Local Forecast

Wednesday, May 6, 2015 2:41 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


Low Clouds So Far, Rain to Come

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Yes, That's High (for Minnesota) Humidity You Feel

The moisture has increased to a noticeable level across Minnesota in the past day. High clouds moved in during yesterday afternoon and have thickened a bit overnight (see infrared loop from College of DuPage Satellite and Radar Menu). More importantly, dew points have climbed from the 20's this time yesterday morning (see NWS: Last 72 hours of St. Cloud Observations) to the noticeable 50's across the central and southern portions of Minnesota (see NWS Aviation Center Minnesota map and the green and yellow contours on the UCAR hourly dew point analysis). So far, the increase in moisture hasn't produced much except some widely scattered showers in central Minnesota, since the warm front to our south is quite weak (see NWS HPC Latest North American zoom-in surface map). There may be a few scattered showers through the morning hours.

Note that southern Minnesota and much of Iowa have fog with some very low visibility. South central Minnesota and northern Iowa have a dense fog advisory in effect until 9 AM.

Best Chance for Widespread Rain Thursday into Thursday Night

So, we have quite a bit of moisture now. What we need is some strong lift. The best of the lift is locked up with the trough (dashed line in the Plains from Nebraska to Texas on the NWS HPC Latest North American zoom-in surface map). That system triggered the showers and thunderstorms in eastern Nebraska, Kansas, and Oklahoma earlier in the evening (see NWS Upper Mississippi Valley radar loop). That trough will develop a cold front that will swing through Minnesota late tomorrow afternoon. That will be our best chance for widespread showers and thunderstorms with the potential for half an inch or even an inch of rain. There might be a small threat of some severe weather tomorrow afternoon, but that will depend a lot on whether we see a break between the morning and afternoon storms. Before that, it depends on how much lift the slow-moving warm front can generate as it pushes northward.

Some Scattered Showers Possible Today and Early Evening, Better Chances Late Night

Today, with all of the low clouds around, it will be tough for skies to clear, so I expect highs to hover only in the upper 60's to near 70. There will be more scattered showers and thunderstorms this afternoon as the warm front gets closer, but I think there will be more showers and thunderstorms late tonight into tomorrow as the winds blowing the warm, sticky air over the cooler air near the ground strengthen overnight. Late tonight into tomorrow morning will be our first shot at substantial amounts of rain in spots.

There will be a lot of clouds lingering tomorrow, again keeping highs in the lower 70's. Dew points will climb into the summer-like (for us...Floridians would laugh) 60-degree dew points, so it will feel uncomfortable.

This slow moving weather system will push off to our east by Friday. Look for some lingering rain showers on Thursday night and a slow drying out process on Friday. I'm not quite as optimistic about sunshine on Friday as I was earlier in the week. We might see a few sunny breaks in the afternoon, but that will about do it. Highs will stay in the upper 60's to near 70.

Improvement by the Weekend

It still looks like a good start to the weekend/Mother's Day/fishing opener/SCSU graduation/grading finals party on Saturday. Skies will clear out, the air will be drier and highs will be around 70 after a middle 40's start.

The next storm in this active weather pattern will push through Iowa on Monday. This system will pump warm and moist air over cooler air at the ground, setting the stage for more significant rainfall. If I take the forecast literally, most of the rain may miss us to the south, but it's close enough to put the chance of rain or showers in the forecast Sunday night into Monday. Again, the areas affected by the rain could get quite a bit. If we are close enough to the storm to stay cloudy, temperatures will stay in the 50's on Monday with or without the rain. Still, it's a shaky forecast.

Severe Weather Hot Spots and a Way-Too-Early Tropical Disturbance

The storm to our south will have a chance at producing some severe weather along the trough (soon-to-become dry line) in the High Plains this afternoon with a better chance tomorrow afternoon. Because of the threat of clouds all day in Minnesota, Thursday's severe weather threat doesn't extend into Minnesota right now.

There is an enhanced area of clouds and thunderstorms moving through the Bahamas and well off the Georgia and Florida coasts (see infrared loop from College of DuPage Satellite and Radar Menu). The computer forecasts have been trying to make a low pressure system out there even since a week ago. There is some chance that the storms could organize into a low pressure system in the next day or two. The computer forecasts continue to try and strengthen it into a storm with some tropical characteristics (warm in the center, rather than being caused by a temperature difference between warm and cold air). The National Weather Service's National Hurricane Center has an eye on it, but they don't realize that it is guaranteed to develop after I made fun of the forecast last week.

See Forecast Below

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Wednesday 5/6: Mostly cloudy with areas of fog and some spotty drizzle in the morning. Maybe a scattered shower. Cloudy with a chance of showers and thunderstorms developing in the afternoon. Breezy and more humid. Some storms could contain severe weather. High: between 65 and 70. Winds: SE 10-25 MPH. Chance of measurable rainfall: 30% in the morning, 60% in the afternoon.

Wednesday Night: Warm and increasingly humid. Showers and thunderstorms likely both in the evening and in the early morning hours. Early morning storms could contain large hail. Uncomfortably humid. Low: between 60 and 65. Winds: SE 8-15 MPH. Chance of measurable rainfall: 80%.

Thursday 5/7: Mostly cloudy with periods of showers and thunderstorms. Some severe storms possible. High: between 72 and 77. Winds: S 10-25 MPH with higher gusts in storms, becoming W 10-20 MPH late. Chance of measurable rainfall: 70%.

Thursday Night: Cloudy, breezy, with occasional rain showers. Low: between 45 and 50. Winds: NW 10-25 MPH. Chance of measurable rainfall: 50%.

End of "Reasonable" Forecast Certainty

Friday 5/8: Mostly cloudy and slowly turning less humid. Perhaps some late day sunny breaks. High: between 65 and 70. Winds: N 8-15 MPH. Chance of measurable rainfall: 10%.

Friday Night: Partial clearing, cooler and drier. Low: between 44 and 48. Winds: NE 5-15 MPH. Chance of measurable rainfall: 10%.

Saturday 5/9: Partly sunny and seasonably warm. High: between 68 and 72. Winds: NE 5-15 MPH. Chance of measurable rainfall: 10%.

Saturday Night: Partly clear and seasonably cool. Low: between 44 and 48. Winds: NE 8-15 MPH. Chance of measurable rainfall: 10%.

Sunday 5/10: Partly to mostly cloudy, breezy, and cooler. High: between 55 and 60. Winds: E 8-15 MPH. Chance of measurable rainfall: 10%.

For Entertainment Purposes Only.

Extended: Cloudy with a chance of rain or showers Sunday night into early Monday. Highs in the 50's.

Forecast Confidence (10 - "Know what gas will cost next week, Bob?"; 0 - "Been a victim of road rage lately, Bob?"): 7 Tuesday through Wednesday, 6 Wednesday night through Thursday night, 5 Friday and Saturday, 3 Sunday.

Yesterday's High: 74F; Overnight Low (through 2 AM): 56F
St. Cloud Airport 24-Hour Precipitation: Trace; SCSU Precipitation (Through 3 AM Wednesday): TBA

Normal Temperatures for May 6 - High: 66F; Low: 41F
Next Update: Thursday, May 7, 2015 8:00 AM (or as needed)

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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!

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