Friday, June 19, 2009

Severe Weather Threat - June 19

While yesterday turned out to be another cap bust in Iowa that makes all those out-of-state chasers absolutely hate chasing in Iowa, today will definitely not be the same. Must cooler temperatures just above the surface in the lower levels will provide much less of a capping inversion, and with a must stronger wave in the mid-levels combined with significantly more convergence at the lower levels as well with a cold front moving southeastward. All of this will provide the southeast half of the state to see numerous thunderstorms, many of which may be severe with damaging winds and large hail.

Be sure to pay attention to the latest weather information via TV/Radio as thunderstorms near your area. While the risk of tornadoes is forecasted, it would appear that surface winds quickly turning southwesterly will decrease the low level shear dramatically, thus inhibiting the strong low level shear that was expected to aid in tornadic development.

Thursday, June 18, 2009

Cap Bust??

With 700hPa temperatures in vicinity of the 12C range, the cap over central Iowa is quite strong... And with the ever decreasing convergence along any portion of the state it looks less and less likely that storms will fire before dark. I've decided to slowly work back westward towards home with an eye on the sky/radar if something does try to develop.

For now it appears that the Iowa cap will once again win over another fantastic parameter day in June...

Did manage to meet up with the TWISTEX crew and spend some time chatting with them, and grabbed a few pictures with the TIV2 as they were with the TWISTEX crew today. It was good to see all of them and hope to see you guys again!!

Chasing Live!!

Currently on Highway 18 just east of Cylinder, IA and will likely continue east towards Algona before sitting and waiting for a bit longer. Parameters look amazing, and once the cap is able to go then we should see very explosive development of supercells capable of significant tornadoes and hail.

Be sure to watch the chase live via the spotter network maps, the latest radar update from my laptop, and live video from my dash on the Iowa Chaser Live Chase Page!!

Significant Severe Weather - June 18

The updated SPC Day 1 outlook will continue the moderate risk of severe weather across much of northern Iowa and southern Minnesota. There is a significant risk of damaging winds, very large hail, and tornadoes across the area today. In fact, the updated outlook has increased the probability of tornadoes over northern Iowa and southern Minnesota. The morning thunderstorms will actually help increase the risk of tornadoes this afternoon/evening as the outflow boundary left in its' wake will interact with the warm front to create substantial low level shear. This would appear to once again be a very dangerous and life threatening situation over areas of the plains states today.

I will be chasing today across northwest Iowa, this blog will have the latest updates as I can provide them. As we near the afternoon initiation you may be able to view live video from my vehicle as well as track my location via the Iowa Chaser LIVE Chase Page.

Next update in regards to afternoon chasing and severe weather is expected in the early afternoon hours.

Morning Severe

The SPC has issued a new severe thunderstorm watch for northern Iowa as a line of thunderstorms with a history of large hail and damaging winds is moving across northwest Iowa currently and is expected to remain severe through the morning hours. This watch will be in effect until 11:00 AM and cover the areas shown below:


Morning Bow Echo

Thunderstorms cleared the state during the overnight hours, but not before providing several reports of hail and damaging winds as well as a tornado report in northeastern Iowa during yesterday evening.

Early this morning there is a bow echo that is entering northwest Iowa with the potential for damaging winds in excess of 60 mph. This storm has had a history of damaging wind gusts as well as marginally severe hail. The bow echo is a line of storms extending from near Beresford, SD southwards to near Pender, NE; and is moving east/northeast at 35 mph. A Severe Thunderstorm Watch has been issued for portions of northwest Iowa until 9 am for this line of thunderstorms.

This line of storms does appear to travel towards my location, thus will plan for its' arrival between 8:30 and 9:00 AM with the likelihood of a photogenic shelf cloud.

Wednesday, June 17, 2009

Severe Weather Update #2 - June 17

The weak boundary is responsible for several ongoing tornadic storms over north-central and northeast Iowa as well as southern Minnesota. Currently Chickasaw county has a tornado warned storm that has produced a tornado before within the past hour, and this storm may continue to produce tornadoes as it moves to the southeast. Another, perhaps more dangerous storm, is moving into Mitchell and Howard counties in Iowa. This storm has produced a large and dangerous tornado that is responsible for injuries across Austin, MN and nearby areas. These storms are likely to continue to be tornadic in nature for at least the next hour or two. After which the instability may begin to weaken in those areas and we may see the storms weaken... Persons in those areas should be very aware of the conditions and take shelter if any storms approach.

Additional thunderstorms have fired across northeast Nebraska and into southeast South Dakota. Given environmental conditions ahead of these thunderstorms, they are likely to maintain a severe weather threat into the overnight hours. Areas of west-central and northwest Iowa are likely to see these storms as they have the potential to produce significant severe weather. Additional updates are likely as storms continue to threaten areas of the state.

Severe Weather Update #1 - June 17

Severe and now tornadic thunderstorms are ongoing with the stronger warm front located along the Kansas/Nebraska border. Additional storms are likely as we continue through the afternoon and eventually congeal into more of a cluster or MCS of storms moving into west-central and southwest Iowa.

The other area of concern for severe weather, including tornadoes, will be over northwest/north-central Iowa where a convergent low level boundary associated with a weak low pressure system over South Dakota may trigger thunderstorms this afternoon/evening. Latest analysis indicates this wind shift is becoming very defined with strong instability along and east of the boundary. Effective wind shear values above 40 kts will support supercells when initiation occurs, and likely support tornadic storms through the evening hours.

I plan on chasing any development along this wind shift and weak boundary in northwest Iowa, thus stay tuned for additional updates!

Severe Weather Potential - June 17

The potential is there for significant severe weather across the western half of Iowa this afternoon and into the overnight hours. All modes of severe weather appear possible, including damaging winds, very large hail, and tornadoes. There are two areas of concern for severe weather today, both of which cover western Iowa...

The first and most likely concern will be over much of western Iowa, and likely be during the late evening or overnight hours. This severe weather threat will likely be for damaging winds and large hail, although a risk of tornadoes will exist, a more linear nature of thunderstorms may be expected. These thunderstorms will evolve from central Nebraska this afternoon as they initiate due to a shortwave and frontal system interaction. As the thunderstorms continue to evolve eastward they are likely to congeal into a more linear MCS capable of large hail and damaging winds as they enter into western Iowa.

Another threat for severe weather will exist during the afternoon/evening hours over mainly northwest Iowa, as well as southwest Minnesota. Similar to yesterday afternoon over South Dakota, a weak low pressure system in conjunction with a trough of low pressure and low level convergence may lead to thunderstorm development along a weak wind shift line. With even higher temperatures and dew points this afternoon yielding even higher instability amounts this will come as no surprise to see even stronger supercells off of this setup. These storms will be capable of all modes of severe weather through the evening hours, but similar to yesterday they should begin to weaken after sunset.

Additional updates are likely this afternoon as the severe weather threat evolves, I am watching the potential across northwest Iowa for the tornadic supercells similar to yesterday...

Tuesday, June 16, 2009

Severe Weather Update #1 - June 16

Although severe weather is not immediately affecting any portion of the state, ongoing and developing thunderstorms appear to be moving towards northwest Iowa and may enter the state in the coming hours. The most immediate danger would appear to effect Plymouth and Sioux counties in Iowa over the next two hours. The NWS in Sioux Falls has extended the tornado watch that was in effect for eastern South Dakota to include those counties that are in the direct path of a strong tornadic supercell that has had a history of producing tornadoes, some of which have appeared to be strong, over southeast South Dakota. Currently this tornadic storm is east of Yankton, SD and is moving southeast at 30 mph. This path would likely effect Vermillion, SD and eventually towards Sioux City, IA by approximately 10:30 PM. While the tornadic threat may not continue through this time, it would appear that at least damaging winds and large hail would be an issue for areas of Plymouth and Sioux counties.

Additional updates are possible if this continues on its' track towards northwest Iowa.