Area Forecast Discussion
Issued by NWS Houston/Galveston, TXVersions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
604 FXUS64 KHGX 172336 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 636 PM CDT Wed Mar 17 2021 .AVIATION [00Z TAF Issuance]... Moderate westerly winds will become northwesterly going into the evening and overnight hours. Expecting the gusty winds of 20-25 kts to be on and off through the overnight hours for most sites and become a bit stronger tomorrow morning as steep low-level lapse rates extend to 1km. Skies remain clear throughout the entire TAF period. Out in West Texas, an area of dust is moving towards the southeast. Expecting the bulk of this to remain west of our terminals. Lighter amounts of dust have already entered the region, but this is not impacting visibilities enough to mention it in the TAFs. 26 && .PREV DISCUSSION /Issued 326 PM CDT Wed Mar 17 2021/... .SHORT TERM [Through Thursday Night]... High pressure building in across SETX with a round of early Spring very severe weather across LA/MS/AL tonight and Thursday. Weather in SETX should be dominated by clear skies and dry northwesterly winds as a second cold front pushes through the region tonight. Gusty conditions this afternoon and redeveloping inland around 9 or 10 am Thursday. Dewpoints will be much lower with very dry air getting wrapped up into the low to the east from TX and expect afternoon humidity Thursday to park in the 23-40 percent range for most of the area...making for a pleasant afternoon with temperatures only reaching the mid 60s to lower 70s. 45 .LONG TERM [Thursday Night Through Wednesday]... In the wake of this latest frontal passage, NW winds and a high pressure is expected to settle in over our area and bring with it some cooler and drier conditions through the weekend. Daytime highs on Friday and Saturday will be pleasant and near 70. Clear skies during the overnight hours will enhance radiational cooling and bring overnight temps to the 40s and 50s. As the surface high slides to the east and out of our area on Saturday and Sunday, onshore SW winds will resume by Sunday morning. This pattern will bring a warmer and more moist air over our region, helping to increase cloud cover and drive our temperatures up. By Sunday and Monday, daytime highs will reach the mid 70s and overnight lows will be near 60. By Monday, long term models are hinting at the return of rain chances. Onshore flow and an approaching upper-level trough towards our west will aid in theta-e advection, increase our instability, and raise our PWATs to 1.25 inches. The GFS is most aggressive with this onshore flow and shows a decent capping inversion at 850mb, so any convection should be shallow and scattered. By Tuesday, another upper-level trough and surface front should push through SE Texas. The GFS, once again, is being more aggressive than other global models. The GFS shows stronger 500mb PVA, and places the 500mb trough axis further to the east and more negatively tilted than other models. The GFS also places a 250mb jet streak directly over our CWA. All these ingredients lead to a decent surface front developing and pushing across our region. The ECMWF shows a similar pattern, but upper-level support is not as strong and the trough axis is slightly further west, therefore, the surface front pushing across our region is weaker. By Wednesday, both the GFS and ECMWF indicate another shortwave trough and band of precip developing in the wake of Tuesday`s front, but the placement of this precipitation differs greatly. The ECMWF places rain over our CWA whereas the GFS places it over the FL panhandle. Long story short, our next round of rain chances are Monday through Wednesday, with a front passing through our region sometime on Tuesday. KBL .MARINE... Moderate onshore winds will begin to shift to the west and northwest today as a front leaves our coastal waters. Exercise Caution winds will persist through this afternoon for our 20 to 60 nm offshore waters. In the wake of the front tonight, northwest winds and seas will build to Small Craft Advisory Criteria for our offshore waters and Exercise Caution for our bays. Strong offshore winds will persist through at least Friday until a high pressure system settles in. As this high pressure moves east this weekend, southeast winds will resume by Sunday and persist through early next week. KBL .FIRE... Much needed rainfall (0.10-1.0") across the region today though the Matagorda/Jackson county area could have used more given the drought in the west/southwestern counties. Northwest winds in the wake of the cold front tonight will strengthen Thursday morning and will be mixing down some drier air likely bringing RH values down into the 20s across the west so may see some slightly elevated fire weather conditions. Dry air remains firmly parked over the region on Friday with lighter northerly winds. 45 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 45 66 42 68 41 / 0 0 0 0 0 Houston (IAH) 47 67 46 68 46 / 0 0 0 0 0 Galveston (GLS) 51 66 51 67 51 / 0 0 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...SMALL CRAFT SHOULD EXERCISE CAUTION from midnight CDT tonight through Thursday afternoon for the following zones: Galveston Bay...Matagorda Bay. Small Craft Advisory from midnight tonight to 1 PM CDT Thursday 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. && $$
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