Stuck in a Cool Rut

A July with no 90s? According to Pete Boulay at the MN State Climate Office that hasn't happened since 1994. Come to think of it there were no 90s in July in either 1992, 1993 or 1994. So it's unusual, but not unprecedented. You have to go back 15 years to find a similar (almost comfortable) July.

MSP Almanac

July temperatures for MSP: 3.2 degrees cooler than average (so far).

Only 1.52"of rain has fallen on the metro area so far in July. A mere 9.48" of rain has fallen on the Twin Cities since January 1. Last year 12.87" of rain had fallen as of July 27. According to long-term National Weather Service records we should have seen 16.97" of rain in the metro area as of this date, a nearly 7 1/2" rainfall deficit which explains the severe drought conditions across most of the area.

WRF/NMM Model for 7 am Thursday morning, showing predicted accumulated rainfall between 1 am and 7 am Thursday morning. Significant rain is possible over central and southeastern Minnesota ahead of the next reinforcing cool front, the best chance of some 1-2" amounts south and east of the Twin Cities. We're still in a severe drought spanning the entire metro area, so a midweek soaking would be just what the Weather Doctor ordered.



Nobel Physicist Nils Bohr was reported to have said, "Prediction is very difficult, especially if it's about the future." Amen to that, brother. I would add, "Forecasting is the art of saying what will happen, and then explaining why it didn't." Nobody intentionally deceives or lies, mind you. We are paid (some of the time) to read the tea leaves and give it our best shot. The Weather Machine is a complicated beast, hot air over the tropics surging northward; far less direct sunlight leaving the poles in the cold, numbing air advancing toward the equator. The spinning of the Earth on its axis gives storms their counterclockwise spin (Northern Hemisphere), the most outrageous storms forming along the sharpest contrasts in temperature, as a rule. We're still learning how fluctuations in ocean water temperature can create a domino effect thousands of miles downwind. Now El Nino is returning, but that's no guarantee of a milder than average winter for Minnesota. Most El Nino warming trends correlate with milder, drier winters in the Midwest, but we're learning that not all El Nino's are created equal.

The weather is, by definition, variable - changeable - sometimes severe, but there's ample evidence that the day to day changes are becoming more extreme over time. For much of July we've been 3-4 degrees cooler than average, but the Yukon (far northwest Canada) has seen day after day of baking 80s, even some low 90s. I've seen 40s north of the Arctic Circle, the result of persistent high pressure over the North Pole and much of Siberia, where highs have been well above average, reaching the 70s and 80s. Just Monday an exceedingly rare tornado slammed into Tokyo. Click here to read the latest on this (apparent) Kansas-size tornado that destroyed at least 160 homes. There is actual video of the tornado (about :25 in on this clip, which is in Japanese, but you definitely get the drift). Again, one storm, one heat wave, even one month or one year doesn't prove anything. It's the frequency over time, over long periods of time, stepping back and looking at the macro trends. That's when you start to scratch your head and wonder what's really happening out there.

We cool off today, highs in the mid 70s with a dip in humidity and a fresh northwest breeze. With the exception of Friday, temperatures will average 5-10 degrees below normal through much of next week, a cool trend into the first week of August. The best chance of rain/storms? Late Wednesday into Thursday morning, more instability (late PM pop-up) showers possible over the weekend, especially over the northern third of Minnesota, where highs may not climb out of the 60s Saturday and Sunday. The "free air conditioning" rant is starting to have a hollow ring, some Minnesotans are ticked off that we didn't see any real Dog Days this summer, no extended stretch of hot, sweaty, pool-worthy days. That may be true, so as soon as I finish my update here I'm clicking over to a travel site.

Does Delta have any non-stops to the Yukon?


Weather Information Table

Precipitation and Temperature Summary for 7/20/2009 through 7/26/2009

               Temperature           Precipitation           G D D
          High Low Week Depart   Week  Depart From Norm  Since Depart
                   Ave   from    Total Past Four  Since   May   from
                         Norm          Week Weeks  4/1      4   Norm

Aitkin          78  41  58.8  -8.2    3.42  2.36   .17  -1.24   881   -70
Forest Lake     80  50  62.9  -8.2     .38  -.63 -1.76  -7.38  1128   -77
Hinckley        75  41  58.0 -10.3    1.99   .97  -.82  -5.08   863  -135
MSP Airport     82  53  66.4  -7.1     .04  -.85 -2.67  -7.17  1269   -44
St. Paul - UofM 79  50  64.3  -8.6     .06  -.91 -2.96  -8.91  1230   -55

Temperatures last week ran 7-10 degrees cooler than average for the third week of July. Hinckley was chilliest, reporting a week with temperatures more than 10 degrees cooler than what they should be. Moisture was fickle: only .04" at MSP International Airport, while 3.42" of rain soaked Aitkin. Since April 1 St. Paul is showing a nearly 9" rainfall deficit; generally east metro is drier than west metro. The column on the far right is "Growing Degree Days", the cooler weather means plant growth is generally not as far along as it should be by the end of July. There is a wealth of information at the USDA National Agricultural Statistics Service. Click here to see the latest information (week by week) for Minnesota.