Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
Issued by NWS Houston/Galveston, TX
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299 FXUS64 KHGX 242340 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 640 PM CDT Fri May 24 2024 ...New AVIATION... .SYNOPSIS... Issued at 257 PM CDT Fri May 24 2024 Hey, it`s summer now...Longhorn out front shoulda told ya. To commemorate the traditional beginning of summer, the atmosphere is gifting us with conditions that would be right at home or even on the warm side in July or August, much less Memorial Day. We`ll also be doing our near-daily check to see if any late afternoon/evening storms make their way into the area. Tonight looks to have some promise as storms now initiating over North Texas may grow strong enough to survive into northern portions of the area. But I`m also eyeing next week, as a northwest flow pattern aloft gets set up. Speaking of the heat, even though the numbers aren`t too eye- popping on an absolute scale, they are are definitely on the warm side for this early in the summer. Early season heat can be sneaky in that impacts to unacclimated bodies can start being problematic at lower levels, so working to keep yourself cool early in the summer, with heat typical of deeper in the season, and during a holiday weekend with lots of outdoor activities is a wise plan. && .SHORT TERM... (This evening through Saturday Night) Issued at 257 PM CDT Fri May 24 2024 Today begins the holiday weekend for most (some of us get to be here working all weekend!), and we`re already getting an initial taste of hotter conditions. Most obs around the area are reporting heat index values in the 102-105 range thanks to temps in the lower 90s and dewpoints in the upper 70s. Isolated spots - hey there, Katy at 108 - are even higher on the scale. Going into tonight, those high dewpoints are going to be key for the overnight forecast. The closer you get to the coast and the source of this deep, Gulf moisture, the harder we have been finding it to drop below 80 degrees, and that is not going to change for at least the next couple of nights. For those in the northern part of our area - Bryan/College Station, Madisonville, Crockett...basically those living north of the big Sam Houston statue, you`ve also got to keep an eye on those storms getting going in North Texas this afternoon. These storms will be gradually heading your way. The environment over most of Southeast Texas isn`t very supportive of storms, but for those folks up north, there could be just enough for some isolated strong/severe, but weakening, storms to cause a bit of trouble tonight before dying out. Tomorrow slides us up a bit more as far as the heat goes. It won`t be "too hot", in the sense that 850 mb temperatures are "only" exceeding the 97.5th percentile in both the NAEFS and Euro ensemble means. Yeah...I`m looking at my high temp map and dewpoints, and this just looks like the dog days of summer to me, not late May. One...nice...thing about Saturday is that the depth of moisture may not be as great, allowing for some modestly drier air to mix down in the afternoon. This won`t do a whole lot, with dewpoints only forecast to get into the lower 70s but it`s better than nothing. Combine that humidity with temperatures inching up more towards the middle 90s, and inland heat index values look to peak out in the 105-107 degree range, with triple digit peaks all the way to the Gulf. && .LONG TERM... (Sunday through next Thursday) Issued at 257 PM CDT Fri May 24 2024 The unseasonable heat persists all the way through the holiday weekend. Ensemble mean 850 temps remain above the 97.5th percentile, and look more like exceeding the 99th percentile, and may even threaten the high end of the model climatology. The Euro ensemble`s Extreme Forecast Index shows Sunday similar to Saturday, in that a portion of the area is showing a signal for extreme heat...exceeding 0.5. On Monday, it turns that dial up some more, with most all of the area above 0.6, and in some locations going as high as the 0.8 to 0.9 range, indicating high confidence in that high-end heat. Let`s not discuss the EFI for overnight lows, which indicates an even stronger signal for high- end values. If you`ve been outside late at night or just before dawn in recent evenings...you already know, and it`s not going to get any better. There are a few different ways we can try to put this weekend`s heat into context. One is the traditional heat index, which considers temperature and humidity, and assumes a shaded location and ignores wind. This is probably pretty useful if you plan on being outside, but generally shaded from the sun and wind, and don`t plan on being particularly active. The 105-107 peak values on Saturday look similar on Sunday, but nudging upward slightly into a 106-109 range. This is high enough that if the forecast holds, we would need to consider heat advisories. As the previous paragraph hints at, Monday ups the ante even more, as my peak heat index forecast values push up to around 110 degrees. This is partly from high temperatures, but also appears to be aggravated by deepening moisture, keeping afternoon dewpoints from mixing down as much as I mentioned above for Saturday. There are a couple other ways to look at heat impacts as well. One is an experimental product known as HeatRisk, making its way over from NWS offices in the West. This is particularly useful in putting the forecast temperatures in a historical context, as it puts the forecast into risk categories based on high and low temperatures compared to climatology. For Saturday, Sunday, and Monday, the bulk of the area falls into the Red/Major (level 3 of 4) category. This highlights that while the numbers we`re discussing "sound" normal compared to the entirety of summer around here, it`s actually quite hot relative to what we typically see around Memorial Day. Finally, there is the Wet Bulb Globe Temperature that we can also look at. If you are a veteran, distance runner, and/or competitive marching band person, there`s a good chance you`re already familiar with this index! For those unfamiliar, it is a complex index that takes into account temperature, humidity, wind, and the intensity of the sun`s rays. This makes it useful for those who are particularly active outdoors and more exposed to the elements. This index is also binned into threat categories, and most of the area peaks in the moderate (3 of 5) category tomorrow, jumps up to the high (4 of 5) category Sunday, and further increases into the extreme (5 of 5) category on Monday. So really...any way you slice it, it`s going to be hot and unseasonably so. Especially given the holiday weekend and our relative lack of acclimation to summer conditions, it could potentially be dangerous if you don`t take steps to keep yourself cool and minimize exposure to the conditions...especially if your holiday plans are active ones! Fortunately, being aware of the expected heat and taking proactive steps to mitigate their impacts will do much to prevent heat illness/injury. Beyond Monday afternoon, we do look to see some improvement as far as the heat goes. A low pressure center passing through the Great Lakes looks to nudge a weak, backdoor front through the area Monday night. This won`t do a whole lot to bring relief to the area, but it will help modestly. Look for temperatures to step down slightly into the lower 90s on Tuesday, around/just above 90 on Wednesday, and even back to seasonably average around/just below 90 degree highs on Thursday. Of course, this weak front will also mean potential for some showers/storms Monday night...and then we`ll be playing the "Look to North Texas" game deep into next week, as a northwest flow pattern aloft emerges. && .AVIATION... (00Z TAF Issuance) Issued at 640 PM CDT Fri May 24 2024 TAFs will become MVFR this evening/overnight with south winds around 5 to 10 knots. TSRA chances are best at CLL this evening, and we will monitor as activity off to our W and NW evolves. Becoming VFR around 15Z-18Z along with increasing/gusty S to SE winds. VFR into tomorrow evening followed by developing MVFR ceilings heading into Saturday night. 42 && .MARINE... Issued at 257 PM CDT Fri May 24 2024 Moderate southeast and south winds will prevail through the Memorial Day weekend, occasionally becoming stronger and gusty. Seas will remain somewhat elevated...generally ranging between 4 and 6 feet. Recreational boaters are urged to exercise caution this Memorial Day weekend and check the current conditions and forecast before venturing out. At area beaches, this moderate to strong onshore flow will also result in tide levels elevated above the typical astronomical tides, and also make dangerous rip currents likely. Given the fair, hot weather for the holiday weekend, beaches will likely be busy, and beachgoers will need to be alert to water conditions. && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 75 95 77 94 / 30 0 0 10 Houston (IAH) 78 94 78 94 / 10 0 0 0 Galveston (GLS) 80 89 82 86 / 10 10 10 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Beach Hazards Statement until 11 PM CDT this evening for TXZ436>439. GM...Small Craft Should Exercise Caution until 11 PM CDT this evening for GMZ330-335-350-355-370-375. && $$