Stx_Thunder

WPC Excessive Rainfall risk upgraded for Day 3 outlook over lower TX coast today: https://www.wpc.ncep.noaa.gov/qpf/excessive_rainfall_outlook_ero.php * WPC currently going 3 - 5 in. (isolated 7 in. totals) in slight risk area if the now Invest 91L becomes a TC before landfall, in ERO discussion.

500mb High on the move, away... Today (19th): --- Gulf now full of atmospheric moisture:

In a Good nutshell. Usually is most of the time

Saw a few nice thunder heads and one with an overshooting top not too far offshore to the east later in the afternoon yesterday and a few very skinny (ultra-tropical) sea breeze cells off to the west inland. Obviously, none of those are associated with the incoming tropical entity, yet. But just nice to see more signs of a coming pattern change around TX coast. It doesn't actually look like there'll be flooding rains down here as the first major tropical entity of the year for the region is projected to keep moving at a steady pace. Even when it comes onshore, due to the stronger steering flow around the High not being too far away to the north. But just glad to see a significant change and especially relief coming this week from the very relentless summer heat this year. Which will thankfully give the A/C a major break with all the cloud cover and rain too. It thankfully also doesn't look like it'll completely dry out after it moves away later in the week as both the GFS and Euro are showing some more waves of deeper atmospheric moisture coming in at times from the Gulf and from another Low in the southwestern Gulf around the end of the week. So this should be the start of the usual September rains around TX coastal region. Albeit, could still end up being quite wet despite a very dry summer, with a (slowly) strengthening El Niño at this point. All grasses are brown down here too as it hasn't rained around the coastal bend since early July also. Which only amounted to about a quarter inch on average. I'd say a half inch or even a little more around Houston is not out of question, as the system (especially if it develops a closed circulation like a depression) could still end up tracking a bit further north as they tend to. Unless, the High ends up further south than currently projected. But with more organized convection from even just a mid-level Low can send a number of outflow boundaries further north. As that would help fire off more cells mixed with daytime heating up there, and with some of the deeper tropical moisture (can produce downpours even in low-topped cells or showers), being drawn further north from the eastern region of the circulation. And possible sea breeze assistance as well. From all convective scenarios I've seen around Houston over the years, it usually doesn't take much to get some cells going up there even if there is some subsidence aloft like from the dominant subtropical High this time of year, in this case. But yes, it's likely San Antonio gets more rain than Houston with this first major tropical entity of the year for TX coast given current projections of the 500mb high not too far off to the north.

WPC now also indicating a marginal excessive rainfall risk on the day 5 outlook for most of TX coast region on Tuesday. If it develops a 500mb circulation (regardless of any TC development), the risk would likely be upgraded as a Mid-level Low does create better support for lift and deeper (tropical) moisture advection aloft for more organized deep convection on the northern region. It should keep a steady track through the Gulf (mid-upper level high not too far off to the north providing stronger steering flow) that some shower/storms could start coming onto the southern TX coast by this Sunday.

Most Euro members on latest 0z run still holding onto good size generally southeast - northwest oriented swath of 2 - 5 in. average rainfall next week around middle TX coast and closer to a San Antonio - Del Rio line. If the system stays an open circulation aloft and especially given that this is a tropical entity, deeper atmospheric moisture from the southern Gulf and Carribean would get drawn further northwest in the onshore flow pattern around the northern side. Which would also be aided by the southwestern periphery flow around the 500mb high off to the northeast. WPC now spreading higher rainfall probabilities over San Antonio and Del Rio areas now as the 500mb high looks to stay more northeast, around the Arkansas/Tennessee region at least early next week. NBM precip output also spreading further inland to the northwest.

NBM and multi-global model outputs continue holding Strong with an S on TX Coast rainfall next week starting around 22nd (Tuesday). The real question now (regardless of any tropical development in Western Gulf if at all), is...: - How much rain? Euro op also coming back on track with rain over TX coast (instead of further east the past days). Though many of the members this week were already showing 2 - 4 in. swath on average, generally over middle TX coast region next week. Even more of them now on today's 12z run. NBM showing about 2 in. right along most of TX coast through 28th. - Latest 12z Multi-global model output today: *Some higher probabilities spreading over San Antonio later on 22nd now, also. Personally now, even just additional cloud cover would make a difference like the anvil shield from yesterday's thunder cluster around here did for me (and on A/Cs). --------- Also, good amount of deep dry air aloft over the state today seen on water vapor...:

Radar lighting up around South TX later this afternoon with that old front hanging down here: Was pretty dark off to the north on the southeast edge of the convective shield of that pretty strong easternmost cluster. Not surprising with all this crazy and quite persistent TX heat/humidity with very little dynamics aloft this time of year.

At this point, it's just beautiful to see WPC's forecast graphic early next week on the repositioning of that 500mb High that far away from TX, and the 588dm line so close.. The more likely scenario (and given the strong consistency of the NBM precip output over past 1 - 2 weeks), will be whatever comes in from the Gulf to all stay south of N TX through at least next week as both GFS and Euro ensembles are showing the mid-upper high Not moving far enough away from there (594dm line still in region). In fact, they're now starting to trend the High moving back southwest closer to TX panhandle later next week. Albeit, might be in a normally weaker state by then, nearing end of August.

Euro is wobbling around on its projection of a mid-level (700mb & 500mb) circulation the middle of next week, going further northwest between HOU - DFW on tonight's run with most of the rainfall now right around DFW area lol: NOAA's National blend of models output @ https://mag.ncep.noaa.gov/model-guidance-model-parameter.php?group=Model Guidance&model=NBM&area=CONUS&ps=area# - has been most consistent over the past week. * Still showing rainfall over entire TX coast around mid next week. Latest GFS tonight showing 997mb into Deep South TX around 23rd (about same time Euro forecasting its mid-level Low further northeast): https://pivotalweather.com/model.php?m=gfs&p=sfcwind_mslp&rh=2023081600&fh=168&r=conus&dpdt=&mc=

Euro already showing PWs well over 2 in. next week over Texas Coast region: With those values, (very?) heavy rainfall will no doubt, be a definite possibility. Heavy duty September rains a-coming on schedule, looks like..

Fairly impressive higher-end risk blob now (for 22nd) just off TX coast/south of HOU on very latest multi-model output from last night: Looking more like a potential, sudden El Niño-induced convective attack next week with that furnace High actually pushing away now from TX, nearing end of August..

Now that it's seemed like forever here on the coastal bend, saw an actual plethora and some sizable FW cumulus towers prior to seabreeze pushing inland close to noon Sunday (yesterday). Even more, convective signal just keeps getting better for TX Coast region next week (especially 22nd): * I had not seen both, in the longest time..... Actual relief and Thunder potential is in sight! September rains for the coast should be coming per usual.. Too bad for me being further south, T-storms do always love HOU area the most... Just as I remember seeing CPC's info and again now about the MJO (and for reference on here), Phases 1 and/or 8 show the most above normal precipitation anomalies over TX in most of the 3-month periods as well: https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/Composites/Precipitation/

Things are looking better each day now for the furnace dome High shrinking and actually losing grip on the TX Coast region very soon as even NOAA's, NBM output @ https://mag.ncep.noaa.gov, which is typically very conservative with its rainfall projection, is staying more consistent now for some kind of rainfall, daily on its 6-hr periods, the following week of the 21st. Most likely from deeper atmospheric moisture influxes (PWs 2 in. or greater which I'm seeing more persistently now on latest GFS runs coming ashore over TX coast), in a deeper E/SE flow aloft with those TUTT lows coming closer. The latest Euro run tonight is actually showing one TUTT moving northwest and coming really close to South TX just off to my south, basically tracking right along the Rio Grande on the 22nd. And the mid/upper-level High center moving significantly further north/east of TX than it's ever done anytime this summer. I haven't studied up too much yet on the MJO itself, but I am aware of the phases (1-8) and its impact on convective and precip patterns around TX. Though at least down here in the southern region, it doesn't seem to be a large driver of the often tropical (heavy-duty type) summer rains, until later September when the cold fronts get close. Unless.., most of the support aloft for convective development is Non-tropical like upper-level jet stream influence from the north/west. Also, now that El Niño has finally returned and as long as it doesn't strengthen too fast, I am looking forward to a fairly convectively active upcoming Fall pattern as shortwave troughs/impulses in the subtropical or southern stream jet do tend to track farther south in TX more often during EN phases (as opposed to LA ones), with a generally more northwesterly upper-level flow instead of southwesterly as that tends to cause more of the stronger impulses to eject farther north into the Plains and leaves more of TX, capped for deep convection and drier especially down here which just sucks. Hence, a 'lowering dew point front' only Which, even that on its own would actually be 100% welcome down here in STX at this point. Though because of the lower DP, it can actually allow overnight lows to end up lower without any cool air advection at all behind the front. Heat Index is not an issue at all when you have much lower dew points around 50 F (which is well below normal and very uncommon this time of year around TX coast). Even if actual air temp is 100 F, it can still feel "cooler" in a way because there's essentially no surface air moisture at all, at those DP values to produce a 'discomfort reaction' on the skin. Though I find those projected 40 DPs right around Houston like that of the this evening's GFS run to be a little too generous (unless the front does actually move off the upper TX coast there). That global model has its own little "excitement" ups and downs with each run. So I prefer the more stable Euro model/ensembles before being convinced, but does show DP dropping into the 50s around there for a short period.

The GFS model, since about 2 weeks ago, and now the European ensembles are showing a (lowering dew point) Front backdooring all the way down to Houston (or very near TX coast), around the eastern periphery of the slightly retreating/weakening northwest furnace High, early this coming week on Tuesday (15th). https://pivotalweather.com/model.php?p=sfctd_b-imp&rh=2023081206&fh=90 https://pivotalweather.com/model.php?m=epsens&p=sfcwind_mslp-mean&rh=2023081200&fh=90 With a more obvious and at least slightly cooling northerly mid/upper-level flow established and influenced from a nearby dipping jet stream just off to the northeast, and a few subtle shortwave impulses moving further south closer to the TX coast, this would likely spark at the very least, a few convective cells or shower/T-storms (possibly a bit strong in the afternoon), near it. The typical daily summer afternoon sea breeze front going inland from the Gulf coast could collide with the incoming front if it indeed does come closer to the I-10 corridor (Houston - San Antonio line), to focus *more convective development with better moisture pooling closer to the coast. As this scenario has happened before in past (including recent) Augusts with fronts nearing the TX coast before stalling/washing out. All of this would be an actual indication of the furnace mid/upper-level High actually starting to lose a bit more of its grip (at least for the southeastern half of TX), if that front *does* indeed creep further south all the way to the coast this upcoming week as the global models are projecting. ---------- On a longer range outlook side note, multi-global model compiled output on weather.us is starting to show "much better" Thunder potential on TX coast going into the following week of the 21st: https://weather.us/model-charts/multimodel/texas/tstorm-risk/20230821-1200z.html

This summer, at least here in South TX, is running quite similar to the 2009 summer, that I definitely remember. Which also involved a Strengthening El Niño phase (looking at CPC data), going into the fall with little clouds and rainfall until the end of August. When the 500MB high finally broke away for good down here. And no hurricanes to be found anywhere near the TX coast (which probably will be the case again this year). I see the end of August being the case for actual rainfall. As the models have been a rather disappointment lately, forecasting the break away of this TX loving furnace subtropical high. September rain and T-storms are normally a guarantee down here *every year. Regardless of the ENSO phase or any tropical storm or hurricane. So I'm not concerned about this atmospheric moisture-sapping high sticking around down here too much longer or through September. Given the ongoing, strengthening EN, I suspect with all this build up of (convectively very untapped) lower level heat content, the storms around the region could initially be quite strong when the high finally breaks away (usually off to the northwest). Which typically creates a cooling northerly/northwesterly mid/upper-level flow pattern southeast of the departing high, and potential early dipping of the jet stream into TX at the end of August or beginning of September. As was the case in 2009 and 2015. You get use to it once you've lived down here in South TX quite long enough or all your life. Despite the very persistent hot/dry summer pattern this year, June was actually the worst where a few nights, the Dew Point was staying right around 85 F during a stronger onshore flow pattern from the SE (usual direction). Which was unusual down here too as it's rare that it reaches that high any time of year. Though there has been a lot of breezy-windy days this summer. Even though I keep the indoor thermostat close to 80 most of the time, the windows were still condensating with that extremely moist Gulf surface flow. I had never seen that happen before in the summertime. Though, 70 F+ dew point for about 70% of the year on average is quite common down here around the Corpus and Brownsville area. It may have been more like 60%, 15 years ago.