Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/05/17

Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
557 PM MDT Mon Sep 4 2017 .AVIATION... 00Z TAF CYCLE Isol SH and TS will impact western and northern areas through at least the eve hrs. Gusts to near 40 kt will be the main concern through 03/04z. Then gust potential should lower some. FMN/GUP/SAF are likely candidates to receive impacts. LVS will be possible later in the eve but didn`t show it in the latest terminal forecast. Will update accordingly. Gusty east canyon wind expected at ABQ Tue morning with gusts near 35 kt. AWW is possible although not indicated in the latest fcst. 50 && .PREV DISCUSSION...300 PM MDT Mon Sep 4 2017... .SYNOPSIS... High pressure aloft will dominate northern and central New Mexico this week however the center of circulation will wobble around the Great Basin and southern Rockies, resulting in subtle day to day variations in areal coverage and movement of showers and storms. A cold front is still forecast to move into northeast and north central New Mexico later tonight, then advance south and westward to the Continental Divide Tuesday and Tuesday night on gusty northeast to east winds, which would focus showers and storms from the central mountain chain westward. Highs Tuesday will be 5 to nearly 20 degrees cooler central and east, and just a little cooler west. Thereafter, isolated to scattered showers and storms will be featured over mainly the northern and western high terrain. High temperatures over the east will rebound by Thursday and overall will be slightly above average to end the week. && .DISCUSSION... Little bigger crop of afternoon showers and storms compared to Sunday, but located mainly along and west of the Contdvd, with just a few along the central mt chain. Movement is to the south and southwest, although models suggest that will transition to more westerly this evening. This activity will tend to be a bit drier similar to Sunday with gusty winds and lightning and not so much rain, thanks in part to dew points having mixed out into the 30s again this afternoon over much of the central and west. The cold front is progged to make it`s entrance into ne NM late this evening or around midnight, but winds may shift to north prior if precipitation develops along the ne NM/se CO border earlier in the evening, per the HRRR and RAP13. An easterly wind will blow into the RGV Tuesday and continue Tuesday night courtesy of the front and mid level winds. Convection Tuesday and Tuesday night would be most likely over the western third to half of the forecast area, but the NAM12 and GFS generate very little over the region, in fact the GFS paints more over the north central and east. Consequently didn`t make wholesale changes to the pop grids for this period although Wednesday may be more active than Tuesday if the models are correct. There could be some potential for smoke observed over ern CO today to be transported by the front into ern NM but vent rates in the fair to good category over the east central and southeast Tuesday. Temperatures Tuesday over the central and east will be about 5 to nearly 20 degrees cooler than today`s, with only slight cooling in the west. Expect highs to rebound in the east by Thursday and overall to be near to above average for the rest of the week. Models still kicking around the idea of an incoming trough late this week, and developing a closed low to our west, which shifts the upper high center over or even southeast of NM. Given the wishy-washy nature, generic pops over the west and north still good for late this week. There could be another vigorous cold front early next week, but that depends on the variably forecast upper air pattern. && .FIRE WEATHER... After above normal temperatures today, a back door cold front will enter from the northeast tonight and push all the way to the continental divide by mid day Tuesday. High temperatures will fall a few to 10 degrees central and west on Tuesday, and up to 19 degrees across the east. Scattered to isolated showers and thunderstorms will favor central and western areas on Tuesday with the best precip chances in the northern mountains. Humidities will also climb a few to 20 degrees with the front, so wetting footprints will grow. With the broad upper high centered over the Great Basin, these storms will move southward and southwestward off the high terrain while lingering into Tuesday evening. Most of the area from the spine of the Sangre De Cristo Mountains eastward can expect poor ventilation on Tuesday. Haines Indices will decrease with the front and remain moderate for the remainder of the week. The high pressure system aloft will weaken and migrate southeastward over southern NM Wednesday and Thursday, before tracking further southeastward over extreme southeast NM and/or west TX over the weekend. Clockwise flow around the high pressure system will cause the track of showers and thunderstorms to shift more out of the south and west. After trending gradually drier during the latter half of the work week, humidities should be able to climb some this weekend. Daily rounds of scattered to isolated showers and thunderstorms will favor central and western areas Wednesday and Thursday, before focusing more exclusively on western and northern areas this weekend. Poor ventilation will cover much of the east on Wednesday while spreading to include the middle and upper Rio Grande Valley. vent rates will improve during the latter half of the work week, although some poors will linger across northeast areas into Thursday. && .ABQ WATCHES/WARNINGS/ADVISORIES... None. && $$ 50
Area Forecast Discussion
National Weather Service Denver/Boulder CO
936 PM MDT Mon Sep 4 2017 .UPDATE... Issued at 925 PM MDT Mon Sep 4 2017 Minimal cloudiness over the CWA at this time. No precipitation. Northeasterly low level winds continue over the plains and foothills. As far as updates go, I`m still not sure where the cloud deck at 700 mb is supposed to materialize from on the models later tonight. Left some clouds in, not not total coverage. No pops overnight. Temperatures are in pretty good shape. && .SHORT TERM...(This evening through Tuesday) Issued at 242 PM MDT Mon Sep 4 2017 Leading push of cold front has moved through Denver metro area, but little cooling with this one. Main front was now pushing through Greeley and Fort Collins, and will move through Denver and the rest of the plains late this afternoon. Surface observations show smoke is eroding from the northeast, so improvement will continue to occur behind the front through the evening. Latest HRRR Near-Surface Smoke represents this nicely so have largely adopted this field for smoke forecast tonight. While the plains largely scour out of the near surface smoke, we do anticipate the smoke plume aloft to keep hazy conditions in place on the plains, and some smoke in the high country. With regard to thunderstorms, frontal surge this afternoon should push any convection farther to the south and across the Palmer Divide. Any convection will only be isolated in coverage. Overnight, we should eventually see some high based stratus development. Maybe a couple sprinkles from that otherwise dry conditions will persist through Tuesday. Highs on Tuesday will be considerably cooler in post frontal airmass. Most of the plains should see highs closer to 70F. .LONG TERM...(Tuesday night through Monday) Issued at 242 PM MDT Mon Sep 4 2017 Tuesday night a large upper level ridge of high pressure will stretch from British Colombia south into northern Mexico...with a deep upper level trough of low pressure covering much of the central and eastern United States. Colorado is stuck between these two systems under the influence of a dry northwesterly flow aloft. The combination of the dry and cool airmass in the wake of Monday`s strong cold front and mostly clear skies will lead to cool temperatures across the plains Wednesday morning. Most locations across northeastern Colorado should see low temperatures in the 40s. A gradual warming trend is expected through the end of the work week as the upper ridge remains entrenched over the western half of the United States. By Friday...the upper ridge breaks down somewhat and shifts eastward over the Rocky Mountain Region. This is in response to an upper level trough of low pressure deepening along the west coast of the United States. This pattern should allow some subtropical moisture to flow into Colorado from the south and southwest...resulting in increasing precipitation chances...mainly across the high country. Models show moisture continuing to increase over the weekend which may result in better chances for afternoon and evening showers and storms across the plains and Palmer Divide. The GFS...ECMWF and GEM Models are are showing another cold front moving across northeastern Colorado on Monday which could result in another cool and cloudy day. Since this is all the way out in day 8...have decided only to lower high temperatures only a few degrees at this time. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 925 PM MDT Mon Sep 4 2017 Models keep the easterly component to the low level winds all night and Tuesday. No drainage winds! Models keep showing a pretty decent cloud deck to develop after 06Z. If that does occur, the deck will be above BKN060, but not much higher. We`ll see. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......RJK SHORT TERM...Barjenbruch LONG TERM....Kalina AVIATION.....RJK
Area Forecast Discussion
National Weather Service Columbia SC
1047 PM EDT Mon Sep 4 2017 .SYNOPSIS... Fair weather will continue tonight across our forecast area. Moisture will begin to increase ahead of an approaching cold front Tuesday. The front will be in the area Wednesday. There will be an increased chance of showers and thunderstorms especially Wednesday. It will be cooler and drier behind the front for Thursday into Saturday. Hurricane Irma will continue to be monitored into early next week. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Weak surface high pressure over the Southeast will slowly move offshore tonight. Atmospheric moisture will be slowly increasing with deeper southwesterly flow developing ahead of an approaching upper trough. Regional radar as of 0245Z showing weak shower activity over eastern Georgia which could potentially reach the southern CSRA before dissipating. A weak shortwave appears to be maintaining this activity, but moisture remains limited. Added a slight chance of rain showers to the southern CSRA based on current radar trends for the next hour or two. Overnight lows tonight will moderate a bit compared to the past couple of nights, ranging from the middle 60s north to around 70 south. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... A cold front will be approaching the region from the northwest through the day Tuesday, and expect moisture to be on the increase through the day in advance of the front. There will be a weak cap through the day, with weak to moderate instability possible. Scattered showers and thunderstorms should develop by the afternoon lasting into the evening hours over the area. The main cold front will not move into the cwa until late Tuesday night into Wednesday morning. The front will be slow to move through the cwa during the day Wednesday, which will bring an additional chance for showers and thunderstorms throughout the daytime hours. Rain chances should begin to diminish Wednesday night as the front finally pushes east towards the coast and drier air begins to move into the region from the west. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Dry conditions should occur with dry high pressure over the region Thursday through Saturday night. After that, an onshore flow pattern may return to the region late in the weekend, bringing increasing chances for rainfall into early next week. We will continue to monitor the intensity and forecast tracks for Hurricane Irma through the longer term periods for possible impacts on the region early next week. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Expect mainly VFR conditions during the TAF period but there may be areas of stratus and fog during the early morning hours and thunderstorms are possible in the afternoon. Moisture will be on the increase in the southerly flow between offshore high pressure and an approaching cold front. However, based on the initial dryness and weak moisture advection believe stratus and fog will be limited during the early morning hours. The GFS and NAM MOS plus SREF and HRRR indicate mainly VFR conditions. However, included a period of MVFR fog at AGS and OGB because of increased moisture and cooling at these river valley terminals. The chance was too low to include restrictions at the remaining terminals. The moisture is expected to remain somewhat shallow through Tuesday afternoon. Main frontal forcing should remain west of the area. Therefore, expect limited thunderstorm coverage with the chance too low to include in the terminal forecasts at this time. Wind will be light and variable tonight with an inversion and weak pressure gradient. The MAV and MET MOS support wind southwest near 10 knots during the day Tuesday. The NAM and GFS Bufkit suggest peak gusts about 15 knots. EXTENDED AVIATION OUTLOOK...Thunderstorms may become more widespread Tuesday night and especially Wednesday associated with a cold front moving into the area. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$
Area Forecast Discussion
National Weather Service State College PA
1046 PM EDT Mon Sep 4 2017 .SYNOPSIS... A cold front will move into the northwest part of the state tonight, then progress very slowly to the east during the day Tuesday. A deepening upper level trough will march east across the commonwealth Wednesday leading to cooler than normal temperatures and scattered showers. Hurricane Irma is around a week away from the U.S. mainland. && .NEAR TERM /UNTIL 7 AM TUESDAY MORNING/... Line of storms moving steadily across LE now, and some rain should reach Warren Co by 1030 PM. There is one very strong- looking bow echo over the water which, on it`s curent track, would strafe the PA-NY border, but stay mainly to the north of PA. It still bears watching, but the HRRR and RAP runs from the last several hours have been insistent on decreasing the coverage of the showers/storms as they move into C PA. The CAPE is definately lower over McKean Co than Warren Co. Deep-layer shear is still respectable, though. Have adjusted the POPs and timing slightly for the near term, and kept the idea of decreasing coverage and intensity. But, the SPC continues with a SLGT risk into Warren Co and MRGL risk a few Cos deeper into C PA. So, will continue on with the enhanced wording for tstms in the wx grid. But, the trend seems to be for weakening as the HRRR and RAP indicate. Prev... Quiet start to the evening with partly cloudy skies and seasonal temperatures. Band of showers and thunderstorms will approach NW zones later in the evening and weaken as the push SE into central PA. Before they weaken, across the NW zones, the strongest storms could have gusty winds and frequent lightning with them. && .SHORT TERM /7 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... The focus for thunderstorms on Tuesday will be along the slow moving frontal boundary which will shift to the Susq Valley. The best llvl SW winds and larger scale forcing will pass across the region mainly east of a KMDT to KELM line, thus limiting the chc for gusty winds and hail acrs the region near and to the south of a KTHV to KAVP line. The upper flow gradually backs from the west to the southwest on Wednesday helping to slow the cold front to a crawl with an area of anafrontal rain blossoming and moving NE across the southeast part of the region Tuesday night. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Cold front moves into the area later Tuesday and slows down as a longwave trough drops over the Great Lakes and becomes stationary. This will bring a period of wet weather Tue into Wed night with potential QPF amounts of 0.75-1.25. Clouds and rain showers will keep temps below normal during this period. Would expect most of the showers and storms to be out of the area Thursday, but still some chance of a shower across the north into Friday morning as the upper level trough finally swings across. Large high builds into the area for next weekend. Weather looks to be dry but temps will remain on the cool side. After that, heading into early next week, interaction between the departing high pressure area and Hurricane Irma will determine the track it will take as it approaches the U.S East Coast. Still quite a wide variation of solutions forecast by longer term guidance after it slides by the northern Bahamas, so stay tuned for now. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Cold front dropping across the Great Lakes will track across Pennsylvania later tonight and Tuesday. Ahead of the front, extending along the southern and eastern shore of Lake Erie at 02z, is a broken line of strong to severe thunderstorms. This line will impact the NW mtns over the next several hours, though it should weaken fiarly rapidly as it pushes further into the CWA. So, at 02z, MVFR cigs popping up along the higher terrain of the west as core of 40kt low level WW jet swings through. Remainder of region will remain VFR through much of the overnight. KBFD will see biggest tstm impacts from the line, while showers and possibly a weakening tstm will approach central mountain terminals after 06z. Toward sunrise, ceiling reductions encompass much of NW half of CWA. These spread into central and SE portions on Tue as numerous showers and scattered potentially strong thunderstorms impact those regions as the front stalls nearby. .Outlook... Wed...Reductions poss in SHRA - mainly NW mtns and east of Susq River. Thu/Fri...Widespread MVFR north. VFR elsewhere. Sct showers mainly north. Sat...No sig wx. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Ross NEAR TERM...Ross/Dangelo SHORT TERM...Ross/Lambert LONG TERM...Lambert/Gartner AVIATION...RXR
National Weather Service Eureka CA
316 PM PDT Mon Sep 4 2017 .SYNOPSIS...Temperatures will gradually cool over the next couple of days with highs falling back to near normal by Wednesday. Smoke should also begin to move to the north and northeast toward the middle of the week. Chances for showers and thunderstorms will return for Tuesday and Wednesday as a low pressure system moves into the region and taps into some tropical moisture. && .DISCUSSION...Short Term (Tonight through Thursday Night) Main issues for the CWA center around dreadful smoke conditions for both the coast and interior zones. Wildfire activity was strong again today especially the fires over Siskiyou County and Trinity County where large plumes were evident. Given the Southeast flow aloft all that smoke is being carried to the north coast and impacting Crescent City and all other coastal communities. Same of course can be said for all interior communities where smoke is trapped overnight. An Air Quality Alert (North Coast Air Quality Management District) is in effect for most of northwest CA and given the current and short term weather pattern expect that to continue for at least another 24-48 hours. The good news is that the pattern should see a significant change by Thursday so much of the smoke should be shunted off to the north and northeast. As far as the weather goes...the hot and dry conditions experienced over the weekend will give way to cooler temperatures as a low pressure system currently over the Pacific slowly migrates toward the North Coast. This system will bring bring much cooler daytime temperatures through Thursday but also a threat of more thunderstorms...and yes more lightning induced fires. At this time best chance for thunderstorm activity will be tomorrow and Wednesday affecting the usual places ..interior Humboldt County...Trinity County and easter Mendocino counties. But given the latest gfs 18z run the low/trough remains over the coast into Saturday maintaining slightly below normal temperatures and at least a continued threat of thunderstorms into the weekend...and perhaps much less smoke. Long Term (Friday through Monday) The broad upper level trough that absorbed the remnant energy of Tropical Storm Lidia will bring the chance for shower and thunderstorm activity across interior portions of Del Norte, Trinity, and extreme northeastern Mendocino counties on Friday. Convective parameters seem to be split as to whether or not thunderstorms will actually develop thus confidence isn`t high enough to place them in the forecast with this package. The chance for precipitation will come to an end late Friday night into early Saturday morning as an upper ridge noses its way into the area. Expect above normal temperatures and dry weather starting this weekend and into early next week. && .AVIATION...Smoke intrusion has had some impact on area airports/airfields in the last couple of days. This is due to numerous wildfires pumping smoke throughout the region. At the coast, fog development has been inhibited. Although clouds themselves have been clear, a smoke layer continued to measure "cigs" anywhere from 015-040 feet average. AS the inversion broke today, smoke was able to mix down and reduce visibilities into IFR at the coast. Also breezy winds developed along sections of the coast...especially EKA-ACV. Inland areas including UKI continued to experience smoke advection with the more concentrated amounts being in the Northern areas. Throughout the forecast period, no significants changes are expected except for an influx of mid-high cloudiness, the remnants of Hurricane Lidia. For the interior, possible flight hazard or two due to the threat of isolated thunderstorms in the next couple of days. && .MARINE...The buoys are flirting with Small Craft Advisory level winds this afternoon, but this is expected to be short lived as they will gradually be turning to the south. Directional spectrum plots show that the 4 or 5 feet at 15 seconds are from the south while locally driven wind waves slowly subside due to the change in wind direction. Overall, mariners and other ocean dwellers can look for light winds and seas to continue for the next couple of days with locally higher winds being possible around Cape Mendocino. && .FIRE WEATHER...As high pressure weakens and moves east...focus now changes from hot and dry to thunderstorm potential for Tuesday and Wednesday as a pacific low approaches from the west. A weak closed upper low circulation will slowly move northward up the coast entraining some mid and high level moisture into northwest CA. This feature will also destabilize the airmass as it weakens on Wednesday and moves across the coast and then northward into western Oregon. Best chances for thunderstorm activity looks to be Wednesday as the strongest vort lobe moves over the region while timing is ripe during afternoon heating. However can`t rule out Tuesday either given the favorable southeasterly flow and decent amounts of available moisture. Axis of instability on Tuesday appears to be over southern Trinity Co. and Yolla Bolly area then shifting slightly westward for Wednesday. Did also add a slight chance of showers/tstorms for tonight as well as total totals close to 53ish and HRRR showing some returns later this evening. Potential storms don`t look especially wet but not convinced there will be a ton of lighting either. For now will go with a headline for interior zones for isolated storms with limited rainfall. The good news is that by Thursday smoke transport should be toward the northeast so improving sky conditions may be on their way. tonkin && .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS...None. && $$ 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 Flagstaff AZ
903 PM MST Mon Sep 4 2017 .SYNOPSIS...Expect a slow increase in shower and thunderstorm activity for the remainder of the week, as high pressure weakens and southerly flow develops. High temperatures will decrease to near average over the next several days. && .DISCUSSION... A busy evening across northern Gila and southern Yavapai counties looks to be coming to an end. The potential for isolated showers will persist into the overnight hours. && .PREV DISCUSSION /318 PM MST/...Significantly more active day than yesterday in terms of convective development with isolated to scattered showers ongoing across a large portion of the area. The last few runs of the HRRR have been persistent in developing a cluster of storms over northern Gila and tracking this to the west across southern Yavapai County early to mid evening. Based on current radar trends, this seems like a plausible scenario. Shower and thunderstorm activity will diminish greatly from late evening onward. The remainder of the week will see a shift in the pattern with the ridge over the Great Basin weakening and shifting to the east. We will also see the development of low pressure off the southern California coast. This will lead to southerly flow and increasing moisture over the region. Therefore, expect increased shower and thunderstorm chances over the next several days. Along with the increased convective threat, temperatures will cool to more normal levels for early September. && .AVIATION...For the 06Z package...Predominantly VFR will persist across northern Arizona. Storm coverage will likely increase Tuesday afternoon from KFLG to KRQE southward. Stronger cells will produce moderate rain with potential for MVFR visibility and gusty winds up to 45 kts. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Moisture will gradually increase through the week leading to an increase in daily shower and thunderstorm activity. Daytime temperatures will trend down closer to early September averages. Outside of storms, winds will remain light with a slight increase in southerly wind by late in the week. && .FGZ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...KD/TPS AVIATION...KD FIRE WEATHER...KD/MCT For Northern Arizona weather information visit
Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
544 PM MDT Mon Sep 4 2017 .SHORT TERM...(Tonight through Tuesday night) Issued at 150 PM MDT Mon Sep 4 2017 Early this afternoon surface observations show the Canadian cool front draped near the WY/CO border and then southeast through eastern CO. There will continue to be a southward push into northwest CO and northeast UT this evening, but it appears with the main thrust of the digging upper level trough well east of the Rockies, the cool surface air will be too shallow to make it over the Tavaputs and Roan Cliffs. Although all mountain ridges have diurnal convection occurring this afternoon, the southern mountain areas are favored for greatest coverage of storms, with some drifting off over areas south of the San Juan mtns. Upper level high pressure stretched from eastern OR to NM will slowly ease its grip on the region Tuesday, but southern mountain areas will again have enough moisture for another round of afternoon and evening isolated/scattered storms. With the slightly lower heights and modest cooling aloft, Tuesday will be a few of degrees cooler than today. It looks like Tuesday night will bring the coldest temperatures of the week to the high valleys and Northwest Plateau of Colorado thanks to some cooler air filtering westward from the cool Canadian airmass plunging south east of the Divide Tuesday. We will continue to monitor these areas for the potential for frost, but at this time it appears temperatures will remain just warm enough to preclude a serious frost threat. Smoke/haze emanating from the wildfires over MT and the Pac NW states is readily seen in our GOES-16 preliminary/non-operational imagery behind the cool front. HRRR model smoke concentration forecasts show the higher concentrations of smoke moving south over especially northern CO and UT over the next 24 hours. While we have noticed hazy conditions the past few days, expect visibility to be noticeably reduced a little more through Tuesday and possibly beyond. .LONG TERM...(Wednesday through Monday) Issued at 150 PM MDT Mon Sep 4 2017 The northwest center of a double-barreled upper level high pressure ridge extending from the upper Great Basin to New Mexico will weaken and give way to the southeastern center near the Four Corners by Thursday. Until then, eastern UT and western CO will be under relatively stronger subsidence and drier air. That will not completely preclude afternoon convection from developing over mainly the San Juan region each day where available moisture will be slightly higher. By late Thursday, the axis of the ridge will either be directly overhead or just to the east. Either way, the upper level flow turns out of the south to southwest, and enhanced by a developing trough or closed low off the California coast. This will increase precipitable water values over much of the region to between 0.75 and a little over 1.00 inch. While these values are not alarming, it will increase chances and coverage of showers and thunderstorms for late Thursday thru Monday. With the weakening upper level high pressure and then increased cloud cover and moisture for the end of the week, expect high temperatures to lower further for the last half of the week. then level off for the weekend. However, temperatures will remain above normal through the period. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 544 PM MDT Mon Sep 4 2017 VFR conditions will prevail through this evening across the area. Isolated to scattered showers and thunderstorms, currently located south of I-70 and favoring the southern mountains and valleys, will continue through 03Z. Storms will be capable of producing gusty outflow winds to 35 kts. Hazy skies early this evening will turn smokey with reduced visibilities overnight into Tuesday as a cold front helps push this smoke further south and west across much of Colorado and eastern Utah. The northern and central areas of the state will have the best potential to see reduced visibilities in smoke. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...BM LONG TERM...BM AVIATION...TGJT
Area Forecast Discussion
National Weather Service Houston/Galveston TX
924 PM CDT Mon Sep 4 2017 .DISCUSSION... Surface high pressure was ridging into Southeast Texas this evening. Isolated showers were moving around the ridge over the offshore waters in the Gulf. Since sunset the showers have pretty much dissipated; although, a few still were forming about 60 nm offshore of Matagorda. The 01Z run of the HRRR shows the potential for isolated shower development off of the coast through the remainder of tonight. 40 && .PREV DISCUSSION... /ISSUED 630 PM CDT Mon Sep 4 2017/ AVIATION... Generally light south to southeast winds are expected for the remainder of the evening. Some patchy IFR to MVFR fog will likely set in again tonight/early tomorrow morning before dissipating after sunrise, very similar to what has been occuring the past few mornings. A stray shower or two may be possible along the seabreeze tomorrow afternoon. Otherwise, VFR conditions are expected throughout the taf period. 11 PREV DISCUSSION... /ISSUED 346 PM CDT Mon Sep 4 2017/ DISCUSSION... Moisture from a disorganized low in the Bay of Campeche is moving north into the upper Gulf Coast with isolated showers now being seen on radar approaching Matagorda. Rain chances will increase along the coast and nearshore waters through tomorrow morning as this moisture continues northward though convection should remain isolated to widely scattered. The main threat will be isolated cells producing gusty winds affecting marine interests. A cold front currently entering the Texas Panhandle will move south over the next 24 hours and enter our northern CWA around midnight tomorrow night. Lift along the front is forecast to weaken as the front moves south and so a solid line of convection in North Texas is expected to develop gaps as it enters southeast Texas. Showers with moderate rainfall rates will be moving at a decent pace so QPF amounts should generally be less than a quarter of an inch. A surface high building south behind the front will advect cooler and drier air with dewpoints dropping into the 50s and lows in the 60s Thursday morning. The high will remain in place and slowly weaken so a gradual warming trend is expected Friday into the weekend. Hennig MARINE... Light onshore winds and low seas will continue through Tuesday, before increasing and becoming offshore Wednesday morning as a cold front clears the upper Texas coast. Expect winds to increase into the 15-20 knot range behind the front with stronger gusts; these elevated winds will result in seas building into the 3-5 feet range nearshore and 4-6 feet range offshore. Caution or advisory flags will likely be needed at times Wednesday through Friday before conditions begin improving over the weekend. Huffman TROPICAL... An area of low pressure in the Bay of Campeche is currently being monitored for potential tropical cyclone development over the next 5 days. Regardless of development, Wednesday`s cold front appears to make enough southward progress to keep any potential system well south of Southeast Texas as it pushes the area of low pressure into Mexico. Hurricane Irma also continues to churn east of the Leeward Islands this afternoon and is forecast to intensify further as it moves west to west-northwest towards Florida over the next several days. Hurricane Irma`s track beyond that point becomes a little less certain, but medium range deterministic guidance is in fairly good agreement that Irma is lifted northward before entering the Gulf of Mexico as an upper trough reaches the East Coast. Changes in the depth or trajectory of this trough would influence the ultimate track of Irma. Additional radiosonde observations will be taken across a few CONUS sites over the next few days to diagnose the upper air pattern better. As this data is incorporated to later model guidance, expect confidence in Irma`s forecast to increase. Regardless, impacts are not expected in Southeast Texas from Irma at this time but Irma`s forecast should still continue to be monitored over the next few days. Huffman && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 72 93 69 84 61 / 0 20 40 20 0 Houston (IAH) 73 92 70 86 63 / 10 20 40 30 0 Galveston (GLS) 80 88 77 87 73 / 20 30 30 40 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ Discussion...40 Aviation/Marine...11
519 PM PDT Mon Sep 4 2017 .SYNOPSIS... Expect low clouds to deepen to coastal slopes by this evening and a slight chance of thunderstorms over the mountains and interior locations will be possible. High temperatures will be much cooler than the past several days, but still a bit above average through this week. Night through morning low clouds and patchy fog are forecast through much of this week. && .SHORT TERM...(TDY-THU) Widespread cooling was occurring today across the forecast area. Most areas were down over 20 degrees compared to this time yesterday. Although high humidity continues to make it feel pretty sticky out there, some relief from the high temperatures is a welcome relief. The center core of Post Tropical Depression Lidia was located around 400 NM miles W of Los Angeles around noon today. Most of the shower activity is now located over the coastal waters. The last of the lighter showers have exited SLO county. Latest GOES 16 Vis imagery indicated plenty of cloud coverage across coastal areas with cloud streets visible over LA County due to fairly strong SE flow aloft. There is enough low level moisture that stratus was already starting to kick in across the LA Coast and San Gabriel Valley. Expecting low clouds to continue to deepen into this evening. Looking at the latest high res RAP and NAM soundings over the area, they were showing a fairly unstable atmosphere across the LA/VTU Mtns and southern portion of the SBA County Mtns this afternoon, but less there is much less in the way of available moisture between 600 to 700 MB. Convective parameters such as CAPE were around 1440 j/kg and LIs were around -7. PW values also still relatively high around 1.5" this afternoon based on GOES Sounder Imagery. Although high res models were not picking up on any precip across the region today, it`s hard not to discount at least a slight chance for all interior areas today from LA to SLO counties later this afternoon. If storms do initiate, they will be fast moving from SE to NW which should keep most convective activity over the mountains and interior areas such as Cuyama Valley and SLO interior valleys. Not anticipating any widespread thunderstorms like yesterday, but if storms do develop, there could be some training of thunderstorms and some localized flooding or flash flooding can`t be ruled out. For tonight, there will be plenty of low lingering moisture across coast and valleys. NAM-WRF cross sections were indicating the moist layer or marine layer to be around 3000 ft tonight into Tue morning. Have increased low cloud coverage to all areas W of the coastal slopes. Patchy drizzle is a possibility along the Central Coast and the San Gabriel Foothill communities of La Canada and La Crescenta late tonight into Tue morning. High temps for Tue will continue to trend lower with best cooling across coastal areas anywhere from 3 to 7 degrees cooler. Otherwise most inland areas will be about the same as today within a couple degrees. There will be some afternoon cu buildups over the LA/VTU County Mtns but for now, not anticipating any thunderstorms to develop as soundings were more stable and lack of mid level moisture. Wednesday should see a few degrees of warming as thickness and boundary layer temps trend up slightly. the marine layer should shrink down as well by Wed morning but still affecting coastal valleys. High Temps should around normal to a few degrees above normal for inland areas. .LONG TERM...(FRI-MON) Both the EC and GFS continue stay in agreement with large scale features through the extended period. AN upper trough out the PAC NW will begin to drop south in between a 592 DM high to the SW of SoCal and a 591 DM High centered over N. Mexico and extending west towards AZ and NV. The upper trough will deepen further over much of California by Thursday night and Fri. H5 and thickness lvls do lower a bit and there should be a few degrees of cooling and the marine layer should deepen both Fri and Sat. Best cooling will be for areas N of Point Conception. as the upper low cuts off just off the Central Coast. High temps should be around normal for this time of year, and night through morning low clouds are expected to continue through next weekend. Risk for mountain thunderstorms seems limited late this week. && .AVIATION...05/0015Z. At 00Z, the marine layer depth was around 2600 feet deep at KLAX. The top of the weak inversion was up to around 3300 feet with a temperature near 21 degrees Celsius. Low confidence in the current forecast. MVFR conditions should spread into most terminals through 05Z, possibly lowering to IFR north of Point Conception between 07Z and 16Z. KLAX AND KBUR...MVFR conditions will likely linger throughout tonight and into Tuesday morning. There is a 30 percent chance that VFR conditions could redevelop later tonight. Otherwise, stratus could scatter out +/- two hours than the current forecast. && .MARINE...04/900 AM. Former Tropical Storm Lidia will bring a chance of showers and thunderstorms to the coastal waters today. Winds and seas will remain below Small Craft Advisory criteria through Wednesday afternoon. However erratic and strong gusty winds... lightning... and choppy seas are likely near any showers or thunderstorms. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && .HAZARD POTENTIAL OUTLOOK...(THU-MON) No significant hazards expected. && $$ PUBLIC...Kaplan AVIATION...Hall MARINE...Sweet SYNOPSIS...B
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
929 PM CDT Mon Sep 4 2017 .UPDATE... Issued at 926 PM CDT Mon Sep 4 2017 Scattered thunderstorms will continue to move southeast across the southern part of the CWA through the late evening hours. These storms are occurring ahead of cold front that has now reached a KSLO-KCPS-KVIH line. This front will move south of the CWA by midnight. There are still some post frontal showers and thunderstorms, but still expect most of the rain to move south of the CWA by late tonight. Cooler air is moving in behind the front, and lows still look like they will fall into the upper 50s and low 60s. Britt && .SHORT TERM... (Through Late Tuesday Afternoon) Issued at 330 PM CDT Mon Sep 4 2017 Cold front currently extends from northern Illinois into west central Missouri. The RAP shows it moving through the CWA by late this evening. Latest GOES-16 imagery is showing an enhanced CU field developing ahead of the front from central Illinois into central Missouri. This is in the same area where the latest SPC mesoanalysis shows MLCAPES between 2000-3000+ J/kg. Would expect thunderstorms to develop in the next 1-2 hours as mid level ascent increases slightly on the tail end of a mid level trough that will move through the Great Lakes. Still expect that there will be a threat for a few severe thunderstorms given that deep layer shear will increase into the 30-40kt range this evening. Main threat should be damaging winds given the inverted-V profiles seen on the RAP soundings, but large hail will also be possible. Showers and thunderstorms will linger over southeast Missouri behind the front mid-late evening before finally ending by midnight. Expect a dry day on Tuesday as the front moves well south of the area, and the atmosphere becomes dry through a deep layer. Winds will become gusty as forecast soundings showing mixing up to 750mb. Highs will still be below normal despite the deep mixing. Britt .LONG TERM... (Tuesday Night through Next Monday) Issued at 330 PM CDT Mon Sep 4 2017 Period of well below normal temperatures with dry, tranquil conditions is expected through early next week. Main focus will be on temperatures, particularly at night. Coolest conditions still appear to be on Tuesday and Wednesday night before some slight modification in the airmass takes place. Continued to lean aob coolest guidance, and may still not be cold enough especially in favored valleys of east-central and southeastern Missouri. Lows in these locations may dip into the upper 30s on Wednesday night. While lows will be unseasonably cool for early September, it does not look like any records will be broken, though readings both Wednesday and Thursday morning at KUIN may get with a couple of degrees. Some moderation in the well below normal temperatures appears probable by early this weekend, but models diverge with respect to a backdoor cold front across the mid-Mississippi Valley. The ECMWF drops this front through the area whereas the GFS does not. Consequently, the ECMWF is several degrees cooler compared to the GFS. Regardless, at least slightly below normal temperatures along with a continued run of dry weather looks like to continue through this upcoming weekend and into early next week. Gosselin && .AVIATION... (For the 18z TAFs through 18z Tuesday Afternoon) Issued at 1217 PM CDT Mon Sep 4 2017 Thunderstorms will develop along a cold front that will move southeast across the forecast area late this afternoon and this evening. Thunderstorms will affect the St. Louis area terminals and KCOU between 23-03Z and could cause MVFR/possible IFR conditions along with gusty winds. There will be a shift in winds from southwest to north behind the front. There could be some lingering showers behind the front through mid evening before dry and VFR conditions are expected the rest of forecast period. SPECIFICS FOR KSTL: Thunderstorms will be possible ahead of a cold front at the terminals between 00-02Z. Any thunderstorms could cause MVFR/possible IFR conditions along with gusty winds. There could be some lingering showers behind the front through mid evening before dry and VFR conditions are expected the rest of forecast period. There will be some additional gusty northwest winds on Tuesday afternoon. Britt && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Omaha/Valley NE
633 PM CDT Mon Sep 4 2017 .SHORT TERM...(Tonight through Thursday) Issued at 201 PM CDT Mon Sep 4 2017 Much cooler temperatures are heading our direction as a longwave trough deepens from the Hudson Bay into the Mississippi River valley region. This leaves our region under strong north/northwesterly flow as a strong ridge of high pressure over the western states continues to build north into Canada. This will allow continued cool advection through the next couple of days. As was noted today, smoke from fires across the northwestern states will continue to create hazy skies as smoke should remain aloft. HRRR vertically integrated smoke field does take a good portion of the smoke to our south through the overnight hours. Brisk northerly winds are also expected the next couple of days, as high pressure pushes out of the Dakotas. Strong downward momentum should push gusts into the 30mph range, especially Tuesday. Cool advection will continue into Wednesday with surface high pressure moving overhead by Wednesday afternoon. High temperatures both Tuesday and Wednesday should be in the low 70s with lows in the 40s across the entire CWA. .LONG TERM...(Thursday night through Monday) Issued at 201 PM CDT Mon Sep 4 2017 Warmer return flow will move into the Central Plains by Friday while a weak shortwave trough moves southeast through deamplifying northwest flow aloft. We do have a small chance of showers and thunderstorms in warm air advection regime Friday night into Saturday. Weak ridging will move overhead into the weekend which should push temperatures back into the 80s. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 629 PM CDT Mon Sep 4 2017 VFR conditions through the TAF period. Hazy conditions with smoke and some mid and high level cloudiness this evening. HRRR vertically integrated smoke forecasts push this to the south of the TAF sites by around 08z. North winds 7-12kts to decrease to around 6kts early in the TAF period...then increase again above 12kts 14-16Z and above 15kts and gusty 15-19Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ SHORT TERM...Kern LONG TERM...Kern AVIATION...Zapotocny
Area Forecast Discussion
National Weather Service Norman OK
654 PM CDT Mon Sep 4 2017 .AVIATION... TAFS 0500/0524... A cold front, which extends from just north of Enid to near Woodward, will move southward this evening and overnight. A breezy north and northeast wind can be expected behind the front. Otherwise, VFR conditions will prevail. && .PREV DISCUSSION... /issued 247 PM CDT Mon Sep 4 2017/ DISCUSSION... The main forecast challenges are determining rain chances late tonight into Tuesday as well as dealing with near record cool temperatures Wednesday morning and Thursday morning. As of 230 pm today, Freedom (101) and Buffalo (100) have reached the century mark temperature wise according to the Oklahoma Mesonet. Additional locations in northern Oklahoma will likely exceed 100 degrees as well. Tonight, a rather strong cold front will move south and through at least the northern two thirds of Oklahoma. Sufficient capping will limit rain/storm potential. Kept 20% for storms after midnight in far northern Oklahoma, north of a Buffalo to Enid to Stillwater line where some of the latest models including HRRR depicted isolated storm activity. If storms form in these locations, they could be strong with hail and gusty winds due to sufficient MUCAPE 1500-2000 J/kg as well as 20-35 kt 0-6 km bulk shear. North to northeast surface winds will increase behind the frontal passage and should keep overnight lows higher than previous nights. On Tuesday, cooler and breezy/windy conditions can be expected. Rain chances remain uncertain due to the lack of significant moisture. However, there appears to be enough of a QPF signal from latest models, sufficient mid level moisture 600-800 mb, some mid level isentropic lift, and MUCAPE 100-1200 J/kg to allow for isolated showers and thunderstorm development across much of Oklahoma and north Texas through the day. Thus, kept 20% chance across the area. Any rainfall would be brief and light. Not many locations should get wet. Severe potential remains very low, though gusty winds could occur with any shower/storm. Surface wind gusts 30-40 mph will be possible across western Oklahoma and western north Texas during the daytime hours. Tuesday night into Wednesday morning, clearing conditions and decreasing surface winds will allow for cool night. Generally, went near the cool side of guidance lows, mainly in the 50s. Some locations, especially rural ones in northern Oklahoma, will likely fall into the 40s. Readings Wednesday morning will be near record lows in some areas. Wednesday, sunny conditions with very low humidity and light surface winds are forecast. Highs will generally be 5-10F below average. Wednesday night into Thursday morning, additional near record low temperatures will be possible as light surface winds and clear skies will allow for excellent radiational cooling. The coolest readings likely in the 40s may be over rural areas across the eastern half of Oklahoma closer to the surface ridge axis. Thursday through Monday, a slow warming trend can be expected along with generally dry conditions. Some latest models have been hinting at light QPF/rainfall mainly during the nighttime and early morning hours across western Oklahoma due to possible isentropic lift in northwest mid/upper flow. As a result, added low rain chances to account for this. Any rainfall will likely remain rather light and spotty. Temperatures may rebound to near average levels by next weekend. MBS CLIMATE... Record low temperatures Wednesday morning and Thursday morning may be in jeopardy across parts of Oklahoma and north Texas. Here are the records for Oklahoma City and Wichita Falls. Wednesday September 6 Oklahoma City...51 degrees...set in 1974 Wichita Falls...52 degrees...set in 1968 Thursday September 7 Oklahoma City...49 degrees...set in 1898 Wichita Falls...52 degrees...set in 1974 && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 69 81 52 80 / 0 20 10 0 Hobart OK 69 83 53 82 / 0 20 10 0 Wichita Falls TX 71 88 61 83 / 0 20 10 0 Gage OK 65 77 46 81 / 10 20 10 0 Ponca City OK 67 78 47 79 / 20 20 10 0 Durant OK 71 87 62 81 / 0 20 20 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$
Area Forecast Discussion
National Weather Service Paducah KY
636 PM CDT Mon Sep 4 2017 .UPDATE... Issued at 636 PM CDT Mon Sep 4 2017 The AVIATION section has been updated for the 00Z TAF issuance. && .SHORT TERM...(Tonight through Wednesday night) Issued at 250 PM CDT Mon Sep 4 2017 A fairly strong cold front will move toward the area this evening and then cross the region overnight. Scattered thunderstorms will accompany the front with much cooler air to follow as we head through the short term period. There remains a slight risk of severe thunderstorms for tonight, mainly along and north of the I-64 corridor. There is some offset of upper level wind dynamics and the surface cold front (better dynamics lag frontal convergence and instability) and we will be losing a good chunk of instability between 9 PM and midnight. Best guess for timing remains an onset of thunderstorms this evening with a 7-10 pm start time looking reasonable for the I-64 corridor of our region then progressing southward through the late evening and overnight. By tomorrow morning, showers/thunderstorms will be limited to mainly the quarter of the forecast area, ending across all of the region during the afternoon. A large 500 mb trough will pivot SE across the FA through mid week with surface high pressure building south into our region from Canada. The much advertised unseasonable cool pattern ushered in by northerly winds will ensue with max temps only in the mid to upper 70s Tuesday and the lower 70s on Wednesday with lows likely reaching the upper 40s in many locations Wednesday night. .LONG TERM...(Thursday through Monday) Issued at 250 PM CDT Mon Sep 4 2017 High forecast confidence still remains in place for a dry period from this Thursday through next Monday across the WFO PAH forecast area. Below normal temperatures (10-15 degrees) below normal are expected through the extended period. Regionally blended model guidance continues to be on the warmer end of the forecast temperature solutions. Again, weighted temperatures toward the EKD MOS, as well as the ECMWF/NAM-WRF guidance suite. temperatures. Given the drier air mass, diurnal temperature ranges will likely be within a 20 to 28 degree range. No precipitation expected through extended period. Although the ECMWF has been running about 5-10 decameters too low in 500 mb heights recently, it still remain much closer in height fields versus most of the numerical guidance suite. The ECMWF along with the RAP model guidance were the closest to the raw upper air observations at 12z and 18z Monday. Only the UKMET (which has historically been the case) is more accurate with height fields and low/high pressure centers in a global sense. Sensitivity of model fields at 500 mb versus observations is a good benchmark for model reliability. Will be interested to see how collaborated NHC/WPC forecasts handle Irma`s track later this week. There still remains some varied solutions from the Canadian, GFS, and ECMWF for the next several days. Depending on the final track of Irma, could see some interaction with the synoptic scale features near the WFO PAH forecast area around the middle of September. && .AVIATION... Issued at 636 PM CDT Mon Sep 4 2017 A broken line of thunderstorms has developed along the cold front from just north of KSTL to near KDEC in central Illinois. There is a strong signal in the latest short term guidance that a portion of this will be progressive, pushing eastward through KEVV and KOWB after 04Z, while the western portions will develop more slowly southward for awhile this evening and then mostly dissipate around 06Z. Left the VCSH at all sites except KPAH where it may remain dry. An outflow or enhanced frontal passage can be expected at KEVV and KOWB 04Z-07Z. VFR conditions are forecast, but lower conditions can be expected if a bonafide thunderstorm reaches any of the sites tonight. A few northwesterly gusts into the teens will be possible throughout the area Tuesday. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None. IN...None. KY...None. && $$ UPDATE...DRS SHORT TERM...GM LONG TERM...Smith AVIATION...DRS
Area Forecast Discussion
National Weather Service Tucson AZ
200 PM MST Mon Sep 4 2017 .SYNOPSIS...We`ll have enough moisture around this week for isolated to scattered afternoon and evening thunderstorms. Temperatures will run several degrees above average the first half of the week. && .DISCUSSION...Scattered showers and thunderstorms were occurring across portions of the White Mountains northeast of Safford at this time. Otherwise, mostly clear skies to partly cloudy skies prevailed across southeast Arizona early this afternoon. The cumuloform clouds were most prevalent near the mountains as well as south-to-southeast of Tucson. The high resolution models (i.e. 04/12Z Univ of AZ WRF-NAM and WRF- GFS as well as several HRRR solutions) were in general agreement with depicting scattered showers/tstms to continue to develop across portions of the area during the next few hours. These models generally agree that the favored areas for showers/tstms appear to be north of Tucson and south of Tucson, with showers/tstms to move westward into the western deserts this evening before dissipating by midnight. The disagreements amongst these solutions are for the Tucson metro area. The WRF-NAM and WRF-GFS were quite similar with depicting at least some showers/tstms to occur in vicinity of the metro area, and especially the northern portion (e.g. Catalina Mountains, Oro Valley, etc.) of the area. However, a few recent HRRR solutions have trended downward on precip potential for the Tucson metro area versus earlier HRRR solutions. At any rate, have made only very minor adjustment to the inherited gridded data PoPs based on these differing solutions. Thus, the offical forecast continues with isolated to scattered showers/tstms generally west of a Hannagan Meadow-Mt. Graham-Sierra Vista line. Gusty outflows may produce patchy blowing dust restricting visibility to less than one mile late this afternoon and early evening. The expectation is for showers/tstms to end by midnight. A similar forecast scenario is on tap Tuesday afternoon/evening. However, the Univ of AZ WRF-NAM and WRF-GFS suggests less coverage of showers/tstms may occur Tuesday afternoon/evening, as these solutions depict measurable rainfall to be west of Tucson. The official forecast continues with isolated showers/tstms across much of the area Wednesday afternoon/evening. Strong high pressure aloft presently centered over Utah is progged to become centered over southeast New Mexico/far west Texas area on Thursday. Meanwhile, a trough of low pressure will encroach upon the West Coast. The 04/12Z GFS/ECMWF/CMC and ensembles then depict an upper low to become centered near the central California coast Saturday as high pressure aloft remains over far west Texas. The southerly mid-level flow regime appears to be increasingly favorable for more widespread coverage of showers/tstms. The official forecast has isolated coverage of showers/tstms Thursday afternoon/evening and again Saturday. Somewhat greater coverage of showers/tstms appears to favor Friday afternoon/evening, at least based on these solutions. Although the upper low remains quasi-stationary just west of Los Angeles next Sunday and Monday, high pressure aloft is progged to build over this forecast area. Thus, have limited afternoon and evening showers/tstms to mainly near mountains northeast of Tucson to the White Mountains next Sunday and Monday with dry conditions elsewhere. High temperatures at least through Wednesday, and perhaps into Thursday, will average at least a few degrees above normal. Daytime temperatures Friday into Sunday will trend quite close to seasonal normals. && .AVIATION...Valid thru 06/00Z. Scattered -TSRA/-SHRA mainly west of a KSAD-KFHU line into this evening and Tuesday afternoon. Otherwise, VFR conditions into Tuesday afternoon. Surface wind variable in direction mainly less than 12 kts except gusts to 40 kts near stronger TSRA. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated to scattered afternoon and evening thunderstorms into Saturday, then isolated thunderstorms mainly near the mountains northeast of Tucson to the White Mountains Sunday and next Monday. 20-foot winds Tuesday through Friday will generally be from the east to southeast at 5-15 mph with occasional gusts to 25 mph. Expect terrain driven surface winds next weekend. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ Francis Visit us on Facebook...Twitter...YouTube...and at
Area Forecast Discussion
National Weather Service Las Vegas NV
327 PM PDT Mon Sep 4 2017 .SYNOPSIS...Isolated to scattered showers and thunderstorms are expected again this afternoon. The focus of the activity will be concentrated in Mohave and northern Lincoln counties as well as along the higher terrain. A ridge of high pressure will move over the area today and tomorrow increasing temperatures before an upper-level low digs into the western CONUS later this week. Moisture will remain trapped under the ridge keeping slight chances across most of the region each afternoon, primarily over the higher terrain. && .SHORT TERM...Today through Wednesday. Early morning cloud cover fizzled quickly this morning across much of the region as the moisture began to mix out. Though, fairly low- grade low-level moisture remains across most of our CWA this afternoon, with the 50 dewpoint line stretching from the Colorado River Valley-Lincoln County. With sufficient moisture and instability across the southern Great Basin and Mohave County today, thunderstorms are likely to continue through the afternoon and evening for these areas. The convective allowing models and the experimental HRRR are continually depicting a thunderstorm complex developing later this afternoon across central Mohave County. Notably, the RAP does have sufficient shear within Mohave county to generate a severe thunderstorm or two...Though, the major concern today continues to be outflow winds. With rather large DCAPE values and an inverted V profile from this mornings sounding, any storm could produce strong and gusty outflow winds. By Tuesday, as the high pressure elongates over much of the western CONUS, the southeasterly flow shifts further south limiting the bulk of the moisture to the southeastern CWA. Though, with sufficient low level moisture across most of the region, slight chances for showers and thunderstorms exists mainly along the higher terrain and in southern Mohave county. By Wednesday, a moist airmass ahead of the upper low will increase chances for showers and thunderstorms in the afternoon across much of the CWA. Temperatures will be above normal today and tomorrow before they approach seasonal normals on Wednesday with that northwestern airmass cooling temperatures a bit. .LONG TERM...Thursday through Monday. A general southerly flow will keep varying amounts of moisture over our region to fuel isolated to scattered thunderstorms through the coming weekend and early next week. The medium range models indicate a mean trough along the west coast and a broad ridge near the Four Corners Region will generally hold their positions. The hybrid remnant circulation of what was once Lidia is forecast to lift inland across northern California and Oregon Thursday ahead of a shortwave trough swinging down to take its place near the central California Coast which eventually becomes a closed circulation that remains nearly stationary Saturday through Monday. The GFS and ECMWF solutions are fairly close at depicting this though the ECMWF has a more well defined circulation which would enhance southerly flow and moisture advection over our area. This pattern will keep at least a slight chance of thunderstorm development over most zones along with temperatures trending downward toward normal. && .AVIATION...For McCarran...Typical diurnal winds are expected through Tuesday. However, isolated thunderstorms will occur mainly east of the area this afternoon and evening, leading to a slight possibility of thunderstorm outflow winds producing erratic conditions for the terminal area this evening, but confidence is too low to mention in the TAF. Any storm activity should die off later this evening but will develop again Tuesday afternoon which could result in thunderstorm outflow winds impacting the terminal. Clouds in the terminal area should remain above 12 kft. For the rest of southern Nevada, northwest Arizona and southeast California...Thunderstorms are possibly through this evening mainly over Mohave and Lincoln Counties and the Sierra. A little more thunderstorm coverage is possible Tuesday mainly over higher terrain. Prevailing winds through Tuesday will mainly follow typical diurnal trends but could be gusty and erratic near any storms this afternoon and evening. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM...Kryston LONG TERM...Adair AVIATION...Harrison For more forecast information...see us on our webpage: or follow us on Facebook and Twitter