Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
Issued by NWS Houston/Galveston, TX
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533 FXUS64 KHGX 091030 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 530 AM CDT Fri Aug 9 2024 ...New AVIATION... .SHORT TERM... (Today through Saturday Night) Issued at 257 AM CDT Fri Aug 9 2024 The Heat Miser`s grasp on Southeast Texas continues with yet another day of above normal temperatures. That`ll be in spite of a frontal boundary backing in from the northeast later this morning and lingering around the I-45 corridor throughout the day. This`ll be a key factor into our rain chances this afternoon, but heat is the most important impact so let`s discuss that first. With upper level high pressure remaining overhead along with 850mb temperatures in the 99th to MAX percentiles, surface temperatures this afternoon will be able to reach the upper 90s to low 100s. Moisture convergence along the frontal boundary will increase PW values up to 1.9-2.2", especially along and west of I-45. Above normal heat and elevated moisture isn`t exactly a good combination as it results in elevated heat indices. It`s not too surprising that a Heat Advisory is in effect for all of Southeast Texas through this evening with heat indices between 108-112F being possible. Now let`s discuss what all of this daytime heating means for rain chances in the afternoon. With PW values reaching the 75th to 90th percentile this afternoon along with a lingering frontal boundary/sea breeze, some fairly decent daytime heating should be able to allow some convection to break through the cap for isolated to widely scattered showers/storms to develop. This mainly looks to occur south of I-10 and west of I-45. While this is going on, another frontal boundary will be gradually drifting southward through North Texas. The 00Z CAMs are in fairly good agreement on a cluster of storms forming along then racing ahead of this frontal boundary as it tracks southward into the Brazos Valley in the late afternoon to early evening hours. While shear is essentially non-existent, moderate instability and steep low-level lapse rates will be enough to support some isolated strong wind gusts in the strongest storms. As a result, SPC has outlined a marginal risk of severe weather (level 1 out of 5) for portions of the Brazos Valley today. The frontal boundary will still be lingering around Southeast Texas on Saturday. Although the moisture will be lower and the capping will be a bit stronger, there still looks to be enough support between the lingering boundary and daytime heating to kick off some isolated convection mainly south of I-10 and west of I-45 in the afternoon. 850mb temperatures will be ever so slightly lower, which translates to surface temperatures being ever so slightly lower by about a degree or so compared to Friday. Heat indices will be more borderline for a Heat Advisory on Saturday, but areas west of I-45 would be the most likely to see another issuance if need be. Low temperatures on both nights will mainly be in the upper 70s to low 80s, so there won`t be much relief from the heat overnight. With heat indices around or above Heat Advisory criteria ( 108F), please continue to keep heat safety at the forefront of any plans that you make (especially if outdoors). Know the signs of heat related illnesses (heat stroke/heat exhaustion), drink plenty of water to stay hydrated, take frequent breaks from the heat, avoid strenuous outdoor activities during the hottest part of the day, wear sunscreen and loose/light-colored clothing, and ALWAYS ALWAYS ALWAYS LOOK before you LOCK your vehicle. Don`t forget about your pets as well! If the ground is too hot for the palm of your hand, then it is too hot for their paws. Batiste && .LONG TERM... (Sunday through Thursday) Issued at 257 AM CDT Fri Aug 9 2024 Mid/upper level ridging remains in place and helps to bring above normal temperatures to a majority of the area. A mainly light onshore flow persists as the area resides on the west side of a Gulf of Mexico surface high. High temperatures each day will be in the mid to upper 90s with a few locations possibly reaching 100 degrees. Heat index values do not peak until the Tuesday through Thursday time period when 108-112 readings are expected and a Heat Advisory will probably be needed. Even if there is no Advisory in effect, continue to take all heat precautions. Subtle weaknesses in the ridge could allow for some rain to edge back into the forecast starting on Monday, mainly in the morning near the coast and inland in the afternoon with the inland extent generally in/ around the Highway 59/69 corridor. 42 && .AVIATION... (12Z TAF Issuance) Issued at 530 AM CDT Fri Aug 9 2024 VFR conditions will prevail throughout the TAF period. Winds are light and variable this morning and will remain on the light side throughout the day, but will trend towards being northeasterly in the afternoon. Some isolated convection will be possible after 21Z, but coverage looks to be too sporadic to include it in the TAFs. The only TAF with convective mentions is CLL where a cluster of storms may develop this afternoon/evening. It`s worth mentioning though that the two 06Z hi-res models have walked back on this solution. With most of the 00Z model suite indicating convective potential though, decided to keep in VCSH for now. Batiste && .MARINE... Issued at 257 AM CDT Fri Aug 9 2024 Light winds and low seas will prevail. During the overnight hours, winds may intermittently increase to around 10 to 15 knots. Rain chances remain low. 42 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 99 78 99 77 / 20 20 10 0 Houston (IAH) 100 80 99 79 / 10 20 10 0 Galveston (GLS) 93 83 93 82 / 10 10 10 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Heat Advisory until 9 PM CDT this evening for TXZ163-164-176>179- 195>200-210>214-226-227-235>238-300-313-335>338-436>439. GM...None. && $$ SHORT TERM...Batiste LONG TERM....42 AVIATION...Batiste MARINE...42