Updraft: April 21, 2010 Archive

Dryness spikes fire danger and pollen count

Posted at 8:40 AM on April 21, 2010 by Paul Huttner
Filed under: Fire weather, Pollen

Our dry, pleasant weather pattern comes with a price this spring.

Pollen in much of the Upper Midwest is off the charts this week. The combination of this early spring bloom and lack of rainfall to wash the air clean has sent pollen levels skyrocketing.

According to daily pollen samples from sensors deployed by the Clinical Research Institute (CRI) in Minneapolis, we are breathing in 454 grains of tree pollen per cubic millimeter of air. That's a lot of pollen in one breath.

Other sources like pollen.com put our pollen count at a 9.3 on a scale of 1 to 12. According to pollen.com our predominant tree pollen is elm, poplar and alder. You don't need a genius to know your elm trees are spewing pollen. The weather lab spruce trees are also sending showers of pollen into the air. One brush of the hand sends a cloud of pollen skyward.

CRI defines pollen seasons in Minnesota this way:

There are typically three pollen seasons in Minnesota, with some overlap of pollen types.

-Tree pollen is present from early April until the end of May.

-Grass pollen is present from early June to mid-July.

-Weed pollen is present from mid June until a hard frost occurs. Ragweed (one of the more allergenic weeds in the area) typically pollinates from early August through mid October.

Outdoor molds can be present year round, with higher concentrations from spring until snow cover again in the late fall/early winter.

April showers usually wash our air clean every few days. It's been nearly a week now since we've had rain in southern Minnesota, and much longer in the north. Look for pollen counts to remain high until the weekend when we could wash the air with some rain in southern Minnesota.

Fire weather:

The dry breezy weather mans fire danger is high today. The dew point in Minneapolis is in the low 30s Wednesday morning. It's 49 in the middle of the Sonoran Desert in Tucson, Arizona. That means there's considerably more moisture in the air in the Arizona desert than there is in Minnesota today!

The NWS Defines fire weather as a combination of:

-Dry fuels like grasses and brush on the ground.
-Low relative humidity
-High winds
-Mild temperatures

MN DNR fire danger map.

The combination of these factors are all in place today in Minnesota. Look for any fires that start today to spread rapidly toward the southwest on breezy northeast winds...and to make your local newscast tonight.

PH