Summer Scorcher

It’s Summer. It’s Phoenix. 99% of the time, you could probably say “it’s ridiculously hot” and you’d be spot on. The Phoenix forecast didn’t disappoint as the LOWEST the temperature got at any point was 85 degrees. Even today, it’s incredibly hot even for Phoenix’s standards, as this morning’s low temperature… the LOW temperature was 94 degrees, which broke the record of 91 set back in 2006. In other words.. just stay inside, it’s stupid hot out there. The Weather Channel brought home the win with their incendiary forecast.

Monday: High 107, Low 85.
Tuesday: High 113, Low 89.
Forecast Grade: B

Path of the Derecho

As Ryan mentioned, we’ve been analyzing the forecast and verification of a system that would affect the Northern Plains over the last couple of days, which was kind of all over the place but eventually honed in on during the morning of the event. The NWS put together a pretty neat graphical overview of the event, as taken from radar images of the storm from start to finish as it went from central North Dakota through northern Minnesota:
NDMNDerecho2014

As you can see, the main corridor of severe wind reports followed the northern portion of the derecho as it marched though North Dakota. The southern end got a bit more intense as it moved through Minnesota, and as you can tell, the atmosphere was very capped over SD and southern MN. The southern end made very little progression to the south, while there was plenty of activity on the northern end even away from the main line of storms. So while the forecast took a couple of days to really nail down, and was fairly elusive in doing so until the day of, the SPC got it pretty much dead on, and the radar images prove it as well.

After all that… not bad

Yesterday, I highlighted the lead up to a potentially significant severe weather outbreak in the Dakotas and Minnesota yesterday. It was a little circuitous, and very clear that there wasn’t much confidence or consistency at the SPC for what was going to happen. In the end though, by Monday morning, they had it pretty close to nailed. The thunderstorms developed over North Dakota and congealed into a strong squall line that moved from near Bismarck to Grand Forks and into northern Minnesota. You can see the verification, with storm reports overlaying the convective outlook.
Verifying
So it took a while, but the forecast eventually ended up pretty close to reality. Of course, I need to remind everyone that we also had this less than 24 hours before the thunderstorms actually erupted:

Next time, I’m sure they will nail something down with a little more lead time.

The crazy evolution of a thunderstorm outlook

There is a moderate risk for severe thunderstorms today from the Dakotas to northern Minnesota. How we got to this point is rather circuitous. Let’s take a look at the past 24 hours of SPC outlooks. I don’t think I’ve seen one of these things change so much pre-storm in a very long time. Here is what we started with yesterday morning:

A slight risk, covering most of Minnesota and a lot of the central Dakotas. Furthermore, they had the best threat for severe storms around the North Dakota/South Dakota and Minnesota tri-state.

After a shift change and perhaps the usage of a hallucinogen, Sunday afternoon’s update gave us this moderate risk, with a center about 150 miles to the east-southeast.

And now, thunderstorms were going to be significantly stronger.

Whoa! 45% and hatched, when we only had 30% earlier. And there isn’t much of an overlap, either.

So obviously, something changed, the onus was now on the Twin Cities, St. Cloud and Rochester to be prepared for — Oh, wait. This was the outlook from the overnight.

So we’re back into North Dakota and northern Minnesota, which, initially, wasn’t even in a slight risk for yesterday’s updates. This time, the center shifted about 175 miles to the northwest. Was the threat for significant weather still high? Why yes, yes it was.

Where are we at now with the morning update, you may ask. Pretty similar to the overnight outlook, actually, but greatly elongated.

The only thing is that the threat for strong winds seems to be sneaking back deeper into Minnesota, practically to Wisconsin.

http://www.spc.noaa.gov/products/outlook/day1probotlk_1300_wind.gif?1405956293553

Actually, that’s a pretty significant change, increasing the coverage of significant severe weather like that. There is also a 5% tornado threat now in North Dakota and northwest Minnesota. that really grew over the course of the past two updates.

Expect the afternoon update to push the focus into Iowa.

Boise, Idaho to Phoenix, Arizona

I’m surprised to find out that our journey from Idaho to Phoenix will only take two days. It seems longer than that. The two towns are 908 miles apart, and in fact, the primary connector is a US highway, so speeds will be limited to 60.5mph, and our first day will only net us 483 miles. This is going to be a fairly barren drive, but what will the weather hold?

DAY ONE (Monday)
Boise
Boy, there isn’t much going on between Boise and Phoenix, is there? Beautiful drive, but make sure you hit the restroom whenever you have a chance. As for significant weather, it should remain confined to the first few hours of the trip. There could be a splash of rain or an isolated thunderstorms around the Sun Valley. I think our best bet, however, will be for showers or storms between Twin Falls, Idaho and Wells, Nevada. Rain is highly unlikely south of Wells, but will be possible from Boise to Twin Falls as well. I wish there was a better place for us to stop, but we’re just going to call it a day in, oh, I don’t know Seaman Range HP? What he heck is an HP? Maybe the Highest point? Just plan on camping off by the side of Nevada 318 in southern Nevada.

DAY TWO (Tuesday)
It’s going to be CRAZY hot driving from southern Nevada to Phoenix. Like, don’t slow down, because your tires will melt to the road if we slow down hot. Sunny skies, a quick trip through Vegas and maybe a cactus at the side of the road, but nothing in terms of climate for our drive on Tuesday. Find some air conditioning though, seriously.
phoenix

Phoenix, Arizona

I almost called it Phoenix, Missouri, which would have been wrong. So much Missouri on the brain.

At 851AM, PT, Phoenix was reporting a temperature of 91 degrees with mostly cloudy skies. Before 9am and with clouds, all with temperatures already in the 90s, today will be a very warm one, and little change is in order going forward.
Thermal low pressure looks to be the most significant feature with monsoonal thunderstorms remaining in the higher terrain. Extra sun will mean even warmer temperatures as the weekend continues.
Tomorrow – Sunny, High 106, Low 81
Tuesday – Even hotter. High 109, Low 82

TWC: Tomorrow – Mostly Sunny High 107, Low 83
Tuesday – Partly Cloudy High 112, Low 84

AW: Tomorrow – Very warm with intervals of clouds and sunshine High 106, Low 84
Tuesday – Partly sunny and hot High 110, Low 85

NWS: Tomorrow – Sunny High 106, Low 82
Tuesday – Partly Sunny High 109, Low 84

WB: Tomorrow – Mostly sunny. HIgh 107, Low 83
Tuesday – Partly cloudy. High 108, Low 85

WN: Tomorrow – Mostly Sunny High 106, Low 82
Tuesday – Partly Cloudy High 109, Low 84

I can’t even imagine that. We have heat advisories here in the Twin Cities and it’s 20 degrees warmer in Phoenix.
Phoenix

Rain steers clear of the Show Me State

Two forecasts in a row in Missouri, both with a shot of rain according to some outlets, but two dry verifications. The anticipation for rain was more universal in Springfield, but it was just as dry there as it was in Columbia. WeatherNation was the only provider that had a dry forecast, but their temperature forecast was subpar. The differentiator was a combination of two things. Those who had a warm forecast on Friday afternoon and those who hedged cooler on Saturday morning ended up earning the top spots. The Weather Channel edged out Victoria WEather and the Weather Service to earn the victory.
Actuals: Friday – High 78, Low 60
Saturday – High 82, Low 57

Grade: B

A sure sign of a cool summer

This is the current hazard map for the Twin Cities NWS office.
Heatwatch

Temperatures are going to warm up for the beginning of next week, and dew points will climb into the 60s, leading to heat indices around 100, leading to an excessive heat watch. Certainly, excessive heat is in the eye of the beholder, much like freeze watches or wind chill advisories. They aren’t going to be issuing these advisories or watches in St. Louis or Dallas, and they don’t continue to issue them if the warning area should have acclimated to a particular temperature by that point in the season. Like, the 3rd day below freezing in a row, the 3rd stretch of 90s in a season, whatever.

So anyways, what I’m trying to say is that these heat indices reflect the fact that Minneapolis is just not used to the 90s, and these warm temperatures this week will be a bizarre aberration –
screwy temp trends

Whoa, wait. Nope! Temperatures in the Upper Midwest will be very close to normal for this time of year. It will even be a bit cooler than normal just east of town. Admittedly, this is the 6-10 day graphic, and will be valid after the temperatures spike on Monday, but if temperatures cool off this dramatically, and we are getting our first advisory in late July, well, it’s been a cool summer in Minneapolis.

Masterful in Missouri

There was some model guidance that insisted upon a weak wave moving through the southern Plains before turning north into the Mid Mississippi Valley on Thursday, but right thinking forecasters recognized that that guidance was nonsense. Half of the forecasters in Columbia called for rain, and were wrong, while the other half, including Accuweather, who missed by a mere 2 degrees on their temperatures, properly foresaw high pressure squashing any convective development and preventing rain showers. As you may have figured, Accuweather’s solid performance and easily won the top spot.
Actuals: Thursday – High 79, Low 54
Friday – High 80, Low 59

Grade: A

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