Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/15/22

National Weather Service Wakefield VA
953 PM EDT Thu Jul 14 2022 .SYNOPSIS... A weak frontal boundary will remain nearly stationary over eastern and southeast portions of the area into Saturday morning, before dissipating. Expect shower and thunderstorm chances to persist each day, with the best chances being along and southeast of the frontal boundary. More diurnally driven showers or storms will be possible Saturday and Sunday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... As of 950 PM EDT Thursday... Latest analysis reveals weakening frontal boundary remaining draped across the eastern Tidewater area, extending SSW into N GA, extending back into the Red River valley. To the north, a weak piedmont trough remains in place from northern VA into western VA and eastern KY. Isolated to widely scattered showers have popped up from time to time along this boundary this evening, and a few showers will remain possible into the overnight over far northern sections. Meanwhile, across the south/SE zones, coverage has remained mainly south of the Albemarle Sound. However, incoming 00z/15 CAMS and the past few runs of the HRRR show showers inching a bit closer to our far SE coastal zones overnight, as elongated shortwave trough nudges closer to the area along the frontal zone, where good instability (1500-2000 J/Kg of MLCAPE) and moisture (PW 1.75-2") remain in place. Thus, will stick with 40-50% PoP overnight for additional scattered showers and storms. Any of these storms will be capable of producing some briefly heavy, rather efficient rainfall with warm cloud depths AOA 4 km. Remaining warm and somewhat muggy overnight with temps in the low-mid 70s. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... As of 300 PM EDT Thursday... Latest guidance suggests the front will become a little more active on Friday as a weak upper disturbance currently over the Great Lakes moves across the region. Severe weather unlikely given the weak wind fields, however localized heavy rainfall is possible given the slow movement of the storms and some possible training of the storms as the front will be nearly parallel to the mean flow aloft. Best chance for showers/storms will be across southern/SE VA into NE NC where we will forecast likely PoPs. Will also mention heavy rainfall in the forecast and include a mention of localized flooding in the HWO given the marginal ERO. The front remains near the region on Saturday, with the models suggesting continued troughiness aloft. This suggests scattered convection once again on Saturday afternoon/evening. Cannot pin point exactly where the best concentration of convection will be given that this will be influenced by localized boundaries, etc. As such, will place the whole area in a chance of thunderstorms Sat afternoon. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 300 PM EDT Thursday... Typical summer time weather with seasonable heat/humidity as upper heights remain near or slightly above normal through the week and the Bermuda high stays in place off the SE coast. Expect mainly pop up afternoon and evening showers and storms each day, although there are hints of better chances for storms on Monday with a surface trough moving through and some lowering heights. Perhaps a better chance for storms on Wednesday and even Thursday as a stronger upper trough approaches from the NW. Overall temps will be in the lower 90s on Monday, rising to the low- mid 90s Tue/Wed. Temps perhaps drop back slightly on Thursday but still upper 80s/lower 90s. Lows generally mild in the 70s. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... As of 745 PM EDT Thursday... Generally good flying conditions across area terminals this evening. However, while VFR conditions are expected to prevail across our terminals through the 00z TAF period, we are noting some showers developing along the cold frontal boundary in eastern NC this evening. CAMs showing potential for some scattered showers reaching the ECG terminal in the next few hours, with some additional showers then possible late tonight into Friday morning before diminishing. Some short- lived flight restrictions are possible at ECG in heavier showers, but chances are too low to include in the TAF at this time. Outlook...The front will buckle back north slightly across SE VA, with more widespread convection then expected Fri afternoon over SE terminals. This could portend some additional brief flight restrictions, most likely at ECG/ORF/PHF. Otherwise, a typical summertime pattern in place, with additional isolated to scattered storms expected mainly each afternoon and evening through early next week. && .MARINE... As of 300 PM EDT Thursday... A nearly stationary front lingers just inland through Fri before becoming washed out. This will allow for daily diurnal afternoon/evening shower/storm chances through at least early next week. Otherwise, typical summer pattern with no significant FROPA expected over the next week and sub-SCA conditions continuing. Winds this afternoon are light SW (~5 kt), becoming SE 5-10 kt across the Ches Bay and rivers later this afternoon, then becoming S ~10 kt this evening before becoming variable 5-10 kt overnight as a weak surface low moves over the Ches Bay. Winds become SE 5-10 kt across the S coastal waters and E across the N coastal waters Fri, becoming SE everywhere Fri evening. The strongest winds arrive late Sun through Mon night when S winds (becoming SW Mon night) increase to 10-15 kt across the bay and 15-20 kt across the coastal waters. Will continue to monitor trends as we get closer. Waves and seas remain 1- 2 ft (mainly 1 foot except the mouth of the bay) and 2-3 ft respectively through Sat night. There will be a moderate rip risk for the northern beaches on Fri given onshore flow and periods of 9-10 seconds. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...TMG NEAR TERM...MAM/MRD SHORT TERM...MRD LONG TERM...MRD AVIATION...MAM/MRD MARINE...AJB/RMM
Area Forecast Discussion
National Weather Service Bismarck ND
939 PM CDT Thu Jul 14 2022 .UPDATE... Issued at 934 PM CDT Thu Jul 14 2022 With this update fog was added to much of western and central North Dakota for early Friday morning. Upslope flow, likely low dew point depressions at the surface, and subsidence will potentially lead to fog development. 00Z high-res visibility guidance indicates this potential well, as do forecast soundings. UPDATE Issued at 852 PM CDT Thu Jul 14 2022 Water vapor imagery shows mid-level shortwave and associated dry, subsident signature, well into central North Dakota at 0144Z. The 00Z BIS RAOB shows a subsident sign as well, with backing wind in the mid-levels and an obvious warm nose above 850mb. Several attempts at convective initiation occurred this evening in northwest North Dakota, none able to produce lightning before dying off. What may be a last attempt at convective activity for central North Dakota is a storm approaching Rolette county from the north, healthily showing severe potential on MRMS. This will continue to approach more capped air as it moves south and the 00Z HRRR depicts this cell weakening substantially as it approaches the border. Additionally, convection is moving through southeast Montana, but again should weaken as it approaches North Dakota and surface temperatures fall. With this update we kept a slight chance of a thunderstorm in the north central in the forecast, but otherwise cut back PoPs. UPDATE Issued at 559 PM CDT Thu Jul 14 2022 23Z surface analysis depicted a somewhat diffuse pressure field, with weak convergence over western North Dakota. Isentropic ascent driven convection continues over the northern James River Valley, which should continue to exit east through the evening. As a mid-level impulse continues to move into North Dakota this evening, an isolated thunderstorm or two remains possible, maybe more likely northwest to north central where the arriving shortwave and surface convergence best overlap. Previous discussion of the highly conditional severe potential remains valid. The probability for isolated convection should decrease after sunset as the boundary layer decouples. && .SHORT TERM...(This evening through Friday) Issued at 304 PM CDT Thu Jul 14 2022 Thunderstorms are expected to continue across the central and eastern portion of the state this afternoon through evening. The severe weather forecast this afternoon is quite tricky. The KBIS morning soundings came in with a pretty stout cap up to 850 mb. Remnant clouds from the shortwave trough earlier this morning which has hindered sfc heating east of HWY83. This leads to an unfavorable environment across the south central and eastern part of the CWA. According water vapor imagery to the second shortwave is currently ahead of schedule moving across the northwest portion of the state. The vorticity maxima looks to be well north of the International Border. However the environment is primed for severe weather with MU CAPE values of 3000-4000 j/kg, 1000-1500j/kg of DCAPE, and 40-45 kts effective shear across the western portion of the state. If storms are able to organize there is no doubt there could be very large hail and gusty winds, but what was iterated in the beginning of the this discussion was the lack of a forcing mechanism out west. This will be the cause for reduced chances of severe weather this afternoon. Subsidence will follow this evenings convection clearing skies for tomorrow. Tomorrow`s temperatures are forecast to climb into the low 90s across the southwest part of the state as a low level thermal ridges settles over eastern Montana. Another round of convection makes it`s way through tomorrow night across the western portion of the state from another upper level shortwave trough. There is an isolated chance for strong to severe thunderstorms moving out of Montana Friday evening. Thunderstorms will continue through the nighttime hours with the severe threat diminishing overnight. .LONG TERM...(Friday night through Thursday) Issued at 304 PM CDT Thu Jul 14 2022 Saturday morning, a shortwave trough will progress eastward through the Northern Plains bringing precipitation to the region. Convection will likely continue across the central portion and eastern portion of the state by Friday afternoon. Thunderstorms and showers could linger through the afternoon across south central North Dakota as the wave lingers. However, the Saturday morning convection will likely work over the atmosphere hindering afternoon severe chances. Temperatures are forecast to warm into the mid to upper 90s Sunday afternoon as an upper level ridge builds over the Northern Plains. However, the low level thermal ridge will remain mostly over eastern Montana with the western periphery clipping the southwest portion of the state. Fortunately the ridge is temporary in nature as an upper level low is going dive into the northern rockies. This will temporarily shift the low level thermal ridge over south central North Dakota leading to a very hot day across the southern portion of the state. Monday, dew points in the 60s and highs forecast to reach the upper 90s could have heat index approaching 100F. The aforementioned low will quickly move into the state Tuesday bringing a reprieve from the heat and some precipitation. The low may trek a bit further north placing much of the state in the an unfavorable location for precipiation. Ensembles are already highlighting higher possible Tuesday as the low moves through the region. After that the upper level pattern becomes more zonal with embedded shortwaves through the extended. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 939 PM CDT Thu Jul 14 2022 Recent guidance has given higher chances for fog to develop over areas of western and central North Dakota between 09Z and 14Z. How severe visibility and ceiling reductions become is uncertain at any location, but periods of IFR to possibly LIFR visibility will be possible. Conditions expected to improve to VFR after 14Z. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AE SHORT TERM...Johnson LONG TERM...Johnson AVIATION...AE
Area Forecast Discussion
National Weather Service Des Moines IA
638 PM CDT Thu Jul 14 2022 ...Updated for the 00z Aviation Discussion... .DISCUSSION.../Tonight through Thursday/ Issued at 227 PM CDT Thu Jul 14 2022 Take Home Points: *Heat to end the week, then cooler weekend *Storm chances remain tonight and portions of weekend *Heat builds back in early week Discussion: Generally speaking, it has been a quiet day across the area weather wise. Warm front has lifted through the state and helped temperatures reach around 90 as for early this afternoon across the SW forecast area. Areas mainly west of I-35 or south of I-80 remain on track to top out in the low 90s, with the bulk of the heat just to our west and across the Missouri River. Widely scattered light rain activity from this morning pushed eastward and dissipated as expected as well. One little anomaly this morning was the longevity of LLJ and WAA induced storms back in SE Nebraska, however has dissipated as of this writing. Broadly speaking, the forecast is devoid of large changes/alterations, but has seen some trends continue... For tonight, compact shortwave remains on track to move through the region and bring with it areas of convection. What has changed though is the track continues to move northward compared to the previous couple of forecast cycles. Current hi-res guidance places the core track of storms/MCS across C/SE Minnesota and into SW Wisconsin, more closely tied to the core of the shortwave and anticipated area of better MUCAPE, around 1000 J/kg or greater. Elevated nature and primarily unidirectional shear profiles suggest a primary wind threat with those storms, but again, expected NE of the CWA at this point. Back into Iowa, recent HRRR runs have trended upward with regards to scattered convection, largely around/after 08z and tied to strong isentropic lift through the low to mid levels. Model soundings suggest these storms would be rooted around/above 700mb, 10kft. Similar to above noted situation, mostly unidirectional shear at that layer and above and nominal CAPE will limit severe potential. Noted dry air below though will give some potential for accelerating down drafts and could yield some gusty winds at the surface, but hard pressed to see much of a severe threat. Current SPC Day 1 remains reasonable with a Marginal into the area. This activity should wind down/exit E/SE through the morning Friday. In its wake, Friday shapes up to be another warm/hot day with highs boosted a degree or two, into the mid 90s from roughly Highway 30 on south as the thermal ridge continues to flirt with the CWA. Should the 900mb-850mb warm nose not make it into central Iowa though, temps will be couple/few degrees to warm, so a bit of uncertainty in/around Des Moines/Ames. Into the weekend, the convective potential remains messy. The shortwave train through the NW flow will continue, with guidance beginning to come into better agreement. Area to see the greatest opportunity points towards roughly the SW half of the state from Saturday afternoon into the overnight as weak to moderate forcing moves through. The lobes of forcing are misaligned, with upper level better over NE Iowa and low level/thermo better to the SW. Drier air to the NE will limit coverage that direction, while large area of warm air/cap will limit daytime potential. Areas SW may see eventual MCS formation as LLJ increases overnight, but most likely into Missouri. Model trend has been southward for the main areas of convection, so that will need to continue to be watched, with NBM PoPs appearing to remain too aggressive still/playing catch up in N/NE areas. Temperatures through the weekend will ease back into the 80s under influence of northerly winds and periods of lingering cloud cover. The "cool" temperatures will not last though as Rockies/western High Plains ridging is shoved a bit eastward ahead of a PNW shortwave trough. This will yield a period of quiet weather/sunny skies, but come at the cost of heat building back in. Fortunately, the core of the ridge will be squashed by the aforementioned shortwave trough before it can build too much into the state. Expect highs in the mid 90s over large portions of the W/S CWA and a few degrees cooler to the NE early in the week. && .AVIATION.../For the 00Z TAFS through 00Z Friday evening/ Issued at 635 PM CDT Thu Jul 14 2022 VFR conditions currently prevail across central Iowa. Scattered TSRA develops overnight and moves south and east into Friday morning. Included a mention of VCTS at all TAF sites after 08z to highlight the potential, however the timing, location, and categorical impacts of any TSRA activity remains uncertain at this time. Trends will be monitored and amendments made as conditions warrant. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Curtis AVIATION...Martin
National Weather Service Hastings NE
651 PM CDT Thu Jul 14 2022 .DISCUSSION...(This evening through Thursday) Issued at 309 PM CDT Thu Jul 14 2022 Main forecast problems include excessive heat for the next couple of days, and for next week. Also, small chances of afternoon/evening storms next few days. The upper level jet stream will remain well north of our area and the upper level ridge will dominate our overall weather for the next several days. This means a lot of heat and only limited chances of precipitation. Today we sit squarely in the warm sector For late this afternoon and this evening. Cold front will make its way into the northern Plains, but will remain way too far to the north to be consequential to us. Any outflow boundaries from morning storms should be washed out by the south breeze we have going today. This breeze will help the heat to be somewhat more bearable. Some hi-res models are indicating a chance of thunderstorms sliding through the area, especially north/northeast CWA. We will have a bit of a cap to contend with as 700 mb temps will be between 13C and 17, being greater in the western CWA. With not much forcing to help break the cap, coverage would probably be very limited for surface based convection, so this looks like mainly elevated convection if it occurs this evening, with still some inhibition to contend with. Deep layer shear will be weak, near 25 KTS, but if we can get elevated storms to go, HREF means indicate 1500 to maybe 2000 J/kg instability where storms more likely develop (north/northeast). Cloud bases look like they would possibly be near 10-11K feet. Timing for the tri-cities seems centered around 8 PM to midnight for the tri-cities from the HRRR and NAMNest if anything occurs, and overall, the HREF does not seem too hopeful for there being much coverage if storms do develop. Heat concerns will subside as we get toward sunset. Friday will be similar to today as the heat index will be close to, if not more than today in some places. The Heat Advisory may need to be expanded for tonight`s forecast if it gets any warmer. Another shot at some storms Friday late afternoon and evening, and there may be a surface trough around for a focus for convection. The upper ridge with the axis over the Rockies decreases in strength just a bit over the weekend and takes on a bit of a positive tilt into the northern Plains. This has been consistently forecast by long range models, giving us a short slight reprieve from the heat over the weekend before becoming brutally hot all next week again. This so called reprieve means that highs will "only" make it into the 90s for most locations, before returning to near 100 degrees or more for the next work week. Precipitation chances remain small to non-existent for the rest of the forecast into next week. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday) Issued at 645 PM CDT Thu Jul 14 2022 Thunderstorms have been slow to develop this evening and recent forecast model trends indicate decreasing chances for thunderstorms tonight around our TAF sites. We can not completely rule out an isolated thunderstorm, but for now have removed mention of thunder from the TAF. The wind will shift to northerly behind a cold front Friday morning, but it really will not be much cooler behind the front, expect mainly northerly becoming northeasterly winds during the day on Friday. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Heat Advisory from 1 PM to 7 PM CDT Friday for NEZ082-083. KS...Heat Advisory from 1 PM to 7 PM CDT Friday for KSZ005>007- 017>019. && $$ DISCUSSION...Heinlein AVIATION...Wesely
Area Forecast Discussion
National Weather Service Grand Rapids MI
1042 PM EDT Thu Jul 14 2022 LATEST UPDATE... Update .UPDATE... Issued at 1040 PM EDT Thu Jul 14 2022 Have increased POPs for Friday afternoon and evening based on 18z/00z model guidance. Upper level jet divergence increases after 12z Friday with a 500 mb shortwave moving through during the afternoon and evening. At 850 mb, a 30-40 kt LLJ develops overnight and into early Friday though there is some question about how far north this gets, which is critical to placement and intensity of rainfall Friday. The 00z HRRR and NAM3km keep the nose of the LLJ centered across southern WI, southern Lake Michigan, and northern IL/IN. Meanwhile, the 18z GFS and ECMWF show the nose of the jet a bit further north...impacting SW Lower MI. Also noted is the rich reservoir of atmospheric moisture available for this warm advection rain event. The 18z ECMWF brings the 2.00" PW contour into SW Lower MI Friday afternoon. Also, the 18z EPS members are unanimously on board for measurable rain along and west of a Pentwater to Jackson line. However, the 00z HRRR and NAM3km suggest a sharp N/S gradient to the rain, leaving some question marks about where the axis of heaviest rain will set up and if some central and northern regions of our forecast area will get very light amounts. There remains a possibility that this axis of heaviest rain could intersect portions of southern WI into SW Lower MI for Friday afternoon/evening with 1"-2" possible, locally more. Will continue assessing the 00z guidance overnight and make adjustments. && .DISCUSSION...(This evening through next Thursday) Issued at 339 PM EDT Thu Jul 14 2022 -- Rain chances Friday afternoon into Sunday -- No change to previous thinking. Vigorous upper PV maximum currently forcing convection over eastern ND will be approaching the CWA from the northwest Friday. We are now close enough to the Friday and Saturday timeframe that we can leverage convection allowing models (and the HREF by extension) to refine our expectations to an onset of precipitation Friday afternoon for our western zones. This is supported as well by the most recent extended runs of the HRRR. We see indications in the PMM and LPMM guidance there could be localized amounts in excess of 2 inches Friday night. This is not surprising given that the HREF mean PWAT is pegged around 1.6" which in the 90th percentile according to SPC sounding climatology. Rich low-level moisture continues to stream into the area Friday night. By Saturday afternoon, mid 60s F dewpoints should be commonplace over the forecast area. Chance PoPs on Saturday afternoon and evening are completely warranted given the expected approach of another weak shortwave impulse and an associated apparent MCS moving east across southern Lower MI. Then, for Sat night-Sun night period, another midlevel shortwave impulse will traverse the region and we expect another uptick in precipitation, although the extent of that will be somewhat influenced by whatever happens during the day Saturday. As noted previously, precipitation efficiency for all of these events will be high and WPC shares these concerns with a marginal risk for excessive rainfall across much of southern Lower Michigan both Friday and Saturday. -- Monday and beyond -- No changes to previous thinking and therefore previous discussion is copied here verbatim: EPS and GEFS ensemble means suggest that a shortwave trough may flatten the mid/upper ridge along the U.S./Canada border on Mon. A robust surface cyclone accompanying this shortwave should provide broad warm advection for the Great Lakes region and warmer temps on Mon and Tue. EPS/GEFS members suggest that a fairly deep surface low may be situated over the northern Great Lakes on Wed, with cold-frontal passage through Lower Michigan possible during the Tue night-Wed timeframe. However, ensemble means still exhibit considerable run-to-run adjustments with this system. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 716 PM EDT Thu Jul 14 2022 For this TAF period, we are trending toward increasing cloud cover and lowering bases to around 4000 ft for Friday afternoon. This is in association with an area of rain moving into Minnesota presently. Rain chances will be increasing after 16z Friday especially for MKG, GRR and AZO. The threat for TSRA looks low at this time but cannot be ruled out especially late in this TAF period. && .MARINE... Issued at 339 PM EDT Thu Jul 14 2022 No concerns at this time. We currently see a well established lake breeze. However CMAN/buoy observations and webcams all indicate limited winds and waves. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ UPDATE...Hoving DISCUSSION...TJT AVIATION...Hoving MARINE...TJT
Area Forecast Discussion
National Weather Service Huntsville AL
1029 PM CDT Thu Jul 14 2022 ...New AVIATION... .NEAR TERM... (Tonight) Issued at 752 PM CDT Thu Jul 14 2022 The stationary surface boundary is located just to the south of the forecast area and is forecast to stay to the south throughout the overnight hours. The boundary is not hard to pick out with the dewpoint in Gadsden of 73 degrees and the dewpoint in Albertville at 59 degrees. Dewpoints are lower across the Tennessee Valley with most locations in the low to mid 60s with a few upper 50 readings. Winds are light and from the north. Water vapor imagery and RAP upper air analysis indicates a positively tilted trough located just to the north and west of the area. Water vapor imagery depicts extremely dry air aloft along the western periphery of the trough stretching from Great Lakes southwestward into the southern Plains. The atmosphere is already dry across the Tennessee Valley and dry air will continue to advect into the area as the upper trough axis shifts to the east of the area. PW values will drop down to around 1 inch later tonight. These values are near the minimum for mid- July PW climatology. Overall, not expecting any precipitation overnight. The dry airmass should allow for temperatures to drop down into the mid to upper 60s for most locations by Friday morning. Also, with the dry atmosphere, do not expect any fog formation overnight. && .SHORT TERM... (Friday through Sunday) Issued at 122 PM CDT Thu Jul 14 2022 On Friday, an upper level trough across the East Coast will gradually lift to the northeast. During the short term forecast period, the Tennessee Valley will be situated between the aformentioned trough and an upper level ridge across the Western Plains. As a result, a dry airmass will remain locked in place making for a dry end of the work week and through the first half of the weekend. Afternoon highs each day will be in the low to mid 90s with overnight lows in the upper 60s to lower 70s. Better moisture return on Sunday will allow for some isolated afternoon thunderstorms to develop. && .LONG TERM... (Monday through Thursday) Issued at 122 PM CDT Thu Jul 14 2022 By the start of next week, the upper level pattern becomes more zonal across the eastern third of the CONUS with the upper ridge situated over the Rockies. A shortwave along the eastern edge of the ridge drops down towards the Tennessee Valley with an associated front to its southwest. This will result in widespread showers and thunderstorms Mon afternoon through at least Tuesday morning. At this time, severe storm chances appear quite low given low shear. However, with PW values approaching 2 inches, expect any shower or storm to produce locally heavy rainfall, which may result in localized flooding. Model guidance still varies on the forward speed of the front, therefore have kept rain chances in the forecast through Tuesday evening. Starting midweek, a more typical summertime pattern sets up. Afternoon highs in the low to mid 90s with chances for diurnally driven thunderstorms. Overnight lows will be in the low to mid 70s. Due to the higher humidity, heat index values may reach the low 100s, but at this time they should remain below heat advisory criteria. && .AVIATION... (06Z TAFS) Issued at 1029 PM CDT Thu Jul 14 2022 VFR conditions will continue throughout the TAF cycle with light winds. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...None. TN...None. && $$ NEAR TERM...MA SHORT TERM....GH LONG TERM....GH AVIATION...MA
Area Forecast Discussion
National Weather Service New Orleans LA
951 PM CDT Thu Jul 14 2022 ...EVENING UPDATE... No significant changes anticipated to going forecast. Convection is slowly transitioning offshore, and hourly PoPs are trending in the right direction. 00z HRRR agrees in keeping most of the overnight hours dry until moisture surges northward again toward sunrise, before heading back southward again tomorrow afternoon. 00z LIX precipitable water of 2.15 inches is an increase of about a quarter inch over the last several flights, and is a bit above the 90th percentile climatologically. Overnight low forecast might be a degree or two too cool, but at this point, we still have time to reach those numbers if we can lose the cirrus deck. There will probably be a ZFP update later this evening to deal with temporal wording (this evening and after midnight), but general trends are very likely to be unchanged. 35 && .PREV DISCUSSION... /issued 402 PM CDT Thu Jul 14 2022/ SHORT TERM (This afternoon through Friday Night)... Mid to late this afternoon, spotty convection continues to develop generally across central portions of the CWA or generally along or near the I-10/12 corridor. The potential for convective initiation was discussed in the morning mesoanalysis update given better destabilization over central/southern areas with slow/steady increase or northward drift in motion expected this afternoon. This delay was moreso rooted from residual cirrus/anvil canopy from a decayed MCS to our west, as well as left over CIN/subsidence from convection last night but since then, convective turnover has led to surface temperatures starting to or surpassing convective temperature owing in increasing coverage. This higher coverage is due to a slight surge northwards in higher PW`s at and above 2.0" as well as a subtle deformation zone remaining in place aloft. Mean storm motion varies depending on where you are in the CWA, more from the southwest over coastal SE LA to nearly northerly over northern areas but the general average is very light and variable meaning storms developing diurnally will be very slow to move, and additional propagation or any movement will be determined by complex boundary motions/interactions. Localized flash flooding will continue to be the main risk this afternoon. Noted earlier, almost all recent hourly runs of the HRRR continues convection into the evening hours perhaps into the 7PM to 9PM hours. Coverage will be determined if convection can become deep enough to develop local cold pooling, but storms will likely remain clustered/messy with all areas becoming drier towards midnight. Conditions continue calm Friday morning with reforming storms over marine areas. Also, could see some local/patchy fog in a few isolated areas that saw heaviest rain north of I-10/12 and have included this mention for a few hours in the forecast. Otherwise, no major changes in the state of the atmosphere tomorrow other than the corridor of higher PW`s begins to sag back to the south a bit more, focusing greater heavy rain/flooding potential along and south of I-10/12 to the coast. This is in response to northerly flow attempting to "push" south as strong ridging out west begins to bulge east a bit more, compressing the deformation aloft into more of a stretched area of vorticity (due to the horizontal shearing of moist southwesterly flow meeting northerly flow from the north). So expect the dynamic support once again in conjunction with high PW`s to support additional an additional flash flooding risk tomorrow, but will be more confined to southern areas. With this southward push of mid-level flow, we could see dry air bleeding south enough to entrain with diurnal convection. HRRR soundings for across the I-10/12 corridor does spike up around 1000-1200J/kg DCAPE with THI in the low to mid 30`s leading to some sub-severe downburst potential (30-40mph range on average) but will continue to message excessive rain rates leading to flash flooding as the main risks, as mean storm flow remains very weak especially aided by higher PW closer to the coast. KLG LONG TERM (Saturday through Thursday)... Going into the weekend, an upper-level low centered over the Florida Peninsula continues to drift northwest underneath a general H5 weakness aloft towards the northern Gulf coast states. This low will steadily weaken, but continue to aid in higher convective coverage potential. Additionally, with northerly flow aloft taking over in the mid to upper-levels, upstream impulses of energy may need to be watched originating over the northern Plains to Midwestern states, sliding south. Just a bit early to depict small(meso)-scale systems this far in advance and where they may end up, but this pattern hints at the possibility of clusters or an MCS riding south along the eastern periphery of the ridge centered to the west. Will keep PoPs higher into the weekend but not very high until short-range guidance can initialize this potential with time. Thereafter going into next week, we become more under the influence of a weak positively tilted trough axis diving southeast into the MS valley region all within the same weakness region over the SE US. This will continue to support ongoing daily afternoon shower/storm chances just about each day, with the potential for better coverage mid-week. Some guidance late-week is hinting at a slow return with the summer heat, but am slow to jump on this idea full swing for now with weak flow aloft helping to keep storm chances going. Regardless, heat indicies begin to approach Heat Advisory criteria so will just need to be watched to identify changes in long-range trends as we get closer. KLG AVIATION (18Z TAF DISCUSSION)... Recent radar imagery valid around 1730Z indicates scattered SHRA/TSRA beginning to develop near and south of the I-10/12 corridor, which will continue to increase in coverage through the rest of the afternoon and early evening hours. Main impacts in any one storm will be periodic lower VIS from heavy rain and low CIGs temporarily reducing flight categories. Can`t rule out gusty, erratic downdraft winds today in any stronger storm that develops as storms today will likely produce outflow boundaries leading to quick, sudden surface to low-level wind speed and directional changes. Otherwise, expect VFR conditions outside of any of this activity. Scattered showers and storms will persist into the evening hours to atleast 0100 to 0300Z before diminishing later tonight. Due to the expected widespread nature of showers and storms today, some patchy areas of fog will be possible around daybreak generally for northern terminals, including KMCB and have included the possibility in the TAF for now. KLG MARINE... Scattered shower and storm chances will remain daily through the weekend and into parts of next week, with better coverage potential in the morning hours. Any one stronger storm could contain gusty, erratic downdraft winds >34kts, waterspouts and locally enhanced waves and seas. Outside of any showers or storms, conditions will remain mostly calm with light winds and wave/seas. KLG && .PRELIMINARY POINT TEMPS/POPS... MCB 71 91 71 91 / 30 60 10 30 BTR 73 92 74 93 / 30 70 10 50 ASD 73 92 73 91 / 40 70 20 50 MSY 77 89 76 90 / 40 80 30 60 GPT 75 89 74 89 / 50 70 30 50 PQL 73 87 74 88 / 50 70 30 60 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$
Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
839 PM PDT Thu Jul 14 2022 .SYNOPSIS...14/1225 PM. High pressure will continue to bring very warm temperatures across inland valleys, mountains, and deserts through Sunday. Coastal areas will remain cool and cloudy at times. There will be clouds over the San Gabriel Mountains each afternoon with a slight chance of thunderstorms on Friday. After minor relief on Monday, temperatures for interior sections will heat up again next week. && .SHORT TERM (THU-SUN)...14/836 PM. ***UPDATE*** The eastern Antelope Valley had quite an afternoon with a few pop-up thunderstorms developing thanks to the monsoonal flow. These storms were very short-lived and collapsed on themselves, but produced several lightning strikes. There are very few rain gauges in that area to determine how much (if any) rainfall hit the ground from each cell. However, there was a gauge at Lake Los Angeles that recorded just under a half inch from a cell late this afternoon! The bulk of the thunderstorm activity remained to our east, as expected. Thunderstorm activity has tapered off for the evening, but some cumulus clouds are still moving from south to north over the Antelope Valley and eastern San Gabriels. The big question of the night will be the stratus coverage. The marine layer is around 900 feet deep early this evening and low clouds are hovering over the immediate Ventura County coastline and across much of the coastal waters south of the Channel Islands. Expecting low clouds to blanket all the coastal areas overnight, but low confidence on the exact timing. Although with the ridge building from the east, it could foil the stratus coverage. A LAX-DAG gradient of near +6 mb has been assisting in generating gusty winds across the Antelope Valley this evening. Lake Palmdale is gusting around 40 mph, and other areas closer to 25-35 mph. Winds should taper off a little later this evening. Friday will be a very similar day to today. It will be another very warm day across the interior while the coastal areas will be moderated by the cooler marine air. Have adjusted high temperatures a bit higher based on the highs today. Lancaster reached 107 today, so there is no reason why that wouldn`t happen again Friday with this persistent pattern. Heights and thicknesses will rise a bit, so there is a chance it may be hotter. Coastal areas will likely be a bit warmer in today with the higher heights, but onshore flow will still limit the warming. With the pattern remaining very similar, there is also another possibility of monsoon thunderstorms over the eastern Antelope Valley and eastern San Gabriels. Looking at the latest guidance, both deterministic and ensemble, moisture and instability don`t look as good as they looked today. However, both the HRRR and HREF indicate cells developing just to our east, and is certainly possible that they could in reality develop in our area. So will keep the slight chance of thunderstorms in the forecast. ***From Previous Discussion*** A large high pressure dome over the entire Southwest will continue to generate very warm temperatures for our inland areas through Saturday with only minor cooling on Sunday. Heights near 594dm slide eastward on Sunday when a weak low pressure system moves into the Pacific Northwest. Until then, expect temperatures to continue to increase a couple of degrees with Saturday being the hottest day with 105 at Paso Robles and 106 at Lancaster expected. Still expect upper 90s to lower 100s in the warmest San Fernando Valley and Santa Clarita Valley region the next two days. Kept the coasts much cooler due to a persistent 7mb onshore pressure gradient and some beaches not clearing on a daily basis. Overall, NBM temperatures are doing the best and in this pattern expect a good outcome with it`s capability to handle the warmer inland values. Just trimmed the coasts back a little bit. Based on the latest forecast temperatures, we do not reach any heat product levels through the weekend and this is our warmest climatology time of the year for inland sites. The other issue in the short term is the monsoon moisture plume and any convective threat. Friday now appears to be the main day for a little more widespread thunderstorm activity across the San Gabriels and AV. HREF members have been showing cells forming in this area tomorrow with stronger instability parameters as well. Small hail and gusty winds will be a threat and even very heavy rain if cells stall or reform over the same areas. Winds turn slightly more southwest on Saturday and current short term models do not indicate any precip, so have decreased POPs over the weekend and only expect afternoon cumulus over the mountains. .LONG TERM (MON-THU)...14/207 PM. Monday will continue to be a lull in the temperature pattern as the northern Rockies low pressure system slides eastward and 500mb heights remain around 592dm for southern CA. The northern trough actually acts as a catalyst for the high pressure dome to rebuild westward quickly next week. All deterministic and ensemble data supports this idea with heights building again over southern CA beginning Tuesday. This really looks like a repeat weather situation next week from what we are currently experiencing. Inland valleys, mountains, and deserts will heat up again with many highs well into the 90s and some lower 100s possible Tuesday through Thursday. West of the mountains there will be daily onshore pressure gradients keeping low clouds near the beaches and cool daytime temperatures. Monsoon moisture will be "around" next week, but it`s very difficult to determine any significant mechanism to trigger convection in our counties. The best monsoon axis will remain to the east of our region, however, this always bears watching in this pattern and it remains the best time of the year to see this activity. && .AVIATION...15/0009Z. At 2344Z at KLAX, the marine layer was 800 feet deep. The top of the inversion was around 3600 feet at a temperature of 27 C. High confidence in valley and desert TAFs. Low to moderate confidence in coastal TAFs with lowest confidence in timing of cig arrival which may be off by +/- 2 hours. Cig heights may be off by +/- 200 feet. There is a 30% chance of LIFR conditions at KSMO and KLAX after 08Z, and a 40% chance cigs do not lift to MVFR. KLAX...Moderate confidence in TAF. Low clouds may be delayed until 05Z. There is a 30% chance of OVC004 after 08Z, and a 40% chance of cigs not lifting to MVFR. Very good confidence an east wind component will be less than 5 kt. KBUR...High confidence in TAF. && .MARINE...14/829 PM. For the Outer Waters, moderate to high confidence in current forecast. A Gale Warning has been issued through late tonight for the northernmost section, with gusts up to 40 knots expected. There is a 40% chance of additional Gales Friday night in this area. For PZZ673, high confidence in Small Craft Advisory (SCA) level winds through at least Saturday night. For Sunday through Tuesday, there is a 50% chance of SCA level winds across both the northern zones. For PZZ676, moderate confidence in current forecast with a 20%-30% chance of SCA level winds through Friday then a 50% chance of SCA level winds at times Saturday through Tuesday especially NW of San Nicolas Island. For the Inner Waters north of Point Sal, moderate confidence in current forecast. There is a 30-40% chance of SCA level winds at times mainly in the in the afternoon and evening hours through Tuesday. For the Inner Waters south of Point Conception, high confidence in current forecast as winds and seas are expected to remain below SCA levels through Tuesday. && .BEACHES...14/151 PM. The July full moon, which occurred this morning, will bring high astronomical tides to southern California beaches through this evening. Minor tidal overflows or coastal flooding could result at some low lying beaches in Los Angeles and Ventura Counties. Elevated high tides between 7.1 and 7.3 feet are expected to occur late this evening. A BEACH HAZARDS STATEMENT for minor tidal overflow is in effect thru late this evening for the aforementioned beaches. In addition, a long-period southerly swell will continue across the waters through this evening which could enhance the chances of minor coastal flooding and bring a high rip current risk to southern California beaches. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement in effect until midnight PDT tonight for zones 87-354-362-364. (See LAXCFWLOX). PZ...Gale Warning in effect until 3 AM PDT Friday for zone 670. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Sunday for zone 673. (See LAXMWWLOX). && $$ PUBLIC...Stewart/EB AVIATION...Stewart MARINE...Sirard/Smith BEACHES...Sirard SYNOPSIS...EB Experimental Graphical Hazardous Weather Outlook at:
Area Forecast Discussion
National Weather Service Nashville TN
748 PM CDT Thu Jul 14 2022 ...New UPDATE... .UPDATE... Issued at 744 PM CDT Thu Jul 14 2022 Radar continues to show some showers across our northeast zones that have moved southward out of Kentucky. This activity is occurring along a weak boundary that has been enough to keep this activity going despite the lower moisture in our area versus further north. HRRR suggests activity will continue another couple of hours before dissipating and have expanded slight chance pops southward and westward accordingly. It`s not out of the question a few more showers could pop up as far west as the I-65 corridor where visible satellite shows some taller cumulus. Made some other minor adjustments to various grids but nothing significant. && .SHORT TERM... (This afternoon through Friday Night) Issued at 210 PM CDT Thu Jul 14 2022 Middle Tennessee is dealing with a scattered Cu field and temperatures in the mid 80s to lower 90s this afternoon. There are a few showers in central Kentucky diving southward, but are tending to fall apart as they get further south. To be safe, a small slight chance PoP was added along the border for the far eastern quarter. Some patchy fog can be expected to develop again after midnight and will mix out quickly Friday morning. The area will continue to be on the eastern influences of the large central US upper ridge on Friday which will give us another warm day with manageable humidity levels. && .LONG TERM... (Saturday through next Thursday) Issued at 210 PM CDT Thu Jul 14 2022 The upper ridge will begin to retreat westward on Saturday which could allow an isolated storm or two mainly along the plateau. A deepening upper trough will round the top of the ridge Saturday into Sunday with the entire area under troughing influences by Sunday. This will allow for scattered showers and storms Sunday and Sunday night. Some of the activity will likely fall off Sunday night due to diurnal influences, but with the trough axis still west of the area, some activity Sunday night seems reasonable. Storm chances continue on Monday before the trough axis clears the area Monday night. Behind it, the upper ridge will try to expand eastward once again. High temperatures will climb back into the mid 90s by Tuesday and likely stay there the rest of the work week. && .AVIATION... (00Z TAFS) Issued at 653 PM CDT Thu Jul 14 2022 Scattered cu and light winds will continue for a few hours this evening. Isolated showers are dwindling and should have no impact on terminals. Expect winds to go calm overnight, then grow light again during the daytime hours on Friday. VFR conditions will prevail throughout the period. && .PRELIMINARY POINT TEMPS/POPS... Nashville 70 93 71 95 / 10 0 0 10 Clarksville 67 93 70 95 / 0 0 0 10 Crossville 63 85 65 87 / 20 0 0 10 Columbia 67 93 68 94 / 0 0 0 10 Cookeville 66 88 67 90 / 20 0 0 10 Jamestown 62 85 65 88 / 20 0 0 10 Lawrenceburg 66 92 68 93 / 0 0 0 10 Murfreesboro 67 93 68 95 / 10 0 0 10 Waverly 68 94 71 96 / 0 0 0 0 && .OHX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......Shamburger SHORT TERM...Reagan LONG TERM....Reagan AVIATION.....Whitehead
Area Forecast Discussion...Updated
National Weather Service Pendleton OR
450 PM PDT Thu Jul 14 2022 Updated aviation discussion .SHORT TERM... Tonight through Saturday night... The two main weather features of note in the short-term period will be a potential for isolated thunderstorms this evening into early Friday morning across central Oregon and the eastern Mountains, and breezy to windy conditions near the Cascade gap areas Friday afternoon. The latter, in combination with low relative humidity(RH), likely provides elevated fire weather concerns for parts of the region with a Fire Weather Watch issued for the affected areas. Otherwise, the remainder of the period looks rather benign with near normal conditions for mid-July. An upper-level shortwave trough embedded in broad SW flow over the Pacific Northwest will cut straight through the CWA tonight. There appears to be more than enough upper-level forcing to initiate convection just ahead of this wave feature however the marginal mid- level moisture and elevated instability doesn’t appear conducive to anything more than isolated showers and T-storms. Convective allowing models like the HRRR and HREF ensemble aren`t indicating much activity, limiting formation to central Oregon this evening and to our east in Idaho early Friday morning. However, the HRRR and HREF have struggled as of late with the placement of nocturnal high based convection. Low-end PoPs/T-storm chances were adjusted to match an area of overlap between the best 700-500mb moisture and instability in an field of good forcing just ahead of the shortwave. This area will extend to the eastern Mountains into portions of the SE Columbia Basin overnight. These locations outside of central Oregon are only other spots that may see isolated T-storms form, if at all; confidence is rather low. Fortunately this feature progresses quickly, moving out of the CWA by early to mid Friday morning. Our attention then turns to Friday afternoon when breezy conditions likely develop. Unperturbed southwesterly flow resides over the Pacific Northwest Friday into Friday night however surface pressure gradients across the Cascades increase as the day progresses, leading to breezy gap winds developing as early the late morning/midday. Both the GFS and NAM project a roughly 6.5-8.5mb cross Cascade pressure gradient between KSEA and KMWH at its peak in the late afternoon hours. This should be enough to facilitate projected 10-20mph sustained winds with 30-40mph gusts in the Cascade gap areas like the Kittitas Valley and Columbia Gorge/Simcoe Highlands. While not necessarily impressive values, low RH in the Columbia Basin will make for elevated fire weather concerns where the winds are able to infiltrate further east of the gaps. Some uncertainty exits as to whether Red Flag criteria winds extend far enough east to justify a Red Flag Warning at this time. So, have opted instead to issue a Fire Weather Watch for a part of the western Columbia Basin near the east end of the Gorge, and the southern Kittitas Valley Friday afternoon and early evening. Winds lighten later Friday evening and RH recovers overnight. Otherwise, dry conditions continue Saturday into Saturday night. Winds again look breezy Saturday afternoon in similar locations however RH appears higher than the day prior so fire weather concerns won`t be as elevated. Schuldt/99 .LONG TERM...Sunday through Thursday... The extended period will be characterized by mostly dry and near- to above-normal temperatures. Moreover, breezy afternoon winds through the Cascade gaps into the Columbia Basin are expected, especially Sunday. Additionally, widespread minimum RH values between 10 and 25 percent are forecast each afternoon for eligible fire weather zones, and coincident critical wind and RH thresholds look possible, primarily on Sunday. 12Z ensemble guidance is coming into substantially better agreement compared to previous runs regarding an incoming closed upper-level low Sunday, though some timing and location differences are still apparent. While precipitation chances look low, and the main energy stays in Washington, the primary concern will be widespread breezy to windy west winds, especially through the Cascade gaps as winds aloft and surface pressure gradients strengthen. These breezy winds may also infiltrate as far as the foothills of the Blue Mountains. Following the exit of the closed upper low on Monday, guidance begins to diverge again on details of the pattern. In general, ensemble means show a return to southwest flow aloft. Instability and moisture is lacking so, despite the typically favorable southwest flow, currently not excited about any widespread convection. However, a minority of ensemble members are hinting at a couple of compact vorticity maxima ejecting across our CWA Wednesday afternoon and Thursday afternoon. This pattern is also suggested by the 12Z ECMWF deterministic run. Should this solution materialize, chances of convection will certainly be higher given the synoptic forcing. Plunkett/86 && .AVIATION...00Z TAFs...VFR conditions are expected through the period with diurnally driven winds generating afternoon gusts of 15- 25 kts for DLS, BDN, and RDM for the next few hours this evening and again for the same sites with the addition of PDT after 20Z tomorrow. Skies will be mostly clear but a passing disturbance will bring some mid-level clouds and perhaps some high-based showers initiating over the Cascade crest into central Oregon between 03Z- 12Z then crossing along the Blue Mountains from 06Z-15Z before moving east of the area. There appears to be a low chance of light showers and widely isolated thunderstorms with this disturbance, possibly affecting BDN and RDM first then later on ALW and PDT. Due to the low probability and confidence of this occurring, have omitted any mention of showers or thunderstorms from the TAFs for those sites and just have FEW-SCT at 100-120. Perry/83 && .PRELIMINARY POINT TEMPS/POPS... PDT 61 92 60 91 / 20 20 0 0 ALW 63 95 62 94 / 20 20 0 0 PSC 65 98 65 96 / 10 10 0 0 YKM 58 94 57 92 / 0 0 0 0 HRI 62 96 61 94 / 20 10 0 0 ELN 57 90 58 88 / 0 0 0 0 RDM 53 89 51 89 / 20 10 0 0 LGD 59 89 57 89 / 10 20 0 0 GCD 55 93 54 94 / 10 10 0 0 DLS 60 90 60 88 / 10 10 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Fire Weather Watch from Friday afternoon through Friday evening for ORZ641. WA...Fire Weather Watch from Friday afternoon through Friday evening for WAZ690-691. && $$ SHORT TERM...99 LONG TERM....86 AVIATION...83
Area Forecast Discussion
National Weather Service Phoenix AZ
455 PM MST Thu Jul 14 2022 .UPDATE...Updated Aviation Discussion. .SYNOPSIS... Above normal temperatures will persist through at least early next week with highs reaching 110 degrees or better across most lower desert locations through Sunday and just below 110 degrees starting Monday. Moisture has improved over much of the area which will allow for better shower and thunderstorm chances through the upcoming weekend. Storms will be most prevalent and concentrated over south-central Arizona and higher terrain areas, with today and Sunday potentially seeing the most widespread storm activity. && .DISCUSSION... Early afternoon satellite shows widespread thunderstorms across northern AZ, which developed fairly early this morning in a very unstable airmass. Convection across southern AZ has been a little slower to respond with lower overall instability as thermodynamic profiles above the boundary layer are more moist adiabatic, but convection has begun bubbling up. The robust convection over northern AZ is slowly building south with southward-moving outflow boundaries. Whether these outflows continue to generate new convection as they propagate further into the lower deserts this afternoon and evening remains to be seen. RAP soundings in Phoenix are still showing the environment is capped, which is evident with the lack of convective CU. However, mesoanalysis is depicting up to 1000-1500 J/kg SBCAPE. So, it will come down to whether the outflows are strong/deep enough to overcome the cap. Hi-res CAMs do support more robust development eventually this afternoon down in Pima and parts of Pinal county. Any colliding outflows from convection to the north with that to the south will certainly help overall chances at lower elevations. The environment is still supportive of strong to severe storm impacts with 50-70% HREF probabilities of greater than 35 mph convective winds. DCAPE values are upwards of 1500 J/kg. Blowing dust will be a concern again later this afternoon, especially in the prone areas like western Pinal county. Mean winds are a little stronger today, compared to yesterday, at 10-15 kts from the southeast. This may limit the overall flooding threat, with storms less likely to linger in one spot. However, decent rain rates up to 1 inch or higher will still be possible with the deeper moisture profiles. So, flash flooding will still be possible, especially with any training of storms. Most hi-res models show at least isolated convection continuing into the overnight hours with a weak wave embedded in the southeast flow. NBM PoPs remain around 20-25% through midnight before gradually dropping off. Buoyancy will be lower during the overnight hours, thus impacts will not be as great with any showers or storms. Any activity should wane before or shortly after sunrise Friday. .PREVIOUS DISCUSSION... Starting Friday, further complexities will be added to the storm outlook as drier air will start to work into eastern Arizona from New Mexico, but the upper levels are likely to become even more supportive for storms by Friday night as an easterly upper level inverted trough tracks through northern Mexico, just clipping southern Arizona. Current forecast thinking is that Friday may see more limited storm activity due to the drier air and the potential for a somewhat worked over atmosphere from today`s activity. The HREF generally supports less storm coverage on Friday, but also a westward expansion in the storm potential as instability increases across southeast California. The influence of the upper level disturbance is likely the biggest unknown going into Friday night and then through the rest of the weekend as winds aloft are forecast to increase across the region. Drier air is still seen impacting far eastern Arizona through the weekend, but areas west of a Tucson to Gila County line are still likely to have enough moisture for daily chances for storms. The best upper level support seems to fall on Sunday, so as long as moisture is sufficient, Sunday may be a more favored day for storm activity. Looking at early next week, the pattern is likely to shift again as we seem to lose upper level support, but could see a moisture increase out of Mexico. Either way, it seems likely we will see at least a slight chance of storms each day through early next week. Very warm temperatures will remain a concern through at least the weekend with H5 heights of 593-597dm persisting over the region. NBM forecast highs of 110-114 degrees are mostly seen across the Arizona lower deserts through Sunday, while southeast California is expected to peak mostly in a 112-116 degree range Friday- Sunday. These forecast temperatures show enough High HeatRisk across the western half of Imperial County for us to issue an Excessive Heat Warning Friday through Sunday. Some slight relief from the heat is likely for next week as NBM guidance shows high temperatures dropping just below 110 degrees starting Monday. && .AVIATION...Updated at 2355Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Main aviation weather concern remains the potential for gusty outflow winds as well as thunderstorms near area terminals this evening. Expecting an initial switch to northerly over next hour or less as outflows from storms over Yavapai County move into the metro. Another switch to more easterly outflows is anticipated around 03Z as outflows from storms further to the east and southeast move into the region. Still uncertainty as far as the direction will be with this 03Z switch, depending on which exact outflows become dominant as they move into the Phoenix metro. The TS themselves will likely move close enough to include VCTS at all locations and cigs down to about BKN120. However, chances for storms actually impacting the terminals is less (20-30%). Most storms will dissipate after 05z with some lingering mid level cigs prevailing and winds becoming more typical easterly. A earlier-than-usual switch is once again forecast for Friday with chances for TS returning Friday evening. At this point, confidence is too low to put anything more than VCTS and a wind shift to easterly is the TAFS as this point. Southeast California/Southwest Arizona including KIPL and KBLH: Winds at KIPL will favor a southeasterly component while winds at KBLH will favor a southerly component through the TAF period. Wind speeds to remain aob 10 kts for the most part with some afternoon breeziness at times, especially at KBLH. Otherwise, expect FEW-SCT clouds aoa 15 kft. && .FIRE WEATHER... Daily shower and thunderstorm chances, generally 20-40% each day, are expected over the Arizona high terrain through early next week, while chances (10-30%) will expand westward over the lower deserts through Friday. The main threats from the mainly afternoon/evening thunderstorms will be lightning, strong outflow winds, and locally heavy rainfall. Modest moisture levels will keep minimum afternoon humidities mostly to between 15-20% across the lower deserts to upwards of 25% over higher terrain areas. Wetting rainfall chances will remain fairly low with daily chances 5-15% for the lower deserts to upwards of 15- 25% over higher terrain areas. Winds will generally follow diurnal patterns with some enhanced upslope afternoon breeziness common most days. Above normal temperatures will persist through at least the weekend with daily readings 3-6 degrees above normal. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...Excessive Heat Warning from 10 AM Friday to 8 PM PDT Sunday for CAZ562-563-566-567. && $$ DISCUSSION...Benedict PREVIOUS DISCUSSION...Kuhlman AVIATION...Frieders FIRE WEATHER...Kuhlman
Area Forecast Discussion
National Weather Service Reno NV
227 PM PDT Thu Jul 14 2022 .SYNOPSIS... Temperatures will remain above average into early next week, with some of the lower elevations possibly reaching the century mark. Typical afternoon Zephyr breezes are expected, along with isolated thunderstorms, each afternoon and evening. && .SHORT TERM... The synoptic pattern over the next couple of days will favor the development of typical afternoon zephyr breezes with some slight enhancement north of Interstate 80, isolated afternoon/evening thunderstorms, continued heat, and transport of smoke downwind of the Washburn fire. An upper-level trough begins to push northwestward away from our area, while an area of high pressure builds northwestward from the Four Corners. Thunderstorms: * We`re already seeing some towering cumulus building across southern Mono and Mineral counties this afternoon. Moist mid- level flow will continue to push northward around the periphery of the aforementioned upper-level ridge over the Four Corners into southern Mono and Mineral counties this afternoon. Modest mid-level moisture (0.5-0.6" PWATs) with orographic convergence along the White Mountains and the Eastern Sierra may help to generate some isolated thunderstorms (10-15% chance). Due to the very high-based nature of the cloud bases and the deep, dry sub-cloud layers, any thunderstorms that do form will be capable of producing cloud-to-ground lightning outside of cores. The main concerns will be gusty and erratic winds to 50 mph, blowing dust, brief heavy rainfall, and deadly cloud-to-ground lightning. For more information with regards to concerns to fire partners, please see the fire weather discussion below. * Thunderstorm chances increase Friday (15-30%) as the ridge continues to push more into western Nevada and the Sierra, bringing more monsoonal mid-level moisture into the area. Mountaintop convergence due to daytime heating should allow storms to initiate along the higher terrain of the central- southern Sierra and western Nevada as far north as Interstate 80 and east toward Austin. The main hazards will be gusty and erratic winds to 50 mph, possible blowing dust, brief heavy rainfall, and cloud-to-ground lightning. Fire starts will once again be another concern. Winds: * Another couple of afternoons of modest southwesterly flow are expected over the Sierra and western Nevada. We`ll see gusts of 25-30 mph areawide, with stronger gusts to 35 mph north of Interstate 80. Friday, we`ll see a similar situation with gusts of 20-30 mph areawide, with stronger gusts across northeast California and northwestern Nevada. Heat: * Temperatures will remain above normal but only a few degrees warmer than our normal highs. Highs across Sierra valleys are expected to be in the mid-to-upper 80s and upper 90s across the lower elevations. Smoke: * The Washburn fire in Yosemite National Park continues to eject smoke and haze into the low-mid atmosphere this afternoon. Several Alert Wildfire cameras show this smoke affecting areas as far north as Bridgeport, the Carson Valley, and Mason Valley. Smoke will stay concentrated across northern Mono County, southern Alpine County, Douglas County, southern Lyon County, and western Mineral County tonight. Friday, smoke looks to be consolidated in these areas once again, with some of it pushing farther south to near Lee Vining. We will continue to see degraded air quality in these areas as well as lofted smoke, which will create hazy conditions each afternoon as long as the fire continues to burn. Please see for current air quality conditions in your area. -Johnston .LONG TERM...Saturday Onward... * Main trend we`re seeing in NBM and ensemble guidance is that dry southwest flow looks to be winning out from Tahoe-Reno northward limiting t-storm coverage. But "limiting" most definitely doesn`t mean zero. Plenty of ECMWF ensemble members bring sufficient precipitable water northward and that coupled with zephyr or mountain convergence zones could certainly kick off some isolated storms each day from Reno-Tahoe-I-80 and northward. Probabilities from NBM suggest 5-15% each afternoon. * More consistent daily t-storm chances exist for the Eastern Sierra, Mineral Co, and as far north as the Pine Nuts in W Nevada. This is the area with higher confidence in sufficient moisture, heating, and instability each day. NBM guidance has roughly 20-30% t-storm POPs in these areas which makes sense given the nearly unanimous ECMWF ensemble precipitable water increases. * All impacts are on the table ranging from lightning and new fire starts to pockets of heavy rain and hail. Strong outflow winds are almost a guarantee with afternoon humidity in the teens yielding inverted-v soundings. Anyone with outdoor plans should be prepared for rapid changes in weather with t-storms. SW flow pattern would push any storms off the high Sierra crest to the NE, so there will be a tight gradient in POP from the west to east side of the Sierra. * Temperatures will remain warm, but not excessively so and within the margin of error for what we`d expect in mid-July. Saturday and Sunday are the hottest days of the long term with a good bet for near or just above 100 in many W Nevada locations and solid 80s for mountain communities. Typical zephyr breezes to 30 mph are projected each afternoon and early evening. This can serve as a trigger for isolated t-storms further north than current model guidance indicates, along with creating brief localized critical fire weather areas each afternoon. -Chris && .AVIATION... * Smoke: With SW flow continuing, smoke and haze from the fire near Yosemite will impact some areas east of the Sierra crest. Latest HRRR Smoke model shows Bridgeport (O57) to Hawthorne (HTH) having the highest chance of MVFR or worse conditions in smoke along with terrain obscuration. There`s some chance of mainly VFR haze filtering northward into TVL, CXP, MEV areas with night/morning drainage winds. * Thunderstorms: Moisture aloft will start to increase today but more so Friday into the weekend to allow for increasing coverage and northward extent of t-storms along the Sierra east side into W Nevada. For today, risk is quite confined to mainly MMH-HTH-BIH region and latest HREF showing only about a 10-15% chance in that zone 22z-02z today. For Friday afternoon-evening, the risk of storms increases in that MMH-HTH-BIH zone to about 30% with also storms possible further north to Bridgeport, Yerington, and Fallon (10-20%). Typical impacts: brief MVFR conditions, outflows to around 40 knots, dust, and of course lightning. Drier southwest flow seems to win out Friday over Tahoe, Reno, CXP areas yielding minimal risk of storms, but that may change Saturday and/or Sunday per NBM guidance. -Chris && .FIRE WEATHER... Winds/RH: * We`ll see continued dry (humidity in the teens and single digits) and breezy southwest winds today, with gusts reaching as high as 30 mph this afternoon. Farther north across far northwestern Nevada and northeastern California, we`ll see some enhancement in these winds with gusts as high as 35 mph expected. A few hours of critical conditions are expected in eastern Lassen County, the northern Sierra Front, and northern Washoe County. Poor overnight RH recovery is expected once again across the region. * Friday, southwest-west afternoon breezes (gusts 25-30 mph) are once again expected, with stronger gusts to 30-35 mph north of Interstate 80. Humidity will remain lower north of Interstate 80 (single digits and teens) and begin to slightly creep up at least 5-8% south of Interstate 80 as monsoon moisture begins to push north. Isolated thunderstorms: * A ridge of high pressure centered over the Four Corners will build northwestward into the region allowing a corridor of mid- level moisture to push into southern Mono and Mineral counties (PWATs ~0.5"), creating an isolated chance for thunderstorms in these areas (10-15% chance). Very dry and deep sub-cloud layers with inverted-v profiles extending up to 600 mb in altitude will support smaller cores with the potential for dry lightning and new fire starts. Any outflows that push away from thunderstorms could create wind gusts as high as 45-50 mph. * Additional storms are possible (15-25% chance) Friday into the weekend as moisture increases across the region. Storms look to be more hybrid (mix of wet and dry) with lightning starts and gusty outflow winds being the main concerns. -Johnston && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit...