044 FXUS64 KHGX 091849 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 149 PM CDT Tue Oct 9 2018 .AVIATION...[18Z TAF] SHRA/-TSRA expected to continue to develop across the forecast area this afternoon. Passing SHRA/TSRA expected to continue north of IAH/CXO through around 10/02Z. BR and low ceilings could develop again overnight particularly across CLL/UTS/CXO/IAH ahead of a frontal boundary and is expected to dissipate after 15Z. Winds will shift from the southeast to northwest overnight through Wednesday. && .MARINE... Based on the NHC Bulletin [1 PM CDT], Hurricane Michael was located near latitude 25.4 North, longitude 86.4 West and is forecast to strengthen as it continues to move northward toward the Florida Panhandle. Long period swells generated by Michael will continue to move across the Gulf of Mexico through mid week, thus, building seas up to 5-7 feet with occasional seas up to 8 feet are anticipated mainly across the offshore coastal waters tonight and Wednesday. A Small Craft Advisory was issued this morning for the offshore waters and will be in effect starting at 9 PM CDT tonight. Small craft should exercise caution across the nearshore waters for seas up to 5 feet. Winds will shift to the northwest overnight and will range between 5 to 15 knots with higher gusts on occasion. The combination of the swells and winds will continue to produce minor coastal flooding especially during high tide, as well as moderate to high rip current risk. && .PREV DISCUSSION... /ISSUED 1121 AM CDT Tue Oct 9 2018/ UPDATE... Quick update to add possibly severe to the western and northwestern counties mid-late afternoon. HRRR trends indicate the threat may briefly extend in the evening hours but still have time to make any changes there later depending on how the afternoon convection develops. 45 PREV DISCUSSION... /ISSUED 1033 AM CDT Tue Oct 9 2018/ UPDATE... Convergence getting stronger across the southeastern areas Liberty/Chambers counties through the Sabine Pass area and have increased rain chances this morning and afternoon in the eastern areas. Second moist axis with 2.0" pw spreading into the Matagorda Bay area as well though LL convergence isn't as strong there. Main axis of precipitation from near Del Rio to Kerrville to Hillsboro with strong to severe thunderstorms along the line. This band should continue to move east today and as it nears the western portions of SETX late afternoon may see a strong thunderstorms in the northwestern areas. Have made some adjustments to the pop/temps for the expanded cloud cover and current short term trends. Minor coastal flooding continues and still have a couple more high tide cycles to go before these drop. Even seeing impacts to the bay side of Galveston island. Swells arriving near 42035 and periods are getting longer today. Rip currents already strong and will probably get stronger today and Wednesday. 45 PREV DISCUSSION... /ISSUED 649 AM CDT Tue Oct 9 2018/ AVIATION...[12Z TAF] LIFR/IFR BKN/OVC ceilings have developed over KCLL/KUTS/KCXO and KIAH which should transition to MVFR for a couple hours this morning as mixing increases in the boundary layer. Atmosphere should still support SHRA/TSRA but coverage should be similar to the last couple of days so will use VC instead. Possible that fog and low ceilings could develop again overnight ahead of a frontal boundary. For now kept TAFS MVFR after 06Z/10th with wind shift occurring just beyond the TAF period except for IAH 30 hr TAF. Overpeck PREV DISCUSSION... /ISSUED 411 AM CDT Tue Oct 9 2018/ Short Term/Aviation... It was 81F at 1AM here at the forecast office. That tells me it is still nasty humid and surface dewpoints in the upper 70s only confirm it. Surface analysis shows a decent pressure gradient to support E to SE winds which in some areas have decoupled. MVFR and even IFR ceilings will be possible mainly for areas north of Houston but still possible that MVFR ceilings could develop farther south. There is some shower activity in the Gulf with the warm advection pattern but it will again take diabatic heating for showers and storms to develop today. SPC mesoanalysis and GOES 16 precipitable water imagery show values around 2 inches or more west of I-45 with a axis of lower moisture over east Texas into the Gulf. Most of the shower and thunderstorm activity should remain embedded within areas of higher moisture. Higher moisture from Hurricane Michael could reach the area later today/tonight ahead of an approaching frontal boundary. Overall think any convection will be widely scattered like yesterday so TAFs will likely have VCSH/VCTS with a more linear line of storms possible this afternoon/evening if WRF/HRRR trends are on track. Short term forecast will hinge on this evolution and the frontal boundary pushing through Wednesday. Assuming skies clear in the evening there could be another set up for fog Wednesday morning before the drier air behind the front arrives in the region. Overpeck Discussion... Showers and thunderstorms are expected into the overnight hours tonight along and ahead of an approaching Pacific cold front. The cold front should push through the area early Wednesday morning, with conditions clearing out during the day Wednesday as dry air pushes in. Hurricane Michael will remain well to the east of us but will help drag the cold front through rather quickly and push even more dry air overhead from being on the subsident side of the storm. Since this front is a Pacific front, high temperatures may come down a few degrees, but the noticeable change will come from the low humidity and much lower low temperatures. Generally dry and warm conditions are expected until this weekend. Winds gradually come around to onshore again Friday night, giving us some moisture return before the next cold front on Sunday. This second front will be much more of an autumn front with both dry and much cooler conditions expected in the wake of it. Expect high temperatures in the mid 60s to low 70s early next week with lows in the 50s to low 60s. 11 MARINE... Surface analysis is showing low pressure over W Texas and high pressure over the New England States which is allowing for east to southeast winds this morning. Hurricane Michael is also supporting easterly winds across the northern Gulf. This should generated higher periods swells which will increase wave heights tonight going into Wednesday. For now think continuing SCEC for the offshore waters will be the way to go since both winds and seas are still just below SCA criteria. The first of 2 frontal boundaries will push off the coast late Wednesday into Thursday turning winds offshore. A stronger front is expected over the weekend and may require advisories. Coastal flood advisory continues through Wednesday morning and may need to be extended through Wednesday night. This will largely depend upon how much higher period swells influence tides and when those swells stop. The swells could push tides higher than expected so possible that a coastal flood warning could be needed. For now levels look to remain consistent with an advisory and will continue that today and tonight. The higher wave action may also produce strong and hazardous rip currents. We will issue a beach hazards statement to cover the threat of strong rip currents and wave action on areas beaches. Overpeck && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 85 70 83 60 80 / 90 60 20 0 0 Houston (IAH) 86 74 86 63 82 / 60 50 20 0 0 Galveston (GLS) 86 78 86 72 81 / 40 40 20 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Coastal Flood Advisory until 7 AM CDT Wednesday for the following zones: Brazoria Islands...Chambers...Coastal Brazoria...Coastal Galveston...Coastal Harris...Coastal Jackson...Coastal Matagorda...Galveston Island and Bolivar Peninsula...Matagorda Islands. GM...SMALL CRAFT SHOULD EXERCISE CAUTION through Thursday morning 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. Small Craft Advisory from 9 PM this evening to 9 PM CDT Wednesday for the following zones: 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. && $$ Discussion...24 Aviation/Marine...45