Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/12/21

Area Forecast Discussion
National Weather Service Dodge City KS
1103 PM CDT Wed Aug 11 2021 ...UPDATE TO AVIATION... .SYNOPSIS... Issued at 1044 PM CDT Wed Aug 11 2021 WV imagery indicates a broad scale upper level trough of low pressure stretched across the Northern Plains into the Upper Midwest and the Great Lakes. Near the surface, a stationary frontal boundary extends from west central Kansas into central Kansas. && .SHORT TERM...(This evening through Thursday) Issued at 259 PM CDT Wed Aug 11 2021 An area of very subtle 850 mb cold air advection was over northwest Kansas , behind a surface trough that was located from roughly west of Hays ans west of DDC, near GCK. Slighlty drier dew points in the upper 50s are noted to the west of this trough with much more rich surface dew points in the mid 60s pooling out ahead of the trough. The location of the trough may be off by a number of the CAMS which had been initiating convection father north and more in and east to west orientation through the day. The more recent HRRR runs seem to be an outlier, by developing the storms in the moisture gradient in the father southwest reaches of the forecast area with proliferation with time to the northeast. However the initiation pans out the risk period should be between and 4 and 10 pm with higher based storms and overall lower shear values. A downburst wind environment with potential for multiple cells creating cold pool surge anywhere along the initiation zone. Once the convective threat ends this evening, another mild night is expected with most model guidance showing low 70s for overnight lows over the higher moisture air southeast sections. A gradual shift to temperatures as cool as round 60 degrees is likely in the far west where the drier air will more efficiently radiate out. The cold front now extending from northeast Nebraska into extreme northeast Kansas is likely to be somewhere across the DDC forecast area on Thursday, and as such, probably the focus for another round of convection. With a sharper airmass discontinuity, the storms may develop a little earlier - the eastern 2/3rds of so the the area is under a Marginal risk for severe weather Thursday afternoon. The CAMS at t hits time as one might expect are all over the place on placement, however timing appears fairly reasonably assumed again in the mid afternoon onward, and perhaps lingering on in the southeast sections even longer ~beyond midnight. With increased shear/EHI parameters there should be risk for hail and wind both Thursday. .LONG TERM...(Thursday night through Wednesday) Issued at 259 PM CDT Wed Aug 11 2021 In the extended the skill in determining convection becomes more muddled, however it`s clear the temperatures will be nowhere near as hot as the last week or so. The national model blend comes in with fairly impressive precipitation probabilities on Friday again. The gfs/EC/canadian models generally show a sort of post frontal moist, still high CAPE and surface upslope environment that could easily support convective initiation or high MCS maintenance. This pattern may extend itself into the first part of the weekend as temperatures moderate significantly into the low 90s or even 80s with the loss of the hot downslope. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1101 PM CDT Wed Aug 11 2021 VFR conditions will prevail in the vicinity of all TAF sites through late Thursday afternoon. Southerly winds around 5 to 15kt will persist across much of southwest and south central Kansas overnight into mid/late Thursday morning as a weak frontal boundary remains quasi-stationary from west central Kansas into central Kansas. Light and variable winds are likely in vicinity of KHYS due to proximity to the boundary. && .PRELIMINARY POINT TEMPS/POPS... DDC 70 95 66 90 / 10 20 30 50 GCK 67 95 63 90 / 20 20 30 40 EHA 67 93 63 88 / 0 20 30 40 LBL 68 94 64 90 / 0 20 30 40 HYS 70 98 66 87 / 20 30 40 50 P28 74 98 70 91 / 10 20 30 50 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...JJohnson SHORT TERM...Russell LONG TERM...Russell AVIATION...JJohnson
Area Forecast Discussion
National Weather Service Grand Junction CO
524 PM MDT Wed Aug 11 2021 .SHORT TERM...(Tonight through Thursday night) Issued at 236 PM MDT Wed Aug 11 2021 CAM guidance has nailed the convection today as a few storms have just fired over the San Juans and a few are now popping near Wolf Creek Pass. Daytime heating, some minor midlevel instability, and a slight increase in moisture has allowed these storms to fire. Upper level winds are light so storms that are firing aren`t moving too much but with limited moisture, briefly heavy downpours are expected with some gusty outflow winds possible. Convection will die down towards sunset as daytime heating begins to wane. Smoke will remain across the area but HRRR guidance does show concentrations lowering some as the smoke plume from Cali shifts southward and afternoon gusts across the area provide decent mixing. Would still expect plenty of haze, however. CAM guidance also continues to highlight a shift of convection to include the San Juans but also areas north to include the central amounts and from about Vail Pass southward down to the San Juans. Confidence is high as the HRRR/NAMNest have initialized and performed well over the last few days. Forecast PWATs are also expected to climb over those areas so it follows that convection will do so as well. Steering level winds remain light under the high so the convection won`t be moving all that much but again, high based storms will allow some virga as gusty winds and brief, heavy showers reach the surface. .LONG TERM...(Friday through Wednesday) Issued at 236 PM MDT Wed Aug 11 2021 Strong mid-level ridging located over the Great Basin will continue to dominate the forecast through the weekend. Under this regime, the deepest and richest monsoonal moisture will be largely kept at bay and only encroach upon the far fringes of the forecast area, particularly in southwest Colorado. As a result, expect most shower and thunderstorm activity to be confined to the San Juans and perhaps along the Continental Divide where instability and moisture will be greatest. Elsewhere, hot and dry weather will be the rule with only minimal chances for rain. Daytime high temperatures will run 5 to 10 degrees above normal with the lower and desert valleys climbing into the upper 90s to near 100 each day. More significant changes begin to take place starting on Monday. Ensemble guidance continues to advertise a large, broad trough digging into the Pacific Northwest and forcing a suppression of the ridge stuck over the Great Basin farther south towards Mexico. This trough/ridge configuration will lead to a gradual influx of deeper monsoonal moisture into eastern Utah and western Colorado. In fact, the 12Z/11 EC ensemble guidance has PWATs progged to climb to ~150% of normal across most of the forecast area through midweek -- values that are certainly supportive of more robust and widespread shower and thunderstorm development. Thus, after a relatively dry and quiet stretch, confidence is increasing that another active monsoonal surge is on the way. As has been the case for most of the summer, flood prone areas and our most recent burn scars (especially Grizzly Creek, Pine Gulch, Pack Creek, etc) will be particularly at risk for heavy rain and potential flash flooding. Given increasing moisture and cloudiness, temperatures will be trending cooler during the first half of next week. As was previously mentioned, how long this upcoming monsoon episode lasts is still uncertain. Looking at the latest WPC 500mb height cluster guidance, there are two distinct camps depicting the evolution of the trough over the Pacific Northwest within the 3 major ensemble systems (EPS, GEFS and CMCE). One camp results in a more progressive (and thus a drier solution); the other results in unsettled weather persisting through the end of next week. At this point the odds for either solution are about 50/50, but there`s still plenty of time to sort out the details in the 7-10 day timeframe. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 518 PM MDT Wed Aug 11 2021 Convection along the southwest San Juans will diminish within the next hour with mainly clearing conditions and relaxed winds overnight. Inversions may trap smoke over lower valleys tonight with some MVFR conditions possible due to reduced visibility by sunrise. Otherwise, high pressure overhead will support decent diurnal mixing, and thus, breezy afternoon conditions for most TAF sites. A few isolated to scattered thunderstorms are expected to develop over higher terrain along the central and southern ranges Thursday afternoon possibly impacting DRO, TEX, GUC, and ASE. Gusty outflow winds will be the primary threat. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...TGR LONG TERM...MDM AVIATION...ERW
Area Forecast Discussion
National Weather Service Lincoln IL
902 PM CDT Wed Aug 11 2021 .SYNOPSIS... Issued at 203 PM CDT Wed Aug 11 2021 Wet and unsettled weather will remain possible through Friday ahead of a sagging cold front. Cooler and drier conditions will return this weekend in wake of frontal passage. Nevertheless, hot and humid conditions will return by the middle of next week, and will accompany thunderstorm chances. && .UPDATE... Issued at 902 PM CDT Wed Aug 11 2021 Updates have been made to increase PoPs mainly Knox, Stark, and Marshall Counties as thunderstorms have been developing along a boundary from northeast IL into southeast IA, well ahead of an earlier zone of convection earlier in the evening. Strong instability of 3000-3500 J/kg MLCAPE in this zone could produce strong storms, although higher potential for severe storms resides more in northern/northeast IL where shear is stronger and satellite imagery indicates more lift from a shortwave. Overnight, CAM models have been fairly consistent in depicting more widespread thunderstorm activity developing and sinking southward across central IL aided by a low level jet. Timing in intensity of the feature has varied widely. && .SHORT TERM...(This evening through Friday) ISSUED AT 203 PM CDT Wed Aug 11 2021 Deep convection has developed across central Wisconsin this afternoon along and ahead of a surface cold front. As this front drifts southeastward into northern Illinois this evening, some questions remain as to whether this activity will be sustained. The main limiting factor will be insufficient deep-layer shear as mid- level flow begins to weaken. Any renewed convective activity this evening will likely be triggered by a subtle mid-level shortwave impulse that rides above an intensifying LLJ. The magnitude and direction of the shear vectors will play a key role in determining convective mode this evening across central Illinois. The latest RAP analysis (19z) suggests bulk shear vectors will be oriented roughly parallel to the line of forcing, meaning that convection should grow upscale into a linear MCS. However, relatively weak 0-3km shear magnitudes (< 25 kts) means that the cold pool from this linear MCS would struggle to stay balanced, and would ultimately become outflow dominant. This all adds us to a raggedy line of storms north of I-72 later this evening. Still, bouyancy will likely be sufficient enough to yield an isolated severe wind threat, as a few downdrafts along the line punch down to the surface. A lot of forecast uncertainty remains for Thursday as convective debris likely keeps central Illinois capped through late morning. If clouds can break by afternoon, there will likely be enough bouyancy ahead of the cold front to support strong-to-severe thunderstorms. If clouds linger, the capping inversion will likely remain in place and suppress convective initiation as the front slowly sags southward across the outlook area. Despite mid 70s dewpoints pooling ahead of the front Thursday afternoon, clouds will likely hold temperatures down into the upper 80s. This should keep heat index values below advisory criteria on Thursday, but they will still be in the mid 90s. The cold front will begin to push south of I-70 by Friday. With similar CAPE/Shear profiles in place as Today and Thursday, the threat for isolated severe storms remains possible Friday ahead of the front. A temperature gradient will be present across the region on Friday afternoon, with low 80s behind the front, and upper 80s ahead of it. At this time, we do not anticipate a heat advisory for Friday either. .LONG TERM...(Saturday through Wednesday) ISSUED AT 203 PM CDT Wed Aug 11 2021 Cooler and drier weather conditions will work into the Midwest this weekend in wake of frontal passage. Surface high pressure will then continue to build across the region through early next week, suppressing the weather pattern. By Tuesday, winds will veer southerly as surface high pressure departs toward the Appalachians. This will allow temperatures and humidity to surge upward once again, and will mark the return of thunderstorm chances. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 659 PM CDT Wed Aug 11 2021 Potential thunderstorm activity overnight is the main focus for TAFs at this time. Significant uncertainty remains for development of a squall line that propagates southeastward into central IL late in the evening or overnight, so have included VCTS in TAFs starting 03Z-06Z, however amendments may be needed for the evolution of this feature. By morning, scattered SHRA/TSRA over the area should begin to dissipate, with precipitation likely to end by 15Z-18Z. Any thunderstorms could have MVFR cigs and IFR- MVFR vsby. Wind shear is anticipated from 05Z-12Z mainly KSPI- KBMI-KPIA area due to 40 kt SW wind at the 2000 foot level AGL. Otherwise, surface winds from the SW should predominate through the period, diminishing to 08-12 kts this evening, then increasing to 10-12 kts with higher gusts expected again by 18Z. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...37 SYNOPSIS...MJA SHORT TERM...MJA LONG TERM...MJA AVIATION...37
Area Forecast Discussion
National Weather Service Northern Indiana
820 PM EDT Wed Aug 11 2021 .SYNOPSIS... Issued at 820 PM EDT Wed Aug 11 2021 More storms are likely at times tonight through Friday before cooler and dry conditions prevail this weekend. High temperatures will be around 90 Thursday with heat indices around 100. && .SHORT TERM...(This Evening through Thursday night) Issued at 255 PM EDT Wed Aug 11 2021 Convective complex currently moving exiting eastern CWA and will to move east of the area shortly. HRRR seems to be best among the HREF members in handling this early afternoon convection so will lean that way for potential redevelopment tonight where ongoing convection in WI still expected to intensify this afternoon in the presence of highly sheared environment ahead of approaching mid- level short wave. Still anticipate organization into a more linear complex as it moves down into SE WI...NE IL...SW lwr MI...with plenty of uncertainty in severe threat for our area after being worked over this afternoon. In the wake of whats left of nocturnal complex tonight will once again see very warm...humid airmass in place and with decreasing clouds expect ample destabilization in the daytime hours leading to convective initiation to our west and tracking E/SE along baroclinic zone to potentially impact our area late Thursday/Thursday night. Hot and humid conditions expected again on Thursday with highs near 90 and dewpoints in the low to mid 70s will have heat indices approaching 100 in SE CWA so will consider having advisory in effect during the afternoon- early evening. && .LONG TERM...(Friday through Wednesday) Issued at 255 PM EDT Wed Aug 11 2021 Forecast period to begin with final push of frontal boundary through our area on Friday. Timing will dictate if any diurnal instability can develop in SE CWA before front moves through. Latest trends from deterministic models in line with SREF in early arrival for frontal passage that should preclude any threat for strong to severe storms. Canadian high pressure building in behind this front will bring much less humid conditions to the region as dewpoints drop into the 50s Saturday. Pleasant...dry weather continues into the beginning of next week with precip chances arriving toward the end of the period as remnants of TS Fred drift northward through the Appalacians. && .AVIATION...(For the 00Z TAFS through 00Z Thursday Evening) Issued at 815 PM EDT Wed Aug 11 2021 Next shortwave and associated weak frontal boundary will cross the area tonight with another round of storms. Timing is becoming a bit clearer but there is still some uncertainty based on inconsistencies among latest CAM`s. Also low confidence on coverage and severity of any thunderstorms...particularly at KFWA given late arrival and overall weak forcing. Will therefore continue with just a VCTS mention. Slightly higher confidence at KSBN and may introduce a TEMPO TSRA later. Some MVFR ceilings may be possible behind the rain Thu morning but confidence is too low to include with this package. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...Small Craft Advisory until 2 AM EDT Thursday for LMZ043-046. && $$ SYNOPSIS...AGD SHORT TERM...JAL LONG TERM...JAL AVIATION...AGD Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Marquette MI
752 PM EDT Wed Aug 11 2021 .SHORT TERM...(This evening through Thursday) Issued at 408 PM EDT WED AUG 11 2021 GOES imagery and RAP analysis show a cold front moving through Upper Michigan right now with ongoing convection south and east. While CAM solns are a bit scattered, add`l clearing and heating across the west and central should aid in some more development after 4. Latest RAP suggest MLCAPE values between 500 and 1000 J/kg, with 150 SRH and up to 50kts of 0 to 6km bulk shear. Latest HRRR does suggest some isolated development as well across the central with GOES-vis showing some agitated cu, but no reflectivity yet. Tonight, cold front will move through Upper Michigan bringing some relief to the humidity values. Upstream in MN, Tds have quickly fallen into the 40s, with GOES WV imagery showing broad subsidence as well. Pressure rises and CAA will bring some gusty winds, especially across the Keweenaw, where some values late tonight/tomorrow morning will approach 30mph. Tomorrow, it will be a breezy day behind the fropa tonight with gusts to around 25 mph across the central, closer to 30mph possible for the Keweenaw. Waves will increase through the day, leading to some beach hazards concerns east of Marquette by the evening. Temps may initially climb through the early aftn, but continued CAA will begin to cool things off by the evening. .LONG TERM...(Thursday night through Wednesday) Issued at 128 PM EDT WED AUG 11 2021 A persistent upper level low will continue to slowly meander over the Hudson Bay, and eventually move to th east over the north Atlantic this coming weekend. As this does so, upper level ridging will become appartent over the central CONUS, ecompassing the Great Lakes in the process with warmer temperatures. Temperatures will start off slightly below seasonal average on Friday before gradually warming to above season normals from the late weekend toward the middle of next week. Due to the persistent upper level ridge, we can expect mostly dry conditions for the medium to extended forecast period as well. The extended forecast will begin with a cold FROPA exiting the area by Thursday night across our eastern zones in the cwa, and CAA beginning to swing down from the north. This will bring much needed relief with regard to the persistent warm and humid conditions the Upper Michigan area has observed the last several days. By Friday, strong CAA aloft via nw flow will keep temperatures very comfortable. 850mb temperatures will bottom out near 5C over the Keweenaw, and warm gradually through the day to near 10C. Despite the cool temperature aloft, the surface high pressure and mostly sunny conditions will allow surface temperatures to warm into the 60s to lower 70s by late afternoon. This would make the daytime highs for Upper Michigan on Friday on par with what several areas have had as overnight lows for the past several days. This will make it a great start to the weekend as conditions look to remain tranquil and dry. Gradual warming because of a building upper level ridge over the central CONUS will spread to the east to include Upper Michigan, and the surface high pressure will continue to keep the area dry. Expect surface temperatures to increase daily through the middle of next week with daytime highs reaching the upper 70s to middle 80s, and little to no precipitation to occur. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 752 PM EDT WED AUG 11 2021 With drier air flowing into the Upper Great Lakes, VFR conditions will prevail at KIWD/KCMX/KSAW thru this fcst period. Westerly winds will generally be gusty at KCMX throughout, but particularly during the day on Thu when gusts up to 30kt are expected. Winds at KIWD/KSAW should gust to around 20kt during the day. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 408 PM EDT WED AUG 11 2021 A cold front passing over Lake Superior tonight will bring some CAA and pressure rises with gusty westerly winds. While there is some question as to the stability of the air mass over the lake, there is a chance for some gale force gusts to around 35 knots along the Keweenaw Peninsula in north-central Lake Superior late tonight, and then again tomorrow afternoon. The best chance for this will at the higher observation platforms. With the cooler airmass aloft, unstable conditions will help support winds near 20 knots across the lake through Friday afternoon. From there, high pressure building into the region is expected to keep winds calm and under 20 knots into next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement until 10 PM EDT this evening for MIZ014. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JAW LONG TERM...BW AVIATION...Rolfson MARINE...JAW
Area Forecast Discussion
National Weather Service Portland OR
342 PM PDT Wed Aug 11 2021 .SYNOPSIS...High pressure will continue across the region through Friday leading to hot and dry weather. An excessive heat warning is in effect from noon Wednesday to Saturday evening. The upper ridge will shift east this weekend with a slight cooling trend starting Saturday and continuing into early next week. && .SHORT TERM...TODAY THROUGH FRIDAY NIGHT...The weather remains quiet but hot under the influence of a 594 dam 500hPa ridge building into the area from the eastern Pacific. As of 2p.m. this afternoon, temperatures have already climbed well into the 90s. With surface heating continuing over the course of the next few hours, we would not be surprised if many Willamette Valley locations reach/surpass 100F today. In addition, the overnight recovery is expected to be less tonight, with temperatures in densely-populated, urbanized areas struggling to fall below 70 degrees (rural locations still only dipping into the middle to upper 60s) by daybreak. This positive feedback cycle continues tomorrow, with temperatures potentially warming more than today (given the higher overnight lows) provided smoke and haze advected into our area from fires to our north and east doesn`t trim them back a bit. Confidence is low in the exact magnitude and duration of the heat, but the models continue to depict a strong signal that temperatures will be significantly warmer (15+ degrees F) than normal. The ECMWF and GFS still agree that 850mb temperatures will warm to ~25C by tomorrow afternoon, and the NBM continues to suggest the probability of exceeding 100F tomorrow at PDX is around 70%. Friday looks very similar, though perhaps a degree or two cooler according to both MOS and NBM guidance. Still, the heat will be oppressive, especially for vulnerable populations such as the elderly, the very young, and those without air conditioning. In fact, heat stress is forecast to peak during the Thursday night into Friday timeframe since we`ll be multiple days into the event. Friday, the mention of thunder in eastern Lane and Linn counties stands to cover the potential for a few elevated cells that will form from orographic effects along the spine of the Cascades. This mention is only slight, since (1) instability doesn`t look overly impressive on this side of the crest, (2) the bottom of the unstable layer (known as the level of free convection, or LFC) is forecast to be right around the top of the Cascades, and (3) the mid to upper-level steering flow has a westerly component that will drive convection quickly east of the crest (the edge of our area of responsibility). Still, we believe the mention is warranted given the weak 1.5PV tropopause fold forecast by the NAM, along with the NBM and SREF`s 15-25% forecast chance for thunder in the area. Some concern even exists in elevated, nocturnal convection tomorrow (Thursday) night in the Lane County Cascades and foothills, but most high resolution models - with exception to the more-aggressive HRRR - suggest that anything moving NW into Lane County overnight will be fizzling, and hence only capable of dropping a few sprinkles through the dry boundary layer. -Bumgardner && .LONG TERM...Saturday through Tuesday night...After a few days of very hot weather, Saturday will initiate a pattern shift that will bring some relief to the area. On Saturday, vertically stacked onshore flow will become dominant, which will bring in cooler air from the North Pacific. The change to onshore flow stems from the shift of the upper level high to the east, and a weak low forming aloft over the Pacific. This low is accompanied by elevated southwesterly winds in the jet stream aloft around 35,000 ft. Because of the onshore flow, relief from smoke may occur as it may be pushed out of the area from nearby fires. This of course depends on whether or not there are new starts that may occur in the previous days. By Sunday, a broad low that currently sits over the northern Gulf of Alaska will widen and begin its slow advance southward along the B.C. coast. As the low aloft moves southeast, a shortwave within the flow will move over the area beginning Sunday morning. This shortwave will bring more cool air to the area and even a slight chance for some rain showers along the northern portions of the forecast area. Models have varied quite a bit in regards to the timing and location of the precipitation so confidence is low. There is a chance that if the parent low stays further north, that the rain could miss our area completely. In contrast, if the low dips further south, potentially more of the area could experience rain. Have decided to keep PoPs and accumulation low to represent the uncertainty. Long term models show a pretty consistent pattern in regards to the overall synoptic pattern with the main differences lying in the intensity of the system. The GFS is currently the stronger and more southerly pattern, while the ECMWF and Canadian keep a bit more conservative strength and trends to the north over interior Canada. Even with these differences, a similar overall outcome is expected...cooler temperatures, stronger onshore flow, and a slight chance for rain in the north on Sunday and Monday. -Muessle && .FIRE WEATHER...Strong high pressure over the northeastern Pacific will gradually drift eastward through Saturday. A subsidence inversion will lower to 2500-3000 feet Thursday and Friday bringing poor humidity recovery for the Cascades and Coast Range ridges. Additionally, cut-off low pressure moves north Thursday and Friday bringing significant instability and strong ventilation potential. Friday also brings an elevated thunderstorm threat for the Central Cascades. && .AVIATION...High pressure over the region will result in predominantly VFR conditions areawide through 00z Friday. The main exception to this will be along the coast where a southerly wind reversal and accompanying fog and low clouds will spread northward up the coast. This will likely result in a mix of IFR and LIFR conditions pushing into KONP between 06-12z Thursday. There is a chance it could push all the way northward and impact KAST between 12-18z Thursday, but nearly all model guidance suggests it will fall short and this does not seem unreasonable given the strength of the current high pressure ridge overhead. Smoke from the wildfires burning in the Oregon Cascades will continue to primarily impact eastern Lane, Linn and Marion Counties over the next 24 hours. The latest HRRR smoke model does suggest some smoke from BC/WA wildfires will drop southwestward through the Columbia River Basin and begin to impact the Columbia River Gorge and northern Willamette Valley between 18z Thursday and 00z Friday. Do not expect this to bring IFR visibilities at this point based on limited smoke upstream, but we might see surface visibilities drop into the 5-9 mile range in a worst case scenario. Confidence is not terribly high that these visibilities will come to fruition, though given smoke coverage is still somewhat limited across eastern Washington and southern British Columbia. For detailed regional Pac NW aviation weather information, go online to: KPDX AND APPROACHES...High pressure aloft will result in light winds and VFR conditions through 00z Friday. Some smoke from BC/WA wildfires will begin to spread westward through the Columbia River Gorge between 18z Thursday and 00z Friday and may result in surface visibilities falling into the 5-9 mile range. Do not expect this to bring IFR visibilities at this point based on limited smoke upstream, but we might see surface visibilities drop into the 5-9 mile range in a worst case scenario. Confidence is not terribly high that these visibilities will come to fruition, though given smoke coverage is still somewhat limited across eastern Washington and southern British Columbia. /Neuman && .MARINE...High pressure over the northeast Pacific and thermally induced lower pressure shifting inland today will result in breezy northerly winds decreasing over the next 24 hours. There could be a few isolated spots with gusts to 21 kt during the remainder of this afternoon and early evening, but not expecting wind gusts this strong to be widespread enough to necessitate a Small Craft Advisory. A southerly wind reversal will move northward up the coast overnight and bring areas of fog and a brief burst of 10 to 20 kt southerly wind gusts, primarily to the waters within 10 to 20 NM of the Oregon coast. It remains unclear if these gustier southerly winds will make it all the way to the south Washington coast overnight. Light southerly winds should then more or less develop across all of the waters Thursday into Friday and persist through the weekend. These southerly winds are expected to remain well below Small Craft Advisory wind gust thresholds of 21-33 kt. Expect seas to climb into the 8 to 10 ft range over the next 24 hours as an incoming northwesterly swell pushes into the waters. Seas should then gradually decrease thereafter and drop below 5 ft for the weekend. Seas may increase slightly early next week after a weak front drops southeastward across the waters late Sunday into early Monday. /Neuman && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Excessive Heat Warning until 10 PM PDT Saturday for Cascade Foothills in Lane County-Cascades in Lane County-Central Coast Range of Western Oregon-Central Columbia River Gorge- Central Willamette Valley-Coast Range of Northwest Oregon- Greater Portland Metro Area-Lower Columbia-Northern Oregon Cascade Foothills-Northern Oregon Cascades-South Willamette Valley-Upper Hood River Valley-Western Columbia River Gorge. Red Flag Warning from 11 AM to 10 PM PDT Friday for Mt. Hood National Forest West of Cascade Crest. Red Flag Warning from 11 AM Thursday to 10 PM PDT Friday for Central Oregon Cascade Foothills-East Slopes of the Central Oregon Coast Range-Willamette National Forest. WA...Excessive Heat Warning until 10 PM PDT Saturday for Central Columbia River Gorge-Greater Vancouver Area-I-5 Corridor in Cowlitz County-South Washington Cascade Foothills-South Washington Cascades-Western Columbia River Gorge. Red Flag Warning from 11 AM to 10 PM PDT Friday for Eastern Gifford Pinchot National Forest Mt Adams Ranger District- Extreme South Washington Cascades and Foothills. PZ...Small Craft Advisory from 6 AM to 10 AM PDT Thursday for Columbia River Bar. && $$
Area Forecast Discussion
National Weather Service Pueblo CO
308 PM MDT Wed Aug 11 2021 .SHORT TERM...(This evening through Thursday) Issued at 239 PM MDT Wed Aug 11 2021 Currently...Isolated thunderstorms have formed over the eastern San Juans and srn Sangres, as mid level moisture has begun to increase in these areas this afternoon. Various CAMs suggest additional convection may develop eastward along the NM border in Las Animas County by 22z, spreading eastward into Baca County 22z-02z, as low level convergence strengthens near the old frontal boundary stretching from nern NM into sern CO. Tonight... Most convection should end fairly quickly this evening, as better moisture and mid level forcing remain to our south through the night. Should see clouds decrease enough overnight for seasonably cool min temps, though drier air over the nrn half of the area may allow high mountain valleys in the central mountains to drop into the 30s by early Thu morning. Thursday...Weak upper wave drifts eastward across CO, while new surface cold front drops south through the plains, becoming nearly stationary near the Arkansas River by late afternoon. Old cold front/surface trough will also still lie somewhere near the srn CO border as well. In general, felt the 18z HRRR solution was fairly reasonable, suggesting convection will fire on the plains near/just behind the cold front by mid-afternoon, with additional activity along the surface trough over the far se by late day. Still some spread in model solutions though, as NAM is generally along/north of the Palmer Dvd with the main convective area, while the GFS is farther south in NM. Deepest moisture/instability forecast to be over the far sern plains, where CAPE in the 1-2k j/kg range could lead to some stronger storms, despite the absence of much in the way of 0-6km shear. Farther west over the mountains, mainly isolated activity, though areas near the Continental Divide will see slightly better storm coverage. Max temps north of the front will cool slightly versus Wed numbers, while the remainder of the area sees very little change. .LONG TERM...(Thursday night through Wednesday) Issued at 239 PM MDT Wed Aug 11 2021 Friday... As an upper-level trough moves off far to the northeast, an upper- level high pressure system will begin to build in from our southwest. This will cause some disturbance to the flow aloft, allowing vorticity maxima to propagate over our area and assist in the development of showers and thunderstorms. Scattered to likely thunderstorms will form over the mountains in the afternoon, mainly over parts of the Continental Divide, with scattered storms expected over the rest of the area throughout the rest of the day. Models are resolving 700-900 J/kg of CAPE over most of the mountains, and over 1300, on average, over the Palmer Divide and further east. Surface flow is also expected to have a consistent upslope component over most of the eastern plains, which will further assist in providing lift. The vast majority of storms will stay over the higher terrain, but as the upper-system tracks east conditions could allow for a few storms to form and/or propagate over the eastern plains later in the day. Shear is not expected to be very strong, so the current severe threat is on the low side, with the main concern being for flash flooding conditions, especially over burn scars. Saturday-Wednesday... Starting into the weekend, as the closed upper high sits near the Great Basin, and mid-level low pressure center will form to our southwest as well, funneling in much more moisture to the area. This gives us a more typical monsoon moisture set up, and precipitation coverage is expected to increase on Saturday and Sunday. Moisture will continue to funnel in through the beginning of next week as the low begins to shift the upper-high to the west, which could create more widespread showers and thunderstorms. Overall, the forcing is mainly centered over the mountains. With a distinct lack of forcing over the eastern plains, they should remain largely free of storms. However, should things play out as the long-term guidance suggest, the first half of next week could be busy with heightened flash flooding concerns. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 239 PM MDT Wed Aug 11 2021 VFR conditions expected at all taf sites the next 24 hrs, as smoke layer across the region continues to gradually thin. Isolated afternoon/early evening convection across the srn mts and along the NM border will slowly diminish this evening, and any impacts at taf sites should be limited to briefly gusty outflow winds at KALS and KPUB. On Thursday, cold front drops south through the plains, bringing enhanced chances for thunderstorms at both KCOS and KPUB after 20z. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...PETERSEN LONG TERM...GARBEROGLIO AVIATION...PETERSEN
Area Forecast Discussion
National Weather Service Reno NV
305 PM PDT Wed Aug 11 2021 .SYNOPSIS... Above-average temperatures will peak this week as high pressure builds into western Nevada through Saturday. Moisture and instability will continue to expand across the Sierra and western Nevada this week as well. These ingredients will usher in the return of thunderstorms across the region through the end of the week into the weekend. Variable smoke and haze will persist as wildfires continue across the West. && .SHORT TERM... A broad area of high pressure aloft extends from a close high offshore the Pacific Northwest southwest into the Four-Corners region and northern Mexico. During the course of this week, a closed upper high will strengthen over the Great Basin as a nearly stationary upper low lingers over the Eastern Pacific west of the CA coast. The resulting interaction of these two systems will allow monsoonal moisture to permeate further northwest and north across the Sierra and into western Nevada through the shorter-term period. As the upper high builds and spreads west into CA through tomorrow, area temperatures will continue to heat up to around 5-8 degrees above seasonal normals through this week. The rising temps will allow the return of sufficient instability to increase the risk of thunderstorms each day mostly over the Sierra and far western NV. Outside the gusty outflows from these developing storms, winds will remain generally light over the region. A short-lived zephyr wind will still make its summertime appearance late each day before pushing east off the Sierra into far western NV basin areas. * THUNDERSTORMS: Coverage is going to favor the Sierra crest this evening (south of Lake Tahoe) and the Sierra/Lassen County convergence into northwest NV tomorrow as an upper wave moves northwest along the CA coast through Thursday evening. Mid- level storm flow will be east-southeast and tend to push storms to the west side of the crest with weak forcing aloft to enhance a few more energetic storm cells. However, low- level outflows could instigate a few storms close to the Hwy 395 corridor in Mono County into the far western NV. As the upper wave moves further into northwest CA, sufficient moisture and CAPE will be present to spread the risk of isolated storms into northeast CA/northwest NV tomorrow into Friday morning. By Friday into Saturday, warmer air infiltrating the mid-levels, with no dynamic forcing to trigger storm development other than the interaction with the complex terrain, will keep storm coverage mostly isolated across the region. PWATs will range between 0.75"-0.85" Friday and Saturday with some hybrid storms becoming more capable of producing locally heavy rains with possible debris flow impacts to area burn scars. Gusty outflow winds to 40 mph remain a real possibility with high storm bases and enhanced DCAPE values reaching mostly above 1000j/kg. * HEAT AND SMOKE: Temperatures will be pushing 100 degrees for warmer lower valleys and close to 90 in the Sierra valleys. ECMWF Shift of Tails guidance revealed that Minimum Temps overnight tomorrow could reach the 0.8 to 0.9 percentile for most areas over the northern Sierra and Washoe County. While the above-average temperatures are not a new thing for this time of the year, ongoing smoke and depressed air quality can exacerbate the potential for heat health symptoms over those areas affected by higher temperatures and denser smoke. There will be a potential for additional smoke transport into areas east of the Sierra as late-day zephyr breezes develop to the lee of the northern Sierra ridges. -Amanda .LONG TERM... (Saturday and beyond) Ensemble simulations continue to show a weakened area of high pressure withdrawing eastward after Sunday. An upper short wave that will advance into and lift northeast across the Pacific Northwest and northern Rockies early next week should increase a dry-stable southwest upper flow over CA/NV. The same long-range model/ensemble guidance still points to an upper short wave of some form entering the forecast picture early next week. Some uncertainty surrounds the general depth and timing of the incoming upper wave as ensemble cluster predictions show differing scenarios. European ensemble guidance favors a more split flow aloft while increasing shares of the GFS ensemble members lean towards a more symmetric structure of forcing and momentum needed to boost gusty afternoon winds that could reach more critical levels. The increasing and drier southwest upper wind flow will bring a decrease in thunderstorm coverage going into next week. The change in the large-scale winds and the daily storm outflow potential will only bring an increased uncertainty to any predictions of smoke and haze coverage and AQI impacts in the coming days. -Amanda && .AVIATION... Periods of smoke and haze at the surface and aloft will impact terminals in the Sierra and western NV for the next couple days (and likely well beyond) as the Dixie wildfire remains active. Terminals across western Nevada and eastern CA could range between VFR and MVFR through Thursday as smoke transport/mixing varies; the possible exception is south and west of KSVE closer to the Dixie Fire where periods of IFR conditions are on the table. HRRR smoke simulations keep most of the smoke out of the Tahoe Basin and eastern Sierra again through Thursday although slantwise visibility will likely be degraded. Low afternoon-evening thunderstorm potential (10-20% chance) will spread from the Sierra south of Hwy 50 near/west of the crest today to northeast CA and far western/northwestern NV Thursday through Saturday. Thunderstorms are most likely to be rather garden variety with localized moderate-heavy rain, pea-size hail, and wind gusts up to 30-40 kts. -Snyder && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Seattle WA
853 PM PDT Wed Aug 11 2021 .SYNOPSIS...An upper level ridge will continue to build and strengthen over Western Washington through the rest of this week, resulting in very hot temperatures. Offshore flow develops but eases by Friday, with cooler marine air returning to the coast. A weak weather system is still expected to move into the region over the weekend, with cooler conditions and possibly some light rain chances for the start of next week. && .SHORT TERM /TONIGHT THROUGH SATURDAY/...Forecast remains on track this evening. Previous short term discussion follows. The heatwave is off to strong start with temperatures as of 2PM in the low 90s for areas in the Interior. With overnight lows in the mid 60s not much relief is expected to occur. High temperatures Thursday and Friday are expected to be even higher with highs in the mid to upper 90s likely for the Interior. There could be some slightly stronger onshore flow by Friday that will keep the coastal areas significantly cooler. With the hot temperatures and little recovery during the overnight an Excessive Heat Warning remains in effect through Friday for much of the area. While Saturday will still be hot we are expecting better night time recoveries due to increased onshore flow. While sky conditions will remain mostly cloud free, hazy skies are likely, especially along and near the Cascades. This haze will be mostly due to smoke moving into the area from fires to our north and east. This smoke is expected to stay mostly aloft. While models such as the HRRR smoke are showing noticeable concentrations at the surface, it is believed that these concentrations are over forecasted due to the model over mixing the entire atmosphere. That said, areas of Whatcom County and Lewis Counties could see smoke concentrations that would bring the AQ down to Sensitive for Unhealthy Groups, there is high uncertainty with that. And we will be consulting with our AQ partners if trends appear to change. Butwin .LONG TERM /SUNDAY THROUGH WEDNESDAY/...A return to cooler and moister weather is expected through much of the long term forecast period. With the upper level ridge being forced out of the area by a weak weather system and then by a series of little shortwaves moving through the area. While there is a chance of some rain Sunday into Monday it is expected to be very light, with areas receiving only a few hundredths of an inch. Areas at the higher elevations of the Cascades and Olympics could see up to a couple tenths but this will do little to lessen the fire weather dangers. Butwin && .AVIATION....Northwesterly upper level flow overnight, with weakening onshore flow becoming offshore late tonight. Low level winds through much of the interior will remain northerly at 10 kt this evening, easing to around 6 kt by 08z. The atmosphere remains dry with generally clear skies, though some elevated smoke/haze may pass overhead at times. VFR conditions will generally prevail, though some brief IFR marine stratus may redevelop into KHQM for a few hours toward daybreak Thursday morning. KSEA...Clear skies and VFR conditions will persist through Thursday. Northerly winds continue, with any gusts tapering and winds easing after 08z. Expect another round of northerly winds increasing to around 10 kt with Thursday afternoon and evening. && .MARINE...Persistent northerly winds at small craft advisory levels and building swell over the outer coastal waters through early Thursday morning, with the small craft advisory remaining in effect for the outer waters through 11 AM. The weak onshore flow will transition to easterly flow late tonight and persist through much of the day Thursday. Models have been consistently showing weak onshore flow through the Strait of Juan de Fuca redeveloping late Thursday evening. This will become more established Friday, with southerly flow returning to the coastal waters. Seas this weekend remain 4 to 5 ft, dominated by a west swell. && .FIRE WEATHER...Red Flag Warning remains in effect for Thursday and Friday for the Cascade zones (658 and 659) due to dry and very unstable conditions. Expect light offshore flow to develop tonight and take hold into Thursday across most of the region and daytime humidities to dip close to critical values during the afternoon. Modest recoveries are expected Thursday night for many locations, but a strengthening subsidence inversion that is expected to lower to around 2500 or 3000 ft will likely yield very poor recoveries for elevations above this. Elsewhere, while hot and dry conditions are expected, it is not anticipated that conditions will be severe enough to warrant a westward expansion of the warning at this time. Cooler and more humid air arrives late in the weekend. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...Excessive Heat Warning until 7 PM PDT Saturday for Bellevue and Vicinity-Cascades of Pierce and Lewis Counties-Cascades of Snohomish and King Counties-Cascades of Whatcom and Skagit Counties-East Puget Sound Lowlands-Seattle and Vicinity- Southwest Interior-Tacoma Area. Red Flag Warning from 11 AM Thursday to 10 PM PDT Friday for West Slopes of the Central Cascades Generally above 1500 Feet-West Slopes of the North Cascades Generally above 1500 Feet. Heat Advisory until 8 PM PDT Friday for Olympics. Excessive Heat Warning until 8 PM PDT Friday for Bremerton and Vicinity-Everett and Vicinity-Hood Canal Area-Lower Chehalis Valley Area-Western Skagit County-Western Whatcom County. Heat Advisory until 8 PM PDT Thursday for North Coast. PZ...Small Craft Advisory until 11 AM PDT Thursday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm- Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm. && $$
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
523 PM MDT Wed Aug 11 2021 .DISCUSSION...(This Evening Through Wednesday) Issued at 206 PM MDT Wed Aug 11 2021 Upper air analysis shows an upper low over Manitoba, with the upper ridge over the west coast, and northwest flow aloft over our region. A weak frontal boundary is expected to move through the forecast area late tonight. This will lead to slightly cooler temperatures Thursday and a higher relative humidities. Expect highs to reach into the upper 70s and low 80s for Thurs/Fri, before rebounding back to the 90s through the weekend. The added post frontal moisture and slight increase in instability Thursday night may be enough to generate an isolated storm or two over the blackhills region, though overall chances are low, and mostly dry conditions are expected through Monday. Fires in SE Montana continue to generate areas of smoke over the forecast area. HRRR near surface smoke model shows an increase in reduced visibility this evening as winds transition from westerly to out of the north. Over the weekend, the upper ridge slides eastward over the rockies and eventually the plains region, helping to bring back the warmer temperatures. We also may see near critical fire conditions Sun/Mon as RH`s drop into the upper teens, with breezy conditions possible. Chances for precipitation increase by Tuesday, as the ridge moves east of the forecast area and southwest flow aloft develops. && .AVIATION...(For the 00Z TAFS Through 00Z Thursday Evening) Issued At 522 PM MDT Wed Aug 11 2021 VFR conditions are expected through the TAF forecast period, although areas of MVFR visibility due to smoke may occur this evening, especially over northeastern Wyoming and around the Black Hills area. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...None. WY...None. && $$ DISCUSSION...Dye AVIATION...Bunkers
Area Forecast Discussion
National Weather Service Las Vegas NV
755 PM PDT Wed Aug 11 2021 .SYNOPSIS...Northwest Arizona will see scattered afternoon and evening thunderstorms through Thursday. Elsewhere, storms will be more isolated over the mountains of southern Nevada and southeast California. Thunderstorm activity should be minimal Friday through the weekend followed by increasing monsoonal moisture leading to an upswing in storms early next week. && .UPDATE...With the setting sun, the limited amount of convection which did manage to form today is quickly dying, with the only remaining area of concern across northern Mohave County. A small cluster of storms which formed near the Mt Trumbull loop continues to develop southward towards Peach Springs, but is showing signs of gradual waning as well. Convective inhibition was too great across most of the lower desert terrain today to initiate any notable storm activity, which isn`t too surprising given the scale of the MCS that developed in northern Arizona last evening. This complex tracked all the way to the Pacific coast, leaving a broad pool of rain cooled air in it`s wake. The atmosphere may begin to recover slightly tomorrow, though the general synoptic flow and magnitude of instability will be quite similar, with storm chances favored mainly in Mohave County. Will be making some adjustments mainly to the PoP forecast this evening to better align with current trends. -Outler- .AVIATION...For McCarran...Expect typical south- southwest winds around 8KT this evening. Quiet weather is expected with occasional clouds around 15kft through the TAF period. Thunderstorms are possible Thursday afternoon, but mainly east of Las Vegas in the Peach Springs corridor. For the rest of southern Nevada, northwest Arizona and southeast California...Conditions will be VFR with typical light diurnal winds. A few thunderstorms may develop, mainly in northwest Arizona, Thursday afternoon with gusty surface winds and convective turbulence possible. && .SHORT TERM...through Friday night. The main area to watch this evening will again be central and southern Mohave County and the lower Colorado River Valley. Though the pattern setup is similar to Monday evening, the potential for organized thunderstorms does not look quite as high. The stalled mid level circulation over southern Arizona will continue to be a factor in aiding convection this afternoon, but considerable cloud cover extending across much of central and southern Mohave County was limiting surface heating and leading to a later start. Recent runs of the HRRR indicate thunderstorms developing just east of the Mohave county border in Coconino and Yavapai counties will work their way down over Peach Springs toward Kingman and Wikieup late this afternoon and evening, but may not be able to stay together west of the Hualapai mountains. Elsewhere over southern Nevada and southeast California, isolated pulse thunderstorms will be possible over the mountains this afternoon but should dissipate fairly quickly in a limited moisture environment as they slowly drift to the west or northwest off the mountains. Gusty winds will be possible near any of these storms. Only very subtle changes in the overall pattern are expected Thursday with moisture lingering over the same areas. Mohave County will again see the best potential for scattered afternoon thunderstorms with a continued tendency to propagate toward the southwest. Light flow aloft and lingering moisture will remain over the area Friday and it appears the circulation over southern Arizona will have moved southward and the limited thunderstorm potential should be driven by surface heating with isolated storms over the mountains. .LONG TERM...Saturday through Wednesday. While Saturday and Sunday once looked favorable for an upswing in thunderstorm activity, the latest NBM and model ensembles now indicate Monday though Wednesday should be the period with increasing chances for thunderstorms. This is due to a strong area of high pressure over the northwest states that is forecast to migrate southward and set up over central Nevada which will shunt the easterly wave over southern Arizona a little more southward. The high is then forecast to migrate toward the Four Corners which will turn the flow more southerly across our region by Monday and the easterly wave stalls around Yuma then slowly lifts northward and brings an influx of moisture into our region which begins to interact with a weak broad trough digging from the Pacific northwest into northern Californian and Nevada. This pattern would support the higher chances for thunderstorms indicated by the latest NBM PoP grids though confidence is fairly low on how the various synoptic features will come together. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM/LONG TERM...Adair AVIATION...Outler/Nickerson For more forecast information...see us on our webpage: or follow us on Facebook and Twitter