Thursday, July 11, 2013

Humidity and Thunder Potential Builds into the Weekend

Summer breeze
By Paul Douglas

Historically, the hottest weather of the year comes 2-4 weeks after the Summer Solstice. Why the lag? Water takes longer to heat up than land, and the combination of high sun angle and warmer water reaches a peak around the third week of July.
Although no debilitating, headline-grabbing, newscast-leading heat is brewing, I could see a few 90s next week - a steamy reward for surviving one of the most turbulent springs in recent memory.
No radar app to track red blobs on Doppler? A simple AM radio can detect lightning strikes within 150 miles. Occasional static pops: isolated storms. If you hear continuous static on the left end of the AM dial: a line of storms may be brewing. Then again you can always rely on Amish Doppler. A window works ever time.
A surge of hot, steamy air may set off a spirited round of T-storms late Friday Night. Most of Saturday looks dry with enough sun for mid-80s. More instability storms sprout Sunday, especially north/west of the Twin Cities. A heat-pump high pressure bubble expands north next week. The best chance of 90s: Tuesday - Friday. Considering that many of complain about cold fronts 7 months out of the year I'm OK with an authentic hot front.

Todd's Conservation MN Outlook for the Twin Cities and all of Minnesota

FRIDAY: Partly sunny and breezy. Storms developing overnight Winds: S 20+ High: 87

FRIDAY NIGHT: Chance of thunderstorms overnight. Breezy and mild. Low: 69

SATURDAY: Sticky, few T-storms. Winds: S 10-15. High: 87

SUNDAY: More late day/overnight storms, humid. Wake-up: 71. High: 88

MONDAY: Hot sun, still steamy. Wake-up: 70. High: 90

TUESDAY: Partly sunny, steamy. Dew point: 71. Wake-up: 72. High: 92
WEDNESDAY: More sticky sun. Wake-up: 72. High: 92

 Extreme humidity played a major role in severe thunderstorms east of the Mississippi Valley on Wednesday. There were up to a few hundred wind damage reports, many of which came in from the Ohio Valley as a massive line of thunderstorms developed and raced toward the eastern seaboard. Thunderstorms were also found across the nation's midsection, where Chuck Koch snapped these two photos below out of Jonesboro, AR.

Storm Report Map From Wednesday
The storm report map from Wednesday is actually quite interesting... you can actually see where the drier, less humid air mass was behind the cold front that produced all the wind damage reports. Look at how much more stable the air was in the Midwest!

Ohio River Valley Storm Damage
Take a look at some of the more impressive storm pictures from the Ohio Valley where most of the damage was located. From wind damage to flooding, it was a VERY active day!

Major Flooding
Another big concern with the storms on Wednesday was flash flooding! Keep in mind that the ground in these areas was saturated due to heavy rainfall from last week. Thunderstorms are unique in a way that they can take all the moisture in the atmosphere and condense it into one column. If you happen to get under that column of heavy rain, flash flooding can certainly be an issue like it was is Pennsylvania seen from the image below. A couple of things to keep in mind when you look at the image below. First, note how there is turbulence in the water on the right... it appears that the water is moving across the road. Second, note how cars are trying to cross the road, this is a BIG NO NO! Flash flooding can be a serious/life threatening situation. Keep in mind that 2 feet of water can float most cars, if that water is running it can turn your car into a moving boat! Also, 6" of running water could knock you off of your feet.

Pittsburgh, PA
Two rounds of heavy rainfall led to record rains in Pittsburgh, PA on Wednesday. The new daily record ended up being 2.44"

Colorado Flash Flooding
Take a look at the image below... pretty scary huh?!? That's a car floating down the road after being swept up in a flash flood/debris flow from nearby heavy rain over a Waldo Canyon wildfire burn scar!

Heavy Monsoonal Rainfall
There were reports of nearly 1" of rain in less than 1 hour in the Manitou Springs, CO area, which is just west of Colorado Springs.

Waldo Canyon Burn Scar
What made the flash flooding so bad? This heavy rain fell in an area that is recovering from a massive wildfire. The Waldo Canyon burn scar is visible from space. There is no vegetation to help keep the earth rooted in one spot, so heavy rainfall sends walls of mud down hills/mountain sides. Before you know it, there a massive debris flow heading your way... SCARY!

Monsoonal Thunderstorms
Monsoonal thunderstorms are pretty unique to the Southwest in the Summer months when intense heats sets up. This is what a typical satellite and radar map would look like on any given day when monsoonal thunderstorms are in progress during the afternoon/evening. These storms tend to die out after the sun goes down and redevelop the next afternoon/evening when the sun heats up the atmosphere.

Record Rains on Wednesday
Interestingly, thanks to these monsoonal storms, Flagstaff, AZ and Santa Maria, CA saw record rains on Wednesday! Note that it only took 0.01" of rain in Santa Maria, CA to get a daily precipitation record; this is typically the dry season.

Daily Monsoonal Thunderstorm Threats
Monsoonal thunderstorms bring several kinds of daily threats from flash flooding to wildfire potential and dust storms. These are pretty unique and typically last from mid June to the end of September in the Southwest.

More Heat in the West/Central Plains
Another strong ridge of high pressure will bubble out into the Plains over the next several days, which will keep the threat for additional thunderstorms across the Midwest. These thunderstorm will develop on the northern periphery of the intense heat and humidity, which is pretty typical for this time of year. Another thing that we will be watching for is the daily monsoonal thunderstorm risk in the Southwest

5 Day Precipitation Forecast
NOAA's HPC 5 day precipitation forecast shows a few things of interest. Starting in the Southwest, daily monsoonal thunderstorms will help to bring heavy pockets of rain there. Strong to severe thunderstorms across parts of the Midwest over the next several days could help to add up the rainfall amounts through the weekend there. More heavy rain along the Eastern Seaboard will keep an elevated flood threat in place through the next several days!

What's Chantal up to?
Chantal can't seem to make up her mind. Wiggling and wobbling across the Caribbean, other than heavy rain, Chantal has had minimal impacts. There is an indication that Chantal could actually regenerate north of Cuba?!? Stay tuned for more!

Typhoon Soulik
Soulik, on the other hand, is a monster typhoon in the Western Pacific that will be impacting Taiwan through the end of the week.

"Taiwan's Central Weather Bureau issued a land warning Thursday night for Typhoon Soulik, which weakened into a moderate typhoon, cautioning the public to be prepared for heavy rain around the country beginning Friday afternoon. Beginning Friday afternoon, Yilan and New Taipei could see extremely heavy rain, with accumulated rainfall exceeding 350 millimeters in a 24-hour period, the bureau said. Eastern Taiwan could see heavy rain and mountain areas there could expect torrential rain, with accumulated rainfall exceeding 200 mm in 24 hours. The storm was packing sustained winds of 173 kph, with gusts of up to 209 kph." 

Thanks for checking in and have a great weekend ahead!
Don't forget to follow me on Twitter @TNelsonWNTV

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