Local Forecast

Friday, September 19, 2014 3:29 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


Occasional Chances for Storms This Morning Through Tomorrow Afternoon

After a couple of days of warm and dry conditions, we are trending towards increased humidity, which means occasional chances for storms the next two days. The best chances will be this morning into midday, this evening until around midnight, and tomorrow midday through the afternoon.

The first wave of warmer air moving over the top of the drier air near the ground is already underway. A storm system on the Saskatchewan-Manitoba border (see NWS HPC Latest North American zoom-in surface map) will strength over the next day or two. In Minnesota, temperatures are in the 50's and even a few 60's early this morning due to the persistent south wind (see UCAR Minnesota surface chart loop) and the stream of clouds from the west (see infrared loop from College of DuPage Satellite and Radar Menu). There aren't that many showers and thunderstorms under this cloud deck (see NWS Upper Mississippi Valley radar loop and Environment Canada Prairie Provinces radar loop). because the moisture underneath the clouds isn't that high...yet. Dew points at the ground are mostly in the 50's with 60's popping up in parts of Nebraska and the Dakotas.

During today, the pumping of warm air over the top of the air we have at the ground will keep that cloud deck mostly over Minnesota. We will have a chance of a few scattered showers and thunderstorms through the morning hours. This afternoon, however, a layer of warm air that has sunk down the east slopes of the Rockies will move over the top of the air trapped near the ground. Earlier, I was hopeful that we could see some sunshine this afternoon, but there is now a chance that lower clouds will hang around all day. The humidity will be up this afternoon as dew points make it into the middle 60's. However, with the lack of sunshine, temperatures will probably stay in the lower 70's. We will also see an increasing southeast wind.

Tonight, the cold front from this storm system will push through Minnesota (see NWS HPC Short-Range forecast map). The best chance of storms will be slightly to the cool side of this front and they will have some trouble developing due to the warm air aloft. So, I expect only some scattered showers and perhaps a thunderstorm during the evening hours. The best chance for storms both early today and this evening will be across the northern third of Minnesota.

Tomorrow, some of the cooler air will work in with a slow drying trend near the ground. However, we will still have to deal with the upper level low, now pushing into British Columbia (see water vapor loop from College of DuPage Satellite and Radar Menu) and its associated pocket of cold air aloft. Since thunderstorms are generated by having a large temperature difference between the ground and the middle atmosphere, we may have a better shot at rainfall tomorrow midday and afternoon than we will have tonight with the cold front. We will begin the day with some sunshine, but loads of clouds will form by late morning. Look for a changeable sky from midday tomorrow through the afternoon with on-and-off rain showers and perhaps a thunderstorm. It will also be quite breezy with highs in the low to middle 70's.

When the sun sets tonight, we'll lose part of the fuel, the heating of the ground, so clouds will break up tomorrow evening. The northwest wind will continue to blow, but temperatures will bottom out in the 40's. Much more pleasant weather is ahead from Sunday through Tuesday. Look for a lot more sunshine (although there will be some afternoon clouds on Sunday). Highs will be in the upper 60's to near 70 on Sunday, then climb back into the 70's both Monday and Tuesday.

Overall, it looks like a warmer general weather pattern for the second half of next week with the main storm track moving well into Canada. Some of the computer forecasts suggest that a storm in the warmer air will drift into the North Central US by Tuesday and Wednesday. If this turns out to be true, our next chance for significant rain after Saturday will be on Wednesday. If that turns out to be true, we could see the warming trend slow down with a lot of clouds and the chance of storms. However, the 7-day forecasts of future storms aren't always that reliable, so I'll hedge on that for now. There may be some potential for highs well up in the 70's or even making a run at 80 later next week. We'll see.

The heavy rains leftover from the eastern Pacific hurricane moved across southern New Mexico yesterday into early today and are headed into west Texas (see radar loop from College of DuPage Satellite and Radar Menu). Over the past 3 days, some parts of southern Arizona and southern New Mexico have seen 3-6 inches of rain. In the deserts, this accounts to one-third to a half of the average rain for the entire year. Some of this rain has fallen in east Texas as well. Today, the heaviest rain will continue to move into Texas. Flood watches continue in the Texas Panhandle.

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Current Watches/Warnings

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Friday 9/19: A chance of a morning shower or thunderstorm, then maybe some afternoon breaks of sun. Breezy and not quite as warm, but becoming uncomfortably humid. High: between 70 and 75. Winds: SW 10-20 MPH. Chance of measurable rainfall: 40%.

Friday Night: Cloudy with a good chance of evening showers and thunderstorms. Warm and sticky. Low: between 58 and 64. Winds: SW 10-20 MPH, becoming W 8-15 MPH after midnight. Chance of measurable rainfall: 50%.

Saturday 9/20: Sunny in the morning, lots of clouds with scattered showers and thunderstorms, breezy, warm but drying out as the day goes on. High: between 72 and 76. Winds: NW 10-20 MPH. Chance of measurable rainfall: 40%.

Saturday Night: Showers ending early, then partial clearing, breezy, and turning less humid. Low: between 47 and 52. Winds: NW 8-15 MPH. Chance of measurable rainfall: 20%.

Sunday 9/21: Some early sun, then lots of clouds mixed with a few sunny breaks the rest of the day. A slight chance of a shower. Cooler. High: between 65 and 70. Winds: NW 10-20 MPH. Chance of measurable rainfall: 20%.

Sunday Night: Mostly clear and cooler. Low: between 40 and 45. Winds: NW 5-10 MPH. Chance of measurable rainfall: 10%.

Monday 9/22: More sunshine, fewer clouds, dry, and warmer. High: between 72 and 76. Winds: SW 5-15 MPH. Chance of measurable rainfall: 10%.

End of "Reasonable" Forecast Certainty

Monday Night: Mostly clear and seasonably cool. Low: between 44 and 48. Winds: light S. Chance of measurable rainfall: 10%.

Tuesday 9/23: Sunny and warmer. High: between 74 and 78. Winds: SE 10-20 MPH. Chance of measurable rainfall: 10%.

For Entertainment Purposes Only.

Tuesday Night: Partly clear, breezy, and milder. A chance of a shower or thunderstorm. Low: between 52 and 56. Winds: SE 8-15 MPH. Chance of measurable rainfall: 30%.

Wednesday 9/24: Mixed clouds and sun with a chance of showers and thunderstorms. High: between 70 and 75. Winds: SE 10-20 MPH. Chance of measurable rainfall: 50%.

Extended: Warm for the second half of next week.

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

Yesterday's High: 75°F; Overnight Low (through 3 AM): 62°F
St. Cloud Airport Rainfall (Since 7 AM Thursday): None; SCSU Rainfall (Since 7 AM Thursday): None

Normal Temperatures for September 19 - High: 69F; Low: 46F
Next Update: Monday, September 22, 2014 8:00 AM
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.

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