000 FXUS64 KHGX 161117 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 617 AM CDT Mon Sep 16 2019 .AVIATION [12Z TAF Issuance]... Showers are already beginning along the coast and will continue to impact LBX and GLS through the entire period. The shower activity should spread inland through the afternoon up towards IAH, then there will be a bit of a lull in the evening. However, tonight and through the day tomorrow more widespread showers and thunderstorms are expected bringing occasional low visibilities due to heavy rain rates. Easterly flow today will be a little stronger than the past few days as a large upper level low enters the eastern Gulf. Fowler && .PREV DISCUSSION /Issued 527 AM CDT Mon Sep 16 2019/... .SHORT TERM [Today Through Tuesday Afternoon]... The radar currently is showing shower and thunderstorm activity filling in nicely in the Gulf waters. These storms are driven by the upper level low that has been meandering westward across the Gulf the past couple of days. These showers will continue to spread into the coastal counties later this morning, then up towards I-10 by the afternoon. The more scattered storms combined with more cloud cover will bring daytime temperatures closer normal levels (Galveston may see a day where it doesn't break or tie the daily record high, which it has the past 3 days). The threat of more widespread precipitation over the region increases beginning on Tuesday as the upper level low gets closer to the eastern Gulf. The GFS is driest of the solutions, while the EC and CAN have been trending wetter. There will be some concern that storms along near the coast will produce localized heavy rainfall rates and total, especially as we head into the later part of Tuesday, that raise the threat for flash flooding. Have kept off issuing any flash flood watches at the moment due to lack of confidence, but this could change later today. The threat of heavy rainfall continues to increase through the first part of the long term period. Fowler .LONG TERM [Tuesday Night Through Monday]... Upper low should be sitting off the Matagorda coast with the potential for tropical development Tuesday night into Wednesday morning before it probably moves inland. NAM/ARW are something of an outlier in developing the system faster and more intensely. But that doesn't mean we are out of the woods. Many of the ensembles show falling pressures after the surface low moves inland and wind fields accelerating leading to very efficient rain processes. The rainfall during the day Tuesday should do a great job of getting the soils wet across the southern half of the region. Tuesday night through Thursday afternoon puts SETX in a very favorable region for heavy rainfall with low pressures aloft/tropical/PW 2.1-2.5" and moisture transporting winds 20-30kts. Thanks for the coordination WPC on upping the threat for excessive rain. The system is going to be a slow moving system and widespread rainfall of 3 to 6 inches is going to be common by Friday. Some areas are going to see amounts of 6-9" and isolated amounts in excess of 12" will be possible. Rainfall rates of 2-3"/hr are going to be common during the event. Difficult to narrow down a specific area but all the ingredients are in the mix and will be needing to watch that models don't trend towards a nocturnal consolidating event. Ridging to the north is fairly strong and this system looks to be stuck underneath so wobbles/loops/meanders are probably going to come into play. A Flash Flood Watch looks like a given for Tuesday night and beyond and may be issued tonight or Tuesday morning. On the bright side temperatures should be lower and closer to normal over even slightly below normal for highs with all the precip and cloud cover over the region. The system should start to lift out Thursday with focus for heavy rainfall departing but SETX will still be in the moist axis feeding the remnants of the system so will keep rain chances higher than much of the guidance Thursday night through Saturday. Tide levels should remain elevated through Friday with strong rip currents and possibly minor coastal flooding. 45 .MARINE... The very slow moving upper level low that has been in the central Gulf the past few days continues to meander westward inducing moderate easterly flow through tonight. Thus small craft should continue to exceed caution in the Gulf waters. The moderate flow will also create a continued threat of stronger rip currents today and bring the threat of minor coastal flooding. Will be issuing a Coastal Flood Statement shortly. Onshore flow begins on Tuesday as the disturbance begins to enter the western Gulf/Upper Texas coastal waters. Periods of showers and thunderstorm associated with this system will impact the waters beginning today and continue through midweek with some of these storms producing localized areas of very heavy rainfall and gusty winds. Fowler .CLIMATE... Galveston still setting records as yesterday's 94 degree high temperature tied the old record from 1900. && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 98 74 94 75 90 / 10 20 50 20 60 Houston (IAH) 95 76 92 76 88 / 40 30 70 60 80 Galveston (GLS) 90 80 89 80 86 / 80 80 80 90 90 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...High Rip Current Risk through Tuesday morning for the following zones: Brazoria Islands...Galveston Island and Bolivar Peninsula...Matagorda Islands. GM...SMALL CRAFT SHOULD EXERCISE CAUTION through late tonight for the following zones: Coastal waters from Freeport to Matagorda Ship Channel TX out 20 NM...Coastal waters from High Island to Freeport TX out 20 NM...Waters from Freeport to Matagorda Ship Channel TX from 20 to 60 NM...Waters from High Island to Freeport TX from 20 to 60 NM. && $$