Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/25/21

Area Forecast Discussion
National Weather Service Cleveland OH
943 PM EDT Sat Jul 24 2021 .SYNOPSIS... A warm front will move eastward across northwest Pennsylvania late this afternoon. A cold front is expected to sweep across the region on Sunday. High pressure will increase its influence on the region from the west Sunday night with the high located over Ohio by Monday night. The next cold front crosses the region on Wednesday. && .NEAR TERM /THROUGH SUNDAY NIGHT/... 930 pm update... We made some minor adjustments to the hourly pop chances during the late evening and overnight time frame to better reflect the latest radar trends and HRRR guidance with convection across southern Michigan heading our way. The broken line of convection will start to enter in our NW Ohio area around 2z and closer to the lakeshore by 3z to 4z and south of the lakeshore and Ohio Turnpike by 5z or 6z. The will be gradual weakening trend by 6z. Previous discussion... Warm front continues to move eastward across NW PA taking the remaining showers with it. Our attention will then shift to Michigan where a cold front will assist with the initiation of thunderstorms through the evening. A few of these storms during the evening could drift across NW OH and maybe cross Lake Erie with some stronger wind gusts. For the most part it looks like the storms will be decreasing in intensity as they cross the region late this evening into the overnight. However we will need to monitor closely. Brief heavy rainfall will accompany the the thunderstorms that move southward through the morning. Fortunately these storms should have a good forward speed so the threat of flooding is low. There should be enough breaks in the cloud cover this afternoon to allow highs to reach the mid 80`s across the central and western CWA. It will definitely feel much more humid into the overnight. Lows tonight will be on the warm side with upper 60`s to lower 70`s common. Outflow from the thunderstorms should move southward across the CWA through the morning hours and should become the primary focus for thunderstorms through the afternoon. So for now the thinking is that most locations will be dry by mid afternoon. One thing for us to monitor will be the actual cold front that will lag its southward movement slightly. This boundary could generate a few showers late afternoon into the early evening across the southeastern half of the CWA. COnfidence is not high in this potential but it is something for later shifts to monitor. Highs on Sunday look to be in the 80`s for most locations. High pressure is expected to increase its influence on the region Sunday night. Clearing skies, light winds and recent rainfall may allow for fog formation early Monday morning. Lows will range from the lower 60`s across inland NW PA to near 70 along the lakeshore. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... By Monday morning, west to northwest flow aloft will be entrenched across northern Ohio and northwest Pennsylvania. Precipitable water values will range from 0.8 to 1 inch across the forecaster area and deeper moisture will be displaced south from Mid Mississippi Valley to Mid Atlantic state line early Monday. Surface high is expected to be positioned over central Illinois on Monday. Expecting dry conditions with temps slightly above norms for lows and highs Monday and early Tuesday. Upper level ridge over the plains is expected to build and amplify yielding a more northwest flow across the Great Lake region. Euro and GFS are showing a wave diving southeast from Lake Superior to Lake Ontario late Tuesday. This feature may yield a few showers and isolated thunderstorms across the forecast Tuesday afternoon and Tuesday night. Surface base capes of 1500 to 2000 j/kg Tuesday afternoon and 800 to 1000 j/kg Tuesday night may be in play. Precipitable water values are expected to rebound to 1.25 to 1.5 by Tuesday afternoon. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Lingering showers and a few storms are possible across the central Ohio Wednesday morning. The synoptic pattern will remain in place through the week with the ridge building over the Plains. This will allow the trough remain over the northeast and northwest flow over the forecast area through week. Precipitable water values will decrease with the passage of the wave Tuesday night...expecting values to drop to slightly below 1 inch Wednesday afternoon and rebound Wednesday evening. As a result, moisture will increase from west to east Wednesday night into Thursday. A stronger wave is expected dive southeast and track across the forecast area Thursday morning. A possible thunderstorm complex is possible associated with this wave. There is still a great deal of uncertainty with the placement of the initial convection on Thursday. Will maintain rain chance with thunderstorms for Thursday and linger into Friday. High temperatures for this period will begin in the mid to upper 80s on Wednesday and a slight cool down to the low to mid 80s by Friday. Overnight lows will also follow a gradually cooling trend, beginning in the mid to upper 60s on Wednesday night to the low to mid 60s on Thursday night into Friday morning. && .AVIATION /00Z Sunday THROUGH Thursday/... Generally VFR ceilings this evening will transition to MVFR ceilings with a broken line of showers and storms associated with a cold front moving through the region overnight. MVFR ceilings will linger through much of Sunday morning with a improvement back to VFR conditions around midday Sunday through the afternoon. TEMPO have been timed accordingly for each TAF site with a 2 hour window for the likely impacts of lower visibilities and ceilings with the heavier downpours. It appears this convection will be on the weakening trend as it starts to move into local area overnight. Southwest winds this evening around 5 to 10 knots will gradually become westerly overnight initially with the front passage. Winds on Sunday will become northwest around 5 to 10 knots. Outlook...Non-VFR possible in fog Monday morning. Non-VFR also possible in showers/thunderstorms Tuesday night into Wednesday. && .MARINE... Southwest winds of 10-15 knots as the warm front moves across the lake this evening. Waves should remain between 1-3 feet. A cold front will move east across Lake Erie on Sunday. This will yield a wind shift to east to northeast or 5-10 knots. High pressure will build across the lake behind the frontal passage which will allow calm conditions across the lake to persist through mid-week. Due to the relaxed pressure gradient flow, a wind shift is expected along the lakeshore associated with a lake breeze during the afternoons. No marine headlines are expected at this time. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...None. PA...None. MARINE...None. && $$ SYNOPSIS...MM NEAR TERM...Griffin/MM SHORT TERM...FZ LONG TERM...FZ AVIATION...Griffin MARINE...FZ
Area Forecast Discussion
National Weather Service Cheyenne WY
507 PM MDT Sat Jul 24 2021 .SHORT TERM...(Tonight - Sunday Night) Issued at 211 PM MDT Sat Jul 24 2021 Isolated to widely scattered showers & thunderstorms are currently developing across the higher terrain of southeast WY & the western NE Panhandle late this afternoon. Forecast soundings for KCYS/KSNY & SPC Mesoanalysis indicate strong capping & very weak instability along the I-80 corridor, suggesting it will be tough for showers & storms to be sustained as they move away from terrain features. Do not expect any severe storms today, but the higher probability for any stronger storms w/ small hail or gusty winds should be focused across east central WY into the northern Panhandle where up to 500 J/kg CAPEs were analyzed. Effective bulk shear of less than 20 kts should significantly limit updraft intensity. A similar pattern is expected to remain in place for Sunday w/ most convection expected to remain confined to the Laramie Range and/or the Pine Ridge. The overall threat for severe weather will be low. Trending warmer and drier as we head toward Monday. .LONG TERM...(Monday - Saturday) Issued at 315 AM MDT Sat Jul 24 2021 Good run-to-run model consistency with the large scale pattern next week. Model consensus favors a strengthening of the upper ridge center across the Central Rockies and High Plains early in the week. This position of the ridge will keep the monsoon plume confined to the south and west of the CWA. Large scale subsidence will limit convective development and produce afternoon temperatures in the lower 90s to lower 100s. The upper high center drifts slowly eastward Wednesday through Friday, opening the monsoonal moisture tap and increasing chances for mainly afternoon and evening showers and thunderstorms. Models continue to show a backdoor front pushing south and west into the CWA Thursday, with temperatures cooling closer to seasonal normals with highs in the 80s to around 90 Friday. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 455 PM MDT Sat Jul 24 2021 VFR conditions likely through the forecast period for all terminals. Current radar imagery indicates some showers and thunderstorms east of Lusk, with a east to southeasterly movement. Might see some light thunderstorm activity in the northern portion of the Nebraska Panhandle, with the potential for VCTS near KCDR. Otherwise, the extent of the forecast through early tomorrow morning has most terminals experiencing some wind gusts around 20 to 25 knots. Looking ahead over the next 24 hours, the HRRR has been fairly consistent with depicting cell locations and movement, and has some isolated to widely scattered showers & thunderstorms developing west of the Panhandle. Went ahead started trending terminals in southeastern Wyoming for VCSH beginning around 20z tomorrow. && .FIRE WEATHER... Issued at 215 AM MDT Sat Jul 24 2021 A weak surface front across northwest Nebraska and southeast Wyoming will slowly sink south into northern Colorado this morning. High temperatures this afternoon will be slightly cooler but still above normal for late July. The upper ridge of high pressure will be the dominating feature this weekend, suppressing the monsoonal plume of moisture to the south and west. Widely scattered mainly afternoon showers and thunderstorms are expected to develop, producing light rainfall and gusty winds. The ridge will strengthen over the region early next week, resulting in hot and dry weather. Minimum relative humidities will fall into the low and mid teens each afternoon, however wind speeds will be light. Shower and thunderstorm chances will increase mid to late next week with the return of monsoon moisture. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...CLH LONG TERM...MJ AVIATION...MD FIRE WEATHER...MJ
Area Forecast Discussion
National Weather Service Des Moines IA
613 PM CDT Sat Jul 24 2021 ...Updated for 00z Aviation Discussion... .DISCUSSION.../Tonight through Saturday/ Issued at 250 PM CDT Sat Jul 24 2021 Today and Tonight: Cloud cover throughout the late morning and early afternoon has resulted in some limitation of insolation today, which kept air temperatures a few degrees cooler. As noted overnight, moisture pooling ahead of the boundary kicked dewpoint temperatures up a few degrees, keeping heat index values above 100 across much of Iowa this afternoon. The trough that has provided some deamplification to the strong ridge and provided zonal flow across the Midwest is currently located north of the Great Lakes. The stronger vorticity with this trough remains well north of the area, but there have been subtle height falls over Iowa and throughout the northern Plains and upper Midwest regions. This was just enough to kickoff a weak surface low and thermal boundary, which has been setup across the eastern Dakotas and eastern Nebraska this afternoon. The parent short-wave well to the north will begin to lift this afternoon, but will drag the weak low pressure and boundary across Iowa this evening. There is a chance for convection initiation in southeast portions of the forecast area as this boundary approaches. RAP and HRRR soundings throughout this afternoon depict a considerable EML from about 850 to 750mb, with weak capping around 900 mb below the EML. Diurnal heating may be able to erode capping below the EML across southeast Iowa. If this ends up being the case and updrafts are able to develop from an air mass with dewpoints well into the 70s, precipitation loading would be favored in this environment. As a result, thunderstorms would have downburst potential, which could produce a few severe wind gusts. Late morning runs of the HRRR initiate convection around 00z in the far southeast portions of the area. By the time the boundary starts to produce stronger convergence in southeast Iowa, the deep-layer shear will be rather weak (25 kts at best) and thus difficult for convection to organize. The severe threat for damaging winds appears to be very small in coverage area, and will have a narrow window. The timing is playing out for a greater chance in Illinois and Missouri. The boundary passage will bring in drier air overnight, lowering dewpoints into the lower 60s. Rest of the Week: Sunday, dewpoints will be lower on the backside of the boundary, but the air temperatures will not be drastically cooler. With lower dewpoints, heat index values will be much less, and closer to the air temps on Sunday. The ridge begins to re-amplify over the western CONUS on Sunday, leaving the central Plains and upper Midwest downstream in northwest flow. This will likely put Iowa in favorable position for more smoke and haze in the skies from the western wildfires. If this ends up being a bit heavier in sky cover, temperatures may be a degree or two cooler. This ridge will dominate through most of the week across the central CONUS. Low-level flow will maintain a southerly component and keeps Iowa open to moisture from the Gulf of Mexico. Model consensus is strong for H5 heights to reach 597dam. This will keep weather conditions very hot and humid. Tuesday and Wednesday look to be the warmest days, and also the most hazardous with respect to heat. Wednesday, with air temperatures in the upper 90s, possibly up to 100 in some spots, and dewpoints well into the 70s, heat index values of 105 or maybe even higher can be achieved. Outdoor activities Tuesday and Wednesday will be difficult in these conditions. No precipitation is currently in the forecast through Wednesday, will just need to keep monitoring any localized sources of convergence though with this warm and moist of an atmosphere for an air mass thunderstorm. Synoptic support for any activity will not be strong. The ridge will remain over the Front Range toward the end of the week. There are a few signals in extended guidance for a short-wave perturbation to ride through the northwest flow downstream of the ridge, which introduces some precipitation chances by Thursday. Stronger short-wave perturbations then move through the northwest flow Friday into Saturday, which will present a better chance for precipitation and thunderstorms. But until Thursday, warm and humid will be the main story, with little rain. This will not be favorable for areas struggling with drought conditions. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 613 PM CDT Sat Jul 24 2021 A few storms have developed this afternoon from east of IKV to over GGI with another, slightly stronger line from just east of OTM to southeast of LWD. For the TAF sites, outside of the chance of lightning near OTM the next few hours and a too low to mention chance of 6SM BR at OTM Sunday morning, VFR conditions will prevail with light winds through the period. && .DMX WATCHES/WARNINGS/ADVISORIES... Heat Advisory until 8 PM CDT this evening for IAZ062-073>075- 081>086-092>097. && $$ DISCUSSION...Krull AVIATION...Ansorge
National Weather Service Sioux Falls SD
1052 PM CDT Sat Jul 24 2021 .SHORT TERM...(This Evening through Sunday) Issued at 255 PM CDT Sat Jul 24 2021 Fairly quiet weather expected through the daytime hours Sunday, as weak surface ridge slides through the forecast area. Will continue to see filtered sunshine as smoke aloft streams across the region. Could see briefly reduced visibility at the surface this evening as well, as HRRR smoke model indicates potential for near surface smoke currently across southwest ND/northwest-north central SD, streaming eastward in a narrowing band behind a weak boundary before generally dissipating later tonight. Visibility in these areas, as far east as Mobridge as of 18Z, generally 5-6SM, so really a minimal impact in that regard, but could result in a faint smoky smell if outdoors. Also of note in the near-term is advancing of drier air behind the aforementioned boundary. Dew points mixing down quite well across northwest SD and far western ND, with readings in the 30s and even some upper 20s as of 18Z. This in contrast to our readings still in the mid 60s-around 70 over most of our forecast area. Feel this dry air will be tempered slightly by evapotranspiration from the more robust crop coverage in this part of the region, but still expect dew points to fall into the 50s-lower 60s through this evening. Along these same lines, some models, largely those with FV3 core, are depicting these ultra-low dew points mixing down into our northern counties Sunday afternoon. Again, though, recent rain in the Highway 14 corridor, along with evapotranspiration may have some impact in holding these readings higher. Thus will favor blended solutions which keeps afternoon dew points in the mid 50s across our north, with some lower 60s in northwest Iowa, as the surface winds turn light southerly behind the exiting weak surface high. With this drier air in place, and lack of any trigger prior to 00Z, think it will be tough to see storm development during the afternoon hours. Exception may be in our extreme west, as a mid-level wave approaches the Missouri River through western SD, though timing of this wave may favor early evening development after 00Z. .LONG TERM...(Sunday Night through Saturday) Issued at 255 PM CDT Sat Jul 24 2021 As a weak mid-level shortwave slides east across South Dakota late Sunday into Sunday night, could see isolated-scattered storms across mainly our western and northern counties. Deep mixing results in dry lower levels with inverted-V profiles beneath 650-600mb. If storms develop with this wave, could see isolated strong to severe winds, as indicated by the Day 2 SPC Marginal Risk across our far western counties. Similar to last night, though, think this threat should wane as we progress through the late evening/nighttime. First half of next week will be dominated by strengthening upper ridge which once again builds over the InterMountain West through Tuesday. NBM continues to project potential for high temperatures topping the century mark in several portions of our forecast area by Tuesday and Wednesday, but these values are running higher than the 50th percentile of NBM members. Given the continued potential for an elevated smoke layer across the region with the upper ridge axis to our west and northwest flow into the Upper Midwest, have nudged the highs for these days a bit closer to that 50th percentile. This still yields some triple-digit readings in our western counties, and triple digit heat indices farther east, though the latter will highly depend on whether dew points hold in the upper 60s-lower 70s or mix a bit lower in the low level southwesterly flow. Slight breakdown of the ridge during the latter half of the week could allow weak shortwaves to slide through the forecast area Thursday into Saturday. Timing/strength at this range is uncertain, so did not alter the smattering of 20-30 percent pops in the longer range portion of this forecast period. More sensible impact of any waves may be to bring some modest "cooling", though highs still likely to hold above normal as we approach the end of July. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1052 PM CDT Sat Jul 24 2021 Winds have become light and variable tonight and will remaining so before turning primarily southerly by the mid-late morning hours Sunday. Patchy valley fog is possible tonight, though not likely impacting a TAF site. Scattered showers and thunderstorms become possible late tomorrow afternoon across central SD, but have left mention out of this set of TAFs due to time and location uncertainties. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...JH LONG TERM...JH AVIATION...APT
Area Forecast Discussion
National Weather Service Glasgow MT
819 AM MDT Sat Jul 24 2021 .DISCUSSION... ...Heat returns on Sunday... 815AM UPDATE: Changes to the forecast this morning were fixated on refreshing the 7 hour old HRRR data for smoke and haze. Reduction in visibility have already reduced to 3 to 5 miles across Glasgow, Wolf Point, and Poplar and air quality has recently changed back to unhealthy for Malta. So, these updates were to help zero in on impacts to our TAFs in aviation weather and public health hazards. Visibility should improve slightly across the Hi-Line in the afternoon as the atmosphere mixes out. GAH MORNING DISCUSSION: A dry air mass and a ridge of high pressure will be over the forecast area today. While skies will be clear, smoke and haze from numerous wildfires will be over the area. Highs will be near 90 in most areas with cooler temperatures near the Canadian border. The upper ridge builds into the area starting on Sunday which will bring the heat back into the region. Sunday`s highs will be in the 90s in most areas with a few locations near 100. Most areas will have highs on Monday between 100 and 105. The ridge peaks on Tuesday and it looks to be the hottest day with highs 100 to 110 in most areas. Some areas near the Canadian border could stay below 100. At this point, Monday will need either a Heat Advisory or Excessive Heat Warning and Tuesday will need an Excessive Heat Warning. It is far enough out at this point to wait on issuing highlights. The ridge back slightly to the west Tuesday Night and Wednesday. A cold front Tuesday Night will bring somewhat cooler temperatures in the 90s on Wednesday. Weak waves could bring a slight chance of showers and thunderstorms Thursday and Friday. && .AVIATION... LAST UPDATED: 1400Z FLIGHT CAT: VFR - MVFR. Smoke might reduce visibility to MVFR at times. SMOKE AND HAZE: Smoke and haze across the area are here to stay for the next 3 to 4 days. These will reduce slantwise Visibility to MVFR on occassion, especially during the morning hours. There is already enough smoke and haze in the air that it is causing the KGGW and KOLF to report a false ceilings of around 5000 feet in the mornig hours. DISCUSSION: Skies will remain clear/dry today and tonight with high pressure over the area. WIND: Light and variable this morning. Becoming northwest this afternoon around 10 knots. Look for north to NE winds 5 to 10 knots this evening and east to NE winds around 5 knots late tonight. /GAH && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$
Area Forecast Discussion
National Weather Service Green Bay WI
1025 PM CDT Sat Jul 24 2021 Updated aviation portion for 06Z TAF issuance .SYNOPSIS... Issued at 228 PM CDT Sat Jul 24 2021 Less humid tonight through Monday, then humid conditions returning with a few rounds of thunderstorms from Monday night through Wednesday night. A little cooler and drier for the latter part of the work week. A strong band of westerlies (for mid-summer) will persist across the northern CONUS and southern Canada throughout the period, with a longwave ridge position in the west and a trough in the east. Amplitude will initially be quite modest, but increase a little late in the period as a broad upper anticyclone strengthens from the Intermountain West to the mid/lower-Mississippi Valley. The pattern favors above normal temperatures through at least the middle of the upcoming work week, with at least a little cooling possible late in the period as the upper flow tilts more northwesterly. The reservoir of very humid air will shift south of the area for a time early in the period, then return north into the area for a few days before shifting south again. Precipitation totals are tough to gauge as they will depend on the behavior of convection. The humid air mass across the area in the Mon night/Wed time frame will likely support some heavy precipitation--the big question is how widespread it will be and where it will occur. && .SHORT TERM...Tonight and Sunday Issued at 228 PM CDT Sat Jul 24 2021 The latest RAP analysis and satellite/radar imagery show a cold front extending across northern Lake Michigan to the central WI lakeshore early this afternoon. Strong mid-level drying is occurring in the wake of the thunderstorm activity and along and behind the front. A strong push of lower dewpoint air trails well behind the front, however, across northwest WI. A few convective allowing models regenerate a few showers/storms along this moisture gradient late this afternoon (like the NamNest), but think this may be overdone considering mixing has started over north-central WI, convergence is weak, and boundary layer moisture is likely too high. Based on the latest trends, added an isolated shower mention over far northeast WI for the rest of the afternoon. Other than the possibility of redevelopment of convection this afternoon, forecast concerns mainly revolve around temps through Sunday. Tonight...High pressure from the northern plains will build into the region. The airmass will be very dry as evident from a lack of convective clouds over the northern Plains where precipitable water values fall to 0.50 inches at KBIS. Will therefore have mostly clear skies with haze from smoke aloft. Stayed closed to low temps from the previous forecast. Sunday...High pressure along with the very dry airmass will be hanging across the region. Under sunny skies, low level temps support highs in the middle 80s to low 90s. But with seasonably low dewpoints, apparent temps should be near actual air temps. .LONG TERM...Sunday Night Through Saturday Issued at 228 PM CDT Sat Jul 24 2021 The focus of the long-term portion of the forecast was on conditions Monday through Wednesday night. That is when the return of very warm/hot and humid air will correspond with seasonably strong WNW upper flow, possibly setting the stage for a few rounds of storms--some of which could be severe. Dew points will begin to increase Monday, but the day should be rain-free across most of the area. It is possible some convection may affect the far north/northeast as a weak boundary lingers just to the north and the area gets brushed by the tail of a shortwave sliding SE across Ontario. The potential for storms to build south into the forecast area will increase Monday evening/night. SPC has outlooked the NW 2/3 of the forecast area with a Marginal Risk during this time. A very humid and unstable air mass will be in place across the area by Tuesday. It is possible that temperatures around 850-800mb will be warm enough to provide a cap and inhibit convection. But it is also possible an outflow from any storms Monday night may be lingering across the area and provide convergence which could break the cap. A similar set-up will persist Tuesday night into Wednesday, then a more substantial synoptic scale cold front will shift through the area. The medium range models were not in good agreement on the placement of the front/timing of FROPA. The large scale pattern certainly seems supportive of a severe threat at some point during this period. Right now, Wednesday night looks like the most likely time, though that may change with time as smaller scale details become clearer. Another round or two of scattered convection is possible during the remainder of the period as shortwaves drop SE in the strengthening NW upper flow across the forecast area. && .AVIATION...for 06Z TAF Issuance Issued at 1025 PM CDT Sat Jul 24 2021 Very minor changes to 06Z TAFs. VFR flying conditions are expected with mainly clear skies and good visibility. Winds will remain light from the west overnight, and then increase Sunday afternoon with gusts ranging from 15 to 20 knots. Winds will once again subside Sunday evening. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS.......Skowronski SHORT TERM.....MPC LONG TERM......Skowronski AVIATION.......KLJ
Area Forecast Discussion
National Weather Service Shreveport LA
907 PM CDT Sat Jul 24 2021 .UPDATE... Dry and stable conditions to continue overnight as surface and upper-level ridging prevail areawide. Warm temperatures expected overnight with lows forecast in the mid to upper 70s. Otherwise, light winds and clear skies to prevail. No updates necessary at this time. /05/ && .PREV DISCUSSION... /issued 619 PM CDT Sat Jul 24 2021/ AVIATION... VFR conditions to prevail across area terminals through the forecast period ending 26/00Z. Could see VCTS conditions across MLU from 25/18Z through 26/00Z. Otherwise, light and variable winds tonight to become southwest at 5 to 7 knots on Sunday. /05/ PREV DISCUSSION... /issued 307 PM CDT Sat Jul 24 2021/ SHORT TERM.../Tonight through Sunday Night/ A strong upper level ridge continues to move slowly westward into Central Texas while a surface ridge in the Northwest Gulf of Mexico has drifted towards the Southeast Texas coast. The approach of the ridges and increased subsidence have kept the forecast area precip-free so far today. Westerly or northwesterly winds south of the area have prevented any intrusion of the sea breeze. With the decrease in cloud cover and rain chances, temperatures warmed fairly quickly, especially across Southern Arkansas and Northern Louisiana. Heat index values have already started to fall below criteria over portions of Northeast Louisiana as increased vertical mixing have finally brought dry air advecting into the region in the 925-850 hPa layer down to the surface. However, the current advisory will be maintained through 00z. The HREF and HRRR continue to suggest isolated to widely scattered convection will develop during the overnight through mid morning hours of Sunday over Eastern Oklahoma and into Southwestern Arkansas. This is expected to occur along an elevated theta-e ridge. However, most of the other model guidance, including other high-resolution CAMs remain dry. Given the uncertainty, I decided to keep the forecast tonight/Sunday morning dry, but later shifts may need to introduce PoPs in convection appears more likely. Sunday should be relatively similar to today. The two ridge will move farther inland over Texas, which may allow for some an expansion of chance for isolated convection Sunday afternoon. Decrease vertical mixing should create a more humid airmass. Daytime highs should be a few degrees warmer than today, which means more of the area will likely see heat index values above advisory criteria. Therefore, another Heat Advisory was issued for Sunday for Southeast Oklahoma, all of Southwest Arkansas, most our Louisiana parishes, and portions of Northeast Texas. I would not be surprised if heat indices climb above 110 degrees F over portions of Northeast Louisiana. An upgrade to an Excessive Heat Warning for a part of the area may be needed by later shifts. CN LONG TERM.../Monday through Saturday/ The dogs days of summer are pretty much upon us, but we are fortunately hanging on to all the green-up of our wet Summer start. As our rain chances drop off again for mid to late week, we will further erode this albedo benefit with upper 90s becoming a bit more common during this timeframe and perhaps some triple digit air as well. The upper level heights have already been creeping upwards, boosting the mercury just a bit under the recent 594 core, but a window of brief reprieve is approaching. Overall, we are looking at the front range breeding the higher heights this week as compared to the more forgiving Bermuda ridge, which will keep just offshore of the SE U.S. However, a weak frontal boundary will drop out of the Great lakes into the Ohio Valley on Monday with a 1017mb surface high. There is also a weak upper low of 589dam associated with an inverted trough over the coastal bend of Texas which will help to foster a decent sea breeze push for Monday over our East and hopefully a bit more areawide into Tuesday. Beyond this window for opportunity for better than average rainfall, the heat will build under better subsidence and heights building through midweek as the inverted trough dampens while sliding down toward the Mexican coast over the west Gulf. The dominant upper ridge over the high plains will drop into the plains and MS river valley. This will effectively squash the sea breeze except for our southern tier of Parishes for the most part. On Tuesday the core will be near 595dam over the central plains and by the mid and ending part of this work week, we will see this upper level feature build to 597dam on both GFS and ECMWF centered right over Kansas, while covering a vast expanse of the nation`s heartland. Coverage of convection for us will be slim to none for many of our zones. Afternoon heat indices will be around the 105 range every afternoon, possibly higher by a few degrees during the hottest hours of the day. The issuance of Heat Advisories continues daily for now, but may come to include the overnights by late in this period. Remember to move strenuous activity to early or late in the day, try to stay hydrated by drinking water before, during and after exposure. Try to take frequent shade or A/C breaks, and wear loose, light-colored clothing and hats. Special care should be taken to ensure the well- being of the elderly, young children and a pets and livestock during late July. /24/ && .PRELIMINARY POINT TEMPS/POPS... SHV 77 99 77 98 / 0 10 10 20 MLU 77 97 76 97 / 0 20 10 50 DEQ 75 97 75 97 / 10 20 10 30 TXK 77 99 77 97 / 0 10 10 30 ELD 75 96 74 97 / 0 20 10 40 TYR 75 96 76 98 / 0 0 0 10 GGG 74 96 74 97 / 0 10 0 10 LFK 74 97 75 98 / 0 0 0 20 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...Heat Advisory from 10 AM to 7 PM CDT Sunday for ARZ050-051- 059>061-070>073. LA...Heat Advisory from 10 AM to 7 PM CDT Sunday for LAZ001>006- 011>014-018>022. OK...Heat Advisory from 10 AM to 7 PM CDT Sunday for OKZ077. TX...Heat Advisory from 10 AM to 7 PM CDT Sunday for TXZ096-097- 108>112. && $$ 05/09/24
Area Forecast Discussion
National Weather Service Sacramento CA
150 PM PDT Sat Jul 24 2021 .SYNOPSIS... Dry weather with temperatures warming into the weekend. Chances for mountain thunderstorms this weekend through next week. && .DISCUSSION... High pressure building over the Desert Southwest is setting up for a prolonged monsoonal moisture push into Northern California. In the short term there may be an isolated shower or thunderstorm later this afternoon around Alpine county southward along the crest. Smoke from the Dixie wildfire has been slower to improve over the interior than what the HRRR is suggesting but does have it improving overnight and Sunday as it pushes the smoke towards the east. More moisture will arrive starting on Sunday but the big increase will occur late Sunday night and Monday morning when we should see a noticeable increase in cloud cover. Precipitable waters will be high so any thunderstorms should have heavy rain associated with them. Questionable time period will be Monday night through Wednesday when there would be some potential for storms at lower elevations. For now most of the activity is forecast to stay over the mountains but that could change. A decent Delta breeze will occur through Monday before becoming lighter on Tuesday. Temperatures will trend cooler through Monday. By Tuesday the low clouds along the coast will likely be getting mixed out which in turn will lead to a weaker Delta breeze and warmer inland temperatures. && .EXTENDED DISCUSSION (Wednesday THROUGH Saturday)... Wednesday there is an interesting feature that we will need to pay close attention too. An upper level circulation will move northward through the valley during the day. This time of year and with the moisture that will be in place showers and thunderstorms will probably have there greatest chance of getting into the valley. For Thursday through the rest of the extending period the monsoonal moisture gets pushed to the crest. There may be some slight warming late next week then cooling over next weekend as the high pressure weakens over the Desert Southwest. && .AVIATION... VFR conditions are generally forecast to prevail over the next 24 hours except for areas of MVFR as a result of wildfire smoke generally north of I-80 in the mountains and over the far north end of the valley. Conditions should improve overnight in the valley with a chance for the foothills improving Sunday morning. Areas of smoke will also persist around Alpine county. Surface wind gusts under 12 kts except local southwest gusts 20-30 kts vicinity west Delta. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$
Area Forecast Discussion
National Weather Service Las Vegas NV
823 PM PDT Sat Jul 24 2021 .SYNOPSIS...A large circulation moving in from Arizona will bring additional moisture and lead to extensive showers and thunderstorms across our region through Monday. After this disturbance passes by, lower thunderstorm chances are expected Tuesday through Thursday. && .UPDATE...We are monitoring one final cluster of storms over northwest Clark County, near Indian Springs. Storms have produced up to 0.40" of an inch of rain in the past hour with some reports of winds around 50 mph. Area is moving southwest into less favorable environment over southern Nye County and would expect this area to dissipate over the next 2-3 hours. Otherwise, we are seeing some light showers or sprinkles from Las Vegas southeast across central Mohave County. Area of stratiform light rain over Mohave County is forecast to hold together as it moves south toward the lower Colorado River Valley and Bill Williams River overnight. Rainfall amounts on the Flag Burn Area and the rest of the area should be less than 0.10". Touched up the forecast for the rest of tonight limiting any threat of thunderstorms to northwest Clark County and parts of Mohave and eastern San Bernardino County. && .AVIATION...For McCarran...Southeast wind less than 10 kts favored overnight with winds eventually becoming light and variable toward daybreak Sunday. Scattered to broken clouds above 12 kft tonight and Sunday with an east or southeast wind less than 10 kts favored Sunday afternoon. Low confidence if thunderstorm will impact the valley terminals Sunday evening. For the rest of southern Nevada, northwest Arizona and southeast California...Thunderstorms will be dissipating across southern Nevada and northwest Arizona by lat evening. Partly to mostly cloudy skies overnight with light showers possible overnight across southern Nevada, northwest Arizona and eastern California. Ceiling will range between 6 to 10 kft AGL. Expecting another round of storms to develop over the higher terrain of southwest Utah and northwest Arizona Sunday afternoon and drift southwest toward southern Nevada, lower Colorado River Valley and eastern California. Heavy rainfall and gusty winds may impact some terminals. $$ .SHORT TERM...through Sunday night. Scattered thunderstorms moving from northeast to southwest during the late afternoon and evening hours will remain a threat for northwest Arizona and southern Nevada through Sunday. The northeast steering flow driving the thunderstorms out of southwest Utah and southern Lincoln county is a result of the approaching large inverted trough crossing Arizona and the counterclockwise flow around the 500 mb high which will remain centered between Reno and Tonopah through Sunday afternoon. Recent mesoanalysis reveals a tongue of precipitable water values 1.5-1.9" extending from central and eastern Clark County down through Mohave and eastern San Bernardino counties. This area has been under considerable cloud cover this morning but more heating will occur through the afternoon as clouds breakup somewhat. The best ML CAPE values of 1000-1500 J/kg will be over northeast Clark county extending down across Lake Mead into central Mohave County providing the most unstable environment for storms to move into. However, as storms coming from southwest Utah gain momentum, outflow could merge with storm outflow from southern Lincoln County leading to storms developing toward the Las Vegas Valley this evening. However, the latest HRRR and HREF members focus the majority of storms over Mohave County and Lake Mead to Laughlin-Bullhead City and even Lake Havasu this evening with Las Vegas mainly getting brushed by gusty northeast or east winds. Storm coverage will diminish overnight then a very similar setup remains in place for thunderstorms that develop Sunday afternoon and evening. The axis of the inverted trough is forecast to move over southern Nevada and southeast California between 00Z and 12Z Monday, so showers will likely expand Sunday night into Monday morning across Clark and eastern San Bernardino counties due to the dynamic forcing along the leading edge of the trough. However, the 12Z HREF members show little any the way of thunderstorms across our region between 06Z and 12Z Sunday night. This would not support expanding the Flash Flood Watch beyond Mohave County and the Colorado River Valley. Western San Bernardino, Inyo, Esmeralda and Nye counties will see showers and thunderstorms spreading across late Monday morning through the afternoon. .LONG TERM...Tuesday through Saturday. Chances for showers and thunderstorms decrease Tuesday through Thursday as drier and more stable air moves in behind the inverted trough as it lifts away. Another inverted trough is forecast to lift from northern Mexico up across our region late in the week leading to another injection of moisture into our region. NBM probabilities of precipitation trend upward into the 20-40 percent range for much of the region Friday and Saturday. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && UPDATE/AVIATION...Pierce SHORT TERM/LONG TERM...Adair For more forecast information...see us on our webpage: or follow us on Facebook and Twitter