Friday, June 26, 2009

Severe Squall Line

A mature squall line that continues to be capable of damaging winds in excess of 60 mph and the potential for quarter sized hail is moving swiftly to the east across South Dakota and northeast Nebraska. Current warnings cover the entire length of this line from DeSmet, SD to Pierce, NE...

Along its' current track the line would likely enter southwest Minnesota and northwest Iowa just after 1 AM this morning. Northwest Iowa is most likely to see any damaging winds from this squall line as it enters the state. Those in northwest Iowa should monitor conditions with their weather radio as damaging winds can often cause trees to fall which can produce damage to homes, especially upper levels.

My current plan will be to grab a few hours rest before getting up and heading out ahead of this squall line if it is still in tact as it nears Dickinson/Clay counties. More than likely I will attempt some lightning photography as it nears...

Wednesday, June 24, 2009

Severe Weather Potential - June 24

Quick update from the road today as I am returning from a trip to Ames to visit a few friends. Thunderstorms were widespread yesterday as they continued to move in from NE/SD during the early afternoon hours. Although a few tornado warnings were issued, these tornado warnings were for small vorticies that were confined within the larger line of storms as it moved across the state. No reports were confirmed of a tornado in the state yesterday, but wind damage was widespread through nearly the entire state with wind gusts nearing 80 mph in a few of the stronger storms during the afternoon.

Today's severe weather threat would appear to exist during mainly the late evening and overnight hours as storms once again move out of SD/NE and into western Iowa. A few rogue thunderstorms may develop in localized areas of convergence this evening and have the potential for damaging winds, hail and an isolated tornado. Otherwise it is likely that an MCS will form over eastern SD and continue east/southeast into northwestern Iowa during the early overnight hours. This MCS will likely contain damaging winds and perhaps some small hail as it moves across the state.

Tuesday, June 23, 2009

Welcome Summer...

Apparently summer did not want to show up until it was officially ready, with Sunday being the first day of summer the state sure has heated up since. High temperatures yesterday ranged from the lower to mid 90s across the entire state, with plenty of moisture across a majority of the state to make it feel like temperatures were close to triple digits. Today will be similar, with highs actually getting a few degrees higher than yesterday in most locations. With high continuing in the lower to mid 90s, and even more moisture present today, heat indices will range across the lower 100s. This has prompted a majority of the state to be put under a heat advisory for this afternoons' heat.

Thunderstorms are a possibility across the state tonight and tomorrow, with a chance of a few storms even being near or above severe limits overnight tonight across western and central Iowa. These thunderstorms should be fairly isolated in nature, with marginal hail and damaging winds as the main threats. Temperatures will cool some on Wednesday with the passing of this system, but temperatures should still remain in the 80s across the state. Those temperatures in the 80s should continue through the remainder of the week, with continued high moisture leading to the warm/sticky days and enjoyable nights.

Sunday, June 21, 2009

Severe Weather Potential - June 21

More of a summer-like pattern has pushed into the central plains, with a weak ridge trying to work into the plains states. This has left us with southwest flow aloft through the state of Iowa, and with a low pressure system working off of the high plains and into Nebraska this morning will set us up for a round of severe weather this afternoon. This low pressure system should work into the four corners area of NE/SD/IA/MN by mid-afternoon, with a well defined warm front to its' east/southeast and a trough of lower pressure to its' south/southwest. Along and south of the warm front should have clear skies through the afternoon, with strong heating near 90 and dew points surging into the lower 70s across the area. This should provide us with moderate to strong instability across the state, and with little in the way of inhibition it would likely to see storm initiation fairly early in the afternoon in areas that clear and develop this instability.

Given decent southeasterly flow within the warm sector, low level shear should be sufficient to warrant a tornadic risk. Combined with the very low LCL levels thanks to good heating and moisture present, this tornadic risk seems to be fairly significant. Storms that do develop and move east/southeast nearly parallel to the warm front would have favorable conditions to be tornadic. Thus, would expect areas of northern Iowa, and eastern Iowa where the warm front is more southeast oriented to see the greatest risk of severe weather including tornadoes.

It is Father's Day, thus a lot of people likely enjoying the day outside. It will be important to pay attention to the weather this afternoon due to the risk of severe weather, specifically tornadoes. An additional update near Noon is expected, this will be a brief update in regards to any change in potential.

Friday, June 19, 2009

Iowa Upsets Chasers

Once again the state of Iowa has upset the chasing community with its' lack of cooperation over the past two days. Two straight days of moderate risk, and two straight days of utter disappointment for any storm chaser that was in the state. Both setups featured their own caveats, and both featured the opportunities for greatness, but both days have their caveats win out with no tornado reports and perhaps the highlight of a shelf cloud and some impressive winds this afternoon in southeast Iowa.

Thursday's setup featured a warm front which pushed well north of the state, leaving the state under a heavy capping inhibition between 850 hPa and 700 hPa. With no warm front to help trigger thunderstorms, only a weak remnant outflow boundary had an opportunity for greatness. Although it tried with several cumulus fields attempting to bubble up through the capping inversion, none would ever succeed. Thus, tack a point up for capping inversions with 12C temperatures at 700 hPa over Iowa as a bad chase day.

Today's (Friday) setup finally featured a strong trigger for convection as a cold front moved through the state, and an outflow boundary once again was expected to allow low level winds to remain southeasterly and aid in low level shear. The disappointment would come with winds remaining southwesterly ahead of the cold front, and the lack of a capping inversion allowing the whole cold front to be socked in with showers/storms from Noon onward. At least there were thunderstorms, albeit outflow dominant, that would let you chase something! Wind reports were consistent with at least three separate thunderstorms today, with winds ranging from 60-85 mph across eastern Iowa. Still, a day that would have offered tornado potential for the state would be ruined by a cold front with little inhibition and the lack of cooperation of the surface winds.

If anything can be learned from the past two days, trust instincts that a 12-13C temperature at 700hPa and no strong convergence in the lower levels will lead to nothing but struggling cumulus or blue skies. And, when a cold front comes into the state then you need the 12C temperature at 700hPa along with some southeast if not at least south winds to provide low level shear.

Here's to the hope that the more summer-like thunderstorms can provide some punch for the state with at least some great lightning and supercellular structure!!

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: