Jeff Andresen...On Monday, September 21, showers and thunderstorms associated with the weather disturbance that brought extended heavy rain and flooding to much of the south and Ohio Valley during the past week ended an extended period of mostly sunny, dry weather across Michigan. Many areas had been dry since August 30. Forecast guidance is now suggesting some major upper air changes during the upcoming week leading to a cooler, more unsettled weather pattern.

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Jeff Andresen...A nearly stationary area of low pressure across the Ohio Valley will bring a continuing chance for showers across southern sections of the state during the next couple days while mostly fair and dry weather continues across the north. In a somewhat unusual fashion, moisture moving from east to west from the Atlantic will wrap around and back into Michigan through Thursday, September 10. Rainfall with this system is expected to remain on the light side with daily totals generally in the 0.25-0.5 inch range where rain occurs.

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Beth Bishop...Check out the overnight temperatures tool at www.enviroweather.msu.edu. This tool displays overnight temperatures recorded by area weather stations during the previous night. It also shows forecasted low temperature for the upcoming night. Late afternoon/early evening dewpoints are also provided.

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Jeff Andresen...A major change of the jet stream pattern to western troughing to eastern ridging brought above normal temperatures and heavy, widespread rainfall to much of the state during mid-August. That eastern ridging pattern was replaced by a trough once again during the last few days, bringing relatively cool, Canadian-origin air into the Great Lakes region.

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By Amy Irish-Brown... For the weekend of August 8, there were several heavy rain events that occurred without hail or high winds. Rainfall totals for the general Sparta area were between 3.5 and 4.5 inches for the entire weekend. On Sunday, August 9, at about 6:30 PM a storm system moved very quickly over The Ridge.

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By Jeff Andresen... A slow-moving frontal boundary edging through a very humid air mass led to widespread heavy rain across much of Michigan and the Great Lakes region this past weekend, August 7-9. The rains eased dryness and moisture deficits that had accumulated during the past several weeks.

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By Jeff Andresen... The upper air pattern that has dominated weather conditions across the Great Lakes region so far this summer, ridging (and excessive heat) across western North America and troughing (and cooler than normal temperatures) across central and eastern sections, will likely continue for the next one to two weeks. For a forecast, this generally translates into more cooler than normal temperatures.

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Jeff Andresen...The dominant upper air pattern of the past few weeks, ridging across the intermountain west and High Plains with troughs across the far west and eastern United States will continue to influence weather across the Great Lakes region through the remainder of the week at least. With the main axis of the ridge expected a bit further west this week, northwesterly flow and cooler than normal conditions are likely in Michigan through next weekend.

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By Jeff Andresen... What a difference a week makes. Since late last week, the large upper air ridge that brought heatwave conditions to much of the Midwest and South weakened and moved westward into the western United States. (Note recent 95*F-plus high temperature readings in many interior sections of the West).

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By Jeff Andresen... Almost as if on cue with the beginning of astronomical summer (solstice was June 21), a large upper air ridging feature formed across central sections of the United States during the past few days, bringing the first major heat wave of the summer season.

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By Aaron Pollyea... Forecast guidance shows a short wave upper air feature moving through the region on Wednesday, June 17, bringing precipitation to the state. Precipitation should be state-wide, but higher amounts in the southern areas of the state.

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By Jeff Andresen... The cool front that brought heavy rain to much of Lower Michigan Monday, June 8, will move south and east of the state before stalling out across the Ohio Valley by late Tuesday, June 9.

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By Jeff Andresen... The cool frontal that moved through Michigan Tuesday, June 2, will stall out just south of the state then edge back northward on Wednesday, June 3. A weak area of low pressure moving along the front will bring widespread rain to southern sections of the state overnight Tuesday through Wednesday morning.

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By Jeff Andresen...The area of low pressure with tropical origins that brought torrential rains and flooding to much of Florida last week will merge with a cool front across the Upper Midwest and move through Michigan Wednesday, May 27, and Thursday, May 28. This system will lead to widespread rainfall across most of the state, including northern sections missed by rainfall earlier this month.

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By Jeff Andresen...A weak frontal boundary across northern sections of Michigan Tuesday morning, May 19, will move northward as a warm front and allow a major warming trend across the state accompanied by strong southwesterly winds. A cool front will move from northwest to southeast across the state Thursday, bringing the chance for showers and cooler temperatures for the end of the week.

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By Jeff Andresen...A cool and unusually dry airmass – dew point temperatures less than 20F and daytime relative humidities less than 25 percent – brought frost and freezing temperatures to some sections of the state on the mornings of May 10, 11 and 12. This airmass will move eastward and out of the region by late Tuesday, May 12.

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By Jeff Andresen... Frost and freezing temperatures are a major concern for growers during the spring season. The last freezing temperatures of the spring season occur on average from the last few days of April in extreme southeastern sections of the state to early and mid-May over most of the Lower Peninsula to early June in interior areas of the Upper and northern Lower Michigan.

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By Jeff Andresen... The area of high pressure that brought fair, spring-like conditions to Michigan during the past several days will drift east and out of the region by late Tuesday, May 5. A series of weather disturbances will move across the Midwest on an almost daily basis through Friday, bringing mostly cloudy skies with several chances for rainfall.

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By Jeff Andersen... A split flow jet stream pattern with troughing across the western United States and ridging across western Canada continued during the past week, leading to an active weather pattern across Michigan and the Great Lakes region.

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By Beth Bishop... Spring weather in Michigan is usually a mix of summer and winter, and delicate fruit crops can be at risk of injury from low temperatures. Enviro-weather has a tool that helps fruit producers protect their crop by determining if freezing temperatures have occurred overnight and predicting if they might occur the following night.

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By Beth Bishop... Spring has finally arrived. Despite recent snow, signs of the upcoming growing season are all around. Enviro-weather has been updated for 2009 with a new look and some new tools.

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By Jeff Andresen... If the past winter seemed unusually long and cold, your weather senses are right on the money. A high amplitude jet stream pattern characterized by large troughs across western and central North America set up just before Thanksgiving last fall and persisted into early March.

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Bill Shane and Tracy Aichele...A model for sooty blotch and fly speck, an important disease for Michigan apple and pear growers, has just been added to Enviroweather (www.enviroweather.msu.edu), a Michigan State University web site weather-based system for making pest management decisions.

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By Nikki Rothwell, George Sundin, Bill Shane and Amy Irish-Brown... Growth of the fire blight pathogen is favored at temperatures over 65ºF. Degree hours using a base of 65ºF (DH65) are used to estimate fire blight bacterial population growth.

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By Tracey Aichele... After a few weeks of warm weather and relatively quick degree-day accumulation, a low-temperature event may have affected crops throughout Michigan.

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Jeff Andresen...Scattered showers and thunderstorms brought some much needed rainfall to a few locations across Michigan during late July, but the rainfall was localized and drought conditions persist in many areas of the state. For the growing season thus far (beginning April 1), precipitation deficits have grown in many areas to the 3-5 plus inch range, although these figures are somewhat misleading since the majority of the drier than normal conditions have taken place since early June when crop water needs are relatively greater. Normal precipitation for this time frame is on the order of 11.5-13.0 inches.

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Mark Trent...Use weather summaries at www.enviroweather.msu.edu that include growing degree-days (GDD) to get GDD accumulations for the entire year-to-date. The summary automatically generates a report showing data from April 1 first through the current date. Even though the report begins April 1, the GDDs are calculated from January 1. To get a report that includes all dates or any number of consecutive days between January 1 and the current date, use the “Change date range” option near the top of the page. Remember, all GDDs on these reports are calculated from January 1.

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Mark Trent...Create a shortcut on you desktop to your favorite Enviro-weather report. Here’s an example for users of Internet Explorer. If you are keeping track of apple scab infection periods, go to the apple scab report for your station and right click anywhere on the screen. A menu will pop-up, select “create short” from the menu. The next time you want to access a current apple scab report just open the short cut on you desktop and you will go directly to the report.

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Michigan and much of the country has been hit with warm and cold weather patterns that are keeping fruit growers guessing about the 2007 crop. On this morning’s Fruit CAT Alert team conference call, it was noted that it is too soon to accurately identify the extent of the damage from the recent frost and winds.

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Jeff Andresen and Aaron Pollyea...Unusually hot, humid weather impacted nearly all continental United States during the last two weeks of July and the first week of August. Nationally, more than 2,300 individual daily records for high temperatures were broken as well as 50 new records for the hottest July temperature ever. More than 200 fatalities were associated with the stressful conditions, the majority occurring in California during the initial week of the event. The unusually hot temperatures also led to record or near-record warm mean temperatures for the month of July across the country. July 2006 will go down in the record books as the second warmest on record (since 1895) at 77.2°F, following only July of 1936 at 77.5°F.

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Bill Shane...One of the useful models on the new Enviro-weather web site (www.enviroweather.msu.edu) of MSU is the fire blight model for apple. This model is based on the blossom blight model in Maryblyt™ developed by Paul Steiner (deceased) and Gary Lightner, both formerly of the University of Maryland. Maryblyt™, developed for the older DOS operating system, is no longer commercially available.

I am providing here a brief explanation of the blossom blight model on Enviro-weather for those wanting to understand how to use it more efficiently.

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Bill Shane...The new Enviro-weather web site (www.enviroweather.msu.edu) of MSU is quickly becoming a favorite place to find weather-related information for fruit growers. One of the especially useful features in Enviro-weather for this time of year is the Overnight Temperature Report that gives a quick look at the prospect for freeze damage based on the weather stations in a region. The report provides hourly average temperatures from 10:00 PM of the previous day to 7:00 AM of the current day.

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Frost conditions are upon us as the weather cools down. For specific information on current weather conditions, see Jeff Andresen’s weather column in this issue.

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