Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/19/21

Area Forecast Discussion
National Weather Service Amarillo TX
1040 PM CDT Sun Jul 18 2021 .AVIATION...06Z TAF... VFR conditions expected through 18Z with the exception of KGUY which could see some IFR to LIFR conditions for an hour or two, mainly around sunrise. Some low clouds, fog, or mist may develop during the peak cooling time around 12Z. Thunderstorms are not quite done in the area mainly for KAMA. However, prevailing impacts are not expected and have left thunder out of the TAF for now. Once 18Z comes around thunderstorms will once again be a possible threat to VFR conditions. For now have PROB30 groups for KDHT and KAMA. Hoffeditz && .PREV DISCUSSION... /Issued 607 PM CDT Sun Jul 18 2021/ AVIATION...00Z TAFs... Summer thunderstorms will continue to threaten the combined Panhandles this evening and in to the overnight hours. Categorical degradation will be possible if a terminal is directly impacted by a storm. KDHT will be next in line to be impacted by at least VCTS in the first 2 hours or so of the 00Z TAF period. KAMA will have a better chance for TS impacts after 03Z. Have kept TAFs as optimistic as possible right now, but amendments may be needed at times. Wind gusts up to 40 kts and torrential downpours will be possible with thunderstorms. VFR conditions with light southerly winds will be prevalent outside of thunderstorms. Hoffeditz PREV DISCUSSION... /Issued 244 PM CDT Sun Jul 18 2021/ SHORT TERM (Today through tomorrow night)... Overview: Somewhat tricky forecast today as we start shifting away from the northwest flow aloft, yet continue to have the tropical airmass in place across the Panhandles. It doesn`t take much with this type of airmass to get convection going, but we have signals that could inhibit thunderstorms today. With that said, any thunderstorms that happen to develop could become strong to severe, especially central and eastern parts of the combined Panhandles. Main threats for any thunderstorms will be localized flooding, lightning, and damaging wind gusts. Further Details: H5 center of high pressure residing over the Four Corners region will slowly push northward today. By 00Z (7pm), the center could be over eastern parts of the Great Basin. During this transition, we are going to go from the northwest flow we have been experiencing for several days to a more northerly flow. We still have the tropical airmass in place across the area, but the northerly flow pattern isn`t the best for convection. That said, we have a convective complex pushing in from Nebraska and western parts of Kansas. As of 2pm, a noticeable outflow boundary is heading our way ahead of the complex, and could reach the Oklahoma Panhandle by 3-4pm as storms are already starting to fire up. If this trend continues, we could have thunderstorm activity through about midnight. We need this boundary as we are lacking energy aloft. In fact, forecast soundings from the HRRR and RAP indicate subsidence aloft as seen from an elevated mix layer (EML) around 500mb-400mb. This EML will inhibit storms, but with the boundary pushing in and some subtle semblance of energy aloft, this could help initiate storms this afternoon and evening. If the convective complex doesn`t make it this far south, we may end up dry across most of the area besides maybe a few pop-up thunderstorms from convective temperatures. Also, hodographs are small and there isn`t much shear, so widespread severe weather is unlikely today/tonight even with the outflow boundary from the complex. Localized flooding, lightning, and isolated damaging wind gusts will be the main threats. Weak lapse rates are not allowing for much instability, but there could be enough MLCAPE to trigger a couple rogue storms producing hail around an inch in diameter. For tomorrow, its another one of the situations where today`s convection--or lack thereof--will impact our thunderstorm potential for tomorrow. Currently thinking if the outflow boundary doesn`t make it into our area today/tonight, it may make an entrance tomorrow morning and afternoon, increasing our threat for thunderstorms during this time. For now, we will have to wait and see what happens today, but any storms that form tomorrow could become strong to perhaps severe with similar threats as today. Only change with tomorrow is the lapse rates are steeper, so we could have a greater threat for large hail tomorrow. Guerrero LONG TERM...Tuesday through Saturday... Cooler temperatures are expected through the beginning of the long term period before temperatures rise back to near normal for this time of year. After Tuesday morning, drier conditions will hold through Saturday. A H500 ridge will extend across the central CONUS on Tuesday, with the center of high pressure located near the four corners region. The NBM is suggesting a stray shower or storm may remain in the far southwestern Texas Panhandle after 12z on Tuesday. However, latest guidance has most of this activity south of the CWA, so have reduced POPs across the southwest after 12z. Otherwise, the cooler than normal pattern continues through Wednesday, as the main axis of the upper level ridge remains off to the west. Looking towards Thursday and beyond, the ridge will begin to slowly drift towards the east. A weak low pressure system with associated trough attempts to undercut the ridge across central and west Texas. With the upper level high pressure centered over the central Rockies near Colorado and a possible weak upper level center of low pressure to our south, northeasterly to easterly flow aloft is expected. This type of flow is not favorable for precipitation, so drier and warmer conditions are expected through the rest of the extended. Muscha/Ward && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$ 36/89
Area Forecast Discussion
National Weather Service Bismarck ND
959 PM CDT Sun Jul 18 2021 .UPDATE... Issued at 956 PM CDT Sun Jul 18 2021 Quiet weather continues over most locations, but the chance for a few isolated storms continues, mainly over western locations. Right now one is located just to the west of the border near Wibaux, but previously a few were located to the east. Still do not expect severe weather with these storms. UPDATE Issued at 630 PM CDT Sun Jul 18 2021 Isolated thunderstorms have developed over western portions of the area, but these have remained tame. Expect this trend to continue as the evening goes on. Going forecast remains in good shape, with minimal changes needed. && .SHORT TERM...(This evening through Monday) Issued at 1239 PM CDT Sun Jul 18 2021 Hot and hazy conditions highlight the short term forecast period. Currently, surface low pressure was situated over eastern Montana, with a weak defined surface trough into southwest Manitoba. Aloft, the latest water vapor imagery shows a weak impulse over eastern Montana heading toward the North Dakota border, but you can also see the building ridge of high pressure over the Northern Rockies and into the Northern Plains. SPC mesoanalysis page shows 1500-2500 g/kg MLCape over most of western and central North Dakota, but also with a good amount of Inhibition. Latest NUCaps sounding from near Minot shows around 800 g/kg MLCape with a CIN around 115, or roughly twice that of the RAP analysis. The strongest low level moisture convergence remains north of the border and the weak impulse over eastern Montana will be working through a building ridge. We have therefore trimmed back our pops for late this afternoon and this evening. A few of the normally over zealous CAMS still do indicate some convection developing over or moving into western ND late this afternoon/early this evening, but even this is relatively tempered. The latest few runs of the RAP/HRRR have been completely dry. We will keep a mention of an isolated storm in the far west late this afternoon, then mainly far west and north central this evening. Earlier depiction of Canadian convection dropping south into our eastern CWA late tonight has also backed off and shifted more north and east, just clipping northeast ND. Can`t completely discount something around the Turtle Mountains, but our given guidance has this area dry now, and with the current trends, will leave it dry. It will be another warm night, with lows mainly in the mid and upper 60s. As was mentioned in the previous discussion, Monday is now looking to be the hottest day of the week as the upper ridge surges into eastern Montana and far western North Dakota. With 850 MB temperatures around 30C into western ND and mid and upper 20s as far east as the Highway 83 corridor. Temperatures of 100-105 are possible across western ND with temperatures around 100 possible across central ND. There is a frontal boundary over southern Canada that tries to sneak south into north central and northeast ND, keeping temperature in the upper 80s around the Turtle Mountains. This boundary will be a focus for isolated afternoon and evening thunderstorms Monday, with areas south of here remaining too stable for thunderstorms. Two concerns on Monday are fire weather issues west and the potential for a head advisory west and central. The overnight shift mentioned near critical fire weather conditions west on Monday and Tuesday. Afternoon dewpoints drop down to around 15 percent in the far west central and southwest, but the winds look to be rather light, even a bit lighter than what was though on previous shifts. We do mix out nicely in the west but winds are strongest near the surface and weaken and shift from south to north as you go up and you`ll need to get above around 600 MB to get some stronger winds above 20 knots to work down to the surface. Will keep the mention of near critical and let the evening and overnight shifts take another look. If we could get some stronger winds to mix down for a sufficient amount of time, a Red Flag warning would probably be needed given the hot temperatures, low humidities and drying vegetation. As for possible heat headlines, will also let the evening and mid shift take a look. Max apparent temperatures do reach as high as 103 in a few spots for a brief period Monday afternoon, roughly along the Missouri River Valley. Afternoon dewpoints are around 5-10 degrees lower than today, and maybe even more southwest, so there remains enough uncertainty with the actual values and the areal extent and duration, to let the later shifts take another look. Either way, it will be hot Monday and we continue to advertise this via social media. .LONG TERM...(Monday night through Sunday) Issued at 1239 PM CDT Sun Jul 18 2021 Hot temperatures and periodic thunderstorm chances highlight the long term forecast period. After Monday, deep upper level low pressure spinning off the Pacific Northwest coast through mid-week, will eject multiple embedded waves eastward, then lifts east-northeast across southeastern and central Canada Thursday through Saturday. The embedded waves will effectively weaken the ridge over time, and will also bring periodic chances for thunderstorms to the Northern Plains during the work week. Lots of uncertainty with these smaller scale features more than 24 hours out regarding precipitation chances. While temperatures will cool a bit as mid level heights slightly fall, still very warm through Friday with highs in the 90s along with a few locations seeing 100 as well. We do see stronger winds on Tuesday, but temperatures and humidities may also not be as high. Will keep the Near Critical mention for fire weather conditions in the west again Tuesday. Also not sure about the impact from an increase in smoke aloft from the wildfires to our west and north will have on daytime highs next week. Local research indicates higher levels of smoke aloft can significantly reduce daytime temperatures. Looking at the latest HRRR and Canadian smoke models, we don`t necessarily see a continuous stream of high amounts of smoke aloft, but our synoptic setup is one which we don`t see the continuous high amounts of smoke, but occasional shots, and the smoke keeps re- circulating around and around the northern plains. Not sure if this will have a huge affect on daytime high temperatures, but it certainly won`t help make it warmer. Height falls across the Northern Plains will be much more noticeable late in the week/next weekend, with NBM daytime high temperatures more in the mid 80s to lower 90s next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 630 PM CDT Sun Jul 18 2021 Isolated thunderstorms this evening western North Dakota, possibly spreading northeast as the evening goes on. Have mentioned a VCTS in the KDIK TAF as a few storms have developed near that area. Did not mention in other TAFs as confidence remains quite low. Otherwise, VFR conditions will prevail. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JJS SHORT TERM...TWH LONG TERM...TWH AVIATION...JJS
Area Forecast Discussion
National Weather Service Dodge City KS
647 PM CDT Sun Jul 18 2021 ...updated aviation section... .SHORT TERM...(This evening through Monday) Issued at 235 PM CDT Sun Jul 18 2021 A chance of thunderstorms will continue this afternoon as an MCS moves through the area. Precipitation chances will then be confined to central Kansas overnight with partly cloudy skies elsewhere. Any thunderstorms that do develop across central Kansas should move out of the area by tomorrow afternoon with decreasing cloudiness. Winds will generally be light and form the southeast through tomorrow with the exception of when thunderstorms move through. As for temperatures, lows tonight look to dip into the mid 60s with highs tomorrow in the mid to upper 80s. .LONG TERM...(Monday night through Sunday) Issued at 235 PM CDT Sun Jul 18 2021 Dry conditions are expected through the majority of the long term forecast as an upper level high slides east and over the Plains with high pressure being the dominate feature at the surface. A few models suggest a slight chance of precipitation as we head into the weekend but this is many days out and will need to be monitored through future model runs. As for temperatures, highs will start out in the upper 80s Tuesday with 90s expected through the remainder of the long term forecast. Lows will generally be in the 60s with a few low 70s entering central Kansas mid to late week. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 646 PM CDT Sun Jul 18 2021 A severe MCS has exited the area into western Oklahoma, while leftover stratiform precipitation from decaying convection continues over the far southwest counties. Based on most recent convective allowing models and latest mesoscale trends, we`ll discount the NSSL WRF`s overnight and monday convection as the HRRR took the MCS much farther east than did the aforementioned model. Therefore a light easterly surface wind and overall clear/VFR category forecast for the local terminals. Given the additional earlier rains and upslope flow Tonight, there might be some favored area of ground fog development, but not enough confidence exists to support adding to any terminals at this time. && .PRELIMINARY POINT TEMPS/POPS... DDC 66 86 63 87 / 0 10 10 0 GCK 64 85 62 86 / 0 10 10 0 EHA 64 88 63 86 / 80 20 10 0 LBL 65 86 63 85 / 10 20 10 0 HYS 66 86 61 88 / 0 10 10 0 P28 68 88 63 89 / 0 20 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Hovorka_42 LONG TERM...Hovorka_42 AVIATION...Russell
National Weather Service Hastings NE
956 PM CDT Sun Jul 18 2021 ...Short Term Update... .UPDATE... Issued at 956 PM CDT Sun Jul 18 2021 - Follow-up to earlier comments about overnight fog potential: Although still do not think truly widespread dense/impactful fog is likely for the Monday AM commute, have changed course a bit from last discussion a few hours ago and opted to blanket the entire CWA with generic "patchy fog" wording for the majority of the 4-10 AM time frame on latest update. For one thing, last few HRRR visibility runs are now starting to hint more at at least limited fog potential especially in our far eastern zones. Secondly, have some concern that models may be under-doing the contribution to boundary layer moisture/RH from the decent coverage of generally 0.25-1.50" (localized higher) rain that fell across much of our southwest 1/2 this morning. Last but not least, we admittedly got caught off guard a little bit this morning with at least brief dense fog in parts of the area (including the Tri Cities) and would rather at least get basic fog potential into the forecast this time around (especially for a weekday morning/commute). While patchy/limited dense cannot be ruled out, will defer to incoming night shift to better pinpoint any areas where the "fog throttle" might need to be hit a little harder, but for now at least the basic fog potential is in there. UPDATE Issued at 809 PM CDT Sun Jul 18 2021 Some comments solely focused on the next 12-16 hours (through mid-late morning Monday), largely echoing the same sentiments as preceding day shifter discussion... - Rain/thunderstorm chances: The main forecast change/update so far this evening was to delay the onset of low-end thunderstorm chances/PoPs until the post- midnight hours, but still keeping them focused mainly within the southwestern 1/3 or so of the CWA (mainly SW of a Kearney-Osborne line). Honestly, did consider removing all mentionable chances completely based on the consensus of most of the latest model data (including past several HRRR runs) and just going with "silent Pops" (less than 15 percent) in official products. However, considering that earlier model runs today (including 12Z HRRR/HRW NSSL/HRW ARW and even the ECMWF) suggested that at least spotty activity could flare up mainly sometime between 2am-sunrise, not to mention the fact that convective coverage has "overachieved" the past couple of mornings in terms of likelihood/coverage, felt it would be prudent to hang onto some smallish 20-30 PoPs for now. For sure though, support for early Monday morning convection does NOT look as favorable as it did for Sunday morning, as for one thing, the presence of any subtle mid level disturbance and resultant narrow corridor of low-mid level moistening/convergence diving down from the north looks even more nebulous and/or non- existent this time around. That being said, IF any convection does form (again a huge "if"), it could persist for at least a few hours past sunrise as it gradually departs to the south- southwest, so hung onto 20 Pops through mid-late morning for our extreme southwest CWA. Last but not least, even IF convection does manage to form early Monday morning in our west-southwest zones, odds strongly favor it being non-severe given fairly weak instability (generally no more than several hundred J/KG of elevated CAPE) and only modest deep-layer shear around 25-30KT). && .DISCUSSION...(This evening through Sunday) Issued at 301 PM CDT Sun Jul 18 2021 Convection this morning has pushed south of the local area, and as skies cleared this afternoon, a bit of cumulus has filled in across the local area. Expect this cloud cover to thin by early evening...with another potential round of thunderstorms possible late tonight through early Monday morning. Overall...the confidence for storms tonight has decreased a bit with the latest runs of the HRRR/RAP/NAM all coming in mostly dry overnight...but previous runs hinting at some isolated convection mainly west of Highway 281 late tonight through early Monday morning where there is forecast to be an area of weak convergence and potentially another weak upper wave to help spark convection. Despite the trends of latest models towards less activity...wanted to keep in some isolated convection based on what has occurred the past few nights along with the subtle hints for something forming after midnight. That said...anything that does form is not expected to be severe and continued with non-severe thunderstorm wording in the HWO. The other concern overnight was the potential for fog...which we saw across much of the local area this morning. With elevated dew points and light winds with a southeasterly component...this is not completely out of the question...although downplayed the potential due to low probs in the SREF guidance and no indication across our local area in the HRRR...although this potential may need to be revisited later this evening. As we then transition into the work week, warmer and drier weather appears to be in store for the local area as the upper level ridge to our west begins to tilt and transition eastward. This should shift storm chances away from the local area and result in a gradual warming trend as heights aloft build across the local area. While there could be a few weak disturbances brush the fringes of the local area late in the period...confidence of timing and location is low...and opted to remove the small pops that were given by the blend of models this afternoon...keeping conditions dry through the end of the work week and into next weekend. As we dry out...also expect temperatures to rise...with highs climbing well above normal towards the end of the work week...with some models hinting at highs near 100 with the potential for heat index values climbing above 100. In fact...looking at some of the long range guidance...this could be the beginning of a prolonged warm stretch across the local area, which we will continue to monitor as it unfolds. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday) Issued at 809 PM CDT Sun Jul 18 2021 Ceiling/visibility/precipitation: Have maintained a VFR ceiling/visibility forecast, and with at least medium-high confidence that this should verify through the vast majority of the period. However, cannot rule out at least a brief period of sub-VFR conditions regarding both elements: 1) For ceiling: time-height relative humidity progs clearly show that a low-end VFR ceiling is quite possible at times later tonight into part of Monday daytime, and it wouldn`t take much for any ceiling to at least briefly dip into MVFR territory...2) For visibility: Although not currently expecting a repeat of the dense fog issues that briefly impacted both KGRI/KEAR this morning, at least a little haze/light fog seems plausible a few hours either side of sunrise. As a result, have introduced a low-end VFR "6SM BR" to the TAFS 09-15Z to hint that VFR visibility may not be a slam dunk. Precipitation-wise, although there is still a very small chance of showers/weak storms perhaps affecting especially KEAR within a few hours either side of sunrise, this chance is now considered so low that even a basic "vicinity"/VCTS can no longer be justified and has been removed. Winds: Another low-impact period here, as sustained speeds should average under 10KT throughout, with direction prevailing somewhere between easterly and southerly (in other words, generally southeasterly). && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...Pfannkuch DISCUSSION...Rossi AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Lake Charles LA
945 PM CDT Sun Jul 18 2021 .UPDATE... Evening update. && .DISCUSSION... Showers and thunderstorms have dissipated over the area. Skies will be partly cloudy to mostly clear overnight. A few nocturnal showers and thunderstorms could develop along the coast into the early morning hours. However, chances will be low. Chances will increase after the sun rises. The 00Z HRRR is indicating a possible convective system making its way into our area from the north late Monday into Tuesday. There does appear to be model consensus regarding this, as the GFS and NAM are indicating significant development in this timeframe as well. Thunderstorms will be expected Monday into Tuesday as an upper-level trough continues to dig south into our area. This aligns with the current forecast, therefore no changes were made. 55 && .PREV DISCUSSION... /issued 647 PM CDT Sun Jul 18 2021/ DISCUSSION... 19/00Z TAF Issuance. AVIATION... Widely sctd aftn SHRA/TSRA are ongoing at this time, and AEX/LFT/ARA could see brief impacts from SH or TS over the next hour or two before convection finally dissipates with loss of daytime heat. Conditions are currently VFR with a mix of SCT CU/CB/CI per recent vis satellite. VFR expected to prevail overnight with lower clouds diminishing. Another day of active weather is expected on Monday, with a little better coverage once storms develop by mid to late morning. Not only is convection expected along an inland-moving seabreeze boundary acrs southern areas but also acrs cntl LA where outflow driven convection (associated with a front north of the area) is expected to be sliding southward. Locally reduced cigs/vsbys and gusty winds can be expected with SHRA/TSRA, but otherwise expect VFR conditions amid SCT-BKN cloud cover. Winds will be light and vrbl, bcmg southwesterly during the day Monday. 24 PREV DISCUSSION... /issued 252 PM CDT Sun Jul 18 2021/ SHORT TERM [Today through Tuesday Night]...The overall pattern across the Conus has not changed much over the past week with a large upper ridge out west and an upper trough located over the east half. The only change lately is the pattern has been getting slightly more amplified today and this will continue into early this week. As the ridge builds in the west and the trough digs south across the east, a cold front will advance into the deep south. Ahead of the boundary moisture will pool which will increase rain chances Monday. This front is expected to stall across the East Texas Lakes Region and CenLA by Tuesday/early Wednesday while the base of the upper trough cuts off. Widespread rain and storms can be expected Monday evening through Tuesday as the front moves in and the forming upper low moves over the region. 05 LONG TERM [Wednesday through Sunday]... By Wednesday, an extension of the E CONUS trough aloft is stretched towards the Southern Plains, cutting off over the Gulf states and retrograding westward. At the surface, a weak frontal boundary is progged to stall just north of the forecast area and begin to wash out. Airmass south of the boundary will remain quite moist with PWATS around 2.00", so combined with the aforementioned forecast elements, PoPs remain quite elevated to start the long term. While activity will be diurnally enhanced, the upper level weakness will allow PoPs to remain Wednesday night into Thursday, before once again becoming fairly high through Thursday afternoon. Forecast diverges a bit on Friday with GFS/ECMWF handling the upper low differently. GFS continues retrograding the ULL into W TX while the ECMWF slowly nudges it eastward from the ArkLaTex towards the E CONUS trough. As a result, ECMWF comes in a little wetter than the GFS, but in both cases enough weakness/moisture to result in at least diurnally enhanced PoPs. In the forecast, stuck with the NBM which yielded higher than climo diurnal activity. For some good news, there may finally be some signs of relief on the horizon from the persistent wet pattern... By the weekend, ridging slowly starts to increase leading to more convective suppression and more typical low-end/isolated PoPs. While still some uncertainty, could see this last into the following week as well. To that end, the CPC 6-10 and 8-14 day outlook both indicate higher probabilities (~40% chance) of conditions drier than climatological normals. 50 MARINE...The subtropical ridge will remain stretched from the Atlantic into the northern gulf coast through the period. This will keep a generally light and onshore flow in place through the period. Gusty winds may occur in showers and storms that are forecast through the week. && .PRELIMINARY POINT TEMPS/POPS... AEX 76 90 72 88 / 30 80 80 70 LCH 77 91 74 88 / 10 80 90 90 LFT 76 90 74 87 / 20 90 90 90 BPT 76 92 73 88 / 10 60 90 90 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
615 PM CDT Sun Jul 18 2021 .SHORT TERM... (Through Late Monday Night) Issued at 241 PM CDT Sun Jul 18 2021 Currently, the MCV responsible for last night`s rain is approaching the confluence of the Mississippi and Ohio Rivers, and the front from late last week is roughly along the Missouri- Arkansas line. Isolated to scattered convection this afternoon will be associated with the MCV and residual surface moisture behind the front mainly across southeastern Missouri where SBCAPE is around 1,500 J/kg per SPC mesoanalysis. A shortwave noted in water vapor imagery over the Middle Mississippi Valley will continue its southward movement, bringing the low chance for isolated convection over our Illinois counties this afternoon. Lapse rates remain very poor area wide, and there is a subtle warm nose around 600 mb per RAP sounding analysis, so convection will be limited to mostly showers, though I can`t rule out a rumble of thunder. Convection will die off as instability wanes near sunset, and tonight looks dry across the CWA. Tomorrow, the shortwave will continue its path southward and phase with another shortwave currently over the Plains. These upper-level features and their associated upper-level support will be moving out of the CWA during peak heating, limiting any convective potential to far southwestern and southern portions of the CWA. Here, CAMs have widely scattered convection where moisture is deeper and roughly 1,500 J/kg of MUCAPE is forecast, so I have enough confidence to maintain a slight chance of isolated showers during peak heating in this area. Lapse rates continue to look poor, and some model soundings show a bit of a warm nose around 600 mb, so I expect updrafts to remain weak, but I can`t rule out a shower or two overachieving and producing a couple lightning strikes. Elmore .LONG TERM... (Tuesday through Next Sunday) Issued at 241 PM CDT Sun Jul 18 2021 EXTENDED Our relatively calm weather will continue through the first portion of the extended period, as the CWA remains under northwesterly flow aloft and a surface high sits over the Midwest. On Wednesday, the ridge over the western U.S. will begin to build eastward, and in response, the surface high will begin to shift eastward as well. This eastward shift in the surface high will allow for southerly low-level flow to return to the Middle Mississippi Valley late Wednesday into Thursday, allowing for warm, moist air to begin advecting into the CWA. This transition will be marked by temperatures climbing above climatological normals through the end of the extended period and a return of higher humidity. Ensemble guidance still differs in the extent of eastward progress the ridge makes later this week. More eastward movement would lead to temperatures warming a couple of degrees more and a decrease in rain chances, while a less eastward extent would lead to temperatures not getting quite as warm and greater rain chances due to shortwaves riding the eastern periphery of the ridge. Currently, 3 of the 4 ensemble clusters per WPC guidance support the second solution to some degree, and the current forecast represents somewhat of an upper-bounds to that solution. All that being said, the end of this upcoming week and next weekend will still likely be hot and humid - a notable difference from this current weekend. Elmore && .AVIATION... (For the 00z TAFs through 00z Monday Evening) Issued at 615 PM CDT Sun Jul 18 2021 VFR conditions are expected through much of the period at all terminals. The exception to this will be at COU and JEF where a brief period of MVFR stratus is expected early Monday morning. Confidence in the MVFR stratus materializing has decreased some from the previous forecast, but will maintain it for now and will re-evaluate with the 06Z issuance. Otherwise, VFR conditions are expected at all sites through the period. Cannot rule out some light fog at KSUS Monday morning or even a light shower at any site tonight, but these threats are too low to include any mention at this time. Deitsch && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
739 PM EDT Sun Jul 18 2021 .SHORT TERM...(This evening through Monday) Issued at 340 PM EDT SUN JUL 18 2021 Widespread smoke associated with the wildfires in Ontario and Manitoba has been the most exciting thing over our region today. This is producing haze over much of the region. So far observation sites haven`t registered any visibility reductions, so its been hard to say how much dinural mixing may be creating some smokey smells at the surface. HRRR Smoke product continues to suggest some smoke could mix down this afternoon, mainly in the interior west. Daytime highs so far have climbed into the 80s for most. The exceptions are along Lake Superior, mainly east of Marquette and up in the northern tip of the Keweenaw. Given the lake breeze off Superior didn`t result in much of a temperature change, I expect even the lakeside communities could experience rising temperatures for the next few hours. The reason today has been warm and relatively uneventful is a surface high positioned over Lake Michigan/Wisconsin and upper level ridge emanating out Rockies extending into Ontario/Quebec. As we move through tonight and into tomorrow, expect the high to sink south as a cold front approaches the region late tomorrow evening. Light gradient flow in the eastern UP will allow for lake breezes to push well inland. MLCAPE looks to climb to near 1000 j/kg near the boundary, which would be enough for shower and thunderstorms to pop up, mainly in Delta and Schoolcraft. Shear looks weak so strong to severe storms are not expected at this time. Southwest winds over the western parts of Lake Superior and in the Keweenaw are expected to increase soon after sunrise tomorrow. Some models suggest 925 mb winds could approach 25 to 30mph in some places. Given mixing during the day tomorrow, the Keweenaw may have some gusty winds reach the surface. Its also going to be warm tomorrow. I`m a little uncertain how much shortwave radiation will be prevented from warming the lower atmosphere due to the continued smoke aloft, but generally upper 80s with some low 90s are possible, particularly away from the lakeshores. Coupled with the dry airmass and the lack of rain in recent memory, some elevated fire weather conditions may be possible from northern Houghton County northward. .LONG TERM...(Monday night through Sunday) Issued at 357 PM EDT SUN JUL 18 2021 The overall large-scale pattern for next week will feature anomalously strong ridging centered over the Rockies and downstream troughing into eastern Canada and the northeast U.S. The Upper Great Lakes will remain on the northeastern edge of the ridge beneath persistent NW flow aloft between these large scale features. A few waves digging southeastward through the flow this week will lead to lowering heights and temps cooling into midweek behind Mon night`s cold fropa, but then it appears ridging and warmer temps will tend to dominate late week. Monday night, a strong cold front will be approaching our area from the north. With the models trending slower with the fropa and given that dewpoints Monday afternoon will likely mix out ahead of the front, it would appear instability may be limited for thunderstorms. Even the previously more bullish moisture-biased NAM soundings now show very limited instability even for showers, let alone thunderstorms Mon night. Suspect more isolated to scattered coverage of showers along the front and will trend PoPs accordingly. Tuesday, behind the front, cloud cover may be slow to clear in the morning. Many models hold on to low stratus in the typical north wind upslope areas in Marquette County. This cloud cover along with a steady north wind and 850 mb temps dropping to around 10-12 C behind the front should hold temps down in the mid 60s to low 70s for highs. Could even see temps struggle to get out of the low 60s for highs in parts of Marquette County if cloud cover hangs on longer than models suggest - which it often does under northerly winds. Still a decent amount of uncertainty with regards to temps on Wednesday, although other than the 12Z NAM, models generally have trended cooler for Wednesday. So, did follow the lead of mid shift and lowered max temps a bit blo NBM guidance...generally in the lower to mid 70s. The 12Z NAM also indicates quicker advancement of the warm front and associated light rain into the area on Wednesday, but this solution too seems to be an outlier compared to the drier GFS and Canadian solutions. Looks like the next best chance of rain will be Wednesday night when the next shortwave drops down in the NW flow aloft and its associated surface cold front drop southeastward across the Upper Great Lakes. The 12Z GFS and Canadian and 00Z EMCWF show a distinct precip signal late Wednesday night. Therefore, will maintain the likely PoPs for Wednesday night. Similar to Monday night, thunderstorm chances may be limited by questionable moisture return and instability ahead of the wave. However, models do show stronger shear with this wave, which could perhaps end up bolstering thunderstorm chances. Showers and a few storms will probably linger into Thursday as the frontal boundary continues to sag through the area. By the end of the week, the warm Western CONUS ridge starts to nose into the area, leading to another warm-up. Although there is still some spread in the ensemble guidance, the lion`s share of members take 850 mb temps back up into the 15-18 C range which means more highs in the 80s for most of the area Friday into the weekend. 12Z operational models do hint at a few ridge-runner shortwaves moving through the Upper Lakes which could maybe produce a few rounds of convection over the area next weekend, so this will be something to watch on subsequent model runs. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 739 PM EDT SUN JUL 18 2021 VFR conditions will prevail at all sites as the region remains under the influence of high pressure and a dry airmass. Winds will increase at KCMX ahead of an approaching cold front. A fairly thick layer of smoke associated with wildfires upstream is expected to remain over the region through this period. However, vsby is expected to remain VFR with only a low probability of brief MVFR conditions. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 340 PM EDT SUN JUL 18 2021 Light winds are expected to continue tonight across the lake as surface high continues to dominate the region. This high will sink south tomorrow as a 925mb 25 to 30 knot LLJ moves into the western part of the lake. I`m skeptical about how much of these southwest winds will mix to the surface given the stable lower atmosphere, but high reporting platforms could end up observing some gustier conditions. Cold front will move through tomorrow night. Thunderstorms will be possible ahead of and along this boundary. Afterwards tomorrow night, north to northeast winds are expected to be 20 to 25 knots. By late Tuesday, winds look to return to 20 knots or less across the lake and remain there through the rest of the week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JP LONG TERM...Voss AVIATION...JLB MARINE...JP
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 250 PM CDT Sun Jul 18 2021 From the comings and goings of co-workers, the undersized window and ObsMonitor3.3.1, it seems like it`s a pleasant day outside. Current temps show numbers within a couple of degrees on either side of 80 and wind speeds running mostly under 10 knots out of the southeast. The sun is being filtered out by two distinct cloud decks... a broken set of cumulus at about 3000 feet caught up in the low level SE winds and some stratus blowing off the top of the convection in north central Kansas that`s working in the opposite direction. Some significant haze from western wildfire smoke across most of Nebraska today, but generally west of this CWA. This gradient of vertically integrated smoke will continue for Monday with bluest skies east of the Missouri River. The 12Z run of the HRRR reveals a denser plume of smoke pushing overhead on Tuesday afternoon. Expect some patchy fog development overnight tonight as a nose of surface high pressure helps bring the winds to a near standstill. Best chances of this fog will be along the Kansas state line, western Iowa, the easternmost tier of counties in the state of Nebraska, and generally where there`s plenty of corn. Monday morning convection has been progressively further west on latest guidance and have removed isolated POPs as a result. This makes the spotty heavy rain on Saturday all the more important as the forecast will be dry through the work week... with only slight chances of thundershowers Friday night and perhaps the weekend. Under the 500HPa ridge, southerly winds will help temps slowly rise over the course of the week. Tuesday will be relegated to the mid-80s. Expect the entirety of the area to manage 90F+ by Thursday with mid-90s to near 100F by Friday. Heat indices on both Friday and Saturday may push 105 and trigger a heat advisory. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 601 PM CDT Sun Jul 18 2021 Light southeasterly winds are expected to prevail through the forecast period. A diurnally driven cumulus field may also develop by midday tomorrow and bring CIGs down to around 4 kft. During the overnight hours, subsidence aloft should reinforce the nocturnal BL inversion. This coupled with weak moisture advection out of the southeast and radiational cooling will help bring the boundary layer to near saturation by early morning. As such, patchy fog is possible across parts of east central Nebraska and west central Iowa. This may result in a brief period of MVFR conditions tomorrow morning at KOMA, but should return to VFR by a couple hours after sunrise. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Nicolaisen AVIATION...Mead
Area Forecast Discussion
National Weather Service Spokane WA
428 PM PDT Sun Jul 18 2021 .SYNOPSIS... Wildfire smoke will likely continue to plague the region with areas of degraded air quality especially around the Methow Valley and Lewiston area. There will be an increasing chance for thunderstorms over the eastern third of Washington and North Idaho Monday Night through Wednesday. Breezy and dry conditions next week will also contribute to elevated fire concerns for ongoing fires or any new ignitions that occur. && .DISCUSSION... ...Critical Fire Weather Conditions possible Monday Night through Wednesday... Tonight through Wednesday: Models continue to show a broad southwest flow over the region between a closed low off the central BC coast and a ridge over the southwest US. Increased monsoonal moisture and a pair of mid level waves tracking through will provide two opportunities for thunderstorms over the eastern third of Washington into the Idaho Panhandle...mainly east of a line from Ritzville to Colville. The first wave arrives late Monday Night into Tuesday morning. Several of the CAM`s models show some elevated convection developing but lightning should be isolated in coverage with 700-500mb MU CAPE of only 100-300 J/KG. Still given the very dry fuels any lightning is a concern for new fire starts. The second wave arrives Tuesday Night into Wednesday morning. This one has a bit more instability to work with, and stronger forcing as the upper low off the Central BC coast begins to push inland. This raises concerns for more lightning with scattered coverage possible over SE Washington into the ID Panhandle. Despite the increased monsoon moisture, storms that develop are expected to be elevated and fast moving, only putting down brief rain. Thus new fire starts are a big concern and a Fire Weather Watch has been issued from the Spokane area down to the Palouse east into the Idaho Panhandle where confidence is highest of thunderstorm development. Besides thunderstorms starting new fires, also keeping a close eye on winds and low relative humidity. A tight cross-Cascade pressure gradient will promote breezy winds through the Cascade gaps Monday evening. Tuesday gradients tighten a little further with breezy winds expanding to include the Columbia Basin and Okanogan Valley. Wednesday as the trough pushes in winds may increase a bit more. Confidence is not high enough at this time of critical wind/rh thresholds being met for a Fire Weather Watch, but conditions will be elevated and could affect any new or existing fires. Lastly, smoke will continue to impact air quality at times near fires especially the Methow Valley and around Lewiston. Higher level smoke from fires over Oregon will continue to track into Eastern WA and North Idaho producing hazy skies. JW Thursday through Saturday: After the cold front passage Wednesday, a notably drier air mass with a dirty ridge moves into the area. Minimum RH values will get down into the lower teens with locally lower values, and combined with somewhat breezy afternoons from diurnal mixing, fire concerns will stay elevated Thursday and Friday. Temperatures Thursday will be slightly cooler than Wednesday, only reaching the mid 80s for much of the area. Things warm back up to the upper 80s and low 90s Friday. The rest of the weekend, RH values are expected to increase slightly, with temperatures remaining in the upper 80s and low 90s. RC && .AVIATION... 00Z TAFS: High elevation smoke and haze will be found across the northern mountains, Idaho Panhandle, and southeast Washington due to ongoing fires. HRRR smoke models show this to persist through the period. Areas of low level smoke may limit visibilities with marginal VFR conditions near Lewiston as well as Winthrop under light winds. Scattered high clouds start to move north Monday morning. Some convection is possible across north central ID Monday afternoon which could lead to occasional southeast gusts to 15 mph near Lewiston and Pullman. rfox && .PRELIMINARY POINT TEMPS/POPS... Spokane 63 97 66 91 61 88 / 0 0 10 20 20 20 Coeur d`Alene 65 96 64 90 59 87 / 0 0 10 20 20 30 Pullman 60 91 62 86 56 83 / 0 0 20 20 30 30 Lewiston 68 100 72 96 67 92 / 0 0 20 20 30 30 Colville 55 98 58 93 53 89 / 0 0 0 10 20 20 Sandpoint 55 94 62 88 58 86 / 0 0 10 20 20 30 Kellogg 59 93 67 86 64 86 / 0 10 10 20 30 30 Moses Lake 60 97 62 93 57 89 / 0 0 0 0 0 0 Wenatchee 66 97 67 91 62 87 / 0 0 0 0 0 0 Omak 66 100 66 96 61 91 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...Fire Weather Watch from late Monday night through Wednesday morning for Northern and Central Idaho Panhandle (Zone 101). WA...Fire Weather Watch from late Monday night through Wednesday morning for East Washington Palouse and Spokane Area (Zone 674). && $$
Area Forecast Discussion
National Weather Service Phoenix AZ
420 PM MST Sun Jul 18 2021 .UPDATE... Updated Aviation && .SYNOPSIS... Abundant monsoon moisture will continue to bring daily chances for at least isolated to scattered showers and thunderstorms across south-central and eastern Arizona with a tendency to favor the higher terrain of eastern Arizona, especially for the first half of the week. Isolated storms are also possible over southwest Arizona and southeast California. Near to below normal highs expected for the first half of the week, then below normal by late in the week. More scattered to widespread storms are possible for the second half of next week and into the weekend. Storms will be capable of producing both locally heavy rain, strong winds, and blowing dust. && .DISCUSSION... The H5 RAP and SPC mesoscale analysis shows the UL high centered near the NV-CO border, barely just N of 4-Corners area. Fairly deep and moist S-SE-E flow aloft was present from below H7 to H5 to H3. A large zone of elevated H7-H5 mean RH>=70 (& 80-90)% extended from N MX, SE-S-Cent AZ into W-NW AZ. SPC mesoscale analysis showed elevated PW ranging from 1.7-1.8 S and W of Phoenix to near 1.5 near Phoenix which was ~0.4 too low compared to the 12Z Phx sounding which had over 1.85. The 12Z Phx sounding also showed small caps in the mid levels and fcst sfc CAPE of 1389 j/kg. The Phx 12Z also featured above normal mean W of 12.5 g/kg, up from 11.6 gm/kg shown on the 00Z sounding. SPC confirmed fairly widespread elevated CAPE (& CIN) from the upper 100s to low thousands j/kg with more elevated forecast values into the 2-3K j/kg forecast for the afternoon along the outskirts and surrounding the CWA. 8 mid to late morning ACARS showed mean MUCAPE up to 1276 j/kg. Sunday GOES imagery showed abundant mid-upper blow-off clouds associated with a weak PVA disturbance and and an area of associated modest thundershowers SE of Phx earlier today. These thundershowers moved into N Pinal and the SSE CWA including far SE Phx outskirts this morning with spotty modest rainfall. By midday METSAT showed cloudy-mostly cloudy conditions and an MCV in the W-central CWA and W half of the Phx valley with an area of light rain returns, while mostly clear skies, and stronger heating, dominated the E half of Phoenix and much of the E CWA. The expanding UL ridge was driving small disturbances and supporting the very moist and unstable conditions across the high country, while igniting early afternoon Mogollon Rim convection/thunderstorms. The HREF and later runs of the HRRR support E AZ isolated to occasionally scattered convection moving into S. Gila Cty for the late afternoon and early evening for a few hours before decaying as they edge west. Then a second late night round of convection is depicted that could give Phx or the N-E Valley a glancing blow of late night storms tonight. It is also very bullish on a very pronounced E-NE outflow moving through Phoenix late tonight and even possibly holding together through La Paz county early this morning. For the first half of the week the UL high moves very little. As a result very moist and unstable conditions and diurnal convection will persist through the region, especially for the higher terrain with its orographic and upslope advantages. As a result the preferred NBM POPs remain significant through the period near 30-40% around Phoenix with slightly lower POPs even supported out W across SW AZ and SE CA. Storms will be capable of producing both locally heavy rain, strong winds, and blowing dust. Clusters and ensembles are still signaling possible upticks in moisture for the second half of the week and into the weekend. This may be the result of a larger easterly wave disturbance moving in from Texas into N-NW MX. Higher end WPC QPF has emerged along with increased chances for scattered flash flooding. Max temperatures appear to become quite moderated in and around Phoenix as below normal highs look to favor the upper 90s by late this week and possibly even the weekend. && .AVIATION...Updated at 2320Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Winds should become more solidly SW across the metro early this evening with storms building over mountains. Although NBM shows 30% chance of storms and HREF output indicates a 40% chance of outflow winds in excess of 30 kt, in situ observations show an environment not very good for thunderstorm maintenance. Recent HRRR model runs have backed off the forecast of storms in the metro while also dialing back outflows and wind speeds. Kept a mention of an outflow boundary and VCSH in this TAF package, though with low confidence. While stronger wind gusts are more uncertain, some measure of easterly winds should take hold by late evening. There is even a chance that storms in far SW AZ push a reinforcing SE outflow into the metro well after midnight. It is also possible (20% chance) a few elevated showers develop into the metro early Monday morning. Otherwise, winds should switch to west by early Monday afternoon with the potential for a SE outflow Monday evening. Southeast California/Southwest Arizona including KIPL and KBLH: Under occasional passing mid/high clouds, southerly winds will be favored at KBLH while E/SE directions at KIPL. Speeds will remain fairly steady around 10kt with a few higher gusts. Some enhanced winds due to long traveling outflows may be possible Monday morning along with localized haze resulting from thick moisture increases. NBM output shows 30% chance of morning showers at KBLH and 20% at KIPL, but have not included any mention in this TAF package. && .FIRE WEATHER... Wednesday through Sunday: Temperatures will generally be near to slightly below seasonal averages through the period as monsoonal moisture remains in place over the region. Storm activity is anticipated to spread as far west as southeast California with most storms having good potential for wetting rain (0.10" or more). Threats from storms will continue to involve locally heavy rainfall and flash flooding along with strong outflow winds and localized downbursts within storms. Significant flooding may be experienced on previously burned areas of Gila County, particularly during the second half of the week. Min RH levels are expected to remain in the 20-30% range most areas (30-50% higher terrain of south- central AZ). Max RH levels will be 35-60% most places (60-90% higher terrain of south- central AZ). Apart from thunderstorms, winds will favor familiar diurnal patterns. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Sawtelle AVIATION...18 FIRE WEATHER...Sawtelle/Kuhlman
Area Forecast Discussion
National Weather Service Pueblo CO
253 PM MDT Sun Jul 18 2021 .SHORT TERM...(This evening through Monday) Issued at 249 PM MDT Sun Jul 18 2021 Area of strong to severe t-storms moving southward along the KS border this afternoon, as MCV drops into central KS and associated outflow boundary pushes southwestward into CO. CAPE values running in the 2000-3000 j/kg range ahead of these storms, while 0-6km shear has increased into the 30-35 kt range as low level winds turn more sely under the wrn edge of the upper level jet streak over nwrn KS. Expect severe storms to continue to move s-sw over Kiowa/Baca/Prowers counties through 00z given amount of instability and developing gust front, with most CAMs, especially the HRRR and RAP, not helping the forecast much, as they have poorly modeled both the instability and extent/strength of convection so far today. Farther west, weak subsidence has limited convection to mostly weak/isolated activity over the mountains, and as a result, cut back pops to mainly isolated into the evening hrs given rather un- impressive satellite/radar trends so far. Expect eastern plains storms to slide south and east of the area by late evening, leaving much of the region free of convection by midnight. On Monday, drying mid-levels and continued subsidence suggest very sparse afternoon convection over the mountains and valleys once again, while n-ne steering currents should keep any activity away from the I-25 corridor. Plains slightly more questionable, as plentiful surface instability lingers near the KS border, with potential for left-over outflows to force some very isolated activity late in the day. Not enough confidence in this scenario to include any pops yet, but mesoscale details need to be monitored overnight and Mon morning for potential changes. Little change expected in high temps, as typical mid-July heat continues. .LONG TERM...(Monday night through Sunday) Issued at 249 PM MDT Sun Jul 18 2021 ...Forecast Key Points... - Pattern shift shunts moisture westward. - Warming trend east of Continental Divide. - Recycling the moisture under the heat dome. Well well well, how the turntables have turned. Going from a non- soon the past couple of summers to a monsoon out west is fantastic and the upcoming week, or next two, prove this the case. Areas east of the Continental Divide will see fewer chances for showers and storms, though not an entirely dry forecast. Tuesday...A few isolated to scattered showers and storms around, mostly the higher terrain, east of the Divide. West of the Divide, a good dousing of moisture expected for sure. Wednesday...Probably the most widespread active day in this period. Remember the game `ring around the rosey`? This is like `ring around the ridge-y` where in this case the rain comes falling down and likely heavy at times, especially from I-25 westward. Upper level flow will be more north to south so expect slow moving storms to pop and then drift southward during the afternoon and evening hours as we get a brief boost in monsoonal moisture from the west. Temperatures look to top out a few degrees above mid-July averages as well. Thursday - Saturday...General trend is more active west and less active east, with building heat. It really is hard to discern a totally dry day across the region, except for maybe the far eastern plains the later half of the work week. Moisture is around, though not a lot east of the Divide (again), and the expanding ridge back to the west would keep a lot of us on the drier side, and yet we`re still carrying what would equate to a coin-flip for storm chances. Confidence is just not there in this pattern to say yay or nay for storms, or not. Temperatures again a few degrees above averages. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 249 PM MDT Sun Jul 18 2021 VFR conditions at all taf sites the next 24 hrs. Low risk of a vcsh or vcts at KALS until 02z, while activity will likely stay over the higher terrain west of KPUB and KCOS. Main impact from any storms will be brief rainfall and gusty outflow winds. On Monday, thunderstorm chances will continue to trend downward, with only isolated convection over the mountains. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...PETERSEN LONG TERM...HEAVENER AVIATION...PETERSEN