Current Conditions at Sanborn Field

Wednesday: Overcast. Rain beginning early afternoon building into the evening. High: 71

 

Wednesday Night: Chance of isolated thunderstorms before midnight. Low: 63

 

 

Thursday: Mostly cloudy with morning fog. High: 73

 

Thursday Night: Mostly cloudy. Low: 65

 

Friday: Sky clearing mid-morning. High: 79

 

 

 

 

Thanks to IconArchive.com for the icons! 

====================================================================

Discussion: 

    Better keep that umbrella handy--today brings our best chance of rain, with accumulations being just under a 1/4". Going into tonight, don't be surprised if you hear a rumble of thunder or two, as we are expecting some isolated thunderstorms this evening. These should clear out by midnight. For the remainder of the forecast period, we will remain dry and cloudy before the sky begins to clear Friday morning. Friday will also bring us some warmer temperatures as we head into homecoming weekend.

- Kobielusz, Macko

====================================================================

Forecasters: Kobielusz, Macko, Bongard

Date Issued: 10/6/21  10:00 AM CST

Technical discussion:  

       The 06Z run of the NAM40 was used to create this forecast. Both the GFS and the NAM accurately depicted current conditions, but the NAM has been repeatedly selected as the model to help forecast the activity of this system. Soundings for Columbia were also utilized in rain, thunderstorm, and fog potential.

    The 250-mb plot is dominated by an upper-level low pressure system near the Missouri-Arkansas border. Throughout the day on Wednesday, this LPS is expected to continue to push north into mid-Missouri. Upper-level divergence was detected for the early evening hours, adding to the possibility of thunderstorm development. By midnight, Columbia will be under the center of the low before moving northeast on Thursday. The jetstream off to our west will cross the Missouri-Kansas border overnight on Thursday before making it to Columbia during daylight hours Friday.

    The NAM40 500-mb plot indicates increasing vorticity throughout the day today. Maximum vorticity is anticipated just before midnight tonight, further encouraging thunderstorm activity. Vorticity begins to weaken during the night on Wednesday before dissipating on Thursday.

    There is significant moisture at the 700-mb level throughout Wednesday with relative humidity values exceeding 95% due to southerly winds, leading us to believe that it will not only be cloudy but also that precipitation is likely today. The relative humidity values will decrease slightly throughout the night. The change in humidity overnight into Friday is much more significant as the atmosphere turns even drier, reducing the amount of cloud cover we will see on Friday.

    Less moisture is evident at 850-mb today, although the layer is still moist (RH ~ 75-85%). The layer will gradually dry out through Friday. The winds at this level are also rather calm, reaching a maximum speed of about 20 knots today. As it concerns advection, the NAM40 showed that there would be a mix of both WAA and CAA over Columbia throughout the day today. However, neither seemed to be of great significance.

   At the surface, we consulted soundings to assess our chances for thunderstorms and potential fog development. The CAPE values found in these soundings were less than those seen using the NAM40 yesterday. Due to the decreased convective potential, it is unlikely that any of the thunderstorms we will see this evening will be strong or severe. However, K-values have remained relatively consistent in the lower 30s, suggesting that isolated downpours may be associated with the showers and thunderstorms today. Upon analysis of a sounding for 12Z tomorrow, temperatures and dewpoint temperatures overlap along with calm winds leads us to believe that there is a potential for fog.

   

- Kobielusz, Macko

Current Conditions at Sanborn Field

Tuesday Night: Mostly cloudy. Low: 61

 

Wednesday: Overcast. Rain beginning late morning. Thunderstorms likely throughout the afternoon and evening. High: 71

 

Wednesday Night: Cloudy. Rain ending after midnight. Low: 61

 

Thursday: Mostly cloudy. Foggy in the morning. High: 73

 

Thursday Night: Partly cloudy in the early evening. Sky clearing after midnight. Low: 60

 

 

 

 

Thanks to IconArchive.com for the icons! 

====================================================================

Discussion: 

    Throughout the forecast period, cloudiness will help keep high temperatures around the lower 70s. This is cooler than the past few weeks, though still above average for this time of year. Tuesday night will be calm, but mostly cloudy. Clouds increase Wednesday, due to the approaching low pressure system. Rain will start late Wednesday morning, so be sure to bring an umbrella, because thunderstorms will start by afternoon and will continue into the evening. These storms will end around midnight, leading to fog early Thursday morning. Cloud cover persists throughout the day Thursday, but sky conditions will begin to clear after midnight.


- VanUnnik, Watts

====================================================================

Forecasters: VanUnnik, Watts, Orr

Date Issued: 10/5/21  06:00 PM CST

Technical discussion:  

       The 12Z run of the NAM was used to create this forecast due to its more accurate initial conditions and more accurate placement of the low pressure system over Louisiana. SREF and GEFS plumes were used to aid in forecasting temperatures, and NAM soundings were consulted for rainfall timing and thunderstorm potential. 

    At 250-mb, plots of heights, winds, and divergence depict a large low pressure system over the Lower Mississippi Valley. Flow over Missouri is dominated by the system for almost the entirety of the forecast period. The low moves over Mid-Missouri around 15Z Thursday, and flow soon falls under the influence of an upper-level jet. There is little divergence associated with the passage of the low, and the most abundant amounts are seen Wednesday around 20Z.

    500-mb plots of heights and vorticity depict the incoming low pressure system's dominance over Missouri's weather over the next few days. The low advects high amounts of vorticity into the region as early as 08Z Wednesday. The abundant vorticity will remain in Mid-Missouri until the low exits the region around 00Z Friday. A ridge begins entering Missouri at this time, and future forecasters should watch for its impact on the forecast area. 

      Plots of heights, winds, and relative humidity at 700-mb show the low pressure system funneling abundant moisture into Missouri. Winds associated with the low will bring in moisture from the Gulf, placing Missouri under high RH values from around 11Z Wednesday to 06Z Thursday. PW values favor Wednesday's rainfall amounts ranging from around 1" to 1.5". Moisture moves out of the region along with the low around 00Z Friday, leading to clearer sky conditions Thursday night. 

    At 850-mb, plots of heights, winds, and temperatures favor slightly above average temperatures for this time of year. Winds begin in a northeasterly direction, but are shifted to westerly due to the passage of the low around 00Z Friday. The shifting winds not only lead to Thursday's higher high, but they also cut off moisture flow from the low pressure system, leading to Thursday's clearing conditions. 

    At the surface level, plots of winds, MSLP, and thickness show the deepening and development of the low pressure system as it passes through Missouri. At this level, the low isn't as defined as it is at upper levels until around 00Z Wednesday. The low continues to mature as it makes its way over Missouri, becoming much more defined by the time it exits the forecast region. 

    NAM soundings were consulted to assess potential for thunderstorms since abundant vorticity and high RH values coincide Wednesday and into late Wednesday night. Thunderstorms are favored to begin around 18Z Wednesday, negative Omega values, LI values of up to -6, and MUCAPE over 1800 J/kg lasting until 03Z Thursday. SRH values in the SFC-1km region are also favorable for thunderstorm development. 

-Orr

 

 

Current Conditions at Sanborn Field

 

Tuesday: Partly cloudy. High: 74

Tuesday Night: Cloudy. Low: 62

 

Wednesday: Showers likely with the possibility of thunderstorms later. High: 69

Wednesday Night: Cloudy. Low: 61

Thursday: Clearing sky. High: 71

 

 

 

 

Thanks to IconArchive.com for the icons! 

====================================================================

Discussion:  

The sun must have requested the day off tomorrow as clouds and the chance for rain tomorrow are the overarching themes of this forecast. Temperatures will cool down slightly after today, dipping a few degrees cooler into the upper-60s by tomorrow. Make sure to bring an umbrella tomorrow as we will see the best chance of rain for this forecast period, with the greatest chances of rain being between mid-morning and mid-afternoon. The possibility of thunderstorms will increase as we head into the afternoon hours before we experience a calm and cloudy night. Total rain accumulations are expected to range from 1/2" to 3/4". By Thursday, we will dry considerably and will get to see the sun once again. 

 

- Macko

====================================================================

Forecasters: Macko

Date Issued: 10/5/21  10:00 AM CST

Technical discussion:  

This forecast was produced utilizing the NAM40 06Z run from October 5th, 2021. The NAM performed better compared to the GFS when modelling current conditions, with the NAM being only a degree cooler than the measured temperature at Sanborn Field. The GFS, on the other hand, was several degrees too cool. Overall, the NAM has been the most accurate when it comes to the weather system impacting us, and has been used in multiple prior forecasts as well.

At 250-mb, there is an moderate upper-level jet stream rounding a trough just to the south of Missouri. A portion of this jet stream covers areas of Missouri, including Columbia, and remains as such until late Wednesday afternoon. The upper-level trough initially south of Missouri will begin to push north overnight tonight, an indicator of the active weather we will see as soon as tomorrow morning. A much stronger jet stream is located off to our west and is expected to reach eastern Kansas late Thursday.

The NAM 500-mb indicates a slight to moderate amount of positive vorticity over the Columbia area today. The strongest vorticity will move in from the southeast tomorrow, implying that some thunderstorm development will be possible. By late Thursday, vorticity will dissipate.

The 700-mb model suggests that humidity will vary from 50% to 75% RH throughout the day today, with these values dropping even lower in the overnight hours tonight. By tomorrow morning, significant moisture is brought into the area via southerly flow, increasing the RH at 700-mb upwards of 95%. The RH will once again decrease as the evening begins, indicating that the air at this level has lost moisture. The 700-mb level will remain dry on Thursday, but an area of increased moisture will remain just off to the west. Vertical velocity at this level remains unimpressive throughout the majority of the forecast period, with only slight increases represented on Wednesday.

At 850-mb, a rather weak low-level jet (LLJ) is seen over the area from today into early Thursday morning, dissipating by sunrise. The relative humidity at this level is much more intriguing--RH values maintain a steady 95% RH from mid-morning to mid-afternoon tomorrow. Considering the high RH at 700-mb, rain is rather likely during this time period tomorrow. By early evening tomorrow, this level of the atmosphere will also begin to dry out, with significantly less moisture over Columbia by Thursday. Warm air advection (WAA) peaks over Columbia early tomorrow afternoon, further demonstrating the strong likelihood of both clouds and precipitation tomorrow, as well as the chance for thunderstorms. 

At the surface, high dewpoint temperatures are to be expected primarily tomorrow. CAPE values are not particularly impressive early afternoon tomorrow at about 730 J/kg. However, this value nearly doubles by mid-afternoon tomorrow, reaching 1350 J/kg. PW values are around 1.5" for the majority of the day tomorrow with a K Index range of 30-35 throughout the day tomorrow. The lifted index is below zero around mid-morning, and it continues to decrease throughout the day, reaching as low as -5. The values of indices suggest that heavy rain is possible as the system moves through tomorrow, and that the thunderstorms developing in the afternoon have a moderate chance of being severe.

Forecasters for the next shift should further investigate tomorrow's convective potential as well as rainfall amounts due to the K value.

- Macko

 

Current Conditions at Sanborn Field

 

Monday Night: Becoming cloudy. Low: 58

Tuesday: Cloudy skies. Chance of isolated showers. High: 71

Tuesday Night: Cloudy. Low: 62

Wednesday: Cloudy. Isolated storms in the evening. High: 69

 

Wednesday Night: Cloudy. Scattered showers, possible storms, stopping by sunrise. Low: 63

 

 

 

 

Thanks to IconArchive.com for the icons! 

====================================================================

Discussion:  

With today's tempertures topping out around the mid-70s, the rest of the week looks to be a few degrees cooler. A low pressure system over Arkansas will be the driving force for our weather over the next few days. Cloud cover is expected to increase through the overnight hours with temperatures reaching the upper 50s. Tuesday, the chance for isolated showers will return, skies will remain overcast thoughout the day with high temperatures near 70 degrees. Tuesday night, temperatures will drop into the low 60s with winds coming from the northeast at 5-10mph. Wednesday, temperatures will climb back into the high 60s with a chance of isolated storms during afternoon/evening hours. Overnight temperatures are expected to fall back to the low-mid 60s with lingering showers until daybreak.

- Gromada, Alexander

====================================================================

Forecasters: Gromada, Alexander, Gotsch

Date Issued: 10/4/21  05:00 PM CST

Technical discussion:  

This forecast was generated using the NAM 12Z from 4 October. Its handling of the current low pressure system over the midwest and ridge near the Rockies is more accurate than the GFS in this forecast period.The main focus of this forecast is the low pressure system and the scattered showers it will bring to the region.

250mb: Monday night, the open low in southern Missouri will move farther south and slightly strengthen in the overnight hours. Columbia is under the left entrance region and will be under the center line by morning. A ridge over the CO and KS boarders will push farther northeast. Tuesday will see the low stall out over southern Arkansas and become cutoff. The ridge then pushes into Upper-Midwest area. Moving into Wednesday, upper level winds begin pushing the cutoff low to the northeast. The cutoff low moves over the southeast quarter of Missouri in the overnight hours of Wednesday.

500 mb: Increased positive vorticy from the closed low will be present overnight Monday. During Tuesday evening and night, the vorticty will lessen and become negitive. Wednesday afternoon/evening, strong, but isolated, PVA will become present due to the return of the closed low. after the initial passing of storms on Wednesday evening, the PVA will weaken.

700 mb: Monday overnight, moisture pushes in from NE creating cloudcover overnight. Early Tuesday morning, a line of dry air will cause a break in the clouds. As the day progresses, increased moisture will begin piling into the region. This will continue until Wednesday night as the rain will begin removing moisture from the air and taking it to the ground. Rainfall totals on Tuesday are expected to be no more than .25 inch. For Wednesday, precipitation totals could reach up an inch.

850 mb: The Low Level Jet (LLJ) is currently coming from the northeast, maxing out around 30 kt. Tuesday night will see the LLJ weaken until Wednesday where it picks back up. The LLJ at that time will be coming from the east, wrapping around the low pressure system pulling moisture from the Gulf of Mexico.This will be the main source of moisture for the Wednesday precipitation.

Surface: Throughout the forecast period, surface winds will remain calm. Temperatures will be decreasing tonight, overnight into Wednesday. Tempertures on Wednesday will be hovering around the 70s with winds coming from the northeast.

The main area of concern for the next forecastors will be the stalling upper level low stalling to the southeast of Central Missouri leading to increased chances of scattered showers Thursday afternoon.

 

 

Current Conditions at Sanborn Field

 

 

Monday: Mostly sunny. High: 77

Monday Night: Becoming cloudy. Low: 60

Tuesday: Cloudy skies. Isolated showers possible. High: 71

Tuesday Night: Mostly cloudy. Low: 60

Wednesday: Cloudy. Rain likely. High: 69

 

 

 

 

Thanks to IconArchive.com for the icons! 

====================================================================

Discussion:  

Fall is finally here! A brief boost in the high temperature for Monday will lead us into the upper 70s. A low pressure system to the south will bring in rain and cloudy conditions. As clouds start to move in Monday night, they will keep daytime high temperatures cooler for Tuesday and Wednesday. Increased cloud cover Tuesday night will give way to showers Wednesday into Wednesday night. Total rain accumulations will range from 1/4" to 1/2". 

- Cade, Baker

====================================================================

Forecasters: Cade, Baker, Travis

Date Issued: 10/4/21 10:00 AM CST

Technical discussion:  

Fall-like weather is in store for mid-Missouri this week. The main focus of this forecast period is a cut-off low pressure system over the Lower Mississippi River Valley that will bring sufficient moisture northward to support rain near the end of the period on Wednesday. Both the GFS and NAM had a good handling of the large-scale, upper-level pattern, but the GFS was too warm with initialized temperatures in the Central Plains (by ~10-15 degrees F). This warm bias appeared to continue into the forecast period when compared with the NAM and GEFS members. As such, went primarily with NAM guidance, while looking at the SREF and GEFS plumes to analyze model performance.

The NAM 250-hPa height field depicts another period of unsettled, meridional flow similar to that of last week. The longwave trough sitting over the eastern CONUS that brought a weekend of heavy rain is not quite done with the Midwest yet. As an amplified ridge moves in from the southwest, it pushes the jet stream further into Canada and closes off that pesky LW trough cutting it off from the storm track. That newly cut-off low will park itself over the Lower Mississippi Valley allowing active weather later in the week. 

NAM 500-hPa plot of absolute vorticity shows a weak shortwave propagating along the back side of the LW trough during the day on Monday. This weak disturbance will move in from the north before quickly getting absorbed into the upper low as the system becomes cut off, after which the circulation will sit to the south, bringing in vorticity maxima from the SE.

NAM 700-hPa plots of RH favor moisture, albeit very little, lagging behind the weak disturbance on Monday night into Tuesday morning. This will bring in clouds Monday night that will stick around for the remainder of the forecast period. A brief clearing of the saturated air at this level will be cut short by, our friend, the cut-off low. Widespread saturated air will surge NW into Missouri as the low sits to the south. The NAM omega field favors that the bulk of the forcing for ascent will be confined to the Tennessee and Ohio River Valleys, the reason for which becomes evident at 850 hPa. 

A noticeably lackluster low-level setup is evident in the height/MSLP fields 850-hPa and the surface, respectively. At 850 hPa, a weak LLJ is present over the river valleys mentioned above and terminates and does not continue into Missouri. Moisture convergence associated with the LLJ sheds some light on the abundant saturation and ascent seen at 700-hPa. As such, current thinking is that, while mid-Missouri will see rainy conditions all day, Wednesday, precipitation totals should not approach the >3" that Sanborn Field recorded over the weekend. Much is the same story at the surface where no obvious surface features are evident. 

NAM soundings show an increase in low-level saturation Monday night into Tuesday morning associated with the first, weaker disturbance seen at 500 and 700 hPa. Low-level saturation in the lowest 3km and weak UVM would suggest that isolated light showers cannot be ruled out for Tuesday. The low levels dry out Tuesday night before the entire column rapidly moistens Wednesday morning. Deep saturation exists for the entire day Wednesday not drying out until overnight Wednesday. PW ~1.5 inches and K indices ~30 would suggest that rain may be heavier at times. However, little if any instability does not currently favor convection. Accumulation totals could range from 0.25" to 0.5", but if heavier showers set up, amounts could be locally higher. 

Future forecasters should watch the evolution of this system carefully to narrow down precipitation timing and accumulation as we saw over the weekend that the models drastically underperformed on accumulations. 

- Travis

 

Current Conditions at Sanborn Field

 

 

Friday Night: Cloudy. Chance for isolated showers. Low: 65 

 

 

Saturday: Mostly cloudy. Showers and thunderstorms in the late afternoon. High: 79

Saturday Night: Cloudy. Lingering showers and thunderstorms. Low: 63

 

 

Sunday: Decreasing clouds. Isolated showers possible. High: 75

 

 

Sunday Night: Partly cloudy. Low: 61

 

 

 

 

Thanks to IconArchive.com for the icons! 

====================================================================

Discussion:  

Football fans should prepare to be disappointed as game time weather looks to be wet. Unsettled weather will bring with it cloudy skies and chances of rain all weekend. However, widespread heavy rain doesn't look to be a huge concern. More likely, on and off scattered showers and thunderstorms may cause some headaches for fans hoping to tailgate or spectate. Game day Saturday morning will start off with patchy fog and scattered showers. We may see some dry time and even peaks of sunshine throughout the day. Rain chances decrease into Saturday night and Sunday, but passing showers can not be ruled out. Another morning of patchy fog is likely on Sunday. Mostly cloudy skies will keep  temperatures from going above the upper 70s. Total rainfall accumulations should stay near 0.5 inches.

- Millsap, Ethridge

====================================================================

Forecasters: Millsap, Ethridge, Travis

Date Issued: 10/1/21 5:45 PM CST

Technical discussion:  

Unsettled weather will bring with it repeating wet and dry periods throughout the weekend. The main concern for this forecast is the upper-level shortwave trough that will bring with it multiple chances for scattered showers/thunderstorms. Model consensus and continuity has been less than great for the past several runs. While both the GFS and NAM had a decent handling of the upper-level pattern when compared to GOES WV imagery, the two models differed significantly on precip accumulations, and daytime highs. The NAM had a better handling on initial conditions than its considerably warmer GFS counterpart. As such, went primarily with 12z NAM guidance. Consulted SREF plumes to diagnose model continuity within the NAM. 

NAM upper-level plots of 250-hPa heights, wind, and divergence show a persistent meriodional setup over the CONUS with an amplified ridge over the Mississippi River valley at the time of initialization. An upper-level, cut-off low over the Four Corners region will make its way east over the weekend. As it marches towards the Midwest, low will get absorbed into the larger-scale flow and deamplify into a shortwave trough by the time it reaches the Midwest. Increased divergence ahead of the negatively tilted trough hints at sufficient forcing for ascent over the area by 18z on Saturday. 

500-hPa heights and absolute vorticity tell a similar tale. Increasing PVA will bring broad circulation into mid-Missouri come Saturday afternoon, supporting the forcing for ascent seen at 250-hPa. Dynamically speaking, Saturday looks to be the most impressive for widespread precipitation. 

NAM 700-hPa RH and omega shows quite the mess for the duration of the forecast period. Widespread saturation of the mid-levels of the atmosphere exists over the majority of Mississippi River Valley until the upper low pushes off to the east by Sunday evening. The greatest plume of saturated air is temporally collocated with the impressive dynamics mentioned above. As such, the greatest chance for precipitation looks to be between 17z and 22z Saturday. 

850-hPa height and winds show a less impressive setup than the upper-levels. The lack of a LLJ Friday night into Saturday would suggest an insufficient supply of moisture to support a complete washout with high accumulation totals. A similar story of unimpressive features continues at the surface. MSLP and 1000-500-hPa thickness show a lack of WAA ahead of this system (suggesting moisture advection may be lacking as well). A cold front albeit a weak one is evident from MSLP and surface winds passing through the area by 18z Saturday. The weak nature of this front with little post frontal CAA seen in the aforementioned surface plots will result in very little temperature change. 

NAM soundings show persistent deep saturation beginning Friday night and continuing into Sunday afternoon. However, a fully saturated column is only present for 21z Saturday. These profiles look more consistent with frequently passing scattered showers. Throughout the day, Saturday, the NAM soundings favor a destabilizing atmosphere with CAPE values peaking near 1000 J/kg. This is considerably less aggressive than the less stable GFS soundings. The magnitude of destabilization will be heavily dependent on the extent of sunshine on Saturday. If overcast conditions dominate, CAPE values will remain on the low end. Nevertheless, sufficient instability exists to support convection Saturday into Saturday night. PWATs near 1.5 inches suggest that rain will likely be heavy at times. A quick look at both HRRR and NAM simulated reflectivity support the soundings profiles' suggestions of a much more widely scattered event. Widespread heavy rain looks to stay off to the southeast. A look at SREF dprog/dt shows a telling story of discontinuity between runs. What started as favoring a washout in older runs has trended towards a more widely scattered event. The NAM proper still favors higher accumulations near 0.4 inches with a sharp gradient to the SE. The GFS and GEFS members, on the other hand, are much less aggressive with totals sticking closer to 0.25 inches. Accumulations will be heavily dependent on the intensity of the showers/thunderstorms that move over the rain gauge at Sanborn.

The NAM is much slower to dry out the atmosphere behind the weak cold front than the GFS. As such, lingering showers and thunderstorms look possible Saturday night and into the day Sunday, but overall chances for precip diminish considerably compared to Saturday. 

- Travis

Current Conditions at Sanborn Field

 

 

 

Friday: Mostly cloudy with afternoon showers. High: 80

 

Friday Night: Cloudy. Chance for isolated showers. Low: 65

Saturday: Mostly cloudy. Showers and thunderstorms in the late afternoon. High: 79

 

 

Saturday Night: Cloudy. Showers and storms before midnight. Low: 66 

 

 

 

Sunday: Decreasing clouds. High: 77

 

 

 

 

Thanks to IconArchive.com for the icons! 

====================================================================

Discussion:  

Clouds will move back into central Missouri today preceding some light showers this afternoon. This cloudiness will continue overnight with another round of showers moving through the area. The rain will clear before sunrise Saturday morning, but cloud cover will persist throughout the day. A cold front will push storms through Mid-Missouri Saturday night into early Sunday morning. Light winds and soggy ground conditions lead to a chance for morning fog Sunday morning. No chance of precipitation on Sunday, but the cloudiness will remain throughout the duration of the forecast period. Total rainfall amounts will reach 0.4"-0.6" by Sunday morning. 

-Splater & Schneringer

====================================================================

Forecasters: Splater, Schneringer, Bongard

Date Issued: 10/1/21 10:00 AM CST

Technical discussion:  

 GFS was the model of choice for this forecast period as it was optimal in handling initial conditions as well as precipitation accumulations for the forecast period. SREF and GEFS plumes were also used in determining the quality of the model run. SREF revealed inconsistencies with the NAM run especially in precipitation accumulations where NAM dProg/dt showed a diminishing accumulation even though chart analysis tells a different story. Model soundings from the 06Z GFS run were also utilized in the areas of timing and accumulations of rainfall as well as thunderstorm probability.

At 250 mb the flow continues to be well amplified and meridional across the CONUS. The well established trough to the west that has slowly made its way across the Rockies features a closed low over the Four Corners region Friday morning that will slowly migrate to the northeast by Friday night pushing the upper level ridge currently residing over the Midwest to the east. Strong southwesterly flow in the transitional zone between trough and ridge over the region will persist aloft until Saturday night when the trough and associated frontal system move through the region. By Sunday a post frontal weather regime will preside over the Midwest backing winds around to the northwest and ultimately helping to dry the region out by the end of the period.

The 500 mb upper level model chart again features southwest flow in the upstream region of the trough to the west. Some vorticity exists to the northwest of Missouri Friday but should not influence the region. Copious amounts of vorticity will begin to advect into the central CONUS by 12Z Saturday as the low pressure center associated with the trough pushes into Kansas at that time. Vorticity will push into Missouri by Saturday evening as expected just ahead of the cold front. Frontal passage looks to occur between 03Z and 06Z Sunday which is when we expect highest probabilities of rain and convection for the period. 

In the lower levels moisture values continue to maintain high PWAT values as the region resides in the warm sector of the encroaching mid-lat cyclone. Model soundings for Friday afternoon have any CIN available in the morning eroding away by 18Z opening the atmosphere up to CAPE values of 1200 J/kg. Some question exists as to whether this will lead to convective development as a lack of LLJ or any real dynamical forcing may diminish convective chances. That being said convection cannot be entirely ruled out Friday afternoon. The profile remains moist and promotes scattered showers and rain chances through Saturday evening. Heavy rain will be possible just ahead of the frontal passage Saturday night. After 06Z the profile begins to dry out and a post frontal weather regime builds into the region by Sunday morning as the forecast period comes to a close.

-Bongard