Current Conditions at Sanborn Field

Friday Night: Mostly cloudy with scattered showers. Low: 42

 

Saturday: Mostly Sunny. High: 60

 

 Saturday Night: Mostly Clear. Low: 41

 

Sunday: Partly Cloudy. High: 55

 Sunday Night: Mostly Cloudy. Low: 37

 

Thanks to IconArchive.com for the icons! 

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Discussion:  

Halloween weekend will begin in a soggy fashion as light showers continue Friday night, which should cease by Saturday morning. The remainder of the weekend will remain dry as a high pressure system moves in from the west; this should be good news for any trick-or-treaters wanting to avoid being soaked. Temperatures will remain crisp with highs reaching the lower-60s on Saturday and lows in the 40s for the majority of the weekend. Winds from the northwest will usher in decreasing overnight temperatures dipping into the upper-30s on Halloween night, so it would be advisable to wear heavier clothing if participating in fall festivities on Sunday.

-Millsap

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Forecasters: Ethridge, Millsap

Date Issued: 10/29/21 10:00AM CST

Technical discussion:  

  The GFS model was used in this forecast because the observed surface temperatures matched the GFS model values, although the NAM plumes had more consensus in this regard. There is a possibility of patchy fog for Friday evening; otherwise, the weekend appears to be relatively inactive.

    The closed low that has been over the Midwest for the past few days will begin to move out of the area overnight Friday. This can be seen in the GFS 250mb map. After the low pushes out of the region, a ridge flows over the Middle Mississippi Valley throughout Saturday. The 250mb map shows meridional flow with northerly winds over Missouri changing to zonal flow on Sunday.

    The 500mb vorticity map tells a similar story. There is quite a bit of circulation over Missouri throughout Friday as the closed low pushes out of the region. There are still some remnants of that circulation leaving the area on Saturday but things become fairly calm as the ridge pushes into the area. 

The circulation over the region corresponds to the large amount of moisture that can be seen on the 700mb map. This will move out Saturday and be replaced by dry air until overnight Sunday when another smaller region of moisture moves into the forecast region. This could be attributed to increasing cloud cover at the beginning of next week.

    The 850mb map shows the results of northerly winds on Friday and Saturday as cool air creeps down from the north. As a longwave trough to the north flattens the aforementioned ridge, CAA will not only result in lower temperatures, but should also insinuate a stable atmosphere. If this holds out, any active weather during this time is unlikely. The CAA was supported using the 12Z model sounding for KCOU, which displayed a backing wind profile.

-Ethridge, Millsap

 

 

Current Conditions at Sanborn Field

Friday: Overcast with showers throughout the day. High: 50

Friday Night: Mostly cloudy with scattered showers. Low: 42

 

Saturday: Mostly Sunny High: 60

 

Saturday Night: Partly Cloudy. Low: 43

 

Sunday: Partly Cloudy. High: 55

 

Thanks to IconArchive.com for the icons! 

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Discussion:  

    The end of the workweek will be soggy as showers continue to slowly pull out of Mid-MO. Expect an overcast and chilly day for Friday with rain beginning to clear up late afternoon. Showers will fully exit the area early overnight and clouds follow by Saturday afternoon. Conditions will be warmer on Saturday under the sun before our next front brings another batch of cool air in. A cold front will move through the area near midnight Saturday; it won't bring any rain but temperatures will suffer a small blow heading into Sunday. Halloween still looks dry and enjoyable this year - just don't forget a jacket with your costume! A potentially frigid pattern is setting up early next week which may bring our first frost of the season!

-Splater

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Forecasters: Splater, Schneringer, Bongard

Date Issued: 10/29/21 10:00AM CST

Technical discussion:  

   A strong, stacked closed low exiting the region and a dry frontal passage present the main challenges for this forecast period. The 06Z run of the GFS was used used in this forecast, due to its slightly better handling of morning temperatures and precipitation amounts compared to the NAM. Model soundings and cross sections were also utilized in the creation of this forecast.

    A closed low at the 250-mb level is positioned over the Missouri Bootheel region into western Kentucky this morning. The associated troughing with this system dives down through Missouri and Arkansas, into northern Louisiana. By 12-15Z Saturday, a slight ridging pattern will have moved over the forecast area, before transitioning into zonal flow throughout the day and into Saturday night. Divergence aloft is relatively non-existent, although a strengthening jet streak centered over the Sioux Falls, SD to Marshall, MN region will begin to spread into the forecast area beginning 15Z Sunday. This jet will continue to strengthen as the weekend closes out.

    The low at 15Z this morning is centered over Southern Tennessee/Northern Alabama at the 500-mb level, and it will drag vorticity through the forecast region until 06Z Saturday. This, combined with areas of abundant moisture Friday afternoon into the evening at the lower levels indicates continuing rain at those times. Flow patterns at this level mirror those present above, as troughing transitions into zonal flow as the weekend progresses.

    Missouri is dominated by high RH values at 700-mb. As low continues to exit to the east, this moisture is tugged along with it, and the region will be mostly dried out by 09Z Saturday. Any significant amounts of vertical velocity associated with the system exits the region by this afternoon as well, further indicating that rain won't continue past Friday night. A shortwave will move through the northern plains Saturday morning, moving southeast as it passes over the forecast area between 06-09Z Sunday.

    The 850-mb level is as moisture rich as the layer above, and a time-height chart of Columbia indicates 100% RH through 0Z Saturday. As is happening aloft, the low tracking farther to the east will serve to dry this level out, altough moderate amounts of moisture will still be present until 03Z Sunday. Moisture associated with the shortwave aloft will track through between 09Z and 15Z Sunday, but the amount won't be significant enough for precipitation.

    A dry surface front will pass through the region Sunday between 06Z-09Z, capping off a relatively calm weekend following a week of active weather.

-Schneringer

 

 

Current Conditions at Sanborn Field

Thursday Night: Clouds with showers. Low: 47

Friday: Showers throughout the day. High: 50

 

Friday Night: Scattered showers. Low: 44

 

Saturday: Clouds in the morning, sunny in the afternoon. High: 59

 

Saturday Night: Clear. Low: 43

 

Thanks to IconArchive.com for the icons! 

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Discussion:  

   Keep your rain jacket or umbrellas handy as showers will continue over the next two days. Thursday night will see temperatures in the upper 40s with overcast conditions. Friday, there is an increased chance of rain in the morning, with a chance for a rumble of thunder. No severe weather is expected. The chance for light showers will slowly decline throughout the day. Overcast conditions will persist as Columbia sees colder temperatures and winds, as a result of the low pressure system moving to the East. Friday night the temperature will fall to the low 40s. Saturday will be the first clear day, with no expected rain, bringing sunshine in the afternoon. Temperatures will rise to upper 50s, allowing for clear conditions.

- Heienickle

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Forecasters: Heienickle, Meyer, Orr

Date Issued: 10/28/21 5:00PM CST

Technical discussion:  

    For this forecast, the 12Z run of the GFS was chosen over the NAM. Although both models showed current conditions well, the GFS had a slight edge over the NAM on the placement of the low pressure system over southeastern Missouri. GFS soundings were used to assess the potential cloud cover and rain chances through the period. To assist in temperatures, both the GEFS and SREF plumes were consulted. 

    A large trough was situated over the eastern United States at the beginning of the forecast period as evident at the 250-mb level. Throughout the week into the weekend the trough slowly shifts to the east as the low pressure system occludes over the Ohio River Valley, keeping the trough overhead until 06Z Sunday before the trough finally moves to the east. 

    High vorticity is associated with this trough as seen at the 500-mb level. Circulation persists over central Missouri until it moves away by 09Z Saturday. Circulations suggest higher chances of rain and cloud cover as its over Missouri. After it leaves the area, little to no vorticity is present for the rest of the forecast period.

    At the 700-mb, high amounts of Relative Humidity is present over Mid-MO through 09Z Saturday, when the low pressure system shifts east during its occlusion. This occlusion is supported by its vertically stacked nature through the various levels of the atmosphere. GFS soundings show a saturated air mass until 09Z Saturday, which suggests periods of rain with cloud cover. After the higher RH moves east, drier air filters in for the rest of the period. 

    Temperatures remain on the cooler side as seen on the 850-mb map, with no areas of cooler or warmer weather in Missouri during the next several days. SREF & GEFS plumes, as well as the GFS soundings, suggest our temperatures hold steady until Saturday. Future forecasters should pay attention to the intrusion of cold air over the northern plains as it makes its way into Missouri.

    At the surface, winds remain out of the northwest throughout the forecast period as the backside of the trough struggles to move out of the Mid-Mississippi River Valley. No signs of advection are present, further suggesting temperatures will remain steady through Saturday. 

-Meyer

 

 

Current Conditions at Sanborn Field

Thursday: Overcast, with periods of scattered rain. High: 50

Thursday Night: Steady downpours of rain. Low: 47

 

Friday: Continuous rain, becoming more scattered after noon. High: 50

 

 

Friday Night:  Mostly cloudy with isolated showers. Low: 44

Saturday: Partly sunny. High: 55

 

Thanks to IconArchive.com for the icons! 

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Discussion:  

     Rain will continue for the end of the week and into the beginning of the weekend in Missouri, as a deep trough rolls straight through the heart of the state. Rain will be scattered for most of the day Thursday as we are stuck closer to the center of the LPS, but will pick up later tonight as we enter the backside of the system's flow. This will keep our overnight rainfall fairly steady, but without any risk of thunderstorms or severe weather. Even as the trough begins to exit Friday, moisture from both our south and north will keep the atmosphere wet, continuing the chance of scattered showers and rain. Once we enter Friday afternoon, the risk of rain will slowly decrease. Our temperatures will have been kept in the high 40s to lower 50s up to this point, but will begin to cool Friday night as the influence of this powerful trough decreases, clearing the sky above. Saturday will likely see the return of at least some sunshine as cloud cover further departs to the east with the direction of the LPS. Temperatures will start to warm back to average in the middle 50s.

-McDonald

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Forecasters: Duff, Mcdonald

Date Issued: 10/28/21 10:00AM CST

Technical discussion:  

    The 06z model run of the GFS was used. It was chosen because of the accuracy of GFS model output statistics in forecasting surface temperatures and dew point temperatures for the early part of the forecast period. The NAM tended to run warmer surface temperatures and dew point temperatures. 

A large upper-level trough and jet streak ahead of the trough can be seen on a 250-mb plot of heights, winds, and divergence. Some upper-level divergence persist throughout thursday morning. By 21z Thursday the trough becomes a closed low pressure system moving east across the southern part of Missouri. As the center becomes closer to Mid-Missouri, the jet streak moves away taking divergence with it. Late Friday a jet streak wrapping around the backside of the low moves through the area bringing some upper-level divergence. The system moves east as the weekend begins and should exit the Mid-Mississippi River Valley in the early hours of Saturday morning. An upper-level ridge approaches behind the system. After 18z Saturday zonal flow will continue into Sunday. 

At 500-mb plots of heights, winds, and vorticity show the low centered over southern Missouri at 12z Thursday. The strong low pressure system will continue to move across the bottom part of the state over the next 48 hours. The low pressure system will bring lots of circulation into the Mid-Mississippi River Valley and higher values of vorticity over Columbia throughout the day on thursday will bring continuous rain. Vorticity becomes spotty starting 12z Friday and will remain until 12z Saturday. The sky will begin to clear and conditions will improve early on Saturday as zonal flow begins. 

At 700-mb a stream of moisture from the Gulf of Mexico out ahead of the low pressure system can be seen on a plot of heights, relative humidity, and vertical velocity. The moisture wraps around the low and pools in Mid-Missouri. Higher values of relative humidity and vertical velocity continue through most of the forecast period, but decrease by 09z Saturday. 

As the trough and the low progress east winds will become more northernly on Thursday. The northernly winds, precipitation, and cloud cover will keep temperatures cooler and seasonable throughout the next few days. Temperatures will stay in the lower 50s for highs on Thursday and Friday. The temperatures will stay seasonable due to a northwest wind and clearing conditions on Saturday with highs in the Mid-50's. 

Future forecasters should pay attention to the exit of the system and the return of zonal flow. 

-Duff

 

 

Current Conditions at Sanborn Field

Wednesday: Overcast. Increasing rain chances throughout the day. High: 59
 

 

Wednesday Night: Widespread showers. Low: 47
 

Thursday: Steady rain. High: 50
 

 

Thursday Night: Scattered showers. Low: 47

 

Friday: Overcast. Rain ending in the morning. High: 50

 

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Discussion: We have reached the time of year where you are going to need to start digging that heavy jacket or coat out of the back of your closet as temperatures will continue to drop and rain chances increase on Mizzou’s campus. Abundant moisture along with a low pressure system are going to bring us rain chances throughout the next few days. Scattered rain is expected to begin on Wednesday afternoon and increase to widespread, steady rain showers by Wednesday night, continuing into Thursday. Rain begins trailing off on Friday and the sky will begin to clear as we head into Halloween weekend. Severe weather is not expected, but there could be a rumble of thunder or two. Rain totals are expected to be around 1.5” throughout Friday afternoon.

 

-Kobielusz

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Forecasters: Kobielusz, Macko, Bongard

Date Issued: 10/27/21 10:00AM CST

Technical discussion:  

This forecast was developed utilizing the 06Z run of the GFS20. The same run of the NAM40 resulted in temperatures several degrees cooler than those that were observed. Additionally, the GFS modeled the low-pressure system in the Central Plains with greater accuracy. 

A deep upper-level trough near the Colorado-Kansas border is evident on the GFS 250-mb map. The strongest region of the upper-level jet is found to the trough's west. However, central Missouri will fall under the influence of the eastern portion of the jet stream by early afternoon on Wednesday. This region of the jet is expected to cross the Illinois border by Thursday. The jet streak initially described as being on the western side of the upper-level trough will start to round the trough as the trough deepens on Thursday. It is expected that this jet streak will amplify further south near the lower Mississippi Valley. Missouri will still fall under this deepened trough until it pushes further east towards the end of the forecast period. Upper-level divergence is also expected over the state during daylight hours on Wednesday before dissipating.

500-mb vorticity maps indicate that vorticity will be prevalent around the middle Mississippi Valley throughout the day on Wednesday into the overnight hours. By daybreak on Thursday, much less spin is anticipated. Vorticity is expected to return over central Missouri by Thursday night and into Friday.

The 700-mb layer, already moist at the beginning of the forecast period, is expected to become further saturated through the end of the week. Relative humidity values are expected to exceed 90% by Wednesday afternoon. This moist status will remain until the end of the day on Friday when the layer may begin to dry out. Positive omega values become prevalent over mid-Missouri after nightfall on Wednesday, but will become much less widespread by sunrise before becoming negligible. 

An extremely well-defined low-level jet is seen on the GFS 850-mb map. The jet, having a strong southerly component, will pull warm, moist air from the gulf into Missouri during the day on Wednesday. This will raise the dewpoint temperatures expected at 850-mb through Friday, indicating that this layer will be moist as well. The LLJ will begin to weaken slightly during the day on Thursday as it continues to track eastward. A well-defined low-pressure system will dominate the weather over Missouri though the end of the week. Due to the center of this low-pressure system being just to the south of Columbia, it will encourage rainfall to persist even after the passage of the cold front on Thursday.

At the surface, cooler temperatures are expected following the passage of the cold front mid-day on Thursday. Precipitation totals from this system are expected to range from 1" up to 1.25". A little over half of this precipitation is expected to fall on Wednesday night before the cold front passes through Columbia later on Thursday.

- Macko

 

Current Conditions at Sanborn Field

Tuesday Night: Developing clouds. Low: 51
 

 

 

Wednesday: Overcast. Increasing rain. High: 59
 

Wednesday Night: Overcast. Moderate showers. Low: 47
 

Thursday: Cloudy. Decreasing rain. High: 50

 

Thursday Night: Cloudy. Light rain. Low: 47

 

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Discussion:  You won't want to forget your umbrella this week! Rain will begin Wednesday and will be heaviest overnight. These showers will begin to taper off on Thursday, and by Thursday night, just light rain remains. Overall, these showers will accumulate to around 1.25" of rainfall. Temperatures will feel more like fall, staying in the high 40s and 50s.

- VanUnnik

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Forecasters: VanUnnik, Watts, Bongard

Date Issued: 10/26/21 5:00PM CST

Technical discussion:  

For this forecast period, the 12Z run of the NAM40 model was used over GFS20. This was the choice despite both models running a couple of degrees warmer and placing the low pressure systems across the CONUS in correct positions. The difference lies in the plumes where the model disagreement with NAM was only slight compared to a much larger discrepancy with GFS. The largest challenge with this forecast was tracking the movement of the low pressure system and how it impacts precipitation totals for the region.

At 250-mb we have meridional flow aloft across the CONUS in a trough-ridge-trough pattern. Overnight the ridge starts to become a trough with divergence aloft over the mid-South going into tonight. While energy will start to increase from a positive trough tilt Wednesday night divergence will exist over us, while areas to the west will reside in the trough axis. Thursday evening we will transition to northerly winds going into the night with a closed upper-level low.

At 500-mb vorticity is coming from the western Kansas border tonight and will reach the Midwest tomorrow evening. A low-pressure system will be coming from Oklahoma City as the ridge over the region will become a trough at midnight Wednesday. A low will be passing to the south Thursday morning going into Thursday night changing southerly winds to northerly winds over mid-Missouri.

The 700-mb level will start to dry tonight with a downstream trough beginning to advect moisture into the region tomorrow morning getting divergence to transition into convergence by tomorrow night at 03Z. As the low pressure system passes to the south of mid-Missouri easterly winds in the low level will back to a northerly flow by Thursday night.

Following the low level jet, we will have warm air advection at 850 mb tonight. Due to that advection, tomorrow afternoon is going to increase moisture along with cloud cover. Again, as the low pressure system passes to the south cold air advection  will take over tomorrow behind the system. Despite this passage the moist profile continues to stick around through Thursday night.

- Watts

  

Current Conditions at Sanborn Field

Tuesday: Sunny. Becoming overcast by late afternoon. High: 60
 

 

Tuesday Night: Overcast. Low: 51
 

 

Wednesday: Isolated showers in the afternoon. High: 57
 

 

Wednesday Night: Rain. Low: 47

 

Thursday: Rain. High: 50

 

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Discussion:  Do October showers bring November flowers? Maybe not, but that doesn't change our chances of rain over the next couple of days. Rainfall is expected to be light and isolated during the day on Wednesday before more widespread precipitation begins Wednesday night into Thursday. Total rainfall accumulations are expected to be just under 1.25". 

- Macko

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Forecasters: Macko

Date Issued: 10/26/21 10:00AM CST

Technical discussion:  

This forecast was developed using GFS instruction. The NAM and the GFS modeled the high-pressure system affecting Missouri quite well. However, the NAM was several degrees below the Tuesday morning low temperature whereas the GFS modeled it with great accuracy.

Winds at 250-mb are negligible before the jetstream enters mid-Missouri on Wednesday with winds of 90 knots. This region of the jetstream will quickly push eastward as a more zonal flow is achieved, leaving central Missouri without jetstream influence on Thursday.

At 500-mb, positive vorticity begins to hug the Missouri-Kansas border during the day on Wednesday before reaching the central portion of the state later that night. This spin is expected to remain over the region throughout the day on Thursday. Its presence will likely influence precipitation and cloud cover experienced throughout this time period.

The 700-mb level is expected to remain mostly dry throughout the daylight hours on Tuesday, although a gradual build in moisture is anticipated. By Tuesday night, significantly more moisture will be present with relative humidity values around 95%. This condition will extend through the end of this forecast period. Vertical velocity becomes prevalent early Wednesday morning and is expected to persist throughout the day. That said, negative omega values vary in magnitude during the day on Wednesday. Vertical velocity is expected to peak in magnitude in the overnight hours on Wednesday. 

Following the passage of the warm front, the 850-mb layer will also become moist on Wednesday. 95% relative humidity is expected in central Missouri later Wednesday night and into Thursday. Due to this, and in combination with the variables mentioned above, the greatest precipitation amounts will likely occur overnight on Wednesday into Thursday.

By early Wednesday morning, PWAT values will be at or above 1 inch. These PWAT values are expected to maintain their significance throughout the end of the forecast period. To further evaluate moisture depth, a GFS sounding was examined for the overnight hours on Wednesday. The dewpoint and temperature curves remain closely bonded all the way up to 300-mb.

- Macko

 

Current Conditions at Sanborn Field

Monday Night: Clouds lingering. Low: 42
 

 

Tuesday: Becoming sunny. High: 60
 

 

Tuesday Night: Becoming overcast. Low: 49
 

 

Wednesday: Overcast. Rain beginning in the afternoon. High: 57

    

 Wednesday Night: Showers. Low: 47

 

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Discussion:  After a very eventful afternoon and evening yesterday, today has definitely been the calm after the storm. Today, with a break from the rain, Mid-Missouri will remain cloudy and dry for the rest of the evening and into the overnight hours. Going into Tuesday, we will climb into the upper '50s and low '60s as the clouds push out of the Mid-Missouri region to the east becoming  sunny. Tuesday evening a warm front will push through the region bringing clouds and lows in the upper '40s for Tuesday night. With an overcast sky to start Wednesday, the chance for more precipitation increases as a cold front pushes through Wednesday evening with highs reaching the mid to upper '50s. This cold front will bring a line of showers pushing into the region with precipitation totals reaching up to 1/2 of an inch. Showers may linger going into Wednesday night with lows in the mid to upper '40s.

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Forecasters: Alexander, Gromada, Gotsch

Date Issued: 10/25/21 05:00PM CST

Technical discussion:  

After a very active weather day on Sunday, more seasonal conditions are re-entering the Mid-Mississippi Valley. The focus of this forecast is the ridge that will be slowing moving over Missouri. For this forecast, we decided to work with a blend of NAM, GFS and HRRR models, primarily using the NAM. We are using this method due to how similarly the NAM and GFS models are performing with initial conditions and using the HRRR to determine cloud coverage over the next 18 hours.

Currently, there is a very pronounced upper-level meridional pattern situated across the northern half of the CONUS. During the day on Monday, the trough that brought severe weather is moving farther eastward dragging in a strong ridge behind it. This ridge will be the governing force for the atmosphere for majority of this forecast period until on Wednesday when a trough, currently over southern California, enters the area.

Tonight, we will see low-level clouds that will keep our low temperature in the low 40s. The clouds are expected to begin to clear after sunrise making tomorrow sunny. As the high pressure system and ridge continue to move into our area from the northeast, winds will become stronger and from the east. During the day Tuesday, winds are expected to be around 10-15mph with the sun warming us up to the upper 50s. 

A warm front begins trans-versing Missouri, bringing warmer temperatures and more moisture Tuesday night. Most of this moisture and warmer air will be coming from the Gulf of Mexico via the LLJ. The moisture and warm air that this fropa brings in will keep the low temperature slightly above 50 for Tuesday night. With this warm fropa, more clouds, and eventually rain, can be expected Tuesday night; the rain is expected to begin after sunrise on Wednesday and continue through Wednesday night. On Wednesday, we can expect to see a low pressure system over Oklahoma and moving east. This low pressure system will bring increased values of vorticity and a cold front. These aspects of the low pressure system will effect Columbia, MO the most in the afternoon and overnight hours of Wednesday. There is also some isolated divergence above southern Missouri and northern Arkansas.

The next shift should pay extra attention to the low temperatures on Tuesday night, do to models non-agreeance, and the passage for the low pressure system on Wednesday for rain totals and timing.

 

 

 

Current Conditions at Sanborn Field

 

Monday: Cloudy, becoming partly cloudy in the late afternoon. High: 54
 

 

Monday Night: Becoming clear. Low: 39
 

 

Tuesday: Sunny. High: 63
 

 

Tuesday Night: Becoming cloudy. Low: 49
 

 

Wednesday: Cloudy. Rain beginning in the afternoon. High: 59

 

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Discussion:  

A fall-like weather pattern has set up over the much of the United States. For mid-Missouri, that means changing weather this week. Clouds will persist into the afternoon Monday, with some possible peaks of sunshine by late afternoon. Northerly winds behind the cold front that passed Sunday evening will keep our temperatures in the mid 50s. Clearing skies overnight Monday into Tuesday will allow temperatures to bottom out in the upper 30s/lower 40s. The sky clears and winds turn out of the south as high pressure builds into the region making for a warmer Tuesday. A strong low pressure system currently making its way onshore off of the Pacific Northwest will bring back clouds and rain for Wednesday. 

- Travis

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Forecasters: Baker, Travis

Date Issued: 10/25/21 10:00 AM CST

Technical discussion:  

Stormy conditions will hold off... but for how long? The main concern for this period is the amplified meridional flow that will bringing another low pressure system our way late Tuesday into early Wednesday. We will have a little bit of clearing Monday and Tuesday, but get ready for some more rain on Wednesday. Both the GFS and NAM had a good handling on the low pressure system that passed over yesterday; however, we went primarily with GFS guidance, as it seemed to handle the upcoming low and temperature forecasting quite well when compared to satellite imagery and Monday mornings observed temperatures.

The amplified meridional flow visible on the GFS 250-hPa highlights a ridge separating two large low pressure systems. The backside of the low pressure system that moved through Sunday night will lead to clearing sky conditions. Winds switch easterly when the ridges moves in Tuesday; however, it is quickly replaced by a low pressure system building off of The Rockies. This low pressure system will bring with it large amounts of divergence as a jet streak moves in ahead of the tough.

The pattern at 500-hPa is quite similar to the 250-hPa map; however, Tuesday vorticity maxima make its way up across the Mexico border from remnants of Hurricane Rick. This combined with strong circulation coming off of the low pressure system from the west Wednesday morning will give way to turbulent motion and spin.

As the ridge moves across our area it gives way to the clearing of the sky; however, the 700-hPa map shows moisture building into the area ahead of the low pressure system. This combined with positive values of Geometric Vertical Velocity highlights upward motion. This is also evident in our 06Z sounding as the temperature and dew point lines show overcast conditions. The spacing between the two lines progressively gets closer together throughout the night as more moisture builds in. This gives way to rain and showers by Wednesday afternoon.

Winds out of the north will keep our temperatures cooler Monday. As the ridge moves through, there is glimpse of northwest winds that fuel the drying of the of cloud layer; however, winds switch back to southerly ahead of the low pressure system. The low level jet at 30-35 kts is coming straight from the gulf, leading to large amounts of moisture and warm air that will supply the low pressure system. This is also evident at the surface due to WAA solenoids.

- Baker

Current Conditions at Sanborn Field

 

 

Friday Night: Partly cloudy. Low: 47

 

Saturday: Mostly cloudy with increasing chance of showers. High: 62

Saturday Night: Mostly cloudy with chance of showers. Low: 57

 

 

Sunday: Cloudy with showers and thunderstorms. High: 75

 

Sunday Night: Cloudy with showers and thunderstorms. Low: 50

 

  

 

Thanks to IconArchive.com for the icons! 

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Discussion:  

Fall festivities may need to go on the back burner this weekend as showers and thunderstorms are on the approach. Temperatures should rise steadily as the weekend progresses as should the chance for showers. A low pressure system is headed this way on Sunday night preceded by developing showers and thunderstorms, with showers expected on Saturday as well. Flooding is a potential concern for Sunday lending unsafe conditions to the roads with around 1.25 inches of rain expected over the weekend. These rainy conditions should begin easing up on Monday.

 -Ethridge, Millsap

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Forecasters: Ethridge, Millsap, Cochran

Date Issued: 10/22/21 5:00 PM CST

Technical discussion:  
 

The 12Z GFS was the model of choice for this weekend's forecast. When both GFS and NAM 300 mb heights were compared to the CONUS water vapor satellite, GFS had a better handling of incoming storms and the corresponding low pressure system in the northwestern US. This was outlined by a more amplified trough in comparison to the NAM heights. In addition, there was greater consensus in the GEFS 2m-temperature ensemble models than in the SREF plumes.

Friday night will begin relatively calm with one of the only features of interest being a portion of the jet stream making its exit out of the Midwest indicated by the 250 mb map. The other notable feature would be the increase in moisture at 700 mb, indicative of an increase in cloud cover during the overnight hours.

The following day presents continually increasing cloud cover with a possibility of showers in the afternoon. The 700 mb moisture projection indicates the humidity from the previous night will linger, but nothing stood out in terms of any signs of major precipitation. The same can be said for Saturday night precipitation-wise, but the temperatures will be showing a steady incline. This is likely due to the WAA indicated by the solenoids on the surface level thickness map as well as the veering wind profile on the 12Z soundings. Increasing temperatures associated with the WAA should make the atmosphere more unstable as time progresses, lending a greater possibility of developing showers.

Sunday will make way for the low pressure system's arrival, bringing with it an increased chance for showers and thunderstorms. The 250 mb map showed an amplified trough in the jet stream, which is correlated to the large amount of divergence aloft. This should continue into the overnight hours and into Monday. The 500 mb level indicated a minor ridge over the forecast area followed by a major uptick in vorticity overnight on Sunday around 03 Z. The 700 mb level shows some consensus in regards to the timing of the circulation with omega values displaying a negative value, indicative of upward lift. With over an inch of precipitation expected for the weekend, this lift will provide the energy needed for such thunderstorms to develop. Aside from the steady increase in temperature over the weekend, there will be no drastic changes in this regard. However, the winds at 850 mb show a noticeable increase in speed on Sunday. The winds should also experience a shift to the northwest on Sunday night. This could mean that a cold front will succeed once the low pressure system has passed.

-Millsap, Ethridge