Storms and Weather » Mid Level

Tornadoes Slight risk for much of the High Plains tomorrow!

Wed, 05 Oct 2011 22:00:14 +0000

Slight risk for much of the High Plains tomorrow!

http://www.tornadovideos.net/images/stories/day2otlk_1730.gif" />Modest moisture return and weak instability will limit a more widespread severe weather event tomorrow afternoon/evening, but all modes of severe weather are expected--including the risk of isolated tornadoes. The photo, left, shows the areas highlighted, in yellow ,by the Storm Prediction Center for tomorrow for the greatest severe weather threat. Current surface observations show mid to upper 50 dewpoints in the Texas Panhandle with lower 60 dew points onshore near the Texas gulf coast. Moisture return will try and make its way up from the gulf, but is rather shallow, and will advect northward as far north as western South Dakota by midday tomorrow.

With the approach of a strong mid-level trough and strong surface heating beneath cool, mid-level temps--this will result in instability of 500-1000 j/kg for much of the highlighted area. This could be enough for the risk for large hail, strong winds and the possibility of a tornado or two. The two areas, I believe, that have the greatest threat for tornadoes are in the southern target (towards dusk) in the Texas Panhandle into southwest Kansas and somewhere in between I-70 and I-80 in Kansas and Nebraska.

The forecasted LCL's (cloud bases) are rather high in the southern target, but a higher elevation, deeper moisture/stronger instability under a strongly-sheared environment could be enough for a tornado or two, possibly just after dark. The more likely area for a daylight tornado, would be in the early stages of storm initiation in western South Dakota/ NW Nebraska with lower LCLs (cloud bases), but given the weak instability/moisture return and backing of the mid-level winds, strong winds and large hail seem more likely. It's a tough forecast for those storm chasing tomorrow, but my current plan is to head west on I-80 and determine tomorrow morning a more defined target.

Stay tuned as numerous storm chasers will be out and about in the slight risk area and will be streaming LIVE video[/url] as things unfold. Friday, will once again bring another chance of severe weather a little further east!

http://www.tornadovideos.net/component/content/article/1-latest-news/1397-slight-risk-for-much-of-the-high-plains-tomorrow
Tags: Dew Points, Dewpoints, High Plains, Mid Level, Nbsp Nbsp Nbsp Nbsp Nbsp, Nebraska Lt, Photo Left, Severe Weather, Southwest Kansas, Storm Initiation, Storm Prediction Center, Strong Winds, Surface Observations, Target, Texas Gulf Coast, Texas Panhandle, Tomorrow Afternoon, Tornado Alley Outbreaks and Severe Weather Worldwide, Tornadoes, Weather Event, Weather Threat

Re: Australian tornado climatology and information / Bulahdelah Tornado Report 1/1/1970

Sat, 11 Jun 2011 01:54:58 +0000

I will add a few things here. From what I understand, the temperature/dew point at Taree was 26/22 at 1200 EST. Taking a surface-based parcel of 26/22 from the surface and lifting to 500 mbar gives a temperature of -4/-5. The 500 mbar temperature on the Williamtown sounding was -13. Therefore, a rough estimate of the surface-based lifted index (LI) would be around -9/-8. Using a surface-based parcel instead of a mixed-layer parcel usually gives an overestimation of the instability. However, given the direction of the lower-level winds in the afternoon and the observation of scud cloud around the time of the Bulahdelah tornado I would think that moisture would have been quite “deep” in the afternoon. Also, if the observation of 26/22 was taken at midday then there may have been some further heating during the afternoon.

Taking a look at the upper wind profiles from Williamtown and Coffs Harbour in the afternoon, a couple of things are quite interesting. At Coffs Harbour, the lower-level winds are extremely strong and turn from NNE to SW. This would give an enlarged hodograph with strong anticlockwise turning favouring left-moving supercells. The only flaw with the Coffs Harbour upper-level wind profile is the relative weakness in the 700 to 500 mbar winds (40 to 45 knots, not much of a flaw really). The wind speed at 500 mbar at Williamtown is very strong at approximately 65 knots. However, the lower-level winds are not as strong as at Coffs Harbour. For example, the 850 mbar wind speed is only 20 knots from the NE (still pretty good in Australian standards). I wonder whether between Coffs Harbour and Williamtown there was a blend between these two upper-level wind profiles giving both strong lower-level and mid-level winds. If so, that would be a near-perfect profile for strong to violent tornadoes given the strong instability and low LCL’s present that day.
Tags: Dew Point, General Weather - all topics not current severe weather., Hodograph, Knots, Mbar, Mid Level, Midday, Nne, Relative Weakness, Rough Estimate, Scud, Sounding, Taree, Tornado Climatology, Tornado Information, Tornado Report, Upper Wind, Violent Tornadoes, Wind Profile, Wind Profiles, Wind Speed

Tornadoes Widespread severe weather likely today!

Mon, 30 May 2011 21:00:17 +0000

Widespread severe weather likely today!

http://www.tornadovideos.net/images/stories/2011/may_2011/20110524_cantonok_16.jpg" width="275" height="155" alt="20110524_cantonok_16" style="float: left; margin: 5px;" />http://www.tornadovideos.net/images/stories/2011/may_2011/5.30.11day1otlk_1630.gif" width="125" height="85" alt="5.30.11day1otlk_1630" style="float: left; margin: 5px;" />http://www.tornadovideos.net/images/stories/2011/may_2011/ruc_255_2011053018_f06_wspd_500_mb.png" />http://www.tornadovideos.net/images/stories/2011/may_2011/ruc_255_2011053018_f06_wspd_10_m_above_ground.png" />Severe thunderstorms capable of strong tornadoes and damaging hail and wind are possible today from parts of the south-central Plains all the way to the Canadian border. A powerful mid-level storm system is currently digging into the southern Rockies, with a large part of its energy being shuttled northeast over Kansas, Nebraska and the eastern Dakotas into western Minnesota. As such, the Storm Prediction Center[/url] has issued a Moderate Risk for these areas. By late this afternoon, several areas of thunderstorms are expected to develop. One area of focus will be central Nebraska into south-central South Dakota, where a secondary low/quasi-triple point feature will result in strong low-level shear in a very unstable environment ahead of a dryline and cold front; explosive supercell thunderstorm development is expected by mid afternoon, but storm mode in this area should eventually grow to be more linear in nature, given less than ideal directional wind shear over time. The second area of interest is the vicinity of the broader surface low to the north of this area, which is dragging a warm front and associated moisture into the Fargo, ND area and western Minnesota. Supercells are likely in this area as well, and storm mode should remain relatively more discrete with the benefit of more favorable directional wind shear. A large number of chasers will be covering this event (live video here[/url]), and as always, residents are urged to remain alert to local media for watches[/url] and warnings, especially with this being Memorial Day when minds may be focused on picnics and BBQs. (A reminder of this season's more recent weater fury is above-left. TVN live streamer Verne Carlson captu... Tags: Canadian Border, Central Nebraska, Dakotas, Img Src, Kansas Nebraska, Mid Level, Moderate Risk, Nbsp Nbsp Nbsp Nbsp Nbsp, Noaa, Severe Thunderstorms, Severe Weather, South Central Plains, Southern Rockies, Span Style, Storm Prediction Center, Storm System, Target, Tornado Alley Outbreaks and Severe Weather Worldwide, Tornadoes, Western Minnesota, Wspd

Re: Tornado near Ballarat – 20th April 2011

Wed, 27 Apr 2011 07:47:40 +0000

From the photos it does appear that the condensation funnel is not reaching the ground (at the time). Since the photos are taken from the top of a hill the funnel may look deceptively low. In any case, I think it's possible that some weak circulation reached the ground for a short period of time. Who knows? If it was the 20th, I do agree that the conditions did not appear favourable for tornadoes. When I first saw this thread I looked at the GFS winds/LI's and was suprised. I was expecting a strong shear/low CAPE environment. As can be seen on the Melbourne sounding, 500 mbar wind speed is only 30 knots. This would be fine in a higher CAPE/warm season storm but in a low CAPE/cool season setup I would typical expect far stronger mid-level winds, say 40+ knots. Lower-level winds are also relatively weak with only 20 and 10 knots at 850 and 900 mbar, respectively. I would be interested to hear John Allens opinions on this funnel/possible tornado. This should be right up his alley. Tags: 20th April, Australian Severe Storms, Weather Events and Storm Chasing, Circulation, Condensation, Funnel, Gfs, John Allens, Knots, Low Cape, Melbourne, Mid Level, Period Of Time, Photos, Short Period, Tornado, Tornadoes, Wind Speed

Tornado near Ballarat – 20th April 2011

Thu, 21 Apr 2011 03:38:28 +0000

I observed a persistant and somewhat organised cell north of Melbourne late yesterday arvo with a consolidated base, multi-directional inflow bands in the low and mid levels, some mid-level striations and the occasional short lived horizontal funnel from the mid-levels, especially in the early stages of development. Took some pics and posted a few here:

http://www.theaustralianweatherforum.com/forum/viewtopic.php?f=23&t=1171

Then this morning I was sent this link to images and report of a tornado near Ballarat:

http://www.thecourier.com.au/news/local/news/general/tornado-sweeps-across-ballarat/2140709.aspx

I note that some of the pics appear to have been photoshopped.

Brad. Tags: 20th April, Amp, Arvo, Australian Severe Storms, Weather Events and Storm Chasing, Consolidated Base, Funnel, Images, Inflow, Local News, Melbourne, Mid Level, Mid Levels, Nbsp, Persistant, Stages Of Development, Striations, Sweeps, Thecourier, Tornado