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Precipitation Summary for August

September 4, 2013

(This is a test post by e-mail)


The Carol Stream area went dry for most of the first 3 weeks of August, with only 2.24" of rain falling from August 1 through August 29.

August 30, August 31 and September 1 brought 2.47" of rain, soaking yellowing yards and bringing the creek to bankfull.

No meaningful rain is expected for the remainder of the week, however.

April 17-18 Storm Summary

April 23, 2013

Storm Total: 5.86″

Effects:

  • Complete flooding of Armstrong, Veterans and Mitchell Lakes Parks
  • Kuhn Road closed
  • Thunderbird Trail remained open
  • Crest approximately 8-10 hours after the heaviest rain ended

On April 17-18, a storm system brought 5.86″ of rain to the area, taking the better part of 3 days to do so. It is difficult to easily establish the clear effects of the storm, as the ground was saturated by 2.60″ of rain in the two weeks prior to the event, reducing amount of stormwater capacity available for flood control for the main event. Still, it can be said that the effects of the storm were less than the July 2010 and September 2008 storms, because of:

  1. The excessively long duration of the rain
  2. The lesser amount of rain that fell in the event.

Hydrology
This was a widespread heavy rain event. This can be seen in the pair of images below, showing heavy rain (in excess of 3.00″, and at least more) extending all the way back to Missouri. By comparison the July 2010 event, while more intense locally, largely did not affect areas south of Interstate 80 and north of Interstate 90.

It is for this reason that area rivers hit numerous record crests, sometimes far exceeding (by feet!) the records set in September 2008. See the links section below.

Somewhat worryingly, this event took place outside of the usual heavy rain “season” (typically between June and September). Heavy rain events are associated with warm temperatures and tropical air masses, and April has not been warm this year. It is for this reason that we should again adjust our expectations regarding the frequency and intensity of heavy rain, and prepare for the next event.

13Apr17_rf mw_precip

Links:

Realtime Event Info – 4/17-18

April 17, 2013

Forecast

  • As of 5:00p 4/16, 2.5-3.0″ of rain is expected (Weather Prediction Center)
  • Rain and thunder chances ramping up significantly after 4/17 7:00a
  • Only 2.25″ in 6 hours required to cause flash flooding (Flash Flood Guidance)
  • Essentially one month’s worth of rainfall is possible tomorrow

Concerns

  • Saturated ground
  • Current Armstrong Park flood capacity reduced (pictures to come)
  • Possibility for more than the forecast amount of rain

Impacts

  • Closed streets

QPF forecast as of midnight 4/1 vs. observed values

See this Google Doc

Quotes

NWS Chicago:

FORECAST PRECIPITABLE WATER VALUES
ARE EXPECTED TO BE VERY HIGH...IN EXCESS OF 1.5 INCHES...WHICH IS
2 TO 3 STANDARD DEVIATIONS ABOVE NORMAL BY WEDNESDAY AND MAY GET
CLOSE TO 2 INCHES BY THURSDAY...WHICH WOULD BE 3 TO 4 STANDARD
DEVIATIONS ABOVE NORMAL. IN OTHER WORDS...THE POTENTIAL FOR
HEAVY/EXCESSIVE RAINFALL IS HIGH.

NWS Quad Cities:

60 KNOT SOUTHERLY LOW LEVEL JET WILL TRANSPORT
EXCELLENT FEED OFF THE GULF WITH PRECIPITABLE WATERS OF 1.50-1.70
INCHES ACROSS THE DVN CWA. THIS IS IN RECORD TERRITORY FOR APRIL AND
PAST CASES WITH THIS VERY HIGH PW`S RESULTED IN EXTREME EVENTS. RAIN
AMOUNTS JUST IN THIS TIME FRAME (NOT COUNTING TONIGHT AND WEDNESDAY)
WILL BE IN THE 2 TO 3 INCH RANGE OVER A WIDE AREA OF THE CWA. ANY
STRONGER THUNDERSTORMS OR TRAINING TAKING PLACE WILL YIELD EVEN
HIGHER AMOUNTS.

Potentially serious flooding situation tomorrow through Thursday morning

April 16, 2013

The Weather Prediction Center is forecasting over 4.00″ of rain over the entire Klein Creek basin tomorrow through Thursday morning. Locally heavier amounts are likely. The ground is saturated, though the creek is below its banks at this time; the current level of water in the north Armstrong Park pool is unknown at this time. Lake George is more full than usual.

This amount of rain at this time would certainly lead to flooding-related complications, including closure of multiple streets, for an extended period of time.

Please review your flood plan and be prepared to take appropriate action.

In addition, severe weather is possible with this system, including large hail and damaging winds.

Storm summary for January 28-30, 2012

January 31, 2013
tags:

Total Precipitation: 2.74″
Greatest One-Day Total: 1/29 7:00a – 1/30 7:00a, 1.84″

Impacts

  • The northern flood pool in Armstrong Park is full, and spreading into the northern baseball field.
  • The Veterans Park pedestrian bridge is under about 3′ of water.
  • Illini Drive had about 2-3″ of water depth near the curbs at Armstrong Park.

Discussion

According to the National Weather Service, our ground was mostly frozen (at depths > 8″ deep) during the event. As a result most of the rain that fell converted directly to runoff. A similar storm in June would cause minimal impacts.

Very fortunately, there was no snow cover on the ground for this storm. In December 2008, over 2″ of water was locked in the snowpack, and another 2″ of rain fell, causing much greater impacts.

No significant precipitation is expected for the rest of the week, into next week.

Moderate drought in place across the region; upgrade to severe drought likely

July 17, 2012
tags:

Moderate drought remains firmly entrenched in place throughout the region. With the jet stream running across Canada and very little, if any, significant weather expected in the next 14 days, severe drought will likely become the norm across northern Illinois.

See the latest drought classification here:

In the local Carol Stream area, we have actually received about 3″ of rain (depending on your exact location) in the last 2 1/2 weeks. This is about an inch shy of the average precipitation for the month of July (4.01″) and has helped lawns throughout the village green up.

Supplemental watering is recommended, however, as an extended period of dryness in the next month is likely.

Long, quiet period to end this weekend

April 11, 2012

After a warm, relatively dry winter, with enough periodic rains to keep us from drought, significant rainfall is possible this weekend.

Various models are predicting anywhere from one to four inches of rain in the Friday-thru-Tuesday period, while others are predicting two to five inches of rain. Higher totals would be problematic in spite of the overall dry weather we have so far experienced this spring.

Stay tuned to the latest National Weather Service forecasts, starting Friday.