Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/24/21

Area Forecast Discussion
National Weather Service Des Moines IA
658 PM CDT Sat Oct 23 2021 ...Updated for the 00z Aviation Discussion... .SHORT TERM.../Tonight through Sunday/ Issued at 252 PM CDT Sat Oct 23 2021 While weak ridging is pushing across the state today and has fostered a seasonably cool day with light easterly winds, this will change this evening. This is signaled in the GOES-East upper level water vapor imagery, which shows a switch to more westerly or southwesterly flow approaching from the west. This flow and a weak shortwave trough interacting with a surface boundary initiated a convective cluster over eastern Kansas that has been moving through the Ozarks today. This boundary will lift northward as a warm front this evening as surface low pressure moves out of eastern Colorado into central Kansas. With increasing theta-e advection tonight, saturation in the atmospheric column will also be increasing from southern into central Iowa. However, this will likely be slower than models are showing due to the low level, dry easterly flow with forecast soundings from the NAM and GFS showing dry air remaining below 900mb. This dry air will be eventually be overcome and result in numerous showers and storms as increasing QG convergence spreads over the region. There is a low risk of severe weather over southern Iowa, likely toward and after midnight tonight. Forecast soundings at LWD and OTM show that instability grows above an inversion, which will be reinforced by the low level thermal lift. That instability is initially around 500 J/kg by around midnight, but grows with the HRRR, NAM, and RAP showing above 1500 J/kg of elevated instability by daybreak. In addition, 0-6km deep layer bulk shear is around 50 knots, more than sufficient for storm organization. With this environment, the main severe concern will be hail tonight with the inversion likely preventing any wind gusts to reach the surface. Rain and elevated storms will continue on Sunday, particularly over southern and central Iowa, but expand into northern Iowa. The northward progress of the rain will be tempered through the night by a mid-level closed low centered over Hudson Bay that has a cyclonic spin over southeastern Canada, the Great Lakes region, and the northeastern US. This closed low will lose its influence on our area on Sunday as a lead shortwave trough ejects ahead of the parent longwave trough over the western US and Canada. This will allow for showers and storms to push into northern Iowa as the surface low moves eastward out of Kansas and near or just south of the Iowa/Missouri border. This movement will be slow as low pressure becomes stacked in the atmosphere with most locations experiencing a 9 to 15 hour period of a high chance of rain and/or storms. This prolonged period of rainfall, starting tonight and lasting into Sunday, along with precipitable water values topping an inch over northern Iowa to 1.5 inches over southern Iowa and high for October warm cloud depths over 3000m will lead to efficient rainfall. The 00z ECMWF extreme forecast index for tonight through Sunday afternoon is showing a very unusual event based on it 20 year model climatology for this time of year with the shift of tails around 2 indicating an anomalous event. The CMC and FV3 both show the highest amounts amongst the deterministic models of around or over 4" in parts of our southeastern forecast area. Looking at ensemble guidance, the 12z HREF localized probability matched mean shows the 3" QPF contour over southern Davis and Appanoose counties for time period ending 00z Sunday with the event total probability matched mean of 3" QPF contour along and south of Highway 34 and east of I- 35. The 12z GEFS spread is 1.5 to 2.5" while the 6z EPS spread is 1.75 to 3" for the 25th and 75th percentiles at OTM. Further, this southeast forecast area has about a 30 to 40% chance of exceeding 3" of rainfall through 6z Monday according to NBM v4.1. So, there is high confidence in the highest rain totals over our southeastern forecast area and likely eclipsing 2" in many of those areas and perhaps 3" in a few of those areas. These amounts and over a prolonged period are less concerning from a flash flood standpoint given that most areas south of Highway 30 have a 3"+ over 6 hour flash flood guidance. Further, contingency hydrographs over southern Iowa show below action stage rises on rivers with OTMI4 5` below flood stage, MOLI4 2` below flood stage, and CHTI4 3.5` below flood stage given maximum rainfall. Given the prolonged nature of the rainfall and high flash flood guidance along with a buffer in the contingency hydrographs, have held off on issuing a flood watch. Rises on streams and rivers and ponding in low lying and poor drainage areas seems likely and could be exasperated in localized areas if harvested field stubble clogs culverts/drainage ditches. Another severe risk may evolve ahead of the low pressure as it tracks just south of the Iowa/Missouri border with the warm front in the vicinity of the same border. Most soundings solutions from the 9z/12z runs of the HRRR, RAP, NAM, and GFS show the surface inversion remaining, meaning that the warm front does not make it or does not make it far into southern Iowa. This would mitigate concerns about surface based storms and tornadoes. Did come across one sounding that showed a one or two hour window with surface based potential at OTM with 2000 J/kg of instability and 40 knots of deep layer shear, but this seems like an outlier case given the preponderance of guidance. Finally, winds from the east will increase and be gusty on Sunday, especially over northern Iowa, as the low pressure passes over northern Missouri. As the low pressure moves into northern Illinois, rain showers will wrap around on the back side of the low. Initial guidance showed an hour or two of a rain-snow mix over north central Iowa, but it is likely that drier air will arrive before the air is cold enough to support it. .LONG TERM.../Sunday night through Saturday/ Issued at 252 PM CDT Sat Oct 23 2021 The long term weather pattern remains active. Monday will start out quiet and cooler than normal as ridging moves across the state, followed by a slight rebound to near normal Tuesday as low level return flow sets up. The next weather-maker is on tap for mid week. Deterministic forecast models are in general agreement that the low now over the Pacific will continue to dig and deepen as it pushes eastward across the CONUS and into the midwest around mid week. With the energy still well off the west coast, confidence remains low in forecast timing and details from Tuesday night into Thursday, since small changes in the track of the surface low and associated fronts will cause notable differences in the sensible weather. Thus the general thinking is that there will be a round or two of precip mid week and seasonable temperatures. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 652 PM CDT Sat Oct 23 2021 Deteriorating conditions during the period as cigs lower and precipitation increases from south to north. This evening will remain primarily VFR but possibly IFR conditions will reach KDSM/KOTM prior to 12z followed by lowering conditions at the other sites. East wind overnight will become breezy to even gusty at times Sunday. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Ansorge LONG TERM...Dubberke AVIATION...Donavon
Area Forecast Discussion
National Weather Service Goodland KS
850 PM MDT Sat Oct 23 2021 .UPDATE... Issued at 850 PM MDT Sat Oct 23 2021 The latest short range guidance has come around to the GFSLamp guidance in producing visibilities of 1/4 mile or less in dense fog for all but Hitchcock and Red Willow counties. Have gone ahead and issued a Dense Fog Advisory that is in effect until 11z. KITR (Burlington, CO) reported 1/4sm in dense fog about 20 minutes ago. && .SHORT TERM...(This evening through Sunday) Issued at 315 PM MDT Sat Oct 23 2021 A fairly difficult forecast unfolded for today as persistent low clouds and dense fog hung around all morning and thus far into the afternoon. Visibility is very slowly improving at KOEL and KCBK with 1/2 mile now being reported by their AWOS. This lingering cloud cover has severely impacted afternoon highs for west Kansas and Nebraska as highs have been lowered into the 50s. RAP analysis and visible satellite show an advancing low pressure system moving off of the Rockies with additional clover emanating onto the Colorado Plains. The low is expected to be fairly quick moving as it will be out of the area around 18Z tomorrow. As the low approaches the chances for light rain increases starting late this afternoon and into the night. The best potential for rain showers appears to be along and east of Highway 83 with less than 0.05" expected. Confidence has also increased in the development of fog again. Guidance indicates areas of fog could begin developing as early as 03Z and becoming more widespread throughout the night and through the morning. Locally dense areas may occur as the atmosphere is more moist and with convergence from the approaching low. It also was hard to ignore the fact that Colby, Oakley and Scott City all were below 1 mile visibility for the majority of the day. A Dense Fog Advisory may be needed by the upcoming shifts but held off for now until more certainty in the magnitude comes into focus. Overnight lows for tonight will be warmer than the past nights in part to the cloud cover and rainfall potential. Overnight temperatures look to be in the mid 40s to low 50s across the area. Sunday, rain showers come to an end around 18Z as clouds and any lingering fog dissipate. The afternoon looks to be mainly clear as temperatures are forecasted to rise into the 60s to 70s. If the clouds do hang around longer then a similar situation to today may play out with cooler high temperatures being realized. Breezy to gusty winds look likely in wake of the low with sustained winds of 15-20 knots and and perhaps wind gusts up to 30 knots, potentially higher at times. The clear skies persist into Sunday night which will allow radiational cooling to lower temperatures into the 30s again with frost again possible. Sunday night into Monday morning, some guidance has again been hinting at a window for fog development, have left out of the forecast for now due to lack of confidence. .LONG TERM...(Monday through Saturday) Issued at 305 PM MDT Sat Oct 23 2021 The upper ridge moving over the High Plains on Monday continues east over the Plains states on Tuesday. The pattern over the central and western U.S. becomes more amplified as the trough moving through the Intermountain west deepens into a closed low over the southern Rockies Tuesday night, emerges over the Panhandle region Wednesday morning, and moves across Oklahoma by Wednesday evening. Timing and location differences in the position of the upper low start to show up on Thursday as the low moves into the Mississippi valley area with ridging returning to the central High Plains Thursday night and Friday ahead of the next upper trough moving into the Rockies by Saturday. Monday into Tuesday morning will be dry across the forecast area with the ridge in place aloft and high pressure at the surface moving to the east. As the upper pattern amplifies and is reflected at the surface by a low developing over eastern Colorado Monday morning, the pressure gradient and winds speeds begin increasing across the central High Plains on Tuesday with sustained southerly winds around 20 kts and gusts near 35kts by mid day. Expect the surface trough to move across the area Tuesday evening followed by a cold front with winds turning northwest and showers moving across the forecast area with a few thunderstorms possible across mainly the eastern sections of the forecast area Tuesday evening. Some of those thunderstorms could become severe mainly over the far eastern sections of the forecast area east of a line from McCook, Nebraska to Quinter, Kansas. Temperatures on Wednesday will be 10-15 degrees cooler with showers continuing eastward with the low pressure system along with gusty winds on the back side of the low. Showers move out of the area Wednesday night and winds diminish as the system continues to the east. Dry and cooler conditions remain through Thursday with dry and slightly warmer daytime temperatures on Friday and Saturday. With mostly clear skies and lighter winds, expect early morning temperatures Friday and Saturday morning to dip into the lower 30s for possible areas of frost/freeze. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 735 PM MDT Sat Oct 23 2021 KGLD...sub VFR conditions are expected from taf issuance through 15z under stratus and fog. Winds begin the period from the northeast under 10kts backing to the north then northwest at similar speeds through sunrise Sunday morning. Northwest winds gusting 25kts or so are expected shortly after sunrise with VFR conditions expected. KMCK...sub VFR conditions are expected from taf issuance through 15z under stratus and fog. Winds begin the period from the east under 10kts backing to the northeast then north at similar speeds through sunrise Sunday morning. Northwest winds gusting 25kts or so are expected by mid to late morning with VFR conditions returning. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...Dense Fog Advisory until 5 AM MDT /6 AM CDT/ Sunday for KSZ001>004-013>016-027>029-041-042. CO...Dense Fog Advisory until 5 AM MDT Sunday for COZ090>092. NE...Dense Fog Advisory until 5 AM MDT Sunday for NEZ079. && $$ UPDATE...99 SHORT TERM...TT LONG TERM...LOCKHART AVIATION...99
Area Forecast Discussion
National Weather Service Hanford CA
215 PM PDT Sat Oct 23 2021 .SYNOPSIS... Northwesterly breeze across the district today as northwest flow aloft continues. A very strong and wet storm system will approach the region on Sunday. Breezy to gusty conditions are possible along the coastal range Sunday afternoon through the morning on Monday. Heavy rain below 8,000 feet and snow above 8,000 feet will begin impacting the area late Sunday, and will continue through Monday afternoon. Residual, upsloping showers may persist along the Sierra Nevada and Tehachapi mountains Tuesday. Drier and warmer pattern Wednesday and afterwards. && .DISCUSSION... Cooler than normal conditions continue today after the passage of yesterday`s cold front. Latest observations indicate that most areas won`t get much above 70 degrees this afternoon, which is several degrees below average. Starting tonight, a robust storm system will begin to dive out of the Gulf of Alaska and approach the area tomorrow morning. This storm system will feature an impressive fetch of moisture along the cold frontal boundary, forming an Atmospheric River. Ahead of the cold front, breezy conditions may occur starting mid day Sunday through Monday morning along the Coastal Range, so a Wind Advisory has been issued for wind gusts up to 45 mph. As the upper low dips south and then to the east on Sunday, upsloping snow showers will begin at very high elevations along the Sierra Nevada. Snow levels will start initially around 10,000-11,000 feet on Sunday afternoon ahead of the cold front. Light rain may also begin at lower elevations of the forecast area, including the norther San Joaquin Valley by late in the afternoon Sunday. The cold front is progged to trek southward through the evening Sunday evening and Sunday night, bringing moderate precipitation rates just ahead of it. The system overall has been trending slower, so we did push back the start times for our products. The new start of the Flash Flood Watch for the Creek Fire Burn Scar will be 5 PM Sunday, with the Flash Flood watch for the KNP, Windy, French, and SQF Burn Scars/Fires now starting at 11 PM Sunday. The Winter Storm Watch for the Sierra Nevada above 8,000 feet has also been upgraded to a Winter Storm Warning, with a 5 PM start time on Sunday. See our Winter Storm Warning for more details. The most intense rainfall/snowfall rates will come with the cold front itself which is forecast to pass through the region very late Sunday night into Monday morning. Some high resolution model guidance such as the HRRR and the ensemble HREF are showing that rainfall rates of around 1" per hour are possible in the Sierra Nevada below the snow line early Monday morning along the cold front. Intense rainfall of 1"/hour pose a risk to recent burn scars, with debris flow flooding possible. Lesser rainfall rates around .5" an hour are predicted for the San Joaquin Valley and the coastal range as the cold front passes through. Some flooding along the Coalinga Foothills may be possible as well as nuisance flooding in the San Joaquin Valley Monday morning. Heavy rain will continue in the Sierra Nevada as the front pushes southward through Fresno County sometime early to mid morning on Monday. As the front pushes even further south later in the morning rainfall and snowfall rates should diminish as moisture along the front gets wrung out over the Sierra Nevada. The front should exit the region late on Monday. Rainfall totals for the valley may range from 1-2 inches in the northern SJ valley to .5-1 inches in the southern SJ Valley. Rainfall totals in the Sierra Nevada below 8,000 feet may reach 4-6 inches Fresno County and northward, with 2-3 inches in the Sierra Nevada in the Tulare County Mountains. Up to 1 inch of rain may fall in the Kern County mountains through Monday afternoon. Snowfall totals of 2-4 feet are also predicted for the Sierra Nevada above 8,000 feet through Monday evening, with the most snow falling in Marpiosa and Madera Counties. There are some indications that a rumble of thunder or two will be possible in the SJ valley Monday afternoon associated with post-frontal instability. We`ll see how that threat evolves with upcoming model runs. After Monday, residual, upsloping-natured showers are favored across the north and western facing slopes in northwest flow. A ridging pattern looks to emerge after Tuesday in the Eastern Pacific. This will lead to a warming and drying trend across the region, however blended model guidance is still favoring below average temperatures for the region. && .AVIATION...Areas of MVFR in low clouds and precipitation with local mountain obscuring IFR over the Sierra Nevada north of Kings Canyon, extending south over the Tehachapi mountains through 0z Sunday. IFR visibility in heavy rain and snow in the Sierra Nevada after 18z Sunday. Otherwise, VFR conditions will prevail across the central CA interior for the next 24 hours. && .AIR QUALITY ISSUES... None. && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from Sunday evening through Monday evening for CAZ322-329>331. Flash Flood Watch from Sunday afternoon through Monday evening for CAZ318-320-325>327. Winter Storm Warning from 5 PM Sunday to 11 PM PDT Monday for CAZ323-326>331. Wind Advisory from 11 AM Sunday to 11 AM PDT Monday for CAZ300- 304-308. && $$ public...Bollenbacher aviation....Bollenbacher
Area Forecast Discussion
National Weather Service Wichita KS
642 PM CDT Sat Oct 23 2021 .SHORT TERM...(This evening through Sunday) Issued at 324 PM CDT Sat Oct 23 2021 ...Updated for the 00Z Aviation Forecast... FORECAST HIGHLIGHTS: * Conditional isolated strong/severe storm threat this evening across portions of central and south-central Kansas. * Strong/severe storm threat far eastern Kansas Sunday afternoon. * Potential for widespread rain and embedded thunderstorms Tuesday night through Wednesday night. THIS EVENING-TONIGHT...Cannot rule out a stray thunderstorm this evening, generally along/west of the Flint Hills and south of I-70, in vicinity of a dryline/warm front triple point, and also near a remnant outflow boundary from convection early this morning. Latest RAP, NAM, and HRRR suggest boundary layer heating/moistening may be just enough to weaken the cap sufficiently for a rogue storm or two to form. However, there are some negatives, namely lack of large scale mid/upper forcing, along with mid-level temperatures warming with time this evening. If deep moist convection can indeed breach the cap, sufficient combination of instability/shear would support an isolated large hail/damaging wind threat. Will continue to monitor observational trends. Otherwise, thinking brunt of widespread showers/thunderstorms overnight will be well northeast of the forecast area, within a zone of strong/deep warm advection and moisture transport north of the warm front. However, thinking a smattering of isolated to widely scattered showers/storms could increase for locations generally along/east of I-135 after midnight, within a zone of rich mid-level moisture amidst increasing large scale ascent ahead of the approaching shortwave. This activity will likely remain below strong or severe levels. SUNDAY...Still thinking the greatest severe threat Sunday afternoon- evening will be just east of the forecast area across far eastern Kansas and Missouri, as a powerful shortwave and associated stout mid/upper speed max overspreads a moist/unstable warm sector. The cold front reaches the Flint Hills by about lunchtime, with storms possibly initiating as early as 2-3pm. Consequently, will hold onto a conditional severe threat as far west as Yates Center-Fredonia- Independence. Strong/deep wind fields in concert with moderate to strong instability will be supportive of severe weather. Long clockwise-turning hodographs and lower LCLs may also support a tornado threat, even if storms tend to go more mixed mode and/or linear with time. But once again, the greatest threat will be probably be just east of the forecast area. .LONG TERM...(Monday through Saturday) Issued at 324 PM CDT Sat Oct 23 2021 TUESDAY-THURSDAY...Attention then turns to the mid-week period, as model consensus progresses another deep/potent upper trough east across Mid-America. Timing and amplitude of this next system is still in question, with run-to-run and model-to-model consistency issues abounding. The GFS remains the faster solution, supporting lower rainfall totals, and rain chances only Tuesday night through Wednesday morning. In contrast, the ECMWF and to some extent the Canadian model remains slower and deeper, supporting a more prolonged rain event Tuesday night through Thursday, with much greater rainfall totals. Furthermore, while the overall synoptic pattern favors at least a mention of strong to severe storms, suspect the big limiting factor will be limited moisture return and associated instability. Stay tuned for later forecasts. FRIDAY-SATURDAY...Building upper ridging and associated large scale subsidence should support mostly quiet weather Friday through next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 635 PM CDT Sat Oct 23 2021 MVFR cigs are expected to expand into central KS this evening as a warm front lifts northward across the area. The best chance to see reduced flight categories tonight will be along the I-70 corridor where IFR/LIFR are anticipated with some drizzle developing in a moist upslope regime. As the front moves eastward during the morning hours on Sunday, flight categories will improve from west to east as drier and more subsident air overspread the region. We could see some transient showers or perhaps an isolated storm impact south central and southeast KS tonight as we remain within the warm sector with some increasing large-scale forcing for ascent as the shortwave trough approaches but the bigger concern will be widespread LLWS impacting all of south central and southeast KS through the overnight and early morning hours. VFR will return from west to east during the morning hours on Sun. && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 66 73 43 65 / 30 10 0 0 Hutchinson 64 69 40 64 / 20 10 0 0 Newton 65 71 42 63 / 30 10 0 0 ElDorado 66 73 43 63 / 30 10 0 0 Winfield-KWLD 68 77 45 67 / 30 10 0 0 Russell 52 64 37 62 / 20 20 0 0 Great Bend 53 66 38 63 / 20 10 0 0 Salina 58 66 39 63 / 30 20 0 0 McPherson 64 68 40 62 / 20 10 0 0 Coffeyville 69 79 46 66 / 30 30 10 0 Chanute 68 77 45 63 / 30 30 0 0 Iola 66 76 45 62 / 30 30 0 0 Parsons-KPPF 69 78 45 65 / 30 30 10 0 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...ADK LONG TERM...ADK AVIATION...MWM
Area Forecast Discussion
National Weather Service Lincoln IL
903 PM CDT Sat Oct 23 2021 .SYNOPSIS... Issued at 240 PM CDT Sat Oct 23 2021 Moderate to heavy rain with a potential flooding threat especially north of I-72 will impact central Illinois from very late tonight through early Monday morning. In addition, severe thunderstorms may impact central Illinois, especially Sunday evening. Another storm system is expected in the middle of the week. && .UPDATE... Issued at 902 PM CDT Sat Oct 23 2021 Some spotty light rain showers have been detected on radar over east central and southeast IL this evening in weak isentropic lift aloft. However, the significant precipitation should develop toward midnight from NW MO to southern IL as a low level jet strengthens ahead of a strong surface low moving into SW KS. This precipitation should continue to intensify and expand northeastward into the central IL forecast area overnight, along with some thunderstorms developing in elevated instability aloft. Have made some minor updates to PoPs to delay initial arrival of precipitation slightly, as well as to account for earlier evening showers/sprinkles. Otherwise, lows ranging from mid 40s north of I-74 to mid 50s south of I-70 look on track. && .SHORT TERM...(This evening through Sunday) ISSUED AT 240 PM CDT Sat Oct 23 2021 Light rain is detected on radar and via observations south of I-70 near Flora and Olney as the first wave of rain along the warm frontal zone moves east. A sharpening warm front is most noticeable in the north-south dew point gradient as well as the surface pressure field as extensive cloudiness and convection has muddled the temperature field somewhat. Expect on and off rain showers south of I-70 with perhaps a break in the late evening before the first prominent round of steady rain begins to move into central Illinois late tonight/early Sunday morning as isentropic upglide serves to expand the area northward while the warm front moves little. Additionally, the 12z HREF indicates an area of elevated MUCAPE impinging on areas mainly south of I-72 where a hail threat will accompany the morning activity. Some areas may see a brief break during the early afternoon as the warm front moves northward through Illinois. This will allow unstable air in the warm sector to enter into central Illinois with the latest HRRR indicating 1500-2000 J/kg of SBCAPE south of the front until diurnal cooling starts and values slowly decrease. Exactly how far the warm front lifts northward will be a major factor not only in who might see the greatest tornado threat should a surface-based storm initiate along this boundary, but also how much of central Illinois is overspread by unstable air in the warm sector and might be prone to a greater severe wind threat in the evening in association with convection ahead of the surface cold front. Current timing has a pre-frontal line of convection crossing the CWA late Sunday evening. The severe threat should end during the early morning hours on Monday. Back to the rainfall...once rain re-strengthens north of the warm frontal boundary a swath of fairly continuous moderate to heavy rainfall is forecast predominantly north of I-72. Combining the early morning rainfall, the afternoon rainfall, and the rain ahead of the cold front Sunday evening, fairly widespread totals of 1-3 inches are expected north of I-72 while some locations may see totals of up to 4-5 inches. A Flash Flood Watch has been issued for this area in coordination with neighboring offices. Lower rainfall totals are expected south of this line with potentially more of a break between periods of rain, but totals of 1-2 inches will still be common. .LONG TERM...(Sunday night through Saturday) ISSUED AT 240 PM CDT Sat Oct 23 2021 The severe and heavy rain threats are expected to wind down by around 3 am Monday, with the surface low moving across north central Illinois Monday morning. Breezy north winds and slightly below normal temperatures are expected during the day on Monday as the surface high moves into the Midwest. Another fairly cool day is anticipated Tuesday with light winds before the next system approaches the central US. WPC clusters show noticeable differences in timing and location of the next trough with about 20% of members indicating the base of the trough moving through Illinois on Thursday, while the other clusters show weaker solutions over the southern Plains or a still deep but farther south/closed solution. At any rate, since differences in timing/strength still exist will go with the blended solution for precip chances other than slowing progression of precip Wednesday in coordination with neighboring offices. It`s still uncertain whether a closed low will continue to influence central Illinois into late week (65%) or we`ll be in dry northwest flow (35%). && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 645 PM CDT Sat Oct 23 2021 Decreasing cigs and vsbys are expected to spread from south to north overnight as a strong storm system and associated warm front approach the area. Expect MVFR cigs at KSPI and KDEC by 02Z-03Z, and northward to KPIA and KBMI by 05Z-06Z. Rain with a few thunderstorms will develop by a few hours later, bringing MVFR vsbys as well. Expect conditions to further deteriorate by morning, with IFR cigs expected by around 12Z. Showers and a few possible thunderstorms will continue through the day, however the I-72 terminals KSPI-KDEC-KCMI could see some improvement in cigs to MVFR and a few more breaks in precipitation after the warm front lifts through the area by around 21Z. A strong line of thunderstorms is likely to arrive shortly after 00Z at these terminals, deteriorating conditions again. && .ILX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from 1 AM CDT Sunday through Monday morning for ILZ027>031-036>038-040>048. && $$ UPDATE...37 SYNOPSIS...AAT SHORT TERM...AAT LONG TERM...AAT AVIATION...37
Area Forecast Discussion...UPDATED
National Weather Service Chicago/Romeoville, IL
910 PM CDT Sat Oct 23 2021 .UPDATE... 909 PM CDT No significant evening changes to the forecast for the stout autumn system moving in Sunday and persisting into Monday, and no changes to the Flash Flood Watch or Lakeshore Flood Advisory. New 00Z model data is just starting to arrive, and full evaluation of that will be done by the overnight shift. Just a few notes here. A Wind Advisory will need to be considered by the overnight shift for not only lakeshore counties of Illinois but even inland along/north of I-88. The pressure gradient is strong over that area much of tomorrow night. It`s the region on the north side of a quick moving low pressure around 1001 mb (lowest 5th percentile for the time of year in the central Illinois area). Forecast soundings from many models show 40+ knot speeds within 1,500 ft of the ground and the low-levels being somewhat mixed. The 00Z HRRR also has several hours of 40-45 mph gusts in the northern third of the CWA tomorrow night. Advisory or not, the key message is consistently windy late day Sunday through Monday A.M., and continuing all Monday on the shore. The 18Z guidance and the 00Z guidance that has arrived remains consistent on the low pressure path across the southern CWA. The strongest moisture convergence on the nose of a 60 kt low-level jet, and at least transient frontogenesis at and above this level, is generally just ahead of this low path in the warm advection. The Flash Flood Watch covers this area of numerous hours of heavy rainfall well, though do think at least minor/poor drainage type flooding in parts of the metro further north are a good bet too given the low path and time of year (leaves impacting efficient drainage). Will need to keep an eye on potential for exceeding 2 inches of rainfall into Kane, DuPage, and all of Cook Counties. The 00Z HRRR, much like the 18Z long range run, continues to show the surface warm sector knocking on the door to the southern CWA. We still have strong doubts on whether the effective air mass can get into the far southern CWA, but the kinematic parameter space is quite noteworthy. The threat gradient for severe weather may end up being quite sharp somewhere in central Illinois and the details of where may not be able to fully emerge until convective effects are resolved into the day tomorrow. Finally, this evening`s river forecasts from the North Central River Forecast Center (NCRFC) do take into account the full forecast QPF of this system. This is bringing multiple river points in the southern CWA to flood stage. At this time these are all to the minor flood category, but any boost in QPF may result in possibly an uptick -- namely the Vermilion, Kankakee, Iroquois, and Little Calumet River basins. MTF && .SHORT TERM... 235 PM CDT Through Monday... Synopsis: A powerful autumn storm system will take shape over the next 24 hours and eventually bring a multitude of inclement and potentially hazardous weather to the area Sunday into Monday. Water vapor imagery early this afternoon depicts a powerful Pacific jet stream beginning to crash onshore the west coast. This strong jet stream (130-150kt at 250mb) will translate eastward into the central Plains tonight resulting lee cyclogenesis in the left exit region of this jet. This cyclone will intensify and close off a mid-upper level circulation as it moves east toward the mid Mississippi Valley Sunday night into early Monday. Southerly winds are already transporting moisture northward from the Gulf of Mexico north into the southern and getting into the central Plains. Strong low level jet (>50kt @ 850mb) will develop tonight in response to the developing lee cyclone and help accelerate the northward transport of moisture in advance of the system. Early this afternoon, a warm front at the surface extends from central Kansas east to downstate IL. As the cyclone develops tonight, look for warm front to begin lifting northward with strengthening low level jet resulting in significant low level theta-e advection into strengthen low-mid level frontal system. The strengthening low-mid level frontogenesis combined with the strong theta-e advection should result in a blossoming area of showers and thunderstorms to the north of the sfc warm front. This activity will lift north into the our CWA late tonight into tomorrow morning, with this likely to be the first of multiple rounds of showers and some thunderstorms as the system moves rather slowly eastward across the region. Hydrology: Models continue to advertise near record levels of moisture availability with precipitable water values near or above 1.5 inches pooling near and north of the quasi-stationary boundary. The slow moving nature of the east west boundary combined with at least waves of strong forcing, at first via theta-e advection and frontogenesis and eventually from the DCVA with the cyclone itself, should be quite effective at translating this abnormally moist atmosphere into effective heavy rainfall production. Higher resolution models continue to advertise narrower swaths of well over 4" inches of rain in spots mainly south of I-80. Even the lower resolution guidance has widespread 2-3"+ rainfall amounts south of I-80 and one inch plus over most of the CWA. While exact locations in the various models vary, the idea of swaths of >4" of rain is a pretty consistent and concerning signal in the convective allowing guidance. SREF probabilities of 2" of rain in 6 hours are in the 30-80% range over a sizable portion of our southern CWA Sunday evening, which is close to the 6 hourly flash flood guidance (which isn`t taking into account antecedent rainfall during the day Sunday). A preponderance of the evidence supports issuing a flash flood watch for our southern CWA. Not uncommon for warm sector convection to our south to sometime retard the northward moisture transport in these strong systems, reducing rainfall totals to the north. In this case, round one of will occur tonight and into Sunday, prior to any meaningful convection in the warm sector. Widespread convection is expected to develop tomorrow afternoon/evening across Missouri, however backing low-mid level flow owing to the closing off of the mid-level low should actually drive the weakening remnants of the Missouri convection north into our CWA. Latest runs suggest the rainfall with the trowel on the back side of this system later Sunday night into Monday will probably be mostly north of the areas most likely to see heavy and potentially flooding rainfall on the "front" side of the storm. However, thermodynamics would suggest a potential for a lake enhancement to the rainfall over northeast Illinois Sunday night into Monday. So while during and intensity of the rain stands a lower probability of producing substantial flooding in northeast IL north of I-80, could still see problems with standing water, particularly in poor drainage areas. Probably a flood advisory type situation, if anything. Convection: Some thunderstorms are likely very late tonight into Sunday morning in the warm air advection regime over mainly our southern CWA, though weak instability should result in mainly a heavy rainfall threat. It appears very likely that our CWA will remain safely north of the warm front with minimal severe weather threat in our area. As the sfc low track east near I-80 the warm sector could briefly make it into the southern portions of our CWA later Sunday night, but instability is likely to be too weak that time of day for a meaningful severe weather threat. However, could see a bit of an uptick in lightning activity later Sunday night as upper low approaches and we briefly poke into the warm sector. Winds/Waves/Lakeshore Flooding: Tightening pressure gradient in advance of the surface low will result in gradually increasing easterly winds, particularly starting late Sunday afternoon into Sunday evening. Over land, mixing is not expected to be particularly efficient in the easterly flow, but given the strong pressure falls and tightening gradient it should be breezy/windy Sunday night over northern IL. Of greater concern, relatively chilly air mass in place north of the warm front flowing over the record warm Lake Michigan water will result in very efficient mixing of the higher momentum air to the surface over the lake and along western shores of the lake. Bufkit forecast soundings from most models suggest sustained winds over the lake of around 30kt Sunday night into Monday morning with deep mixing in the marine boundary layer likely to transport down gusts of 40-45kt. These strong easterly winds will should result in large battering waves along the Illinois shore Sunday night into Monday. While the wind direction initially will not be favorable for a big storm surge, the magnitude of the winds should result in some response in lake levels which combined with the large waves will result in a lakeshore flood threat. Winds will back to northerly and begin to slowly ease, but likely continue at gale force until later Monday afternoon. So while the winds may begin to ease slowly Monday, the wind direction will result in a more favorable fetch probably continuing the lakeshore flood threat. Will be hoisting a lakeshore flood advisory for this time frame. - Izzi && .LONG TERM... 300 PM CDT Monday Night through Saturday... The main concern in the medium-long range is the potential for another period of wet weather Thursday into Friday, though confidence is very low. Temperatures will average near normal. On Monday night, 850 mb temps will cool to near or below 0C, which will set up respectable lake induced thermodynamics with 850 mb to lake deltas up to 17C, equilibrium levels of 6-7kft, and a couple hundred J/kg of CAPE. Drying and subsidence should push in from the west later overnight or Tuesday morning, but before that, think some lake effect showers are a decent bet. Unidirectional brisk north-northeast flow from the surface to well aloft entails very little wind shear and decent inland penetration of lake effect showers. Introduced lower chance PoPs for this. Weak high pressure ridging will bring a quiet and seasonable Tuesday and Tuesday night. Attention then turns to the next strong short-wave trough ejecting across the high Plains area, with lee cyclogenesis Tuesday. Global guidance is in good agreement in sharp short-wave ridging across the western Great Lakes on Wednesday in response to the digging trough to the west, and continued dry surface high pressure influence. As such, there has been a decided drier trend on Wednesday, so continued to trend PoPs downward. Model variance grows substantially after the Wednesday daytime period, greatly lowering confidence and predictability. The southern Plains short-wave is forecast to close off at the mid and upper levels over the Mid South on Wednesday, with strong secondary cyclogenesis possible over the lower-mid MS Valley. Key word here is possible cyclogenesis, as the operational ECMWF is much farther south and slower with the key mass fields than the GFS and CMC. There are some ECMWF ensemble members still similar to the much more robust GFS and CMC suites, though the mean generally supports the operational. While vice versa is true for the other guidance, spread is massive. What this all entails is that greatly disparate outcomes remain plausible for later Wednesday night through Friday, ranging from another wind driven soaking rain (GFS and CMC) to a period of lighter rain later Thursday into Friday and much less wind (ECMWF operational). Trended PoPs lower Wednesday evening when model consensus is primarily dry, but then maintained NBM thereafter, with PoPs peaking at likely on Thursday PM. Coming off the significant rain event tomorrow into Monday, another soaker would increase hydro concerns. Suffice to say, it will take some time to resolve the model variance, so stay tuned. Turning ahead to Halloween weekend, medium-long range guidance trends point toward seasonable to slightly above normal temperatures and drier conditions, with a surge of chilly air possibly waiting in the wings to start November. Castro && .AVIATION... For the 00Z TAFs... Concerns in this period are the expected deteriorating conditions Sunday morning as several waves of RA move over the area through Sunday night. VFR conditions will continue for all sites tonight, with wind speeds under 10 knots and directions VRB but mainly between NNE and ESE. Mid-level clouds will quickly thicken toward daybreak, followed a few hours later by an increasingly lower low-level cloud deck. Low- end MVFR ceilings should become common by late morning, with widespread IFR ceilings during the afternoon and evening. The potential exists for a period of LIFR ceilings Sunday evening. Precip may begin as spotty -SHRA prior to mid-morning, but quickly increase in coverage and intensity during the late morning. Frequent periods of MVFR visibility are expected. The RA will become more convective in nature Sunday evening, with a few embedded TS possibly nearing ORD/MDW from the south. Beginning around daybreak, winds will remain E/ENE through Sunday night while strengthening. Frequent gusts to 30 knots and sporadically to 35 knots are expected Sunday evening. Kluber && .MARINE... 235 PM CDT Upgrading the gale watch to a gale warning. The gale threat appears most substantial in the Illinois nearshore waters, but will be upgrading Indiana as well even though gales appear very marginal there until Monday. Confidence is high in 40-45kt easterly gales Sunday night into Monday morning, with a couple of the more aggressive models even hinting at a threat of a couple brief low end storm force gusts. Winds should begin to slowly subside Monday as they back to more northerly direction. - Izzi && .LOT WATCHES/WARNINGS/ADVISORIES... IL...Flash Flood Watch...ILZ019-ILZ020-ILZ021-ILZ023-ILZ032-ILZ033- ILZ039-ILZ105-ILZ106-ILZ107-ILZ108...4 PM Sunday to 10 AM Monday. Lakeshore Flood Advisory...ILZ006-ILZ103-ILZ104...7 PM Sunday to 7 PM Monday. IN...Flash Flood Watch...INZ001-INZ002-INZ010-INZ011-INZ019...4 PM Sunday to 10 AM Monday. LM...Gale Warning...LMZ740-LMZ741-LMZ742-LMZ743...5 PM Sunday to 9 PM Monday. Gale Warning...LMZ744-LMZ745...8 PM Sunday to 9 PM Monday. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Pendleton OR
829 PM PDT Sat Oct 23 2021 .UPDATE...Scattered light showers developed this evening across south central WA and north central OR, and showers will track northeast and out of the forecast area over the next few hours. Any additional showers the remainder of tonight until around 3 AM will be isolated in a southwest flow aloft. Meanwhile, precipitation associated with a deep low off the eastern Pacific will spread inland. Between 3-5 AM, precipitation will develop along the OR Cascades and as far east as Bend and Warm Springs. Surface gradients will also tighten for increasing southerly winds and breezy/windy conditions between midnight and sunrise. High wind warnings and wind advisories were issued across most of eastern OR and far southeast WA from 5 AM to 5 PM Sunday. The wind advisory was expanded to include the John Day Basin. The low offshore is impressive with a surface low possibly as deep as 944mb tomorrow! This could be one of the lowest surface pressures in the northern Pacific in history. Strong southerly pressure gradients combined with a low level jet around 55kts at 850mb will bring strong winds to portions of the area. The area likely to receive the strongest winds will be along the Oregon Blue Mountain Foothills where several different high resolution models are showing sustained winds of 40-45 mph with gusts 60-70 mph. Downsloping winds off the Eagle Caps may also create similar gusts in Joseph. Precipitation amounts of 0.25-0.5 inch are expected for most of the area Sunday and Sunday night. Although rainfall amounts are not significant, the moist ground will lead to better potential for fallen trees with weak roots. Forecast looks good, and only minor updates were made. Again, the John Day Basin was added to the Wind Advisory. Wister/85 && .PREV DISCUSSION... /issued 450 PM PDT Sat Oct 23 2021/ SHORT TERM... Tonight through Sunday night...Broad westerly flow will remain over the region early before the flow becomes more southwesterly tonight. The gradient will tighten in advance of a very strong low off the Oregon and Washington coasts that will move northeastward toward the British Columbia coast by Monday morning. The tightening gradient coupled with strong low level jet support will bring increasing south winds on a southwest to northeast axis from central Oregon across the Blue Mountain foothills, the Blue Mountains and into portions of Wallow County. The ECMWF Extreme Forecast Index (EFI) depicts this area well, with a broad area between 0.8 and 0.9 across eastern Oregon and smaller areas between 0.9 and 0.95, especially near the Blue Mountains. The latest NBM 4.1 continues to show very strong wind gusts in these areas and also across portions of Wallowa County. The NBM continues to be supported well overall by the HRRR guidance. As a result, the previously issued high wind watches will be upgraded to high wind warnings and portions of Wallowa County have been added to the warning as well. Additionally the same NBM 4.1 and HRR Guidance also supports strong winds across central Oregon, though with values not quite as high, so wind advisories have been issued for these areas. By Sunday evening, the strongest winds should be subsiding. As far as rain chances, there will not be much for the remainder of today into tonight. However, as jet support increases and several short waves move through, there will be an increasing chance of showers during the day on Sunday, from west to east, with rain chances decreasing during the late evening and overnight hours. Most locations will end up with 0.25 inches or less, though some of the higher terrain could receive upward of 0.50 inches with locally higher amounts. High temperatures on Sunday will range from the lower 50s to around 60, with overnight lows mainly in the 40s tonight and Sunday night, except in the 30s across central Oregon. LONG TERM... Monday through Saturday...A series of troughs moves across the Pacific Northwest through the end of the week keeping us windy and wet. The strongest conditions in the extended period look to be on Tuesday when the heaviest precipitation and strongest winds should occur. Widespread QPF totals of 0.1-0.25 inch are possible, with local amounts exceeding 0.5 inch, with gusty winds 20-30 mph also expected. Into Thursday a brief period of weak ridging coupled with southwesterly flow will slightly warm up the region, with widespread mid to upper 60`s possible. Another trough behind that though will drop us again on Friday, with slightly below average highs then expected on Saturday. But a stronger ridge is forecast to build in on Saturday, which should help to finally dry us out and calm the weather pattern down by the end of the long term and just beyond. Goatley/87 AVIATION...00Z TAFs...The deep low pressure system off the eastern Pacific will have a large impact on the weather east of the Cascades, and there are aviation hazards with it. A strong low level jet will likely result in LLWS with 40-55kt winds just above the surface for most of the TAF sites on Sunday. Surface winds will also be considerably stronger tomorrow at the terminal airports, especially along the Blue Mtn Foothills and Central OR. While downsloping winds will keep CIGS high with little precipitation at ALW and PDT, the other sites may have MVFR or less. Strong low level upslope near the Yakima Valley may keep CIGs and VSBY low at YKM for most of the day. Wister/85 && .PRELIMINARY POINT TEMPS/POPS... PDT 43 61 43 60 / 40 50 80 20 ALW 46 60 46 62 / 40 50 70 30 PSC 45 60 43 63 / 40 70 70 20 YKM 41 56 38 57 / 20 90 20 40 HRI 45 61 42 63 / 40 60 60 20 ELN 38 52 37 54 / 20 90 40 40 RDM 40 60 33 55 / 50 90 30 20 LGD 44 55 41 56 / 20 70 60 40 GCD 43 55 42 57 / 30 80 70 30 DLS 45 57 42 60 / 20 90 20 60 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Wind Advisory from 5 AM to 5 PM PDT Sunday for ORZ505-506-511. High Wind Warning from 5 AM to 5 PM PDT Sunday for ORZ049-050- 502-503-507-508. WA...High Wind Warning from 5 AM to 5 PM PDT Sunday for WAZ029-030. && $$ SHORT TERM...85 LONG TERM....87 AVIATION...85
Area Forecast Discussion
National Weather Service Pueblo CO
246 PM MDT Sat Oct 23 2021 .SHORT TERM...(This evening through Sunday) Issued at 240 PM MDT Sat Oct 23 2021 Currently... A flat short wave trough was located over the central Rockies early this afternoon. Quite a few showers were noted with it over NW CO. Over most of the NWS PUB area, lots of wave clouds were noted, leading to mostly cloudy skies over the region. Temps over the region varied quite a bit, with L80s over far SE plains to U60s over the Palmer Divide. Over the mtns and valleys, temps ranged from the 40s to L60s. Winds were still relatively light as it was breezy over the higher terrain, and the gap flow area in the greater Walsenburg region. Tonight... Progressive wave will move across the region bringing some light snow to the higher terrain, with the brunt of it falling after midnight. Best chance of some light accumulating snow will be over the CONTDVD, with the central mtns being favored. Breezy conditions will keep up across the region and this will allow temps to be rather mild tonight, with lows on the in the 40s across the plains and 20s in the mtns and valleys. West slopes will see the (relative) warmest temps due to downslope flow. Tomorrow... Overall expect a very nice day. A few showers may still be lingering early in the day across the central mtns. It may be a bit breezy early but winds should decrease by late morning nearly all areas. Temps tomorrow will be several degrees cooler than today and we should see more Sun tomorrow across the region. /Hodanish .LONG TERM...(Sunday night through Saturday) Issued at 240 PM MDT Sat Oct 23 2021 ...Strong system moves across Tuesday... Significant Pacific storm system will affect the region starting late Monday and last into Wednesday. This system will likely bring a period of snow to all of the mountains, with the CONTDVD region being most favored. I`d expect to see amounts of 3 to 6 inches with locally heavier amounts on the west slopes of the divides. Give the strong winds that will accompany this Pacific weather system we will likely need some highlights for some of the higher terrain areas for the Tuesday time frame. Winds will be concern with this system all areas. By Tuesday afternoon expect winds of 20 to 30 mph with gusts to 40 mph over the plains. RH values will approach critical values and near critical to critical (RED FLAG) conditions will be possible on Tuesday. It will also be quite gusty over the mtns and valleys, with stronger winds over the passes. NBM guidance came in with some scattered POPs across all of the plains Tuesday night and this is a change from earlier guidance. Although the GFS still is rather progressive with this system (and keeps a westerly component to all of the winds), the EC is much more amplified and indicates some wrap around precip with this system. Looking at the individual ensemble members from the EC and GFS, there area several members that show some healthy qpf along the I-25 corridor, especially down in the greater Raton Mesa region (However there are several members that show NO precip at all). Given that this is a rather very dynamic system, I would not be surprised if a stronger solution verifies with this event. This system is rather warm so any precip on the plains that falls Tuesday night will likely be liquid, with some snowflakes possible over the Palmer Divide in the evening hours. Wednesday... System will be slow to push east,, however expect brunt of precip will be out of the region by Wednesday morning, with just some lingering showers in the C mtns and far eastern plains early. The primary concern will be winds on Wednesday as the system will rap up over the central plains and this will lead to strong gusty NW winds over the region during the daylight hours. RH values may be rather low and this may lead to some near critical fire weather conditions once again over the plains. Thursday into Saturday... Dry with mild temperatures. Sunday... Another system will move across the region, this system will be dropping out of Canada, so we may see some cooler air move into the region for Sunday. Ensemble temp data shows a very large spread in the member values, so some rather cool air will be possible with this system. /Hodanish && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 240 PM MDT Sat Oct 23 2021 VFR conditions are expected during the next 24 hours at all 3 taf sites, KPUB, KALS and KCOS. Breezy conditions will last into the early evening hours with winds then weakening. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...HODANISH LONG TERM...HODANISH AVIATION...HODANISH
For frequently asked questions about the Area Forecast Discussion
Area Forecast Discussion
National Weather Service Tulsa OK
702 PM CDT Sat Oct 23 2021 .DISCUSSION... A quiet but unseasonably warm evening is underway across the region. South winds will stay up thru the night as low pressure continues to organize over the southern High Plains. The winds and higher dewpoints (in the 60s) will yield rather toasty overnight lows for tonight. In fact, with a forecast low of 70 on Sunday morning at TUL, this would be only the 2nd year on record with a low of 70 or higher on Oct 24th, the other year being 1939 with the record of 71. There is an elevated storm over the eastern TX Panhandle, giving some credence to the latest HRRR runs, which suggest a small cluster of elevated storms will spread across northwest and north central OK later tonight. Some of this activity may graze our area as well and have thus stuck close to the previous forecast of slight chances across northeast Oklahoma north of I-44 after midnight tonight. && .PREV DISCUSSION... /Issued 617 PM CDT Sat Oct 23 2021/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. Initial VFR conditions will give way to a period of MVFR cigs as low level wind fields increase and bring increased moisture to the region. That said, will continue with WS remarks overnight and into tomorrow morning. Cigs will likely come up a little to low VFR by late morning/early afternoon. A cold front will move through the NE OK sites mid afternoon, however any TSRA chances will be east of those sites. AR sites and KMLC have better chances for a period of TSRA, however that looks to be at or after 00z- just beyond the scope of this issuance. PREV DISCUSSION... /Issued 256 PM CDT Sat Oct 23 2021/ DISCUSSION... Convection continuing to straddle OK/KS/MO borders this afternoon but is diminishing, slowly but surely. Attention for the forecast now turns to the potential for severe weather Sunday afternoon and evening. Warm and moist airmass continues to stream north this afternoon and will remain in place ahead of a potent low-amplitude wave moving across the western U.S. and its attendant cold front. Overnight lows tonight will remain much above normal, only a few degrees below normal highs for the date. Most of the available CAM guidance hints at some elevated showers or possibly a t-storm developing late tonight into Sunday morning in WAA regime across northeast OK. Cold front is expected to push into northeast OK around 18z Sunday, with scattered storms eventually developing along the boundary by mid afternoon. In addition, 3km NAM and to a lesser extent the HRRR hint at open warm sector convection well ahead of the front from far eastern OK into western AR. Should any of this manage to root in the boundary layer, they would pose a threat for all modes of severe given the impressive low level shear. Storms that develop along the front also would likely be severe, though low level shear is less favorable by later part of the day and especially by 00z. Eventual transition to a more linear storm mode through the evening implies damaging winds become more prevalent. Front will sweep southeast through the area Sunday night with more seasonable temps for Monday. Moisture should begin to surge back north tuesday ahead of another potent upper system. Model differences remain significant in handling the system with the ECMWF continuing to depict a deeper cutoff low moving across Texas Wed into Thu. Blended guidance will continue to be followed with highest thunderstorm chances Tuesday night into Wednesday, followed by cooler and breezy conditions late in the week with at least a small chance of lingering showers into Thursday. && $$ Lacy