavy amounts of snow across the entire Southeast Lower Michigan area along with an impressive "roller-coaster ride". The Winter of 1977-78 was also a busy, cold winter that contained the super-storm of January 26-28th, 1978 Blizzard, which brought the lowest pressure reading on record to a number of weather stations with its visit (including Detroit with 28.345"). In the 1978 storm, a strong phasing of the subtropical and Arctic jet under an evolving negative EPO and NAO, help set the stage for the creation of that monster. Another super-storm was bore out of these winters and that was during the Winter of 1885-86, but ironically, it was in the spring - April 6, 1886. That massive and unseasonable storm brought the most snowfall ever recorded at Detroit from one storm, 24.5"!

WINTER, WHAT WINTER? THE MILD WINTERS

With the wide range of winters under the 15 researched winters, perhaps it's not surprising just how mild some of the winter actually turned out to be.

(Fig - 4)
WinterSolar
Phase
Average Temperature Season Snowfall
DetroitFlintSaginawDetroitFlintSaginaw
1875-76/SCB/ 31.0-14-   -  - 38.6$   -   -
1918-19 - 32.3-9- 27.3* 29.0 15.2-4- 29.9* 23.6-8-
1931-32/SCB/ 35.6-2- 33.4* 33.2-1- 26.2 28.4* 31.0 
1963-64/SCB/ 27.7 24.8 24.3 32.5  36.6 21.9-6-


(  )Coldest or Snowiest Ranking
-  -Warmest or Snowless Ranking
$Incomplete (20" Jan 1876 and 18.6 Feb 1876, rest missing)
/SCB/Solar Cycle phase close but ahead of this winter and AT the bottom of the phase
*Not an Official Record and not in ranking (Official Records Began in 1942)

Looking at just Detroit, three out of the 15 winters were exceptionally mild, so mild that they made the top 20 mildest winters list. All of the four listed above, were not only relatively mild, they contained light amounts of snow. The Winters of 1918-19 and 1931-32 really stand out for being mild, especially 1931-32. During that winter, the upper air trough held over the western U.S. while the east remained in the ridge axis. This pretty much shut off any polar air to the region as a mild southwest flow dominated during the winter.

While there is limited data, it is safe to say the earlier winters were dominated either by a mild zonal flow or upper ridge (possibly the result of a positive NAO). The winter of 1963-64 was an interesting mild winter. The Pacific jet remained quite strong all winter and though the upper wind pattern was further south than on average, the strong winds pushed the milder Pacific air well into the northern half of the country. The south did have a cooler than normal winter and pockets of heavier rain (much like one would expect in a more developed El Niño). Much of the polar air was pushed further east out over the northern Atlantic, only occasionally breaking into the lower 48.

STORM TRACKS

It makes sense that with such wide ranging winter results, the storm tracks would be quite variable in both, location and intensities. In the strongly amplified upper air winters, stormier conditions led to more intense storms and heavier snows, mixed precipitation (including freezing rain) and rain.

As in the majority of winters, whether they be cold or mild, the most predominant storm track continued to be the Alberta Clipper skirting across southern Canada or diving southeast into the northern and eastern U.S. What we will be watching for this winter is for this track to occasionally be the forerunner of major storm development across the Southern Great Lakes, Ohio Valley and East Coast. This storm track development would be one way to set the region up for a stormier winter, especially if phasing occurs between the Arctic Jet and sub-tropical Jet. Of course, the further east the phasing, the less likely for heavier snows in this neck of the woods.

The more common low pressure systems/tracks seen during the snowier winters were the Colorado Low and Texas Low where here too, a phasing of the two aforementioned jets can create some hefty storms. The storms that curved northeast toward the northern Ohio Valley or Great Lakes and were responsible for much of the heavier snows or mixed precipitation here in Southeast Lower Michigan. Speaking of heavy snow and mixed precipitation, the last important storm track that is notorious for bringing that is the Gulf Low, that heads north northeast through the Ohio Valley and into the Eastern Lakes Region or up the East Coast. It is believed that this track could be more active this winter, given the possible upper air scenarios and some of the past winters in the study.

In the milder winters in the study, one of two patterns were seen as prevailing. Either the jet stream over the Pacific turned out to be stronger than normal (and blowing into a broad upper ridge) and ushered milder Pacific air across much of the country, or the deep upper trough held over the west which resulted in the ridge axis settling over the eastern third of the country (as mentioned in the Winter of 1931-32) for the winter.

EPILOGUE

WINTER TEMPERATURES:

Temperature variability, sometimes rather extreme, is strongly suggested not only by this year's research but also by recent trends. That being said, for reasons elaborated in the previous discussed research, the consensus is to go with our strongest indicators of near normal to below normal temperatures for the upcoming Winter of 2004-05. A two-tier temperature outlook is used because of the likelihood of wide variances (a.k.a. roller-coaster pattern) during the winter months. This is not only strongly suggested by the 15 selected winters but also by recent trends. Though some wide temperature swings are expected, in the final analysis, near normal to below normal winter temperature averages are likely.

WINTER SNOWFALL:

Even more challenging than the temperature patterns, season snowfall amounts in the research varied greatly. This was also seen with last winter's research and local results (with snowfalls ranging from much below normal to well above). In this year's researched winters, seasonal snowfalls range from as low the teens (in inches) to as high as the 70s and 80s (and frequently making the top ten lists whether it being top ten snowiest or snowless winters)! Here, our research and recent trends suggests a winter similar to last few winters with snowfalls actually ranging from below normal to above normal... depending on location and storm track. The key here is when and where the dominant storm track sets up. At this time, a slight edge is given to a more southern storm track (similar track to that seen in the Winter of 2002-03).

Therefore, while near normal will be the general (or average) category used for this winter's expected snowfall, snowfall totals are still expected to range from below normal to above normal. If the expected storm track materializes, snowfall should range from near normal to above from the northern suburbs of Detroit south to the Ohio Border, while normal to below is expected further north up across the Saginaw Valley into the Thumb Region.

As the winter unfolds, addition statements and updates will be issued, as conditions warrant. Keep warm and the official calendar winter begins at 742 AM EST on December 21st.

Look for a complete Winter 2002-03 write-up come spring!


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