Monday, April 15th – Morning Forecast
Monday: Sunny. High: 86°F
Monday Night: Increasing clouds possible isolated storm. Low 65°F
Tuesday: Severe thunderstorms starting in the afternoon, chance for hail. High: 74°F
Tuesday Night: Severe thunderstorms possible. Low: 57°F
Wednesday: : Partly Cloud and windy. High 70°F
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General Discussion:
For our forecast period it is expected that we have severe weather late tonight and into Tuesday evening. Location of these storms will be the biggest challenge to forecasting. These possible storms can lead to strong winds and possible hail for Tuesday night.
Blodgett, Counts
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Forecasters: Blodgett, Counts
Date Issued: 04/08/2024 10:00 AM CST
Technical Discussion:
A blend of the GFS and NAM will be used for the duration of this forecast. To begin at 300mb the sub polar jet has a formed low in Utah and will begin its track over the Great Plains. By 18Z Tuesday this low will be negatively tilted trough. At this time, the right exit region of a jet streak will be moving towards our area conveying that there is convergence at the surface. This low pushes north keeping the greatest risks north of our forecast area.
This low pressure system is vertically stacked throughout our atmosphere so at 500mb there is a similar set up. For overnight hours there is vorticity that is pushing into our area where we could see a isolated storm. Then by 18Z Tuesday this negatively tilted trough and multiple vorticity maxes are in our forecast area. By Wednesday at 09Z this low pressure system will continue north and voriticty max will continue to advect out of the area.
At 700mb it remains dry until 03Z Tuesday and then begins to saturate more by morning at 12Z. With saturation in the higher levels of the atmosphere we could see a higher cloud deck for these storms on Tuesday evening. For 850 mb it becomes more saturated beginning around 15z Monday morning indicating some cloud clover for today. It becomes more saturated throughout the day and indicates the possibility of rain staying more south of forecast area. By Tuesday at 18Z it is fully saturated with a low level jet across the Midwest region. The low being in Nebraska at the time is helping strengthen the low level jet and is why this low level jet is stronger. By Wednesday at 06Z a cold front will pass through our area but there is no severe threat with this cold front.
At the surface it will be dry until Tues 03Z. The NAM and GFS are in disagreement with rain accumulation. Our forecast area could see a trace at this time. The concern of severe thunderstorms doesn’t begin until 18Z Tuesday. From the atmosphere to the surface this is the time that we are seeing a severe thunderstorm set up. Our forecast areas main concern will be hail and isolated severe thunderstorms. In the soundings shear is around 33 knots with veering winds and favorable parameters for convection. With that in mind any storms that develop will have supercell characteristics. The soundings also help visualize the possibility of hail. The soundings show how there is dry air at the mid-levels with strong buoyancy in the hail growth zone (between -10C and -30C). Additionally, the wet bulb temperature crosses the freezing line around 750mb. This allows more evaporative cooling creating more chance for hail growth. After this system moves there will be a cold front cooling our temperatures into mid 70s for Wednesday.
Future forecasters should watch the upcoming low pressure system moving into our forecast area for Thursday that could bring potential for rain.
-Counts