Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/28/21

Area Forecast Discussion
National Weather Service Denver/Boulder CO
816 PM MDT Fri Aug 27 2021 .UPDATE... Issued at 814 PM MDT Fri Aug 27 2021 Position of weak upper level jet, in WSW flow aloft, combined with some influx of tropical moisture, was allowing for widely sct weak tstms this evening. In addition a Denver cyclone was enhancing low level convergence, east of DIA, with a developing line of storms. Latest HRRR wants to consolidate this activity, into a small cluster of storms, which will move across the far nern plains by 08Z. Based on current radar trends this trend is probably going to be correct. && .SHORT TERM...(This evening through Saturday) Issued at 232 PM MDT Fri Aug 27 2021 A closed low over Canada has a trailing trough with with some weak perturbations in the flow pushing across Colorado late tonight and Saturday. Conditions will clear out overnight after a few isolated showers and storms move through during the evening hours before a weak surge pushes south Saturday morning. Main impacts from any storms that form will be gusty winds up to 40 mph with brief light rain. The surge that pushes through early Saturday looks to be pretty moisture starved but it will bring a slightly cooler airmass and keep high temperatures in the upper 80s to lower 90s for the plains. This cooler boundary layer will also help to cap the atmosphere for Saturday and keep storms at bay and conditions dry. Will maintain some low POP chances over the southern mountains and foothills for late Saturday for isolated storms that could form over southern portions of the state and push northeast. .LONG TERM...(Saturday night through Friday) Issued at 256 PM MDT Fri Aug 27 2021 Saturday night features flat upper ridging for the CWA with an upper trough moving eastward to the north of Colorado. This trough will usher in a cold front Saturday evening. Flat upper ridging remains in place with pretty weak west-southwesterly flow aloft through Monday night. In the low levels, winds will keep an easterly component to them much of Sunday. Normal diurnal wind patterns are expected Sunday night through Monday night. The QG Omega fields show benign synoptic scale energy all five periods. Moisture is pretty sparse over the mountains through the periods. There is some low level moisture with the upslope over the plains Saturday night and Sunday. However, instability is lacking with a strong cap in place. For Monday, there is substantial warming and there is a notable cap around 500 mb. Not to excited for pops Saturday night through Monday night. For temperatures, Sunday`s highs are 3-6 C cooler than Saturday`s. Monday`s readings warm-up 5-7 C. For the later days, Tuesday through Friday, models have the upper ridge push east and southeast of the CWA through periods, with a significant upper trough over the western U.S. coast Wednesday through Friday. The flow increases a bit and becomes more southwesterly by mid week. Moisture increases a bit Tuesday into early Wednesday, then is it increases significantly for Wednesday through Friday. Tuesday looks pretty hot as far a temperatures go, then it cools down to around seasonal readings for Wednesday through Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 814 PM MDT Fri Aug 27 2021 A Denver cyclone was in place with weak convection to the east of DIA. There were also a few weak storms to the west as well. Have put in VCTS thru 04z in case one develops near the airport. Winds were northeast due to the circulation around the cyclone but still expect them to go more southeast to south after 04z. && .HYDROLOGY... Issued at 232 PM MDT Fri Aug 27 2021 Drier conditions today compared to yesterday with just a few high based storms possible. Dry for Saturday with no flood threat expected for burn areas. There isn`t a threat of flash flooding Saturday night through Monday night. With the increasing moisture from Tuesday through Friday, the threat of flash flooding will increase, especially over the burn areas. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...RPK SHORT TERM...Bowen LONG TERM....RJK AVIATION...RPK HYDROLOGY....Bowen/RJK
Area Forecast Discussion
National Weather Service Grand Forks ND
958 PM CDT Fri Aug 27 2021 .UPDATE... Issued at 958 PM CDT Fri Aug 27 2021 Upstream thunderstorms/showers decreased in coverage as they moved towards our CWA this evening, however a few may hold together through late evening. There looks lot be little in the way of organized forcing overnight, but convergence along surface trough and WAA aloft may be enough to support additional shower or thunderstorm development as RAP still shows potential for 1000-1500 J/KG elevated CAPE axis overnight. However, there really isn`t a noticeable LLJ and latest CAMs have backed off on coverage/potential through 03Z. Better potential tonight will be as clusters of showers/storms (currently in northwest SD) move across the souther RRV. Patchy fog is being reported over parts of our area with 3-6sm vis and Td depressions are approaching zero across the region. Due to recent rains and light southeast flow BL saturation may occur and short range guidance is showing potential for fog. I made adjustments to timing of PoPs for the overnight and added fog mention based on these trends. UPDATE Issued at 635 PM CDT Fri Aug 27 2021 Showers are still lingering over our eastern CWA, but are transitioning out in line with CAMs consensus. There should be a lull in precipitation, the rest of the evening and there will be at least some potential for smoke to advect back into the region behind the departing showers. There is till a signal for possible nighttime convection along an elevated CAPE axis/prefrontal trough around midnight tonight into the early morning hours, however there is very little consensus with a large spread in CAMs regarding evolution or even development (more members show no precip tonight than do show it). If something per to develop we still could be in line for a few strong to severe elevated storms as effect shear will be very high and elevated instability around 1500 J/KG. Worth monitoring, but confidence still isn`t high (will monitor trends). && .SHORT TERM...(This evening through Saturday night) Issued at 317 PM CDT Fri Aug 27 2021 Showers continue pushing northward this afternoon, with much of the activity now in northwestern Minnesota. Quiet weather is expected through the remainder of the afternoon as this exits the region to the northeast. Through the early overnight period, scattered showers develop through around midnight. Looking at CAMs, the majority of guidance prevents the development of severe thunderstorms; however, a handful of high resolution ensemble members bring a rather strong line of thunderstorms through the area during the pre-dawn hours Saturday morning. MUCAPE will be in the 1000 to 1500 J/Kg range, with good 0-6 km speed shear upwards of 50 kt. Impacts would be possible if this line strengthens along the cold front, with damaging wind gusts being the primary risk. Through the remainder of the day on Saturday, look for scattered shower activity across portions of the region in the post-frontal environment. Highs will climb into the lower to middle 70s. Showers gradually work to the east, with clearing expected heading into Saturday night. .LONG TERM...(Sunday through Friday) Issued at 317 PM CDT Fri Aug 27 2021 During the long term the pattern aloft makes some noticeable changes that affect the propagation of troughs for the Northern Plains. Through the weekend and into early next week, a ridge begins to develop in the southern United States providing a SW return of moisture from the SW. This helps provide decent monsoonal moisture to the area and the translation of a trough into the region. Chances for thunderstorms increase middle of the week as a trough moves in from the SW. During the end of the week the pattern turns more NW cutting moisture off from the south and amplifying a potential ridge back into the SW United States. Sunday and onward... Dry and calm conditions end the weekend, with a zonal flow aloft helping keep temperatures cooler across the region. Zonal flow continues into Monday, with chances for thunderstorms during the afternoon but on an isolated basis as a weak short wave moves in from the Pacific NW. Isolated storms are possible Tuesday afternoon before the flow aloft turns SW allowing for more moisture and better signal of thunderstorms in the Northern Plains. Thunderstorms are possible across the area Wednesday into Thursday, with a deepening trough out west. Latest ensemble runs indicate monsoonal moisture and part Gulf moisture interacting with the system over the plains. Instability between ensembles have varied, with low chances of CAPE exceeding 2000 j/kg. Majority of ensembles have the probabilities of CAPE exceeding 1000 j/kg ranging from 40- 60%. Shear is rather weak in the lower levels compared to sfc to 8km shear. This could inhibit some development of thunderstorms across the region. Uncertainty continues to lie in the timing of the system and how much moisture it can tap into. Ensembles continue to show the system affecting portions of western ND during the afternoon and evening, with limited instability and daytime heating in the Red River Valley. This would lower the risk of any stronger storms in the region. Other scenarios show the trough moving faster along allowing for eastern ND and western MN to tap into the heating and instability during the afternoon. Moisture shows a surge from the southwest, but how much there actually is is dependent on how amplified the ridge may be in the southern United States. Probabilities of precipitation exceeding 0.5 inches ranges from 30- 50% across the area, with the best chance closer to the international border. After the system moves out further chances for storms are possible to close out the work week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 635 PM CDT Fri Aug 27 2021 Variable flight conditions as a result of lingering stratus across eastern ND and northwest MN, while showers are exiting northwest MN early in the TAF period. There are clearing areas with VFR conditions, but these are not likely to prevail as stratus is shown by guidance to fill back in and IFR returns overnight into Friday morning. Additional showers or thunderstorms (some possibly severe) can`t be ruled out tonight, but better chances are across southeast ND and west central MN Saturday. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...DJR SHORT TERM...Lynch LONG TERM...Spender AVIATION...DJR
Area Forecast Discussion
National Weather Service Grand Junction CO
826 PM MDT Fri Aug 27 2021 .UPDATE... Issued at 826 PM MDT Fri Aug 27 2021 Latest observations in northwest Colorado indicate that winds are diminishing and relative humidities are increasing as surface inversions take hold. Thus, have allowed the ongoing Red Flag Warning to expire as scheduled. && .SHORT TERM...(Tonight through Saturday night) Issued at 255 PM MDT Fri Aug 27 2021 A few isolated thunderstorms have blossomed along the southern foothills of the San Juans early this afternoon, favoring areas with higher PWAT values and within the bullseye of elevated SBCAPE. Slow moving storms will move off higher terrain to the east-northeast, decreasing in coverage by 6 PM MDT. Main impacts from said storms will be frequent lightning and gusty outflow winds. PWAT values decrease as you move north across the Western Slope, dropping from 0.8 inches to 0.4 over northeast Utah and northwest Colorado. A dry slot, most noticeable at mid levels, will support a deep mixing layer up to nearly 500 mb this afternoon. As a result, gusty afternoon winds, 15 to 20 mph, are likely across much of the forecast area. Meanwhile, an upper level jet, rounding the belly of a low pressure system to the north, has tightened the pressure gradient over northeast Utah and northwest Colorado. As this piece of energy rotates across the Northern Rockies, dry conditions and enhanced winds will generate critical fire weather conditions over regions with susceptible fuels (i.e. northwest Colorado). Winds will begin to relax in the wake of the upper level jet this evening, and more-so once the surface decouples after sunset. Therefore, the current fire highlight remains untouched with this forecast package, dropping off at 8 PM MDT. Another lobe of PV and its associated jet maxima roll through Idaho and into western Wyoming by tomorrow morning. Though this system slides to our north, the northwesterly winds upstream will start to push a rather thick plume of smoke from NorCal fires back into our CWA. East central to northeast Utah and northwest Colorado will see impacts first, early Saturday morning with the plume extending southward throughout the day. Patchy smoke could extend down to the Four Corners region, however higher concentrations of smoke will likely hover along and north of the I-70 corridor. Unfortunately, winds aloft shift to zonal flow by Saturday afternoon, maintaining the swath of poorer air quality overhead. Temperatures will remain a few degrees over season normals through the short term. However, if the HRRR smoke Vertically Integrated Smoke Column comes to fruition, max temps across the north may be a little too aggressive. .LONG TERM...(Sunday through Friday) Issued at 255 PM MDT Fri Aug 27 2021 A quiet start to the long term period will end on an active note as the remnants of Tropical Storm Nora trek across the Desert Southwest. Sunday will see quasi-zonal flow set up overhead resulting in another warm, quiet day across eastern Utah and western Colorado. A ridge of high pressure will build to our south on Monday and gradually expand on Tuesday. Meanwhile, another upper level trough will dig into the Pacific Northwest while the decaying Ida continues to progress inland across the southeastern United States. As a result of this synoptic shift, expect an increase in southwest flow aloft with subtropical moisture streaming north on the backside of the ridge. Early on we will see an increase in mid and high level clouds over our forecast area before an uptick in shower and thunderstorm coverage looks possible as early as Tuesday afternoon and evening. This unsettled flow and increase in convection will continue on Wednesday as Nora treks along the Baja coast. The aforementioned Pacific trough will continue to elongate along the western CONUS, shifting the ridge further east towards the Southern Plains on Thursday. In response, the remnants of Nora will continue to progress further inland across the southwestern states. As mentioned, this additional swath of moisture could cause PWATs to exceed 1 inch for a good portion of the area and possibly reach 1.5 inches for some locations. Though things could change, confidence is increasing in the potential for widespread moderate to heavy rainfall over the course of mid to late next week. We will continue to remain vigilant over the coming days, most notably in regards to how this increased convection could affect the high-impact Grizzly Creek burn scar along I-70. Be sure to stay tuned to the latest forecast! && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 537 PM MDT Fri Aug 27 2021 A few showers and storms continue over the San Juans but they will quickly dissipate in the next hour or so. No concerns for TAF sites. Few to scattered skies will become clear overnight as smoke starts to filter back into the area. Do not anticipate any restrictions to visibility but there will be smoke across the area. Expect a few gusty surface winds tomorrow afternoon reaching 20 to 25kts from the west-northwest. VFR conditions will continue. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ UPDATE...MDM SHORT TERM...ERW LONG TERM...MMS AVIATION...TGR
Area Forecast Discussion
National Weather Service Goodland KS
535 PM MDT Fri Aug 27 2021 .SHORT TERM...(This evening through Sunday night) Issued at 309 PM MDT Fri Aug 27 2021 Across the region this afternoon, most of the area is under sunny skies except for east/southeast locales as they still fall under the influence of a trough that has been meandering over the CWA all day. Temps are ranging in the 90s area-wide with winds mostly variable, but a few locales are seeing gusts to 20 mph at times. For the remainder of the afternoon, the wx focus will be on the remnants of the trough that has been meandering about the CWA all day. Latest analysis has shown this to shift a bit west this afternoon. Areas of cumulus continue to pop up along and east of this with some shower activity showing up. The latest HRRR is showing a few hours of some activity, with a northeast movement should anything get going and persist. Any storms will have sub severe gust potential along with hail and locally heavy rainfall. Going into Saturday, the focus shifts to an approaching frontal boundary associated with a low/trough set to move off the Rockies during the afternoon hrs. Model timing of this system will affect areal coverage of any potential strong to severe storms that do develop. SPC has almost all of the CWA under a Marginal risk for wind/hail. The track of the system puts the CWA on the tail-end of best instability, but daytime heating ahead of the arrival will trigger storms. Model DCape values will peak in the 1500-2000 j/kg range in the east/southeast around 18z. Threats will be mainly wind with 60-70 mph possible, but hail around an inch is also possible. Convection is expected to wane from west to east into the evening hours as high pressure builds across the region overnight. Persistent low clouds are probable going into Sunday morning due to the positioning of the ridge axis and exiting front. Cooler air persists thru the day as the ridge transitions east of the CWA late in the day into the overnight hours. For temps, highs on Saturday will be similar to this afternoon. 90s area-wide expected. Warmest locales along/east of Highway 25. Sunday will have a slightly cooler airmass with 80s expected. Overnight lows tonight will be highly dependent on any lingering clouds from any precipitation received. A wide range from the lower 60s west to around 70F east is expected. For Saturday night, upper 50s west to upper 60s east. And for Sunday night, upper 50s west to mid 60s east. Concerns for high heat indices will only focus on the Saturday timeframe. areas west of Highway 25 will see 90s, while along/east of there will have upper 90s to even low 100s in spots especially east of Highway 83. .LONG TERM...(Monday through Friday) Issued at 317 PM MDT Fri Aug 27 2021 At the start of the long-term period, the CWA lies underneath an upper air ridge over the central CONUS which expects to be between a trough in the east and a trough building in the Pacific Northwest. This pattern aloft gives the flow over the CWA a westerly direction to begin that changes to northwesterly by the evening as the troughs squeeze the ridge. This trough-ridge-trough pattern continues going into Tuesday with the western trough moving a bit eastward. The eastward trough progression appears to continue into Wednesday and begins to push the ridge to the east with the base of the trough beginning to strengthen in the northwestern CONUS. By Thursday morning, the flow over the CWA looks to turn southwesterly as the CWA is underneath the inflection point between the upper air trough to the west and the upper air ridge to the east. This northwesterly flow continues going into Friday though the ECMWF shows the trough beginning to progress eastward Friday afternoon with the GFS starting the trough progression late Friday. The situation will be monitored to see if better agreement will come about in future runs. At the surface, the CWA looks to start with dry conditions followed by some chances for precipitation through the end. Monday and Tuesday look to have minimal chances of precipitation with possible near-critical fire weather conditions seen on Tuesday for areas along and west of the CO border during the afternoon. Minimum RH values as low as 15% are seen in these areas, but the below criteria maximum wind gust values continue to be the limiting factor. Chances for precipitation return Wednesday morning as models show a possible surface trough setting up in eastern CO along with increased moisture coming in from the south at 850mb. A surface low pressure system appears to develop in eastern CO on Thursday that moves slowly northeastward through the CWA on Friday. This system looks to show early signs for precipitation chances on both days, but models show differences in how it plays out and will need to be monitored in the upcoming runs. The Tri-State area should see high temperatures on Monday between the lower and upper 90s. On Tuesday and Wednesday, daytime highs look to be between the middle to upper 90s followed by Thursday and Friday seeing highs in the middle 80s to lower 90s. Tri-State area overnight lows for Monday and Thursday look to stay in the upper 50s to middle 60s with lows on Tuesday and Wednesday in the lower to middle 60s. Friday`s overnight lows expect to be the coolest with lows in the upper 50s to lower 60s. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 529 PM MDT Fri Aug 27 2021 VFR conditions are expected through the forecast period at both terminals. Winds become southerly this evening around 10-15kts at KGLD with a period of low-level wind shear possible from 05-09Z. Southerly winds persist through mid-morning where they become south-southwesterly around 13-17kts with gusts to 21kts. At KMCK terminal, southerly winds prevail through the TAF period with winds remaining generally under 12kts through 17Z. Winds are expected to increase at that time as a boundary moves through the area. A period of low-level wind shear may be possible from 05-12Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...JN LONG TERM...076 AVIATION...AW
Area Forecast Discussion
National Weather Service Green Bay WI
610 PM CDT Fri Aug 27 2021 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Saturday Issued at 238 PM CDT Fri Aug 27 2021 Cloudy skies along with showers continued this afternoon. A few thunderstorms were noted across east-central Wisconsin. The rain and clouds kept temperatures down, ranging from the lower to middle 60s north to the lower to middle 70s south. A warm front south of the area will be the focus for showers and thunderstorms through tonight. The combination of 850mb warm advection, along with a low level jet cranking up will bring rounds of showers and thunderstorms to the area. Convection in response to the low level jet is expected to develop across Minnesota and western Wisconsin and then move east across the area later this evening and overnight. Really thought long and hard about a Flash Flood Watch for portions of central and northeast Wisconsin, especially in areas that saw heavy rain last night. Based on the regional radar trends, current thinking is the heavy rain axis will fall from central Wisconsin northeast into Marinette, Oconto and Door County. The meso models, especially the HRRR continue to move around the axis of heavy rain thus the confidence was too low to issue a Flash Flood Watch. Do believe there will be a band of rain with rainfall totals of at least 1 to 2 inches in the above mentioned area. As the complex rolls through the area, some of the storms could become strong or severe with damaging winds as the primary risk. Could not rule out an isolated large hail event. The warm front will lift north into northern Wisconsin on Saturday. The area should be capped, thus the risk of thunderstorms through mid afternoon will be very low. By late afternoon, the cap may erode enough for thunderstorms to develop, especially across the north where there is 2,000 to 3,000 J/KG of CAPE. If storms do develop, they will likely become strong or severe with strong winds and possibly large hail. Highs will be in the 80s to around 90. The combination of the heat and humidity will cause the heat index value to climb into the middle 90s to around 100F Saturday afternoon. .LONG TERM...Saturday Night Through Friday Issued at 238 PM CDT Fri Aug 27 2021 Severe weather and heavy rainfall potential Sunday evening, and a continued threat of severe storms Sunday afternoon, will be the main forecast concerns in the extended forecast. A very unstable air mass will reside over the forecast Saturday evening, with CAPE of 1500-2500 j/kg. The main focus for severe weather and heavy rainfall should be over northern WI, where a 30 to 40 knot LLJ will intersect a surface warm front. Deep layer shear of 35 to 40 knots will be supportive of organized convection, including supercells. SPC has expanded the SLGT Risk over most of northern WI, and this looks reasonable. Models show a decent signal for heavy rainfall over northwest and parts of north central WI, and this is where the core of the LLJ takes aim. Not expecting much more than an urban flooding concern in north central WI, as they have not received much rain in the past couple weeks, and much of the region has sandy soils. A cold front will sweep across the region on Sunday, accompanied by a short-wave trough. Instability is expected to increase over eastern WI by midday, with CAPE around 1500 j/kg. Scattered strong to severe storms will be possible in the afternoon over northeast and east central WI. SPC has outlooked this area in a Marginal Risk of severe storms. Generally quiet weather is expected from Sunday night through the middle of the next work week, as weak high pressure remains over the region. Temperature should return to near-normal during this period, along with more comfortable humidity levels. As the high pressure shifts east of the region, return flow will bring a chance of showers and storms Wednesday night into Thursday. A cold frontal passage will continue the chance of showers and storms Thursday night into Friday. && .AVIATION...for 00Z TAF Issuance Issued at 609 PM CDT Fri Aug 27 2021 Several rounds of showers and thunderstorms are expected this evening into Saturday morning. Some of the storms tonight could produce strong winds, hail and torrential rainfall. Conditions will vary widely due to convection and lingering low stratus clouds. Expect a mix of IFR/MVFR CIGS across central and north- central with some VFR/MVFR possible in east-central Wisconsin. Showers and thunderstorms will lower conditions as they pass through. Easterly winds will gradually veer to the south late tonight into Saturday morning. Southerly winds could gust to around 25 knots Saturday afternoon. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....Eckberg LONG TERM......Kieckbusch AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Grand Rapids MI
1034 PM EDT Fri Aug 27 2021 LATEST UPDATE... Update .SYNOPSIS... Issued at 316 PM EDT Fri Aug 27 2021 - Chance of storms north tonight - Hot Saturday - Better chance of storms Sunday, possibly strong - Cooler and much less humid air by mid week && .UPDATE... Issued at 1033 PM EDT Fri Aug 27 2021 Our strong to severe thunderstorms episode between Baldwin and Big Rapids has come to an end. However as typical of a slow moving warm front, every mid-level wave creates more thunderstorms. There are currently two more complexes of thunderstorms, one over Iowa and the other Wisconsin that are heading toward the northern 1/3 of Michigan between now an sunrise. The moisture transport vectors suggest the storms will largely stay north of our CWA tonight. That idea is also supported by HRRR and RAP models. However the glitch is we have the NAM suggesting the warn front stalls overnight and we have surface east winds down to I-94. If that were to really happen, we may see convection develop after 3 am near US-131 and last until after sunrise. The HRRR however turns the east winds to the south southwest south of Route 20 by 3 am. If that happens, the convection would stay farther north. I am going with that later idea and believing the warm front is strong enough to keep the convection farther north tonight. Given the precipitable water is near 2 inches currently, any storm could produce locally heavy rain as we have seen for at least 5 days in a row now. That more than anything would likely be our biggest overnight impacts. && .DISCUSSION...(This evening through next Friday) Issued at 316 PM EDT Fri Aug 27 2021 -- Chance of storms north tonight -- A warm front lifted through the cwa today and is now just north of the cwa. Ongoing convection has been mostly over Wisconsin, but one small bowing segment crossed over the lake and is currently weakening. Mesoanalysis shows 35-40kts of shear and 1500+ j/kg mlcape. We`ll continue to monitor the progress of this storm. CAMs don`t show much pcpn the remainder of this afternoon through the evening. After that, another are of storms may try to make a run at the northern cwa after midnight. The HRRR/NAMNest/HREF show a line of storms moving across northern Lake MI and then diminishing as they get to the east side of the lake. The LLJ will remain over Wisconsin tonight so once the storms move out of that favorable environment, they should diminish. Overnight timing of the pcpn also should lead to less instability so we don`t anticipate anything severe overnight. -- Hot Saturday -- We`ll remain in the soupy airmass Saturday. A decent amount of sunshine coupled with dewpoints in the lower 70s should push apparent temperatures to around 100. Because of that we issued a Heat Advisory from 18z-00z. The stagnant airmass has also prompted the Michigan Department of Environment, Great Lakes, and Energy to issue an Air Quality Alert for Saturday. -- Better chance of storms Sunday, possibly strong -- A cold front is expected to move across Lower Michigan Sunday afternoon. Ahead of it, models indicate we`ll have sbcape around 2k j/kg along with abundant low level moisture. It`s worth noting though, that the short wave driving the front moves from Wisconsin northeast across Lake Superior, so dynamical support may wane a bit. However, the lift from the front should be enough to fire some storms. I`d expect the strongest storms to be over the northern half of the cwa. A Slight Risk of severe storms was noted by SPC north of I-94 Sunday. -- Cooler and much less humid air by mid week -- Behind the cold front, a little bit of an upper trough develops over the Great Lakes early next week. This trough may be enhanced by the passage of the remnants of Ida as it moves across the Ohio/Tennessee Valleys. This will help to pull in some cooler and much less humid air. Highs in the 70s and dewpoints in the 50s are expected. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 709 PM EDT Fri Aug 27 2021 At this point it seems to me VFR with scattered clouds is the best forecast for our TAF sites through Saturday evening. Some light fog is possible toward sunrise, I put 4-5SM BR for that. There should be enough wind in the boundary layer to keep any thicker fog from developing overnight. Numerous waves of thunderstorms will continue to track eastward (more or less) along the warm front tonight into Saturday but with the front slowly lifting north, it would seem rather unlikely any storms could get as far south as our TAF sites. Saturday should be mostly clear with a few cumulus clouds that lack any serious vertical development. The next threat for storms would be with the cold front later Sunday. && .MARINE... Issued at 316 PM EDT Fri Aug 27 2021 A warm front is slowly moving north across the northern nearshore zones. Winds are generally light from the south behind it. Other than the potential for a few storms late tonight north of Whitehall, no marine issues are expected until Sunday. At that point, southerly flow will increase ahead of a cold front and waves may bump up to small craft criteria north of Whitehall by Sunday morning. A Small Craft Advisory may be needed then. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Heat Advisory from 2 PM to 8 PM EDT Saturday for MIZ037>040- 043>046-050>052-056>059-064>067-071>074. LM...None. && $$ UPDATE...WDM SYNOPSIS...04 DISCUSSION...04 AVIATION...WDM MARINE...04
Area Forecast Discussion
National Weather Service Huntsville AL
856 PM CDT Fri Aug 27 2021 .NEAR TERM...(Tonight) Issued at 856 PM CDT Fri Aug 27 2021 Scattered thunderstorms are still ongoing at this relatively late hour, with the most active storms focused SE of the HUN CWFA entering Etowah and Cherokee Counties. 01Z mesoanalysis, 00Z BMX sounding, and model soundings all suggest that the nocturnal inversion will be rather slow to develop this evening, so storms may persist a little later than usual. Otherwise, scattered cloud cover is creating a broad temperature range across the area, with Tupelo having reported 87 at 01Z, and Decatur 73 at the same time. The forecast has been updated a few times already this evening to reflect ongoing radar trends, and one more update is needed to account for the storms approaching from the SE. As mentioned earlier, CAM trends and operational model soundings all suggest that these storms may hang on a little longer than usual, so the forecast will prolong PoPs into the late evening hours over eastern areas. It`s entirely possible that this forecast is too conservative, though, as the 00Z HRRR (which isn`t resolving the approaching cluster specifically) brings isolated cells all the way into southern TN before dissipating them around 06Z. The rest of the forecast is in good shape, with low temperatures expected to fall only into the mid 70s for much of the area. .SHORT TERM...(Saturday through Sunday) Issued at 312 PM CDT Fri Aug 27 2021 Chances for isolated to scattered thunderstorms will increase over the weekend, especially on Sunday as an upper ridge continues to shift west through the Carolinas and east/southeasterly flow results in gradual moisture advection. These storms will be largely diurnally driven as the lack of any real forcing mechanism limits coverage and longevity. Will see little change in temperatures over the weekend, as highs range from the upper 80s/lower 90s and overnight lows remain in the low to mid 70s. .LONG TERM...(Sunday night through Thursday) Issued at 312 PM CDT Fri Aug 27 2021 All eyes will be focused on what is now Hurricane Ida, which is expected to intensify into a major hurricane by landfall along the southeast LA coast on Sunday night. Our impacts will start to ramp up late in the day on Monday, as cloud cover and rainfall from the outer feeder bands work their way closer to the Valley. This will moderate temperatures a bit on Monday, keeping highs in the mid to upper 80s. With the current forecast track, our main window for impacts will come from early Tuesday morning through Tuesday evening. It is important to keep in mind that even minor changes in the forecast track can result in significant forecast changes as far as rainfall and severe weather are concerned. For now, it looks like our main impacts will come from flooding and a few tropical tornadoes also look possible. Will have to keep our eyes on this system closely, as the track and intensity will likely change at least some over the weekend. Do not want to get too specific as far as rainfall amounts just yet, but want those in the Tennessee Valley to be prepared for potential flooding and review their severe/tornado safety plans. Ida should exit the area by late Wednesday, where it looks like a cooler, slightly more dry pattern will follow toward the latter half of the week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 639 PM CDT Fri Aug 27 2021 Showers and perhaps a few embedded storms are lined up to impact KMSL and perhaps brush KHSV between now and 01Z; for right now, TAFs include VCTS with a short TEMPO group, but this may be adjusted and amended further based on radar/lightning trends. Once these storms weaken and dissipate, VFR conditions should mostly prevail thru 00Z/29. Scattered mid-level clouds should reduce the fog threat, though brief patchy fog can`t be ruled out especially with storms this evening. Scattered storms will develop again tomorrow afternoon. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...BCC SHORT TERM...25 LONG TERM...25 AVIATION...BCC For more information please visit our website at
Area Forecast Discussion
National Weather Service Elko NV
246 PM PDT Fri Aug 27 2021 .SYNOPSIS...Dry weather with hazy skies from California wildfires prevail through the weekend. && .SHORT TERM...Tonight through Sunday evening. Northern Nevada is on the southern fringe of a trough axis crossing the northern Rockies. This changes the wind flow to west northwest flow. This subtle change in wind direction may provide brief respite to the smoky skies over northern Nevada. The HRRR smoke model shows improving visibility tonight, primarily north of I80. As the trough moves farther downstream, gradient winds return to a westerly component and the smoke may return to northern Nevada Saturday afternoon, and likely continuing into Sunday. Breezes increase to the 20-25 mph range Sunday afternoon as the next short wave approaches the Pacific Northwest coast. With rising heights, temperatures trend warmer the next two days. .LONG TERM...Sunday night through next Friday Hazy and smoky conditions are likely to continue through next week. With an upper trough still expected to dig south from the Pacific Northwest beginning early in the week, high temps are to gradually begin cooling Monday. Expect high temps mostly in the mid to upper 80s by mid-week. Overnight low temps look to reside in the low 50s for most Sunday night before also creeping cooler with a return to mid to upper 40s by mid-week. Mostly dry thunderstorms with only a few wet storms possibly mixed in continues to be expected for the Tuesday to Thursday time frame with slightly greater activity likely on Wednesday. This will affect the southeast portion of the forecast area. Be aware that there is still some uncertainty in the amounts of moisture expected to reach central/eastern Nevada. This is based on the additional factor of how much residual tropical moisture may be pulled northward from the potential remnants of Nora. Confidence remains relatively low at this time. && .AVIATION... Visibility may improve to 10+ statute miles this evening at KWMC, KBAM and KEKO as surface winds shift from the northeast. VFR conditions are expected to prevail, although brief periods of 5SM/6SM may occur in smoke or haze at any given time. && .FIRE WEATHER... Westerly gradient flow increases early next week with a trough axis positioned along the Pacific Northwest coast. On Sunday, appears winds stay below critical thresholds. Northwest Nevada, particularly zone 437 may exceed the wind threshold on Monday and Tuesday with local gusts reaching 30 mph. With the trough axis moving inland, these afternoon wind gusts may expand its territory and include all of northern Nevada. Afternoon humidities stay dry with values around 10% (or less). && .LKN WATCHES/WARNINGS/ADVISORIES... None. && $$ 88/92/88/88
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
922 PM CDT Fri Aug 27 2021 .UPDATE... 922 PM CDT No significant changes to going forecast tonight. Thunderstorm potential continues to look fairly low across the local area tonight, and while perhaps a non-zero chance far northwest toward morning, will maintain a dry forecast through the night. Evening surface analysis depicts a warm front stretching from low pressure over the Black Hills region, eastward along the IA/MN border and into southern WI. Low level air mass south of this boundary remains very warm/humid, though with some drier mid-level air as noted in DVN`s 00Z RAOB. 35 kt low level jet was evident from southwest IA into western WI, coincident with a narrow axis of somewhat deeper moisture. Focus for evening convection has been on the nose of the low level jet and along/north-northeast of the warm front across northeast IA/southeast MN and parts of WI. Strong storm over Grant county in southwest WI is expected to weaken as it continues to track slowly east-southeast out of the better low level jet winds and into the slightly drier mid-level environment across southern WI/northwest IL. While not completely out of the question some remnant could approach the far northwest part of the cwa toward midnight, guidance trends continue to focus best continued convective potential to remain across the IA/MN border and into western WI within the low level jet axis. New 00Z 3 km WRF and 01Z HRRR runs suggest there may be an eventual southeastward sag of this activity as a consolidated cold pool forms later tonight, though indicate weakening/dissipation of updrafts along the outflow as it moves into northwest IL toward sunrise. Based on these observational and recent CAM trends, will maintain dry forecast at this time. Otherwise, a warm and humid night is in store with temps in the 70s. Other than a few minor tweaks to hourly evening temps, no significant changes made to going forecast which appears to be in good shape. Ratzer && .SHORT TERM... 305 PM CDT Through Saturday night... Very warm and humid conditions will continue across the area through Sunday. Similar to today, temperatures both Saturday and Sunday afternoons will top out around, or just above, the 90 degree mark. This heat, combined with oppressive surface dewpoints mid 70s, will result in heat indices topping out in the 100 to 105 degree range, especially for Saturday. While a heat advisory is not currently anticipated (local criteria is a heat index of 105+), it will definitely be a uncomfortable day to be outside in the sun. Thunderstorm chances tonight and on Saturday afternoon remain low, but not zero. Tonight we will have to keep an eye on convective trends to our northwest across northern IA and southern MN. This activity could try to push an outflow boundary southward over southern WI tonight. If it does so, some storms could accompany this outflow boundary, but the better chances for this continues to be north of the area in WI. I did maintain some slight chance pops for storms late tonight, mainly near the WI state line. Otherwise, it appears most areas will remain precipitation free tonight. We will then have another slight chance for a few isolated storms during peak heating Saturday afternoon, similar to what is going on this afternoon. However, a majority of the area is likely to remain dry. By far our best chance for showers and thunderstorms this weekend will be Sunday afternoon and evening as a surface cold front begins to shift into the area. It appears this front will move across northern IL during the evening hours of Sunday, and this is likely to be the focal point for scattered strong thunderstorms. Strong gusty winds and the threat for heavy rainfall will be the primary hazards associated with these storms late Sunday. KJB && .LONG TERM... 310 PM CDT Monday through Friday... Confidence is fairly high in the front stalling by Monday in a west-to-east nature somewhere within the Lower Great Lakes to Ohio Valley region. This slowness and eventual stalling is aided by the likely landfalling of tropical system Ida along the Gulf Shore and progressing northward (see official NHC forecast). There may be somewhere north of the hurricane on/near Tuesday that could see some interaction of the tropical system`s high moisture and the front, but at this distance that is an extremely low confidence target, and only a handful of 00Z GEFS and ECE ensemble members show a swath of higher precip north toward central Illinois and central Indiana, and a majority of those are south of the CWA. High pressure centered over the northern Lakes does look to expand its influence southward into the CWA during midweek, with northeast winds prevailing. Highs in lakeside counties look to be shy of 80 for a couple days. The northeast winds may be enough to bring waves to around a 4 ft average and present a heightened risk of dangerous swimming conditions. MTF && .AVIATION... For the 00Z TAFs... Tonight, south winds will prevail with mostly clear skies. Winds will become southwesterly after daybreak and gust 15-20 kt during the late morning and afternoon hours. A spotty cumulus deck rooted near 4000 feet will develop by early afternoon and fade toward sunset. While no precipitation is expected through the TAF period, a very small (<10%) possibility exists for thunderstorms ongoing in northeastern Iowa to develop a cold pool and track east-southeast toward the Illinois/Wisconsin state line during the predawn hours of Friday. The most likely scenario, by far, is for all convection to remain well to the northwest of all terminals tonight. Borchardt && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Lubbock TX
615 PM CDT Fri Aug 27 2021 .AVIATION... VFR until further notice. Check density altitude. Sincavage && .PREV DISCUSSION... /issued 205 PM CDT Fri Aug 27 2021/ SHORT TERM... Impressive cumulus cloud field across the area this afternoon although short-term solutions remain nearly void of showers or thunder. A couple solutions indicate shower chances developing near the New Mexico border in far northwestern Parmer County early this evening, while the HRRR lately has been indicating isolated coverage of showers or thunder across the extreme southern South Plains. Weak low level convergence does exist mainly on the Caprock, while southeast low-level wind components are leading to a few healthier cumulus or cumulus congestus over the north-central South Plains especially close to the Caprock escarpment. Forecast soundings indicate a likely subsidence bump around 9 to 10 thousand feet above the ground, weaker near the New Mexico border, but will make it difficult for updrafts to climb above this altitude. This is consistent with the indications for a weak upper level ridge overhead as well. For now, we are siding with the majority lack of support for showers and retaining a dry forecast for the evening. Overnight should remain mild with light southeast or southerly flow, and also modestly moist so areas of stratocumulus mostly near 5000 to 6000 feet above the ground could occur. Saturday, the weakness in the upper ridge is expected to remain overhead. And conditions otherwise look mostly unchanged other than a slight additional moisture increase. Again, solutions are lacking significant shower or thunderstorm signals for our area along with persistent though slightly weaker mid level subsidence bump. Perhaps could argue support for low thunder chances in the southwest Panhandle near the New Mexico border, but will keep forecast dry with temperatures off another degree or so owing to the gradual improvement in moisture. RMcQueen LONG TERM... The trend for showers and thunderstorms is gradually decreasing as the Polar Jet flattens and becomes zonal across the northern half of the CONUS during the day Sunday, out ahead of land falling Ida. A weak synoptic trough will still linger from a disturbance north of the Great Lakes region. Weak upslope flow across the South Plains combined with little to no capping inversion will favor isolated convection along the NM/TX state line in our northwest zones Sunday afternoon. Less forcing to the east looks to leave deeper boundary layer moisture untapped into the Rolling Plains. A stout ridge builds in between Ida to the east and the remnants of Nora to the west, when temperatures climb back into the low/mid 90s amid a dry air mass on Tuesday and Wednesday. H50 heights lower slightly for the end of next week as as the center of the ridge shifts east. Monsoonal moisture should fuel convection across the mountains of New Mexico, into next weekend, with any precipitation likely to remain well west of our CWA. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 09
Area Forecast Discussion
National Weather Service Melbourne FL
1029 PM EDT Fri Aug 27 2021 .DISCUSSION... Current-Overnight...Radar trends show scattered showers and isolated lightning storms over the local coastal waters. These will still develop and occasionally move onto the coast overnight, but many will diminish before making it too far inland. Most of the interior should remain mostly dry overnight, but cannot rule out a stray shower or two here. Primary threats from any heavy showers or storms will be occasional lightning, isolated wind gusts to around 40 mph, and torrential downpours leading to minor/nuisance flooding. Movement remains from the southeast toward the northwest at 20 to 25 mph. Overnight lows in the mid to upper 70s. Saturday...Previous Modified...After a dip in PW overnight, values return to 2.00" and above as the surface high over the coastal Carolinas begins to sink southward and Hurricane Ida continues its drift northwestward in the Gulf of Mexico. Locally, deep easterly flow will prevail once again and a similar setup with scattered to numerous onshore moving showers and isolated to scattered thunderstorms. Activity looks to be a little more favored across the interior, so will maintain PoPs up to 50-60% in the late afternoon hours. Highs will reach near 90F to the lower 90s across ECFL. && .AVIATION...Generally VFR conditions, though MVFR invof showers and isolated lightning storms thru Sat. Mainly dry over the interior overnight and occasional scattered onshore moving showers/storms, but they will likely diminish before they move too far inland. Latest HRRR showing drier conditions on Sat so will be interesting if this trend continues. Have "Vicinity" wording included in TAFs, but confidence not there yet for any tempo groups. Cell steering flow remains from the southeast toward the northwest. A tighter pressure gradient exists on Sat so will see our (E/ESE) surface winds a bit stronger with more gusts than this past day. && .MARINE...Overnight-Sat...Continuing Cautionary Statements for one more period (offshore), though it remains marginal. ESE winds 15-20 kts at times offshore with a diminishing trend thru the late night. Seas 4-6 ft offshore becoming 4-5 ft by daybreak Sat morning. Seas continue to subside to 3-4 ft near shore and 4-5 ft well offshore through the day on Sat. Scattered WNW moving showers/isolated lightning storms. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ Sedlock/Weitlich
Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
712 PM CDT Fri Aug 27 2021 .SHORT TERM...(This evening through Saturday night) Issued at 319 PM CDT Fri Aug 27 2021 Surface analysis this afternoon depicts a surface low over the triple point of the ND/SD/MN border with a warm front snaking SE into far southern MN and WI with a cold front back to the W. A more potent surface low lurks over far southern Saskatchewan province. Aloft, a weak ridge axis is aligned from Hudson Bay down the ridge of the Appalachians while a trough digs south from the western Canada into the northern Rockies. The surface warm front is expected to lift north through this afternoon as a shortwave trough axis rounds the southern periphery of the longwave trough into the Upper Midwest. Destabilization of the atmosphere is occurring with the diminishing of any cap across southern and eastern portions of the WFO MPX coverage area despite fairly expansive and low cloud cover. Some convection is ongoing in SE MN with CAMs (including the HRRR and NAMNest) suggesting additional convection developing closer to the TC Metro. It will be close as to whether the TC Metro sees thunderstorms through this evening while southern MN into western WI have better chances, due to more duration during peak heating of being warm-sectored south of the warm front. Have shown higher PoPs in southern and eastern portions this evening. There`s still the chance of isolated severe storms as SPC analysis shows MUCAPEs of 2000-3000 j/kg around the I-90 corridor but that gradient drops off quickly going north. In addition, while low level lapse rates are not impressive, mid-level rates are so it may be a challenge to get surface-based convection going. Closer to the warm front could see more rotation in individual cells before more organization takes place into clusters, leading to a damaging wind and large hail threat. However, as noted, most of this activity may well occur to the south and east of the metro and potentially south and east of the coverage areas as a whole. Any and all activity will diminish and push off to the east overnight through the first half of tomorrow, leading to a tranquil but warm overnight period. Lows tonight will only range from the lower 60s in central MN to the lower 70s near the IA border, including around 70 in the TC metro. Saturday continues to be a bigger concern with respect to severe weather and heavy rain. The longwave trough aloft will shift into the Northern Plains, placing the Upper Midwest into a strong mode of advection both in terms of moisture and PVA. Mid-level jetting of near 60kt is expected across the Dakotas which will effectively shift east across MN/WI mid-to-late day. Cap erosion by mid-afternoon with strong low-to-mid level moisture advection is expected, to the tune of lower 70s dewpoints for much of the coverage area. In advance of the cold/occluded front attendant from the aforementioned southwest Canadian low, rapid storm development is expected in western MN which will translate east into a well-organized line of strong to severe thunderstorms with plenty of moisture and lift to produce heavy rain along with a growing potential of large hail, damaging winds and isolated tornadoes. The tornado threat looks to be the initial threat upon discrete cell development, followed by large hail and damaging wind gusts as the storms organize into a linear mode. Best timing would be mid-afternoon into the evening. Rainfall amounts of 1-2" are again fairly common, which may again lead to localized flooding concerns. As SPC has already upgraded most of the area to an Enhanced Risk (along with WPC placing eastern and southern portions in a SLight Risk for Excessive Rain), residents and visitors are urged to remain weather-aware through Saturday night. The primary cold front will sweep across the region Saturday evening through early Sunday morning, pushing any and all precipitation off to the east and leading to clearing skies by daybreak Sunday morning. .LONG TERM...(Sunday through Friday) Issued at 319 PM CDT Fri Aug 27 2021 Sunday morning could still see some showers and thunderstorms in west central Wisconsin, but the bulk of the activity should occur Saturday into Saturday night. Behind this frontal passage on Saturday high pressure will move in on Sunday bringing an end to our days of wet weather. This break will be brief though as the pattern looks to remain active next week. Monday looks more like Sunday than it does any of the wet days this week with generally dry weather for most. Southwest Minnesota could see some precipitation though associated the advection of some warm moist air from the air mass associated with Hurricane Ida. Tuesday looks fairy quiet though as a ridge aloft builds into the Upper Midwest. Then Wednesday into the end of the week sets up similar to what we`ve seen late this week with a warm front setting up along the north of a ridge aloft. On the temperature front expect near normal temperatures with highs in the upper 70s through most of this period. Depending on how the rain chances set up though we could see some cooler weather later in the week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 712 PM CDT Fri Aug 27 2021 TSRA across southeastern MN will lift northeast and likely impact EAU for the next few hours. Otherwise, cigs and visibilities deteriorating later this evening at STC and AXN where dense fog is possible. Line of thunderstorms will fire over western MN during the early afternoon and push east through the mid evening, impacting all TAF locations. KMSP...No concerns tonight or Saturday morning. TSRA becomes increasingly likely late afternoon, with a decent chance of severe gusts (50+ kts) as it moves through between 00-02Z. /OUTLOOK FOR KMSP/ Sun...VFR. Wind W 10 kts. Sun night through Mon Night...VFR. Wind variable less than 5 kts. Tue...VFR. Wind SE 10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ SHORT TERM...JPC LONG TERM...NDC AVIATION...Borghoff
Area Forecast Discussion
National Weather Service Marquette MI
633 PM EDT Fri Aug 27 2021 .SHORT TERM...(This evening through Saturday) Issued at 402 PM EDT FRI AUG 27 2021 Low confidence remains heading in tonight`s forecast as model consistency/continuity continues to be poor. Water vapor imagery and RAP analysis indicates a shortwave lifting ne into the area today ahead of a broad western CONUS mid-upper level trough. PVA, isentropic ascent and increased moisture transport and theta-e convergence associated along and ahead of this shortwave has increased shower coverage late this morning/afternoon across especially central and eastern portions of the cwa. And with the showers and clouds hanging over the area, temperatures have stayed pretty steady this afternoon in the upper 50s to lower 60s north to the mid to upper 60s south. Big question tonight will be the evolution of convection as another shortwave is fcst to ride along the warm frontal boundary situated from southern MN into southern WI. This boundary is expected to move north into central MN and central WI as a shortwave trough approaches from the west. Based on current radar trends, it would appear that the HiRes-ARW and maybe the NSSL-WRFARW have the best handle with ongoing convection at the moment. Also like the HiRES- ARW evolution of convection initiating along the frontal boundary over southern MN early this evening and then tracking it ene into central WI and then south central Upper Mi later this evening. This ene track of more organized convection would makes sense since the better instability is fcst by models to stay generally south of the U.P. or along and just north of the frontal boundary. Will generally follow this solution for fcst details into tonight as I expect there should be a bit of a break in steady showers toward early evening, but then showers should ramp up again, especially over south central and eastern sections of the cwa later this evening into the early overnight, as the second wave of convection works its way across the area. Menominee County is in a marginal risk later tonight for stronger to marginally svr storms, but with elevated instability and effective shear looking marginal would expect stronger to severe storms to stay mostly south of the area. Model trends are for storms to dissipate and move east of the area late tonight. Min temps should be mostly in the lower to mid 60s tonight. Expect a mostly quieter weather across the area on Saturday as shortwave ridging builds in from the west, although it will be quite muggy with dew points ranging generally from the mid 60s north to perhaps the lower 70s south and max temps expected in the upper 70s to lower 80s. Max temps will be tricky as I`m not sure how much sunshine we will see before clouds fill back in ahead of the approaching cold front from the west late in the day. Building instability ahead of the front will bring a chance of showers and storms back into the western cwa late Sat afternoon. .LONG TERM...(Saturday night through Friday) Issued at 338 PM EDT FRI AUG 27 2021 Active with some potential severe weather is possible Saturday night across the region before we progress into a dry pattern that will last through a good portion of next week. An eastward propagating line of showers and thunderstorms is expected to develop upstream ahead of a cold front that`s tied to an upper level trough moving through the Northern Plains. There is good model agreement that the line could be over the far western portions of the forecast area with a southward extension into Wisconsin by 0Z Sunday. Models suggest plenty of instability developing during the day Saturday ahead of the convection, and with some support provided by a decent 850mb LLJ, thunderstorms with a damaging wind and hail potential should move into the west and central before midnight. With PWATs expected to be well over the 90th percentile moving average, expect any thunderstorm to be capable of producing heavy downpours. As instability wanes, expecting cold pool dominated strata-precip to fill in behind the initial line and spread east to northeastward for the remainder of the night. As the front moves into the west by Sunday morning, another round of precip may accompany it, but would be waning if so. Expect the front to shift eastward through Upper Michigan on Sunday, with some redeveloping shower and thunderstorm activity being possible out ahead of it Sunday afternoon in the east half. As surface cyclogenesis tied to the upper level trough takes place over Ontario, increasing pressure gradient and CAA behind the front will support some breezy winds near 30 mph across the Keweenaw by Sunday afternoon. By Sunday night, ridging extending across the Plains northward into north-central Canada will shift eastward and set off a prolonged calm and dry spell across the region. Guidance suggests we could be dry through at least Thursday. High temperatures after the cold front will settle into the 70s for much of the coming week. Overnight lows will be near 60F by the lakeshores and 50s or mid 40s in the interior are also expected. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 633 PM EDT FRI AUG 27 2021 A somewhat moist east-southeast flow will persist over the area through the fcst period. This will result in IFR/LIFR conditions persisting at KCMX and KSAW in a moist upslope flow through much of the period with maybe some improvement during the early afternoon on Saturday. MVFR conditions at KIWD will also lower to IFR/LIFR late tonight before improving to VFR later in the period. There is plenty of fcst uncertainty with timing and coverage of showers, but expect at least isolated to scattered coverage over the terminals into tonight as a warm front slowly approaches from the south. Best chance of showers looks to be at KSAW. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 402 PM EDT FRI AUG 27 2021 A tight pressure gradient between high pressure over Ontario and low pressure in the Plains will continue to result in gusty easterly winds perhaps as high as 30 knots into this evening. A warm front will then lift northward towards the lake tonight, bringing winds around to the southeast. As the high pressure north of the lake lifts east on Saturday, the gradient will relax and the winds will follow, falling blo 20 knots by Saturday morning. As a front crosses Lake Superior on Sunday westerly winds could gust as high as 30 knots. High pressure building over the area early next week will lead to calmer conditions through the middle of next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement until 9 PM EDT this evening for MIZ005- 014. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...JP AVIATION...07 MARINE...Voss
Area Forecast Discussion
National Weather Service Pocatello ID
125 PM MDT Fri Aug 27 2021 .SHORT TERM...Tonight through Sunday night. One shortwave will depart the region this afternoon while a second one drops in from the northwest tonight. Models offer only some showers around the Island Park area tonight. Some lingering wind gusts are expected until around sunset tonight, so will keep the Lake Wind Advisory active through then. There is notable improvement in the smoke forecast as observational trends show improving visibility and better air quality. Some As the second shortwave departs to the east, the region will come under the influence of weak ridging. This will lead to dry weather that should last through Sunday night. Hinsberger .LONG TERM...Monday through next Friday. A broad upper trough over WRN Canada will shift east through the NW states Monday and Tuesday resulting in a dry SW flow aloft across the region and increasing surface winds into Tuesday afternoon. The trough lingers over Alberta Wednesday while a surge of sub-tropical moisture makes its way north through Utah into the SE mountains. As we have discussed over the last couple of days, the operational GFS and ECMWF (as well as the ensembles) begin to show quite a bit of variability in the model solution space Thursday and Friday. Hence, we will remain in lockstep with the National Blend Solution until we see more consolidation toward a reasonable solution. Huston && .AVIATION...A dry upper trough was working east through the region early this afternoon resulting in breezy west winds across the region. Winds are expected to decouple and diminish after sunset with VFR conditions prevailing through Saturday. Huston && .FIRE WEATHER...Breezy and dry conditions will persist until around sunset tonight, particularly across the Arco Desert. The shortwave that is triggering the winds is also bringing some showers to the Island Park area and extreme northern Lemhi county. Showers may persist through the night until the shortwave pushes to the east around sunrise tomorrow morning. Humidity will trend lower starting tomorrow, though winds over the weekend should remain fairly light. With the approach of another upper trough on Monday, we`ll see winds increase across the region. This could lead to critical fire weather conditions, mainly across the Snake Plain. Will continue to evaluate the need for Red Flag Warnings Monday as models update. Afternoon thunderstorms are back in the forecast starting Tuesday over zones 410, 411, and 413. Hinsberger && .AIR STAGNATION...Significant improvement in smoke is expected today as shortwave feature drives through and changes flow aloft to a more westerly direction. HRRR smoke, both near-surface and vertically integrated, show drastic clearing through today and continuing through most of the weekend. Flow does turn back to the southwest late Sunday, so we could see smoke return to East Idaho by early next week. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... Lake Wind Advisory from noon today to 8 PM MDT this evening for IDZ054. && $$
Area Forecast Discussion
National Weather Service Sacramento CA
229 PM PDT Fri Aug 27 2021 .SYNOPSIS... Hot and very dry through the weekend. Locally breezy north winds will lead to areas of critical fire weather conditions over the northern Sacramento Valley into Saturday morning, with a Red Flag Warning in effect. Cooler weather returns next week. Breezy southwest winds early next week over Sierra ridges. && .DISCUSSION... Satellite shows smoky skies across much of the area. Northerly flow has brought wildfire smoke down through the Valley. Easterly flow in the morning brought dense smoke into the Motherlode and eastern Sacramento suburbs. The diurnal flow has reversed, with westerly winds shifting some of the denser smoke in those areas further to the east. The HRRR smoke model shows this pattern reversing overnight, with dense smoke bake into the Motherlode and eastern Sacramento suburbs by early Saturday. Smoke continues to be an issue across the area through the weekend. For air quality forecasts check with your local air quality district or Northerly winds and low humidity have brought Red Flag conditions to the northern and central Sacramento Valley and surrounding areas today. Redding currently has a humidity down to 9% with winds gusting to 25 mph. Gusts of 25-30 mph are likely over the northern half of the valley, and locally further south along the western edge. Winds should gradually decrease overnight, but overnight recoveries should be poor to moderate (25-40%) and winds should pick up again early Saturday. The Red Flag Warning continues until 11 am Saturday. High pressure rebounds a bit over the weekend in the wake of the short-wave. 850 mb temps climb to the upper 20s to around 30C over the weekend. Given the amount of wildfire smoke, surface temperatures will probably not realize their full potential. Nevertheless, it will be hot with most Valley high temperatures forecast to range from 100 to 105 (about 10 degrees above average). Widespread moderate heat risk is expected. The next upstream trough moves in early next week bringing cooler temperatures and a return of onshore flow. && .EXTENDED DISCUSSION (Tuesday THROUGH Friday)... Upper troughing remains along the West Coast through the extended forecast period. This will result in below normal high temperatures Tuesday into Friday. Locally breezy wind possible at times through the Delta and over higher terrain, mainly afternoons into evenings. This will likely clear some of the smoke out of the Valley. Southwest ridge winds over the mountains could bring fire weather concerns. && .AVIATION... VFR with MVFR to locally IFR at times next 24 hrs due to area wildfire smoke. Generally elevated smoke layers 040 and 100 AGL. Gusty northerly flow through the Sacramento Valley today. Gusts 20 to 30 kts possible through around 03 UTC. && .STO WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 11 AM PDT Saturday for Central Sacramento Valley in Glenn, Colusa, Yuba, Northern Sutter, and Butte County Below 1000 Ft-Eastern Mendocino NF-Eastern Portion of Shasta/Trinity NF-Northern Sacramento Valley to Southern Tehama County Line Below 1000 Ft-Northern Sierra Foothills from 1000 to 3000 Ft. Includes portions of Shasta-Trinity and Butte Units- Southeast Edge Shasta-Trinity NF and Western Portions of Tehama- Glenn Unit. && $$
...Update to aviation forecast discussion...

.DISCUSSION... Issued at CDT Fri Aug 27 2021 Late this afternoon, an upper trough was located across the central Rockies. A downstream upper level ridge axis extended from the southeast US north-northwest into the southern Great Lakes. At the surface a weak sfc trough axis extended from south central NE southwest into southeast CO. There may be enough convergence along this sfc trough axis to provide ascent for a few isolated thunderstorms. The effective shear will be weak but MLCAPES will be 100-1500 J/KG, so any pulse storm may produce gusty winds. I placed a 20 POP across the northwest counties, in case isolated storms managed to develop. The FV3 CAM does forecast a weak line of storms developing across Republic CO after 20Z. The HRRR develops isolated storms across northwest and west central KS. The main synoptic front has lifted northward across central ND. Tonight, any storm that manages to develop in the northwest counties will dissipate after sunset. Saturday through Sunday night, The upper level trough across the central Rockies will lift east-northeast across the northern and central Plains. Stronger low-level CAA across the northern Plains will cause the surface front to shift southward across SD and into north central NE during the afternoon hours. Several CAMs show a line of storms developing along the front, then shifting southeast across southern NE during the evening hours and into north central KS after Midnight. If these storms can keep their intensity, there might be a few damaging wind gusts within the line of te storms. However, the effective shear will weaken below 20 KTS once this line moves into north central KS and the outflow may outrun the line of storms causing the line to weaken. At this time SPC has a marginal risk out for portions of north central KS in case the line can hold together as it moves southeast across north central KS after Midnight into early Sunday morning . It looks as if the line of storms will continue to weaken and most CAMs show the line of storms falling apart across the central counties of the CWA during the morning hours of Sunday. Highs on Saturday will range from the lower to mid 90s with heat indices around 100 degrees. Thunderstorm chances on Sunday will dependent on where the outflow boundary/front ends up during the afternoon hours. The 3KM NAM shows the front shifting south of the CWA during the afternoon hours. If this were to occur the better chance for thunderstorms will develop across south central and southeast KS. If the front is slower and stalls out across the CWA as forecasted by the ECMWF and GFS, then thunderstorm chances will increase across the CWA. HOwever, the effective shear will be weak, around 10 KTS, so I`m not expecting any of the storms to be severe. The H5 trough will lift northeast across the Great Lakes States. Hurricane Ida will make landfall across the central LA coast late Sunday night. Highs on Sunday will be a bit cooler with mid 80s along the NE border to lower 90s south of I-70 Monday through Thursday, An upper level trough will move into the northwestern US as the Hurricane becomes an extra tropical upper low. An upper level ridge will amplify northward across the southern and central Plains Tuesday into Thursday. Expect a slight warm up with highs back into the lower to mid 90s. The H5 trough across the northwestern US will move east across the northern and central Plains, as it passes north of the CWA, a weak surface && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 618 PM CDT Fri Aug 27 2021 VFR conditions are expected through the TAF period. Similar to last night, the strongest portion of the LLJ will remain west of the terminals, mitigating any LLWS concerns. Otherwise, southerly winds will remain near 10 kt through the overnight hours with gusts near 20 kt returning by mid-morning. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Gargan AVIATION...Baerg
Area Forecast Discussion
National Weather Service Las Vegas NV
202 PM PDT Fri Aug 27 2021 .SYNOPSIS...Excessive Heat Warnings are in effect through Sunday for parts of the area with dry conditions continuing and very hot temperatures expected. Monsoon moisture will creep into our area from the southeast, which could eventually limit afternoon heating in our southern areas. The increasing moisture could lead to a few isolated showers and thunderstorms developing in Mohave County on Sunday. Shower and thunderstorm coverage could expand further into our area next week as remnant tropical moisture from Nora is injected into the Desert Southwest. && .DISCUSSION...Through next Friday Little has changed in the overall impacts we expect in the coming days. Temperatures will be 5 to 7 degrees above normal this weekend with a smattering of zones covered by excessive heat warnings. There is a new active wildfire in central Nye County. Smoke plume is visible on satellite this afternoon contributing to the regional smoke/haze. HRRR Smoke output continues to keep widespread smoke/haze across Inyo and Esmeralda Counties. But can not rule out hazy conditions anywhere across the southern Great Basin and Mojave Desert this weekend. Guidance still showing a minor influx of monsoon moisture moving back westward into Mohave County maybe as early as Saturday afternoon. Its better looking for Mohave County, southeast California and Clark County by Sunday and Monday. For Tuesday-Thursday: Attention then turns to how moisture from the remnants of Nora comes into play. Official NHC forecast track keeps Nora at hurricane strength into the southern Gulf of California before making landfall as a tropical storm along the southern Sonora coast between Guaymas and Bahia Kino. The current forecast track fits very similar to Hurricane Lorena in 2019. There is uncertainty in the track and strength of the storm as any interaction with the southern tip of Baja would weaken the system quicker. Confidence that moisture from Nora reaches into the Desert Southwest is high and models have been consistent showing PW values peaking Tuesday- Thursday. However, just how far west this moisture reaches and impacts our area remains a bit more uncertain. Latest guidance suggests a sharp moisture gradient will develop across western Arizona and eastern California and southern Nevada. 12Z ECMWF ensemble QPF continues to indicate Mohave County will likely see some of our higher precip. amounts with values decreasing steadily moving west into eastern California and southern Nevada. Stay tuned as any shift west in this moisture would change the outlook for eastern California and southern Nevada. && .AVIATION...For McCarran...Southwest winds are expected to develop this afternoon and become gusty at times between 22z-02z this evening. Wind speeds between 10-18 kts with occasional gusts to 20 kts are likely. These winds will gradually diminish by 03z with southwest winds around 10 kts remaining overnight. Winds will again become light and variable after 14z and then gradually become northeast to east around 7 kts between 15z-20z. Southwest winds will once again develop Saturday afternoon with gusts up to 18 kts. Mostly clear skies expected through the period. For the rest of southern Nevada, northwest Arizona and southeast California...South or southwesterly winds each afternoon and early evening with gusts of 15-20 knots possible through Saturday. Winds will become mainly light and variable overnight with speeds generally less than 7 kts in most areas. Lingering haze is likely in the Sierra and Owens Valley which may affect visibility into Saturday around KBIH, but not expecting the visibility to drop below 6 miles at this time. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ DISCUSSION...Pierce AVIATION...Gorelow For more forecast information...see us on our webpage: or follow us on Facebook and Twitter