Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/04/21

Area Forecast Discussion
National Weather Service La Crosse WI
1046 PM CDT Sat Jul 3 2021 .SHORT TERM...(This evening through Sunday) Issued at 149 PM CDT Sat Jul 3 2021 Latest water vapor satellite imagery indicates upper level ridge centered over Minnesota/western Wisconsin and shortwave trough over the Northern Plains. The upper level ridge has allowed for mostly sunny but smoky skies and light winds across the area per the latest visible satellite imagery/metars. Upper level/surface ridge will allow for dry weather tonight across the forecast area. Then...shortwave trough over the Northern Plains will flatten upper level ridge and west to northwest flow aloft develops across the northern tier states Sunday. This first shortwave energy weakens as it tracks southeast into eastern Minnesota and western Wisconsin Sunday. However...there are hints the shortwave energy has enough lift and moisture convergence to produce an isolated shower/storm across parts of the forecast area Sunday afternoon. Though...atmosphere over forecast area is capped and the chance for any shower/storm are very slim. At this time have kept forecast area dry for Sunday. The 03.00z NAEFS show around 1 degree standard anomaly and the 03.12z deterministic models suggest 925mb temperatures warming to around plus 25 degrees celsius Sunday. High temperatures are expected to be above normal with temperatures climbing into the middle 80s to middle 90s in some locations. .LONG TERM...(Sunday night through Saturday) Issued at 149 PM CDT Sat Jul 3 2021 A weak shortwave trough and accompanying cold front will drop into the area from the northwest late Sunday night into Monday. The axis of greatest instability will initially lie just off to our west ahead of the front Sunday evening. However, with time the developing, broadening low level jet will fan moisture transport out overhead Sunday night, bringing a quick increase in MUCAPE (~2500 to 3000 J/kg per RAP and NAM). But weakening low level frontogenesis along the front looks to be a limiting factor, with rain chances generally diminishing as the front progresses southeast overnight. The good news for Sunday evening fireworks displays is that shower/storm chances look to generally hold off until after midnight for majority of the forecast area. Main area of concern for rain potentially arriving before midnight would be Taylor and Clark counties, perhaps also from Wabasha to Jackson counties. The boundary will stall out near I-90 on Monday with a ribbon of higher PWATs (up to ~1.7") lingering over our southern/eastern counties despite better moisture transport shifting east. Once morning clouds depart, expecting plenty of sun with highs pushing mid 80s to lower 90s. Abundant instability as a result with 2000- 3000 J/kg MLCAPES, but nil deep layer shear and rather weak forcing. Still, a decent setup for potentially a few stronger storms with locally heavy rainfall at least for southern half of our area, contingent on how the morning evolves. Will continue to monitor. Tuesday looks to bring the greatest chance for any widespread rain to the area with the front still somewhere over our forecast area and a shortwave and surface low progged to move overhead from afternoon-Tuesday night. Potential for PWATs approaching 2" in spots, so will have to monitor heavy rain potential. High pressure and a cooler, drier airmass then build in behind this departing system Wednesday into Thursday, which looks to provide a period of mainly dry weather. Potentially another system in the Friday- Saturday timeframe, but predictability and confidence are very low that far out in the forecast. Increasing return flow does look to nudge temperatures back to near seasonal normals by late week. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1041 PM CDT Sat Jul 3 2021 VFR conditions are forecast for the TAF period with light southwest winds tonight increasing during the morning, gusting to 20 to 25 kts during the afternoon. Surface winds decrease in the evening, but LLWS quickly develops at LSE in the evening and possibly RST later in the night. Isolated showers and storms may approach from the northwest after 03Z, with the better threat for scattered storms coming after 06Z. The threat for an isolated thunderstorm looks to linger through the day on Monday. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...DTJ LONG TERM...Kurz AVIATION...Skow
Area Forecast Discussion
National Weather Service Bismarck ND
946 PM CDT Sat Jul 3 2021 .UPDATE... Issued at 946 PM CDT Sat Jul 3 2021 Thunderstorms have all but ended across western and central North Dakota. The 00Z CAMS continue to suggest an isolated shower or thunderstorm remains possible through about 06Z in the central part of the state, so kept a slight chance pop going to cover that potential. The more organized convective threat should be to our east, closer to the H85 jet and low level warm air advection, which will gradually push farther away (east) tonight. UPDATE Issued at 711 PM CDT Sat Jul 3 2021 Overall the current forecast is on track with only minor adjustments made to pops to better reflect the ongoing convection. Hi-Res models still suggest the best potential for convection will be in the eastern part of the forecast area, and this lines up fairly well with the ongoing convection. A few storms have managed to pulse up, but then weaken in an environment characterized by MLCAPE of 1500-2500 j/kg and relatively weak deep layer shear. UPDATE Issued at 415 PM CDT Sat Jul 3 2021 Ran a quick update to better align pops with current radar trends. A few thunderstorms have developed across southwest North Dakota with a few echoes now also showing up across parts of Sioux County. The latest Hi-Res models continue to have varying solutions in regards to convective development this evening, but the HRRR lends support for more storms generally in south central parts of the state towards the James River Valley. The potential for a strong to severe storm still looks on track with the latest mesoanalysis showing an environment of MLCAPE values in the 1500-2500 j/kg range, though shear remains fairly weak at 20 to 30 kts. && .SHORT TERM...(This afternoon through Sunday) Issued at 244 PM CDT Sat Jul 3 2021 Hot temperatures and thunderstorm potential this afternoon and evening highlight the short term forecast period. At the mid to upper levels, a compact shortwave/trough was located over central North Dakota and continues to move east. A remnant MCV also continue to rotate towards the Devil`s Lake Basin. This feature along with any remnant outflow from morning storms will serve as focus for more thunderstorm development this afternoon and into this evening. The best chance for some strong to severe storms will generally be from the eastern Turtle Mountains and south into the James River Valley. Here, plenty of buoyancy will be available with MLCAPE values ranging from 1500 to 2500 J/kg, however shear will be fairly weak in the 20 to 30 knot range. This will support the potential for some strong to severe storms capable of producing large hail up to the size of quarters and wind gusts to 60 mph. A conditional weak tornado/landspout threat may also exist here with plenty of background vorticity present along the remnant MCV, but the lack of better moisture and borderline LCLs may keep this threat minimal at best. Further west, a warm front will also move east and may provide enough lift for more thunderstorm development across portions of the west and central, but coverage will be limited as weak transient ridging/height rises try to nudge in. Parameters here will also be less favorable for severe storms. A cold front then approaches from the northwest late this afternoon and into the evening, crossing the state overnight. This afternoon, ahead of the cold front, breezy southerly winds are likely across the central and east. The heat will be the other main story today as a couple of sites have already hit 100 and numerous sites across western and central North Dakota are already in the mid to upper 90s. For your Independence Day, broad ridging and high pressure will lead to a mostly sunny sky with temperatures not quite as hot as today with highs generally expected from the upper 80s to upper 90s. Expect breezy winds again across portions of the central and into the James River Valley, but this time out of the northwest behind the cold front. .LONG TERM...(Sunday night through Saturday) Issued at 244 PM CDT Sat Jul 3 2021 Ridging starts to deamplify again Sunday night as a northern stream shortwave tries to flatten it. This will lead to increasing cloud cover and precipitation chances overnight through Tuesday. Widespread showers are likely with chances of thunderstorms. However, buoyancy will be fairly limited so severe weather is not really a concern. While precipitation will be widespread, it will still be convective/hit or miss in nature but many will see beneficial rainfall. A brief cool down continues through Tuesday when highs will range from the mid 60s across the Turtle Mountains, to the lower 80s across the far southwest. Ridging builds in again on Wednesday, warming back into the mid 70s to mid 80s. Thunderstorm chances return Wednesday night through Friday as a potent shortwave trough approaches. Details remain uncertain regarding amplitude and timing as global models continue to flip flop. Over the past few runs the deterministic ECMWF had started coming in more amplified/stronger and the GFS had backed off. However, today`s 12z deterministic GFS is now the stronger solution with the ECMWF backing off a bit. Taking a closer look at the ensembles, it is evident that we are still a few days away from getting a clear picture of how this system will unfold. However, CIPS analogs and pattern recognition would suggest the potential for at least some severe weather mid to late week, so we will keep an eye on the ensemble trends over the coming days. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 946 PM CDT Sat Jul 3 2021 VFR conditions are expected for the 00Z TAF period. Thunderstorms have all but ended across western and central North Dakota, so the threat of storms at a terminal locations should be very low. Winds will gradually diminish tonight before gradually increasing again on Sunday, especially at KMOT, KBIS and KJMS. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CK SHORT TERM...ZH LONG TERM...ZH AVIATION...CK
Area Forecast Discussion
National Weather Service Cheyenne WY
548 PM MDT Sat Jul 3 2021 .SHORT TERM...(This evening through Sunday) Issued at 130 PM MDT Sat Jul 3 2021 Frontal boundary laying along the Wyoming/Nebraska state line this afternoon. East of the front...dewpoints in the low 60s...while west...mid 40s are prevailing. The exception being right here at Cheyenne where an outflow boundary surged north and raised dewpoints into the mid 50s. Radar showing thunderstorms developing early today...becoming numerous down here over the south Laramie Range and Laramie County. For this afternoon...we need to be on the watch for severe thunderstorms as storms move into the Panhandle later. SPC mesoanalysis showing afternoon surface based CAPE up near 200-2500 J/KG. Outflow boundaries will provide additional shear and low level spin to aid in sustaining thunderstorms. SPC has a Slight Risk for the Panhandle that is looking better by the hour. HRRR simulated radar showing initially discreet cells...bowing out in the Panhandle by 00Z. Maybe a little less convection for Sunday...but still have moisture in place for scattered afternoon storms once again. Best day for storms still looking like Monday when an upper shortwave moves through the area. Increased PoPs over guidance as ECMWF...NAM and GFS all showing fairly widespread QPF. .LONG TERM...(Monday night through Friday) Issued at 335 AM MDT Sat Jul 3 2021 Long Range models in good agreement through next week, showing a trend towards hot temperatures by mid to late week as a strong area of high pressure aloft develops near the four corners region and lifts northeast towards Wyoming and Idaho. The coolest day will be Tuesday as showers and thunderstorms will likely persist through Monday night as a slow moving upper level trough will push southeast across the high plains. Most models show these showers continuing into early Tuesday morning with fog development likely around sunrise. High temperatures on Tuesday may be a few degrees too high in northwest flow aloft, based on model consensus and previous ensemble runs. For now, kept highs in the mid 70s to mid 80s. Again these temperatures may be 3 to 6 degrees too high, especially across the eastern plains. Started lowering POP on Tuesday afternoon and evening since most of the area should be west of the trough axis by then. However, still expect widely scatters showers and thunderstorms near the Colorado border and locations further southeast towards the trough axis. Will likely see a beginning of a weather pattern change on Wednesday as all models show the center of the 595-599dm upper level high drifting northeast towards Wyoming. Highs in the mid 80s to low 90s will be widespread with even warmer temperatures by Thursday and Friday of next week. Increasing subsidence and drier air aloft should suppress deep convection over most of the area. Can`t rule out a few thunderstorms over the mountains and near the Laramie Range, so kept POP around 10 to 15 percent for these areas. Thankfully, the hot weather may be short-lived across the eastern plains with extended models showing a return to northwest flow aloft late next weekend and into next weekend. However, areas further west may still influenced by the strong 600dm upper level high over southwest Wyoming. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 540 PM MDT Sat Jul 3 2021 KAIA will trend MVFR conditions until 01Z due to thunderstorms. Thunderstorms will continue across the region until 03Z in the Nebraska Panhandle. Sites KAIA, KCDR and KSNY will have impacts of gusty winds up to 35kts and small hail. Afterwards, all TAF sites will trend VFR with winds under 14kts. Skies will remain cloudy with mostly SCT clouds sitting at 8-10k ft. && .FIRE WEATHER... Issued at 130 PM MDT Sat Jul 3 2021 Weak monsoonal moisture will remain over the area through Monday with daily chances of afternoon and evening showers and thunderstorms. Best locations for showers and storms will be along and east of the Laramie Range. Best day for wetting rains Monday as we see an upper level disturbance move through that will aid in fairly widespread showers and storms. Warming and drying mid week on into the end of the week as high pressure builds into the area. Could see critical fire weather conditions Thursday and Friday as westerly winds begin to increase and afternoon humidity becomes critical...especially west of the Laramie Range. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...GCC LONG TERM...TJT AVIATION...AW FIRE WEATHER...GCC
National Weather Service Eureka CA
259 PM PDT Sat Jul 3 2021 .SYNOPSIS...Hot and dry weather will persist across the interior through early next week. Coastal areas will remain seasonably cooler with night and morning low clouds and fog, and partial afternoon clearing. && .DISCUSSION...Main concern tonight through Sunday continues to be the potential for thunderstorms and lightning activity across the mountains of northeastern Trinity County. A mid level cyclonic circulation has been advecting mid level moisture above about 15,000 feet northward through the day. Thunderstorm and lightning activity associated with this disturbance has been initiated by daytime ground heating. So far there have not been any lightning strikes away from the terrain, mainly the Sierra Nevada. SREF plumes continue to indicate sufficient CAPE (100J/kg) for thunderstorms this evening, generally above 12kft. This disturbance does not track far enough northward nor does there appear to be sufficient lifting for this CAPE to be realized. Moreover, all the convective allowing models indicate storms occurring well to our east and southeast where the HREF indicates the highest probabilities of nocturnal storms through early Sunday morning. There will be some patches of mid clouds that will drift across Lake and southern Mendocino counties this evening and overnight. This will need to be closely watched for a very low chance (less than 5%) for isolated lightning strike with elevated storms on dry fuels, especially in Lake and NE Mendocino Counties. Otherwise, hot and dry conditions will persist across the interior through early next week as a warm and dry airmass remains over the area. Valleys in Trinity and far NE Humboldt Counties will be the hottest through Monday with highs around 98-104F degrees. Elsewhere in the interior, afternoon high temperatures will generally range from the mid 80s to upper 90s. The heat risk will remain mostly in the moderate category, but there will be localized areas of high risk in Trinity County such as around Big Bar. Interior temperatures should moderate around mid week as a trough moves toward the Pacific NW coast. Overall, temperatures will most likely remain above normal all next week. Significant warming with triple digit interior heat will be possible late in the week and next weekend as the four corners ridge expands west. Marine layer depth and stratus cloud thickness has decreased over the last 24 hours. Low clouds and fog continued to cling to the shoreline and beaches through the day, however. A shallower marine layer will generally result in faster clearing for the coastal river valleys. Persistent areas of stratus and possible fog will likely occur at the beaches. With cloud bases closer to the ground, fog may become dense tonight. HREF probability for dense fog (1/4sm or less) is highest right along or offshore the Mendocino coast tonight and Sunday morning. NAM12 and GFS BUFKIT time-height sections indicate very little or minor changes Sunday through Monday in marine layer conditions. Layer deepening and thicker stratus clouds will be possible around Tuesday. && .AVIATION...Another day, another bout of coastal stratus. There are some notable difference versus yesterday`s stratus. Firstly, per area profiler data, the marine layer has perhaps gotten a bit shallower at the McKinleyville profiler, while the marine layer appears to have gotten a bit deeper at the Bodega Bay profiler. In addition, drier air is advecting S from coastal SW OR across our N coastal waters. 2 large eddies are evident on visible satellite imagery. One is downwind from Pt Saint George WSW of Orick and the other is downwind from Cape Mendocino due W of Ft Bragg. The best chances of ceilings scattering out at KCEC and KACV will likely be over the next few hours, but uncertainty is high and any improvement is likely to be short-lived. Low clouds and fog are expected to push inland again tonight. However, there is some indication of some weak offshore flow at both locations later tonight, and this would act to raise ceilings and improve visibilities a bit if it pans out. For KUKI, another night of mostly VFR conditions is expected. However, low clouds made it just N of the Mendocino county line early this morning, and the latest HRRR guidance is indicating a finger of stratus may make it all the way up the Russian River Valley to the terminal by daybreak. With the slight deepening of the marine layer and the indication of a substantial offshore eddy W of Bodega Bay pumping more low-level moisture from S to N, this appears to be a distinct possibility. Already hinted at this in the 18Z TAF package, and the oncoming shift may need to ramp up low-level cloud cover in the 00Z update. /SEC && .MARINE...Advisory-level northerly winds continue across the N outer waters this afternoon with advisory-level seas and marginal winds across the S outer waters. We extended the Small Craft Advisory for the N inner waters earlier, but this will be allowed to expire at 3 PM. Have extended the advisory for the outer waters through midday Tuesday. Near advisory-level conditions will persist across the outer waters into the middle of the coming week. Northerlies are expected to increase a bit by late Wednesday. Otherwise, a long period SW swell will persist throughout the period, while a mid-period NW swell moves through the waters starting Monday. /SEC && .EKA WATCHES/WARNINGS/ADVISORIES... CA...None. NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until 12 PM PDT Tuesday or PZZ470-475. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
National Weather Service Hastings NE
659 PM CDT Sat Jul 3 2021 .DISCUSSION...(This evening through Saturday) Issued at 331 PM CDT Sat Jul 3 2021 There are a few chances for thunderstorms over the holiday weekend, but, despite this, most areas will probably end up staying dry. Currently, GOES-16 satellite imagery shows fairly shallow cumulus development over the western two-thirds of the forecast area. This should fade with loss of diurnal heating late this afternoon. The areas to focus on for convective development over the next couple hours will be over the Nebraska panhandle and eastern Colorado. These storms may approach western portions of the forecast area this evening, but the consensus is that they will largely dissipate before moving in. That being said, there is a weak upper trough moving through the area, which may be enhanced by remnant outflow or MCV features, therefore a slight chance of thunder was added to most of the area late tonight into Sunday morning. Isolated showers and thunderstorms are expected to redevelop Sunday afternoon and early evening, although latest HRRR and NAMnest runs keep this mostly northwest of the area. Any storms that do mange to develop will have plenty of CAPE to work with, but shear will be limited at only around 20kts. Therefore, we cannot rule out a few strong to marginally severe updrafts, but the overall threat is fairly low. This activity will be largely diurnally-driven so dry conditions should return overnight. The daytime of Monday should also remain dry. With rising heights aloft, we should see temperatures push into the mid to upper 90s across the area. Heat index values are expected to remain just short of advisory criteria (105 degrees), but it will definitely feel hot due to very light surface winds. Monday evening and overnight, a few showers and thunderstorms could move into northern portions of the forecast area as an upper trough pushes to our north. Better chances for thunderstorms arrive on Tuesday and Tuesday night as the trough axis and surface cold front move through the area. This has resulted in fairly widespread 50-60 PoPs, but total QPF amounts are not overly impressive. The EPS ensemble only has 0.25-0.50" across the forecast area through this period. A few showers or storms may linger into Wednesday, but most of the area will dry out by the afternoon. The post-frontal airmass will bump our temperatures down to slightly below normal. Highs are expected to be in the low to mid 80s. This cooldown will be short- lived though, as temperatures are expected to rebound to the 90s by Thursday or Friday. Another cold front is then expected to push through the area in the Friday to Saturday timeframe, ushering in noticably cooler and drier air for next weekend. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday) Issued at 654 PM CDT Sat Jul 3 2021 VFR conditions forecast. Although VCTS is mentioned overnight, we will not likely see this convection make it that far east. Nonetheless, it is included just in case as there is an mid-level perturbation that could help sustain convection. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...Mangels AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Lake Charles LA
956 PM CDT Sat Jul 3 2021 .UPDATE... A stalled frontal boundary continues to bisect the region as evidenced by the nearly fifteen degree spread in dewpoint from AEX to LCH. However, in typical diurnal fashion, the vast majority of precipitation has pushed off into the gulf this evening where it is expected to remain overnight. PoP guidance for Independence day has been coming in lower this evening so opted to lower PoPs through the morning while maintaining scattered wording through the afternoon. This was the only significant change to the forecast as other parameters are in line. Jones && .PREV DISCUSSION... /issued 644 PM CDT Sat Jul 3 2021/ AVIATION...Widespread rain and storms will decrease through the evening, however convection will again increase in coverage tomorrow as heating increases. Spotty reductions in vis and ceilings can be expected. Light winds will become more northeast tonight and gradually south through Sunday. PREV DISCUSSION... /issued 359 PM CDT Sat Jul 3 2021/ DISCUSSION... SHORT TERM (Today through 12Z Tuesday)... The surface frontal boundary has been continuing to make its way south into our area today and is expected to stall over our area this evening. This has led to elevated shower and thunderstorm chances throughout the day today with the interaction of moisture from the Gulf of Mexico. Showers and thunderstorms will be expected to diminish over land this evening due to weakening convergence boundaries with the loss of daytime heating as well as the stalling front reducing any forced uplift over the area. The latest run of the HRRR (18Z) shows convection forming primarily along the I-10 corridor and to the south for the remainder of this afternoon into this evening, with inland storms dissipating later in the evening. The stalling frontal boundary will continue to provide elevated precipitation chances overnight primarily for offshore areas. However, a few showers could develop near the coast as well during this time period. The pressure gradient has remained weak which means winds have been fairly light and will continue to be over the next few days. The front will remain stalled over our area and eventually dissipate by 12Z Tuesday. The lingering frontal boundary will lead to elevated precipitation chances most notably during the daytime hours on Sunday and Monday (aided by daytime heating). Flooding will continue to be a concern over the next few days due to the elevated chances for showers and thunderstorms combined with the already saturated ground. Since flow will be light, storms that develop may be slow movers and cause localized flash flooding. 55 LONG TERM (Tuesday through Sunday)... Unfortunately, no real change to the long term period as the persistent wet pattern looks to continue. On Tuesday, we will be watching Elsa at it moves into the eastern Gulf. Although no direct impacts to the CWA are expected, some downstream effects, mainly in regards to elevated rain chances, are possible. With Elsa to our east, we will remain under a persistent upper level weakness/trof over the Southern Plains/Western Gulf. This trof in combination with a deep influx of moisture through the lower levels will result in another day of widespread showers and thunderstorms across SE TX/SW LA, especially during peak heating hours. Coverage should largely taper off with the loss of heating, however, with the favorable synoptic set up a better than normal coverage of showers and thunderstorms is likely overnight as well. Heading into the midweek, the wet pattern continues as the upper level weakness remains overhead and PWATs hover around 2 inches. So with minimal to no capping and plenty of moisture available the atmosphere will remain primed for widespread convection. Still expecting the same general pattern of highest POPs in the afternoon, tapering off overnight, both Wednesday and Thursday. By Friday, the pattern looks to break a bit as the sub-tropical ridge begins to build across the Gulf Coast. Ridging should remain overhead through the weekend, providing some relief from the extremely wet pattern we`ve been experiencing. That said, still carrying small POPs Fri- Sun, but coverage should be a lot more isolated. Unfortunately, with the wet pattern ending it looks like a return of highs in the low to mid-90s by the end of the period. 17 && .PRELIMINARY POINT TEMPS/POPS... AEX 68 94 72 93 / 0 10 10 50 LCH 73 91 74 89 / 60 40 40 80 LFT 72 90 73 88 / 50 30 40 80 BPT 73 90 73 88 / 70 60 50 80 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
935 PM EDT Sat Jul 3 2021 .SYNOPSIS... An upper trough located overhead today will pass off to our north and east tomorrow. High pressure will build in early next week before a cold front approaches the area during the middle to latter portions of the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... A deep upper level trough by July standards is slowly progressing off to our east, with a closed low centered over New England. Mesoanalysis shows an area of low-level convergence and positive vorticity advection on the back side of this system, with the axis of focus across central Maryland. With several hundred J/kg of CAPE remaining in place, showers and a few embedded thunderstorms continue to develop within this axis. Locally gusty winds remain possible with this activity, though overall intensity is slowly decreasing with loss of daytime heating. While brief heavy rain is also possible, those rates are rather short in duration and should not lead to flooding. HRRR has been consistent in allowing any remaining showers to dissipate between midnight and 2 AM, coincident with the exit of the vort max. The dissipating showers will give way to mostly clear skies overnight. Temperatures overnight will drop back into the upper 50s to mid 60s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... 12z CAMs hint that showers or even a weak thunderstorm may form late tonight in PA as a disturbance descends down the backside of the departing trough. The CAMs have this activity moving into the WV Panhandle around daybreak, before progressing off toward the south and east toward the DC Metro during the late morning/early afternoon hours, weakening as it does so. Additional development of showers and thunderstorms is somewhat uncertain tomorrow afternoon as heights aloft rise as the trough pulls away to our north and east. As temperatures warm aloft, we`ll be left with little to no instability to the east of the Blue Ridge, even after daytime heating. To the west of the Blue Ridge, the rising heights will be offset more by advection of warm/humid air spilling in from the Ohio Valley. The NAM is a bit of an outlier at the moment, but shows around 1000 J/kg of MLCAPE developing to the west of the Blue Ridge. It`s questionable as to whether a storm will even form within the zone of height rises, but if one were able to, and that instability was realized, a supercell can`t be ruled out to the west of the Blue Ridge given the 40 knots of the northwesterly shear in place. To the east of the Blue Ridge any showers or storms should be rather weak, with the virtually non-existent instability. Any activity that develops tomorrow afternoon should rapidly weaken and dissipate in the evening with loss of daytime heating. Temperatures will run a bit warmer tomorrow with highs in the 80s as dewpoints creep up into the lower to middle 60s. Weak ridging aloft will build into the area on Monday as much warmer and humid air advects into the area from the west. With ridging in place, most of the area is expected to remain dry, but terrain circulations may produce a few airmass thunderstorms over the mountains in response to daytime heating. High temperatures will reach into the upper 80s to near 90, with dewpoints climbing into the upper 60s. && .LONG TERM /TUESDAY THROUGH SATURDAY/... Long term starts out with a ridge over the mid-Mississippi Valley extending east into the Atlantic. This ridge will gradually shift eastward as a trough digs over the northern Plains Wednesday and Thursday before pushing east across the northeast Thursday night. Another ridge will briefly build behind that trough while another stronger trough digs in the plains Friday into Saturday. At the surface, we will stay in a weak ridge of surface high pressure Tuesday and Wednesday with hot temperatures and likely some mainly terrain forced convection. Thursday into Thursday night, a cold front and possibly some remnants of Elsa will cross the region, bringing better chance of clouds and storms. Partial drying behind it Friday and Saturday, but the front stalling out could cause the risk of showers and storms to linger. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Showers and perhaps an embedded thunderstorm will continue to stream down a convergence axis between DCA and BWI this evening, but should dissipate between midnight and 2 AM. Brief visibility reductions and gusty winds up to 30 mph will be the main threats. Otherwise, VFR conditions are expected through the night with light and variable winds. Sunday, showers or a storm appear possible at any terminal, but the overall coverage is expected to be lower compared to today. Showers Sunday could potentially start earlier, especially near MRB. Guidance is beginning to hint that there could be low clouds or fog in places Sunday night, but there`s still a fair amount of spread. VFR conditions are expected again on Monday with any storms staying to the west of the terminals over the mountains. Mainly VFR Tuesday/Wednesday outside of any patchy morning fog or afternoon thunderstorms, which should be fairly limited in coverage. && .MARINE... While the threat of more numerous strong, gusty storms is diminishing this evening, showers and perhaps an isolated stronger storm will remain possible through 2 AM. Various outflow boundaries are also pushing across the waters, which will make for erratic and gusty winds even away from precipitation cores. Later tonight, this activity should dissipate, leaving sub-SCA conditions through Monday with somewhat variable wind directions. Winds mostly sub-SCA, but southerly channeling could bring marginal SCA gusts at times. Slight risk of a thunderstorm, especially Wednesday afternoon, which could bring gusty winds. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...KJP NEAR TERM...ADS/KJP SHORT TERM...KJP LONG TERM...RCM AVIATION...ADS/RCM/KJP MARINE...ADS/RCM/KJP
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 305 PM CDT Sat Jul 3 2021 Temperatures and precipitation chances should provide the primary forecast challenges the next few days. Will run a heat advisory for Knox and Cedar counties from 1 pm to 8 pm Sunday. The following features were noted in the large scale pattern at 12Z this morning. Winds at 300 mb were pretty light (generally under 50 knots) across the central and western US, with stronger winds from Hudson Bay south into the Tennessee Valley. At 500 mb, a ridge was in place from Mexico up into the Four Corners region, with an extension of that ridge across NE and MN. 12 hour height falls of 50 meters or more extended from Saskatchewan down into ND. Warmest air at 700 mb was back across the Rocky Mountain region, with highest moisture content at that level over Mexico, Texas and the southern parts of NM and AZ. At 850 mb, there was a trough over the High Plains and a weak ridge from OK up into MN. A poleward transport of moisture was noted in the 850 mb plot (and to a certain extent reaching up to near 700 mb) from the TX panhandle into western KS and central NE. That was also shown in recent satellite loops this afternoon. 3 PM CST temperatures were in the mid 80s to around 90 across eastern NE and southwest IA. Earlier I added some low POPs to parts of northeast NE for later tonight, based on signals from the GFS and a few of the CAMs (mainly RAP and 4 km NAM Nest). The evening will probably be dry, with any storms confined farther to the west. But that deeper moisture mentioned earlier will be working into our area. Isentropic forecast plots around 315K show some weak lift and specific humidity values of 4-8 g/kg. If isolated showers or storms can develop later tonight, they could linger into mid morning before dissipating. Otherwise look for clear to partly cloudy skies tonight, and lows mostly from 64 to 69. Patchy fog has occurred the past few nights and could occur late tonight, especially with possible enhancement from fireworks smoke. For Sunday, the period from mid morning to mid afternoon should be mainly dry. But as mentioned in the HWO, storms could work into or develop across parts of northeast NE in the mid to late afternoon and continue into the evening. Shear and instability suggest a few storms could approach severe limits. Highs will be mostly in the 88 to 94 degree range, with warmer readings near the SD border. Weak mid level isentropic upglide will slowly shift southward across the area Sunday night, so have those low POPs moving into southeast NE and southwest IA after dark. Lows will be a bit warmer, mostly upper 60s and lower 70s. By Monday, the mid level pattern will have changed a bit. There will still be a ridge across Mexico and the southwest US, but northwest flow will be in place across the northern Plains. Our area will be on the southern edge of that stronger flow. But as the week goes on, the flow at the 500 mb level will increase, and be mostly from the northwest. Any disturbances will be hard to time exactly, but we will have some decent rain chances, especially Tuesday and Tuesday night as mid level moisture, a couple of ripples and a low level front interact over the Central Plains. Hopefully we can get widespread beneficial rain amounts. Look for highs Monday in the lower and mid 90s. Tuesday should be cooler in our northern counties (85 to 90) with upper 80s to mid 90s south. Wednesday will be cooler yet, with highs from the upper 70s to mid 80s. Highs should reach the 80s Thursday and then upper 80s to mid 90s by Friday. Toward the weekend, the mid level flow turns more to the north as a trough develops from the Great Lakes region down toward TX and the ridge to the west retrogrades a bit toward the southern parts of CA and NV. This may drop highs back down into the 80s Saturday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 611 PM CDT Sat Jul 3 2021 VFR conditions will prevail through the period. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...Heat Advisory from 1 PM to 8 PM CDT Sunday for NEZ011-012. IA...None. && $$ DISCUSSION...Miller AVIATION...DEE
Area Forecast Discussion...UPDATED
National Weather Service Pendleton OR
854 PM PDT Sat Jul 3 2021 .UPDATE...Limited sensible weather concerns with concerns revolving around fire weather (dry and windy) and moderate winds in the Gorge. Latest satellite imagery shows some weakening convection across east central OR south and east of the southern Blues and Strawberry mountains with mainly inter/intra cloud lightning associated with it. Otherwise, clearing skies, except lingering high clouds across parts of northeast OR. The going forecast was largely on track with updates mainly revolving around capturing near-term trends and updating for the latest guidance. Strongest winds tomorrow in the Columbia Gorge spilling into north central OR and the Kittitas Valley with gusts as high as 30-35 mph with a decent signal present in both the HREF and NBM. Thus confidence high in these winds. Otherwise, elevated fire weather conditions owing to the overlap of breezy conditions and low afternoon humidity tomorrow across parts of the east slope of the OR Cascades and far western parts of the Basin. && .AVIATION...00Z TAFs...VFR conditions expected over the next 24 hours. A few upper level clouds are noted across Central Oregon, as well as a chance for a few passing thunderstorms this evening across the Strawberry Mountains. BDN and RDM should be west of this activity. Haze remains possible as well from fires. Breezy winds 12-20kts this evening continue for DLS/RDM/BDN/PDT, though all sites except for DLS should see the usual diurnal weakening of these breezes overnight. && .PREV DISCUSSION... /issued 157 PM PDT Sat Jul 3 2021/ SHORT TERM...Tonight through Monday night. Sunny skies across most of the region this afternoon with temperatures in the 90s. A weak system is moving across southeastern Oregon. Satellite showing cumulus development and could have isolated showers of a thunderstorm over central Oregon toward the John Day highlands through the evening. This cloudiness will dissipate late evening with mainly clear skies overnight. A weak upper level trough pattern over the Pacific northwest with water vapor imagery indicating a short wave moving through southern BC and the Pacific northwest late tonight into Sunday. This system is dry and only impacts will be westerly winds 10-25 mph. Heights increase some as upper ridge builds on Monday. The flow aloft becoming more southwesterly with an upper low off the California coast. Expect another sunny and hot day with highs in the 90s. Hazy conditions with smoke aloft will continue this evening and overnight. Stronger winds aloft Sunday should help improve conditions with HRRR showing smoke pushing off to the east. A return to southwest flow Mon will likely bring northern California wildfire smoke back into the region. 94 LONG TERM...Tuesday through Saturday...Ensembles and deterministic guidance in good agreement that hot and dry conditions will continue into next weekend. Guidance in good agreement that transient ridging will move across the forecast area Tuesday, followed by a shortwave trough that will lift northeast into northern WA and southern BC late Tuesday through Wednesday. ECMWF and GEFS member spreads instill high confidence in a 3-5 degree warm up Tuesday afternoon into the upper 90s to 105 with majority of individual members within 5 degrees of each other. By Wednesday, shortwave trough moving north of the forecast area will help to knock temperatures down a couple of degrees, though some member spread for Wednesday is greater with a majority within 10 degrees of each other for some of our OR and WA cities. The shortwave trough passing across WA will also restrengthen the marine layer west of the Cascades, which will induce breezy winds through the Cascade gaps and Gorge Wednesday. Beyond Wednesday, the general consensus amongst deterministic and ensemble guidance is for another amplified ridge to develop along the ID panhandle, while the marine layer slowly weakens. The return of an amplified ridge would see another warm-up into the weekend, however, temperatures at this time are only forecast to reach into the upper 90s to 105 Friday and Saturday afternoon. Otherwise, the weakening marine layer west of the Cascades will still induce breezy to locally breezy winds through the Cascade gaps and the Gorge each afternoon. Lawhorn/82 && .PRELIMINARY POINT TEMPS/POPS... PDT 60 95 58 96 / 0 0 0 0 ALW 63 96 64 98 / 0 0 0 0 PSC 62 99 62 100 / 0 0 0 0 YKM 61 96 61 97 / 0 0 0 0 HRI 62 99 62 100 / 0 0 0 0 ELN 60 91 59 94 / 0 0 0 0 RDM 49 92 49 94 / 10 0 0 0 LGD 54 91 53 93 / 10 0 0 0 GCD 55 93 56 95 / 10 0 0 0 DLS 60 92 60 95 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Heat Advisory until 8 PM PDT Sunday for ORZ041-044-049-505-507- 508-510-511. WA...Heat Advisory until 8 PM PDT Sunday for WAZ024-026>029. && $$ SHORT TERM...94 LONG TERM....82 AVIATION...87 UPDATE...80
Area Forecast Discussion
National Weather Service Phoenix AZ
415 PM MST Sat Jul 3 2021 .UPDATE... Updated Aviation && .SYNOPSIS... Chances for showers and thunderstorms will continue through this weekend with decreasing chances by Monday followed by little chance for the middle of next week. Storms will be common over the higher terrain and more isolated on the lower elevations. Gusty winds with localized blowing dust and localized heavy rainfall capable of producing flash flooding will be the main impacts. Although a general drying and warming trend with above normal temperatures is expected next week across most of the region, isolated storm chances are likely to persist over the eastern Arizona high terrain. && .DISCUSSION... Latest signals from observational and model data point to an active evening across south-central Arizona. The atmosphere is exceptionally moist today with PWATs ranging from 1.5 to 2.0 inches, placing it in the 95th percentile of climatology for the day. Latest RAP streamline analysis depicts the inverted trough across southeastern Arizona, situated between two anticyclones, one across western Texas and another across northern Arizona. The resulting mean layer flow is out of the southeast, which will be favorable to maintain the deeper moisture. Surface dewpoints have only dropped a few degrees this afternoon and remain in the lower 60s. Convection has already initiated along the Mogollon Rim, and across portions of southeastern Arizona near a well-defined vort max. Morning KPHX sounding indicated relatively strong easterly flow of 30 kt at 600 mb, which will help to steer activity into south- central Arizona this evening. Consensus from the CAMs including the HRRR suggests an outflow boundary from storms in the higher terrain will also provide the lift necessary to overcome any low-level CIN in the Valley, while also allowing new cells to propagate rapidly into the deserts south and west of Phoenix. Consequently, PoPs were increased to around 50 percent in the Phoenix area, and as high as 70 percent near Casa Grande. HREF ensemble max gusts are around 50 mph in the strongest storms, and this is not entirely surprising given the anomalously rich low- level moisture and subsequent dearth of DCAPE. Nevertheless, strong wind gusts will still be possible in the vicinity of the outflow boundary as it descends into the lower deserts. However, the greater threat will likely be the potential for flash flooding, particularly across the higher terrain of Gila County and within the recent burn scars. Latest guidance suggests rain rates could reach 1-3 in/hr in the strongest cells. && .PREVIOUS DISCUSSION... A shift in the pattern is expected to begin on Sunday with the drier southerly flow across the western deserts to begin expanding eastward late in the day as well as drier northwesterly mid level flow beginning in the afternoon. Abundant boundary layer moisture will still be present over much of the region on Sunday, but the drying aloft will begin to have a noticeable effect on storm activity, especially across the lower deserts. Showers and storms will again be likely across the eastern Arizona high terrain Sunday afternoon, but they will likely have a more difficult time maintaining their westward push into the south-central Arizona deserts. Can`t rule out some isolated to scattered storms affecting the Phoenix area Sunday, but chances mostly drop into a 15-20% range. The westerly drying will continue early next week, likely ending storm chances completely across the lower deserts as early as Monday. Afternoon surface dew points are forecast to drop into the 40s across the western deserts on Monday and then across the south- central Arizona deserts on Tuesday. The upper level ridge center is also seen shifting into Nevada while also strengthening, likely leading to H5 heights increasing to 592-595dm across the Desert Southwest. The drying boundary layer and increased heights aloft should push daytime highs to around 110 degrees in the Phoenix area to 110-113 degrees across the western deserts. So far NBM guidance has been keeping temperatures just below excessive heat levels for next week, but if the upper end of guidance proves true then some heat products may be needed. After a few days of likely minimal monsoon storm activity confined to the eastern Arizona high terrain, there are signs of some moisture return and expansion into the lower deserts at some point later next week. However, the flow pattern through next weekend does not look very conducive for deep moisture advection, likely limiting storm chances across the lower deserts. && .AVIATION...Updated at 2315Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: HREF output shows gusty N/NE winds moving through the metro between 01Z-04Z with greater than a 70% chance of gusts above 30kt. There is also multiple outflows moving in from the south which could create collisions and erratic directions. NBM probabilities of storms at any location is better than 50% with HREF neighborhood probabilities about the same. Kept VCTS along outflow, then VCSH and variable winds later this evening. Some dust could be picked up along outflows as well. Cigs 8K-12K ft AGL are forecast by NBM this evening and overnight. NBM has nearly 30% chance of rain through Sunday morning, but cut off mention shortly after midnight. NBM shows west winds and storm chances less than 15% Sunday afternoon and evening. Southeast California/Southwest Arizona including KIPL and KBLH: Southeast to southwest winds are forecast during the periods with speeds mostly below 12kt. HREF output shows a weakening outflow boundary hitting KBLH later tonight though probabilities of greater than 30kt is 10% or less. Cloud heights will be 12K ft and above with NBM showing less coverage tomorrow. && .FIRE WEATHER... Tuesday through Saturday: Moisture will decrease gradually through the midweek period, which will generally confine the threat of storms to eastern Arizona. A return of deeper moisture looks possible late next week with storm chances potentially increasing and expanding westward across Arizona. Temperatures for the bulk of the period will run a few to several degrees above normal. Min RH values will drop into the 10- 15% range over southeast California and southwest Arizona and 15-25% range over south central Arizona with the highest values over the higher terrain north and east of Phoenix. Max RHs will recover into the 30-45% range for most locations. Apart from thunderstorms, wind patterns will follow diurnal patterns. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Hirsch PREVIOUS DISCUSSION...Kuhlman AVIATION...18 FIRE WEATHER...Hirsch/Hopper/Kuhlman
Area Forecast Discussion
National Weather Service Pueblo CO
736 PM MDT Sat Jul 3 2021 .UPDATE... Issued at 735 PM MDT Sat Jul 3 2021 Updated severe thunderstorm watch, dropping El Paso and Pueblo Counties. Strong to severe storms will still be possible over the far east plains through this evening. && .SHORT TERM...(This evening through Sunday) Issued at 358 PM MDT Sat Jul 3 2021 Main Forecast Concerns/Challenges: 1) Increased threat for strong to severe storms through mid to late evening across the plains, mainly from Colorado Springs to Pueblo and areas east. 2) Returning thunderstorm chances on Sunday, some of which could become strong to severe. Latest trends with thunderstorm development along with thermodynamic and wind fields indicate an increased threat for strong to severe storms this afternoon into mid to late evening. The previous thoughts that the instability would lower across the I-25 corridor from around Pueblo to Colorado Springs has changed, with latest RAP analysis indicating 500-1000 j/kg of MLCAPE remaining in place along with 25-35 kt of shear. This combined with steep mid/low lapse rates, dewpoints around 60 degrees, and persistent/focused low to mid level convergence will all support thunderstorm development across Pueblo and El Paso county this afternoon into early to mid evening. The current development in eastern Fremont county will continue to shift more east here in the near term, though may still become strong to severe before exiting the county. Large hail and damaging winds will be the main threats with any severe storm in this location this afternoon. Some isolated storms may occur further to the south, over the far southern I-25 corridor, but anticipate these storms to remain sub severe. Expect all of this development to diminish by early to mid evening, with focus shifting to likely upstream thunderstorm development across north central CO. These storms, riding along a southward moving mid level trough and within surface trough axis, will dive southeast into eastern Crowley and Kiowa counties this evening, around 6-8 pm. High dewpoint air in the 60s, MLCAPE values in the 1000-1500 j/kg range, and bulk shear in the 30-40 kt range will support a continued threat for severe storms during this time. Still think that half dollar size hail and winds over 60 mph will be the main risks. This development will shift southeast with time, moving through other areas along and east of a La Junta to Kim line. Guidance varies with the intensity of the storms by late evening, likely given the later time of the day. However, think there will remain a chance for these storms to remain severe as they push through all of far southeast CO very late this evening. Another day of thunderstorm development is expected across southern CO on Sunday, also with the threat of strong to severe storms. Can`t rule out a strong to severe storm anywhere across the plains Sunday afternoon, though a higher risk for severe storms is expected across the far eastern plains where stronger focus, higher dewpoint air, and much higher instability will reside. .LONG TERM...(Sunday night through Saturday) Issued at 358 PM MDT Sat Jul 3 2021 Main Forecast Concerns/Challenges: 1) Severe storms possible over the southeast corner Sunday night 2) Burn scar monitoring needed Monday and Tuesday Sunday night...Models are indicating that through the first half of the night, activity will likely persist along the I-25 corridor and the eastern plains, with a chance for stronger to severe storms over the southeast corner. SPC painted the area with a Slight chance for severe storms, and given the good 0-6km bulk shear and heavy CAPE forecast for that area, this looks reasonable. Storm threats will be hail over an inch in diameter and strong wind gusts in excess of 60 mph, along with the possibility of an isolated tornado. Activity will taper off after midnight, with overnight lows in the 50s for the high valleys and 60s for the plains. The warmest temps will be along the CO/KS border where dewpoints are forecast to be the highest. Monday and Tuesday...Models are showing run-to-run consistency on showing Mon and Tue as potential heavy rain days for the mts and I- 25 corridor. The upper ridge of high pressure over the Four Corners will edge to the northwest, allowing an upper disturbance to cross the northern Rockies on Monday. This upper level support, combined with abundant moisture and easterly winds through the column, will help initiate more convection over the mts and adjacent plains Monday aftn and eve. As this disturbance continue east-southeast overnight, a cold front will push into eastern Colorado early Tuesday, setting up for a slightly cooler day but with another enhanced round of convection firing off of the higher terrain by midday. Area burn scars will need to be monitored both days. As for temps, the high valleys will warm into the 80s both days. Across the plains, expect the mid 80s to mid 90s on Mon, then 80s on Tue. Wednesday...This looks like the driest day of the extended forecast, as the upper high positions right over the Four Corners. Expect isolated convection over the higher terrain through the aftn and early eve, with high temps in the 80s for most locations. Thursday through Saturday...Latest long range models are now showing the upper high wavering and trying to slide back to the west. Another shortwave crosses the northern Rockies Thu, then the Dakotas on Fri, which would help provide the needed lift for enhanced convection into the weekend, if the upper ridge does move to the west. For now, the extended procedure indicates that very hot temps will return to the eastern plains Thu and Fri, with isolated to low end scattered convection each day over the higher terrain. On Sat, temps cool by about 10 degrees across the plains along with greater convection chances as the upper ridge pushes towards the West Coast. How this ends up remains to be seen, but models do indicate that a continued busy pattern may be setting up for the region. Moore && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 641 PM MDT Sat Jul 3 2021 KCOS: VFR conditions are expected over the next 24 hours. Thunderstorms may impact the terminal over the next few hours, but are expected to stay to the north/east and weaken. Should a thunderstorms impact the KCOS site, the primary threats would be gusty winds and small hail, with frequent lightning. Otherwise expect winds to become light overnight before increasing in magnitude tomorrow afternoon. Thunderstorms will again pose a risk to KCOS during tomorrow afternoon, with the primary threats being gusty winds and lightning. KPUB and KALS: VFR conditions are expected over the next 24 hours. Winds will become light and variable overnight, before increasing in magnitude tomorrow afternoon. Thunderstorms will pose a risk at both TAF sites, but especially KPUB during the afternoon tomorrow. Primary threats at this time look to be gusty outflow winds and lightning. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GARBEROGLIO SHORT TERM...RODRIGUEZ LONG TERM...MOORE AVIATION...SIMCOE
Area Forecast Discussion
National Weather Service Sacramento CA
217 PM PDT Sat Jul 3 2021 .SYNOPSIS... Isolated mountain thunderstorms mainly along and east of the Sierra Crest this afternoon and evening. Some storms may linger overnight. Elsewhere, quiet and warm weather continues. && .DISCUSSION... Early this afternoon, visible satellite shows a line of mid to high level clouds moving northward across the Central Valley and some building cumulus over the Sierra Nevada. The Salt fire is also noted in northern Shasta County with onshore winds pushing smoke mainly to the north. Moisture advection associated with the high over the Desert Southwest will lead to another day of scattered to isolated thunderstorm chances over the Sierra Nevada. The best chances this afternoon and evening will be over or east of the crest with the threats with storms being lightning, gusty winds, and brief downpours. The Valley will see some additional cloud cover as well this evening into tomorrow morning. Convection may linger through tomorrow morning as a weak shortwave rotates around the high pressure. Both the 3-km NAM and HRRR indicate isolated showers and storms continuing after midnight, possibly reaching into the foothills of the Sierra Nevada and southern Cascades. The Desert high pressure moves eastward a bit tomorrow limiting thunderstorm chances to over and east of the Sierra crest over Alpine and Tuolumne Counties. From here, high pressure extends back into the area early next week bringing the return of dry weather with near to slightly above normal temperatures. && .EXTENDED DISCUSSION (Wednesday THROUGH Saturday)... The Desert SW high will continue to be the main focus during the extended period. A trough tracking through the PacNW will flatten out the ridge some and push it back to the east a bit on Wednesday. This will bring similar highs to Tuesday. As we head into the later part of the week the ridge will begin to build back into NorCal and we will see warming temperatures. By next weekend the ridge will be far enough to the west that it will cut down onshore flow and flow through the Delta resulting in widespread triple digits across the lower elevations. Mid level moisture will be low and no rain or thunderstorm chances are expected for the extended period. -CJM && .AVIATION... VFR with mid level moisture from the Desert SW lifting Nwd over Norcal through Sun morning with occasional CIGS 150-250 at TAF sites. Conditions becoming mainly SKC after 15z Sun. Wildfire smoke from Salt WF in Shasta Co may drift over the KRDD airfield as drainage winds redevelop overnite causing MVFR conditions in FU/HZ. Over Siernev, SCT-BKN afternoon cumulus with bases 050-070 and isolated to clusters of thunderstorms developing mostly near the Crest. Storms may continue/develop overnite due to elevated instability as upper air disturbance moves from the KMTR area NEwd into Plumas Co overnite. Influx of mid level moisture with dry sub-cloud layer could result in locally gusty thunderstorm downdraft winds G30-40 kts. Small cores of brief downpours also possible reducing VSBYS to MVFR at times. Less areal coverage of storms W of the Crest expected on Sun. SWly G35 kts through Carquinez Strait and into the Delta at times with CIGS AOB 015 spreading inland aft 03z and retreating to the coast by 21z through the weekend. Density altitude 3000-4000 ft over Nrn Sac Vly TAF sites during late afternoon/early evening hours through the weekend. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Las Vegas NV
843 PM PDT Sat Jul 3 2021 .SYNOPSIS...A mix of clouds and sun along with a few isolated showers will be possible across the Mojave Desert and southern Great Basin through Sunday evening. Isolated storms with heavier downpours and gusty winds are possible in Mohave county. Drier conditions resume early next week with temperatures warming up. && .UPDATE...Thunderstorm outflow from storms over Yavapai County in Arizona this afternoon pushed into southern and central Mohave County early this evening producing localized winds to near 50 mph. The outflow lost momentum as it moved west across the county with gusts reaching only 15-20 mph in Lake Havasu City through 830 pm. For the rest of the night, the latest NBM along with the HRRR have light shower activity developing across parts of Clark, Nye, and Lincoln counties. The shower activity may produce gusty winds and a few claps of thunder but very little rain is expected. Otherwise, expect mainly clear conditions across the western portions of the forecast area overnight with partly to mostly cloudy skies in the central and eastern portions of the area. The updated forecast for the overnight period is out. && .PREVIOUSLY ISSUED DISCUSSION... .SHORT TERM...through Sunday night. A couple areas of focus through this evening. The first is across the Mojave Desert region (mainly west of Las Vegas) where some mid- level moisture and a weak impulse entrained in the flow are resulting in some light shower activity. Instability across the region remains very low, but enough mid-level instability has been present for a handful of very isolated lightning strikes, mainly near Amboy and the Halloran Summit area. This activity will continue to develop northward this evening, becoming focused across central Nye county with isolated showers stretching as far south as the Mojave Preserve. Any precipitation amounts will be very light (not much more than sprinkles for most areas) though a hundredth or two is possible in the higher terrain. Second focus area is further east across Mohave County. Thus far today conditions have remained dry and stable, but convection is on the increase across the Mogollon Rim and the mountains of Yavapai county currently. With a mid-level easterly flow of 15-20 knots, storms organizing in Yavapai county will enter southern Mohave county later this afternoon. Best chances are mainly from Kingman southward, as instability drops off quickly with north and westward extent. Storms entering Mohave county this evening will likely decay quickly much beyond the US-93 corridor, but gusty outflow winds remain possible as they push eastward towards the Colorado River. On Sunday, mid-level moisture will remain abundant across the region, though instability will still be quite limited. The end result is considerable cloud cover to start the day, with the only exception being our far western zones near the Sierra. Isolated rain showers will continue, though again more likely sprinkles and virga than actual measurable rain given the relatively dry lower levels. A rumble of thunder or two will remain possible. Clouds will thin out late in the day as drier air works in and deeper mid level moisture lifts to our north and east. .LONG TERM...Monday through Saturday. High pressure shifts westward early in the week, which will induce a more subsident and dry weather pattern Monday and Tuesday, and this is when ensemble guidance suggests our regional precipitable water values will bottom out. As such, fairly confident on dry conditions area-wide Monday and Tuesday. Additionally, temperatures will climb several degrees above normal with parts of the Mojave Desert and Colorado River Valley creeping into the high heat risk category. Heat amplifies further late in the week and into the weekend as high pressure strengthens over the southwest. However, at the same time, monsoonal moisture pooled in northern Mexico will begin to creep back into Arizona. This could set the stage for a more active thunderstorm pattern by next weekend, at least across Northwest Arizona, and could also influence the amount of warming we would otherwise see into next weekend. Given the amount of uncertainty, the forecast remains generally dry through next weekend, with very hot conditions. Given the upcoming several day stretch of hot weather, and somewhat elevated dewpoints expected during the heat spell, high heat risk is a concern and excessive heat products will likely be considered in future shifts. && .LONG TERM...Monday through Saturday. High pressure shifts westward early in the week, which will induce a more subsident and dry weather pattern Monday and Tuesday, and this is when ensemble guidance suggests our regional precipitable water values will bottom out. As such, fairly confident on dry conditions area-wide Monday and Tuesday. Additionally, temperatures will climb several degrees above normal with parts of the Mojave Desert and Colorado River Valley creeping into the high heat risk category. Heat amplifies further late in the week and into the weekend as high pressure strengthens over the southwest. However, at the same time, monsoonal moisture pooled in northern Mexico will begin to creep back into Arizona. This could set the stage for a more active thunderstorm pattern by next weekend, at least across Northwest Arizona, and could also influence the amount of warming we would otherwise see into next weekend. Given the amount of uncertainty, the forecast remains generally dry through next weekend, with very hot conditions. Given the upcoming several day stretch of hot weather, and somewhat elevated dewpoints expected during the heat spell, high heat risk is a concern and excessive heat products will likely be considered in future shifts. && .AVIATION...For McCarran...Mid level moisture moving over southern Nevada will produce SCT-BKN clouds with bases 12-13 kft AGL today and tonight but there is very little chance of showers impacting the terminal area, although an isolated storm can`t be ruled out over the Spring Mountains this afternoon. Southwest winds 15-25 kts will prevail into this evening before diminishing, but still remaining southwest overnight. Southwest winds will remain in place Sunday, but speeds are expected to be around 10-15 kts. Thunderstorms are expected to develop over portions of northwest Arizona this afternoon and although they are not expected to impact southern Nevada, it`s possible that some southeast outflow winds up to 20 kts could reach the airport this evening. Confidence is low in this occurring. For the rest of southern Nevada, northwest Arizona and southeast California...A southeast flow aloft will bring mid-level moisture over the region today with SCT-BKN clouds with bases around 15 kft MSL. Isolated showers and thunderstorms can be expected this afternoon over portions of Inyo, central Nye, and Esmeralda Counties. Isolated storms will also be possible across southern Mohave County. Main threat from these storms will be gusty winds to 35 mph. Outside of any storms, look for southwest winds 15-25 kts && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Salmen DISCUSSION...Outler AVIATION...Gorelow For more forecast information...see us on our webpage: or follow us on Facebook and Twitter