Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/10/17

Area Forecast Discussion
National Weather Service Bismarck ND
943 PM CDT Sat Sep 9 2017 .UPDATE... Issued at 937 PM CDT Sat Sep 9 2017 Latest radar loop shows a lone shower lifting northward and possibly clipping far southeast Dickey county. Remaining shower activity should remain east of the CWA. Will remove mention of thunder southeast and keep a mention of a shower for the next hour over southeast Dickey county. Mesoscale models are still not picking up on a strong signal for fog over central ND tonight. HRRR/RAP are indicating some patchy fog in the southern Missouri River Valley and east toward Jamestown. Already a mention of patchy fog and may spread it just a bit farther east, but no additional changes at this time. UPDATE Issued at 633 PM CDT Sat Sep 9 2017 Moderate southerly flow continues over western and central ND early this evening ahead of surface low pressure over eastern Montana. Warm advection clouds/showers over eastern South Dakota with a stray shower pushing northward through Dickey county. Could still be a few showers or possibly an isolated thundershower over the next few hours. This was covered in the previous forecast but made some minor adjustments here for clouds and pops. Otherwise no changes other than populating latest sensible weather elements and interpolating to mid evening values. && .SHORT TERM...(This evening through Sunday) Issued at 309 PM CDT Sat Sep 9 2017 Sunny conditions this afternoon per latest visible imagery. An upper low circulating over central/eastern South Dakota continues to push scattered mid level clouds into Dickey County at this time. Regional radar shows a band of showers south of Aberdeen, South Dakota trying to push north. The HRRR/RAP simulated composite reflectivity`s still lift some higher reflectivity`s into Dickey and LaMoure counties late this afternoon and evening. A slight chance for showers/thunderstorm remains in the forecast until 06z Sunday. Have also mentioned patchy fog/low clouds mainly southern ND once again developing between 09z through 15z Sunday, as the HRRR/RAP13 hint at this with a continuation of southeasterly winds. Farther upstream, current surface observations and satellite imagery indicate a large area of surface smoke and reduced visibilities from Lewistown to Havre Montana, and into Medicine Hat in Alberta Canada. With a cold front pushing through eastern Montana late tonight, and into northwestern ND by mid morning Sunday, winds will shift to the west/northwest. As a result, a concentration of smoke, albeit lighter, will filter into the western ND, per NDFD Air Quality Forecast and HRRR near surface smoke and vertically integrated smoke (aloft). The smoke aloft will likely spread into central ND Sunday afternoon and evening. Have incorporated this mention into the gridded forecast through Sunday evening. For Sunday, the aforementioned cold front will move west to east, reaching the James River Valley Sunday evening. Frontal passage both in advance and behind the front during the day Sunday looks dry, thus will maintain a dry forecast. Highs Sunday will be in the mid to upper 80s. .LONG TERM...(Sunday night through Saturday) Issued at 309 PM CDT Sat Sep 9 2017 A warmup through midweek, then a sharp cool down Friday and Saturday per the latest PNA/Pacific North American Teleconnection Pattern. The PNA ensemble mean forecasts coincide rather strongly together with each other as the mean value of the PNA index drops below zero briefly around Sep 16th. This indicates a potential cool down, and is further verified with both the GFS and ECMWF 850mb temperatures falling to +2C to +6C Saturday. Thus after a dry and warm forecast Monday through Wednesday with high temperatures in the 80s to lower 90s, a gradual cool down occurs Thursday through Saturday, with highs in the 60s Saturday. In addition, chances for showers/and some thunderstorms increase daily Wednesday through Saturday, along and ahead of the cooler temperatures. The main baroclinic zone/upper trough shifts into western and across central ND Friday/Friday night. This represents the time period for the highest chances of showers. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 937 PM CDT Sat Sep 9 2017 VFR conditions to begin the 00Z TAF period. Expect VFR conditions throughout except for a period of possible fog around 10-16 UTC as has been the case the past few days. The for this morning was mainly along and west of the Missouri. Sunday morning indications are the most likely areas would be central ND into the James River Valley. Short term models are not indicating much in the way of low stratus/fog at this time but given the persistent pattern and low T/TD spreads expected around 12 UTC by BUFKIT forecast soundings, we added a VCFG at KBIS and KJMS to start, and will continue to monitor. Southerly flow will shift west to northwest from west to east behind a cold front during the day on Sunday. There were some restrictions to visibility over Montana today due to smoke. Will need to monitor for possible restrictions in west/central ND due to smoke behind the cold front. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TWH SHORT TERM...KS LONG TERM...KS AVIATION...TWH
National Weather Service Eureka CA
329 PM PDT Sat Sep 9 2017 .SYNOPSIS...High pressure will bring warming and drying through Monday. An offshore trough will bring a chance of showers and thunderstorms around Tuesday. Seasonable weather conditions will prevail through the remainder of the week. && .DISCUSSION...Ridging aloft and associated subsidence will continue to build over the area through Sunday as a cut-off low meanders about offshore the central/southern California coast. High temperatures were warmer today. Additional warming is expected for Sunday as an offshore flow pattern emerges. Highs in the interior valleys will climb into the 90s and peak around 100F. Coastal areas should warm as well on Sunday as the stratus burns off. Current indications are for coastal highs to peak in the upper 60s to mid 70s. The offshore flow will strengthen Sunday night thru Monday and temperatures will warm a few more degrees most everywhere. The GFS and NAM indicate broad southeast flow aloft with an increase in high and mid level RH on Mon, mainly across the southern and eastern portions of the forecast area. The high layered clouds may knock temps down and reduce the potential for additional warming on Mon. A new upstream trough in the westerly flow will interact with the central/southern California cut-off low on Tuesday. The best opportunity for showers and storms appears to be on Tue or Tue night as deeper moisture and instability combine forces with the trough. The models continue to trend faster with ejecting the cut off low eastward and out of the area on Wed. The upstream kicker may generate some mountain showers Wed or Thu, however the threat for additional t-storms is too low to worry about at this time. Overall, we are looking at seasonable weather conditions with near normal temperatures through much of next week. && .AVIATION...A deep stratus layer impacted the north coast and interior valleys this morning. Interior valley clouds eroded quickly with daytime mixing while improvement has been slow along the north coast this afternoon. Mendocino County, on the other hand, had minimal cloud coverage with mostly VFR conditions throughout the day. KCEC should remain VFR with scattered skies the next few hours into the evening. The Humboldt Bay area should slowly scatter the next few hours with KACV and KFOT possibly seeing a short period of blue skies around 4 to 5 PM this evening. Expect stratus to return to Humboldt Bay tonight bringing IFR to LIFR conditions. A combination of increasing north winds over the waters and dry easterly flow inland will help keep clouds out KCEC through most of the night. However, a wind shift could allow low ceilings to impact the airport late tonight thus I just hinted at the possibly with a scattered deck in the TAF. Otherwise, the Humboldt Bay area should observe a return of low ceilings and visibility tonight with improving conditions for Sunday afternoon. /KML && .MARINE...The 11 AM ASCAT pass this morning confirmed fresh winds across the southern waters ranging from 22 to 27 kt while winds to the north were around 10 to 15 kt. North winds will continue to increase tonight through Sunday with more widespread 20 to 25 kt winds offshore and gusts around 30 kt. The HRRR seems to be capturing current conditions fairly well so it was used for the near- term wind forecast. Gusts to 30 kt will produce some steep wind driven waves nearshore primarily around Cape Mendocino. Then an approaching surface low will cause winds to weaken from south to north bringing widespread gentle winds and southerly flow off the Mendocino County coast Monday and Tuesday. The confidence in the winds for later next week becomes low as models have been having the tendency to over forecast the winds. That said, high pressure across the northeast Pacific Ocean will bring a return of increasing northerly flow. As far as the wave environment, it`s looking more and more like summer is coming to an end with persistent northwesterly swells expected to impact the waters through next week. Otherwise steep wind driven waves will build through Sunday and settle early next week. An advisory was issued for marine zone 455 to account for gusty winds and steep waves that propagate nearshore. /KML && .FIRE WEATHER...Primary concern through Monday will be light to moderate offshore flow along with drier humidities each night/day. The NAM12 has 925mb winds reaching 15-20kt tonight into Sunday morning over zones 201/203, however RH`s are forecast to remain above critical fire weather thresholds throughout the forecast area. More robust easterly flow with stronger drying is forecast to develop Sunday night into Monday morning throughout the forecast area. Once again the strongest easterlies (15-25kt at 925mb per the NAM12) will be over zones 201-203-204. Thus expect gusty easterly ridge level winds around 30-35mph Sunday night for the usually breezy mountain peaks. RH`s are forecast to remain moderate til 6z-15z Monday when boundary layer RH`s plummet to 20%-30% throughout the forecast area, but with generally light easterly ridge level winds from 5 to 10kt. We will continue to highlight the potential for critical fire weather conditions for all zones above 3000 feet. A red flag warning will not be necessary. As for t-storms, the models continue to show the best potential for storms and showers spreading northward into our neck of the woods Monday night and/or Tue/Tue Night. The trend has been for an upstream kicker to eject the central California cut-off eastward out of the area on Wed. We may still see some showers over the mountains even with the drier westerly flow aloft Wed or Thu as a s/w trough drops down from the NW. The threat for storms with this s/w trough is too low to be a source of worry at this time. The upshot, temperatures will be seasonable (about normal) and subjectively pleasant through much of next week. && .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory until 11 PM PDT Sunday for PZZ470-475. Small Craft Advisory until 9 PM PDT this evening for PZZ455. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Green Bay WI
1029 PM CDT Sat Sep 9 2017 Updated aviation portion for 06Z TAF issuance .UPDATE... Issued at 858 PM CDT Sat Sep 9 2017 Lowered temperatures across far northeast Wisconsin tonight and increased the areal coverage of patchy frost over that region. Only went with middle 30s for lows, so will hold off on a frost advisory and just cover the situation with HWO/SPS. && .SHORT TERM...Tonight and Sunday Issued at 236 PM CDT Sat Sep 9 2017 The latest RAP analysis and satellite/radar imagery show high pressure centered over the central Great Lakes. Southeast flow off Lake Michigan has support a widespread cu field, which turned broken for a short period late this morning. A weak shortwave is moving over the northern Plains, but is running into a blocking ridge over the Great Lakes. With the surface high remaining over the region, clouds and temps are the main forecast concerns. Tonight...High pressure will remain over the region. Will see clouds dissipate with sunset, but a few clouds may arrive late tonight over north-central as recycled moisture pushes in from the southwest. May also see a few strands of strato-cu push in off Lake Michigan into east-central WI towards morning. Temps continue to look warmer than last night, though will probably see a few upper 30s over northern Forest, Vilas, and Florence counties. Otherwise, lows mainly in the 40s. Sunday...A shortwave will be moving into the northern Mississippi Valley, but will likely remain too far west of the area for much impact on our weather. Low level flow will turn more southerly, which should continue to support more cu formation over eastern WI, while scattered cu should also pop over the western edge of the area. With the southerly breeze, temps will continue to warm into the upper 60s to middle 70s. .LONG TERM...Sunday Night Through Saturday Issued at 236 PM CDT Sat Sep 9 2017 A long period of dry weather looks likely for Wisconsin, with summer like conditions possible by the middle of the week, as an upper ridge builds across the Great Lakes between the westerlies to the north and the upper low that is formed after the hurricane comes ashore and weakens. High and low temperatures may be ten or more degrees above normal, with humidity rising as well. With the waters of the lake and bay still in the mid 60s, it might be warm enough to swim. && .AVIATION...for 06Z TAF Issuance Issued at 1025 PM CDT Sat Sep 9 2017 Mostly clear skies are anticipated overnight. The exception may be some lake-enhanced clouds along the Lake Michigan shoreline late tonight. These may linger into the morning at the MTW TAF site, where brief MVFR ceilings may occur. Patchy MVFR/IFR fog may also form late tonight, especially in north central and northeast WI. Few to scattered cumulus should reform across the region by late Sunday morning. South winds will also pick up a bit on Sunday, with gusts to 15 kts in north central and central WI, and along the Lake Michigan shoreline. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE.........Kieckbusch SHORT TERM.....MPC LONG TERM......RDM AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Pocatello ID
252 PM MDT Sat Sep 9 2017 .DISCUSSION... Main forecast concern today is the potential for showers/t-storms. Sufficient moisture is in place per surface obs. Our primary source of lift will once again be terrain, but a weak wave/trough brushing the region may also contribute. T-storm outflow boundaries will also provide lift and help to make up the difference in areas such as the Snake Plain. Instability is sufficient for thunder but otherwise looks fairly marginal, although the NAM generates CAPE values of 500- 800 J/kg over the central Mntns and W portions of the Southern Highlands, and some downdraft CAPE is available. Thus, our severe weather threat today is once again very low. Similar to yesterday, the strongest cells may produce wind gusts over 40 MPH, and to a lesser degree, perhaps some small hail. High temps today should approach yesterday`s values, but may be just a few degrees cooler due to cloud cover/storms. Most of the short-term models also show an area of precip moving NNE across eastern portions of the forecast area overnight tonight. Confidence is low on exactly how this may evolve, but have added a chance of precip. A lingering shower/storm will be possible Sun afternoon near the WY border, but otherwise high pressure is still on track to build across the region Sun-Tues AM with dry weather. Long range guidance continues to signal a significant change in our weather pattern. A closed low pressure system is forecast to move into CA Wed and then collapse into a trough/front that will push into our region/wash out by Thurs AM. This trough/former low will actually be rotating around an even stronger storm system moving ESE into OR/WA late Thurs, moving E across ID with an associated stronger cold front Thurs night/Fri AM. There are still notable differences between the models on exact timing of precip/placement of heaviest totals, but confidence is increasing that this will be a strong system with the potential for widespread showers, storms, and areas of rain. Have continued the trend of increasing PoPs from Tues eve right through Fri night/Sat morning region-wide, highest Wed eve- Thurs eve. High temps may not make it out of the 50s (mountains) and 60s (Snake Plain) by Fri. Stay tuned! - KSmith/Valle. && .AVIATION... Showers and thunderstorms remain in the forecast. We have VCSH or VCTS through this evening at all TAF sites. VFR weather is expected although with heavier rainfall, we could drop to MVFR/IFR briefly. Gusty winds over 25kts are possible with stronger storms as well. We kept VCSH overnight at KIDA and KPIH as a wave lifts north across far eastern Idaho. There is actually some potential of dropping to MVFR/IFR due to ceilings if we can get some good rain going to moisten things up some more. For KDIJ, that potential for showers and lower ceilings extends into Sunday. - Keyes && .FIRE WEATHER... Showers and isolated/widely scattered thunderstorms will continue into this evening. A weaker wave moves north near the Wyoming border overnight, keeping showers going across portions of the Snake Plain and eastern highlands. Thunder is NOT expected overnight but we wouldn`t be surprised if a strike or two occurred. For Sunday, drier air starts moving in BUT we are expecting enough moisture for isolated storms over the highlands especially east of I- 15. High pressure builds for Monday and most of Tuesday shutting off showers/storms. By Tuesday evening and beyond, expect a pretty decent storm to drop south out of Canada. This will bring much cooler weather our way and a better chance of precipitation for the middle and end of next week. - Keyes && .AIR STAGNATION... S to SW winds and increased moisture have reduced smoke levels significantly in SE Idaho over the past 24-36 hrs. Visibilities have increased to greater than 10 miles at all of our visibility- reporting surface ob stations, and the latest monitoring from Idaho DEQ shows air quality readings have improved to the "Good" category across almost the entire forecast area. A review of regional webcams does show some lingering smoke across portions of the Central Mntns, where air quality values may still be "Moderate". A chance of t-storms today (both their associated moisture and local outflow winds) along with continued S to SW winds will continue to help slowly reduce the smoke. Forecast confidence remains high in this scenario. We do expect some smoke will linger in the Central Mntns due to their proximity to several active wildfires, and isolated lingering patches of smoke are possible in other parts of our region, so we are maintaining mention of "patchy" smoke across the entire forecast area ("areas" for Central Mntns). Beyond today, the NAM/GFS both continue to advertise winds in the mid-levels of the atmosphere will turn into the W Sun AM and WNW Sun night, which MAY push some more smoke into portions of our region (especially the Central Mntns) as dozens of large, active wildfires continue across the NW. Guidance from the HRRR Smoke Model and AIRPACT-5 from Washington State University hint at this trend, but it should be noted that guidance at this time looks nothing like what we experienced over the past week. All in all, forecast confidence is fairly low in smoke evolution beyond Sunday, and for now we will maintain the ongoing mention of smoke in the forecast region-wide for the first part of the upcoming week. - KSmith/Valle && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Pueblo CO
313 PM MDT Sat Sep 9 2017 .SHORT TERM...(This evening through Sunday) Issued at 313 PM MDT Sat Sep 9 2017 Most showers/tstms this evening are expected to be over and near the higher terrain. However, the NAM and HRRR continue to show some storms moving east over the I-25 corridor and maybe even a little farther east, especially in Las Animas county. By late night, most if not all of the pcpn should end. A weak disturbance in the flow is expected to move over western CO late tonight and then make its way slowly over central Colorado on Sun. This disturbance could help kick off some showers/tstms in the mid to late morning hours over the central and portions of the southwest mtns. Then more showers/tstms will develop in the afternoon hours over and near the higher terrain. The models also suggest that some storms could again move out along the I-25 corridor. Temps will still be above average acrs the southeast plains, with highs on Sun mostly in the mid 80s to lower 90s. In the San Luis and Upper Arkansas Valleys, highs will be around average with readings in the 70s. .LONG TERM...(Sunday night through Saturday) Issued at 313 PM MDT Sat Sep 9 2017 Sunday night through Tuesday...Upper level ridge is forecast by all models to remain anchored over the area, providing weak flow aloft. Mid and upper level moisture remains trapped in the ridge, so there will be daily chances for afternoon and evening showers and storms, mainly across the high country and adjacent terrain. A weak front will move across the eastern plains early Monday, bringing weak upslope flow and increased low level moisture to the plains. Temperatures on Monday and Tuesday will be above seasonal levels in the 80s to lower 90s across the lower elevations and mainly in 60s and 70s across the higher terrain. and Tuesday. Wednesday through Friday...A deep upper trough moving into the western US early Wednesday will push the upper ridge south and east through the period. Southwest flow aloft increasing across the region into the end of the week, as the broad trough moves out across the Great Basin and Northern Rockies. There are some differences in location of the trough, but models in concurrence with keeping daily chances of showers and storms across the higher terrain. We may have decreasing chances of precipitation across the eastern plains, as low level moisture decreases with southwest flow aloft. Temperatures look to be at or slightly above seasonal levels through the extended period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 313 PM MDT Sat Sep 9 2017 VFR conditions are expected the next 24 hrs at KCOS, KPUB and KALS. All three forecast sites will also have the potential for showers/tstms in the vicinity this evening and again late Sun afternoon. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...28 LONG TERM...TM AVIATION...28
Area Forecast Discussion
National Weather Service Sacramento CA
300 PM PDT Sat Sep 9 2017 .SYNOPSIS... Warming trend with showers and thunderstorms possible over portions of the mountains through early next week. Cooler with more widespread showers and thunderstorms possible toward the middle of next week. && .DISCUSSION... Water vapor imagery showing upper low digging south along 123 W this afternoon. Some cu/tcu has developed over the mountains with a few isolated weak storms over the Sierra Nevada. Expect this to be the main area of development into early evening per latest HRRR runs. Afternoon temps running about 2 to 7 degrees warmer than yesterday at this time and expected to max out slightly above normal. Upper low forecast to remain offshore and drift slowly south to about latitude 32N Sunday then gradually meander back northward early next week. Interior NorCal will warm over the weekend as the low drifts farther away. Highs Sunday/Monday will be in the upper 90s in the Central Valley with triple digit heat in the Northern Sacramento Valley. Main threat of afternoon showers or thunderstorms will be over the Sierra Nevada, mainly south of I-80 Sun. Threat spreads farther north Monday to include Coastal Range and mountains of W Plumas and Shasta as the low approaches again. Upper low progged to be near the Central Coast again by Tuesday and slightly deeper. This will result in some synoptic cooling over Interior NorCal along with the possibility of more widespread showers and thunderstorms. PCH && .EXTENDED DISCUSSION (Wednesday THROUGH Saturday) Forecast remains on track as models indicate the persistent upper low finally tracking inland across central California on Wednesday. As a result, showers and thunderstorms are expected given enough instability and moisture. Best chance of this convection will be over the mountains, but the dynamics of this system would suggest potential for showers and thunderstorms over portions of the Central Valley as well. We`ll continue to monitor trends. Drier weather is projected toward the end of next week. Daytime highs will remain near or a few degrees below averages. && .AVIATION... VFR conds ovr Intr NorCal nxt 24 hrs exc isold tstms poss ovr Siernev til arnd 03z. Gusty wind poss near tstms with lcl gusts to 25 kts poss thru Delta. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Tucson AZ
320 PM MST Sat Sep 9 2017 .SYNOPSIS...Scattered showers and thunderstorms ending around midnight tonight. Expect only isolated mainly afternoon and evening showers and thunderstorms during the upcoming week. Warmer daytime temperatures Sunday with above normal high temperatures continuing Monday into Wednesday. && .DISCUSSION...Scattered showers with isolated thunderstorms were moving north-northeastward across southeast Arizona at this time. The strongest thunderstorms were across far western Pima County, with even stronger thunderstorms just south of the international border south of Organ Pipe National Monument. The 09/12Z Univ of AZ WRF-NAM and WRF-GFS as well as several HRRR solutions depict generally scattered coverage of showers/tstms into this evening. These solutions suggest that much of the Tucson metro area will remain dry into this evening. At any rate, the official forecast continues with isolated to scattered showers/tstms this evening, then a slight chance of showers/tstms mainly east of Tucson late tonight. Would not be surprised if precip-free conditions occur area- wide late tonight, particularly if the high resolution models are reality. High pressure aloft will be centered over southern Colorado Sunday morning with low pressure aloft centered west of the southern California coast near 31N/122W. The mid-level steering flow is progged to become more southeasterly Sunday versus the nearly sly mid-level flow this afternoon. This flow regime may actually favor showers/tstms to perhaps move into portions of the Tucson metro area Sunday afternoon and evening. At any rate, have continued with scattered showers/tstms across the White Mountains Sunday afternoon/ evening with isolated coverage elsewhere. A fairly low-grade pattern for showers/tstms then exists Monday into next Saturday. High pressure aloft is progged via the deterministic GFS/ECMWF/CMC to build over this forecast area Tuesday as the upper low moves northward toward the central California coast. The mid- level flow Wednesday is progged to become southwesterly as the upper moves eastward into central California, and high pressure aloft migrates south of the area. The bulk of deeper moisture Thursday should be shunted east of this forecast area as southwesterly mid-level strengthens in response to a tightening pressure gradient. However, enough moisture should exist to support isolated afternoon/evening showers/tstms Wednesday into Thursday east of Tucson with dry conditions elsewhere. Have opted for dry conditions across much of the area Friday into next Saturday as a low amplitude upper trough continues over the southwestern CONUS. Warmer daytime temperatures will occur Sunday into Monday followed by no significant change in daytime temperatures Tuesday into Wednesday. A modest cooling trend with high temperatures trending closer to seasonal normals will then prevail Thursday into Friday. && .AVIATION...Valid thru 11/00Z. Scattered -TSRA/-SHRA ending around midnight tonight. Isolated -TSRA/-SHRA returning Sunday afternoon. Otherwise, VFR conditions into Sunday afternoon. Surface wind variable in direction mainly less than 10 kts through tonight. Surface wind ely/sely 5-15 kts with gusts to 20 kts Sunday. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated to scattered thunderstorms into this evening followed by dry conditions across much of the area late tonight. Only isolated thunderstorms are forecast to occur during the upcoming week, mainly during the afternoon and evening hours. Expect elevated wind speeds from the southwest Thursday and Friday as a trough moves north of the area. Otherwise, 20-foot winds will generally be terrain driven less than 15 mph. && .TWC WATCHES/WARNINGS/ADVISORIES...None && $$ Francis Visit us on Facebook...Twitter...YouTube...and at
Area Forecast Discussion
National Weather Service Las Vegas NV
907 PM PDT Sat Sep 9 2017 .SYNOPSIS...Scattered thunderstorms with heavy rain will continue into early evening, especially in areas to the south of Las Vegas. Moisture will remain in place through early next week, with shower and thunderstorm coverage gradually decreasing each day. Moisture is likely to be pushed out of the region later this week as a transition to a drier, fall-like pattern begins. && .UPDATE...Low pressure well offshore of SoCal was taking the best forcing for thunderstorm development farther southwest than expected earlier. Storms over our area went to bed early this evening, and new model runs suggest much less activity Sunday than previous runs showed. Thus, cancelled the Flash Flood Watch early. Also reduced PoPs overnight tonight. && .PREV DISCUSSION... 225 PM PDT Sat Sep 9 2017 .SHORT TERM...Through Monday night. Thunderstorm coverage has increased over the past few hours across eastern San Bernardino and southern Mohave Counties. 1000-2000 J/kg surface based CAPE along with vorticity lobe lifting northeast driving the convection in that area. With impressive precipitable water values in place its making for a heavy rain storm environment. The question becomes just how far north storm will make it into Clark County. Confident northeast Clark and northern Mohave County will not see heavy rain so cancelled the Flash Flood Watch. Las Vegas may just be on the northern edge of storms so opted to keep the valley in the watch for now. The HRRR indicates convection should shutdown between 8-10 pm this evening. Closed low off the central California coast progged to drift south Sunday with best forcing shifting west across the San Gabriel and San Bernardino Mountains. On Monday, low begins to shift back north with broad area of diffluence for better coverage in showers/thunderstorms across southern Nevada. .LONG TERM...Tuesday through Saturday. Closed low will shift eastward onshore of the California coast on Tuesday. This will continue southerly flow over the area while shifting best moisture and forcing westward resulting in decreased activity levels. Best chances for showers and storms for these days will be across the higher elevations with more isolated activity in the lower elevations. The low will continue on its eastward track on Wednesday and Wednesday night passing across the local area late in the day. It will weaken in the process as it dissolves into the prevailing flow ahead of a more prominent trough entering the Pacific northwest Thursday and Friday. As the trough passes overhead on Wednesday rain chances will be limited to the southern Great Basin and northern Mohave County with mostly dry weather expected for Thursday and Friday as drier air filters in behind the exiting shortwave. As low approaches and passes across the area midweek breezy south to southwest winds of 15-20 mph gusting around 25 mph will be possible each day Tuesday through Thursday. Slightly higher winds will be likely across the western Mojave Desert. Temperatures will rise a couple degrees Monday to Tuesday before dropping back down below normal midweek behind exiting trough. .AVIATION...For McCarran...Winds will remain out of a northeast-east direction with speeds mostly 10 knots or less before trending from the west late evening. Winds will shift back to a northeast-east direction Sunday afternoon. Isolated showers or thunderstorms this evening with a slight chance of storms possible around the valley Sunday afternoon. For the rest of southern Nevada, northwest Arizona and southeast California...Scattered thunderstorms will continue across southern Mohave and eastern San Bernardino counties drifting northward into Clark, Inyo, Lincoln, and Nye counties through early evening. Winds will be forced by nearby convection but should otherwise follow diurnal trends. Gusty, erratic winds will be possible with any storms that move over the terminal in addition to heavy downpours, lowering CIGS, and lightning. .SPOTTER INFORMATION STATEMENT...Another day of showers and thunderstorms capable of producing gusty winds and flash flooding is expected. Spotter activation is requested for San Bernardino and Mohave Counties. Elsewhere, spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ Update...Morgan Short Term/Aviation...Pierce Long Term...Guillet For more forecast information...see us on our webpage: or follow us on Facebook and Twitter