Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
Issued by NWS Houston/Galveston, TX
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936 FXUS64 KHGX 220724 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 224 AM CDT Sat Jun 22 2024 ...New SHORT TERM, LONG TERM, MARINE... .SHORT TERM... (Today through Sunday Night) Issued at 210 AM CDT Sat Jun 22 2024 Ridging in the mid to upper levels of the atmosphere should bring warmer conditions over the weekend and into the beginning of next week. Even with abundant moisture still available, subsidence from this ridge will limit rain chances. If any showers/storms do develop, it`ll probably be on Sunday, with isolated development in areas south of I-10 with support from the sea breeze. Minor coastal flooding remains a concern today for coastal areas from High Island to San Luis Beach. Water levels ares still expected to reach 3.5 ft above MLLW later this morning with high tide. Coastal flood advisories remain in effect for these coastal areas until 10 PM tonight. Coastal communities should continue to exercise caution while traversing these areas to allow waters to recede from any impacted roadways. Rising 850mb temperatures and decreasing cloud cover during the afternoon suggest warmer conditions over the next few days (especially with lacking rainfall). Highs will be in the upper 80s to upper 90s over the weekend, with lows in the 70s to lower 80s near the coast. Previous days have indicated afternoon mixing for dewpoints has been rather poor, resulting in elevated heat indices. By Sunday, heat indices are expected to reach 104-110 during the afternoon hours, which may warrant a Heat Advisory during the day. The heat risk for Sunday will be moderate (3/5) for most people participating in low-impact, leisurely outdoor activities. However, those participating in strenuous outdoor activities may feel major (4/5) heat stress. Remember to drink plenty of fluids, wear lightweight clothing and avoid strenuous outdoor activities during the hottest part of the day. 03 && .LONG TERM... (Monday through Friday) Issued at 210 AM CDT Sat Jun 22 2024 One could very likely get away with hand-waving over the long term portion of the forecast with "It`s summer". And, while tempting, we`ll get into discussing things a little more in depth than just that. But also, as long as you`re considering that heat safety practices are now just typical summer behavior around here (Narrator: they are) - it wouldn`t be totally wrong to leave it there. Alright, so...next week. The big story is really going to be nuances in subtropical ridging - where it`s strongest, and just how strong it looks to be. And of course, at range, the place we really want to be looking for that is in the ensembles. Using mean 500 mb heights, both the NAEFS and Euro ensemble show a strong ridge on tap for next week. NAEFS is a little bit weaker, showing pretty persistent 90th percentile heights for much of the week. The EPS is a bit stronger, and perhaps with the domiest part of the heat dome centered a little farther east over Texas. As a result, some mid-level heights over the 97.5th percentile start to creep into the area. These well-above average heights finally fade out late in the week as a shortwave trough dives in...mostly to our east, but close enough to knock down those 500 mb heights below the 90th percentile. Taking it down a bit lower in the column, and we see a somewhat similar, but more modest pattern in 850 mb temps. 90th percentile 850 temps emerge over our area in the both the NAEFS and EPS Wednesday and Thursday, but otherwise below the 90th percentile. Finally, at its most modest, there is virtually no signal for extreme high temps in the area in the Euro ensemble`s Extreme Forecast Index. So, ultimately, when the NBM gives me a string of highs in the mid-90s, which is definitely above average albeit not eye-poppingly so...I`m largely cool with taking what it gives me. The primary exception is on the immediate coast - due to what I suspect are land/water interface issues, Galveston and similar spots are just too cool, so I nudged the "island" zones up a bit to account for that. Of course, around here, the raw temperatures are not the only consideration to make here when it comes to heat threats. Sometimes humidity can be just as, or even more important. So where do things stand here? Well, it`s looking kinda rough, especially deeper into the week. NBM lows are pretty unanimously in the mid to upper 70s, except on the coast, where temps have trouble getting below 80. This is a pretty solid indication that we are dealing with a high moisture airmass dominating SE TX through the week. During the daytime, peak heat index values drift up and up and up through the week, from a point where we might need to consider heat advisories, to where if the NBM were to verify, we`ll eventually need widespread heat advisories, and maybe even consider excessive heat warnings. Now, I am a bit concerned here that this may be a bit on the aggressive side. NBM is infamously too high with afternoon dewpoints, and that implies that these heat index numbers might be a bit inflated because of that. However, it doesn`t seem to struggle as much with overnight dewpoints, and we can see the upward trend in low temps, so...maybe there`s a little something there? For now...stay tuned. Our daily dance of temp, humidity, sun, and wind is going to go through a daily evolution, and we should be able to flesh out expectations in the days to come. Another confounding factor comes down to something I haven`t even brought up yet, and that`s the potential to have things disrupted by rain/storms. Each day this week, we can expect to see the typical diurnal pattern for cloud and shower development, with any activity focused more over the Gulf in the late night/early morning hours, and gradually shifting towards coastal areas and a bit inland with the seabreeze in the afternoon. In the first half of the week, I`d expect the amplitude of this pattern to be more muted, with even peak afternoon activity being isolated to widely scattered at the most. Late in the week, when that shortwave trough I mentioned briefly up top is rolling through, that may create a modestly more conducive environment for afternoon showers and storms, with more scattered coverage near the seabreeze. Regardless of how it plays out precisely, the character of this activity will be very spotty. Rainfall amounts may vary wildly, with most seeing little to no rain, but those to win the day`s rainfall lottery could see a brief little downpour before that shower moves off and/or dissipates. Luchs && .AVIATION... (06Z TAF Issuance) Issued at 1232 AM CDT Sat Jun 22 2024 VFR, virtually SKC overnight. CXO has shown potential for some light fog, so went with 6SM BR overnight there to indicate variable amounts of VFR fog, as it is a known foggy spot. However, not anticipating it making it down to MVFR...though it is CXO, so there`s always a chance. Similarly, have a smattering of FEW/SCT at MVFR heights for potential small amounts of lower cloud, but no expectation of enough cover to force a CIG. ESE-SE winds pick up to around 10 knots for the afternoon, then we calm back down again after sunset. Luchs && .MARINE... Issued at 210 AM CDT Sat Jun 22 2024 Small craft should continue to exercise caution tonight and Saturday, in particular over the offshore waters as seas continue to subside. Light to occasionally moderate onshore flow will develop Sunday and continue through the next few days. Long period swells associated with the next potential tropical disturbance are possible later in the weekend into early next week. There will be a daily risk of isolated showers and thunderstorms every day through next week. At the coast, some lingering minor coastal flooding may occur at and near today`s high tide cycle. This is a particularly concern around Galveston Bay, and most specifically on the Bolivar Peninsula, where water levels at high tide are expected to again reach around 3.5 feet above MLLW. Additionally, emergency managers report that a good deal of erosion has taken place on area beaches, increasing the vulnerability to coastal flooding. So, while the Bolivar is of particular concern, the coastal flood advisory around the entirety of Galveston Bay will remain in place today. Also, there is still some elevated potential for dangerously strong rip currents on all Gulf-facing beaches, so that will be another consideration for those headed on a Saturday trip to the water. Luchs && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 94 72 96 76 / 0 0 0 0 Houston (IAH) 94 75 95 77 / 0 0 20 0 Galveston (GLS) 88 81 89 82 / 0 0 20 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Coastal Flood Advisory until 10 PM CDT this evening for TXZ214- 313-338-438-439. High Rip Current Risk through this evening for TXZ436>439. GM...Small Craft Should Exercise Caution through this evening for GMZ370-375. && $$ SHORT TERM...03 LONG TERM....Luchs AVIATION...Luchs MARINE...Luchs