Current Conditions at Sanborn Field
Tuesday: Sunny. High: 62
Tuesday Night: Becoming Partly Cloudy. Low: 51
Wednesday: Cloudy. Rain beginning late afternoon. High: 62
Wednesday Night: Cloudy. Rain. Low: 36
Thursday: Overcast. Rain transitioning to snow by early afternoon. Temperatures falling throughout the day. High: 36
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Get ready for a roller coaster of weather emotions this week. Temperatures for Tuesday and Wednesday will shoot up into the lower 60s. It will be quite breezy overnight Tuesday and into Wednesday, but will still feel pleasant. Do not let this tease of spring's embrace fool you into thinking winter is behind us. A low-pressure system will bring with it the whole nine yards: rain, sleet, and eventually snow. Rain will start Wednesday evening and continue all night into Thursday morning. A cold front will pass through the region before 6am Thursday and our temperatures will take a fast and furious tumble thereafter. As temperatures fall, wintry precipitation will begin mixing in with the rain, eventually transitioning from rain to sleet and eventually snow. It is still too early to pin down exact snow totals as accumulations will depend heavily on how quickly temperatures drop to near freezing.
- Travis
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Forecasters: Cade, Travis
Date Issued: 2/15/2022 10:00AM CST
Technical Discussion:
The biggest question for this forecast period is if and when snow will hit. As rain moves into the area Wednesday evening into early Thursday morning, it appears that the transition from rain to sleet to snow begins late Thursday morning. Snow accumulation totals are still unclear, as it is hard to say for certain what exactly the timing and location of the system will be. Looking at plumes, there is a lot of spread among different models and model runs. GFS appeared to be running better than NAM, but still had quite a bit of uncertainty. The NBM and forecast soundings were also used to aid this forecast.
Taking a look at the NBM, it shows warm temperatures for both Tuesday and Wednesday. It seems to favor 14z as the time when temperatures drop below freezing on Thursday. It also shows the wet bulb temperature moving below freezing at 13z, which for now appears to be when the transition from rain to sleet will start.
Looking at the jet stream at 250 mb, it's looking similar to the last winter storm that moved through early February. The Jet stream sandwiches Midwest on Wednesday before joining just above Missouri Thursday morning. This means the potential for forcing and also moisture transportation is possible to help produce this system. Along with this, divergence moves into the area, alluding to convergence at the surface and lift that would be needed for any potential precipitation.
Speaking of lift, vorticity exists above middle Mississippi river valley Thursday night at the 500-mb level, which is another indicator that some form of precipitation could occur. Before this, Tuesday and Wednesday appear to be quiet.
Looking for moisture at 700 mb, there isn't much to talk about Tuesday and Wednesday. However, Thursday seems to have abundant moisture early in the morning into the afternoon. This further pushes the idea of precipitation Thursday morning. Temperatures begin to drop below freezing at this level around 14z on Thursday, supporting the idea that this is when the transition from rain to sleet/snow could happen.
A 60 kt LLJ forms above central CONUS Wednesday afternoon at 850 mb. This would allow for moisture transport, giving the needed saturation for some kind of precipitation. Temperatures at this level don't appear to move below freezing until Thursday at 15z, which could be when a possible cold front passes through. Timing and positioning of this front is still quite uncertain, but it could be what allows that transition from rain to snow late Thursday morning.
Warm air advection dominates the Midwest Tuesday and Wednesday, giving us spring-like temperatures. However, cold air advection appears to move over Missouri Thursday morning, lowering temperatures. Nomograms show rain moving to freezing rain early Thursday, then at 15 z moving to snow. A wind shift at 15z indicated a cold front moving through but again, timing and positioning is still uncertain.
Soundings don't show much in terms of saturation for Tuesday and Wednesday, but early Thursday morning appears to have a fully saturated atmosphere, but temperatures up to 700 mb are still above freezing. This warm nose sticks around for awhile before temperatures near the surface begin to move below freezing. Again, this transition appears to happen around 14z, with some sleet in between the rain and snow. With near 100 J of cape at the time of transition, some convective winter precipitation is not out of the question.
Future forecasting shifts will need to keep an eye of this system and look for timing and positioning.
-Cade
The biggest question for this forecast period is if and when snow will hit. As rain moves into the area Wednesday evening into early Thursday morning, it appears that the transition from rain to sleet to snow begins late Thursday morning. Snow accumulation totals are still unclear, as it is hard to say for certain what exactly the timing and location of the system will be. Looking at plumes, there is a lot of spread among different models and model runs. GFS appeared to be running better than NAM, but still had quite a bit of uncertainty. The NBM and forecast soundings were also used to aid this forecast.
Taking a look at the NBM, it shows warm temperatures for both Tuesday and Wednesday. It seems to favor 14z as the time when temperatures drop below freezing on Thursday. It also shows the wet bulb temperature moving below freezing at 13z, which for now appears to be when the transition from rain to sleet will start.
Looking at the jet stream at 250 mb, it's looking similar to the last winter storm that moved through early February. The Jet stream sandwiches Midwest on Wednesday before joining just above Missouri Thursday morning. This means the potential for forcing and also moisture transportation is possible to help produce this system. Along with this, divergence moves into the area, alluding to convergence at the surface and lift that would be needed for any potential precipitation.
Speaking of lift, vorticity exists above middle Mississippi river valley Thursday night at the 500-mb level, which is another indicator that some form of precipitation could occur. Before this, Tuesday and Wednesday appear to be quiet.
Looking for moisture at 700 mb, there isn't much to talk about Tuesday and Wednesday. However, Thursday seems to have abundant moisture early in the morning into the afternoon. This further pushes the idea of precipitation Thursday morning. Temperatures begin to drop below freezing at this level around 14z on Thursday, supporting the idea that this is when the transition from rain to sleet/snow could happen.
A 60 kt LLJ forms above central CONUS Wednesday afternoon at 850 mb. This would allow for moisture transport, giving the needed saturation for some kind of precipitation. Temperatures at this level don't appear to move below freezing until Thursday at 15z, which could be when a possible cold front passes through. Timing and positioning of this front is still quite uncertain, but it could be what allows that transition from rain to snow late Thursday morning.
Warm air advection dominates the Midwest Tuesday and Wednesday, giving us spring-like temperatures. However, cold air advection appears to move over Missouri Thursday morning, lowering temperatures. Nomograms show rain moving to freezing rain early Thursday, then at 15 z moving to snow. A wind shift at 15z indicated a cold front moving through but again, timing and positioning is still uncertain.
Soundings don't show much in terms of saturation for Tuesday and Wednesday, but early Thursday morning appears to have a fully saturated atmosphere, but temperatures up to 700 mb are still above freezing. This warm nose sticks around for awhile before temperatures near the surface begin to move below freezing. Again, this transition appears to happen around 14z, with some sleet in between the rain and snow. With near 100 J of cape at the time of transition, some convective winter precipitation is not out of the question.
Future forecasting shifts will need to keep an eye of this system and look for timing and positioning.
-Cade
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