Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
Issued by NWS Houston/Galveston, TX
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474 FXUS64 KHGX 211917 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 217 PM CDT Sat Sep 21 2024 ...New SHORT TERM, LONG TERM, MARINE, TROPICAL... .SHORT TERM... (This evening through Sunday Night) Issued at 217 PM CDT Sat Sep 21 2024 Upper level ridging remains in place overhead, resulting in another hot and humid day. A few light showers will continue to develop near the coast this afternoon, before tapering off by early this evening. A quiet night is expected with patchy low-lying fog possible. Conditions in Southeast TX will continue to be dominated by the ridge aloft and at the surface on Sunday. Expect another hot and humid day with highs in the 90s. Heights will gradually weaken as mid/upper level ridge axis moves to our east and a cold front slides southeast across the Plains. By Sunday evening/night....strong newly persistent onshore flow should begin to push deeper Gulf moisture into the region. Increasing moisture combined with a broad surge of theta-e advection will lead to increasing rain/storm chances from the coast overnight. JM && .LONG TERM... (Monday through next Friday) Issued at 217 PM CDT Sat Sep 21 2024 By Monday, the main ridge axis will have shifted eastward as an upper level trough begins to dip down into the Central Plains. Going into midweek is when things get a bit interesting as the 12Z deterministic models have come into agreement on this evolving into a cutoff upper level low over the Southern Plains. The GFS is finally somewhat onboard with this solution...it keeps the upper low closer to the Mississippi River Valley whereas the Euro and Canadian keep the upper low generally over Texas. So, while there is at least closer agreement...there is still some disagreement and thus we`re back to our talk of uncertainty again. We`re at least confident in the daily chances for showers/storms along the seabreeze throughout the week since we won`t have subsidence aloft suppressing the coverage of convection combined with increasing low-level moisture. As we shift the conversation over to temperatures, let`s briefly talk about our approaching cold front. This front is the result of surface low pressure developing near the ARKLATEX and drifting northeastward early next week. As it does so, the tail end of a weak cold front pushes through Southeast Texas around midweek. I`m keeping that rather vague as timing/progression of this front is still in question. Some models push the front through faster than others, and some are slow on the speed of the front. Either way, the front will at least be close enough to us on Tuesday/Wednesday to allow for moisture to build up along the frontal boundary through convergence, so these will be our best chances to see rainfall north of I-10. With that in mind, it`s definitely easy to see why there is still quite the spread between the lower and upper quartiles (~6+F) of the temperature distribution after midweek. With the upper level low at least nearby, we should see a downward trend in temperatures with highs more commonly in the upper 80s/low 90s towards the end of the forecast period. I know that there is some interest on what could potentially develop in the Gulf next week...so for more details on that, see the Tropical section down below. Batiste && .AVIATION... (18Z TAF Issuance) Issued at 1228 PM CDT Sat Sep 21 2024 VFR conditions are expected through most of the period. SCT mid clouds and SE winds around 5 to 12 kts are expected this afternoon. Higher gusts possible at times. Winds will become light and variable tonight, before strengthening again by midday Sunday. A window of MVFR conditions due to low ceilings and patchy fog will be possible, mainly across our far inland terminals through mid Sunday morning. JM && .MARINE... Issued at 217 PM CDT Sat Sep 21 2024 The benign period of marine conditions continues as light to occasionally moderate onshore winds and low seas will persist into next week. Expect increasing chances for showers/storms beginning on Sunday and continuing into next week. After midweek, winds and seas are expected to gradually climb towards caution flag territory. Mariners should monitor the National Hurricane Center (NHC) for forecasts/updates as a broad area of low pressure is expected to develop in the early to middle part of next week in the northwestern Carribean Sea. This system could then evolve into a tropical depression as it moves across the Gulf of Mexico through the end of next week. It is still too early to determine it`s track, intensity, or any specific impacts from it - but mariners should continue to monitor forecast updates from the NHC through next week. Batiste && .TROPICAL... Issued at 217 PM CDT Sat Sep 21 2024 The National Hurricane Center (NHC) continues to monitor the northwestern Caribbean Sea and southern Gulf of Mexico as a broad area of low pressure could develop by the early to middle part of next week. Gradual development of this system is possible and could result in the development of a tropical depression as it moves slowly northward across the Gulf of Mexico through the end of next week. The NHC currently has a 60% (medium) probability of formation over the next 7 days. This system has not yet developed, so it is still far too early to determine it`s track, intensity, or any specific impacts from it. Don`t put too much stock into any single deterministic model run. Please continue to monitor the latest forecasts and updates from the NHC at www.hurricanes.gov. Batiste && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 73 94 73 93 / 10 10 0 10 Houston (IAH) 75 93 75 93 / 10 10 0 20 Galveston (GLS) 80 87 80 87 / 0 20 10 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...JM LONG TERM....Batiste AVIATION...JM MARINE...Batiste