Severe potential tonight

1:35am update-

Storms are now about an hour from our western counties. They are exhibiting some weakening but the low level jet is still strong and I will be sticking around to make sure they don’t reintensify or bow out further.

 

11:15pm Update-

Severe Thunderstorm Watch is now in effect for Green, Jodaviess, Stephenson, and Carroll counties until 5am Sunday. We are tracking a large bow echo moving rapidly toward the area through the evening. Low level jet winds are expected to intensify within the next few hours and fuel the storms further. I will be monitoring the situation through the evening.

-AB

 

Thunderstorms will once again be possible through the overnight hours with warm and muggy lows around 70. As of 10:45, I am tracking a line of severe storms from Winona, MN to Ft. Dodge, IA.  They are moving into a favorable airmass and we will keep tabs on the storms as the low level jet ramps up in the next hour or two to fuel them further.  I will be online and on air if need be later on. I expect arrival times between 1am and 3am through our western counties.

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Posted under severe weather

This post was written by Aaron Brackett on June 26, 2010

Severe weather west, heavy rains here

115day1otlk_20001As we saw showers and thunderstorms move through last night, thankfully the Stateline area was spared damaging storms. Despite the strong winds and hail, we did see a good amount of rain come down around the area with gauges topping out near an inch with locally higher amounts. Flooding will continue along the Kankakee, Iroquois, and Illinois rivers to the south but with more heavy rain possible, the concern may shift north once again

-AB

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Posted under flooding

This post was written by Aaron Brackett on June 26, 2010

Severe Thunderstorm Watch

A Severe Thunderstorm Watch has been issued through 3am for Jo Daviess, Stephenson, and Green County. Storms currently in SE Minnesota have been severe and will move southeast this evening. The Storm Prediction Center says the storms will accelerate and possibly produce wind damage in Northeastern Iowa and possibly adjacent parts of Wisconsin and Illinois. Storms will arrive at the Mississippi River around Dubuque at 1am and possibly affect the Rockford area around 3am. Storms should be in a dying phase at that time. -ES

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Posted under severe weather

This post was written by Eric Sorensen on June 25, 2010

Big lunar eclipse tomorrow morning

NASA – This Saturday morning, June 26th, there’s going to be a lunar eclipse—and for many residents of the USA, it’s going to be a big one.

The eclipse begins at 3:17 am PDT (10:17 UT) when the Moon enters the sunset-colored shadow of Earth. By 4:38 am PDT (11:38 UT), the moment of greatest eclipse, 54% of the Moon’s diameter will be covered. From beginning to end, the event lasts almost three hours.

Big Lunar Eclipse (contacts, 500px)

The Moon’s path through Earth’s shadow on June 26th. You can convert Universal Time (UT) to your local time here. Image credit: F. Espenak/GSFC. [larger image]

Although the eclipse is only partial, it will be magnified in size and charm by the “Moon Illusion”–a result of the eclipse occurring close to the horizon from viewing sites in the USA.

For reasons not fully understood by astronomers or psychologists, low-hanging Moons look unnaturally large when they beam through trees, buildings and other foreground objects. In fact, a low Moon is no wider than any other Moon—cameras prove it—but the human brain insists otherwise.

Who are we to argue?

The effect will be particularly strong in western and central parts of the USA and Canada where the Moon will be setting as the eclipse reaches maximum. (Observing tip: Look low and to the west just before dawn.) The fact that the extra size is just an illusion in no way detracts from the beauty.

People in New England and northeastern Canada will justmiss it. The Moon sets shortly before the eclipse begins.

Big Lunar Eclipse (corrected visibility map, 500px)

A global map of eclipse visibility. US readers should note that the eclipse will not be visible from New England and only briefly visible along most of the Atlantic seaboard. Image Credit: F. Espenak/GSFC [larger image]

Halfway around the world, observers in India, Japan, and parts of East Asia will experience the same phenomenon. They’ll see the eclipse on Saturday evening as the Moon is rising. The Moon Illusion will be fully active as Earth’s shadow sweeps across low-hanging lunar terrain.

It almost makes you feel sorry for people living on the dreamy islands of the South Pacific. There the eclipse takes place directly overhead, high in the midnight sky where the Moon Illusion does not work. That’s okay. A partial lunar eclipse is a beautiful thing all by itself.

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Posted under space

This post was written by Eric Sorensen on June 25, 2010

Tropical Depression forms in the Caribbean

depressionThe National Hurricane Center has classified the disturbance in the Caribbean as Tropical Depression #1. This is expected to become a tropical storm within the next day or two. It will come ashore along the Riviera Maya in Mexico and then into the Gulf of Mexico.
Long-range models are hinting at a possible landfall in the Gulf Coast from Houston, eastward to New Orleans. -ES

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Posted under tropical weather

This post was written by Eric Sorensen on June 25, 2010

Hurricane vs. Oil Spill

slickWith tropical weather sure to heat up over the next few days and week it’s time to separate some facts and myths when it comes to the Deepwater-Horizon oil spill in the Gulf of Mexico. 

What will happen to a hurricane that runs through the oil slick?

  • Most hurricanes span an enormous area of the ocean (200-300 miles) — far wider than the current size of the spill.
  • If the slick remains small in comparison to a typical hurricanes general environment and size, the anticipated impact on the hurricane would be minimal.
  • The oil is not expected to appreciably affect either the intensity or the track of a fully developed tropical storm or hurricane.
  • The oil slick would have little effect on the storm surge or near-shore wave heights.

What will the hurricane do to the oil slick in the Gulf?

  • The high winds and seas will mix and “weather” the oil which can help accelerate the biodegradation process.
  • The high winds may distribute oil over a winder area, but it is difficult to model exactly where the oil may be transported.
  • Movement of oil would depend greatly on the track of the hurricane.
  • Storms’ surges may carry oil into the coastline and inland as far as the surge reaches. Debris resulting from the hurricane may be contaminated by oil from the Deepwater Horizon incident, but also from other oil releases that may occur during the storm.
  • A hurricane’s winds rotate counter-clockwise. Thus, in VERY GENERAL TERMS:
    • A hurricane passing to the west of the oil slick could drive oil to the coast.
    • A hurricane passing to the east of the slick could drive the oil away from the coast.
    • However, the details of the evolution of the storm, the track, the wind speed, the size, the forward motion, and the intensity are all unknowns at this point and may alter this general statement.

Will the oil slick help or hurt a storm from developing in the Gulf?

  • Evaporation from the sea surface fuels tropical storms and hurricanes. Over relatively calm water an oil slick could suppress evaporation if the layer is thick enough, by not allowing contact of the water to the air.
  • With less evaporation one might assume there would be less moisture available to fuel the hurricane and thus reduce its strength.
  • However, except for immediately near the source, the slick is very patchy. At moderate wind speeds, such as those found in approaching tropical storms and hurricanes, a thin layer of oil such as is the case with the current slick would likely break into pools on the surface or mix as drops in the upper layers of the ocean.
  • This would allow much of the water to remain in touch with the overlying air and greatly reduce any effect the oil may have on evaporation.
  • Therefore, the oil slick is not likely to have a significant impact on the hurricane

Will the hurricane pull up the oil that is below the surface of the Gulf?

  • All of the sampling to date shows that except near the leaking well, the subsurface dispersed oil is in parts per million levels or less. The hurricane will mix the waters of the Gulf and disperse the oil even further.

Have we had experience in the past with hurricanes and oil spills?

  • Yes, but our experience has been primarily with oil spills that occurred because of the storm, not from an existing oil slick and an ongoing release of oil from the seafloor.
  • The experience from hurricanes Katrina and Rita (2005) was that oil released during the storms became very widely dispersed.
  • Dozens of significant spills and hundreds of smaller spills occurred from offshore facilities, shoreside facilities, vessel sinkings, etc.

Will there be oil in the rain related to a hurricane?

  • No. Hurricanes draw water vapor from a large area, much larger than the area covered by oil, and rain is produced in clouds circulating the hurricane.
  • A tropical storm or hurricane will have the ability to churn the water up so much that the sea-spray will be laden with oil. This will have an impact on areas in a close-proximity to the affected coastline. The impacts of this are not widely known.

(Excerpts taken from www.nhc.noaa.gov/pdf/hurricanes_oil_factsheet.pdf)

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Posted under news, tropical weather

This post was written by Eric Sorensen on June 25, 2010

Severe potential looming to the north

111A moderate risk of severe thunderstorms has been issued by the Storm Prediction Center for today. An impulse from near the Canadian border will move south through the day today. Ongoing rain and thunderstorms overnight will provide energy for new convection to form off of later on today. At this time, the moderate risk extends through Minnesota through east central Wisconsin. A slight risk of severe weather extends closer to home right along the Stateline. The main threat will become damaging straight line winds especially as we go into the late afternoon and evening hours today.

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Posted under weather

This post was written by Aaron Brackett on June 25, 2010

Severe potential to stick around for the weekend

Today will be the last quiet day for a bit as an active pattern will set up for this weekend. Look for temperatures to top out in the middle 80’s today with winds ushering in warmer air out of the southwest. Tonight, temperatures will struggle to fall much past 70 as upper level southerly flow increases. This will prime the atmosphere for a warm Saturday. As for tonight, storms will be possible, especially north of Rockford. Any storms that do develop will have the chance of becoming severe tonight as well as during the rest of the weekend.

114A cold front will swing through Sunday afternoon to bring cooler air for next week, but as it does so, severe thunderstorms will once again be possible. Timing of the front is a key forecast issue. If the front comes earlier, any precipitation that accompanies the front will have less of a severe potential. The later the front comes, the longer we will have to heat the atmosphere ahead of this trigger, thus adding more potential energy to the situation. Eric Sorensen and I will continue to monitor conditions through the weekend.

Next week will be dry and much more comfortable with highs in the lower 80’s.

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Posted under severe weather

This post was written by Aaron Brackett on June 25, 2010

Tornadoes touch down in Chicago suburbs Wednesday night

Read more about why severe occurred in Northern Illinois by clicking here.

Jim Allsopp, Warning Coordination Meteorologist with the National Weather Service, surveyed the damage in the suburbs of Chicago today. Here is his report:
matteston-map
A National Weather Service meteorologist surveyed damage in Elmhurst-Oak Brook, and also in the Matteson-Park Forest area. It appears the damage in the Elmhurst and Oak Brook areas was caused by strong straight-line winds from a line of severe thunderstorms. An EF1 tornado occurred in Matteson and Park Forest.

The damage in Oak Brook was spread out at least a mile wide. Damage consisted of numerous downed tree limbs and uprooted trees. There were signs and poles blown down, and roof damage to office buildings. The most intense damage was concentrated just southeast of the Oak Brook Shopping Center, near 22nd Street and Jorie Blvd.  It appears that trees and debris were all blown down to the south-southeast. Due to the unidirectional debris pattern and the relatively wide swath of strong winds, it does not appear that a tornado occurred. Winds were likely gusting in excess of 90 mph.
In Matteson there was sporadic damage to commercial buildings across a half mile wide path along and south of Route 30 and Cicero Ave. Garage doors were blown in at a service station, and there was damage to roofs and HVAC units on roofs to a few buildings around the Lincoln Mall Shopping Center. There were a few trees blown down in a wooded area just southeast of the mall. A little farther east there was an intense narrow path of damage starting just southeast of the intersection of Lincoln Highway and Governors Highway. The concentrated path went from near Memorial Park to the train platform at Main Street and Hickory. In this neighborhood many large limbs were down and some trees were uprooted. A garage was destroyed and the roof of the train platform was damaged. Winds through this area were likely 90 to 105 mph, which is EF1 on the enhanced Fujita Scale.  The path of the damage was from northwest to southeast, but many of the trees were blown from southwest to northeast, across the damage path. This indicated there was likely rotation. Several residents reported seeing rotation or a funnel cloud in this area. Lighter damage continued southeast of the railroad tracks near Wildwood park and east to the Norwood Plaza at Western and 26th Street. It appears that the tornado dissipated in the forest preserve near 26th Street. The tornado path was about 2 1/2 miles long and about 200 yards wide.
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Posted under tornado

This post was written by Eric Sorensen on June 24, 2010

Canadian fires provide a milky sky here

wildfireDid you notice how hazy it was in our area today? That wasn’t humidity in the air…that was smoke! There are several large wildfires in Saskatchewan blazing out of control right now. These fires are producing a plume of smoke that rises to jetstream level. With a cold front coming through here on Wednesday, our airflow is coming out of the northwest which is bringing the smoke here.

Our air quality remains in the healthy category but areas northwest of Rockford are in the moderate category from Prairie du Chien, WI to Minneapolis. -ES

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Posted under weather, wildfires

This post was written by Eric Sorensen on June 24, 2010