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This is October??
Here it is the middle of October and we have yet to see a typical (or normal) day, temperature-wise. Temperatures have averaged below normal every single day, since the month began, at all three climate locations (Detroit, Flint and Saginaw). Below is the first half of the month’s temperature averages.
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OCTOBER 2009 AVERAGE TEMPERATURES |
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(through the 15th) Dep
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Detroit
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48.5
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-6.5
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FLINT
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45.4
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-6.8
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SAGINAW
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46.2
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-6.3
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Looking over our cold records for the first half of October shows while we are definitely cold for early October, it has been worse (except at Flint but then again 4 out of 5 coldest records for Detroit occurred before the record period at Flint). Have heart, warmer more moderate October weather is expected this upcoming week, anyway.
DETROIT FLINT SAGINAW
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Our autumn outlook analogues painted a nice, warmer than average September but deteriorating conditions mid-late fall (October-November) with colder than average temperatures prevailing. Check out the October temperatures and averages for all three sites (below normal highlighted in yellow and blue against the normal (gray)).
DTW FNT MBS
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Oct
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Oct
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Oct
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1896
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47.7
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1911
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50.9
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48.4
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1918
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55.6
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53.0
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1925
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44.5
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42.5
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40.6
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1957
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50.8
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47.4
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48.0
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1965
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51.3
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49.4
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49.6
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1972
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47.3
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46.2
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43.7
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1976
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47.4
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46.8
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46.4
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1986
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52.6
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50.5
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49.3
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1991
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54.8
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52.8
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50.9
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2002
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50.0
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47.7
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46.2
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Ave
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50.3
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47.9
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47.6
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NORM
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51.9
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49.2
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49.5
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Interestingly, these set of analogues actually mimic the summer analogues where generally normal to below normal weather prevailed. Actually, inspecting the individual months closer, shows more typical fairly nice early autumn weather with around normal temperature (but with the risk of earlier frosts/freezes). Actually, a decent amount of Septembers /5/ show above normal temperatures. After, the preference turns toward normal to below normal mid or late autumn. Probably one of the most anticipated trend I expected to find was the likelihood of an earlier frost and or freeze this year. Why? Simply put, the aggressiveness and persistence of the Polar Jet stream this past summer over Eastern Canada can’t be ignored. This pattern is also reflected in the dominant negative NAO seen this summer (and last winter). Generally, it was found the heavy frost /5th/ and freezes /14th / occurred about a week .
A widespread freeze occurred last weekend (10th) right between the average dates 5th and 14th found for this fall for frost and freezes.
Below /A/ is the composite of all (11) the analogue Octobers and /B/ a composite of the 5 coldest analogues. Note the huge below departures out west of the Great Lakes. After, look at the past week over the same area /C/ from the Midwest and plains into the Great Lakes.. Of course, this below normal departure data shown here represents only the first half or last seven days of October and more moderate temperatures are expected next week. There were only 3 Octobers out of the 11 that averaged above the 51.9 ave at Detroit.
A B
C
Below this /D/ are the Novembers that followed the coldest Octobers in the analogues.
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-Deedler
