Issued at 3:46 PM CDT, Monday, April 30th, 2012
- A few showers early This Evening
- Scattered showers-thunderstorms (severe?) Tuesday/Tuesday Night
- Additional chances for showers mid to late week
-15z SREF significant tornado ingredients index for late Tuesday Afternoon, centered at 7pm. Eastcentral Minnesota could have an isolated spin-up, more details below.
April 2012 had more days in the 50s at Duluth, Minnesota, but fewer days in the 60s and 70s compared to March.
Number of days at or above 50F: 20 in April vs. 14 in March.
Number of days at or above 60F: 4 in April vs. 7 in March.
Number of days at or above 70F: 1 in April vs. 4 in March.
Rainfall report for Sunday Night/Monday Morning, April 29th-30th, 2012
Source: National Weather Service Duluth, Minnesota
Prentice, WI: 0.70″
Butternut, WI: 0.27″
Saxon, WI: 0.20″
4 miles west of Clam Lake, WI: 0.15″
Hayward, WI: 0.09″
Today’s Weather Summary for Northeast Minnesota and Northwest Wisconsin
Skies were partly to mostly cloudy on this final day of April with mild temperatures. Highs were in the 50s and 60s with 40s in Downtown Duluth. Winds were out of the southwest or east at around 10 mph.
Today’s Upper Level Analysis:
500mb flow has transitioned into a more zonal pattern (west to east) A potent disturbance was passing north of our area thru Ontario Province Today with up to 60 meter 12 hour height falls per RUC model analysis. A more impressive system was moving east thru the Pacific Northwest with 60-90 meter 12 hour height falls. 850mb temperatures as of 3pm ranged from +4C in Northeast Minnesota and Northwest Wisconsin to +8C in Southwest Minnesota.
Forecast Discussion for Northeast Minnesota and Northwest Wisconsin
Tonight (April 30th)
The trailing edge of the Ontario disturbance will exit our area This Evening…This feature might be able to pop a shower or two early This Evening, but the majority of our area will be dry. By late Tonight, a S/SW low level jet will start to ramp up ahead of a developing area of low pressure in the Northern Plains. Advection of warmer/more moist air will begin Overnight, and this could lead to scattered showers after 3AM, especially around the Brainerd Lakes region. Lows Tonight will mainly be in the 40s, with some 30s in Northeast Minnesota. Winds will be out of the south or east at around 10 mph.
-Tonight’s low temperature forecast.
-12z 4km Hi-Res NAM forecast. Could be a round of showers/thunderstorms around our area Tuesday Morning thru midday Tuesday.
-12z 4km Hi-Res NAM forecast for Tuesday Evening, additional storms are forecast to develop according to this model. Note: This is just 1 model’s take on how things may play out Tuesday and Tuesday Night.
Tuesday and Tuesday Night (May 1st)
…A few severe thunderstorms possible Tuesday Afternoon and Evening…
An area of low pressure will be passing west-northwest of our immediate area. A warm front is expected to lift north out of Southern Minnesota while a cold front heads east out of Western Minnesota.
-Low level jet of 30-45 knots will be common in Minnesota ahead of this system with 850mb td’s climbing to +8 to +12C.
-Instability will be on the increase with CAPE of around 1000 j/kg by midday Tuesday-late Tuesday Night. Lower amounts of instability is expected in Northeast Minnesota and far Northwest Wisconsin.
-Dewpoints rising into the 50s, maybe even the low 60s in Southern parts of our area.
-Wind shear will be present. Surface winds: S/SE. 850mb winds: S. 500mb winds: W/SW.
-A mid level jet of around 50 knots will push E/NE out of the Northern Plains while an upper level jet with two stronger wind maxes…One north of the border of around 100 knots with an 80 knot wind max moving NE out of the Northern Plains.
The ingredients mentioned above will be enough to produce scattered showers and thunderstorms across our area for Tomorrow and Tomorrow Night. There is some uncertainty, however, in regards to how much sunshine will see on Tuesday and this is important since cloudier skies and more persistent convection would limit heating, resulting in lower instability levels compared to those mentioned above. If this occurs, then the severe threat would be much lower in our area.
If the forecasted CAPE values and moisture are realized, then there would be a risk of severe thunderstorms especially Tuesday Afternoon and Evening.
*0-1 KM EHI of around 2 combined with 1km Helicity of around 150 m2/s2 working with around 40 knots of 6km Bulk Shear and Effective Bulk Shear would be favorable for a few supercells and possibly an isolated tornado risk, especially in Central and Eastern Minnesota between 5-9pm Tuesday.
-The main hazards from storms that become strong to severe would be from hail and gusty winds along with heavy rain and dangerous lightning. Again, an isolated tornado risk is also possible late Tuesday Afternoon-early Tuesday Evening, mainly for Crow Wing, Southern Aitkin and Pine Counties in Northeast Minnesota and Burnett County in Northwest Wisconsin…This tornado risk also extends farther south as well, into Central Minnesota.
High temperatures on Tuesday will be in the 60s and 70s with cooler temperatures near Lake Superior. Lows Tuesday Night will be in the 40s and 50s. Winds during this period will be out of the south, east or west at 10 to 20 mph.
-SPC’s severe weather outlook for Tuesday. All of Northeast Minnesota and Northwest Wisconsin is under a *Slight Risk for Severe Thunderstorms*
-SPC’s severe thunderstorm probability forecast for Tuesday. The majority of our area is in a 15% chance. Higher probs 30% are in Southern Pine County Minnesota, including Pine City. With all of Central, Southern and most of Eastern Minnesota also in a 30% risk area.
12z NAM 1km EHI forecast for late Tuesday Afternoon. Still noticing some higher values supportive of supercell thunderstorm development in parts of Central-Eastern Minnesota.
-Surface map for 7pm Tuesday per HPC. Greatest threat for severe weather, possible supercells will likely be near the warm frontal boundary and area of low pressure along the ND/MN border. Not sure if the warm front will be quite as far north as what this map shows, but will see.
-High temperature forecast for Tuesday.
Extended Forecast, Wednesday-Friday (May 2nd-4th)
The cold front that’ll move through our area Tuesday Night is forecast to stall out in Southern Minnesota and Central Wisconsin while wavering a bit toward the north/south from mid to late week. Scattered showers are possible in our area during this period, but the potential for thunderstorms is lower since will be pretty far north of the actual boundary…The exception to this might be in the Pine City-Shell Lake-Hayward-Park Falls corridor and points south where a few stronger thunderstorms could occur Wednesday and Thursday. High temperatures on Wednesday will be in the 60s and 70s. Highs for Thursday and Friday will be in the 60s and 70s with cooler temperatures near Lake Superior. Lows Wednesday Night and Thursday Night will be in the 40s and 50s.
Long Range Forecast (May 5th-11th)
High pressure will setup to our north while a frontal boundary remains nearly stationary well to our south. A few areas of low pressure will likely eject out of the Western U.S. and move along that boundary. It’s still too early to say for sure how far north the rain will get this weekend into the middle of next week, since the Northland will probably be fighting a dry/stable airmass coming south off that Ontario high. It does look cooler during this period with temperatures near to possibly a bit below average.
-5 day precipitation forecast, valid thru Saturday Morning, May 5th, 2012. (HPC) Some fairly healthy rainfall totals for the Upper Midwest this week. Of course with thunderstorms, some spots will likely receive lots of rain while other locations receive lesser amounts.
5 DAY FORECAST FOR DULUTH/SUPERIOR
.Tonight… Partly to mostly cloudy. Low 40 to 45. Wind east around 10 mph.
.Tuesday… Showers or thunderstorms possible. Considerable cloudiness. High 57 to 62 but in the 40s near Lake Superior. Wind east to southeast at 10 to 20 mph. Chance of rain 40%.
.Tuesday Night… Showers or thunderstorms possible. Mostly cloudy. Low 45 to 50. Wind becoming south to southwest at 5 to 15 mph. Chance of rain 60%.
.Wednesday… Showers possible. Partly sunny. High 70 to 75. Chance of rain 20%.
.Wednesday Night… Partly to mostly cloudy. Showers possible. Low 45 to 50. Chance of rain 20%.
.Thursday… Partly sunny. Showers possible. High 60 to 65. Chance of rain 20%.
.Thursday Night… Partly to mostly cloudy. Low 45 to 50.
.Friday… Partly sunny. Showers possible. High 57 to 62 but cooler near Lake Superior. Chance of rain 20%.
Normal temperatures for Today
Sunrise Tuesday: 5:53 AM CDT
Sunset Tuesday: 8:20 PM CDT
Tuesday’s Pollen Forecast: 8.7/Medium-High