Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/18/19

Area Forecast Discussion
National Weather Service La Crosse WI
1049 PM CDT Sat Aug 17 2019 .SHORT TERM...(This evening through Sunday) Issued at 213 PM CDT Sat Aug 17 2019 Plenty of features to note in early afternoon observational analysis. The weak ridging at the surface and aloft that has kept us dry today continues to push off to the east while a weak shortwave trough approaches. To the south, a warm front was draped across northern Illinois westward into Iowa with a fairly sharp accompanying wind shift. To the northwest, a much stronger shortwave trough and surface cold front were moving through the Dakotas. Each of the aforementioned features will play a key role in the weather, namely precip chances, through the short term period. The first concern will along the warm front late this afternoon as the weak shortwave moves through. A few of the CAM solutions (HRRR/ESRL HRRR) along with the RAP hint at some isolated activity developing along the front sometime in the 20-23Z timeframe. Latest SPC mesoanalysis shows around 1000-1500 J/kg of MUCAPE along the front, so it will just be a matter of how much convergence will be seen. In addition, around 40 kts of deep layer shear could be enough to yield some degree of organization to some of the storms, though veer-back-veer wind profiles won`t help. Attention then turns to further development along and near the warm front late tonight as a fairly strong low level jet/moisture transport signal are progged to point into southwestern portions of the forecast area. Overall trend in the RAP through the day has been slightly weaker with this feature, but it still remains plenty strong as of the 17.17Z run to get storms to develop. In addition, the cold front will be approaching the area around the same time, with convection well underway ahead of it. While deep layer shear will be on the downward trend through the night, low to mid level shear will increase as the low level jet strengthens, and the RAP has consistently progged 2000-3500 J/kg of MUCAPE to build into the forecast area prior to convection developing/arriving. While all of this seems to point toward strong to severe storms, timing won`t be until after midnight (probably closer to 8-9Z), so storms would likely be elevated, any severe weather reports /hail, wind/ likely being fairly isolated. In addition, while the airmass will be supportive of heavy rain, the cold front moving in should keep things fairly progressive and preclude any widespread flooding threat. The front will continue eastward on Sunday with perhaps a few lingering showers during the day, especially southwest WI. Plenty of cloud cover is expected for much of the day, with temperatures topping out in the mid 70s to mid 80s. .LONG TERM...(Sunday night through Saturday) Issued at 213 PM CDT Sat Aug 17 2019 A glorious Monday is followed by return flow from the south as high pressure departs to the east. Instability builds during the day based on consensus of the deterministic 17.12Z models...with MLCAPE values in the 1500-2500 J/Kg range. This is ahead of a cold front shifting in from the west. However, warming mid-level temperatures look to provide a capping inversion that may be hard to break given the degree of forcing in the low-levels. Low-level moisture convergence varies along the front, and the moisture transport signal does as well in the lowest 2 km. Wind shear is marginal as well but there are suggestions of a mid-level wind max slightly upstream of the front. So, Tuesday will need to be monitored for thunderstorm potential as there are at least a few ingredients that are in play to favor storm development. Forecast rain chances are in the 30-40% range. Wednesday-Saturday... After a cold front moves through, Canadian high pressure builds into the region. This will bring a refreshingly cooler airmass into the region as well as drier weather for Wednesday. This dry period is expected to last through Friday. Later in the week, the high pressure moves to the east and warmer air returns. Although low precipitation chances creep back into the region (~20%), Saturday is questionable regarding precipitation as the flow && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1049 PM CDT Sat Aug 17 2019 A line of strong to severe thunderstorms will move across the TAF sites in the 08Z to 12Z timeframe tonight producing gusty winds, brief heavy rainfall, and frequent lightning. Winds gusts of 30 to 40 kts are a good bet and cannot rule out isolated stronger gusts. Ahead of the line, plan on scattered thunderstorms with lightning and brief heavy rain the main threats. Plan on IFR conditions with the thunderstorm activity then MVFR stratus sets up across the area in the wake of the storms. Conditions gradually improve from mid Sunday morning into early Sunday afternoon as high pressure builds in. Valley fog is possible at KLSE after midnight, closer to sunrise Monday morning. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...CA LONG TERM...Aufforth AVIATION...Wetenkamp
Area Forecast Discussion
National Weather Service Grand Forks ND
949 PM CDT Sat Aug 17 2019 .UPDATE... Issued at 944 PM CDT Sat Aug 17 2019 Any lightning has moved east or south of the area with a few lingering showers remaining. These should end over the next few hours with a dry overnight and day setting up for Sunday. UPDATE Issued at 646 PM CDT Sat Aug 17 2019 Line of convection continues to move east across the MN counties stretching from Waskisk to Detroit Lakes to near Wheaton. Will continue to see a mostly sub severe storm wind threat with an occasional 60mph severe gust possible as storms push to the east the remainder of the evening. Strongest instability exists in areas mainly from Grant Co and southwards so did include Grant in severe thunderstorm watch with more organized convection moving into the area from the west. && .SHORT TERM...(This evening through Sunday night) Issued at 303 PM CDT Sat Aug 17 2019 Convection timing and strength tonight will be the main challenges for the period. Showers and thunderstorms that initially went up along the surface trough axis this morning have mostly moved off to the east and weakened, and there has been some decent sunshine and heating out ahead of the main shortwave and cold front that is entering the western CWA this afternoon. SPC mesoanalysis page has ML CAPE of 1500-2000 J/kg with not much CIN left over our southwestern counties. Deep layer bulk shear is not huge at around 25-35 kts, but still adequate and the shear should improve as the shortwave comes into our area. Web cams of the cumulus field west of Fargo show not much vertical development yet, and day cloud phase RBG curve is mostly liquid in that area. However, further north in western Grand Forks county, there is a bit more vertical development of cumulus starting and even the Fargo cu field has started to improve. The more recent HRRR runs have some convective initiation in that area, so might not be a bad first guess. Will continue to keep an eye on developing storms and should start to see more activity in the next few hours. At this point it seems cells going up are rather isolated but with mean wind close to the orientation of the cold front, that may not last very long. CAMs seem to show the first initiation around GFK moving eastward into MN with a bigger convective complex of thunderstorm clusters later this evening possible. This does not seem completely out of the question and some quarter inch hail and wind gusts to 60 mph will be possible mainly in southeastern ND and western MN. Heavy rain could also be an issue in some areas as PWAT values are around 1.2 inches but there could be some training echoes along the boundary. There is good agreement on the frontal boundary and the showers and storms pushing east of our counties around 09 to 10Z tonight, with most of our area going dry by morning. Some clearing in the northwestern counties could drop temps down below 50 degrees. Sunday should be dry with cooler temps mostly in the upper 60s to mid 70s even with sunshine. Winds will pick up out of the southwest Sunday night ahead of the next trough, and temps should stay in the 50s with decent mixing. .LONG TERM...(Monday through Saturday) Issued at 303 PM CDT Sat Aug 17 2019 Scattered thunderstorms will be possible again during the overnight hours Monday into Tuesday with quieter weather likely for middle part of the work week. Rain and storm chances pick up again heading into the upcoming weekend. Monday through Monday night... Long and medium range deterministic and ensemble guidance is in fairly good agreement in the chance for thunderstorms late Monday into early Tuesday. Guidance depicts zonal flow over the northern Rockies inducing lee troughing over eastern MT/western ND through the day Monday. Higher theta-e air will advect northward into the region in response to the lee troughing and will support at least moderate levels of instability by late Monday. A 50-70 knot mid level jet over southern Canada will support enough deep layer shear to introduce the potential for a few strong to severe storms. Thunderstorms will likely develop by the evening hours as an eastward advancing cold front pushes through the region. Tuesday through Wednesday... High pressure is expected to build into the region in the wake of Monday night`s cold frontal passage. Temperatures during this period will be slightly below seasonal normals with highs in the mid to upper 70s for Tuesday and Wednesday. Thursday through Saturday... Long range guidance is again in reasonable agreement about the approach of an upper level shortwave from the Pacific Northwest into the northern Plains Thursday into early Friday. The approach of this wave (and attendant surface low) and eastward exit of the surface high will induce breezy southerly return flow through the Plains that will allow temperatures to warm slightly into the upper 70s and low 80s for Thursday afternoon. Showers and thunderstorms will be possible along a cold front as it moves eastward through the region. However, it should be noted that difference between guidance gives low confidence regarding the timing of precip during this Thursday/Friday timeframe. After this period, divergence in model solutions throws uncertainty into the extended forecast. However, the general trend is that nearly zonal mean flow aloft will continue to allow shortwave troughs to quickly propagate through into the region and bring periodic rain/thunderstorm chances heading into the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 646 PM CDT Sat Aug 17 2019 Line of storms will impact BJI over the next 2 hours. After that the TAF period looks to be mostly VFR with west to northwest winds at 5 to 15kt with gusts tomorrow afternoon around 20kts. There is some guidance bringing in MVFR CIGs for a brief period tonight at TVF and BJI. Will monitor before including in the next set of TAFs. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...JK SHORT TERM...JR LONG TERM...AM AVIATION...JK
Area Forecast Discussion
National Weather Service Goodland KS
716 PM MDT Sat Aug 17 2019 .UPDATE... Issued at 712 PM MDT Sat Aug 17 2019 Just completed an update. Main change was to adjust pops based on current trends and also on the HRRR that has been very consistent in some redevelopment in the next couple hours. So lingered/raised pops in the southern portion of the area where it has been consistent in this development. Realize currently that not much is going on now. However, based on the numerous outflow boundaries, low level jet setting in, and shortwave trough still moving through, will keep the severe watch going. Otherwise adjusted hourly trends winds, temperatures, dewpoints, and sky cover. && .SHORT TERM...(This evening through Monday night) Issued at 234 PM MDT Sat Aug 17 2019 The focus for the short term forecast is on the chance of thunderstorms and the potential for severe storms moving across the forecast area this afternoon and evening. With an uncapped atmosphere and good instabilities existing across the forecast area mainly where surface dewpoints are in the middle to upper 60s ahead of a surface trough, along with surface convergence near the surface trough and a short wave trough aloft approaching in the upper westerly flow, expect the storms developing over the higher terrain to the west to grow and become more numerous through the afternoon and into the evening as they tap into the additional moisture available mainly east of the Colorado border. Expect scattered storms to develop and move through the area mainly between 3pm-11pm this afternoon and tonight. While large hail is possible with some of the stronger storms, the primary threat appears to be damaging winds gusts that could be 65 mph or greater. The past few days models have been advertising the possibility of fog developing across the forecast area in the wake of storms moving across the region. However, in the latest runs, the production of fog has diminished with only isolated locations seeing a possibility of fog. Have removed a mention of fog as a result, but this will need to be watched over the next few days as there is the potential of some locations to receive rainfall followed by clearing skies and light winds that would be conducive to the production of fog. Once the short wave trough aloft moves through the region overnight tonight, an upper ridge will begin to amplify over the southern Rockies and southern and central high plains region through mid day Tuesday. Also expect mainly high pressure across the region during that time that will initially cool the temperatures somewhat on Sunday with highs mainly in the 80s that will quickly rebound into the 90s on Monday and Tuesday. .LONG TERM...(Tuesday through Saturday) Issued at 219 PM MDT Sat Aug 17 2019 Tuesday morning, an upper level ridge will extend over the Central High Plains with ridge axis just to our west, over the Rockies. A surface high will be in place over the southeastern U.S. and the Tri-State area will be under southwest flow aloft. Through the day, flow will become zonal over the region and a lee cyclone is expected to develop Tuesday afternoon. Expected high temperatures will be in the 90s. A cold front will move into the area from the north during the day Wednesday. Temperatures will be cooler with highs in the low to mid 80s and lows in the 50s and 60s. The cooler temperatures will continue into Thursday. Showers and thunderstorms will again be possible on Wednesday. Thursday, additional chances for showers and storms will be possible as a shortwave moves through the region. Friday into Saturday, temperatures will rebound back to near normal, ranging form the mid-80s to low 90s across the area. Lows will return to the low to mid-60s. Currently not anticipating precipitation for Friday into the start of the weekend. The ridge will shift east, over the forecast area. Models are indicating a possible shortwave moving in from the northwest at the end of the forecast period, however, taking into account this is seven days out and disagreement in models, have opted to keep the forecast dry for now. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 525 PM MDT Sat Aug 17 2019 Vfr conditions are expected through the period at this time. For Kgld, the winds will be variable in direction up to 15 knots for the first hour of the forecast due to a thunderstorm that just moved through. At 01z the winds will be east at 10 knots and shift to the southeast 7 knots at 04z. Those winds will continue until 15z when they will shift to the north at 11 knots as a front goes through. At 19z the winds will shift to the northeast at 9 knots. For Kmck, the winds will start out east at near 9 knots. From 01z to 03z thunderstorms will be in the vicinity of the site as winds become southeast at 13 knots. The winds will shift to the east around 8 knots and continue until 05z. These west winds will stay west until 13z when they shift to the north at 8 knots. Around 21z those winds will shift to the east at 7 knots. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...LOCKHART LONG TERM...AW AVIATION...BULLER
National Weather Service Wilmington OH
932 PM EDT Sat Aug 17 2019 .SYNOPSIS... Weak disturbances moving across the region will bring several chances of thunderstorms for the early part of the week. A better chance of storms will come as a cold front pushes through the area late Wednesday. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Dry conditions are in place across our area this evening. An area of thunderstorms has developed in the past couple of hours back across southern Illinois. This is in an area of better ML capes and along the nose of a developing 925 mb low level jet. This low level jet is forecast to strengthen somewhat as it shifts northeast across central Indiana into northwest Ohio through the overnight hours. ML capes across that region are less unstable due to the convection and remnant clouds cover from earlier in the day, although there is are still some more decent elevated instability present. The overall trend of the HRRR and the RAP has been to allow for some additional development eastward into Indiana over the next few hours before weakening it some as it pushes northeast across mainly northwest portions of our area later tonight. Will trend the forecast this way and allow for a period of lower chance pops across about the northwest half of our fa through the early morning hours overnight. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... A weak boundary across the lower Great Lakes combined with a mid level impulse will bring another chance of storms, mainly in the afternoon and evening to northern counties. Cloud cover may be a bit more in the north as well which could keep highs in the mid 80s. Elsewhere, readings will rise into the upper 80s and lower 90s. Lows will be near persistence. && .LONG TERM /MONDAY THROUGH SATURDAY/... Quasi-zonal midlevel flow will remain entrenched across the lower Great Lakes region through the first part of next workweek, with a quasi-stationary/oscillating front stretching from northern OH westward through northern IL. The front will gain a bit of southward momentum late Monday into Monday night as heights fall aloft and surface high pressure builds east through the heart of the Great Lakes region by Monday night. However, the front will become somewhat washed out across the area by early Tuesday, with southwesterly surface flow resuming area-wide by Tuesday afternoon. And with the remnant boundary lingering about the area on Tuesday, will maintain a chance PoP across most of the ILN FA -- especially during the diurnally-favorable time frame of afternoon/early evening. The hottest day of the extended period will likely be Monday ahead/south of the aforementioned E-W oriented front across the northern Ohio Valley -- with heat index values in the upper 90s possible across a large portion of the local area Monday afternoon. Tuesday will still feature warm and humid conditions -- although potentially not quite as warm as will be the case for the first day of the workweek. And by Wednesday, mid/upper level troughing across the Great Lakes region will become more pronounced as a stronger/better push of cooler/drier air arrives by Wednesday night into Thursday with the passage of a cold front. The arrival and subsequent progression of the cold front through the region on Wednesday will likely bring with it the best chance for widespread showers and storms during the entire long term period. While the specifics of the this system and the corresponding impacts on the sensible weather locally are still a bit uncertain, feel confident in increased chances for precipitation on Wednesday into Wednesday night before cooler and drier air arrives for the final part of the workweek. Although the front /and corresponding clouds and precipitation chances/ may linger near/south of the Ohio River early Thursday, the influx of drier air in from the north should help shunt the best afternoon/evening storm chances further south/away from the ILN FA. Therefore, will maintain a dry fcst past midday on Thursday for the entire area. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Mainly just some mid and high level clouds across the area early this evening as the earlier pcpn has dissipated. The HRRR is suggesting some redevelopment is possible later tonight along a strengthening low level jet. There is some uncertainty with this but if this were to develop, it looks like it would most likely affect KDAY and possibly KCMH/KLCK in the 06-09Z timeframe. Will cover this threat with a VCSH. Otherwise expect VFR conditions through the remainder of the TAF period. OUTLOOK...Thunderstorms possible Tuesday and Wednesday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS... NEAR TERM...JGL SHORT TERM... LONG TERM...KC AVIATION...JGL
Area Forecast Discussion
National Weather Service Lincoln IL
749 PM CDT Sat Aug 17 2019 .SYNOPSIS... Issued at 309 PM CDT Sat Aug 17 2019 Thunderstorms moved across central Illinois during the morning hours. Through the afternoon, mostly cloudy skies were the rule with only a few widely scattered showers seen over the area. Temperatures were around 80. Scattered thunderstorms are again expected to develop tonight, moving southeast over the region through the morning hours. More scattered storms will be possible on Sunday. Highs on Sunday will be in the mid 80s && .UPDATE... Issued at 748 PM CDT Sat Aug 17 2019 Monitoring some explosive convection just south of the CWA and east of St Louis this evening. Some of these storms may spread into southeast counties of the CWA south of I-70 during the evening hours. Corridor of mid to upper 70 dew points with temperatures in the 80s is contributing to an axis of 3000+ J/kg MLCAPE this evening while latest SPC RAP mesoanalysis indicates that 30-35 kts of deep layer shear is in place across the area. This should support strong to possible severe storms in the area, though fairly nebulous forcing over the area should help to keep coverage isolated to widely scattered. Will have to monitor storms closely over the next couple hours, then anticipate coverage to further diminish as the boundary layer stabilizes after sunset. No significant changes in thinking for storms redeveloping to the west tonight, with storms still expected to move into the area late tonight into early Sunday. && .SHORT TERM...(This evening through Sunday) ISSUED AT 309 PM CDT Sat Aug 17 2019 Storms moved off to the east in the morning hours as jet max aloft pulled to the east into southeast MI-northern OH. Airmass has shown some signs of reloading as MUCAPES in the 2000 range over central sections. However lack of forcing has kept only few showers during the day. Aloft, the main upper level short wave/trof seen in moisture channel data now into MT to western WY and this will continue its eastward movement tonight. Ahead of system, diflence aloft progged to strengthen and coupled with the 850mb moisture transport seen in SPC meso analysis already feeding northward from KS into NE. Expect convection to fire in the advection region, and advect to the east southeast, with the main convection moving into IL late tonight, but further to the north than today. Problems are that the short range convective models are different in the positioning of the storms moving into the area, with strengthen, timing and movement. These factors complicate the forecast and so tried to go with a middle of the road, more generic chance of storms at this time. For Sunday, expect storms that develop to track over area, mainly during the morning hours, with some minor afternoon redevelopment possible, similar to today. .LONG TERM...(Sunday night through Saturday) ISSUED AT 309 PM CDT Sat Aug 17 2019 Only significant feature is the the frontal boundary that finally tries to move through on Tuesday into Wednesday, with scattered storms possible during that period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 636 PM CDT Sat Aug 17 2019 Yet another tricky forecast on tap this evening with thunderstorm chances comprising the main forecast challenge. Unstable conditions are in place across the region, though tempered slightly across central Illinois with cloud cover in place. While cannot completely rule out an isolated pop-up thunderstorm across central Illinois this evening, it remains a low likelihood to directly impact the terminals. Better chances for showers and thunderstorms will occur late tonight into Sunday morning as another thunderstorm complex is progged to form over the plains and race east overnight. As has been the case the past couple nights, there remains quite a bit of uncertainty in the precise track of this system, and several models now hint that storms may stay north of the terminals altogether. Given the uncertainty, will maintain a VCTS mention during the most likely window of storms for the area. If confidence increases in storms moving across central Illinois as opposed to northern Illinois, a tempo or prevailing TSRA will need to be introduced into the forecast. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Deubelbeiss SYNOPSIS...Goetsch SHORT TERM...Goetsch LONG TERM...Goetsch AVIATION...Deubelbeiss
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
650 PM CDT Sat Aug 17 2019 .SHORT TERM... 228 PM CDT Through Sunday... Several forecast challenges/concerns this afternoon through Sunday morning, initially with respect to any additional scattered shower/storm development this afternoon and then more widespread shower and storm potential overnight into early Sunday morning. In the near term, focus revolves around another incoming mid-level wave across eastern Iowa this afternoon, which is expected to gradually shift eastward across northern IL through the remainder of the daylight hours. Despite the atmosphere being considerably worked over this morning, a cu field is already evident across parts of eastern IA and northwest IL out ahead of the wave in an increasingly unstable environment, along with some isolated to scattered radar returns (no lightning as of yet). Given the anticipated arrival of greater support aloft and some recovery across northeast IL/northwest IN, will continue the mention of scattered showers and thunderstorms across the forecast area this afternoon...most likely between 20z and 00z before support strips off to the east and a lull in activity is expected to become the rule this evening. There remains a non-zero chance through this afternoon for a stronger storm or two, mainly capable of producing gusty winds and perhaps some hail. However, focus rather quickly shifts to the tonight into early Sunday time frame as an active pattern is expected to remain in place. Additional, potentially widespread, showers and storms appear likely during this time frame as no real change to the overall pattern and environment is anticipated, with highly active mid- levels and strong warm air advection supported by a stout LLJ expected to be in place across the region. Latest trends continue to suggest a complex of thunderstorms developing across southern MN/Iowa late this evening into the early overnight hours before tracking eastward toward the CWA toward sunrise Sunday. While confidence isn`t stellar, feel the most likely timing for storms to track through the region is somewhere between 09-14z, with most guidance in agreement with this timing. The exception is recent HRRR runs, which have significantly slowed shower/storm chances to after 12z/Sunday. there will remain a severe weather threat with these storms, primarily in the form of strong/damaging winds, and to a lesser extent, large hail. Given lots of deep layer moisture (PWATs progged AOA 1.75 inches), heavy downpours with at least an isolated flooding risk will also be a concern. Beyond Sunday morning, would expect some drier conditions to return for part of the day, although with lingering surface trough/boundary across the region, wouldn`t be surprised to see an additional isolated shower and/or storm develop late in the day/early evening. High temperatures Sunday expected to range from the low-upper 80s across the forecast area with afternoon heat indices near 90 degrees for many areas. Gillen && .LONG TERM... 226 PM CDT Sunday Evening through Saturday... A surface trough will cross the area Sunday evening into Sunday night. This will lead to lingering chances for isolated to scattered showers and thunderstorms during the evening, with the threat decreasing from northwest to southeast into the overnight. Surface high pressure will move in from the west Monday and depart Tuesday. The high will bring modestly drier air with it and somewhat cooler temps for Monday with highs in the lower 80s north to mid 80s south. Winds shift southerly Tuesday bringing warmer and more humid back into the area. An upper trough will cross the area with a weak surface reflection accompanying it. Will need to see what kind of thunderstorm chances will be present with this, but guidance seems to be more focused on something tracking more to the south of the area. Will keep chance pops going Tuesday night and Wednesday morning. A deeper upper low will move across Ontario Wednesday pushing cooler and drier air into the local area as another surface high builds in, this time from the north. Guidance is at odds with some of the details with the GFS favoring slightly active upper flow which suggests subtle chances for shower/thunder development late this week. Will continue with a dry forecast from Wednesday afternoon into the weekend but continue to keep an eye on how the pattern evolves. MDB && .AVIATION... For the 00Z TAFs... 650 PM...Forecast concerns include... Possible mvfr cigs this evening. Isolated showers/thunderstorms this evening. Thunderstorms Sunday morning. Strong/gusty southwest winds Sunday afternoon. There is still a chance for an isolated thunderstorm this evening with a cell near dbq to the west and another near beh to the east. Not currently expecting anything more than isolated coverage so have left out mention from the tafs except for vicinity shower mention at rfd this evening. Focus then shifts to the predawn hours Sunday morning when a broken line of thunderstorms is expected to move across northwest IL and then across the rest of the terminals through mid morning Sunday. These storms will likely have some gusty wind potential as well as possible ifr cigs/vis. Confidence is low for additional convection Sunday afternoon into Sunday evening. It appears any new thunderstorms Sunday afternoon would be east or south of the terminals with perhaps a better chance for thunder later Sunday evening. There is still patchy mvfr cigs across the area early this evening and these are expected to move northeast and scatter within the next few hours. Wind will remain south/southwest under 10kts this evening...likely shifting a bit more southwest ahead of the expected thunderstorms Sunday morning. Wind directions behind the storms will be dependent on how widespread the activity becomes but a south/southeast direction for a short time is likely before winds shift to the southwest. Forecast soundings show quite a bit of wind in the low levels through mid afternoon. The sooner clouds clear and mixing begins the more likely gusts could be stronger than currently indicated. Wind speeds/gusts will diminish with sunset Sunday evening. cms && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSCHICAGO WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Pueblo CO
810 PM MDT Sat Aug 17 2019 .UPDATE... Issued at 806 PM MDT Sat Aug 17 2019 The Red Flag Warning was allowed to expire at 8 PM given winds have calmed down and RHs are rising across the warned area. ~Line && .SHORT TERM...(This evening through Sunday) Issued at 244 PM MDT Sat Aug 17 2019 Low level moisture still hanging on over the far sern plains at mid- afternoon, though surface winds have taken on a wly component nearly to the KS border of 21z, and dewpoints were falling at most locations. Suspect convection along the Palmer Divide will have a difficult time building southward late this afternoon and evening given unfavorable surface winds and weak low level convergence, though will have some low pops along the KS border to account for potential of weak convection forming on the wrn edge of the deeper moisture. Confidence is low, as HRRR suggests any activity will stay north, though satellite and radar have shown some weak storms over Baca county earlier this afternoon. Storms end quickly this evening, with clearing skies overnight. Surface cold front then drops south through the plains early Sun morning, with nly winds over most of the area east of I-25 by midday. Only impact of the front will be slightly cooler max temps over the plains, as low level winds don`t turn upslope/ely quick enough to aide in convective development. Farther west, air mass over from I-25 westward will remain very dry, with only some paltry alto-cumulus over the mountains by late afternoon. Max temps over the mountains and interior valleys will likely warm slightly as mid level temps nudge upward, with little change from Saturday`s readings for the I-25 corridor. Winds will begin to weaken as upper high continues to build over the srn Rockies, and anticipate most areas won`t see speeds high enough to warrant a fire weather highlight, though hot and dry conditions will certainly persist. .LONG TERM...(Sunday night through Saturday) Issued at 244 PM MDT Sat Aug 17 2019 Not much difference between the ensembles and operational GFS through the extended period, with the ECMWF diverging in the later periods. Sunday night through Monday...high pressure is forecast to sit across the region with overall dry conditions expected prevail. High temperatures on Monday will continue to be hot with upper 90s to near 100 across the Plains. Tuesday through Thursday...high pressure is forecast to shift east into the Central Plains through the middle part of the week. Expect increasing moisture on Tuesday with energy moving northward out of the Desert Southwest by the afternoon. This will lead to scattered shower and thunderstorm activity across the region. Southwesterly flow may be strong enough for a few storms to move off the higher terrain into the Plains. Given the hot temperatures on Tuesday near 100 across the Plains, lightning and gusty outflow winds will be the primary storm threats. A cold front is forecast to arrive by Wednesday morning with cooler air and winds shifting more upslope across the lower levels. This will combine with energy lifting north out of the Desert Southwest to generate widespread shower and thunderstorm activity. This activity will spread east overnight across the Plains. Another upper disturbance will lift north out of the Desert Southwest on Thursday. This will lead to another round of widespread shower and thunderstorm activity. Afternoon highs both days will reach into the 80s to lower 90s. Burn scars will have to be monitored for flash flooding given the potential for thunderstorms to produce heavy rain. Friday into Saturday...high pressure will continue to sit over the Central Plains into the weekend, as an upper level trough moves into the Northern Rockies. Energy across the state will likely lead to at least scattered shower and thunderstorm activity. Increasing flow aloft will likely lead to mixing, drier conditions and warmer temperatures with 90s across the Plains. Mozley && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 244 PM MDT Sat Aug 17 2019 VFR conditions at all taf sites the next 24 hrs. Outflow from tsra over the high terrain north and west of KCOS may produce some gusty and erratic winds at the terminal until sunset, then winds diminish all terminals overnight. Little/no convection anywhere across the area on Sun, with lighter winds all terminals. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...LINE SHORT TERM...PETERSEN LONG TERM...MOZLEY AVIATION...PETERSEN
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Sunday night) Issued at 338 PM CDT Sat Aug 17 2019 This afternoon the region was wedged between surface low pressure along the east side of the Rockies and high pressure over the eastern U.S. As a result, prevailing southerly flow continued to support warm, moist-air advection with afternoon highs reaching into the upper 80s to around 90 degrees for much of the CWA, with the exception of far east central KS where lingering cloud cover from nearby showers has helped to hold temperatures in the low/mid 80s. With dewpoints reaching into at least the low 70s, decent destabilization has been occurring this afternoon. While the cap will continue to weaken into late this afternoon, latest short-range model soundings suggest we may not be able to completely eliminate the cap. As a result, the scattered showers and isolated storms over southeastern KS are looking to stay predominantly in that region and may potentially skim across east central KS into early evening. Bigger concern for thunderstorms will be late this evening through the overnight hours as another complex of storms looks to develop as a result of a mid-level embedded shortwave over southwest NE/northwest KS. As this complex of storms progresses eastward toward the CWA, the 35-45+kt LLJ should help to amplify storms late this evening and overnight. Model soundings show steep mid-level lapse rates with sufficient effective shear and instability to support strong to severe thunderstorms with the primary hazards being damaging winds, some large hail, and heavy rainfall. In fact, several runs of the HRRR have consistently been developing a bowing segment across the CWA, so damaging wind gusts of 60-70 mph certainly will be possible. While these storms may be more progressive compared to storms from the previous couple of nights, latest short-range model runs suggest that back-building storms will be possible as the mid-level shortwave continues to progress across the area with a strong LLJ still in place. As a result, expect some areas of heavy rainfall with widespread 1-2 inches and locally higher amounts of 2-3 inches possible. Considering how saturated soils are from thunderstorms over the last two nights, resulting in lowered flash flood guidance values, went ahead and issued a Flash Flood Watch for much of northeastern KS into portions of east central KS. Models show surface low pressure advancing eastward into the area, with an associated cold front extending into north central KS by Sunday morning. Some scattered showers and storms may continue to develop across portions of northeast and east central KS through the day as the front slowly progresses southeastward across the area. Depending upon how quickly it can exit the area, cannot rule out that enough destabilization can occur through the day to support a few strong to marginally severe storms late afternoon into the early evening, but otherwise expect conditions to gradually dry out Sunday night as the front shifts east of the area. Even with this passing system, dewpoints in the low/mid 70s will still remain with highs reaching into the mid 80s in north central KS to the low 90s over east central KS. As a result, afternoon heat index values in the 100- 105 degree range will be possible in east central KS. .LONG TERM...(Monday through Saturday) Issued at 338 PM CDT Sat Aug 17 2019 The overall weather pattern by Monday should feature a building upper ridge into the central Plains which will set the stage for heat indices easily reach or exceeding 100 degrees Monday through Tuesday. By Tuesday night a deep upper trough will slide into the Great Lakes pushing a cold front south into the state which will likely get hung up across the state. NW flow aloft along with the front and LLJ appear to set the stage for another overnight complex of storms Tues night into Weds and perhaps again Weds night into Thurs as nightly low level forcing of WAA and convergence from LLJ will continue to plague us. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 639 PM CDT Sat Aug 17 2019 A line of strong thunderstorms will move east across the terminals around 6Z SUN at KMHK and around 7Z to 8Z SUN at KTOP and KFOE. There is a chance this line may contain severe wind gusts over 50 KTS primarily from the west behind the gust front. After the convective line passes east of the terminals after 9Z, there may be some trailing stratiform rain and elevated thunderstorms into the mid morning hours. As the southwesterly low-level jet increases to 40 to 50 KTS about 1500 feet above the surface after 3Z SUN, the low-level wind shear will increase to 30 to 40 KTS. The Low-level wind shear will diminish after 12Z SUN. && .TOP WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from 10 PM CDT this evening through Sunday morning for KSZ009>012-021>024-026-036-038>040-055-056-059. && $$ SHORT TERM...Hennecke LONG TERM...Omitt AVIATION...Gargan