Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/22/17


Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
917 PM CDT Sat Oct 21 2017 .UPDATE... The much talked about cold front is currently headed south and located across a Wichita Falls to Odessa, Texas line. Along it, strong to severe thunderstorms are ongoing across north Texas and Oklahoma. However, as the front continues to shift south, the stronger lift and forcing dynamics will remain north in association to the vorticity maximum over Oklahoma. Wile SPC mesoanalysis and suggested GFS/NAM BUFR soundings indicate upwards of 2000 J/KG of MLCAPE over the region, a strong cap is also in place per these same sources. Furthermore, aircraft data out of Austin and San Antonio also indicate the presence of the capping inversion. This will keep any pre-frontal activity at bay through the evening. The showers over San Saba to Comanche Counties north of the area are elevated in nature due to the overspreading of weak upper-level divergence. RAP mass fields indicate surface convergence will weaken as the front passes through the region while the best mid- and upper-level support lag behind. A strong thunderstorm or two may still be possible with the passage of the front overnight but overall trends appear to suggest only pockets of brief heavy rain and general thunderstorms along a Fredericksburg to Giddings line and north. Have reduced rain chances farther west and south through the overnight. The front should be through the entire area by late morning to near noon Sunday with gusty north winds but clearing skies. && .PREV DISCUSSION... /ISSUED 717 PM CDT Sat Oct 21 2017/ AVIATION... /00Z TAFS/ Vfr skies remain expected through the evening with some areas of 1000-2000 ft cigs expected after midnight. Lowest cigs should be limited to the higher terrain areas. A brief dip into ifr could be possible right as the cold front arrives and areas of convection congregate along the front. Frontal timing appears to be consistent among the past several runs of rapid refresh models. Regarding the potential for TSRA, would suspect that we`ll no longer need to consider the TSRA prevailing at SAT/SSF by the 06Z update given the mesoscale trends in the HRRR. However, have found that the convective handling of the HRRR runs around the 00z init time often deviate from the broader consensus of qpf for some reason. Thus will stick with the earlier foreast trends and modify late this evening should the 00Z runs reflect the decreasing TSRA potential. Post-frontal sky conditions should improve rapidly Sunday morning given the deep layer of northerly winds behind the font. PREV DISCUSSION... /ISSUED 252 PM CDT Sat Oct 21 2017/ SHORT TERM (Tonight through Sunday Night)... For the rest of the afternoon, a weak embedded disturbance within the larger shortwave has disturbed CU fields enough to produce some showers along and just east of the I-35 corridor near Austin and Georgetown. Proximity soundings from just about all models show the cap holding on to prevent much in the way of anything more than a very isolated thunder chance but included slight chc PoPs for this area and east for the rest of the afternoon. The bigger forecast focus is the approaching cold front overnight tonight that will trek across Texas and reach the northern CWA likely just before dawn. The TTU-WRF has been consistent with timing of the front while the HRRRX continues to speed up and generate more convection with each run. Looking at the current speed of the front, do think the faster HRRRX is valid thus have slightly sped up the fronts arrival in the grids but only about an hour or so. As far shower and thunderstorm potential, the main threat will be gusty winds and not much else for hazards. Just about every CAM produces healthy outflow with convection firing in northern Texas, and with the faster trends in the front as seen in the HRRRX previously noted, this would further add confidence in gusty winds and limit any hail potential. Still seems to be some disagreement in the western extent of the convective line. SPCs SSEO guidance shows enough outcomes extending into the Plateau and Hill Country to warrant at least chance PoPs during fropa Sunday morning. Thus have reflected as such in the grids. The front should be clear of the CWA by 18Z, resulting in a breezy, mild day Sunday afternoon. Did bump up gust potential to a max of 30 mph late morning and mid day as a fairly strong pressure gradient looks to be in place post fropa. These should die down by the evening and allow for a very favorable radiational cooling set up with high pressure, light winds, and clear skies. Thus, lowered min T for Monday morning to the lower end of the ECM and MEN ensemble guidance. LONG TERM (Monday through Saturday)... A rather benign weather pattern for much of the week as Sunday`s front dries out the area and gradual warming occurs through mid week. Another cold front is progged to push through the area Friday which may be a more significant temperature changer for South Central Texas. At current, extended guidance shows highs next weekend struggling to exceed 70 degrees at least for the northern CWA. Still some model disagreement in timing and strength this far out so left this to the SuperBlend for now. However, no hazards are expected through the extended. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 65 77 50 83 55 / 80 20 0 0 0 Austin Bergstrom Intl Airport 65 79 47 83 53 / 80 20 0 0 0 New Braunfels Muni Airport 66 81 47 82 53 / 50 30 0 0 0 Burnet Muni Airport 60 77 45 81 52 / 90 10 0 0 0 Del Rio Intl Airport 64 81 51 83 56 / 10 - 0 0 0 Georgetown Muni Airport 63 76 46 82 53 / 90 20 0 0 0 Hondo Muni Airport 67 85 46 83 52 / 20 10 0 0 0 San Marcos Muni Airport 66 81 47 83 53 / 60 30 0 0 0 La Grange - Fayette Regional 68 79 47 81 55 / 70 60 0 0 0 San Antonio Intl Airport 67 82 49 82 55 / 30 20 0 0 0 Stinson Muni Airport 68 85 50 83 55 / 30 20 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Mesoscale/Aviation...Oaks Synoptic/Grids...Allen
Area Forecast Discussion
National Weather Service Houston/Galveston TX
927 PM CDT Sat Oct 21 2017 .DISCUSSION... Cold front is through the Panhandle this evening and is timed to reach our far northwestern forecast area around sunrise tomorrow. Lines of showers with embedded thunderstorms will likely begin feeding into the downstream/pre-frontal trough as the main boundary reaches the I-35 corridor shortly after midnight. Under a capped downstream environment expecting late night lowering cloud heights ...a passing light shower and weakening winds as the front moves into and across central Texas. Expecting the bulk of the TSRA to reach the northern CWA during the overnight Sunday morning hours ...Houston metro a couple of hours after sunrise and across the coastal counties during the mid to late morning hours. The main front is forecast to pass off the coast early Sunday afternoon with morning precipitation quickly coming to an end...gusty northwesterlies and clearing skies the main theme Sunday afternoon. In the maritime...Sunday night/Monday morning Advisory level northerlies to blow across coast/upper Texas Gulf waters. Backing high pressure to move into eastern Texas through tomorrow night/Monday morning. 31 && .PREV DISCUSSION... /ISSUED 625 PM CDT Sat Oct 21 2017/ AVIATION... Most terminals should see fairly benign conditions this evening. MVFR cigs should eventually fill in around/after midnight. Attention turns to north Texas where a line of showers and thunderstorms associated with a southward moving cold front approaches northern parts of se Tx around 10z and off the coast by 18z. Best estimated timing will be reflected in the TAFs. Primary threat with the storms will be gusty winds and brief heavy downpours. Ceilings will lift and gradually clear out during the late morning and afternoon hours leaving mclear conditions and gusty nnw winds during the daylight hours (also at night near the coast). 47 && PREV DISCUSSION... /ISSUED 319 PM CDT Sat Oct 21 2017/ Warm and gusty this afternoon with a few showers and isolated thunderstorms from around PSX-ARM-66R-DWH-6R3. These should continue to expand slowly inland but will be fighting some capping around 700-750mb per AMDAR soundings. Closer to the LLJ axis scattered showers ongoing northwest of Caldwell and College Station. Cold front has moved through Amarillo and as it pushes southward expect storms to become more numerous across NTX tonight. Front pushes into the CWA near College Station around 4-7 am Sunday and Houston around 6-10 am and Galveston 9 am-1 pm. Timing differences still abound in the models hence the 3-4 hour time windows for the FROPA. The environment supports a swath of storms along and ahead of the from with an erosion of the cap and little to only modest shear. Expecting a multicellular nature to the storms with rainfall of 0.25 to 2 inches for the most part. As the storms get down closer to the coast and into the nearshore waters the wind gust potential gets higher and could see some gusts of 25-40 mph with the storms. Quick drying by mid afternoon across the area and temperatures only reaching the upper 70s to lower 80s inland and lower to mid 80s (depending on frontal timing-if it is slower then temperatures across the southern 2 tiers of counties will need a boost of 2-4 degrees) along the coast. Dry weather follows with persistent Sunday night through Monday afternoon. Cool morning Monday in the upper 40s to mid 50s. High pressure builds and should drift over the area early Tuesday morning relaxing winds and allowing temperatures to again fall to a respectably cool lower to mid 50s (these are near the superblend/regblend but with excellent radiational conditions present will probably need to go a little lower). Next upper trough drops down in NW flow aloft and quickly swings a reinforcing cold front through the area Tuesday late morning/early afternoon with gusty northerlies. Noticeably drier air with this one so no precip expected and with a few days of dry northerly flow will begin to edge up the fire danger into elevated conditions for the available dry fuels. Pleasant weather otherwise Tuesday through Thursday with a deepening upper trough taking shape Friday-Saturday over the Northern Plains into the Great Lakes which should push another cold front through the SETX region Friday afternoon-Saturday morning bringing a chance of showers and thunderstorms back into the forecast. 45 && MARINE... After a day of light to moderate winds over the waters, look for moderate to strong onshore winds to return this evening. The winds will be marginal for SCEC conditions, but holding off for now as the ambient gradient looks to slacken a bit, which would limit the nocturnal bump up in winds. Of course, tides will continue to be an issue with the long onshore fetch, but do not expect high tide tonight to be quite as problematic as last night - high tides will not be an issue once the front goes through. Thunderstorms can be expected with the front, bringing locally high winds and waves. Once the front is through, offshore winds may push some water out of shallow areas. At this time, it appears these winds may not be strong enough or at quite the right angle to necessitate a low water advisory. This will have to be watched, however, as stronger winds and/or a more favorable wind direction could cause issues. Speaking of those offshore winds, they look to reach to at least near small craft advisory thresholds, and an advisory may be needed for tomorrow night before diminishing on Monday. This lull may only be brief, with the potential for caution or advisory-level winds returning Tuesday into the mid-week, and then again late in the week ahead of another cold front. Luchs && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 70 79 49 80 55 / 70 70 10 0 0 Houston (IAH) 74 82 55 78 57 / 40 90 10 0 0 Galveston (GLS) 77 82 63 76 65 / 20 70 10 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ Discussion...31/47