Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/15/21

Area Forecast Discussion
National Weather Service Boise ID
836 PM MDT Sat Aug 14 2021 .DISCUSSION...Lots of smoke and a few clouds (mostly cirrus) cover the forecast area this evening. Visibilities around the region were in the 3 to 5 mile range at most observations sites. Little change is expected over the next 24 hours. Winds were out of the west to northwest at 5 to 15 mph. We will continue the excessive heat warning, even though the smoke has kept temps down a couple of degrees below our previous expectations. It still looks like the smoke will be largely pushed out of the area by a system moving in Monday and Monday night. No changes at this time. && .AVIATION...Mostly MVFR with visibility restrictions due to wildfire smoke at the surface and aloft through Sunday. Surface winds: west to northwest 5-10 kts except 10-15 kts south and east of KBOI before 03z. Winds aloft at 10k feet MSL: northwest 10-20 kts. Hot afternoon temperatures will increase density altitude. && .PREV DISCUSSION... SHORT TERM...Tonight through Monday night...Latest indications are that heat and smoke will continue into Monday, especially on the Idaho side, but a cold front should end it in eastern Oregon Monday. HRRR smoke model shows significant improvement in the smoke immediately after the frontal passage, and although the HRRR model goes out only through Sunday night the trend strongly suggests that near-surface smoke will decrease greatly on the Idaho side late Monday or Monday evening, and smoke aloft will decrease a few hours later. Tuesday looks breezy and cooler as the upper trough comes in. West-southwesterly flow aloft should also continue to improve air quality. A slight chance of showers and thunderstorms is forecast in the Idaho mountains Monday afternoon and evening with the cold front. LONG TERM...Tuesday through Saturday...An upper trough will continue to dig across the Intermountain West through mid-week, ushering in cooler temperatures and breezy winds. This system will also generate a chance of thunderstorms over higher terrain of southwestern Idaho on Tuesday and Wednesday. Conditions will be the coolest on Wednesday at roughly 10-15 degrees below normal. As flow aloft slowly turns northwesterly and then westerly, temperatures will gradually rebound to near normal by Saturday under mostly dry conditions. && .BOI WATCHES/WARNINGS/ADVISORIES... ID...Excessive Heat Warning until midnight MDT Sunday night IDZ012-033. OR...Excessive Heat Warning until midnight MDT /11 PM PDT/ Sunday night ORZ061>064. && $$ DISCUSSION...SP AVIATION.....JT PREV SHORT TERM...LC PREV LONG TERM....AL
Area Forecast Discussion
National Weather Service Denver/Boulder CO
741 PM MDT Sat Aug 14 2021 .UPDATE... Issued at 740 PM MDT Sat Aug 14 2021 Storm activity is increase versus the normal decrease around this time of day. We have one wave of storms moving through the mountains with a flash flood threat for the burn areas, while a more significant wave of storms dropping south across southeast Wyoming and the Nebraska panhandle. Some of these storms are severe with very large hail of golf ball to a couple reports near baseball sized and then one 3" diameter hail report east of Scottsbluff, NE. The highest MLCAPE is over the northeast corner of the state with close to 2000-2500 J/kg, and then amounts decrease rather quickly to the south and west to just a few hundred J/kg closer to Akron and Fort Morgan. The severe thunderstorm watch looks good over the northeast corner with very large hail possible from storms through about midnight, but also a threat of severe farther west into Morgan and northern Weld County. Even where MLCAPE was limited to <1000 j/kg, the bulk shear was sufficient for severe storms near Cheyenne, WY. Overall forecast has this on track, with only minor adjustments for timing/PoPs. && .SHORT TERM...(This evening through Sunday) Issued at 233 PM MDT Sat Aug 14 2021 Showers and storms have developed in the mountains and near the Palmer Divide. By the late afternoon and evening, there will be more instability which will allow for better coverage of storms and for some to move off the mountains and foothills to the adjacent plains. Model data hasn`t provided much help today. In fact, the 18Z HRRR and 18Z NAM Nest have the exact opposite solutions with how the storms will play out. The HRRR thinks showers and storms will be confined to the mountains, foothills, and near the Denver metro while the NAM Nest has strong storms over the northeastern plains. A solution somewhere in-between will likely end up verifying. Some weak convection will come off the higher terrain with gusty winds and there will be a threat for stronger storms over the northeast corner although the coverage may not be as high as the NAM Nest has. The environment across the northeast corner is ripe for severe storms if storms were to develop there. Right now, the SPC mesoanalysis page shows a mixed layer CAPE of up to 3,000 j/kg and bulk shear of around 50 knots near Ogallala yielding a supercell composite of 16. So if storms that are currently moving south of the Black Hills make it to the northeast corner of Colorado, they could produce severe hail and damaging wind gusts. Storms will eventually dissipate around midnight as instability decreases. Low temperatures will be a few degrees above normal. Models are picking up on a shortwave trough moving into northern Colorado tomorrow morning providing enough lift to generate isolated showers and storms. PoPs were added to the forecast to get a mention of precipitation in the forecast during the morning hours Sunday. The morning cloudiness/showers will keep high temperatures down tomorrow so the high temperatures were lowered around 3 degrees meaning Denver should see the upper 80s instead of the low 90s. The left over moisture will mean precipitable water values will reach the highest values they have in a while. With some weak instability developing by the afternoon, scattered showers and storms will redevelop. There`s not much of a severe threat due to the limited instability and shear. The slow moving nature of the storms and good moisture in place will mean there will be at least a limited threat for flash flooding in the burn areas. .LONG TERM...(Sunday night through Saturday) Issued at 233 PM MDT Sat Aug 14 2021 Scattered showers and thunderstorms will linger into Sunday evening and then dissipate by midnight as the airmass stabilizes. For Monday and Tuesday, the strong upper level high over the Great Basin will weaken and slide southeast across the Central and Southern Rockies. This will usher in warmer and drier air. Should be enough moisture and instability for isolated thunderstorms Monday. Drying continues into Tuesday with precipitable water values falling to a half inch or less over the higher terrain. Very little convection is expected for Tuesday. The showers and storms that form should be limited to the higher terrain. Southwest flow aloft will increase Wednesday ahead of an upper level trough moving across the Pacific Northwest and Northern Rockies. Moisture is expected to increase ahead of this trough with scattered thunderstorms. The timing and how deep this trough digs is still uncertain, but there should be an increase in thunderstorms Wednesday, especially over the mountains. A cold front should have moved through the area by Thursday, so expect cooler temperatures. There could be another round of scattered thunderstorms as well. It will depend where the best lift ends up. Will keep a chance for showers and thunderstorms in the forecast for Friday and Saturday as northwest flow aloft prevails behind the upper level trough off to the northeast. Expect cooler temperatures during this period with highs in the lower to mid 80s over northeast Colorado. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 740 PM MDT Sat Aug 14 2021 We will have a few showers/weaker thunderstorms in the area through about 05-06Z, and still looks like VCTS is an adequate way to represent this chance. The most likely impact from these showers and storms would be gusty winds that could reach 35 knots if a storm were to get close enough. A shortwave trough that moves across the area tomorrow morning could produce light rain showers and a mid level cloud deck, but VFR conditions will prevail. During the afternoon Sunday, there will be a chance (Prob30) of storms again mostly after 21Z. && .HYDROLOGY... Issued at 740 PM MDT Sat Aug 14 2021 There will be slow moving storms with decent precipitable water values so there will be at least a limited threat for flash flooding over the burn areas. That threat should mostly end by 10 pm or so this evening. On Sunday, the morning convection will make the forecast difficult because it may limit afternoon instability. Isolated showers and thunderstorms are expected over the higher terrain Monday and Tuesday. Moisture and thunderstorm activity will be limited so the flash flood threat for the burn areas will be low. Moisture and thunderstorms are expected to increase Wednesday and Thursday. If this occurs, there will be an increase in the flash flood threat. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Barjenbruch SHORT TERM...Danielson LONG TERM...Meier AVIATION...Barjenbruch HYDROLOGY...Barjenbruch/Danielson/Meier
Area Forecast Discussion
National Weather Service Burlington VT
1017 PM EDT Sat Aug 14 2021 .SYNOPSIS... High pressure drifting over the North Country will bring us drier and slightly cooler weather that will last through Tuesday morning. The weather will then turn more unsettled from Tuesday afternoon onward once the high pressure moves to our east and return southwesterly flow develops. Temperatures and mugginess will increase each day through the end of the week, along with the return of afternoon showers and thunderstorms. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 1017 PM EDT Saturday...No changes needed with this update. Some isolated stratus over the high terrain is visible on satellite otherwise skies are clear across the North Country. Latest RAP MSLP analysis shows gradient beginning to slacken therefore expect winds to continue to diminish over the next couple hours. Still thinking some pockets of patchy valley fog are possible. Overall, a pleasant mid August night is on tap. Previous Discussion...A very quiet period of weather is starting this afternoon behind this morning`s frontal passage. In the wake of the front, expansive surface high pressure will build in, allowing for subsidence to develop. Main forecast challenge is potential for fog development overnight. Plenty of moisture at the surface from this morning`s rainfall despite the drier air mass moving overhead, and with clear skies tonight, thinking we will see some patchy fog develop. Limiting factor will be light sustained northwesterly flow just off the surface, which will keep enough mixing in place to limit coverage of fog to sheltered valleys. Overnight lows tonight will be in the upper 40s to mid 50s...substantially cooler than the lows the previous few nights. Conditions will also be noticeably less muggy than our recent weather. For Sunday, looking continued quiet and dry with persisting subsidence under high pressure. Will just see some shallow fair- weather cumulus clouds develop in the afternoon and highs in the low to mid 70s. Lows Sunday night will again be in the upper 40s to mid 50s. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 344 PM EDT Saturday...Expect sunny weather with no precipitation for another day due to dry air at all levels of the troposphere as sprawling high pressure remains over the area. Towards daybreak, the leading edge of a warm front will approach the southern portions of North Country, so they should see a layer of low clouds roll overhead. Elsewhere, only thin, high clouds may make an appearance late. Temperatures will be near normal for mid August with highs ranging from 75 to 80 and lows in the 50s in most locations. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 344 PM EDT Saturday...Isolated to scattered showers and a rumble of thunder will be mainly over the Adirondacks westward into the St. Lawrence Valley on Tuesday. Farther east, upper- level support for precipitation will be weaker and in the absence of deep moisture, expect mainly dry conditions over Vermont through the day with partly to mostly cloudy skies. Decreasing heights will likely push eastward to work in concert with high precipitable water (above the 90th percentile for the date) to cause more numerous showers with moderate to heavy rainfall to move through the whole North Country at times from Tuesday night through Wednesday. Again cannot rule out thunder during the daytime hours, but looks like limited instability will be available given little cooling aloft and relatively poor surface heating. Highs will be a few degrees above normal where there is ample sunshine on Tuesday, with otherwise near normal temperatures continuing through Thursday with some continued unsettled and humid weather. As of now, it looks like the hottest period of this upcoming warm and humid stretch will be Friday to Saturday. On these days, heat index values could again surpass 90 in most areas and surface based instability will likely support thunderstorms. With rising upper level heights expected, the threat for severe weather is low. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Through 00Z Monday...Mainly VFR through the TAF period with clear skies and generally light winds expected. Expected generally clear skies with only some low stratus remaining over the high terrain. Areas of patchy fog/low stratus are possible at KSLK, KMPV & KEFK after 08z. Anticipate periods of MVFR visibilities with VLIFR ceilings possible. Any reductions to visibilities/ceilings should lift by 12z with VFR through the remainder of the period. Winds will between 5-10 kt from the W/NW becoming light and variable overnight. Tomorrow, winds will remain generally 10 kt or less. Outlook... Sunday Night: VFR. NO SIG WX. Monday: VFR. NO SIG WX. Monday Night: VFR. NO SIG WX. Tuesday: VFR. Slight chance SHRA. Tuesday Night: Mainly VFR, with local MVFR possible. Slight chance SHRA. Wednesday: Mainly MVFR, with local VFR possible. Chance SHRA. Wednesday Night: Mainly VFR, with areas MVFR possible. Chance SHRA. Thursday: Mainly MVFR, with areas VFR possible. Chance SHRA, Slight chance TSRA. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Duell NEAR TERM...Duell/LaRocca SHORT TERM...Kutikoff LONG TERM...Kutikoff AVIATION...LaRocca
Area Forecast Discussion...CORRECTED
National Weather Service Billings MT
241 PM MDT Sat Aug 14 2021 .DISCUSSION... Tonight through Sunday night... Satellite imagery shows a broad ridge over the western CONUS and WNW flow over our region. There is a weak shortwave in southeast ID that is developing a cumulus field over the Beartooth/Absarokas and there are a couple weak radar echoes popping up over the mountains near Gardiner. Any chance of light showers or weak t-storms will be confined to our southern mountains late this afternoon and evening. It will otherwise be a clear and dry night. There is also a good deal of smoke spreading eastward over our cwa, to near Rosebud county as of mid afternoon. 18Z HRRR certainly supports what we have been expecting: a shift to much smokier skies for the next couple days from the numerous western North American wildfires. Sunday will be a bit hotter than today with the only fly in the ointment being smoke impacts on solar radiation. In addition to temps near 100 degrees, we will see somewhat breezy and well- mixed W-NW winds tomorrow afternoon as surface trof shifts to eastern MT. If the smoke cover is thick enough it could shave a few degrees off of temps and a few mph off of wind gusts...but based on temps we are achieving today it may not matter much. Have upgraded our Fire Weather Watch to a Red Flag Warning, which will cover the entire Sunday-Monday period. We will see a poor humidity recovery Sunday night, then another hot day but with a chance of late day t-storms (and erratic convective outflow winds) across the region Monday. See extended discussion for details. Otherwise, potential for diurnal t-storms on Sunday will again be confined to our southern mountains. JKL Monday through Saturday... We will start off the week with temperatures nearing the triple digits... but finally, on the horizon, is the possibility for widespread rain and below normal temperatures! High pressure and downslope winds will start of the work week, cranking temperatures back near the 100s and keeping conditions very dry. Some decent mix-down will occur with westerly winds for the foothills west of Billings, bringing about gusts 25-30 mph. The red flag warning from Sunday will roll over through Monday as well to account for these elevated fire weather conditions. The more pleasing story revolves around a prominent upper low swinging southeast from the Pacific Northwest and through our area. Widespread rain is expected, though amounts vary greatly, depending on the placement of the low. Some lightning activity is possible, but this will be more of a strictly rain event. The cold front will swing through Tuesday night (so Tuesday, being a pre- frontal day, will still see temperatures in the upper 90s), bringing in extremely cooler temperatures that will only allow for highs to reach the 60s for much of south-central Montana, and 70s for southeastern Montana. Northwest flow with weak, embedded shortwaves behind it will keep below-normal temperatures in place for the rest of the weak, albeit just not as cold as Wednesday`s temperatures. Oh, and don`t be surprised if those in the higher mountains see a couple snowflakes from Wednesday`s system ;) Vertz && .AVIATION... VFR conditions prevailing through this evening for most of the area. Wildfire smoke will begin to impact locations west of BIL this evening. MVFR conditions are likely after midnight for these locations, and after sunrise Sunday for BIL. Expect reduced slant range visibility throughout the period. Behringer && .PRELIMINARY POINT TEMP/POPS... Sun Mon Tue Wed Thu Fri Sat ----------------------------------------------------------- BIL 065/098 067/098 065/092 054/065 051/073 054/076 053/077 00/K 01/U 23/T 68/T 53/T 34/T 43/W LVM 057/097 059/094 057/089 049/066 046/073 047/076 046/078 00/K 02/T 25/T 88/T 53/T 34/T 43/T HDN 060/100 060/100 062/094 053/070 049/074 051/076 050/078 00/K 01/U 22/T 57/T 63/T 34/T 33/W MLS 062/100 064/100 067/095 058/074 051/073 053/075 053/077 00/H 00/U 21/B 45/T 53/T 33/T 33/W 4BQ 062/099 063/098 066/096 058/076 053/071 053/075 053/077 00/K 00/U 11/B 35/T 64/T 33/T 33/W BHK 060/099 062/099 065/097 058/079 051/072 050/075 050/077 00/H 00/U 11/B 34/T 54/T 23/T 33/W SHR 058/097 059/096 060/092 053/070 047/071 047/074 047/076 01/K 01/U 22/T 47/T 75/T 44/T 43/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...Red Flag Warning in effect from 9 AM Sunday to 9 PM MDT Monday FOR ZONE 117. Red Flag Warning in effect from noon Sunday to midnight MDT Monday night FOR ZONES 123>132. WY...None. && $$
Area Forecast Discussion
National Weather Service Cheyenne WY
333 PM MDT Sat Aug 14 2021 .UPDATE... Issued at 332 PM MDT Sat Aug 14 2021 Severe Thunderstorm Watch 440 issued for the Nebraska Panhandle today through 11 PM this evening. && .SHORT TERM...(This evening through Sunday) Issued at 150 PM MDT Sat Aug 14 2021 Latest surface obs and satellite scanning convergence boundary stretching across portions of southeastern WY and the NE Panhandle with early convection across the the SD Black Hills and light echo now over the Laramie Range. CAM guidance remains split in thinking with the HRRR once again being the quiet outlier this afternoon with limited convection across the Panhandle while the NAMNEST has stayed consistent with more widespread thunderstorms from now through late tonight. SPC continues a sliver of slight risk for far eastern NE Panhandle with marginal including only eastern tier of counties from Dawes south to Cheyenne. Latest PRECIP sounding from CSU shows robust CAPE profile of over 1000 J/kg but lackluster 0-1 km shear of about 7 kts. CIN is the kicker again today as inversions in the sounding and values into the 150 to 200 J/kg range. So similar to yesterday, topography will be key to help spur initiation. LLJ again could play a bit of a spoiler tonight across the Panhandle with any remaining convection and energy remaining. Highs today on the warmer side from Friday into the upper 80s and low 90s for many. Sunday will see an uptick in low and midlevel moisture coupled with passing upper level shortwave that again will spur convection perhaps more widespread including into SE WY. Highs near-similar to today`s forecast. .LONG TERM...(Monday through Friday) Issued at 220 AM MDT Sat Aug 14 2021 Monday...With some decrease in low and mid level moisture, we should see a decrease in late day shower and thunderstorm coverage. Slightly cooler temperatures for most locations, notably across the Nebraska Panhandle. Tuesday...Even warmer temperatures as the flow aloft becomes southwest with 700 mb temperatures near 18 Celsius. Looks like enough low and mid level moisture for isolated to scattered late day thunderstorms. Wednesday...Shower and thunderstorm coverage becomes scattered to numerous in the afternoon and evening with a monsoonal moisture increase, and with a cold front progressing into our counties. Somewhat cooler temperatures on tap with considerably more cloud cover and increased precipitation chances. Thursday...Cooler temperatures expected in the wake of a passing shortwave trough aloft and its associated cold front. Chances for showers and thunderstorms will likely decrease by the evening as more stable air moves into the region. Friday...Northwest flow aloft continues. Still looks like isolated to scattered showers and thunderstorms possible in the afternoon and evening with adequate low and mid level moisture. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 1117 AM MDT Sat Aug 14 2021 VFR conditions across southeast Wyoming and the Nebraska panhandle with some clouds beginning to pop up. There are thunderstorms in the forecast, but the location, spread, and intensity are all very uncertain as of right now. A low level jet will impact KCDR once again tonight into early tomorrow with gusts of 25 to 30 knots possible. && .FIRE WEATHER... Issued at 135 PM MDT Sat Aug 14 2021 Limited fire weather conditions next few days with isolated to scattered chances of precipitation coupled with lackluster winds although min RHs will teeter if not go into critical conditions. With thunderstorm chances, lightning sparked fires remain a possibility. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ UPDATE...GCC SHORT TERM...WM LONG TERM...RUBIN AVIATION...LK FIRE WEATHER...WM
Area Forecast Discussion
National Weather Service Goodland KS
609 PM MDT Sat Aug 14 2021 .UPDATE... Issued at 609 PM MDT Sat Aug 14 2021 Severe Thunderstorm Watch 440 remains in effect for most areas along and north of Highway 36. Boundary remains over the CWA from northwest to southeast, with a few storms trying to get going along it, but pulse very quickly within a few radar scans and not amounting to much. Will continue to monitor any initation along this, but the main focus will be the cluster of storms working south-southeast from west central Nebraska. && .SHORT TERM...(This evening through Monday Night) Issued at 141 PM MDT Sat Aug 14 2021 For the short term, an unsettled period of weather with chances for storms in the afternoon and evening hours through the period. Temperatures are expected to be near to slightly above average with winds remaining roughly out of the south. Synoptically, not too much is expected to change through the period. At 500mb, the area will remain in roughly northwest flow though the ridge over the Western CONUS is expected to retrograde further west as a trough develops over the East-Central CONUS. Near the surface, a boundary is currently located over the East-Central portion of the Tri-State area. This boundary will push off to the east during the day though the area will remain under an area of relatively low pressure through Sunday. Monday, the low pressure is expected to deepen across much of the High Plains. For the rest of this afternoon, a bit of uncertainty remains. First, a thunderstorm in Southwestern Nebraska has kept cloud cover over the Eastern Portion of the area close to where the boundary is. On top of keeping temperatures cooler in those areas, it may also increase stability over the area and suppress storm growth. Even so, RAP guidance suggests that there is over 2000 J/KG of both MLCAPE and SBCAPE to go with PWATs near 1.25 to 1.5 inches. Satellite also shows cumulus fields in the area. So while storms have not formed yet and there is some stabilizing due to the prior convection, there still remains plenty of ingredients for storms to form. For this evening, more uncertainty as there are multiple solutions depending on the boundary`s location, prior convection, and cloud cover. The more likely solution appears to be storms fire up along the boundary with a few isolated storms elsewhere. This would again favor locales further east in the area as the boundary slowly moves to the east. Storms would then continue for most of the night before tapering off around 3am. Another solution includes storms firing up over Eastern Colorado around sunset as a subtle shortwave moves through. The storms would move east a bit and then decay before midnight. The final solution I`ll mention and the more severe of the solution is a cluster of storms developing in North Central Nebraska that would move south during the evening. This cluster would move into the area during the early night hours and provide the area with the greatest chance of seeing severe weather with both hail and wind possible. Severe weather will be possible though with any of the solutions and favor the northern and eastern portions of the area regardless of solution. Hail, wind, and heavy rain would be possible with any severe storm. Tomorrow, the morning hours may start out with some fog or showers over the Eastern counties from the remnants of convection from the prior day. Otherwise skies will clear to allow for mostly sunny skies through the late morning and early afternoon hours. Highs are forecasted to reach the upper 80`s and low 90`s. Another chance for storms arrives during the late afternoon hours as a shortwave and lee cyclone move into Eastern Colorado. Storms would form a few hours before sunset and move east across the area, likely decaying as they go. Severe storms appear unlikely at this time as effective shear looks to be 20 kts or less though an isolated one can`t be ruled out due to the forcing from the features and CAPE above 1000 J/KG. Monday, a few showers may be possible, mainly south of I-70, but otherwise partly cloudy skies across the area. Temperatures are forecasted to remain around 90 across the area but will depend on how much cloud cover persists from the rain the prior night. Should storms develop later in the day, there does look to be a chance that a few could be severe as effective shear reaches 30 kts and MLCAPE gets above 1500 J/KG. Uncertainty remains though given the couple of days of convection prior so will continue to monitor how the environment evolves for Monday. .LONG TERM...(Tuesday through Saturday) Issued at 1241 PM MDT Sat Aug 14 2021 Upper ridging prevails at the start of the long term period, leading to warm and dry conditions on Tuesday. The quiet weather is short-lived however, with an upper trough exiting the Pacific Northwest by Wednesday. The trough closes off into a low, but guidance isn`t sure what to do with it from that point on. One solution shows the system tracking across the northern Plains while another gives it a more southerly component. Either way, this disturbance will create a wetter pattern for the region, generating chances for showers and thunderstorms Wednesday through Saturday. A cold front can also be anticipated, with the latest thinking being that it will begin to push through the area on Thursday. It is too early to determine any severe weather threat at this time. A cooling trend is forecast through the period, with highs falling from the upper 80s/low 90s on Tuesday and Wednesday to the low 80s for Saturday. Low temperatures will range from the mid 50s to upper 60s. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 500 PM MDT Sat Aug 14 2021 VFR conditions for both terminals with SCT-BKN mid and high clouds. KMCK will have VCTS from 03z-06z. Winds for KGLD, south- southeast 10-15kts. Gusts to 20-25kts thru 06z Sunday and after 14z. Winds for KMCK, south-southeast 10-15kts. Gusts to 20-25kts thru 03z Sunday and after 18z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JN SHORT TERM...KAK LONG TERM...JBH AVIATION...JN
National Weather Service Jackson KY
1110 PM EDT Sat Aug 14 2021 .UPDATE... Issued at 1110 PM EDT SAT AUG 14 2021 Storms are still rolling across our southern and southeastern counties tonight, though there has been a general weakening trend. Overall, the going forecast was in good shape. Did nudge the PoP grids some based on radar trends and recent guidance, but this didn`t lead to any substantial changes. Updates have been sent. UPDATE Issued at 920 PM EDT SAT AUG 14 2021 Stubborn strong thunderstorms continue this evening across the south. A few more are possible later this evening before the front continues to slowly cross the area from north to south. Updated Pops and sky cover to reflect the latest trends. Updates sent to NDFD and web servers. && .SHORT TERM...(This evening through Sunday night) Issued at 422 PM EDT SAT AUG 14 2021 A cold front remains just to our north, running SW and into West- Central Kentucky. Cloud cover did a good job early this afternoon with hampering convection, but with afternoon heating and clearing, scattered storms have developed along the SW bordering TN and in the north from Bath and into Fleming Co. Guidance still doesn`t have the best handle, with the HRRR much drier into the night versus a wetter solution in the NAMNEST and similar Hi-Res guidance. Because of this, have went chance PoPs through tonight before redevelopment into Sunday. Theta-e surface analysis from the RAP suggests the aforementioned front to nearly stall across the KY/OH border and through Western Kentucky. Because of this, showers will again be best along the front and in the south (where the better instability lies) into the afternoon tomorrow. An upper level high continues to sit off the Southeastern Coast, but will weaken and provide less of an influence as heights lower through the period. Shear continues to be very weak with CAPE peaking between 2000 and 3000 J/kg during the afternoon today and again Sunday. This is best along our southern counties, into Central Kentucky, and down into Tennessee. This, as well as along and ahead of the front (to our north), is where we have seen the best convection so far today. Gulf moisture continues to stream into the area with the aid of southerly flow, allowing for PWATs between 1.75 and 2". Combining this with slow storm motions, localized flooding can not be ruled out through the period. This is also highlighted by WPCs day 1, 2, and 3 marginal outlook for Eastern Kentucky. Sensible weather will feature river valley fog/stratus overnight which could hamper morning visibilties periodically. Lows will be near to slightly above average, in the mid and upper 60s. With the front at a slow crawl southward, our far northern counties (Bath to Rowan and north) will be the coolest for afternoon highs, in the upper 70s. The remainder of the CWA will generally be in the lower 80s. Lows overnight Sunday will be very similar to tonight, ranging in the mid to upper 60s. .LONG TERM...(Monday through Saturday) Issued at 321 PM EDT SAT AUG 14 2021 An active weather pattern is on tap for the extended. We can expect daily chances of showers and storms, especially during peak heating each afternoon and evening. We will have a few weather systems influencing the weather of eastern Kentucky through out the upcoming work week. A weak upper level trough will be in place across the mid west, and will slowly evolve into a slow moving closed low by mid-week. This system will provide lift for shower and storm development. There will also be a slow moving cold front that will be move around the region. Tropical cyclone Fred will also be a player, as it moves northward into the Tennessee Valley next week. The latest forecast models have Fred tracking further and further west. The northward movement of Fred`s remnants could act to further slow down the earlier mentioned cold front, keeping in place for an extended period of time over or near our area. Fred will also bring a good amount of tropical moisture into the region. All of these factor together should make for a week of active and wet weather. Rainfall amounts will depend largely on how Fred evolves, the amount of moisture we get into the region, and how much instability is available for storm formation. The latest model soundings suggest tall and skinny CAPE profiles, favorable for locally heavy rainfall. The latest QPF forecast was increased to higher numbers than the newest pure WPC QPF numbers to account for this. Temperatures should trend cooler than normal each day due to persistent and extensive cloud cover and precip, and a slight intrusion of cooler air from the north. Nightly lows continue to show a trend toward warmer than normal numbers on average. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 920 PM EDT SAT AUG 14 2021 VFR to start the 00Z TAF period. Scattered showers and thunderstorms may result in brief flight restrictions tonight. Patchy fog and lower ceilings (MVFR or lower) are possible overnight into early Sunday morning. Additional showers and storms are expected on Sunday which may result in more flight restrictions. Winds will be light and variable overnight an N/NE 5 kts or less on Sunday. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CMF/HAS SHORT TERM...BB LONG TERM...AR AVIATION...CMF
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1054 PM CDT Sat Aug 14 2021 .UPDATE... Issued at 818 PM CDT Sat Aug 14 2021 Have removed what little PoPs we had tonight up by the Alexandria area and now have a dry forecast for tonight. The RAP shows the h85 theta-e ridge and associated moisture transport remaining northwest of the MPX CWA through Sunday morning. The HopWRFs and HRRR have shifted northwest with precip for late tonight as well, so removed what PoPs we had with support in the form of forcing or CAM reflectivity forecasts now gone. && .SHORT TERM...(This evening through Sunday night) Issued at 255 PM CDT Sat Aug 14 2021 Not one cloud in the sky today with high pressure firmly in place. The center of the ridge has shifted south which has allowed surface winds to turn southerly. Despite the flow, very low dew points in the 40s are being observed area wide thanks to the source region from the high itself. Elevated fire weather conditions are occurring across central Minnesota, and have approached Red Flag criteria with gusts in the 20-25 mph range and RH values in the mid 20s. A LLJ will develop tonight across the Plains to northern MN. Better moisture contained within this flow will contribute to increasing elevated CAPE. The forcing with the LLJ and the elevated instability could lead to a few showers or thunderstorms overnight into early Sunday across west central MN. Introduced PoPs in this area as several CAMs indicate development. The loss of the LLJ after sunrise will allow storms to dissipate quickly. Elevated fire weather conditions are likely again Sunday with continued breezy south winds, slightly warmer temperatures, and min RH values in the 25-30 percent range. .LONG TERM...(Monday through Saturday) Issued at 255 PM CDT Sat Aug 14 2021 Dry, sunny weather is certain Monday and Tuesday and becoming more likely Wednesday. Highs of 80s (and perhaps a 90 in western MN) are forecast through Wednesday. Meanwhile, lows will rise from upper 50s to mid 60s Monday night to mid 60s Wednesday night. Humidity is expected to increase through mid-week as sustained southerly flow over the central Plains (to the west of a sprawling surface high over the Northeast) advects more moist air northward. Southerly winds could be breezy, especially in western MN where gusts may reach 20 knots during the afternoon. Dewpoints of mid 50s to lower 60s Monday morning will gradually rise to the low to mid 60s Wednesday morning (with some upper 60s possible in southern MN and western WI). Fire weather concerns will thus be reduced. The Pacific Northwest upper-level trough that has been mentioned in previous discussions is still forecast to eventually translate east into the Northern Plains. However, model consensus agrees that the trough`s arrival won`t be until at least Thursday, decreasing PoPs Wednesday into Wednesday night. More concerning, the trough`s evolution has become more uncertain in recent model runs. The ECMWF, GEM, and a number of EPS and GEFS ensemble members suggest that a portion of the trough breaks off into a cutoff low (at least temporarily) over the western CONUS. The rephasing of the cutoff low with the northern jetstream eventually happens but timing differs between models. Once rephasing occurs the trough moves east into the Northern Plains, developing a surface frontal system. This system should sweep a cold front through MN/WI late week, but large uncertainty when this happens exists due to the rephasing discussed earlier. (For example, a 48-hour difference in cold front arrival in MN is observed between the latest ECMWF and GEM.) With the greatest chance for widespread QPF along the cold front, the timing of greatest PoPs is in question (with later solutions suggesting Friday into Saturday). Meanwhile, the GFS is much faster, due to keeping the trough intact, leading to a Thursday to Friday timeframe. Unmentioned so far is QPF as this is also dependent on whether the MPX CWA receives a direct hit from the trough or just glancing blows. Guidance is suggesting that at least a half inch of QPF is likely, with northern MN having a good chance of upwards of an inch. Hopefully, models converge on a solution relatively soon to shed light on how much rainfall we may get. After the cold frontal passage, temperatures will also decrease with 70s for highs possible next weekend. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1054 PM CDT Sat Aug 14 2021 Move along, nothing to see here. Lots of one line TAFs with south winds and clear skies expected. Enjoy! KMSP...Winds during the afternoon will be occasionally gusty, but changes are not enough to warrant cluttering the TAF with another line. /OUTLOOK FOR KMSP/ MON-WED...VFR. Wind S 10-15 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ UPDATE...MPG SHORT TERM...Borghoff LONG TERM...CTG AVIATION...MPG
Area Forecast Discussion
National Weather Service San Francisco Bay Area
849 PM PDT Sat Aug 14 2021 .SYNOPSIS...As high pressure strengthens this weekend, Sunday should be the hottest day for inland locations and higher elevations. The weather pattern changes early next week providing the next cooling trend for the Bay Area and Central Coast as an upper trough tracks across NorCal. && of 09:00 PM PDT Saturday...A lopsided synoptic scale tug of war is underway with a broad 596dm monsoonal ridge centered 400 miles east of the Bay Area and a weaker 586dm low pressure disturbance focused 850 miles offshore to west. The center point between these two features is roughly 300 miles offshore, meaning that the broad monsoonal high pressure system is responsible for the majority of our weather, but not all. That is, the marine layer has been surprisingly robust this evening despite the relatively high pressure aloft of the region. In fact, the latest readings from the Fort Ord profiler show the marine layer has been gradually deepening and is now around 1800 feet in depth after depressing to below 1000 feet last night. So, what this mean is that despite what is a very hot and dry for most across the state, the majority of our region has been fairly seasonable and dictated by the marine layer and robust onshore flow while only the more remote locations of our forecast area such as Cloverdale, Berryessa, Pinnacles, etc are experiencing the triple digit heat much of the rest of the interior of the state is seeing today. Otherwise, evening satellite imagery is quite dynamic and features a number of interesting features, including a textbook tropical hurricane system off Baja (Linda), decaying monsoonal thunderstorms over the Sierra sending their remnants westward towards our area this evening, omnipresent wildfire smoke, marine stratus and even a band of tropical moisture farther offshore. Convective models have hinted that some of these showers and thunderstorms rolling off the Sierra in the mid level easterlies could bring a few sprinkles to our region into the morning though chances are rather slim. Per the smoke, air quality sensors across the region are running in the yellow to orange range, indicating that the stagnate air mass trapped under the high pressure system is preventing fresher air from entraining into the region. Unfortunately, even with the afternoon sea breezes, air quality struggles to improve given the amount of smoke lingering offshore waiting to be pushed inland. That said, HRRR smoke model suggests an arriving trough later early in the work week will help clear out the smoke and advect in fresher air. Looking ahead, the high pressure system over the area will peak in intensity tomorrow and very hot and dry conditions should be anticipated across the interior regions. Essentially, areas that were at least in the mid 80s today should expect another few degrees of warming into tomorrow, while nearer shore areas will see little difference. Robust onshore flow returns with tomorrow evenings seabreeze. Interior locations just beyond our forecast area will be flirting with record temperatures tomorrow and some unofficial record heat along our periphery is also possible. Needless to say, wildfire fuels are extremely dry so vigilance and caution is advised for those choosing to spend time outdoors tomorrow. Then, on Monday, the aforementioned offshore disturbance and an approaching Gulf of Alaska low will work together to suppress the high pressure system currently stagnating over us this evening before completely evicting it from the local region by Tuesday. Remnants of the ridge will then spin offshore and form an eastern Pacific high through the upcoming week while the broad 545dm low sweeps across Canada and the upper to mid intermountain west. As such, expect a trend towards a deeper marine layer and cooler and wetter conditions. Confidence is rather high on this occurring given that 5 of 5 ensemble clusters show similar scenarios playing out between days 3 and 6 with only minor to moderate perturbations in the low pressure intensity being different. && of 6:13 PM PDT Saturday...For the 00z TAFs. An amazingly resilient stratus and fog coverage /marine layer depth 1,600 feet/ continues despite last evening`s influx of tropical moisture aloft; on the heels of a strong spring to summer marine layer so far. It`s LIFR-IFR along the coast, VFR inland. The SFO- SAC pressure gradient is 3.9 mb, satellite shows onshore winds already ushering in stratus and fog. The WRF-ARW forecasts patchy light coastal drizzle overnight and Sunday morning. Wildfire smoke is limiting surface /MVFR/ and slant range visibilities. A very focused and spatially compressed 500 mb high pressure system retrogresses to the NorCal/NV border during 00z TAF cycle, expectation is this will compress the marine layer tonight and Sunday; already late we`re still waiting for the compression to show up in the profiler data. Vicinity of KSFO...VFR, west wind near 20 knots until mid evening. MVFR ceiling forecast 10z-17z Sunday, stratus intrusion hinges on the depth of the marine layer. VFR Sunday with afternoon and evening west wind 20 knots. KSFO Bridge Approach...Similar to KSFO. Monterey Bay...IFR due to stratus and fog around the Monterey Bay already making inroads into the northern Salinas Valley. VLIFR-IFR in stratus and fog, the marine layer likely compressing tonight and Sunday. Patchy light coastal drizzle possible overnight and Sunday morning. Conditions improving to MVFR-VFR late Sunday morning and afternoon. && of 02:10 PM PDT Saturday...Breezy north/northwest winds persist today through Sunday. Stronger gusts will be observed along the coast where coastal jets commonly set up (e.g. Big Sur Coast, Point Reyes, etc). In addition, gusty westerly winds will funnel through the Golden Gate and into the Delta during our afternoons and evenings this weekend. These winds may be hazardous for smaller vessels. As for the sea state, it continues to be driven by a weak southerly swells from the remnants of a tropical system and a northwesterly swell stemming from a low pressure off the coast of British Columbia. Are observing steep northwest wind waves that are typical for this time of the year as well. Stronger northwest winds develop early next week as the low pressure begins to approach the Pacific Northwest. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...SF Bay until 9 PM SCA...Pt Reyes to Pigeon Pt 0-10 nm until 9 PM SCA...Pigeon Pt to Pt Pinos 0-10 nm until 9 PM SCA...Pt Arena to Pt Reyes 0-10 nm SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm && $$ PUBLIC FORECAST: DRP AVIATION: Canepa MARINE: Diaz Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service Nashville TN
1012 PM CDT Sat Aug 14 2021 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Issued an evening update to further reduce pops. Latest Hrrr indicates that the decreasing convection trend overnight will continue. Otw, dewpoint spreads at or below 5F. That, combined with the usage of the fog formatter both indicate the development of patchy fog late tonight. Will therefore maintain the inclusion of patchy fog. Min temp forecast appears to be on track so no other changes. && .AVIATION... 00Z TAF DISCUSSION. Scattered showers and a few storms were in Middle TN this evening. Most of the activity was near a southward moving outflow boundary that stretched from Centerville to Murfreesboro at 00Z. The convection should dissipate by 03Z. Expect areas of low clouds and some vsby restrictions to develop later tonight into early Sunday at all terminals. Best chance for greatest impact is at KCSV due partly to the heavy rains that fell in that area from a late afternoon storm. The areas of low clouds and fog will burn off by mid morning Sunday...with another round of scattered showers and storms expected to commence early Sunday afternoon. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......21 AVIATION........Vannozzi
Area Forecast Discussion
National Weather Service Phoenix AZ
404 PM MST Sat Aug 14 2021 .UPDATE...Updated aviation discussion. && .SYNOPSIS... High levels of moisture will remain entrenched across the Desert Southwest through the middle of the week, leading to persistent chances for showers and thunderstorms. The primary threats with any storms remain localized heavy rainfall that may cause flash flooding. A Flash Flood Watch is in effect for south-central Arizona through Sunday afternoon. Strong winds and some blowing dust will also be possible for desert locations. With increased cloud cover and showers, temperatures will remain below normal. && .DISCUSSION... A very moist airmass remains in place across the region today. Mesoscale analysis shows regional PW ranging from ~1.4-1.9"+ with the 12Z PSR sounding showing PW of 1.77" and a late morning PHX ACARS soundings indicating a comparable mean PW of 1.8". The 12Z sounding also featured a worked-over, more stable column with a near moist adiabatic profile,relatively weak CAPE and moderate CIN. Though significantly higher MUCAPE was developing midday and back in the 1000s as shown on the RAP and ACARS, although with CAPS also present. The UL pattern depicted pronounced E flow aloft along the S flank of the UL ridge with the latest inverted trough and vort max over S-E AZ with additional disturbances lined up over S NM/W TX to the east preparing to ride the easterly flow conveyor belt into the region. METSAT showed mostly cloudy to patchy clear conditions as radar painted scattered showers and thundershowers across SE-E AZ and into Pinal County SE of Phoenix. After last night`s widespread storms dewpoints remained very high from the upper 60s to mid 70s in the early afternoon along with enough breaks in the clouds to produce increasing afternoon insolation and heating around Phoenix and the lower deserts. HREF members have divided into two camps for this afternoon and tonight. The ARW and the HRRR favor a smaller area of storms descending from S Gila Cty into the SE-S-Central Valley while weakening as they enter the Valley this evening around 8-9PM MST. In the other camp are the significantly more bullish NSSL, FV3 and NAM NEST which favor more numerous, robust storms over a larger area descending off the E high terrain and not weakening as much as they cross Phoenix. The UL triggering mechanism disturbances in place support the latter/stronger storm scenario, while the possible lingering effects of a recently worked-over column support the former/weaker storm scenario. In either case there remains a good 40% NBM chance of precipitation tonight and a 50% chance of HREF thunderstorm wind gusts of >35 mph across Phoenix and the deserts tonight. There`s also almost a 10% HREF chance of thunderstorm wind gusts of 60 mph tonight across the lower deserts. The current upper level pattern changes very little on Sunday and into the early part of the week. As a result a flash flood watch remains in effect for the region (not including SW AZ and SE CA) through Sunday afternoon at 5 PM MST. Temperatures today and for the week will also change very little and remain below normal, in the upper 90s to near 100, owing to the persisting highly humid airmass conditions. The Clusters family favors similar flavors of a large, weak low pressure trough anomaly dominating the Intermountain West and N. Rockies by the middle of the week as well as disturbances and associated storms lifting out ahead of it across Phoenix and the AZ area. As a result expect elevated chances of storms and precipitation through the middle of the week. && .AVIATION...Updated at 2305Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Still some potential for shower/thunderstorm activity across parts of the Phoenix metro area this evening, with higher chances for an outflow moving through. Still some uncertainty as to how widespread any activity will be given that the air mass is slightly more stable compared to yesterday. Winds from east to northeasterly outflow are expected to arrive near or after 02Z, with gusts of 20-30 kt possible. Otherwise, easterly winds should persist overnight into much of Sunday morning. Expect SCT-BKN clouds to persist mostly aoa 6 kft, though cigs could drop down with any convection that develops over the metro later. Southeast California/Southwest Arizona including KIPL and KBLH: At KIPL, light winds should persist out of the east to southeast for the bulk of the TAF period, while winds are expected to remain southerly for KBLH. FEW-SCT clouds aoa 12 kft are expected to persist throughout the period. && .FIRE WEATHER... Monday through Friday: Humid conditions will continue through much of the week. The threat of showers and thunderstorms will also continue through midweek, followed by a drying trend and only a slight chance of wetting rains. The strongest storms early in the week will be capable of producing localized flash flooding, particularly in the higher terrain north and east of Phoenix. Below normal temperatures are also anticipated. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Flash Flood Watch through Sunday afternoon for AZZ534-537>563. CA...None. && $$ DISCUSSION...Sawtelle AVIATION...Rogers/Smith FIRE WEATHER...Hirsch
Area Forecast Discussion
National Weather Service Pueblo CO
332 PM MDT Sat Aug 14 2021 .SHORT TERM...(This evening through Sunday) Issued at 330 PM MDT Sat Aug 14 2021 ...Showers and storms possible all locations tomorrow afternoon... ...Smoke will be increasing again during this period... Currently... A couple of isolated showers were noted over the region at 2 PM. A few showers were noted along the DCVZ ()well defined in radar data) extending from Elbert county into El Paso county. Other very isolated showers were noted over the high terrain. Otherwise skies were predominantly clear across the area. Rest of today and tonight... Water Vapor sat pix imgy shows rather very dry conditions over the region and this will lead to a decrease of thunderstorm activity over the region during this period. Best chance of storms will mainly be over the mtns, especially along the CONTDVD region. Some rain could be heavy but given entrainment of the drier air any heavy rain should be brief. Likewise any flash flood threat will be low. Overall a large majority of the region will be dry the rest of today through tonight. A review of the HRRR smoke fcst indicate smoke will be on the increase across the region tonight, especially smoke aloft. Expect vis to gradually decrease with time. Temps tonight will be seasonable with mins around 60F plains and 40s and 50s higher elevations. Tomorrow... Pattern will be a bit more active, and all areas will see the potential for showers and storms. Two potential features will help bring a better chance of precip to the area. First, flow aloft will transition to NW and a weak wave is noted in the mid to upper levels moving over the fcst area. The 2nd feature (not shown by ALL guidance) is an MCV feature developing at 700 mbs developing over the plains. Mainly the CAMS show this feature developing. Overall expect a better chance of storms affecting all areas tomorrow, albeit the brunt of the precip on the plains will likely occur after this period (after 00 UTC). CAPE values are not all that high and storms should be moving at a decent clip to the southeast, so flash flooding should not be that great of a concern, on the other hand the rain will be heavier that we have seen in the previous 24 hours so the flash flood threat will be with us, albeit low. Storms are not expected to be severe, but locally strong gusty winds and some small hail will be possible. Smoke will continue to increase, especially at mid level, so anticipate hazy conditions tomorrow. /Hodanish .LONG TERM...(Sunday night through Saturday) Issued at 330 PM MDT Sat Aug 14 2021 ...Flash Flooding could be an issue for the burn scars areas on Monday during the afternoon and throughout the early evening, especially for the Spring burn scar... For Sunday night through Monday...thunderstorms that had developed during the evening will continue overnight over some areas, especially over the eastern plains. During the morning hours on Monday, there will be thunderstorms possible over the far eastern and southeast plains. Scattered thunderstorms will develop during the late morning, mainly over the San Juans and southern Sangre de Cristo Mountains. These storms will move out over the I-25 corridor areas during the afternoon and evening hours. Isolated thunderstorms will be possible over the plains, with the best chance of occurrence over the Raton Mesa area and the southeast plains later in the evening. For Tuesday...a few isolated thunderstorms could develop over the central mountains. For Wednesday...scattered thunderstorms will develop over the central mountains during the afternoon and over the eastern mountains and northern plains during the evening hours. A slight chance of severe thunderstorms over the eastern plains late evening. For Thursday through Friday...Scattered thunderstorms will develop throughout the afternoon over the mountains and evening over the plains. Showers and thunderstorms will continue into the late evening hours over the plains and into Friday morning. Some of these storms could be severe. Isolated to scattered thunderstorms will be more likely over the far eastern plains on Friday and there could be severe thunderstorms during the afternoon and evening hours, especially over Prowers and Kiowa counties. A few thunderstorms will also be possible over the Rampart Range, Palmer Divide, and the Raton Mesa area and could potentially become severe in these areas as well. Detailed discussion: Sunday night through Monday... There is going to be some troughing to the east of the CWA and moisture begin advected upstream over the area at the 700-500mb level which will produce thunderstorms initially over the mountains and then moving out over the plains during the evening hours going into the late Sunday evening hours. Some flash flooding could be possible for the burn scar areas throughout the early part of the evening, especially for the southern Sangre de Cristo Mountains, to include the Spring burn scar. Convective models do suggest a possible development of an MCV late tomorrow evening and going into early Monday morning, SREF/NAM12/GFS20 are all showing a lot of moisture hanging out during the Monday morning hours over SE Colorado and therefore showers and thunderstorms could still be continuing into the morning hours over the far east and southeastern plains. There could be a slight chance of a severe thunderstorm over Kiowa county towards the center of the MCV where there is more omega forcing. There will be thunderstorms developing over the mountains again, during the afternoon, with the best chances for development along the eastern mountain ranges in the late morning hours. A few storms could move out into the plains later in the afternoon and evening, especially along the I-25 corridor. It will begin to slightly cool as the northwesterly flow is persistent over most areas with troughing to the east, with temperatures closer to the seasonal average. Tuesday through Wednesday... Ridging will temporarily build back in with most of the CWA remaining dry as the monsoonal moisture plume remains further to the west, and only some afternoon and evening thunderstorms will be possible over the central mountains. Temperatures will also be back on the rebound, with anywhere from 5 to 10 degrees above the seasonal average over most areas, especially for Wednesday, where triple digit heat can be possible over some areas of the lower Arkansas River Valley. By later in the day on Wednesday, troughing is going to allow for some of the monsoonal moisture plume to be drawn up from the southwest and there could be some more storm development towards the north and allow for a slight chance of severe thunderstorms to move in over the north areas of the plains by late evening, but all depends on the timing of the boundary interacting with the southerly moisture surge ahead of the trough. Thursday through Friday... Most of the ensembles and deterministic models are in relatively good agreement with a trough and associated closed low at the 500 mb level moving over the region late Thursday evening and going into Friday. This could potentially be a very impactful system, with a strong boundary that could produce severe thunderstorms over the eastern plains of the CWA by late Thursday evening and Friday as well. This system will need to be continued to be monitored in the days ahead to determine when and where exactly the frontal boundary associated with this trough will be moving over the CWA and the timing. Along with the threat of severe weather, will also be a reinforcement of cooler temperatures over the area, which will allow for maximum temperatures to be slightly below the seasonal average by Friday. Stewey && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 330 PM MDT Sat Aug 14 2021 VFR conditions are anticipated during the next 24 hours at all 3 taf sites, KPUB, KALS and KCOS. There will an increasing chance of thunder at all TAF site starting late tomorrow afternoon and especially tomorrow evening, so later fcst may need to introduce thunder into the TAF fcst products. Winds overall will be diurnally driven during this period, however gusty outflows associated with TSRA will likely affect the TAF sites starting late tomorrow afternoon. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...HODANISH LONG TERM...STEWARD AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Las Vegas NV
828 PM PDT Sat Aug 14 2021 .SYNOPSIS...A strong area of high pressure centered over northwest Nevada will lead to above normal temperatures through Monday. A lingering moist and unstable air mass will continue to produce isolated afternoon thunderstorms over the mountains of southern Nevada and southeast California and better storm coverage over northwest Arizona through Tuesday. Drier southwest flow and cooler temperatures are expected to spread over the region after Tuesday. && .UPDATE...Earlier isolated severe thunderstorm over the plateau of northern Mohave County has weakened. However, outflow from that storm just reaching eastern Lake Mead with 20-35 mph wind gusts likely from South Cove to Temple Bar and Overton Arm. Also, we have been monitoring thunderstorms over southwest Lincoln and northwest Clark counties. Those storms are capable of producing wind gusts up to 50 mph and brief heavy rain. Did a quick refresh of Pops for the rest of tonight using latest camPoPs. No other changes. && .PREV DISCUSSION...230 PM PDT Sat Aug 14 2021 .SHORT TERM...through Monday. Thunderstorms developing over northern Lincoln County and southwest Utah will tend to propagate toward the south-southwest late this afternoon. However, low MLCAPE values and MLCIN persisting into early evening should lead to cells dissipating before they reach Clark County. There is still better potential for more sustained convection moving from northern Mohave and western Yavapai counties toward central Mohave late this afternoon and evening. This is indicated by the latest HRRR and HREF. A similar setup remains in place for Sunday afternoon and evening where only isolated thunderstorms over southern Nevada will primarily be confined to the mountains and central/southern Mohave County should see storms moving in from the rim country during the late afternoon and evening. This pattern is driven by the clockwise circulation around the high pressure centered over northwest Nevada. This high will bring a couple days of above normal temperatures, especially over southeast California and southwest Nevada which prompted the Excessive Heat Warning which will be in effect for Inyo, western San Bernardino and southern Nye counties from 10 AM Sunday until 8 PM. The center of the high will be nudged down over southeast California and southern Nevada on Monday ahead of a broad trough dropping into the Pacific Northwest and Great Basin. This provide will provide one last day of above normal temperatures and may suppress convection somewhat with increasing temps aloft and a dry northwest to northerly flow. .LONG TERM...Tuesday through Saturday. The setup is now looking less favorable for deeper moisture to be drawn into our region ahead of the aforementioned approaching trough though lingering moisture should remain over part of southern Nevada and northwest Arizona and maybe eastern San Bernardino County. There should still be sufficient instability over these areas for afternoon thunderstorms Tuesday and possibly again Wednesday and this is reflected by the latest NBM PoPs which indicate more than just terrain-based storms. However, the ECMWF and GEFS ensemble means have been digging the base of the trough a little deeper resulting a drier southwest flow which could scour moisture out to the east during the Tuesday-Wednesday period followed by a persistent dry west to northwest flow Thursday into next weekend. The ensemble-based NBM PoPs are a little slow at indicating this drying trend so far, but temperatures decrease several degrees after Tuesday under the influence of the trough and PoPs will likely trend downward over the next few model runs if ensembles continue to dig the trough slightly farther south. && .AVIATION...For McCarran...Light easterly winds are favored through early evening before a trend toward more south or southeasterly winds arrives late in the day. A few gusts in the 12-18 knot range are possible with the southerly wind shift. Otherwise, just scattered mid and high level clouds expected, with isolated thunderstorms possible mainly east of Lake Mead, impacting the Peach Springs approach corridor. For the rest of southern Nevada, northwest Arizona and southeast California...Outside of thunderstorm influences, mainly light and diurnal winds are expected at the regional TAF sites. Scattered to broken mid level cloud cover is likely across much of the region, with isolated evening thunderstorm activity mainly in northwestern Arizona. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Pierce SHORT TERM/LONG TERM...Adair AVIATION...Outler For more forecast information...see us on our webpage: or follow us on Facebook and Twitter