Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/24/22


Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
910 PM CDT Tue Aug 23 2022 .UPDATE... Issued at 902 PM CDT Tue Aug 23 2022 Continuing to watch an area of sub-severe thunderstorms across south central ND, and additional areas of isolated activity southward across central SD. Outflow-driven development is noted coming southward out of ND and into north central SD. Adjusted POPs earlier this evening to account for anticipation of this which the HRRR seemed to pick up on. Will have to make some more adjustments to POPs in a bit to account for recent radar trends. Otherwise, it would appear CAMs continue to suggest best rainfall chances overnight remain across central SD, maybe pushing as far east as the James River. Parameters suggest sub-severe with maybe some brief small hail - shear is very limited. Overnight lows look ok for the time being and no changes there. && .SHORT TERM...(This Evening through Wednesday Afternoon) Issued at 334 PM CDT Tue Aug 23 2022 Afternoon showers have already made their appearance over central South Dakota. The intensity remains low at this time, with no lightning being detected. This will probably change after 21Z, with at least a few thunderstorms in the area. We`re still not expecting anything other than some lightning and potentially gusty winds with the strongest storms. Currently, we`re stuck in northwesterly flow aloft with subtle embedded waves. A 500mb low resides over northern WA/southern British Columbia, with the main low over far northeast Canada. Over the period we`ll experience ridging late Thursday afternoon into Thursday evening in advance of the nearing low to our northwest. At the surface, there is a low over south central SD. It will only slowly shift east into far southeastern SD and southern MN by midday Wednesday as cooler air sinks in from the north. The low will continue across IA Wednesday night as a large ridge of high pressure moves in from Canada. Highs Wednesday will be in the 80s, or about 5 degrees less than today. After the slight to low chance pops Wednesday, the chance of showers should diminish to the slight chance category Wednesday night. .LONG TERM...(Wednesday Evening through Tuesday) Issued at 334 PM CDT Tue Aug 23 2022 Models are overall quite consistent with a cutoff low over the northwest CONUS and weak ridging over the northern plains Thursday into Friday. It isn`t until the weekend that the pattern begins to shift and the low kicks out, becoming a low amplitude trough as it moves east across the northern plains. As such, POPs increase for the weekend, although with the generally weak flow aloft and low to moderate CAPE, the organized severe threat remains relatively low. Model consensus wanes after the weekend. While they all show variations of a brief ridge followed by another trough early next week, the trough/ridge amplitude and overall timing varies. 500 MB cluster analysis shows the Canadian members seem to trend toward a deeper trough scenario whereas the EC members cluster around a less amplitude more progressive flow by early next week. These differences lower forecast confidence and will play a major role in both the precipitation and temperature forecast in the out periods. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 635 PM CDT Tue Aug 23 2022 Terminals KABR,KATY,KPIR,KMBG VFR conditions are currently forecast for the TAF time period. There are isolated -SHRA/SHRA and even a couple -TSRA at times west of the Missouri River. Some of this activity may affect KPIR/KMBG into the early evening, so will include VC (vicinity) mention at this time. Will adjust TAF if it appears -TSRA/TSRA will affect a TAF site, but confidence is very low at this time. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...TMT SHORT TERM...KF LONG TERM...Serr AVIATION...TMT
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
959 PM CDT Tue Aug 23 2022 ...New UPDATE... .UPDATE... Issued at 945 PM CDT Tue Aug 23 2022 Isolated storms ongoing mid evening near Hondo and southeast of Eagle Pass are moving little. A localized flooding threat is possible in these locations. Coverage of convection should remain isolated over the next couple of hours, mainly over southern areas. 00Z CAM guidance coming in is becoming more interesting during the overnight and early morning hours. Several members (HRRR, ARW, FV3, NAM) are developing scattered showers and storms in an axis roughly from the Winter Garden region to the San Antonio metro area and east along the I-10 corridor, near the surface front and slightly sharpening 925mb shear axis. There is modest amounts of CAPE available, and given the 2-2.4" precipitable water values and slow southeast storm motions some pockets of locally heavy rainfall could occur. Of course this is conditional on the forcing being strong enough to generate convection. We have raised PoPs slightly through this region and will add a mention of locally heavy rainfall into the HWO for this region overnight and early Tuesday morning. && .SHORT TERM... (Tonight through Wednesday night) Issued at 158 PM CDT Tue Aug 23 2022 Latest SPC mesoanalysis places a stalled out frontal boundary from Eagle Pass to Hondo to Gonzales and up into Giddings. This boundary has been the focus for overrunning showers and isolated thunderstorms early this afternoon. While coverage and intensity haven`t been quite like yesterday`s convection, locally heavy rainfall and rates of 1-2" per hour are still possible through this evening. Have gone ahead and dropped the Flood Watch for all counties as hi-res guidance continues to point to the axis of heavy rain developing further south this evening, over the Winter Garden region and into portions of Corpus CWA. The HRRR has been consistent in developing a round of heavy rain over southern Maverick and Dimmit and sliding it northward late this evening, so flooding concerns are slightly higher in this region, and our latest forecast thoughts in terms of QPF echo this thinking. Some notable breaks in the overcast have been noted over the northern CWA into the Hill Country and expect that isolated to scattered showers and thunderstorms will develop through the afternoon and evening and shift southward through early to mid evening. There is the threat that locally heavy rainfall could lead to flooding across much of South-Central Texas, but widespread flooding is no longer a concern, hence canning the watch. Wednesday should be quieter with isolated to scattered showers and storms still a possibility, but more of the "garden variety", which is basically all you can ask for when in a drought. We`ll continue to take any rainfall we can get, with the active pattern that is expected to continue on into the long term. With all the cloud cover and increased moisture, surface dewpoints in the 70s, PWATs up over 1.5-2.0 inches, and now some actual soil moisture to work with, think that afternoon highs should remain in the mid to upper 80s and lower 90s both today and Wednesday. Nevertheless, even with increased cloud cover and lower temperatures, heat indices may creep up into the 100-105 range briefly, especially during the late afternoon hours where any sunshine manages to sneak in. One last thing: WPC ERO remains Marginal for much of South-Central Texas on Wednesday, so locally heavy rainfall does remain a threat, but like mentioned above, widespread flooding or flash flooding is not expected, and with our lengthy drought, most creaks, streams, tributaries, and lakes can handle quite a bit of water/drainage at this time. && .LONG TERM... (Thursday through Tuesday) Issued at 158 PM CDT Tue Aug 23 2022 The bad news first: Chances for widespread and significant rainfall in the long term are low, despite at least some POPs in the forecast in some areas for most periods. Coverage most days will be isolated to at best scattered, as there won`t be much large-scale forcing to speak of, height anomalies will have weakened, and PWATs will lower some, especially over the Hill Country. The good news: Daily high temperatures will remain near to below average Thursday through next Tuesday, and some areas will at least still see SOME additional rainfall. It just won`t be enough to lead to additional drought improvements. Not a whole lot of details we can add at this time. While the 12Z NAM depicts some heavy rain in our western counties during the day, it`s a bit of an outlier and guidance is a bit wide-ranging. Locally heavy rains do remain possible given PWATs still progged in the 2- 2.3" range over the southwest half of our area, and WPC continues to advertise a marginal risk for excessive rainfall. But forcing may be hard to come by with only a very diffuse temperature gradient leftover in the region. And even that will be gone by Friday and beyond, lowering chances for locally heavy rainfall further. While isolated afternoon rains are possible over the weekend, most locations will stay dry and it will likely be a pretty nice weekend for outdoor activities as long as you don`t mind humidity! Afternoon dew points will not do much mixing out over the next week or so, and as a result some locations could see heat indices approach and exceed 100 in the afternoons. && .AVIATION... (00Z TAFS) Issued at 700 PM CDT Tue Aug 23 2022 VFR conditions this evening with isolated SHRAs currently south and west of SAT. The forecast indicates a potential for isolated SHRAs continuing tonight across the region, possibly becoming widely scattered south of SAT. VFR conditions and light winds will prevail tonight. MVFR ceilings may develop near and north of a ERV-SAT-AUS line 12Z-17Z Wed. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 76 91 76 93 / 20 40 20 40 Austin Bergstrom Intl Airport 75 90 74 93 / 20 40 20 40 New Braunfels Muni Airport 75 92 74 94 / 40 50 30 50 Burnet Muni Airport 73 88 73 92 / 10 30 20 30 Del Rio Intl Airport 76 92 76 92 / 20 40 30 50 Georgetown Muni Airport 75 89 74 92 / 10 30 20 30 Hondo Muni Airport 75 92 74 91 / 40 40 30 50 San Marcos Muni Airport 75 90 74 93 / 30 40 30 40 La Grange - Fayette Regional 76 90 74 93 / 30 40 30 40 San Antonio Intl Airport 75 91 75 91 / 40 50 30 50 Stinson Muni Airport 75 93 75 93 / 40 50 30 50 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...Morris Long-Term...KCW Aviation...76
Area Forecast Discussion
National Weather Service Pocatello ID
128 PM MDT Tue Aug 23 2022 .SHORT TERM (Tonight - Wednesday)... Afternoon satellite imagery shows less CU development over the area today. This was expected with slightly drier airmass in place and because of this, expecting afternoon/evening shower and storm coverage to be much more limited. RAP analysis shows PWATs currently running around 0.6-0.7 inches across the region. Hi-res CAMs keep much of the precip outside of our area into Montana and central Wyoming where slightly deeper moisture is present. Nevertheless, there remains just enough moisture and model support an isolated chance for convection later today in the central mountains and eastern highlands, mainly the latter. This will be short-lived though as increasing moisture advection is expected for tomorrow, once again, thus allowing for higher PoPs for the day on Wednesday. Hi-res model guidance is already supportive of this thinking. Thunderstorm coverage looks to remain on the isolated side, for fire weather concerns, but things remain in flux. Daily temperatures will run slightly higher than normal over the next couple of days and winds will generally be light outside of convection, increasing a bit beginning tomorrow. McKaughan .LONG TERM (Thursday through next Tuesday)... An upper low will linger over northern ID/northwestern MT on Thursday. This will trigger some isolated to scattered afternoon thunderstorms. Operational models are in fair agreement with the positioning of the low as it pushes slowly eastward. By Friday, the low will accelerate eastward as another trough swings in from the west. Friday should be a relatively dry day with only some isolated convection expected along the WY and MT borders. With the upstream trough digging into the PAC NW on Saturday, we`ll see the surface pressure gradient tighten up. So will expect to see some fairly breezy condition across the region on Saturday. Even as the low dips into northern Idaho Saturday evening, it will have little moisture to work with, so Saturday may only see isolated thunderstorms confined to the Island Park area. The 12Z GFS is suggesting a deeper trough than other long-term models for Saturday night/Sunday. Ensemble clusters show some uncertainty beyond Saturday. Some CMC ensemble members are mirroring the operational 00Z Canadian model reflecting a deep upper low over Idaho with ridging is seen on the GFS and ECMWF models. The 12Z Canadian model, however, seems to have backed off the deep low in favor of a fairly weak trough. Overall, the extended periods look to be hot and dry. Hinsberger && .AVIATION... VFR to prevail across the area outside of any showers and storms. Chances for this look much lower today compared to previous days. Best chance will be at KDIJ where VCTS continues in the forecast later this afternoon and into the evening. The rest of the terminals will likely stay dry based on latest hi-res model runs but kept VCSH mention at KIDA for continuity and for the very outside chance of a shower here. Otherwise light and variable winds are expected overnight and to start the day Wednesday. Just beyond the current forecast period, winds may be a tad higher tomorrow compared to the last few days but still less than 15 kts with afternoon showers and storms likely to make another appearance across the region later tomorrow. McKaughan && .FIRE WEATHER... Much drier weather is expected today compared to yesterday. Isolated thunderstorms may develop this afternoon along the MT and WY borders. There is still an upper low lingering over north central WA, but most of the moisture has shifted to the east. Monsoon moisture will surge back into the area tomorrow with the low slowly moving into eastern WA. Isolated thunderstorms will once again develop over the Central Mountains and Eastern Highlands. On Thursday, the low will continue to slowly progress eastward and will be positioned over northern ID/northwestern MT by the afternoon. Isolated to scattered thunderstorms are expected generally in the same areas as Wednesday. As the low exits to the east Friday, we should see drier and more stable conditions, with isolated convection mainly along the MT and WY borders. Heading into the weekend, much of southeast Idaho will be dry, but we could see winds pushing us close to critical fire weather conditions as the surface pressure gradient tightens. The limiting factor will be humidity, and we may see pockets of sub-15% humidity in the valleys. Hot and dry weather is expected to build back into the area early next week as ridging amplifies over the West. Hinsberger && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Phoenix AZ
150 PM MST Tue Aug 23 2022 .SYNOPSIS... A significant uptrend in thunderstorm coverage is expected today over Arizona which in turn will make areas of strong to severe winds and blowing dust, along with localized brief heavy rain, more likely late this afternoon and tonight. Rain chances increase Wednesday and expand into southeast California. A gradual downtrend in storm chances takes place during the latter half of the week and over the weekend. Highs today will be a little warmer than yesterday then a bit cooler Wednesday. Anticipate highs being a bit below normal the rest of the week before a warming trend begins Monday. && .DISCUSSION... The synoptic setup today is supportive for Rim-to-Valley storms during the afternoon and evening with modest northeasterly mid- level flow (~15 kt 500 mb winds). The 12Z sounding from Phoenix this morning showed some moistening of the boundary layer and the strong capping inversion on the boundary layer has weakened over the past 24 hours. Of note as well on the 12Z sounding is the strong southwesterly anvil-level winds. This will push the thunderstorm anvils off to the northeast, which is already being seen with storms along the Rim. Mid-level lapse rates are still modest, around 7 C/km, and CAPE is pretty high (MUCAPE currently analyzed around 2000-3000 J/kg), supportive of explosive updrafts. Additionally, there was some considerable mid-level drying shown in the morning sounding, which will result in some dry air entrainment into the storms, supporting stronger downdrafts. DCAPE is high this afternoon with magnitudes analyzed around 1000-1500 J/kg across the lower deserts. So, damaging downburst wind gusts will be a threat today. A weak but noticeable vort max is evident over southern AZ this afternoon on WV satellite and could further aide ascent through the area. Forecast soundings support further erosion of the capping layer over the lower deserts through the rest of the afternoon with continued heating and mixing, but a good source of lift will likely still be need to invigorate storm development. Fortunately, with the strong DCAPE environment, outflows are likely to push into the lower deserts and could push all the way to the CO River. Most hi- res models develop storms off of these outflows this afternoon and evening, but coverage of storms could be a little spotty with the lower moisture content. So, not everyone will experience storms today, but nearly everyone should be able to "see" the storms. With the parameters presented in the first paragraph, any storm that develops over the lower deserts today will be capable of producing strong to severe wind gusts, which could also generate areas or widespread blowing dust depending on source region. HREF probabilities for 35+ mph winds are around 50-70% for much of southern AZ with ~10% odds of greater than 58 mph. Nitpicking some of the individual hi-res model runs, localized wind gusts up to 70-75 mph cannot be ruled out. With the lower moisture content and potential pulse nature of the storms, flash flooding is not as great of a risk, but storms will be capable of rain rates up to 1-2"/hr and flash flooding will still be possible, especially with any storm that lingers over an area or multiple storms hit the same area. While most of the storms are expected to descend off the AZ high terrain north and east of Phoenix, isolated development in a few other common terrain spots will be possible, including the Table Top Mesa area, the Kofas, and Joshua Tree NP. Most activity should diminish this evening, however, lingering mid-level ACCAS convection cannot be ruled out overnight, especially with any lingering meso-circulations (MCVs). Tomorrow, Wednesday, following some slight increases in moisture and possibly some preconditioning from today`s activity, could be even more active. NBM has widespread PoPs of 30-40% or higher across southern AZ and southeast CA. Recent runs of the HRRR are really quite impressive with scattered to widespread strong thunderstorms. There are a few changes from today into tomorrow expected, albeit small. Synoptically, mid-level steering flow is expected to become a touch weaker and shift more easterly to southeasterly as the anticyclone over NV slides east with a shortwave moving into north CA. With this alone there may be better motion and convergence of convection in the western deserts toward western AZ and the CO river through the afternoon and evening with outflow collisions driving a lot of the storm clustering. The wind threat is not expected to be quite as high as today, but locally strong to severe gusts will still be possible. The flash flood threat will be higher tomorrow with the slight increase in moisture, slower steering flow, and clustering of storms. Thursday through Monday, ensemble data continue to show a gradual west to east decline of PoPs as the primary anticyclonic flow becomes centered to our south for a less favorable flow regime (deeper westerly and drier flow) over our forecast area. There are some model hints of an uptick in PoPs on one of the days during the latter half of the week. That would be plausible if a short wave within the westerly flow moved through while we still have decent moisture left. By next Monday though, storm chances look pretty meager. Moderate HeatRisk will continue the next couple of days for much of southeast CA while south-central AZ sees temperatures a few degrees below normal. Moderate HeatRisk becomes more widespread by early next week. && .AVIATION...Updated 1751Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Things will start out quiet with easterly winds with speeds aob 7 kts prevailing through the rest of the morning. A westerly wind shift is anticipated by early afternoon with speeds to around 10 kts. Attention will then turn to thunderstorm activity expected to develop across the higher terrain and descend into the valley floor from the northeast during the 00Z-02Z timeframe with a 50-70% chance of winds exceeding 30 kts and a 10% chance of winds exceeding 50 kts. Blowing dust will also be a threat, but chances for dense blowing dust appear to be less (20-30%) given the most likely northeasterly wind direction and recent rainfall reducing the amount of dust that can be picked up by the winds. In addition to the strong wind threat, localized heavy rainfall resulting in very brief MVFR or lower conditions is also possible if a storm directly impacts an area terminal. Mostly clear skies will predominate through the morning hours with increasing SCT- BKN coverage by mid to late afternoon. Once the storms move thru, expecting lighter northeasterly-easterly winds to prevail, the switching to more typical southeasterly by late evening. Easterly winds to continue thru Wednesday morning, then once again switch to westerly during the afternoon. Another good chance (40-60%) exists for t-storm again during the late afternoon/early evening on Wednesday. A better chance for heavy rain appears to be the case for storms on Wednesday, but still a good chance (50-70%) for winds over 30 kts with the most likely direction for storms to move into the Phoenix area being from the northeast. Southeast California/Southwest Arizona including KIPL and KBLH: No aviation weather concerns expected through the period at KIPL with winds mainly from a southeasterly component, under mostly CLR skies. Winds will generally follow a southerly component at KBLH with mostly clear skies this morning. T-storm activity is then expected to approach KBLH from the north-northeast during the late afternoon/evening hours, with lesser confidence that storms will actually reach the terminals. CIGS to become mainly FEW-SCT mid/high- level thru the rest of tonight and into Wednesday at KBLH && .FIRE WEATHER... Storm activity ramps up again today and Wednesday. Areas of strong winds and blowing dust will be the chief concerns today followed by better heavy rain potential Wednesday. A gradual decline in storm chances takes place from west to east beginning Thursday with near zero storm chances area-wide by Monday. MinRH values peak on Wednesday with values ranging from 30-40% lower elevations and 40-60% higher terrain. The lowest values will be on Monday with MinRH ranging from 20-25% lower elevations and 25-35% higher terrain. Apart from thunderstorms, winds will follow familiar diurnal patterns. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Benedict/AJ AVIATION...Kuhlman/Percha FIRE WEATHER...AJ
Area Forecast Discussion
National Weather Service San Diego CA
200 PM PDT Tue Aug 23 2022 .SYNOPSIS... Monsoonal moisture will continue to increase Wednesday into Thursday, leading to active days of thunderstorms over the mountains with a lesser risk over the deserts. Dry air will move in on Friday and fully into the region this weekend ahead of an upper trough, leading to dry conditions. Temperatures will be highest today with gradual cooling through the weekend before heating up next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... KEY POINTS: * Active monsoon thunderstorm days Wednesday and Thursday * Isolated thunderstorms possible Friday, then dry this weekend * Slight cooling through the weekend, then heating up next week Monsoonal moisture, the core of which is currently residing over SE California/SW Arizona with PW up to 1.8 inches per SPC mesoanalysis, will move northwest and overspread our service area through Wednesday. The monsoonal moisture will remain entrenched over our region on Thursday before shifting east on Friday. This progression will lead to active thunderstorm days for the mountains both Wednesday and Thursday with a lesser risk for the deserts. Areas west of the mountains look to remain dry. The flash flood concern exists Wednesday and Thursday afternoon, but confidence is not quite high enough for a Flood Watch at this time. Moisture levels are slightly lower than our previous active monsoon days. We will take a look this evening and overnight to see if a watch might be needed. The greatest flash flood risk will be over the mountains with a lower risk over the deserts. There is some indication on hi-res models, particularly our local WRF model, of a possible MCS moving towards the Coachella Valley and the San Diego County deserts while weakening late Wednesday night. Have added slight chance of tstorms for the lower deserts Wednesday night to account for this potential. Some HRRR runs even show light echoes making it west of the mountains with a few hundredths of an inch. This will be something to monitor for possible blowing dust over the lower deserts arriving late Wednesday night on thunderstorm outflows. The inland heat is peaking today, then we will see gradual cooling. First in part due to the monsoonal moisture and then due to better onshore flow as an upper trough digs off the U.S. West Coast by the weekend. This will spread cooling inland and humidity will lower a nudge as well. GFS and EC ensembles are pointing to a building ridge mid next week centered over SoCal. This scenario would bring building heat to the region as we close out August and move into September. Something to monitor. Differences are seen in the ensemble members next week in how much monsoonal moisture will return next week. The mean shows a slow, gradual increase while individual members vary from keeping moisture rather low to some members more aggressive on moisture return. For now, next week looks to feature building heat with a slight chance of thunderstorms returning as September arrives. && .AVIATION... 232015Z...Coast/Valleys...Low clouds with bases near 1000 FT MSL will continue across beach locations this afternoon. Low clouds will push back inland after 02z Wed and spread up to 20 SM inland, with bases 700-1000 FT MSL. Scatter out 17-19z Wed, though patchy BKN will continue into the afternoon across the immediate coast. Mountains/Deserts...Mostly clear skies through tonight. Iso TSRA will be possible in the mtns through 01z Wed with bases near 10,000 FT and tops to 30,000 FT MSL. Gusty and erratic winds, frequent lightning and heavy downpours will be possible vcty TSRA. && .MARINE... No hazardous marine weather is expected through Sunday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Excessive Heat Warning until 10 PM PDT this evening for Apple and Lucerne Valleys. PZ...None. && $$ PUBLIC...Gregoria AVIATION/MARINE...Moede