Summer Climate Outlook - June Through August 2008
June – August 2008
1. June through August Climatology:
The overall average temperatures over southeast Wyoming and the western Nebraska panhandle reach their average warmest readings of the year during this time…typically in the late July into early August time period. Average low temperatures across the region east of the Wyoming mountains rise from the lower 50’s in June to the mid 50’s to around 60 degrees in July and August. Average high temperatures rise from the mid 70’s to the lower 80’s in June to the mid 80’s to around 90 degrees in July into August. For locations like Laramie and Rawlins, average lows rise from the lower 40’s in June to the mid 40’s to around 50 in July and August, while average highs rise from the mid 70’s in June to the upper 70’s to mid 80’s in July and August. 2. Current situation:
The event known as La Nina continued to weaken during the months of April and May, as depicted in Figure 1 below: A transition to neutral conditions appears likely during the June through July time period. Figure 1: SST and Anomaly
Typical La Nina effects for southeast Wyoming and the Nebraska panhandle are not well pronounced, especially now that summer is approaching. There seems to be little if any correlation between La Nina and temperature/precipitation anomalies in this area.
Drought Status: Overall drought conditions have shown some improvement across the region during the springtime. The snowpack over the mountains has been melting and sent some generous runoff down rivers and streams, and resulted in some minor flooding for a time along a couple of rivers, such as the Little Snake River. Much of the area’s drought status improved to either normal conditions to abnormally dry conditions. There is now only a relatively small area of severe drought condition (hydrologic in nature due to low reservoir levels) over the northern Nebraska panhandle, as can be seen in Figure 2 below: Figure 2: May 27, 2008 Drought Status
The latest drought status and more information can be found at the National Drought Mitigation Centers website here: http://www.drought.unl.edu/ June through August Outlook:
The Climate Prediction Center’s three month outlook for this area indicates an enhanced chance for above average temperatures across this area, as depicted by Figure 3 below. Figure 3: June – August 2008 Temperature Outlook For the Nebraska panhandle and southeast Wyoming area, there is about a 35 to 43 percent chance that overall average temperatures for the period will be above average. Conversely, there is about a 24 to 31 percent chance that overall average temperatures will turn out below average.
The local downscaled temperature outlook, which provides the temperature outlook for more specific sites as opposed to a general area, shows a greater likelihood for above normal temperatures across southern Wyoming, with essentially equal chances over the northern and eastern Nebraska Panhandle. Specific probabilities for selected locations in this area are shown in Table 1:
Location
Probability Above Normal
Probability Near Normal
Probability Below Normal
Cheyenne
69%
23%
8%
Laramie
50%
31%
19%
Medicine Bow
50%
31%
19%
Scottsbluff
47%
32%
21%
Sidney
33%
34%
33%
N. Neb. Panh.
33%
34%
33%
Table 1
More information on the Local 3 Month Temperature Outlook can be found here: For precipitation, the latest outlook indicates that there is about a 33 to 38% percent chance that rainfall during the period will turn out below average, as depicted in Figure 4 below:
Figure 4: June – August 2008 Precipitation Outlook
The latest drought outlook (see Figure 5 below) indicates that the current drought situation over the region is not expected to change significantly during the summer, with drought conditions persisting where it currently exists. Figure 5: Seasonal Drought Outlook
Average total rainfall east of the mountains ranges from about 2.2 to 3.2 inches in June, with the higher amounts over the Nebraska panhandle, and then drop off to about 1.2 to 2.0 inches during August. Laramie and Rawlins average about 3/4ths of an inch to about 1.4
inches of rainfall in each of the three months.
More information can be found at the Climate Prediction Center’s website here:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html
http://www.weather.gov/climate/calendar_outlook.php?wfo=cys
Issued May 15, 2008
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