09.24.10

Fall Flooding and Cooler Weather

Posted in Tropical Weather, Weather News at 3:54 pm by Rebekah

Check out this 18Z (1pm Central Daylight Time) surface analysis from the Hydrometeorological Prediction Center (click to enlarge).

There’s an extratropical cyclone just north of Lake Superior, and a cold front extending southwestward through southern Oklahoma. The low pressure system brought lots of rain to the upper Midwest, and is causing flooding problems in Minnesota and Wisconsin.

NWS rainfall and flooding reports here.

Dramatic news footage of a bridge wiped out in Minnesota.

Cooler air is still to come, behind another cold front that is forecast to make it through Oklahoma Saturday night. This front will bring much more fall-like temperatures to the central and possibly eastern US. The NWS forecast low for Norman on Sunday night is just 51 °F!

Note also that Tropical Storm Matthew is on the map; it’s just now making landfall in Nicaragua. Models do show that another tropical system could form in the Caribbean or Gulf of Mexico within a week. This tropical cyclone could have a chance at making landfall somewhere along the Gulf Coast by the end of next week, although it’s too far out to say if this will actually happen.

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09.21.10

World Wide Weather #18: Sarh, Chad

Posted in Non-US Weather, Weather News at 4:06 pm by Rebekah

This week’s post in the global weather and climate series features Sarh, Chad (click for a Yahoo! maps link).

Chari River, near Sarh, Chad. From Kejsa Media Network.

This time of year, central African weather is dominated by tropical (aka easterly) waves. Tropical waves are low-level troughs within the tropics, which provide lift for thunderstorms and are a major source for tropical cyclone development.

Sarh, in south central Chad, is currently under a cloud cluster associated with one of these tropical waves. If the tropical wave survives its journey across Africa, it could have a chance at becoming a tropical cyclone in the Atlantic Ocean.

Infrared satellite image over central Africa, showing at least two cloud clusters associated with tropical waves. From Weather Underground. Click to enlarge.

Sarh has a population of 108,061, and is the 3rd largest city in Chad. Located on the Chari River, Sarh is about 30 miles north of the Central African Republic. Sarh, formerly known as Fort Archambault, was founded by the French for returnees from Congo-Ocean Railway labor camps. Today Sarh is a major transport hub and a center for the cotton industry.

A few more facts about Sarh (weather data from World Climate):

  • Time zone: West Africa Time (UTC+1)
  • Elevation: 1,138 feet
  • Climate zone: Tropical savanna
  • Average high temperature: 95 °F (35 °C)
  • Average low temperature: 71 °F (22 °C)
  • Average annual precipitation: 38 inches (969 mm)

Current weather: Sarh is expecting thunderstorms to continue throughout this week and next, as a result of the tropical wave currently over Sarh and the next one coming their way. Highs this week will be in the upper 80s to lower 90s, with lows in the lower 70s and dewpoints in the upper 60s to lower 70s.

For weather maps and information on current and forecast Sarh and Chad weather, see Weather Online UK (maps, models, and forecasts for around the world), and Weather Underground.

For more information on Sarh, here’s a link to Wikipedia.

Next Tuesday I plan to take a look at the climate and weather in another part of the globe.  As always, if you have any comments or suggestions for future cities, please leave a comment on this post!

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09.16.10

Chase #27: Score!

Posted in Storm Chasing at 1:25 am by Rebekah

Long story short, saw one tornado about a mile east of Mulvane, Kansas, on the Sedgwick County supercell.

I was chasing with Jeff Makowski…we didn’t leave Norman until 3:18pm, and watched the supercell blow up on our drive up I35. We saw this particular tornado at 6:52pm, from less than a mile southeast of the tornado. The funnel cloud in these photos was most of the way to the ground, and I do believe I saw some dust briefly kicked up underneath it.

We followed the storm to just northeast of Winfield, where we suddenly got hit by RFD. The CGs were so frequent and so incredibly close. We were driving south, away from the storm, but got hit by blinding rain and had to pull off the road into a driveway.

We decided to wait it out, as we could barely see the road and it was starting to hail. The biggest stone I saw fall was over golfball size…I’d estimate about or just over 2 inches in diameter. At this time we were hearing reports on the radio of rope tornado sightings about 5 NE Winfield and 12 NW Dexter…really close to where we were! (Too rainy and dark for us to see anything.)

The storm passed to our east, and we went on our way home. Here are a few of my photos…more to come later, once I catch up on web chase logs and photos! There was some incredible structure as well, though I have few good photos of it.

This was my first September and fall season tornado! This was also my first tornado in Kansas this year, and the 7th one I’ve seen this year.

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09.14.10

World Wide Weather #17: Naples (Napoli), Italy

Posted in Non-US Weather, Weather News at 3:50 pm by Rebekah

This week’s post in the global weather and climate series features Naples, Italy (click for a Yahoo! maps link).

The Bay of Naples, from the Sant'Elmo Castle. Mount Vesuvius is on the left. Courtesy of Wikipedia. Click to enlarge.

Naples (Napoli in Italian) is one of the oldest cities in the world, founded sometime in the 9th century BC. It is needless to say that Naples has a long, rich European history, as the city has seen several civilizations come and go. Naples is situated on the Bay of Naples, on the southwest Italian coast. The city lies in the shadow of Mount Vesuvius, which famously blew up in 79 AD, burying the city of Pompeii for nearly 1600 years.

A few more facts about Naples (from Wikipedia):

  • Time zone: Central European Time (UTC+1) or Central European Summer Time (UTC+2)
  • Elevation: 0 to 56 feet
  • Climate zone: Mediterranean (mild, wet winters, warm/hot, dry summers)
  • Average high temperature: 69 °F (20 °C)
  • Average low temperature: 51 °F (10 °C)
  • Average annual precipitation: 39.6 inches (1,007 mm)

Naples’ average monthly low and high temperatures range from 39 °F to 85 °F.

Current weather: Southern Italy is currently under weak low pressure, with no big disturbances nearby (see below, from the UK Met Office). The weather is pretty mild, with highs in the upper 70s this week and lows in the lower 60s. Skies are clear, but there is a slight chance for rain tonight. Low pressure systems are staying primarily in northern Europe, with high pressure systems south of Italy, so the weather is expected to remain pleasant.

Italy occasionally gets severe thunderstorms, especially in the fall. ESTOFEX, the European Storm Forecast Experiment (forecasts for severe weather in Europe), has actually predicted a slight risk of severe storms over southern Italy for today and tonight (see below). This severe weather risk is at 5% for severe weather within 40 km (25 miles) of a point. Severe weather is defined as a tornado, hail of up to 2 cm (0.79 in) in diameter, wind speeds of at least 25 m/s (56 mph), or excessive rainfall of 60 mm (2.4 in) in 3 hours or 90 mm (3.5 in) in 6 hours.

The discussion for southern Italy read (emphasis added):

“Areas from Thyrrenian sea southwards into the southern Mediterranean will be affected by the slowly moving upper low. Moderate instability seems to become available, which should support deep convection. Despite the rather limited shear in place, as the mid-level jet slowly weakens, numerous organized storms will form. Multicells and a couple of rotating storms can be possible. Given their rather slow moving nature, they should bring threat for intense rainfalls as well as some marginal hail in the beginning before they cluster. Train-effect of the storms should locally enhance flash floods. Warm SSTs and steep LL lapse rates could also result in a couple of waterspouts.”

The ESTOFEX website can be found here.

For weather maps and information on current and forecast Neapolitan (yes, that’s of Naples) and Italian weather, see Meteo Italia (Italy’s weather service), Weather Online UK (maps, models, and forecast for around the world), and Weather Underground.

For more information on Naples, here’s a link to Wikipedia.

Next Tuesday I plan to take a look at the climate and weather in another part of the globe.  As always, if you have any comments or suggestions for future cities, please leave a comment on this post!

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09.10.10

Chase #26: On The Way To Kansas

Posted in Severe Weather Forecast, Storm Chasing at 11:46 am by Rebekah

Off on another September chase today. Eastern Kansas looks favorable for supercells with large hail and a few tornadoes. CAPE is high, shear is decent, lift is decent, and moisture is high. The low-level winds could be better (i.e., stronger and more backed), but it could turn out to be a good day for storms.

Target is around Emporia, Kansas, with adjustments possible to the east and either north (better shear north of the warm front) or south (possibly better lift near a surface low), as necessary.

SPC has a 5% risk of tornadoes and a 30% chance for large hail in eastern Kansas.

We’re on the road now, going up I-35 in northern Oklahoma. You can follow us at Green Sky Chaser or Spotter Network, and we’ll be streaming with ChaserTV (my ChaserTV page here).

For the latest updates from the road, check out Green Sky Chaser on Twitter.

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