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4th of July Outlook and More on the Yarnell Hill Fire Tragedy

Tuesday, July 2nd, 2013

4th of July is fast approaching and weather this year may play a big part in your 4th festivities, especially in the Southeastern corner of the nation. Check the forecast below…

The image below suggests 6hour accumulated precipitation forecast across the country from 1pm to 7pm Thursday, July 4th. Note the heaviest and best precipitation chances look to be setting up in the southeastern corner of the nation with spotty (monsoonal) thunderstorms in the West.

Jet Stream: All Out of Whack

Take a look at the image below. The white line represents the jet stream or strong upper level winds. Note how wiggly it looks as it moves west to east across North America. The reason for our slow moving (stuck) weather pattern is because of this very feature. There is really anything to whisk the dome of hot air or the soggy weather away from their current position. This weather pattern is representative of a “High Amplitude” weather patter and one that tends to last for days.

Highs Today

The jet stream is also the dividing line between the cooler, drier air to the north and the warmer, more humid air to the south. It’s interesting how you can see the temperature contours bubbling north and dipping south with the jet stream.

4th of July – High Amplitude Weakens

The extended forecast finally starts to show the high amplitude weather pattern breaking down a bit by the end of the week. The image below shows the jet stream on Thursday, where the ridge in the west and the trough in the central/eastern part of the country are still visible, but not quite as pronounced as they were earlier this week.

High Temps on July 4th

As the high amplitude weather pattern begins to break down, the heat will begin to subside a touch and shift out into the Plains just a bit. Note that since the stubborn upper level low is still going to be in place over the middle part of the country, there still will be some slightly cooler than average readings there.

More on the Yarnell Hill Fire Devastation

My heart goes out to the families of the firefighters who lost their lives this weekend in the Yarnell Hill blaze. It appears that monsoonal thunderstorm outflow winds helped to bring the fire to uncontrollable levels (interestingly started by lightning). Take a look at the animation below; watch where the fire is located (red circle) and watch as thunderstorms develop northeast of the fires location. As the storm moves in, gusty outflow winds from the storm made the fire explode! You can actually see pyrocumulus clouds (smoke plumes) erupting through the top of the thunderstorms and is slides southwest. Scary!

See the animation HERE

The Yarnell Hill Fire was a relatively small wildfire that was started by lightning from a dry thunderstorm southwest of Prescott, Arizona on 28 June 2013. However, fire conditions became more favorable for growth on 30 June, as surface air  temperatures rose above 100 F across the area with low relative humidity values. During the afternoon hours, GOES-15 0.63 µm visible channel images (above; click image to play animation) showed that a line of thunderstorms developed over northwestern Arizona, and moved toward the southwest (the red circle highlights the general area of the Yarnell fire). It is likely that strong surface winds associated with a thunderstorm outflow boundary (nearby surface mesonet data) caused rapid growth and an abrupt change in direction of the fire, which tragically killed 19 firefighters who attempted to shelter in place (for additional details, see the Wildfire Today site).

On the GOES-15 visible imagery, a smoke plume could be seen after 16:45 UTC, with the first formation of pyrocumulus clouds evident at 21:00 and 21:30 UTC. As the cloud shield of the thunderstorm line moved over the fire, the images revealed the development of a pyrocumulonimbus (pyroCb) cloud (which exhibited a pronounced overshooting top at 23:45 UTC).”

See more from CIMSS HERE:

“Granite Mountain Hotshots”

Here’s a great writeup from on who the Granite Mountain Hotshots were…

Gusty, hot winds blew an Arizona blaze out of control Sunday in a forest northwest of Phoenix, overtaking and killing 19 members of an elite fire crew in the deadliest wildfire involving firefighters in the U.S. for at least 40 years – and the worst since the terrorist attacks on the World Trade Center on 9/11/2001.

The firefighters were members of a “hotshot” crew – the ‘Granite Mountain Hotshots’, tasked with digging a firebreak and creating an escape route. ”A hotshot crew are the elite firefighters,” state forestry spokesman Art Morrison said. “They’re usually a 20-person crew, and they’re the ones who actually go in and dig the fire line, cut the brush to make a fuel break. And so they would be as close to the fire as they felt they safely could.”

“In normal circumstances, when you’re digging fire line, you make sure you have a good escape route, and you have a safety zone set up,” Morrison said. “Evidently, their safety zone wasn’t big enough, and the fire just overtook them.”

Smokey Sunsets?

There are several wildfires burning across North America, several of those fires are in Canada and are creating hazy skies in the U.S.! Take a look at the smoke analysis map below, this is where strong upper level winds have carried smoke plumes and are creating smokey sunrises/sunsets.

See the analyzed smokes plumes HERE:

Thanks to WNTV’s Bryan Karrick for the picture below, who snapped this smokey sunset picture from the Twin Cities on Monday evening! Gorgeous!!

Thanks for checking in, have a great rest of your week!

Don’t forget to follow me on Twitter @TNelsonWNTV

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