Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/15/22


Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
521 PM MDT Sun Aug 14 2022 .AVIATION... 00Z TAF CYCLE Upper high center over the TX Panhandle. Sct showers and tstms over wrn NM with isold cells over nw and north central NM at 23Z to diminish aft 03Z. Brief mt obscurations and heavy rain along with gusty outflow winds associated with the stronger storms. With the upper high shifting slightly swd by 15/21Z, convection to become sct over wrn and nrn NM as cells move more to the ne. && .PREV DISCUSSION...240 PM MDT Sun Aug 14 2022... .SYNOPSIS... The relative break in the monsoon action that we`ve been experiencing over the past several days will come to an end as we transition into a new week. As monsoonal moisture returns to New Mexico and a backdoor front arrives, this will allow for the increase in storm coverage areawide, especially starting Tuesday and Wednesday. This also means that the threat for heavy rainfall and flash flooding ramps back up, especially on the northern burn scars which have largely been spared over the past several days. With the increasing moisture and storm coverage, also look for temperatures to trend cooler this upcoming week. && .DISCUSSION... SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT)... Afternoon convection is slightly farther east than forecast with storms firing as far east as eastern Cibola county. Despite the dry upper levels, enough low level moisture in the RGV to combine with a mid-level moisture gradient, helping to destabilize things further, to result in scattered convection. Showers and storms are forecast to dissipate shortly after sunset. Main change to the short-term forecast was to lower precipitation chances for portions of the middle RGV Monday afternoon. NBM PoPs are quite overcooked when compared with other trustworthy hi-res models including the HREF, HRRR and NAM. Monsoon high (centroid over the Southern Plains) is forecast to sag southwestward to near Tucumcari by midday Monday. South and southwest winds aloft are forecast to strengthen somewhat, helping to pull up mid level monsoon moisture from far southwest NM and into the RGV as well as over the crest of the central mountain chain Monday. Models continue with the idea that a relatively robust backdoor front will drop into northeast NM Monday night. This front is expected to result in nocturnal convection over the northern quarter or so of the state Monday night. Overnight heavy rainfall is a possibility for the HPCC burn scar Monday night due to the front. Storm motion for thunderstorms over the Sangre de Cristo mountains Monday night will be to the northeast around 15 mph. 33 LONG TERM...(TUESDAY THROUGH SUNDAY)... By Tuesday, the main H5 high is centered near the Four Corners area while a secondary high is centered over west TX. Meanwhile, an easterly wave tracks westward along the International Border, blocked from any northward progress by the TX high. The presence of this high and drier air will likely lead to a downtrend in storm coverage across the south on Tuesday. The best monsoonal moisture will reside across northern NM (aided by the arrival of a backdoor front) which will likely be the hot spot for thunderstorm coverage, increasing the flash flooding risk in areas that have largely been spared for several days, including the HPCC burn scar. The backdoor front makes progress Tuesday night potentially all the way to the AZ border, which may generate a moderate east canyon wind in Tijeras Canyon and on the east side of ABQ Tuesday night and into Wednesday morning. That easterly wave along NM`s southern border stays within that area, but moisture advection behind the front will be more than enough to see an uptick in storm coverage areawide Wednesday and Thursday with the greatest coverage across the north which should benefit from upslope flow as well. Model differences exist in the late week period and into next weekend as a closed low dives southward into the Midwest while another disturbance perhaps tracks into the western CONUS. The H5 high which is squeezed between these features perhaps becomes more amplified over the Rockies, but despite this, the monsoonal moisture looks to remain in place across New Mexico. A very active pattern continues. 15 && .FIRE WEATHER... Despite the drier weather for much of central and eastern NM over the past couple of days, the monsoon remains in full swing with no critical fire weather condtions expected during the next 7 days. A backdoor cold front is forecast to ramp up thunderstorm activity for much of the forecast area Tuesday, continuing through the remainder of the work week. 33 && .ABQ WATCHES/WARNINGS/ADVISORIES... Flood Watch until 10 PM MDT this evening for the following zones... NMZ208. && $$
Area Forecast Discussion
National Weather Service Cheyenne WY
525 PM MDT Sun Aug 14 2022 .SHORT TERM...(This evening through Tuesday night) Issued at 220 PM MDT Sun Aug 14 2022 Forecast concerns with this afternoon package deal with heavy rain chances this afternoon through Monday. Currently...Upper ridge axis positioned near the Nebraska/Wyoming state line this afternoon. Layered PWATs from GFS showing 1.5 inches along and east of the Laramie Range...with near 1 inch west. Advertised upper shortwave now located in southwestern Wyoming...moving east northeast out of northern Utah from this morning. Convection on radar beginning to blossom across southern Albany and southeastern Carbon Counties...as well as north central Colorado. Storms are moving a lot more than yesterday...so that may be a good thing for this afternoon. Severe storms still a possibility this afternoon as SB CAPE climbs to 1500 to 2000J/Kg. Southern Panhandle showing slightly higher CAPE near 3000J/Kg. Very little in the way of shear though and with long/skinny CAPE profiles...still think the primary hazards will be heavy rain and flash flood potential. HRRR and RAP13 simulated radar shows convection becoming widespread around 23Z across Laramie and southern Albany Counties...shifting northeast into Platte and Goshen Counties around 01Z. Probably the best area for severe storms will be the central and southern panhandle with those higher CAPES forecast. This mesoscale guidance keeps storms going well into the evening hours in the Panhandle...not clearing our eastern CWA until after 07Z tonight. Upper shortwave finally moves east into western South Dakota after 15Z Monday with trough axis clearing the Panhandle after roughly 21Z Monday.See a substantial decrease in PWATS behind the shortwave...with .5 inch west of the Laramie Range and 1 inch in the Panhandle. Given possibility of widespread rainfall tonight and recycling of this moisture for Monday...still kept fairly high PoPs for Monday afternoon. Much drier Tuesday afternoon as monsoonal moisture gets forced south into Colorado through the morning hours. Would think most areas will be dry Tuesday afternoon. .LONG TERM...(Wednesday through Sunday) Issued at 220 PM MDT Sun Aug 14 2022 Long term forecast remains on track through the end of the week. The plume of monsoonal moisture starts to break down across the area Monday night as the upper-level ridge sitting over the High Plains begins to broaden and shift further west. As a result, PWATs across the CWA drop down to about climatological normal with minimal storm chances expected through Thursday. Cannot rule out daily isolated thunderstorms during the afternoon hours as subtle disturbances within the ridge may trigger some development. However, storms should mainly stick to the high terrain and immediate adjacent plains. Another result of this pattern change are cooler temperatures. Many places across the CWA will see their temperatures drop to normal or even slightly below normal for this time of year. For the most part, high will be in the 70s and 80s through the end of the week. Things could get interesting again next weekend with the potential for another surge of monsoon moisture. Both the GFS and ECMWF have a similar set-up, but differ on where the better moisture sets up. GFS has the moisture plume west of the CWA due to an upper-level low sitting over the South Dakota/Iowa border. ECMWF puts the moisture plume over the western part of the CWA as it places this low further east over the Great Lakes. Fortunately, there is still plenty of time for the models to iron out a solution for next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 521 PM MDT Sun Aug 14 2022 Wyoming TAFS...VFR, except for occasional MVFR and wind gusts to 30 knots in thunderstorms until 02Z at Laramie and Cheyenne. Thunderstorms in the vicinity and wind gusts to 25 knots at Rawlins until 02Z. Wind gusts to 25 knots at Cheyenne after 15Z Monday. Nebraska TAFS...VFR, except for MVFR and wind gusts to 30 knots in thunderstorms until 06Z, and IFR at Chadron and Alliance from 09Z to 15Z. && .FIRE WEATHER... Issued at 220 PM MDT Sun Aug 14 2022 Monsoon moisture in place through Monday will keep fire weather concerns at bay. Good chances for showers...storms and wetting rains. Begin to dry out from north to south Monday with monsoon moisture getting forced south...as upper high pressure builds across western and central Wyoming. Afternoon humidity stays above critical levels through Wednesday before we begin to flirt at critical afternoon humidity Thursday. && .HYDROLOGY... Issued at 221 AM MDT Sun Aug 14 2022 Plentiful monsoonal moisture will continue to impact the CWA through Monday. Ensemble members prog precipitable water values between 1" and 1.5" along and east of the Laramie Range today and tonight, and western Nebraska Monday. Showers and thunderstorms will continue to be efficient rain producers. 0.5-0.75" in 30-45 minutes over the Mullen burn scar may result in flash flooding and debris flows. Excessive rainfall Saturday afternoon in Laramie caused flash flooding, with the Laramie River at Laramie rising 4 feet in less than an hour. Heavy rain over and upstream may result in additional rises this afternoon and evening. The Areal Flood Watch remains in effect through late Sunday evening. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Flood Watch until midnight MDT tonight for WYZ103>107-109>118. NE...None. && $$ SHORT TERM...GCC LONG TERM...SF AVIATION...RUBIN FIRE WEATHER...GCC HYDROLOGY...MJ
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
945 PM CDT Sun Aug 14 2022 ...New UPDATE... .UPDATE... Issued at 931 PM CDT Sun Aug 14 2022 The surface low is now located just south of Laredo and moving slowly west. Mesoanalysis reveals strengthening low level winds along the Mid Texas Coast and an area of increasing deep layer moisture flux convergence has developed in this region. An intense band of convection has developed from Aransas County inland into Bee and Goliad Counties. The latest HRRR runs have picked up on this and are moving this band northwest into portions of Karnes, Atascosa, and Wilson Counties over the next 1-3 hours where favorable thermodynamic profiles still reside. Overnight, as the low drifts into Mexico, the HRRR suggests additional strengthening of bands into portions of the Winter Garden region (Frio, Zavala, and Dimmit Counties), before potentially expanding up the Rio Grande into Maverick, Kinney, and Val Verde Counties Monday morning. There is the potential for some locally heavy rainfall across these areas of the CWA overnight and Monday. The most immediate concern will be Karnes and Atascosa Counties, where WPC has recently highlighted this area for the potential for some rainfall rates up to 3" per hour should the heavier band making it this far inland. && .SHORT TERM... (Tonight through Monday night) Issued at 239 PM CDT Sun Aug 14 2022 The upper air pattern across the U.S. shows a large upper level ridge over the Rockies and Central/Northern Plains while a fairly deep upper trough is over the NE United States. The low pressure area that was over the western Gulf yesterday and overnight has moved ashore in south Texas and the surface observations and radar show the circulation center near Alice. Because of the counter clockwise flow around this system, deep 2+ inch PW moisture has moved into South Central Texas. A few bands of showers and isolated storms have been moving west during the day today giving some folks some brief heavy downpours. Most rain totals so far have been a 1/4 inch or less although a few totals are approaching 0.50 inches. Much heavier convection and significant banding is occurring off the BRO/CRP coast. This is creating a fairly large mid and high level cloud deck which has helped to keep afternoon temps down several degrees especially over the southern CWA. Out west near DRT has been the only area that has been in full sun today, and thus has the warmest temps. Have lowered temps already across the north and east for the rest of the afternoon, but might have to do it one more time based on the latest metars. As the sun goes down, most of the convection will decrease across our cwa. CAMs show little to no POP across the northern half of the cwa overnight. However, with some night time development likely closer to the circulation overnight, keeping chance pop (30-50 percent) basically along and south of Highway 90...to include the SAT area. QPF overnight could be in that 0.25-0.50 inch range across the far southern areas into the Rio Grande Plains. Clouds should be fairly prevalent overnight into Monday morning with lows in the 70s. The highest pop follows the low pressure area as it heads west into Mexico by Monday morning. As we see with many lows that head into northern Mexico this time of year, it will likely pull moisture up the Rio Grande and result in some scattered to numerous SH/TS over our SW zones and along the Rio Grande...into Monday night. QPF on Monday from Eagle Pass up to DRT could result in rains over 1 inch...isolated higher totals due to the high PW values over 2 inches. Not out the question that some spots could easily see a couple inches of much needed rainfall. Monday will see temps rebound especially over the north where POP will remain very low and more sun is expected. && .LONG TERM... (Tuesday through Sunday) Issued at 239 PM CDT Sun Aug 14 2022 The long term begins as the remnants of what was Invest 98-L vacate to West Texas and northern Mexico. A high-amplitude synoptic pattern will prevail in its wake, with mean troughing across the eastern half of the CONUS and well-defined ridging in the Mountain West. Both features should become most pronounced by the Wednesday- Thursday timeframe as a closed mid-level low develops over the northeastern US. Stuck between the two features locally, winds will become predominantly northwesterly in the 700-300 mb layer as this occurs, helping to drive a surface cold front into the state through early Thursday morning. Said boundary will begin to return north as a warm front from Friday afternoon through next weekend. With the early week inverted trough continuing to distance itself from the region, expectation is that the vast majority of the measurable rainfall will have concluded by the beginning of the period. Have thus gone with a largely dry forecast across most of the area on Tuesday, with the exception of the Rio Grande Plains where straggling isolated to scattered convection could hold on through the afternoon hours. Don`t anticipate much in the way of additional accumulation, but any activity could produce an additional several hundredths to one tenth of an inch of new rainfall on top of the totals seen through the conclusion of the short term. Given this potential, anticipate that the coolest high temperatures will be found along the Rio Grande Tuesday afternoon, where readings in the low 90s are likely. This will be in stark contrast to areas along and east of the I-35 corridor, where dry conditions and a lack of residual cloud cover should allow temps to top out in the upper 90s to low 100s. Wednesday should be the driest and warmest day of the forecast period, particularly in spots along the I-35 corridor and within the Coastal Plains. Widespread high temperatures in the 99-103 range, along with heat index values spanning from 103 to 108, could create potentially hazardous conditions for those planning to spend prolonged periods of time outdoors across this portion of the CWA. Will continue to monitor trends for any potential heat headlines that may become necessary. Expect slightly lower temps and heat indices across the southern Edwards Plateau where greater cloud cover will be in place. The southernmost progress of the cold front mentioned above continues to be a source of uncertainty as of this forecast package. Progs continue to point to the possibility of the boundary reaching the Edwards Plateau prior to stalling out during the day on Thursday. Regardless of where it ultimately ends up, the front should be in close enough proximity to the region to trigger scattered showers and thunderstorms by the afternoon hours on Thursday. Chances should continue on Friday, with activity being strongly influenced by daytime heating. While too early to speak to precise QPF amounts, heavy downpours could bring pockets of beneficial rainfall to portions of the region. Isolated storm chances will continue through next weekend as the front returns north from the area. && .AVIATION... (00Z TAFS) Issued at 621 PM CDT Sun Aug 14 2022 At 23Z the surface low was located roughly between LRD and HBV. The low will continue W tonight and then more NW in Mexico Monday. A decrease in coverage of SHRA away from the center of the low is expected initially after sunset. Guidance then suggests nocturnal expansion in coverage 06Z-12Z SW of SAT and just S of DRT. Latest HRRR runs indicate the precipitation expanding into DRT after 12Z and continuing into the early afternoon. A few SHRAs could potentially be in the vicinity of SAT/SSF as well. There is a high degree of confidence that MVFR ceilings will also develop overnight and into Monday morning along and west of a AQO-SAT-PEZ line, with a potential for pockets of IFR ceilings, especially in precipitation SW of SAT to the Rio Grande. Confidence is lower in the MVFR ceilings into AUS, but for now we have included this in their TAF. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 75 97 75 102 / 10 10 0 0 Austin Bergstrom Intl Airport 75 97 73 101 / 10 10 0 0 New Braunfels Muni Airport 75 97 73 99 / 20 20 0 10 Burnet Muni Airport 74 96 75 100 / 0 10 0 0 Del Rio Intl Airport 77 87 76 93 / 30 70 50 40 Georgetown Muni Airport 75 99 76 101 / 0 10 0 0 Hondo Muni Airport 75 92 74 97 / 40 50 10 10 San Marcos Muni Airport 73 97 73 99 / 20 20 0 10 La Grange - Fayette Regional 74 98 74 99 / 10 10 0 10 San Antonio Intl Airport 76 93 75 98 / 30 40 10 10 Stinson Muni Airport 76 94 76 99 / 40 40 10 10 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...09 Long-Term...Quigley Aviation...76
Area Forecast Discussion
National Weather Service Flagstaff AZ
737 PM MST Sun Aug 14 2022 .SYNOPSIS...An active monsoonal pattern will continue across northern and central Arizona through the upcoming week. Heavy rainfall leading to flash flooding will continue to remain a threat as a result. As a reminder, be sure to avoid flood prone areas. If you come across flooded roadways...make the smart choice and turn around, don`t drown. && .UPDATE...Things have calmed quite a bit from earlier today, however, there are still Flash Flood Warnings out there in some areas. Rainfall continues, as well, with the threat of nighttime flooding a harsh reality again tonight. Do not enter floodwaters! && .PREV DISCUSSION /112 PM MST/...Today and tonight...Showers and thunderstorms have developed across much of the high terrain this afternoon. RAP Mesoanalysis shows the greatest PWAT and MLCAPE values over west-central Arizona, as earlier cloud cover from a decaying MCV has limited instability over the eastern Mogollon Rim. Storms are expected to continue to increase in coverage through the remainder of the afternoon into this evening. Deep monsoonal moisture (PWATs around 1-1.5") and slow storm motions (~5 kts) this afternoon will result in flash flooding being the primary hazard with these storms, especially over flood prone areas (recent burn scars, slot canyons, and low-water crossings). However, small hail and gusty winds can not be ruled out with any of the stronger thunderstorms. Coverage and intensity should begin to decrease after sunset with the loss of daytime heating. Hi-Res guidance does point towards lingering stratiform rain with embedded heavier downpours developing into another MCV overnight across northwestern Arizona late this evening. Overnight impacts from this system should be minimal. Any remaining showers and cloud cover Monday morning may result in delayed or hampered convection during the afternoon. Monday through Wednesday...Monsoonal moisture gradually begins to lessen slightly each day over the High Country through mid-week. Daily shower and thunderstorm chances are expected to remain, though with slightly decreased coverage each day. Nevertheless, flash flooding will remain a concern with areas of heavy rainfall. Thursday through next weekend...A disturbance over the western Gulf of Mexico tracks westward through northern Mexico through the upcoming week. As it draws closer, passing over Sonora, deep monsoonal moisture is pushed northward into Arizona. Ensemble mean PWAT values from the GEFS and EPS show around 1.5-2" across the lower deserts of Arizona with 1-1.5" across the High Country. As a result, an active period in the monsoon, and thus an increased flash flood risk, look to return for the later half of next week. && AVIATION...For the 06Z TAF package...Isolated shower and storm activity becoming more widespread Monday after 18Z. Gusty and erratic winds and MVFR/IFR conditions in and around storms with light winds/VFR away from storms. Aviation discussion not updated for TAF amendments. && FIRE WEATHER...Widespread showers and storms will continue through Tuesday with peak activity in the afternoons. Expect gusty and erratic winds near any storms. Flash flooding remains possible. Otherwise, light winds away from storms with little change in high and low temperatures. Tuesday through Thursday...Little change. Monsoon moisture will remain in place with showers and thunderstorms each day. && && .FGZ WATCHES/WARNINGS/ADVISORIES... Flood Watch until 11 PM MST this evening for AZZ004-006>008- 015>018-037-038-104-106>108-115>118-137-138. && $$ PUBLIC...Kobold/Humphreys AVIATION...Kobold FIRE WEATHER...McCollum For Northern Arizona weather information visit weather.gov/flagstaff
Area Forecast Discussion
National Weather Service Lake Charles LA
1014 PM CDT Sun Aug 14 2022 .UPDATE... The isolated convection that developed through the afternoon dissipated early this evening. As has been the case the last couple of nights, trapped low level moisture below a dry mid layer may allow for some low cloud or patchy fog development near sunrise. However, this isn`t expected to be widespread enough to warrant explicit mention in the forecast as of now. Upper level ridging will continue to build back across the region Monday which, combined with the drier mid level air, will keep a lid on convection although a few isolated storms will be possible during max heating through the afternoon. The lower cloud cover will allow afternoon highs to climb into the low to mid 90s along the I-10 corridor with upper 90s expected across interior southeast Texas and central Louisiana. The inherited forecast is in good shape and no significant changes were required. Jones && .PREV DISCUSSION... /issued 545 PM CDT Sun Aug 14 2022/ DISCUSSION... For the 08/15/2022 0000 UTC TAF package. AVIATION... Radar only showing a couple of showers, none near the terminals. Not expecting any significant precipitation this evening, and less than 20% for Monday. Southerly winds around 8-10 kts now expected to become variable at 5 kts or less this evening and overnight. May see intermittent MVFR visibility from 09-13z at AEX, otherwise, VFR expected. 08 PREV DISCUSSION... /issued 401 PM CDT Sun Aug 14 2022/ SYNOPSIS... The latest WV imagery and UA analysis shows upper ridging beginning to build back over the area in the wake of the low pressure system that is now just inland of the TX coast south of CRP. In addition, some drier air is attempting to infiltrate the region, but this has not been enough to overcome moisture/instability in the lower levels, with KLCH radar showing what has mostly been some scattered showers across SE TX into W LA, and more isolated convection across SW/S central LA. Surface analysis shows high pressure has resumed across the northern Gulf coast, yielding a modest onshore flow over the area. With cloud and shower coverage a little less than the last several days, temperatures have warmed to around 90 across the southern zones with lower 90s across interior SE TX into central LA. 24 SHORT TERM [Tonight through Tuesday Night]... Minimal changes to the forecast for the next few days as ridging aloft remains over the region, and surface high pressure prevails across the northern Gulf. Precipitable water values are expected to continue falling through Monday, possibly as low as 1.3-1.4 inches across portions of the area per NAM12 and HRRR PWAT progs. This should help to inhibit convection across the area on Monday, with the best, albeit low, chances for any showers or storms across S central LA during the afternoon. By Tuesday, slightly better moisture will begin to expand across SE LA into central and S central LA, and with it, a slight uptick in PoPs across these areas. Despite this, convective coverage should 66 && .DISCUSSION...stay isolated to widely scattered, and mainly east of a Leesville to Lake Charles line. As heights build aloft and cloud and shower coverage decrease, daytime temperatures are expected to climb back to above normal. High temps are expected to range from the lower 90s across the southern zones to the upper 90s/near 100 across the northern zones, with Tuesday a little warmer than Monday. Slightly drier air mixing down during the day will yield dewpoints in the upper 60s to lower/middle 70s, resulting in max heat index values between 100 and 108 degrees. At this time, do not anticipate issuance of any heat advisories for the area, although a few isolated spots across central LA or the Lakes region of SE TX could reach criteria for an hour or two either afternoon. 24 LONG TERM [Wednesday through Sunday]... Global models continue to be in good agreement for the long range period, showing the break down of deep layer ridging by mid week via shortwave energy digging through the Plains/Mid MS River Valley. Rain chances will start to increase on WED, but are still progged at just below seasonal normals while highs are forecast to remain quite warm, reaching into the mid/upper 90s and near triple digits across interior SE TX into Central LA, with more seasonal lower to mid 90s along the I-10 corridor. A more robust upstream trof is forecast to dig into the Central CONUS THU and FRI, nudging a weak frontal boundary to our doorstep or perhaps just far enough to sneak into northern zones, where it is progged to meander until retreating back north and/or washing out on SAT. Copious MSTR pooled along/south of the boundary coupled with perturbations translating through the W/NW flow aloft will yield multiple periods of widespread showers and thunderstorms THU and FRI. The trof is progged to lift out on SAT, and the resulting weak ridging along with the intrusion of some relatively drier air will start to bring rain chances back down for the weekend. 13 MARINE... Surface high pressure will continue to ridge across the northern Gulf of Mexico through the week. This will produce a mainly light onshore flow, along with low seas, for the next several days. Rain chances will remain limited until late in the week when a surface front is expected to move south into the area. 24 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...None. TX...None. GM...None. && $$
Area Forecast Discussion
National Weather Service New Orleans LA
700 PM CDT Sun Aug 14 2022 ...EVENING UPDATE... Performed a brief gridded update this evening to reflect radar/short-range guidance thru tonight and into early Monday. Few decaying showers around the Southshore and over coastal MS/AL caused by earlier outflow/seabreeze boundary interactions will continue to dissipate thru sunset. Did add small isolated coverage in these areas, but we`ll clear out nicely going into tonight. No major changes in the thinking for Monday with continued less overall afternoon shower/storm coverage thanks to slightly drier air in the profile aloft. Focus for shower (and some storm) coverage Monday will be primarily along lake/seabreeze boundaries and where they intersect with remnant outflow boundaries from showers so generally hit-or-miss and limited in coverage. Not seeing any distinct severe weather parameters jumping out per latest HRRR soundings, but a slight uptick in the low to mid-level dry air could help with entrainment in any rogue stronger updraft to deliver brief, gusty downdraft winds in excess of 30 to 40 mph but will not be a widespread issue. Additionally, did notice short-range guidance hinting at convective development across central AL/GA in response to a southward drifting cold front, which becomes deep enough to ride the SSE mean flow into the northern Gulf. Consensus along HREF members are to keep this potential activity east of our area, but will have to watch subsequent CAM runs if it can clip parts of coastal MS Monday evening but, not including that risk in the forecast for now. KLG && PREV DISCUSSION... /issued 359 PM CDT Sun Aug 14 2022/ SHORT TERM... Not really much in the way of anything unexpected across the area today. Weak ridging over the area has brought in slightly drier air and kept rain coverage down for the most part today. Model sounding PW values are down below 1.9 inches across most of the area. While that normally would not sound all that impressive, given the events of the last few weeks, we will take it. Any shower activity should begin to wane as the afternoon and evening progresses. As we begin the new work week, rain chances will continue on the lower side, especially compared to the recent norms as ridging tries to hold in place. Lower rain chances does mean temperatures will rise into the lower 90s in most locations with enough moisture still around to make heat index values noticeable. Generally should see values in the 102-106 range tomorrow and Tuesday which keeps us below heat advisory criteria. LONG TERM... By mid-week a series of disturbances riding across the central Plains and with riding sliding east over Florida and the Atlantic, will allow for a slight increase in rain chances. That said, the front will not likely make much headway towards our area Wednesday and will allow for at least one more day of more typical summer rain chances. As the boundary shifts slightly south and disturbances make their way closer to the forecast area, rain chances are likely to be on the rise again by Thursday and Friday as well as the weekend. Did not stray much from the NBM with rain chances increasing again after Wednesday. AVIATION (00Z TAF DISCUSSION)... Only activity on radar this evening remains to be a few isolated showers in the vicinity of MSY, but will dissipate by 01-02Z this evening. Otherwise, expect VFR flight conditions overnight tonight into early Monday for all area terminals. Can`t rule out some light ground fog in and around KMCB between 11-12Z, but chances will be lower than previous days and not anticipating widespread dense fog or impacts to follow. KLG MARINE... A weak frontal boundary will continue to move closer to our region before stalling and eventually dissipating early in the week. This feature will likely weaken pressure gradient just enough to help provide overall favorable marine conditions. That said, diurnally driven convection will still be possible...albeit a bit more limited in terms of coverage. Still cannot rule out locally higher winds and seas with the stronger showers and storms, but, it`ll probably be about Wednesday before areal coverage of storms gets anywhere near as widespread as the past week. 35 && .PRELIMINARY POINT TEMPS/POPS... MCB 72 93 73 93 / 10 30 10 40 BTR 74 94 75 95 / 10 30 10 40 ASD 75 94 75 94 / 10 30 10 40 MSY 77 93 77 92 / 10 30 10 40 GPT 76 93 76 93 / 20 40 20 40 PQL 75 93 75 93 / 20 40 20 40 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$
Area Forecast Discussion
National Weather Service Las Vegas NV
147 PM PDT Sun Aug 14 2022 .SYNOPSIS...Flash Flood Watch continues today for scattered thunderstorm activity in southern Nevada and northwestern Arizona. Anomalous moisture in place continues to aid thunderstorms in producing heavy rainfall and widespread flash flooding, particularly in areas of higher terrain. Thunderstorm chances persist each afternoon through the forecast period, with best chances late-week as we gear up for a possible tropical influence. && .DISCUSSION...Today through the week. Anomalous moisture persists for the Desert Southwest, with over an inch and a half of PWAT in the 12Z Las Vegas sounding. Yesterday, convection was slow to start, and experienced a bit of inhibition due to early-morning cloud cover across the region. This morning, skies cleared early, allowing the surface to sufficiently heat, with the first Flash Flood Warning issuance of the day at 12:27pm PDT. As expected, isolated thunderstorms with frequent lightning and locally heavy rainfall favored the high terrain so far this afternoon, but as valleys reach their convective temperatures, we expect areal coverage to greatly increase through the afternoon. There remain a number of vulnerable locations across our forecast area due to repetitive monsoonal flooding. The majority of roads through Death Valley National Park remain closed due to flood damage. The Mojave National Preserve was able to open the majority of theirs on Friday, but North Kelbaker Road and Zzyzx Road remain closed. Golden Valley and Kingman have had numerous flood events so far this season as well, with widespread flood and heavy rain impacts observed yesterday. Due to heavy rainfall continuing to target similar areas each day, soil moisture content has increased, which provides antecedent conditions prime for additional flash flooding. In general, isolated thunderstorm activity will wane after sunset. However, models, including the 18Z run of the HRRR continue to hint at a northeasterly storm prorogation tonight from southwestern Utah through Lincoln, then northern Mohave and eastern Clark counties between sunset and midnight. This storm direction is favorable for heavy rain in the Las Vegas Valley. Confidence is low at this time in it coming to fruition... hi-resolution models have hinted at similar set ups each evening over the last few days, with minimal-to- no experienced impacts. That said, the signal for a northeasterly event returns Monday night, but there are a number of questions about how Monday convection will materialize, in general. Ongoing convection overnight tonight has the potential to keep the area socked in with cloud cover Monday morning. WPC has shifted their SLIGHT risk eastward, and out of our forecast area entirely for Monday... a solution that the HREF 3 hour PMM supports. With no clear forcing signal and in coordination with our neighbors, opted out of extending the Flash Flood Watch into Monday at this time. The 18Z HRRR shows +40 dBZ convection across northern Inyo, Esmeralda, and central Nye counties Monday, but due to PWAT regression, these storms are not as likely to produce the same magnitude of rainfall that we have experienced the last few days across the Mojave Desert. Confidence will increase either for or against a Monday watch tonight with the 00Z HREF run, but at the moment, WPC, HREF, nor NBM are enthused with rain totals tomorrow. An area of high pressure will build over northeastern Nevada and southern Utah tomorrow... a pattern that often results in vorticity ejections southwestward through Clark County, producing heavy rain in the Las Vegas Valley. Stay tuned as we work to resolve some of the finer details of the forecast. Regardless, we`re in the midst of an active monsoon with anomalous PWATs stretched across the Desert Southwest. Mountain zones can expect daily afternoon thunderstorms with greatest chances the further east you move through our CWA - additionally, any areas along outflows from the previous day`s MCS activity. Late week, a potential tropical influence may work to drastically increase PoPs and QPF across our forecast area. According to the NHC, the disturbance in question is currently positioned over Corpus Christi, where 12Z soundings read over 2.5 inches of PWAT. This system is expected to move westward across northern Mexico this week, which could influence late-week monsoon activity across the Desert Southwest. && .AVIATION...For Harry Reid...Light winds this afternoon, generally favoring an easterly direction. Speeds around 5-8 knots. Thunderstorm development expected this afternoon on the mountains south and west of the valley. These could send outflow winds to the terminal, but the prospect of storms in the valley appears to be fairly low at the moment. Winds should turn southerly in the late afternoon and evening, with speeds around 8-10 knots. There is a low possibility of northeasterly outflow winds, and potentially storms, reaching the valley this evening, but confidence is not high enough to include in the TAF at this time. Otherwise, expect light southwest winds overnight, turning to the east tomorrow morning. SCT-BKN mid and upper-level clouds throughout the TAF period. For the rest of southern Nevada, northwest Arizona and southeast California...Light winds expected across the area with scattered mid and upper-level clouds. Afternoon thunderstorms are expected to develop in the vicinity of the Las Vegas Valley and Colorado River Valley sites. Outflow winds, and possibly TSRA, could impact these airports, with the best chances at KHND, KIFP, and KEED. Thunderstorm activity is expected to wane in the evening, though there is a low possibility of storms/outflow moving southwest into the Las Vegas Valley this evening. There remains a fair amount of uncertainty in this scenario, thus opted to not include in the respective TAFs. Should confidence increase, amendments will be needed. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ DISCUSSION...Varian AVIATION...Woods For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter