Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/18/20


Area Forecast Discussion
National Weather Service Grand Junction CO
554 PM MDT Mon Aug 17 2020 .SHORT TERM...(Tonight through Tuesday night) Issued at 234 PM MDT Mon Aug 17 2020 High pressure remains in control over the western CONUS today. This high pressure system is centered over western Utah, placing eastern Utah and western Colorado in light northerly flow in the mid and upper-levels. A meager amount of moisture has circled around this high pressure system, and has encroached on the Sawatch and Sand Juan mountains this afternoon. RAP mesoanalysis indicate SBCAPE values in the 500-1000 range, and sure enough a few showers and thunderstorms have been able to capitalize on this instability today. Short-term forecast soundings indicate an extremely dry subcloud layer however, so precipitation amounts will still remain quite light from any storms that do fire today. At most, a tenth of an inch or so of rain (and some small hail) will be about all we can muster in the San Juans this afternoon and evening. Smoke will continue to be one of the primary weather stories. General northerly flow will transport smoke plumes southward from active fires today. Overnight, expect downvalley drainage winds to generally carry smoke westward along the Colorado river basin drainage. Areas in eastern Utah may begin to see lower visibility as this drainage flow carries smoke from the Pine Gulch Fire westward toward the Grand Flat, Moab, and Canyonlands. Tuesday will turn out quite similar to Monday. High pressure is not expected to move much, if at all, and isolated showers and thunderstorms will once again be possible in the San Juan range. Northerly flow will continue to carry smoke southward, then westward in low-level drainage overnight. The one change on Tuesday may be a slight increase in high temperatures by a degree or two, due to a slight upward bump in mid-level temperatures. Overall forecast confidence remains high throughout the short-term and minimal adjustments were done in this forecast package. .LONG TERM...(Wednesday through Monday) Issued at 234 PM MDT Mon Aug 17 2020 The high pressure over the Great Basin will move slightly south over Arizona on Thursday before and then remain there through the long term forecast. Long story short, that means not a whole lot of change should be expected from day-to-day. However, one change will be the increasing moisture through the period. The high pressure is expected to slowly drag in moisture from the southwest CONUS...and wrap in clockwise around the high. Looking at time- series data, some long-term solutions suggest that GJT will reach nearly 50F dewpoints next week. That`s a bit hard to believe given that we rarely see sfc dewpoints that high in the best monsoonal conditions. But, if this moisture does end up making it`s way 270 degrees around the high like models are suggesting, we will likely see precipitation chances move down in elevation through the next 7 days. At any rate, the high terrain will continue to see increased showers and storms thanks to the recycled moisture. How much rainfall vs wind reaching the ground remains the question across the board. Confidence remains low in a particular solution (in other words placement of the high) beyond this weekend...so opted to follow blended guidance which generally keeps the status quo. Temperatures will remain consistently warm...around 10 degrees above normal for much of the area through the long-term periods. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 549 PM MDT Mon Aug 17 2020 There is an actual thunderstorm with real precipitation that could impact KDRO through 02Z with gusty winds and possibly some moderate rainfall. Otherwise smoke in the Eagle and Colorado River Valleys could bring MVFR conditions at times over the next 24 hours. Away from showers or storms winds will be light. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...MAC LONG TERM...SS AVIATION...TGJT
Area Forecast Discussion
National Weather Service Green Bay WI
1024 PM CDT Mon Aug 17 2020 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Tuesday Issued at 233 PM CDT Mon Aug 17 2020 The latest RAP analysis and satellite/radar imagery show a large trough positioned over the central Great Lakes. The left front quad of the 115 kt jet streak has shifted east of the region. But thermal troughing over northern WI has led to more convective clouds with the heat of the day. A few spotty showers have popped over northeast WI along the Bay breeze where surface based instability is 200-300 j/kg, but they fizzled relatively quickly. Will keep an isolated shower mention along the lakeshore through the end of the afternoon. Looking upstream, high pressure is positioned across the Plains where skies are mainly clear. Forecast concerns include the shower activity and the possibility of ground fog late tonight. Tonight...Once any showers diminish late this afternoon or early this evening, will see clearing skies across the region. Some cirrus may move overhead at times, but otherwise should have a good radiational cooling night. Like the past two nights, low temps should fall a couple degrees below their cross-over temps across the northwoods. Therefore think more ground fog is likely to develop late tonight, and will keep a patchy fog mention in the forecast. Lows ranging from the middle 40s up north to the middle 50s over the Fox Valley. Tuesday...High pressure will be centered over the region. More convective clouds will build with the heat of the day, but they shouldn`t be as beefy as today, and no showers are expected. Slightly cooler highs in the low to mid 70s. .LONG TERM...Tuesday Night Through Monday Issued at 233 PM CDT Mon Aug 17 2020 Like the previous forecaster detailed, northwest flow will continue through the end of the week. Then the upper flow attempts to turn more zonal this weekend, bringing better chances for a round or two of showers/storms. The severe weather threat still looks low through the end of the week. But as warmer and more muggy air slides closer to the region, the threat of severe weather will gradually increase through the weekend. Tuesday night into Thursday...Surface high pressure will initially be present across the region on Tuesday night. Warmer and more humid air will be pushing across western Ontario and Lake Superior through the night, which may be enough to touch off a few showers or isolated storms over far northern WI late in the night into Wednesday morning. Will keep a slight chance in the forecast. Most models show precip chances continuing in the Lake Superior region on Wednesday night into Thursday, where waves of warm advection will be occurring. Most if not all of the area will remain dry during this time, but temperatures will gradually be trending warmer (low to mid 80s on Thursday). Rest of the extended...Models insist on shortwave energy approaching the region during the Friday night into Saturday time period, which appears to be the next chance of widespread showers and storms. Though it`s a little far out to get a handle on the details, winds aloft appear relatively weak, so a severe threat will likely depend on the timing of the system and how it coincides with peak heating. Another chance of precip could also arrive early next week. Temps this weekend will like be above normal. && .AVIATION...for 06Z TAF Issuance Issued at 1022 PM CDT Mon Aug 17 2020 Generally good flying conditions are expected for the next 24-36 hours as a weak anticyclone gradually shifts into the region. The one possible exception is the potential for patchy fog across the north late tonight. Surface dew point depressions across north- central Wisconsin have decreased to the point where patchy fog will probably begin showing up in the next few hours. Spreads across central Wisconsin were greater, so there is less potential for fog there. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......MPC AVIATION.......JS
Area Forecast Discussion
National Weather Service Lincoln IL
602 PM CDT Mon Aug 17 2020 .SYNOPSIS... Issued at 246 PM CDT Mon Aug 17 2020 Isolated to scattered showers and thunderstorms will still be possible late this afternoon through this evening as a cold front passes through the area. Once this moves southeast, dry conditions are expected through the rest of the week. Temperatures will become cooler behind the front as high pressure builds into the area. Overnight lows should be in the middle 50s to middle 60s, with temperatures rebounding into the lower 80s tomorrow. && .UPDATE... Issued at 602 PM CDT Mon Aug 17 2020 Forecast was updated to increase PoP`s across the area tonight. Latest radar mosaics showing a broken line of showers from the southeast tip of Iowa to north of Peoria to Indianapolis, while a line of showers also extends south to Jacksonville. HRRR and the NAM Nest show this settling southward through the evening, with a gradual weakening as we get to near midnight. The NAM and RAP show some rejuvenation south of I-70 toward sunrise, but will monitor this a bit longer and keep PoP`s in that area in the 20-30% range late tonight. && .SHORT TERM...(This evening through Tuesday) ISSUED AT 246 PM CDT Mon Aug 17 2020 A cold front is will move through the CWA late this afternoon through this evening. Though instability will be limited due to very warm mid level temps, isolated showers and storms are still possible. Will keep isolated to scattered precip ongoing in the forecast for this evening. Unfortunately this isolated to scattered precip will linger in the southeast parts of the CWA tomorrow morning and then slowly diminish to the southeast during the afternoon. Otherwise, most of the CWA should be dry and mostly sunny with cooler temps. && .LONG TERM...(Tuesday night through Monday) ISSUED AT 246 PM CDT Mon Aug 17 2020 With the cold front past the CWA Tuesday night, dry weather will return to the area as high pressure builds into the region. Though one or two of the models may indicate some scattered precip in the area around the weekend, dry weather is expected through the rest of the week and through the following weekend. Temps will start as a tad cooler than normal, but warm back to around or just above normal by the end of the week and through the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 602 PM CDT Mon Aug 17 2020 Cold front roughly extends from KMQB-KPNT at 22Z and will settle southward through the evening, shifting winds to the northwest to north. Numerous showers are lined up near the boundary, but thunder has been rather sparse so far, and will only mention VCSH at this point. Shower activity should be south of the TAF sites by about 06Z. Ceilings will drop as the showers arrive and should largely stay VFR, though pockets of ceilings below 3,000 feet are possible. Skies clear overnight and VFR conditions prevail the rest of the forecast period. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Geelhart SYNOPSIS...Auten SHORT TERM...Auten LONG TERM...Auten AVIATION...Geelhart
Area Forecast Discussion
National Weather Service North Platte NE
655 PM CDT Mon Aug 17 2020 .SHORT TERM...(This evening through Tuesday night) Issued at 321 PM CDT Mon Aug 17 2020 A warm front across ern Wyoming will be the focus for isolated severe thunderstorm development across the Panhandle late this afternoon and this evening. The forcing is very uncertain as satellite does not indicate any disturbances moving through WY this afternoon. Afternoon heating alone might not be enough of a trigger but the CAMs suggest an isolated storm or two will form, perhaps along the Pine Ridge in northwest Nebraska. Winds aloft will be strong and MLCAPE around 1500-2000J/KG produces Bulk Richardson numbers less than 50. The RAP model shows the warm front moving east tonight into ncntl Nebraska which could continue to be the focus for isolated showers and thunderstorms. There is little or no elevated CAPE in the NAM or RAP models so this may turn out to be just showers or sprinkles. Wind aloft remain strong Tuesday afternoon and the shear actually increases as the low level inflow winds below 750 mb increase a bit. The CAMs suggest another isolated severe storm potential. The short term model blend suggested isolated thunderstorm chances late Tuesday afternoon and evening across western Nebraska. The temperature forecast uses the warmest guidance, the GFS MAV, for highs in the upper 80s to upper 90s Tuesday and the cooler MET guidance for lows in the 50s to lower 60s tonight and Tuesday night. This is appropriate for the very dry conditions developing across western Nebraska where the warmest temperatures will occur. .LONG TERM...(Wednesday through Monday) Issued at 321 PM CDT Mon Aug 17 2020 The best rain chance develops Thursday with a h700mb disturbance moving through ncntl Nebraska. This is supported by the NAM, GFS and it`s ensemble mean for scattered thunderstorm chances. The ECM is silent on this system. Winds aloft will be strong, near 40 kts at h500mb, and this could support a severe weather threat but it is too early to make a call as suggested the by the day4-8 SPC discussion. Otherwise, limited forcing and low moisture appear to be limiting rain chances to isolated. A period of very hot dry weather should develop Friday through Monday with the possibility of a back door cold front Sunday or Monday. All of the 850-700mb temperature data are pointing to an amplification of daytime heating Thursday and beyond. The only thing holding back the temperature forecast is bias correction which drops highs several degrees off the deterministic model blend. The official forecast for highs in the upper 80s to lower 90s is very conservative given the caliber of the subtropical ridge across the wrn U.S. and the temperature records which have fallen over the weekend in that area. Although the ridge will not migrate into the Plains, temperatures at h850mb across wrn and ncntl Nebraska will gradually rise several degrees supporting a warming trend which is not shown in the temperature forecast. Later forecasts will likely mark temperatures up at least a few degrees on some days. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 655 PM CDT Mon Aug 17 2020 VFR conditions are expected the next 24 hours at the KLBF and KVTN terminals. Elevated showers and thunderstorms are expected to develop after 06Z near or just east of the KLBF and KVTN terminals. Have not included in the latest TAFS, and will consider including in the next scheduled issuance if confidence increases. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Roberg
Area Forecast Discussion
National Weather Service Pueblo CO
319 PM MDT Mon Aug 17 2020 .SHORT TERM...(This evening through Tuesday) Issued at 319 PM MDT Mon Aug 17 2020 Lackluster convection occuring across the mountains this afternoon where dew points are in the 20s and 30s. This is a little higher than the day before for some areas, but beneath the upper high moisture is not sufficient enough to net more than a few hundred J/kg of CAPE. Inverted V sounding suggest most storms will produce gusty winds, and lightning, with only spotty light to moderate rainfall amounts. Have bumped down pops considering current coverage and while high res models suggest the possibility of some weak to moderate intensity thunderstorms through 03z-04z, risk for flash flooding on burn scars this evening should be much lower than past several days. Convection should wind down after sundown with low temperatures similar to last nights. High res hrrr smoke runs suggest hazy skies will return for most of the western 2/3rds of the forecast area after some small improvement this afternoon. Upper high retrogrades westward for Tuesday with sufficient moisture within the upper high for mainly isolated convection. Best chances will be across the southwest mountains. Inverted V soundings suggest gusty winds, lightning and some spotty light to moderate rainfall amounts will be possible, but most areas should stay fairly dry. Across the plains, dew points drop off considerably in the afternoon with a surface trough axis/diffuse dry line taking shape across the far southeast plains. 12z runs seem to keep axis of higher dew points in Kansas during the afternoon and will keep a dry forecast through the afternoon. Have maintained some silent pops out that way but think any activity will hold off until later in the evening. As for smoke and haze...after some morning hazy skies for the I-25 corridor and points westward, hrrr suggests some marginal improvement during the afternoon for the I-25 corridor and as flow aloft becomes more northerly to even northeasterly. -KT .LONG TERM...(Tuesday night through Monday) Issued at 319 PM MDT Mon Aug 17 2020 Tuesday Night and Wednesday: Isolated to scattered PoPs have been included over the mountains through around midnight on Wednesday. There is an band of instability located over the far eastern plains (Kiowa, Bent, Prowers, and Baca Counties) that storms are expected to form along. CAPE values have trended downward over the past few model runs, so at this point, storms are expected to form but should be sub-severe, with an emphasis on a gusty winds risk (LCLs around 12kft) during that time period. Wednesday afternoon has been trending towards a more substantial rain event over the eastern mountains on Wednesday afternoon. There is a shortwave propagating over the region during the mid afternoon and surface to 700hPa easterly winds forcing air up the eastern mountains. The NAM, GFS, and ECMWF all have strong easterly winds being resolved, but the ECMWF has a much drier outcome. Meteorologically, the NAM and GFS`s outcome make more sense. Those showers and thunderstorm are expected to spread east over the I-25 corridor during the evening on Wedensday. The expected convection over the mountains means that there is a better chance for burn scar flash flooding. The severe thunderstorm risk is low at this time, since CAPE values will be less than 1000 J/kg over the adjacent plains, but the northwesterly flow aloft (enhanced wind shear) could spark a rogue strong to severe thunderstorm during the afternoon. The easterly flow at the surface and the convection and cloud cover developing will keep temperatures near average for this time of year over the plains, with values in the mid 90s, but the mountains and mountain valleys will continue to be hot as the upper ridge remains to the west. Values over the mountain valleys will be in the upper 80s to low 90s and the mountains will be in the 60s to 70s. Thursday: Dry conditions are expected throughout the morning and the early afternoon, but a distinct shortwave and trough axis are expected to propagate over the region during the late afternoon to early evening. While impacts vary with different models outputs, the consensus is that convection will begin around 3 to 5 PM over the mountains, which is later than what the region has been seeing lately, and will spread over the eastern plains by 6PM lasting through the overnight. CAPE values are generally below 1000 J/kg, so severe storms aren`t likely. The coverage is the most uncertain part of the forecast. The GFS is aggressive with QPF values, which is normal, the ECMWF has a dry outcome, which doesn`t make much sense meteorologically, the NAM has the initial development over the eastern mountains but that is when it reaches 84 hours, and the Canadian has development primarily over the southern I-25 corridor and plains. Friday through Monday: A tropical system is expected to be near the Baja California Peninsula on Friday, which could enhance PWAT values over southern Colorado. The result will be scattered to likely chances of precipitation over the central mountains, but will bring daily isolated to scattered chances of showers and thunderstorms over the rest of the mountains and the lower elevations. The sensible weather will also be more humid compared to what southern Colorado is used to, especially over the mountains and mountain valleys. The added moisture should promote more widespread cloud cover, therefore temperatures are expected be around average for this time of year. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 319 PM MDT Mon Aug 17 2020 VFR conditions expected at the TAF sites over the next 24 hours. Breezy southeast winds with gusts up to 25 kts at KCOS and KPUB should abate during the evening with winds becoming light and diurnally driven overnight. KALS could see outflow from thunderstorms over the mountains which could cause erratic winds but given very isolated coverage to thunderstorms have kept mention of VCTS out of the TAF for now. Any thunderstorms over the mountains should diminish after sundown. A similar pattern is expected for Tuesday though winds across the plains will be light and northerly through the morning before gradually shifting around from the southeast around 10 kts in the afternoon. -KT && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...KT LONG TERM...SKELLY AVIATION...KT
Area Forecast Discussion
National Weather Service Reno NV
233 PM PDT Mon Aug 17 2020 .SYNOPSIS... Isolated to scattered showers and thunderstorms through Tuesday will decrease to isolated coverage south of Highway 50 Wednesday. Dry conditions are expected Thursday into the weekend. Afternoon temperatures remain hot in the lower valleys although morning lows should fall mid to late week for some relief from the daytime heat. Smoke and haze continue in areas with wildfires in the region. && .SHORT TERM... Forecast highlights: - Isolated to scattered fast-moving thunderstorms with brief heavy rain and possible strong outflow winds through Tuesday...much diminished chances Wednesday north of Hwy 50. - Increasing winds Wednesday/Thursday...heightened fire concerns. - Remaining very warm (Sierra valleys) to hot (lower valleys) but cooling mornings mid-late week for some relief from daytime heat. - Areas of smoke and haze from wildfires, mainly for extreme eastern CA and western/northwestern NV. A couple upper waves entrained in the remnant moisture plume from former tropical system Fausto have brought (and continue to bring) another round of nocturnal and morning thunderstorms with prodigious lightning and gusty winds in northern California, with one cluster rolling through Plumas, Lassen, and Modoc counties a bit earlier. North to northwest winds in the wake of the storms brings concern for smoke spread from the Loyalton Fire into portions of extreme eastern CA (including the Lake Tahoe area) and far western Nevada this afternoon and evening. As a side note, from the office we have seen some rapidly developing pyrocumulus (once again!) over the Loyalton Fire...so that is clearly still quite active and capable of producing copious smoke. Currently, cumulus have developed over the Sierra south of Highway 50 and moved quickly off to the northeast into far western NV. They do not look to be explosively developing, perhaps due to skinny CAPE profiles and too much wind shear at the present time. However, a few have developed into weak thunderstorms and, as the afternoon progresses, instability should increase some over western and west-central Nevada for more intense convection. Also, there may be a boundary setting up along the leading edge of the aforementioned NW-N winds in northwestern NV and extreme northeast CA which could be a focus for a few thunderstorms later. As far as the nature of isolated to scattered storms today, some of the HRRR runs indicate some stout outflow winds between 40-60 mph from its modeled convection. This makes plenty of sense with hot temperatures and temp/dewpoint spread of 50-60 degrees expected in western and west-central NV. Otherwise, storms are likely to bring a brief shot of heavy rainfall along with the concern for dry strikes and new fires. Similar storm features are likely on Tuesday. Late tonight and Tuesday morning, there is yet again a chance for late night and morning thunderstorms across northeast California as another wave moves northward in the remnant moisture from former tropical system Fausto. Low temperatures once again look mild with cloud cover and moisture. This continues the limited cooling of late with urbanized areas/areas with sparse greenery of the most concern (lows 65-75); the heat advisory continues through Tuesday evening for western/west-central NV. Wednesday, drier and more stable southwest flow aloft finally moves into the region as low pressure approaches the Pacific Northwest. However, a few mid-afternoon to early evening storms are still possible well south of Highway 50 as residual moisture and better convergence allow for convective development for one more day. Winds will increase Wednesday for increased fire danger...see the fire discussion for more details. Wednesday night, cooler temperatures than we have seen lately are expected as drier air and much less cloud cover combine to allow for better radiational cooling. -Snyder .LONG TERM...Thursday through next Monday... Thunderstorms are not expected Thursday through at least Sunday morning as the drier air and possible warming mid-levels as the upper ridge expands westward combine to cap off deep convection. Storms could return Sunday and Monday afternoons as continued very warm temperatures eventually allow for convection to build up sufficient instability. Temperature-wise, above to well above average high temperatures are likely to continue through the extended. However, overnight lows should continue to be cooler than recent days so some relief remains on the table for the overnight/morning hours. -Snyder && .AVIATION... Isolated to scattered thunderstorms are yet again expected for this afternoon and evening across much of the region...with the best chances over western and west-central Nevada. Storms today will be capably of producing gusts 35-45kts, small hail, and brief heavy rainfall. The strongest storms could produce gusts to 50 kts along with reduced surface visibility due to blowing dust, most likely out in the Basin and Range of west-central NV this evening. Smoke and haze from the Loyalton Fire may limit visibility (terrain obscuration), both surface and slant-wise, in extreme eastern CA north of Lake Tahoe and into portions of western and northwest Nevada. This could continue for a least the next couple days if the fire remains active (which it is as of this writing), especially as afternoon westerly flow increases Tuesday and, more significantly, Wednesday. -Snyder/Hoon && .FIRE WEATHER... Thunderstorms are firing off once again today with the main focus of the activity in far western portions of fire zone 271 and in the Eastern Sierra into the western Nevada Sierra Front. These storms will continue to progress toward the northeast tonight, with showers possibly lingering into the west central Nevada Basin. There are low end chances (~15-20%) for thunder overnight into the early morning hours Tuesday in northeast California. Additional thunderstorms are possible Tuesday afternoon and evening following the same pattern as today. Main thunderstorm threats remain gusty and erratic outflows in addition to locally heavy rain. There is plenty of moisture available for the storms to put down rain; however, they are moving fast and we have already seen rather efficient lightning starts the past several days. New fire starts are certainly possible outside of the storm cores. Moving onto Wednesday, we start to see a drier air mass work into the region, esp for areas north of US-50 as a trough moves into the Pacific Northwest. This trough will also bring an increase in wind speeds, with the strongest winds also north of US-50. Wind gusts could reach around 35 mph with humidity values dropping to 10-15%; therefore, we have issued a Fire Weather Watch for fire zones 278/270/458/423/420. Portions of zone 429 may also see critical conditions, but it looks to be limited to areas north and west of Fallon, so have left it out of the watch for now. South of US-50 additional thunderstorms will be once again possible on Wednesday afternoon and early evening. The driest conditions are likely for Thursday with poor recoveries for midslopes and ridges Wednesday and Thursday nights. Chances are looking good for moisture and thunderstorms returning by later in the weekend. -Dawn && .REV Watches/Warnings/Advisories... NV...Heat Advisory until 11 PM PDT Tuesday NVZ001-003>005. CA...Heat Advisory until 11 PM PDT Tuesday CAZ070. Dense Smoke Advisory until 5 PM PDT this afternoon CAZ071. && $$ For more information from the National Weather Service visit... http://weather.gov/reno