Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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366 FXUS64 KHGX 170446 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 1146 PM CDT Sun Jun 16 2024 ...New AVIATION... .SHORT TERM... (This evening through Monday Night) Issued at 257 PM CDT Sun Jun 16 2024 As we head into the beginning of the upcoming week, we will enter into a period of active weather that will be characterized by widespread, occasionally heavy rainfall which could lead to flooding along area rivers, streams and bayous as well as some street flooding. Global models continue to show cyclogenesis in the Bay of Campeche overnight tonight, likely leading to the development of a weak closed low by the early hours of Monday. This feature, as well as a developing lee cyclone to our northwest, will produce a tighter synoptic pressure gradient and thus a stronger onshore flow regime that will bring a plume of deeper tropical moisture to the area. With an associated midlevel trough providing some vorticity advection along with the impacts of diurnal heating, we will begin to see shower/thunderstorm activity pick up across the area overnight into the early hours of tomorrow and expand in coverage during the afternoon. Any stronger storms that develop will have the potential to tap into relatively deep moisture (PWs > 2.0 in by Mon afternoon) and produce some locally heavy downpours. As such, the WPC has maintained a Slight Risk of Excessive rainfall roughly along and south of the Hwy 59 corridor. Urban and poor drainage areas may see some localized street flooding depending on the location of any stronger developing storms. Otherwise, rainfall totals will generally sit around an inch south of the 59 corridor and less across the northern zones. Temperature wise, increasing cloud cover along with the impacts of afternoon rainfall may keep highs from exceeding 90 for much of the area, especially closer to the coast. Despite this, dew points in the mid 70s will still contribute to heat stress as heat indicies once again reach the century mark. Overnight lows, bolstered by WAA and greater cloud cover, will sit in the mid to upper 70s inland and near 80 along the coast. Cady && .LONG TERM... (Tuesday through next Saturday) Issued at 257 PM CDT Sun Jun 16 2024 A closed low is expected to develop in the Southwestern Gulf by Tuesday. Combined with high pressure/ridging spanning the eastern sea board, this will greatly tighten the pressure gradient, setting up a 30-40 knot LLJ over portions of the Texas/Louisiana coast. Converging winds along the coastline & forcing from this system, in combination with deep moisture (PWs in excess of 2" at times), will result in numerous storms across the Northwestern Gulf throughout the first half of the week. Forecast soundings during this period feature deep saturation, with a warm cloud layer in excess of 15,000 ft, still indicative of high precipitation efficiency necessary to produce heavy rainfall. WPC has a Moderate (level 3/4) to Slight (level 2/4) Risk of excessive rainfall over SE Texas for Tuesday through Wednesday. These storms will be capable of producing heavy rainfall, with areas south of US-59 most at risk for heavy rains and flooding (denoted by the Moderate Risk area). This includes the Houston Metro area, with urban locations such as these already prone to flooding due to poor drainage. Areas south of US-59 could see rainfall totals of 5-8 inches with isolated higher amounts possible. Areas to the north will generally receive 2-4 inches during this same period. This rainfall will likely result in rises in rivers, streams and creeks. Additionally, strong winds and long fetch induced by this system may result in moderate coastal flooding as well. Some uncertainties still remain in the forecast, mainly with the track of the system. It`s important to remember that even small deviations in the expected path of this system can greatly shift where the heaviest rain falls. Regardless, confidence in tropical development is growing, and NHC now has a 70% chance of this system becoming a tropical cyclone within the next 7 days. Impacts from this low will still be felt across SE Texas, regardless of if it becomes a named cyclone. The heavy rainfall threat diminishes on Thursday as the aforementioned system tracks into Mexico and dissipates. However, wet conditions look to continue through the end of the week as a broad upper level low traverses through the Gulf of Mexico. An upper level high over portions of the Southern Plains looks to keep that next disturbance restricted to the Southern Gulf, thus limiting it`s impacts to SE Texas. 03 && .AVIATION...
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(06Z TAF Issuance) Issued at 1145 PM CDT Sun Jun 16 2024 VFR conditions for the most part overnight. There are some spotty shra near the coast, but look for a bit more coverage as we head into sunrise...eventually spreading inland as the day progresses. Difficult to narrow down the most favorable timing for the TAF sites...as the precip will probably be coming in intermittent band/waves with periods of rain & no-rain. We should get somewhat of a break in activity in the evening and overnight Monday followed by higher chances on Tues. 47
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&& .MARINE... Issued at 257 PM CDT Sun Jun 16 2024 Winds and seas will increase over the next several days as the pressure gradient tights from a developing low over the Southwestern Gulf of Mexico. Ample Gulf moisture will bring numerous showers/storms daily, beginning later tonight into the upcoming week. Small Craft Advisories take effect on Monday and will likely be extended over the next several days as winds approach 20 to 30 knots with gusts in excess of Gale-Force possible. Seas are expected to reach 10 to 15 feet at times. These strong onshore winds over a long fetch will also bring a high risk of rip currents and potentially moderate coastal flooding across the Texas coastline as early as Tuesday. Forecasted winds and seas may vary depending on how this system evolves. Gale warnings cannot be completely ruled out at this time. Stay tuned over the next several days as we monitor this system. Conditions begin to improve on Thursday as the aforementioned tropical system dissipates over Mexico, with winds and seas falling below Small Craft Criteria on Friday. 03 && .HYDROLOGY... Issued at 408 PM CDT Sun Jun 16 2024 Ongoing river flooding persists for a few sites along the Trinity River. The Trinity River near Liberty continues to gradually rise in moderate flood stage and may crest into major flood stage later this week. The Trinity River at Riverside crested in moderate flood stage, but will take a while to recede. The Trinity River at Moss Bluff continues on a slow and gradual climb in minor flood stage. The current forecasts do not take into account the upcoming rainfall event later this week. We are continuing to monitor an area of disturbed weather currently over the Yucatan Peninsula that is expected to become a broad surface low in the Bay of Campeche (southwestern Gulf of Mexico) over the next few days. This low would then have the potential to become a tropical depression by midweek as it moves slowly westward or west-northwestward. REGARDLESS OF TROPICAL DEVELOPMENT, the deeper tropical moisture from this system will bring periods of moderate to heavy rainfall for portions of Southeast Texas (mainly areas near and south of I-10). Tuesday into Wednesday in particular look to be the main days with heavy rainfall potential. Locally heavy rainfall may lead to localized instances of street flooding in some areas. Forecast uncertainty remains rather high though, but for now we`re continuing with the messaging of 5-8" of rainfall near and south of US-59/I-69 and 2-4" north of US-59/I-69. That total rainfall forecast is over a four day period from Monday-Thursday. New river flooding will be possible as early as Tuesday. We`ll also be monitoring for the potential for flooding along area creeks and bayous as well. With there being general consensus for the higher end of the rainfall amounts occuring near/along the coast, this will be beneficial rainfall for drought stricken areas (mainly those near Matagorda Bay). Remember to heed any instructions from your local officials and to never travel through ANY flooded areas or roadways. TURN AROUND, DON`T DROWN. Please monitor updated forecasts via the NWS NWPS webpage (https://water.noaa.gov/). Batiste && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 76 91 75 89 / 0 50 0 30 Houston (IAH) 77 89 75 84 / 10 60 20 70 Galveston (GLS) 80 88 80 86 / 40 70 50 80 && .HGX WATCHES/WARNINGS/ADVISORIES...
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TX...High Rip Current Risk from 10 AM CDT Monday through Tuesday morning for TXZ436>439. GM...Small Craft Should Exercise Caution through Monday afternoon for GMZ330-335-350-355-370-375. Small Craft Advisory from 1 PM Monday to 7 AM CDT Tuesday for GMZ330-335-350-355-370-375.
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