Chicago’s 56-degree high tied May’s coolest reading—but the lakeshore area bore the
brunt of the chill. Highs reached just 44 degrees in Highland Park and in Wrigleyville,
and 46 degrees at Wilmette and Glencoe.

TUESDAY’S HIGH TEMPERATURE IN CHICAGO REBOUNDS TO THE 70s

Highs surge 18 degrees Tuesday to 74 degrees—a reading likely to be the warmest of
the coming seven days. The overall pattern continues to be cool over the next two weeks.

Dear Tom,
Are tornado warnings ever issued for funnel clouds?
-Patricia Nesbit

Dear Patricia,
A meteorologist would not hesitate to issue a tornado warning based on a
funnel cloud if the report appeared to be reliable and could be associated with a
Doppler radar that shows a rotation in the clouds in the area.
A funnel cloud becomes a tornado when it hits the ground. During periods of severe
weather, it could only be a matter of seconds before a funnel reaches the ground and
starts causing damage.

Storm spotters and weather professionals often use the redundant phrase “tornado on
the ground” to convey a sense of urgency and danger to the public about an
approaching twister. The redundancy makes it clear that the storm is an actual tornado
and poses an immediate threat.

A STEAMY MOTHER'S DAY IN FLORIDA

In contrast to Chicago's rainy chill, record heat gripped the Sunshine State. Record
highs were established in many areas, ranging from 93 at Pensacola to 96 at Miami
and Ft. Lauderdale.

TWISTERS STRIKE EASTERN CAROLINAS

Severe weather continued Sunday evening with tornado damage and injuries reported
in eastern North Carolina near Elizabeth City and Morehead City and in South Carolina
near Charleston.

--By Steve Kahn, WGN Weather Center Meteorologist

More than an inch of rain is likely to fall in many locations in heavy downpours before
the rains diminish to light showers in the afternoon. High temperatures will struggle
to reach the lower 50s, and as strong northeast winds gust in excess of 40 m.p.h. in
the afternoon, readings should drop back into the 40s, making 2008 the coolest
Mother’s Day here since a 50-degree high back on May 12, 2002.

DEADLY TORNADOES SWARM SOUTHWEST MISSOURI

Numerous tornadoes struck southwest Missouri late Saturday. Early reports indicate
three were killed, with many injured and extensive damage. Towns hit included
Neosho, Newtonia and Seneca.

Dear Tom,
What is the difference between a hurricane, a cyclone and a typhoon?
—Jessica Vega

Dear Jessica,

There is no difference. Unfortunately, meteorological jargon and popular usage
variously apply different or overlapping meanings to those three words. In
meteorological parlance, a cyclone is a lowpressure system. Hurricanes and typhoons,
too, are low-pressure systems, but they are a specific kind of cyclone—tropical
cyclones (logically, cyclones that form in the world’s tropical and subtropical zones).
Hurricanes (in the Atlantic Ocean), typhoons (western Pacific Ocean) and cyclones
(Indian Ocean and Australia) are different names for the same type of storm. In
popular usage in the United States, “cyclone” is applied loosely to tornadoes,
waterspouts, dust storms, hurricanes and even to any strong wind.

Pavement, buildings and other waterproof surfaces cover a large portion of the land in urban areas like metropolitan Chicago. That means rain water cannot soak into the ground. Instead, it gushes into storm drains that discharge directly to local rivers and streams.

About 55 percent of rainwater that falls on a city runs off (and in intensely urbanized locations such as the Loop, runoff approaches 100 percent); only 15 percent of rainfall sinks in to recharge groundwater supplies. The remaining 30 percent evaporates back into the atmosphere.

For comparison, only 10 percent of rain that falls on natural ground cover (forests, wetlands or other natural areas) runs off, and about 50 percent soaks into the ground.

As rainwater runs over city surfaces, it picks up pollutants encountered along the way -- soil, oil and grease from cars, pesticides and fertilizers, pet waste and much more. Not only do such pollutants harm fish and wildlife, they also degrade drinking water supplies and often require that recreational waterways be closed.

What can you do?
If you plan to replace a walkway, driveway or patio in your yard this spring, consider using water-permeable surfaces such as wood decks, spaced bricks or concrete lattice instead of solid concrete or asphalt. These surfaces allow water to soak through to the ground, thereby reducing runoff from your property and helping to replenish groundwater supplies.

The cool weather continues Friday beneath increasing clouds and ahead of an
approaching disturbance that could spark a shower in spots late Friday.

LATEST SOAKER HITS DOWNSTATE

Unwelcome rains drenched the southern Midwest on Thursday. As much as 1.59
inches fell at Freeburg while 1.54 inches was measured at Flora—both east of St.
Louis in Downstate Illinois. The same storm spawned half a dozen twisters across
Tennessee, Alabama and Mississippi. Meantime, still another storm entering the
western Plains produced 68,000-foot-tall thunderstorms responsible for 70 m.p.h.
gusts at Lewis in southwest Kansas.