Indian Monsoon

The monsoon of the Indian subcontinent is one of the most observable and predictable weather reversals on Earth.  During spring and early summer, warm and humid air is drawn northward over the Indian region by semi-permanent low pressure.  The shape of the Indian subcontinent and the peculiar geography of the region, including the tropical Indian Ocean and the cold, dry conditions on the Tibetan Plateau, create ideal heat wave conditions.  Usually by sometime in May, the bubble bursts and widespread heavy rains ensue during the summer.  However, this year, the monsoon has been delayed.  For the last two weeks, weather systems have been diverted eastward or westward away from India.  The result has been two weeks of 115 degree temperatures with sweltering humidity.  Hundreds and hundreds of people have died.  Fortunately, rainy and cooler weather is expected to begin any day now.    Meteorologist John Wheeler

Sea Levels

A new orbiting weather satellite scheduled to launch July 22 is designed to monitor the level of the ocean.  Jason-3, the latest in a joint U.S. and European mission designed to monitor sea level, will use the latest and most sophisticated radar altimeter to send a series of microwave pulses to the ocean’s surface so it can time the reflection.  Jason-3’s predecessors have measured a 2.4 inch average rise in the past 23 years.  But the rise is nor universal.  Most people think of the sea-level as being the same all over, but it is not.  Regions of the oceans that are relatively warm compared to their surroundings swell due to thermal expansion whereas colder regions contract.  These hills and valleys can vary by as much as six feet. By monitoring the height of the ocean around the world, we will be better able to track changing ocean currents as well as improve storm surge forecasts during hurricanes and other coastal storms.   Meteorologist John Wheeler

Texas Floods

Flooding in Texas the past two weeks has become symbolic of the concern that the warming climate is contributing to more extreme weather.  Yes AND no.  Yes, it does make sense that a warmer atmosphere will contribute to increased volatility; more heat in heat waves, more rain in wet patterns.  However, it is also the very nature of Texas weather to go from drought to flood.  Texas is uniquely positioned geographically for huge swings in precipitation.  Western Texas is arid, nestled up against the southern Rocky Mountains which catch whatever is left of any moisture coming across from the Pacific on the subtropical jet stream.  Southeast Texas is wet, straddled against the warm and humid Gulf of Mexico.  A stalled out weather pattern tends to favor one extreme or the other.  That being said, the potential contribution of the warming climate should not be ignored.  Nor should it be considered the only factor.  Meteorologist John Wheeler

Where’s the Flood?

In the space of thirteen days, from May 6 to May 18, Fargo Moorhead’s annual precipitation total to the date went from the 17th driest on record to the 15th wettest .  The 5.82 inches of rain that fell those thirteen days alone would rank in 8th place on the list of wettest Mays.  And yet there was hardly any river flooding in the entire region.  Sure there has been some minor lowland flooding in the typical flood prone areas, the sort of flooding that is common after heavy rain.  But nowhere in our region has there been any of the significant flooding one would expect following such a rain.  Most of the fields that had standing water for a few days have dried nicely, suggesting additional water storage capacity if needed.  We can thank the fall-winter-early spring drought for this.        Meteorologist John Wheeler

Rain and Heavy Rain

Rainfall and heavy rainfall go together.  That is, when there is a pattern of above-average and more frequent rainfall, it is also more likely that there will be a downpour.  Warm weather and heavy rainfall also go together.  When the atmosphere is warmer, there is more capacity to hold moisture in the air, which increases the potential for downpours.  As the average temperature in our region has risen since the middle of the 1900s, so has the frequency of heavy rains.  Also, as the average annual precipitation began to rise in the 1990s, the downpours have been increasing.  The flooding problem across our region the past 20 years can be tied to both of these trends.  The future of flooding in our region is likely going to be tied to both of these trends.  Additional warming appears likely but a further increase in annual precipitation is probably less likely.   Meteorologist John Wheeler

Rising Seas?

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

California Drought

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

Hurricane Forecast

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

Very, Very Cold May

The cold weather earlier this week prompted many inquiries as to the relative unusualness of having snow and temperatures so cold in the middle of May.  Fargo did set a daily record cold maximum temperature Monday at 40 degrees.  Old record was 44 set in 1890.  May snowfall is also rare, but not without precedent.  I would describe such weather in our region as rare, but not unusual; the sort of thing that happens every few years or so.  The most unusually wintry May weather on record in the Fargo Moorhead area was in 1907.  There was measurable snow in Fargo on four separate days; the 2nd, 13th, 14th, and 19th; for a total of 4.2 inches.  The first ten mornings in May were all in the 20s (except for May 2 when it was 17).  There were three more hard freeze mornings on the 14th, 20th, and 27th.      Meteorologist John Wheeler

Drought Beginnings and Endings

 

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