FXUS64 KHGX 070912 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 312 AM CST Thu Dec 7 2023 ...New SHORT TERM, LONG TERM, AVIATION, MARINE... .SHORT TERM... (Today through Friday Night) Issued at 312 AM CST Thu Dec 7 2023 A touch warmer today with the return of southerly winds. Variable high cloudiness into early afternoon will lower and become overcast from west-east during the afternoon and evening hours as low level moisture gradually increases. Considering the thicker cloud cover and steady sse winds, low temps tonight should be a good 15 degrees higher than what we're waking up to this morning. Guidance still likes the idea of some weak shortwaves moving into the area from the west late tonight and Fri. Assuming PW's climb as forecast, we might see some iso-sct shower development (better chances across the southern half of the CWA)...eventually pushing off to the east late Friday afternoon & evening with the departure of the upper disturbance and higher PW axis. Hires models aren't as bullish with coverage as some of the global models. Overall, left POPs about where they were advertised with earlier fcst packages. 47 && .LONG TERM... (Saturday through Wednesday) Issued at 312 AM CST Thu Dec 7 2023 Going into Saturday, the surface low that subsequently develops from a mid/upper trough sweeping through the Central CONUS will be moving quickly to the NNE into the Great Lakes region as it rides along the upper level wind pattern. Since the movement of this low is more northerly than easterly, the associated cold front will take a bit longer to push through. Think of it as the front gets caught in traffic coming down I-45...I'm sure we all can relate. Model consensus (including some high-res guidance) points toward a mid to late afternoon FROPA for most. It's too early to give a super precise timeframe, but in general it's looking like the front begins to move into the Brazos Valley around 1-4pm and doesn't push offshore till around or after 9pm. There remains "some" potential for strong to severe storms to develop along and ahead of the frontal boundary given the abundance of shear (0-6km shear greater than 60 kts) and an axis of instability (MUCAPE 1200-1800 J/kg) within the warm sector of the surface low...but there's something that will likely hinder our chances of seeing these stronger storms. With an 850mb high off to our east providing southwesterly flow throughout most of the week ahead of the approaching front, a fairly robust subsidence inversion layer (cap) will be in place around 850-750mb. Check out some of the forecast soundings and you'll see it's fairly sharp...so that'll be tough for storms to overcome. That's not to say that storms can't break the cap...but the odds look to be more in favor of the cap holding. All that being said, SPC has kept parts of Southeast TX in a marginal to slight risk of severe weather on Saturday. Generally, areas along and east of I-45 are in the slight risk...but the best chance of seeing strong to severe storms will likely be in the Piney Woods (northeast counties). Confidence in rainfall in general occuring is fairly high though, and some locally heavy rain will be possible as well along the front with PW values surging up to 1.4"-1.6" (90th percentile: ~1.44"). There are no concerns for flooding. With the cold front now moving through more in the mid to late afternoon time frame, that allows more time for southwesterly winds ahead of the front and compressional heating to get temperatures into the mid to upper 70s on Saturday afternoon. Some areas may even reach the 80°F mark...that'll make the 12 hour temperature difference that much more drastic. Behind the front, strong CAA will prevail with northwesterly winds around 20-25 mph and gusts of 30-35 mph. A Wind Advisory may be needed for parts of Southeast TX Saturday evening into Sunday morning. So, if you have any outdoor holiday decorations up (especially inflatables), you'll definitely want to make sure they are secured...it is the season of giving but let's not give accidental decoration donations to your neighbors down the street. PW values drop sharply behind the front reaching less than 0.2" by Saturday night, which is near the climatological minimum. Gusty winds overnight will keep temperatures from dropping as much as they could...but we'll still see a 30-40°F drop from Saturday afternoon with lows in the upper 30s to low 40s. Surface high pressure moves overhead on Sunday as daytime highs only climb into the mid to upper 50s. With clear skies and light winds overnight on Sunday, we have the perfect recipe for maximum radiational cooling...so I nudged temperatures down a bit below guidance. Expecting widespread low temperatures in the 30s with parts of the Brazos Valley/Piney Woods experiencing a light freeze. With a 850mb high remaining overhead into Tuesday, 850mb temperatures remain around the 10th percentile. So, although high temperatures will increase...they'll only increase to the low to mid 60s. Surface high pressure slides off to the east by Tuesday leading to return flow increasing PW values back to 1.0"-1.3" off the coast by Tuesday night. That leads to rain chances returning generally south of I-10. Midweek looks rather...interesting to say the least. Another mid/upper level trough moves from the NW CONUS down towards the Four Corners on Tuesday. There is model consensus on this becoming a cutoff upper level low that remains in the SW CONUS past midweek. If you read last night's AFD then you'll remember that there was talk of a potential midweek cold front...well that would be postponed in this scenario if it verifies. This is a good example of why we don't set things in stone a week out...each model run could (and likely will) show something different at that range! The good news is that model guidance has been very consistent on keeping temperatures generally in the 60s for highs and the 40s for lows into next week. Batiste && .AVIATION... (12Z TAF Issuance) Issued at 312 AM CST Thu Dec 7 2023 VFR today and into overnight hours. As high pres departs further eastward, llvl flow will transition to a more sly direction and bring a gradual return of increased moisture levels. Look for 3-5kft ceilings to make their way in from the west later this afternoon and into the I-45 terminals 0-3z. From there, expect them eventually to fall into MVFR territory after about 9z...and maybe even some higher end IFR around CLL around sunrise Friday. 47 && .MARINE... Issued at 312 AM CST Thu Dec 7 2023 Onshore flow returns later this morning and begins to strengthen going into tonight and Friday as the next weather system approaches. Winds may reach the caution threshold as early as tonight and will be fairly close to the advisory threshold Friday afternoon into Friday night. As a result of the strengthened onshore flow, the risk of rip currents will also be elevated on Friday. A strong cold front will push through the waters late Saturday with moderate to strong northwesterly winds in its wake. Mariners can expect at least a Small Craft Advisory to be in effect from Saturday evening into Sunday morning. Wind gusts to gale force will be possible in the Gulf waters. Due to the elevated offshore flow, low water levels will be possible in the bays during low tide on Sunday morning. Wave heights also increase due to the strong offshore flow and peak in the 7-9 foot range on Saturday night/Sunday morning. Winds and seas gradually subside on Sunday with onshore flow returning by Monday afternoon. Batiste && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 71 61 76 67 / 0 10 10 10 Houston (IAH) 70 59 76 68 / 0 20 30 10 Galveston (GLS) 67 63 71 67 / 0 10 30 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...47 LONG TERM....Batiste AVIATION...47 MARINE...Batiste