Although the interior of the Antarctic continent is getting colder, one of the most rapidly warming locations on Earth the past few decades is along the Antarctic Peninsula. An ice shelf known as Larsen C, the fourth largest ice shelf in the world at more than 20,000 square miles, adjoins the Antarctic Peninsula and has been discovered to be melting at a rapid rate due to the warmer air temperatures and the warmer seas underneath. A research team from the British Antarctic Survey has reported a growing crack in the shelf which could cause it to break up some time in the next 100 years. This would not lead directly to a rise in sea levels because this ice is already floating in the ocean. However, if the region continues to warm, the loss of the ice shelf could allow glaciers presently land locked to melt into the ocean faster. Sea-level rise is one of the greatest concerns associated with Global Warming. John Wheeler
Tree ring analysis suggests the present drought in the Southwestern U.S. may be the fourth most severe in approximately the past 1000 years. The nation’s two largest reservoirs, Lake Powell and Lake Mead, both on the Colorado River, are at their lowest levels since construction. These two impoundments provide much of the water needs for desert metropolises such as Las Vegas and Phoenix. This melted snow also provides considerable water for the Los Angeles Basin and the California agriculture industry, which is where a large portion of America’s grocery store produce is grown. The lakes are at approximately 40 per cent of capacity this spring, and will drop more over the summer. Hopefully, next winter’s El Nino will help generate an above-average snow pack in the Rockies next winter or the situation will continue to worsen. Meteorologist John Wheeler
There are three major, large-scale factors which can have large scale effects on the Atlantic hurricane season. One is the general sea-surface temperature. If the tropical part of the Atlantic Basin is warmer than average, there is more thermodynamic energy available for hurricanes. Another is the amount of dust from the Sahara. Actually, it isn’t the dust, but the deep layer of dry air which accompanies these dust clouds that rob tropical storms of moisture. The other key is the overall strength of upper level winds. When the winds aloft are strong, tropical storms tend to shear apart before they can grow large and powerful. The presence of a building El Nino such as there is at present often produces stronger winds above the Atlantic, usually signaling a quieter Atlantic hurricane season. Meteorologist John Wheeler
It was just one week ago that it started raining. Rain over the seven days since has been plentiful enough to eliminate all concern about it being dry. It is interesting to note that our weather condition can switch from dry to wet in such a short time. On the other hand, it cannot switch from wet to dry so quickly. Of course, it can stop raining tomorrow, but the lingering effects of recent rain will keep the soil soggy and the grass growing for some time. The winter drought began last September 5. That was the day after the last heavy rain of 2014. We were in a drought through the fall because the drier weather caused us no problems. The drought really began to manifest itself this spring with agriculture’s need for germinating rainfall along with a rash of grass fires. Now suddenly, all that is over. I wonder when the next drought will begin. Tomorrow, perhaps?
Meteorologist John Wheeler
The average daily high temperature is not meant to be a reflection of what the temperature is supposed to be. Rather, it is the average of all the daily highs over a period of record. So with that in mind, the average daily high has now reached 70 degrees for the first time since September. There have already been 17 days with a high temperature of at least 70 degrees this year. The first was back on March 15. It happened 11 times during a warm, dry April. The warmest has been 87 degrees on May 2. We had a lot of warmer than average afternoons from mid-March through early May due to the early snowmelt and exposed dry soils. Now that the ground is wet, it will become a little harder to get so many above average afternoon temperatures. Unless, of course, it stops raining again and the ground becomes dry. Meteorologist John Wheeler
Is our warming climate effect the threat of tornadoes and severe thunderstorms? From the political sides of this debate, this question can be quickly and easily answered either “Yes!” or “No!” depending on the politics. In the real world, the answer is a lot trickier. The trend across the United States in recent decades is a decrease in the overall number of tornado days along with an overall decrease in the quantity of tornadoes. But coupled with this decrease in bad storms is an increase in those few terrible tornado outbreak days, those days when dozens or even hundreds of tornadoes causing staggering property damage and loss of life. So although severe storms are not exactly increasing, their variability is. Some of this statistical clustering is skewed by the year, 2011, when several huge tornado outbreaks swept the Midwest and South. Ongoing research offers no consensus yet of how tornadoes will be affected by climate change in the future.
Meteorologist John Wheeler
I had an inquiry earlier this week about the difference between a rain shower and just plain rain. The classic meteorological definition is that a shower is brief and/or intermittent whereas rain is steady. But there is no specific time limit for when a shower crosses the threshold and becomes just rain. For most of us in the business of forecasting, a shower differs from rain by being convective in nature. This means that showers are caused by smaller scale updrafts of air and so are briefer or more intermittent than a general area of rain which is caused by a general, gradual rising motion over a large area. But here, also, there is no cutoff at which rising air is of too large of a scale to be considered a shower-making updraft. In general, if it is brief, short, or longer but highly variable in intensity, it is a shower. Meteorologist John Wheeler
It took one storm exactly two days to take eastern North Dakota and western Minnesota from too dry to plenty wet. This is often how it works in spring because of the fact that average precipitation through fall, winter, and spring is just not that much. The six months of November through April produce just a fourth of our average annual precipitation. So if those six months are very dry and we get just half of the average, we can make it up with one good rain storm like the one Sunday and Monday. Warm season precipitation is the important stuff. If we were to go from May through October with half of average rainfall, the moisture deficit would be more than eight inches which would cause much more of a problem and would be much harder to make up. So the weather picked a good time to go dry this fall, winter, and early spring. Meteorologist John Wheeler
How many people remember that the temperature reached 15 degrees just last Thursday morning? How many remember the fact that that was the third of three consecutive mornings below freezing? If you have forgotten these cold, hard facts, then you should be reminded of them before you go too far in planting sensitive annual flowering or vegetable plants outside. It is actually possible that last Thursday will be our last freeze of the spring. What a spectacular statistic it would be for the final freeze of the season to be 17 degrees below freezing. However, it is far more likely that our region will have freezing mornings again, perhaps more than one. Our dry soil combined with the dry weather pattern favors large temperature ranges during clear weather. And this increases the likelihood of a late-season freeze. However, there is another fact you might have forgotten. The average last 32 degree temperature is May 8. Of course, if you are willing to cover your plants on cold nights, then plant away.
Meteorologist John Wheeler
There have been several inquiries into the WDAY Weather Center office lately about how unusually windy the spring has been. April is, on average, the windiest month of the year, with an historical average wind speed of 13.9 mph for the month. This number may seem low, but consider that April nights are not usually very windy so a lot of that average wind speed comes from very windy afternoons when the sun is shining down on bare, black soil creating turbulence. Well, the average wind speed so far this month has been about 13.9 mph; exactly the average. However, over the previous five years, the average April wind speed in Fargo Moorhead is 12.0 mph; considerably below average. So it turns out that this spring is closer to the long term average for wind. But a run of calmer Aprils has skewed our memories.
Meteorologist John Wheeler