Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
Issued by NWS Houston/Galveston, TX
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977 FXUS64 KHGX 271734 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 1234 PM CDT Mon May 27 2024 ...New AVIATION... .SHORT TERM... (Today through Tuesday Night) Issued at 251 AM CDT Mon May 27 2024 Key Messages: Excessive Heat Warning in effect until 10 PM tonight for portions of SE Texas Heat Advisory in effect until 10 PM tonight for locations outside of the Excessive Heat Warning Marginal Risk for severe weather tonight and Tuesday for much of SE Texas The hottest day in our streak of hot weather days has arrived, and following today`s heat indices of 105-115 degrees we will begin to see a slight (and very gradual) decrease in HI values through the rest of the week. For today though...With this being an extraordinarily hot day, and a holiday, please remember to take precautions in the heat! If you plan to beat the heat by taking a dip in the Gulf, continue to practice beach safety. We have received a few reports of people becoming caught in rip currents this holiday weekend, and today will feature another high risk for rip currents. If you find yourself caught in a rip, remember to wave, yell, and swim parallel to the shore. Avoid swimming near piers and jetties where rip currents are more likely to develop. In addition to the heat and beach safety, there is a risk for severe weather later today (looking like the evening to just before midnight time frame) and again on Tuesday. SPC has outlined most of the area in a Marginal Risk (level 1 of 5) for both Monday and Tuesday. The severe weather threat is conditional on whether or not the robust cap in place over the area erodes ahead of the storms. Hi-Res guidance has varied run-to-run on location and strength of storms, with the latest HRRR showing the storms dying off as they approach the Brazos Valley. Digging a little deeper into the setup, 500mb level shows a quasi- zonal flow with a few disturbances and pockets of PVA traversing SE Texas this evening into tonight. Further west a boundary is expected to setup over Central Texas which will trigger storms out towards the San Antonio area. These storms will track southeast and if the cap holds together, they should weaken upon arrival; however, if the cap is able to erode (could happen with daytime heating, cooling off in the mid-upper levels, outflow boundary interactions), storms would have plenty of CAPE to work with. They would also have the potential to become organized with decent shear. This would lead to the potential for damaging winds, large hail, and a brief isolated tornado. Overnight Monday into Tuesday morning will feature more tranquil weather. Lows will be in the 70s to around 80s with pretty humid conditions. NW flow will take over Tuesday and will help trigger the next threat of severe weather from that direction during the evening hours. As mentioned in the previous discussion, this setup has the tendency to be more conditional with the threat for severe thunderstorms. Highest PoPs lie in the NW counties. Strength and longevity of storms will largely depend on the erosion of the capping inversion and timing of arrival for PVA. Damaging winds and hail will be the main hazards with any storms that are able to make it into SE Texas. In any case, have multiple ways to receive alerts today and Tuesday. && .LONG TERM... (Wednesday through Sunday) Issued at 251 AM CDT Mon May 27 2024 Less hot, but somewhat unsettled pattern takes shape as upper ridging retreats a bit further southeast. This will allow disturbances embedded in the wnw-nw flow aloft to track a bit further south into the region. Low-mid level capping will also be less dominate from keeping shra/tstms from developing or maintaining themselves as they move in. A continued onshore flow will prevail and sufficient moisture will be available for scattered precip across portions of the CWA each day. The main forecast challenge is determining the more favorable time periods for convection. Guidance has been indicating the potential for upstream development, maybe an MCS or two, during the last half of the week...but at varying time periods and locations. This is typical for such a pattern and makes the POP fcst difficult - especially when the mesoscale comes into play. Suspect NBM is substantially too low with POPs for a good part of the extended fcst, but I really cannot say exactly when. For the grids, I did about a 50% mix NBM and a 50% mix of various deterministic models and WPC guidance. At this time, wouldn`t be overly surprised if early Wed morning, Wed night-Thursday morning, and Friday daytime/evening might be the more favorable times...with northern parts seeing better chances than the coast. But again, forecast confidence in regards to the specifics is fairly low. 47 && .AVIATION... (18Z TAF Issuance) Issued at 1212 PM CDT Mon May 27 2024 MVFR ceilings are starting to lift, but visibility issues could per- sist through the afternoon given the haze/smoke moving in from the S (Gulf). Expect conditions to improve to VFR through the afternoon as onshore winds slowly increase (4-9kts). Isolated storms remain poss- ible late this afternoon/evening for our western areas, but there is still quite a bit of uncertainty regarding timing. Otherwise, we are going to see a return of MVFR CIG overnight with patchy fog possible again into Tues morning. 41 && .MARINE... Issued at 251 AM CDT Mon May 27 2024 Winds and seas decrease somewhat today into the early and midweek time period. That said, recreational mariners are urged to use extra caution today considering the increased holiday traffic. Will maintain the Beach Hazards Statement through this evening along area beaches due to excessive crowds and the number of rescues reported by Galveston Beach Patrol the past 2 days. During the second half of the week, moderate to occasionally strong southeast winds and 4 to 6 foot seas resume with a long fetch setting up across the Gulf. Showers and thunderstorm chances return to the forecast late Tuesday night and Wednesday. Though chances are better inland, we anticipate some disturbances passing through this week that are difficult to time days in advance. 47 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 96 76 92 74 / 10 20 20 40 Houston (IAH) 97 78 93 77 / 0 20 10 30 Galveston (GLS) 89 79 87 80 / 0 0 10 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Heat Advisory until 10 PM CDT this evening for TXZ163-164- 176>179-195-196-198-200-214-235>238-300-313-335>338-436>439. Excessive Heat Warning until 10 PM CDT this evening for TXZ197- 199-210>213-226-227. Beach Hazards Statement until 10 PM CDT this evening for TXZ436>439. GM...None. && $$ SHORT TERM...Adams LONG TERM....47 AVIATION...41 MARINE...47