Thursday, August 27, 2015 7:20 AM
Prepared by Bob Weisman
Professor of Earth and Atmospheric Sciences
Saint Cloud State University
Earth and Atmospheric Sciences Department
Saint Cloud and Vicinity Forecast
Arizona Storm Gives Us a Glancing Blow
More Clouds, Less Sun, Some Rain(?)
The slow-moving storm that has taken all week to move from Arizona to the Northern Plains touched off a huge blob of thunderstorms in the early morning hours over eastern South Dakota (see infrared loop from College
of DuPage Satellite and Radar Menu). Underneath that blob, there are showers and thunderstorms moving eastward in central South Dakota (see NWS
Upper Mississippi Valley radar loop) . The upper-level steering winds do turn to more northwest-to-southeast over eastern South Dakota and Minnesota (see water vapor loop from College
of DuPage Satellite and Radar Menu), so most of this area will push no closer than southwestern Minnesota. However, we should cloud up for a good chunk of the morning as at least the middle and high clouds move over us. We might see a few morning scattered showers as well.
For the next day and a half, that storm system will drift from South Dakota into Iowa, pumping more warm, sticky air over the cooler air near the ground. This will keep southern Minnesota and Iowa mostly cloudy with showers and thunderstorms likely. Some heavy rainfall is possible. We will be on the northern fringe of the storm. In fact, the trend in forecasts this week has been to track the storm a bit further to the south than earlier in the week. That means the heaviest rain has been pushed further south than earlier in the week. So, we will have a shot at some occasional rain showers. The best chance for those showers will be late today and tonight, but the clouds will continue into tomorrow. You'll notice the increase in humidity as dew points climb into the uncomfortable 60's. The clouds around will limit our high to the lower 70's today and tomorrow.
Warmer (Hot?) Over the Weekend
Once this system pushes out of here, it looks like we will be set up for some of the hot air in the Rockies (high temperatures back into the 90's in parts of Washington and Montana) to try and push into the Northern Plains. Someone threw a bucket of water on the computer forecasts overnight, so they are not calling for middle 90's in Minnesota on the latest runs. Instead, highs well up in the 80's are being shown for most of Minnesota through the weekend and into next week. This could be an overreaction and nudging 90 degrees may be possible, but that will depend on whether there are lingering clouds from overnight showers and thunderstorms. It looks like our best chance of those storms would be Saturday night and maybe Sunday night. However, by early next week, most of those storms would likely be in northern Minnesota or Canada, allowing more sunshine.
So, while we've been dominated by September-like temperatures for much of this week, there's still a good chunk of August weather ahead.
Over the weekend, the high center over the Rockies is expected to drift eastward, allowing more of the heat to drift into the High Plains. At this point, the computer forecasts are showing the potential for highs well up in the 80's on Saturday and well into the 90's on Sunday. However, there will likely be some more weak weather systems spinning around the high from the Desert Southwest into the Northern Plains. That increased amount of clouds will likely temper some of the high temperatures, but I can't figure out which day that would happen. So, I'm just knocking a few degrees off the potential highs to account for it. Still, temperatures should be warmer than we have seen in a week and a half.
Atlantic Hurricane Season Begins to Spin Up
Tropical Storm Erika has just passed Guadeloupe in the northern Windward Islands (see Northern Hemisphere infrared loop from College
of DuPage Satellite and Radar Menu). Top winds are 50 MPH. Tropical storm warnings are out for the Virgin Islands and Puerto Rico since the storm is expected to continue its northwestward track. If that track keeps up, the Bahamas and the Florida coast could feel at least the rain from Erika through the weekend. It is possible that Erika can intensify into a hurricane over the weekend, but that's also a shaky forecast.
There are far more cloud clusters and tropical storms in the Tropical Pacific than in the Atlantic right now (see Hemispheric Products from College
of DuPage Satellite and Radar Menu), including Hurricane Ignacio (winds up to 75 MPH) and Tropical Storm Jimena (winds up to 40 MPH). The higher tropical storm potential is being caused by the unusually warm ocean water over the eastern half of the tropical Pacific. That's the El Nino long range forecasters are blabbering about. If this unusually warm water keeps up through the winter, the Northern Plains would have a good chance of seeing a milder than usual winter. However, any bets on the amount of snow this winter are off.
Confidence Level: "I Will Still Have Dandruff Tomorrow"
Thursday 8/27: Becoming cloudy this morning. Maybe some periods of sun in the afternoon. Breezy, becoming noticeably humid and a shade cooler. A chance of a rain shower. High: between 70 and 75. Winds: SE 8-15 MPH. Chance of measurable rainfall: 30%.
Thursday Night: Cloudy, milder, and more humid. A chance of showers and thunderstorms late at night. Low: between 56 and 62. Winds: SE 5-10 MPH. Chance of measurable rainfall: 40%.
Friday 8/28: Mostly cloudy, breezy, seasonably cool, and noticeably humid. A chance of occasional rain or sprinkles. High: between 70 and 75. Winds: SE 10-20 MPH. Chance of measurable rainfall: 30%.
Friday Night: Partial clearing with light winds and a shade cooler. Areas of fog developing late at night. Low: between 54 and 58. Winds: light SE. Chance of measurable rainfall: 10%.
Saturday 8/28: The return of sunshine. Much warmer and uncomfortably humid. High: between 80 and 85. Winds: SW 8-15 MPH. Chance of measurable rainfall: 10%.
Confidence Level: "The Twins Will Finish Above .500"
Saturday Night: Partly cloudy and warm. A chance of a late night shower. Low: between 62 and 66. Winds: S 8-15 MPH. Chance of measurable rainfall: 30%.
Sunday 8/29: Sunny, breezy, very warm, and uncomfortably humid. High: between 84 and 88. Winds: S 10-20 MPH. Chance of measurable rainfall: 10%.
Sunday Night: Partly cloudy, breezy, warm, and humid. Low: between 62 and 66. Winds: S 8-15 MPH. Chance of measurable rainfall: 20%.
Monday 8/30: Sunny, breezy, very warm, and uncomfortably humid. High: between 84 and 88. Winds: S 10-20 MPH. Chance of measurable rainfall: 10%.
Confidence Level: "The Cat Will Not Sit on My Grading"
Extended: Continued very warm to hot and humid through much of next week??? Highs near 90 on Tuesday??? Better chance of storms???
Forecast Confidence (10 - "Know what gas will
cost next week, Bob?"; 0 - "Been a victim of road rage lately, Bob?"): 8 Wednesday and Wednesday night, 7 Thursday, 5 Thursday night through Saturday, 4 Saturday night and Sunday.
Yesterday's High: 74°F; Overnight Low (through 7 AM): 54°F
St. Cloud Airport 24-Hour Precipitation (through 7 AM Thursday): None; SCSU Precipitation (Through 7 AM Thursday): None
Normal Temperatures for August 27 - High: 77°F;
Next Update: Friday, August 28, 2015 8:00 AM (or as needed)
Ground and Air Travel
Let me know what you think about this forecast and discussion by emailing SCSU
meteorology professor Bob Weisman. Please note that I make the forecast, not the weather!
Are you interested in studying meteorology? If so,
go to the Earth and Atmospheric Sciences Department home page.