Monday, July 4, 2016

Heightened Severe And Flooding Threat Tuesday

Past July Weather
We are now halfway through the year - can you believe that? Which *typically* means it's time for the heat to settle in across the region, unlike the lows in the 30s parts of northern Minnesota saw Friday morning. I thought I would take a look at where our typical records are for the seventh month of the year - and while it can be warm, it can also be quite cool this time of year across the region.
First, we'll take a look at record highs. Did you know that only five days during the month of July have never hit 100 over the 100+ years of data there is for the Twin Cities? The "coolest" record highs of the month are on the following days: 2nd (99), 9th (99), 17th (99), 25th (99), and the 29th (98). The warmest record of the month - and the warmest day ever recorded in the Twin Cities - was back on July 14th, 1936, when the mercury hit 108. This was during the stretch of Minnesota's worst heat wave, something we'll talk about more in a minute. Only two of the current record highs for the month of July have occurred since 2000 - both in 2012 - on the 2nd (99) and the 4th (101).
On the cooler side of things, 22 of the current monthly lows are in the 40s - the coolest morning being July 4th of 1972, when the low was 43. None of the current record lows on record were set in the 21st century. The most recent July record low was set back on the 10th of 1996, when the thermometer dropped to 49 in the Twin Cities.
While July holds the warmest day in Twin Cities history, it also holds the wettest day. This year will mark the 29th anniversary of the Twin Cities Superstorm, in which 9.15" of rain fell on July 23rd, 1987, causing major flooding across the Twin Cities. Meanwhile, the easiest record to break is at the end of the month, when 0.79" of rain fell on the 31st of 1911.
80th Anniversary of the 1936 Heat Wave
This week marks the 80th anniversary of the worst heat wave in Minnesota history back in 1936, when highs for a good majority of 1-2 weeks were in the 100s across the region. Many of these records still are in place today, and this heat wave brought the warmest high ever record in the Twin Cities - 108 degrees on July 14th. Not only was the warmest temperature on record at the Twin Cities recorded during this stretch, but at St. Cloud (107 on the 13th which is also tied with two days from 1934), Duluth (106 on the 13th), and Rochester (108 on the 14th) as well. The warmest Minnesota temperature on record was also tied in this heat wave, when it reached 114 on July 6th, 1936 in Moorhead.
Here's a recap of the heat wave from Mark Seeley's WeatherTalk blog: "It started in southern counties on July 4, 1936 with many observers reporting daytime temperatures over 100F. The Heat Wave spread north over the next 12-15 days. Even northern communities reported temperatures close to 100F, and nighttime temperatures remained in the 80s F in many areas, falling into the 70s F near lakes and in low lying areas. There was no respite from the heat, as many citizens chose to sleep outside. It is estimated that this Heat Wave caused over 900 deaths in Minnesota and at least 5000 deaths across the nation. It was also combined with serious drought."
Enhanced Severe Risk - No Such Thing as "Safe Sun"
By Paul Douglas

There were more clouds around yesterday than predicted, otherwise holiday weekend weather was better than most years. Less humidity, fewer raging thunderstorms and washed-out picnics; less running and screaming.
Yesterday's persistent cloud cover got me thinking about 'safe sunshine', which is probably an oxymoron. Unprotected exposure to sun results in aging, sagging and wrinkling of skin. The sun is linked to 2 out of 3 cases of melanoma (skin cancer) in the USA. Over 76,000 new cases of invasive melanoma were diagnosed in 2012; over 9,000 resulting in death, according to the American Cancer Society. Everything in moderation, including sunshine.
Dew points surge into the 70s today. Toss in a high near 90F and it feels like 100F later today with an enhanced risk of severe T-storms. Keep an eye out for angry skies later today.
Skies clear Wednesday before the next round of T-storms Thursday. A drop in humidity Friday sets the stage for another fine weekend with highs near 80F under a partly sunny, pleasant sky.
It would appear we've all won the Weather Lotto this summer.

Extended Forecast for Minneapolis
TUESDAYStrong to severe storms. High 90. Low 70. Chance of precipitation 70%. Wind S 10-20 mph.
WEDNESDAYMore sunshine, a dry sky. High 85. Low 68. Chance of precipitation 10%. Wind NE 5-10 mph.
THURSDAYAnother round of showers, T-storms. High 83. Low 65. Chance of precipitation 60%. Wind SE 10-20 mph.
FRIDAYPartly sunny, turning less humid. High 80. Low 62. Chance of precipitation 20%. Wind NW 8-13 mph.
SATURDAYPlenty of sunshine, quite comfortable. High 80. Low 61. Chance of precipitation 10%. Wind 5-10 mph.
SUNDAYWindier and a bit warmer. High 83. Low 67. Chance of precipitation 20%. Wind SE 10-15 mph.
MONDAYSticky, swarm of T-storms late? High 89. Low 70. Chance of precipitation 50%. Wind 10-20 mph.
This Day in Weather History
July 5th

1999: Flooding occurs over the Arrowhead. The largest 24-hour rainfall total is 8.84 inches in central St. Louis County.
Average Temperatures & Precipitation for Minneapolis
July 5th

Average High: 83F (Record: 100F set in 1982)
Average Low: 64F (Record: 45F set in 1972)
Average Precipitation: 0.13" (Record: 1.62" set in 1994)
Sunrise/Sunset Times for Minneapolis
July 5th

Sunrise: 5:33 AM
Sunset: 9:02 PM
*Length Of Day: 15 hours, 28 minutes and 51 seconds
*Daylight Lost Since Yesterday: ~1 mins & 2 secs
*Next Sunrise That Is Before 6 AM: August 3rd (6:01 AM)
*Next Sunset That Is Before 9 PM: July 11th (8:59 PM)
Tuesday And Beyond Minnesota Weather Outlook
We have had five days so far this summer with a 90 degree high in the Twin Cities - could we make it six Tuesday? Highs will soar into the upper 80s and low 90s across southern Minnesota Tuesday, with the Twin Cities potentially seeing enough warmth to make it to 90. With dewpoints climbing to near 70, it'll feel more like the mid to upper 90s at times. Meanwhile, temperatures will be cooler in parts of northern Minnesota, with places such as Bemidji and International Falls likely not making it out of the 70s.
NAM forecast precipitation and clouds every three hours between 7 AM Tuesday and 7 AM Wednesday.
We'll be watching a cold front drag south across the region Tuesday, with storms popping in the afternoon hours across central and southern Minnesota. These storms could be strong to severe and bring heavy rainfall with them.
This is a snapshot of the NAM at 7 PM Tuesday, showing storms moving into the metro area.

Severe risk Tuesday. Dark green - marginal threat. Yellow - slight threat. Orange - enhanced threat.
There is an Enhanced Threat of severe weather across central and southern Minnesota Tuesday, including places like the Twin Cities, St. Cloud, Mankato and Rochester. We'll be watching for the potential of all modes of severe weather, including large hail, damaging winds, and (especially early on in storm formation during the afternoon) isolated tornadoes.

GFS rainfall forecast through Wednesday morning. Green = 1"+. Image: AerisWeather.
Atmospheric water levels will be high tomorrow with this system (precipitable water values will approach 2") which will mean we will watch the potential for very heavy rain. The GFS model (shown above) shows the potential for at least an inch of rain to fall through Wednesday morning across parts of eastern and southern Minnesota.
The Weather Prediction Center has highlighted an area across central Minnesota (including the Twin Cities) Tuesday where rainfall amounts could exceed flash flood guidance with the incoming storms.

GFS rainfall forecast through Saturday morning. Green = 1"+, yellow = 2"+, orange = 3"+, red = 4"+. Image: AerisWeather.
While we will see the rain move out of the area (for the most part) by Wednesday, we will watch another round move in for Thursday and Friday which could be another severe weather and heavy rain producer across the region. As we get closer we'll be able to pin down timing and location a bit more.
Temperatures will hover around average for much of the next seven days in the Twin Cities. Models continue to hint at a possible warm up heading into late next week, with 90s possible once again.
National Forecast Outlook And Stories
Heavy rain has been the main story over the past few days across the Central Plains. Check out some of these select 72-hour rainfall totals through 7 AM Monday morning - some areas receiving over a half a foot of rain within a short amount of time. Columbia, MO saw 3.58" of rain Sunday, not only shattering the old record of 3.14" set in 1984 but also placing as the fourth wettest July day on record.
Flooding In Southern Indiana Monday Morning (photo: @VandSheriff on Twitter):
NAM forecast precipitation and clouds every three hours between 7 AM Tuesday and 7 AM Wednesday.
Storms will be possible across the Northern Plains Tuesday as a cold front moves through, with storms potentially reaching the Chicago area by Wednesday morning. Elsewhere, some showers are possible in the Northeast, especially in the morning hours, meanwhile scattered showers and storms will be possible throughout the day in the Mid-Atlantic and Southeast.

GFS rainfall forecast through Thursday morning. Green = 1"+, yellow = 2"+, orange = 3"+. Image: AerisWeather.
The heaviest of rain from Monday through Thursday morning will be across parts of the northern Plains with that incoming cold front and in parts of the Mid-Atlantic and Southeast, where rain totals could top 2" in spots.
Political Convention Weather
Mean average high temperature for Cleveland and Philadelphia during the time frame for the upcoming political conventions. Credit:
The Republican and Democratic conventions are coming up later this month in Cleveland and Philadelphia (respectively), and asks the most important question of the political season: who typically sees better weather? Here is a snippet from their section on temperatures: "If you like hot temperatures, then visiting the DNC in Philadelphia is for you. If you like to stay on the cooler side, then stick to the RNC in the CLE.  Philadelphia averages about 4 degrees hotter than Cleveland."
Seven Climate Record Already In 2016
Numerous climate records have already been broken around the world so far this year. The Guardian put together a list of seven climate records already smashed in 2016: "From soaring temperatures in Alaska and India to Arctic sea ice melting and CO2 concentrations rising, this year is smashing records around the world."
Thanks for checking in and have a great Tuesday! Don't forget you can follow me on Twitter (@dkayserwx) or on Facebook (Meteorologist D.J. Kayser)!
-D.J. Kayser

No comments:

Post a Comment