Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/29/23


Area Forecast Discussion
National Weather Service Austin/San Antonio TX
916 PM CDT Fri Apr 28 2023 ...New UPDATE... .UPDATE... Issued at 916 PM CDT Fri Apr 28 2023 Showers and thunderstorms have moved out of our area into Southern Texas and the Coastal Plains. Severe storms are no longer expected and have allowed the Severe Thunderstorm Watch 179 to expire at 9 PM CDT. Have also removed or lowered POPs. However, cannot rule some lightning from the anvil of the thunderstorms to our south and southeast, as well as, some very light rain through midnight. && .UPDATE... Issued at 715 PM CDT Fri Apr 28 2023 Showers and thunderstorms continue to track to the east-southeast and at 7PM CDT are along a Giddings to San Antonio line with activity more scattered to near Cotulla and Laredo. Have removed areas west of there from the Severe Thunderstorm Watch, as well as, lowered or removed POPs as the airmass has been stabilized. Remainder of the Watch and POPs look good through 9 PM CDT as still expect large hail and damaging wind gusts. Only other changes were to reestablish trend to the sensible weather parameters. && .MESOSCALE UPDATE FOR SEVERE THUNDERSTORM WATCH 170... Severe thunderstorms have developed from Williamson County southwest to Bandera County over the last couple of hours. Activity has quickly consolidated into a southeast-advancing line, and has pushed east of downtown Austin and Williamson County. Mostly large hail has been reported with this activity, though high velocity values have been sampled sporadically from radar as well. A storm has blossomed over southeastern Bandera County over the half hour, likely producing large to very large hail. This storm has developed along the southwestern flank of the existing convective line, and finds itself in an environment uncontaminated by prior convective activity. The San Antonio Intl ACARS sounding shows 7.5-8 C/km lapse rates above the boundary layer, suggesting that the near-storm environment will continue to support explosive development and large hail potential as the storm approaches and moves over Bexar County. Severe Thunderstorm Warnings have been issued for areas north of downtown, and those along/north of I-410 should prepare immediately for large to very large hail and damaging straight line winds. Further southwest, activity linked to development along the Serranias del Burro Mountains continues to move over the Winter Garden region. This activity has been more cellular in nature, producing mostly large hail reports over the last 2 hours. Given the isolated nature of these storms, we will need to monitor for any brief isolated tornado potential, particularly in the storm currently approaching Pearsall. Large hail and damaging winds will continue to be the main hazards with these storms otherwise. && .SHORT TERM... (Tonight through Saturday night) Issued at 146 PM CDT Fri Apr 28 2023 ...Key Messages... * A line of storms will develop across the Hill Country by around 4PM, move eastward across the I-35 corridor between 6-8PM, and into the Coastal Plains from 8PM-11PM. * There is a level 3 of 5 risk for severe storms along this line. Scattered to numerous instances of damaging straight-line wind gusts and large to very large hail possible. Isolated tornado also possible. * While the speed of the system will prevent a widespread heavy rainfall threat, some isolated pockets of quick flooding are possible near and east of I-35 where more intense rainfall rates could occur. * Remain weather aware this afternoon and evening. Given the potential timing of storms during the late afternoon into the Friday evening commute, those with travel plans should pay close attention to the radar and any potential watches and warnings. The morning low stratus and patchy fog with the ongoing moisture advection has mixed out into the afternoon with mostly sunny skies now across the region. Temperatures have quickly warmed and will continue to do so through the mid-afternoon. This will continue to aid in the atmosphere becoming increasingly unstable ahead of the approach of a strong front and the potent parent upper level low pressure system. This will lead into the risk for severe storms that is highlighted below. Some discrete convection remains on target to develop just to the north of the region starting mid-afternoon, near a triple point and south along a dryline. The CAMs remain in strong agreement that convection will unzip southwest into the Hill Country late afternoon and eventually into an MCS near the I-35 corridor early this evening, where a strong pool of instability resides. With steep elevated lapse rates overspreading the region, MLCAPE values are indicated to be on the order of 3000-3500 J/kg, in a region of 0-6KM bulk shear values of around 50 kt. This supports a severe threat of initially large to very large hail where the storms first unzip late this afternoon, transitioning to a damaging straight-line wind threat into and to the east of the I-35 corridor. SPC highlights the majority of the region in a level 3 of 5 (Enhanced) for severe storms with the potential in some isolated intense storms of hail 2+ inches in diameter and bowing segments of 75+ mph or greater. The low-level shear profiles and hodographs may also be enough to where an isolated tornado threat may be possible as well. While this is a lower confident hazard compared to the large hail and damaging wind threat, it could materialize if the updraft/downdraft convergence zone can remain balanced and any local surges take place orienting more line-normal to the better 0-3KM bulk shear vectors. The storms as they advance into and across the coastal plains could become undercut by the forward propagating front and/or outflow but latest CAM guidance has become less inclined of this happening compared to earlier runs. Due to the speed of the system, widespread heavy rainfall is not expected. Nevertheless, some pockets of more intense rainfall rates could lead to an isolated flash flooding threat near and east of the I-35 corridor. On average, rainfall amounts west of the I-35 corridor counties is expected to remain around or less than 1/4 of an inch. Along and east of I-35 rainfall amounts of 1/2 to 1 1/2 inches are forecast, with a few pockets of 2-3 inches possible east of I-35. Behind the cold front, windy conditions will also be expected to develop from out of the north-northwest with gusts of 35 to 45 mph possible this evening across the Southern Edwards Plateau and western Hill Country this evening. A Wind Advisory will be issued across these areas from 00Z to 06Z. Breezy conditions are expected elsewhere from this evening into tonight before winds start to uptick into/through Saturday morning with daytime heating. Winds could gust again into the 35 to 45 mph range. The need for another wind advisory will be possible across a larger portion of South- Central for that secondary increase in winds. For locations to the west that could miss out on tonight`s wetting rains, elevated to near critical fire weather concerns may exist given the breezy northwesterly flow and drier air during Saturday afternoon. Becoming much cooler from tonight into Saturday behind the front, with overnight lows ranging from the upper 40s into the 50s and afternoon highs ranging from the low 70s to the low 80s along the Rio Grande. Another cool night will be in store during Saturday night as the winds slacks off with overnight lows in the mid to upper 40s and low to mid 50s. && .LONG TERM... (Sunday through Friday) Issued at 146 PM CDT Fri Apr 28 2023 Most of the long-term portion of the forecast will be rain free as upper level subsidence then upper level ridging moves into the region. This should lead to drier air at the surface which should lead to high temperatures Sunday through Wednesday in the 80s to 90s with lows in the lower 60s making pretty nice days. Dewpoints will pick back up Wednesday afternoon through the remainder of the forecast period. At the same time, a couple of weak disturbances could translate through the region bringing some low rain chances back into the forecast. The NBM keeps everything at 20 percent or less and see no reason to deviate from that at this point. Otherwise, highs Thursday and Friday will be in the upper 80s to lower 90s with lows in the upper 60s to lower 70s with the higher surface moisture. && .AVIATION... (00Z TAFS) Issued at 715 PM CDT Fri Apr 28 2023 SHRA/TSRA with restrictions to CIGs/VSBYs will continue at KSAT/KSSF through 01Z-02Z while moving away from KAUS by 01Z. Otherwise, VFR flying conditions prevail tonight through Saturday night. North to northwest winds of 15 to 25 KTs with gusts to 30 to 35 KTs prevail tonight into Saturday due to tight surface pressure gradient, then gradually decrease Saturday afternoon as the gradient slackens with a more rapid decrease Saturday evening as airmass decouples after sunset. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 54 73 51 87 / 10 0 0 0 Austin Bergstrom Intl Airport 53 73 48 84 / 10 0 0 0 New Braunfels Muni Airport 54 74 49 87 / 10 0 0 0 Burnet Muni Airport 52 72 48 87 / 10 0 0 0 Del Rio Intl Airport 57 82 54 95 / 10 0 0 0 Georgetown Muni Airport 52 71 48 84 / 10 0 0 0 Hondo Muni Airport 53 78 47 88 / 10 0 0 0 San Marcos Muni Airport 53 73 45 85 / 10 0 0 0 La Grange - Fayette Regional 55 70 47 81 / 10 0 0 0 San Antonio Intl Airport 54 76 51 86 / 10 0 0 0 Stinson Muni Airport 54 77 51 86 / 10 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... Wind Advisory until 1 AM CDT Saturday for Bandera-Edwards-Gillespie- Kendall-Kerr-Kinney-Real-Uvalde-Val Verde. && $$ Short-Term...04 Long-Term...29 Aviation...04
Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
836 PM PDT Fri Apr 28 2023 .SYNOPSIS...28/835 PM. Warm and dry conditions are expected across the interior through Sunday. Coastal areas will remain mild with persistent low clouds and locally dense fog. High temperatures will peak Saturday before rapid cooling begins on Monday, including increasing clouds and rain chances Tuesday through Thursday. && .SHORT TERM (FRI-MON)...28/832 PM. Upper level ridge of high pressure will remain over Southwest California through Saturday, then cyclonic flow develops on Sunday and Monday as an upper level low pressure system develops off the coast of northern California. Near the surface, moderate onshore flow will prevail through the period although some weak northerly offshore gradients develop Sunday evening. Satellite imagery showing low clouds and fog surging inland across the coastal plain this evening. ACARS data showing the marine layer depth around 1200 feet this evening across the LA Basin. The marine layer depth is expected to remain shallow through Saturday so inland extent of stratus/fog will be less than this morning, likely just reaching the lower coastal valleys. However, with the more shallow inversion, there will likely be some patchy dense fog tonight. For Saturday night and Sunday night, the cyclonic flow aloft and onshore surface flow will allow for the inversion to deepen and allow stratus/fog to penetrate further inland each night. Other than the stratus, there will be varying amounts of high clouds drifting overhead through Monday, so can expect mostly clear to partly cloudy conditions outside of the stratus/fog. As for temperatures, Saturday will be the warmest day through the period. Away from the coast, temperatures on Saturday will climb into the mid 80s to mid 90s, while temperatures along the coast remain noticeably cooler with continued marine influence. However for Sunday and Monday, cooler conditions can be expected for all areas as thicknesses lower and marine influence increases. .LONG TERM (TUE-FRI)...28/200 PM. For the extended, main concern will be previously mentioned upper low developing off the northern California coast on Monday. As this low moves southward, it will bring the threat of rain and high elevation snowfall to the area Tuesday through Thursday (with some light shower threat lingering into Friday). Model-wise, the deterministic models differ in the details of the track of the upper low as well as available moisture (which is to be expected this time of year). Basically, the GFS is faster and a bit further westward with the track of the low than the ECMWF. So, the GFS generates noticeably less precipitation than the ECMWF solution. Looking at the ensembles, the same story is indicated. The GFS members indicate noticeably less precipitation than the ECMWF members. So, there is high confidence in receiving measurable rainfall next week, but still low confidence in timing and amounts. Current forecast QPF is for generally 0.25-0.75 inches of rainfall with local amounts up to 1.00 inch. Looking at NBM probabilities, there is a 20-40% chance of a 1-2 inch event. So, the uncertainty remains. Snow levels look to drop to around the 4500-5500 foot range. So, there will be some measurable snowfall at the higher elevations, but confidence in amounts is still low due to the uncertainty of rainfall amounts. 500 mb temperatures are forecast to be around -25 degrees Celsius Wednesday/Thursday which means at least a non-zero chance of thunderstorms across the area. Given all the model differences, still too early to include any mention of thunderstorms, but the potential will need to be monitored over the coming days. && .AVIATION...29/0112Z. At 0105Z at KLAX, the marine layer was 1200 ft deep. The top of the inversion was at 3000 ft with a temperature of 22 C. High confidence in desert TAFs. Low to moderate confidence in remaining TAFs due to uncertainty in the marine layer cloud timing. Timing of flight cat changes may be off by up to 3 hours. At KPRB there is a 20% chance of LIFR conds from 12Z-16Z. At KSBP and KSMX there is a 40% chance for 1/4 SM from 06Z-16Z, with a 20% chance at KSBA, KOXR. and KCMA. KLAX...Moderate confidence in TAF. Timing of flight cat changes may be off by up to 3 hours. LIFR candidness likely by late evening or overnight. There is a 20% chance of 1/4SM and Vv001 conds 06Z-16Z. MVFR/IFR cigs likely to continue through Saturday afternoon. No significant east wind component expected. KBUR...Moderate confidence in TAF. There is a 20# chance of LIFR/VLIFR conditions between 12z-15Z Saturday. && .MARINE...28/834 PM. High confidence in conditions remaining below Small Craft Advisory (SCA) level for all waters through at least Saturday morning. Winds will begin to increase Saturday afternoon through early Sunday ahead of an approaching frontal system This is expected to bring strong NW winds and steep hazardous seas across most of the waters Sunday afternoon through through Monday evening. Across the waters along the Central Coast and south to San Nicolas Island there is high confidence in SCA level winds, and a 50-60% chance of Gale Force winds. For the Santa Barbara Channel, Sunday afternoon through Monday there is a 50-70% chance of SCA level winds, and a 30-40% chance of Gales. On Sunday, winds will be higher in the western portion of the Channel, and on Monday winds will be high for the entire channel. For the nearshore waters south of the Channel Islands there is moderate confidence in SCA winds on Monday with a 20-30% chance of Gales. Steep, hazardous seas will build throughout the waters, to between 9 to 12 feet over the outer waters and generally 6 to 9 feet nearshore. Late Monday night through Wednesday, decreasing winds and seas are expected. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Gale Watch in effect from Sunday morning through late Sunday night for zones 645-670. (See LAXMWWLOX). Gale Watch in effect from Sunday morning through Monday evening for zones 673-676. (See LAXMWWLOX). && $$ PUBLIC...Gomberg/Thompson AVIATION...Gomberg MARINE...Smith SYNOPSIS...Gomberg weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox
Area Forecast Discussion
National Weather Service Nashville TN
930 PM CDT Fri Apr 28 2023 ...New UPDATE... .UPDATE... Issued at 916 PM CDT Fri Apr 28 2023 Only a few changes needed to the forecast this evening. The main concern overnight is the potential for fog development. Some guidance is suggesting short periods of dense fog may be possible in the hours before sunrise (3AM to 6AM), but the main area of concern shifts from our southwestern areas to our eastern counties depending on the model. In the next few hours, we may have a better handle on where/if dense fog might develop as visibilities begin to fall. Winds have become mostly calm, which will help with fog development, but increasing cloud cover from the west might keep temperatures a touch warmer than expected...reducing the chance for fog over our western counties. Anyway, it will be something to watch and perhaps adjust your travel plans for early Saturday morning. Other than that, only made a few changes to hourly temperatures to account for a slightly warmer trend this evening. Showers will start to move into northwest Middle TN shortly after sunrise Saturday morning. && .SHORT TERM... (This afternoon through Saturday Night) Issued at 159 PM CDT Fri Apr 28 2023 Scattered showers dot the radar this afternoon as the surface low slowly lifts northward out of the Ohio River Valley. ACARS soundings from BNA show ample moisture below 700 mb with steep low level lapse rates. Above 700 mb, the profiles quickly dry out. This is allowing these low top showers to develop but not really take off despite SBCAPE values between 500-1250 J/kg. CAPE values along with the shower activity will drop off this evening with the loss of diurnal influences. Overnight, Middle Tennessee will be stuck right along a warm front. Ample low level moisture will remain coupled with calm winds. Clouds will scatter this evening. This will allow areas of fog to develop. Model guidance indicates that some areas of fog could be become dense. Clouds will begin to move back into the area near dawn which could work against the fog, but we`ll have to keep an eye out for the possibility of a dense fog advisory overnight. Another system will approach the area on Saturday. The warm front will lift north of the area during the morning. Showers will approach the west during the morning and those showers will spread eastward through the afternoon. A cold front will be knocking on the door in the west by 00Z Sunday. That front will sweep through the area Saturday night ending the rain chances from west to east. There is a small chance of a storm Saturday afternoon and into the evening before instability falls off. Nothing strong or severe is expected. && .LONG TERM... (Sunday through next Friday) Issued at 159 PM CDT Fri Apr 28 2023 A drier pattern will settle in starting on Sunday with large scale troughing setting up centered over the Great Lakes. If you can look past breezy conditions, then Sunday looks pretty nice. There should be plenty of sunshine with temperatures spanning the 60s. Sunday night will be on the cool side with lows in the low to mid 40s. The 60s and 40s theme will continue on Monday and Tuesday as the large upper trough persists. There will finally be some movement on Wednesday as the trough slides east taking the coolest air with it. Middle Tennessee will stay dry through Wednesday. The next chance of showers will hold off until at least Thursday. && .AVIATION... (00Z TAFS) Issued at 632 PM CDT Fri Apr 28 2023 Tranquil weather at issuance, but things look to get foggy tonight. IFR to LIFR fog is possible at all Middle TN terminal tonight as skies clear and winds calm. Categories should start falling around 06-07Z and likely won`t improve until 14Z/Sat. Calm winds overnight should remain light and westerly tomorrow. && .PRELIMINARY POINT TEMPS/POPS... Nashville 53 77 53 67 / 0 40 40 20 Clarksville 50 73 49 64 / 10 50 10 20 Crossville 47 72 50 64 / 10 20 60 30 Columbia 51 76 51 67 / 10 40 40 10 Cookeville 49 73 52 64 / 10 30 40 30 Jamestown 48 72 50 64 / 0 20 50 40 Lawrenceburg 52 75 52 67 / 0 30 40 10 Murfreesboro 50 77 52 68 / 0 30 40 20 Waverly 50 72 48 64 / 20 50 20 10 && .OHX WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......Whitehead SHORT TERM...Reagan LONG TERM....Reagan AVIATION.....Unger
Area Forecast Discussion
National Weather Service Phoenix AZ
523 PM MST Fri Apr 28 2023 .UPDATE... Updated Aviation section. && .SYNOPSIS... Under strong high pressure, temperatures will continue above the seasonal normal through early next week. In fact, many lower elevation communities should breach the 100 degree threshold for the first time this year over the weekend. By the middle of next week, a low pressure system will become established off the California coast allowing temperatures to retreat closer to normal and yielding locally breezy conditions. Despite this transition, a continuation of dry weather should be expected. && .DISCUSSION... A trough is currently seen on WV satellite pushing through NM and ejecting into the Southern Plains this afternoon. Upstream from this is a high amplitude ridge that is slowly progressing eastward. The induced pressure gradient between the high and low pressures has been leading to the some breezy north to northeast winds, but mainly across high terrain areas of AZ. These breezes will continue through Saturday, while veering more easterly. Aircraft soundings out of Phoenix have shown a slight warming in the lower troposphere over the last 24 hours. This should yield highs this afternoon a degree or two warmer than yesterday. Some spots in Southeast CA and Southwest AZ may experience their first 100 degree day of the year. Others will have to wait until tomorrow or Sunday as temperatures continue to warm while ridging transitions across the area. Sunday still looks like the warmest day in the forecast, however NBM forecast highs for Saturday have trended a couple of degrees warmer than the previous forecast package, with 99F now forecast for Phoenix. NBM probability of reaching or exceeding 100F at Sky Harbor Airport (official Phoenix climate site) Saturday is up to 25%. Chances are higher on Sunday for Phoenix, ~70%, with a forecast high of 102F. A high of 102F on Sunday will tie a daily record if reached (see Climate section). The only thing that could potentially inhibit temperatures slightly will be clouds. High-res models suggest there will be an increase in high clouds through Sunday, but forecast sounds suggest they will not be very thick. Either way, widespread Moderate HeatRisk is expected with temperatures this weekend. So, take precautionary measures. .PREVIOUS FORECAST... Ridging will shift east into the plains during the first half of next week as a seasonally strong negative PV anomaly intensifies along the California coast. NAEFS mean output indicates central H7- H5 heights better than 3 normalized standard deviations below normal materializing, though the eastward extent of these anomalies remains in question and the primary cold core could essentially stall west of the Los Angeles basin given the blocking pattern. Nevertheless, an enhanced pressure gradient supported by the initial height falls and tightened thermal gradient should support increased winds Monday through much of the forecast area. NBM temperature guidance spreads widen substantially during the middle and latter half of next week in association with uncertainty on how the blocking pattern evolves and magnitude of additional height falls entering the SW Conus. Recent NBM output suggests temperatures briefly falling into a below normal category, though foreast confidence is low and ensemble output supports ~25% chance of only retreating back to around the seasonal normal. && .AVIATION...Updated at 0023Z. South-Central Arizona including KPHX, KIWA, KSDL, KDVT: A ridge of high pressure is building over the western CONUS as the southern end of a large trough moves onto the southern Plains. This will favor north and northeasterly flow aloft through Saturday afternoon. At the surface, north and northeasterly winds will overspread the TAF sites early in the TAF period. In fact, KPHX has already begun the transition. However, there may be some variability in directions before 02Z fluctuating between NEly and NWly. There will be variability in speeds early on as well with speeds sometimes below 6kts and sometimes brief gusts of up to 15-20kts. Overnight, directions will become more variable but speeds will mostly be less than 7kts. With daytime heating, southeasterly directions will overspread the Valley floor after 15Z/16Z with some minor gustiness possible. Light west winds develop in the afternoon. Otherwise, skies will be clear. Southeast California/Southwest Arizona including KIPL and KBLH: A ridge of high pressure is building over the western CONUS as the southern end of a large trough moves onto the southern Plains. Winds in the lower half of the troposphere will generally favor easterly directions through Saturday morning before trending to southerly in the afternoon. At the surface, KIPL will favor upvalley/downvalley patterns with east/southeast for much of the daytime and then westerly for much of the night. Anticipate KBLH will have a lot of directional variability after north/northeasterly this evening followed by southerly Saturday afternoon. Minor cirrus will increase Saturday afternoon but otherwise skies will be clear. && .FIRE WEATHER... Dry conditions with above normal temperature will persist through the weekend. Northeast wind gusts will be most pronounced early this afternoon in eastern districts though speeds should remain below critical thresholds. Enhanced easterly ridge top wind gusts may also be possible Saturday morning before relaxing the remainder of the weekend. Otherwise, minimum afternoon humidity levels will mostly fall below 10% with poor to fair overnight recovery of 15- 35%. Temperatures will steadily cool closer to the seasonal normal, and even below normal for a day or two, through next week with modest improvements in humidity levels as afternoon readings fall into a 10-20% range and overnight recovery improves towards a 35-55% range. However, winds may increase markedly during this transition, especially Monday where near critical thresholds may be reached. A locally elevated fire danger may continue into the middle of the week with gusty winds and low afternoon humidity values. && .HYDROLOGY...Updated 210 AM MST 4/26/2023 Gila: Flow in the Gila River continues to travel downstream through Yuma County as water releases from Painted Rock Dam continue. Releases from Painted Rock Dam remain above 3000 cfs. Continued releases from the dam will lead to inundation of downstream unbridged river crossings through Yuma County. Several unbridged roads in Yuma County have already reportedly been closed due to flooding. Flood warnings remain in effect downstream of Painted Rock Dam to the Colorado River. The latest USGS gauge observation along the Gila River near Dateland recorded a depth around 8.4 feet, which is just above action stage (8 feet). The latest forecast from the CBRFC indicates that flow in the river will remain above action stage through at least the next week. Thus, Flood Warnings along the Gila River will be in effect through at least May 2nd. && .CLIMATE... Record high temperatures: Date Phoenix Yuma El Centro ---- ------- ---- --------- Apr 28 104 in 1992 106 in 1992 106 in 2007 Apr 29 105 in 1992 106 in 1959 106 in 2013 Apr 30 102 in 1943 103 in 1943 104 in 2021 && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Benedict PREVIOUS DISCUSSION...18 AVIATION...AJ FIRE WEATHER...18 HYDROLOGY...Smith/Lojero CLIMATE...18