171 FXUS64 KHGX 180957 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 457 AM CDT Tue Jun 18 2019 .DISCUSSION... As the convective weather of recent times calms down, our focus will turn towards potential for late week heat. Temperatures will be decidedly above normal, and a few isolated spots mainly towards Caldwell and B/CS may make a run at triple digits. This will be made possible by modestly drier air. So, while temps are getting very hot, heat headlines are not necessarily a slam dunk at this range. We'll likely have to evaluate the potential for the heat index to exceed 108 each day from Wednesday on into the weekend. A bit of a break from the heat should come later in the weekend as clouds and rain potential will creep back into the picture. .NEAR TERM [Through Today]... Looking at the latest observations and then trying to do a surface analysis of that data proved challenging since there is practically no pressure gradient to analyze. Winds have decoupled inland allowing for temperatures in the low/mid 70s along with dewpoints in the low/mid 70s. Aloft there is a short wave trough over the Texas Panhandle that should continue to move east. There is a weak upper level ridge over Mexico up into the Rio Grande that should also build east as upper level flow increases. Expectation for today will be minimal impacts with a small 10-20 percent chance at a few showers or isolated storm. This should be mainly for the early afternoon northeast of Houston. Shortwave trough axis will be moving by the area but expect there will be little if any lift for storms to form. Overpeck .SHORT TERM [Tonight Through Wednesday]... Jet stream flow does increase over north Texas which puts our forecast area on the subsident side of the jet. Boundary layer flow also veers to the SW which rarely produces a favorable environment for convection as capping should be stronger from the elevated mixed layer. We will need to watch for any lines of storms that form in north Texas that could push into the area. HREF/WRF model runs hint at this possibility. Otherwise the only other weather concern will be the building heat. High temperatures on Wednesday look to reach the mid/upper 90s for much of the area and heat index values could be in excess of 105F as well. Overpeck .LONG TERM [Wednesday Night Through Tuesday]... Heat is the name of the game for the second half of the work week. This may be somewhat surprising if one were to look only at the midlevel height pattern, as it does not strongly suggest big heat. If anything, it looks fairly typical for early summer, with the subtropical ridge in place but not overly strong. I suspect that we have to look lower for our answer. In glancing at the 850 fields, I see flow turning southwesterly with RH below 35 percent on Wednesday, peaking Thursday, then backing off into the weekend. This origin and dryness of the air suggests to me we're getting solid downsloping off Mexican terrain. The drier air should heat up better, and the compressional heating will only boost things. This feels fairly dependent on getting enough shift in the winds to really turn on the torch, and if this doesn't happen, I don't expect we'll get so hot. Still, it seems like every ensemble in the world (literally) has been showing this, and I'm getting a bit tired of fighting it as we draw closer. It probably also speaks that I usually find myself adding degrees to consensus high temps even when weak ridging is in control, but this morning's NBM explicitly gives me a Thursday high of 100 at Caldwell. So...I will channel my inner Dr. Strangelove today and learn to love the blend. Though I just noted I like to add to blended highs in similar setups as it often washes the heat out a bit, I'm going to stand pat with the higher of consensus and our previous forecast to keep continuity. If we really REALLY need to turn the torch on, we've got a few days to nudge our way up there. As it is, the current forecast highs are generally at or above the EPS and GEFS means already, so I don't think we'll have to worry much about falling way short on these highs. Eventually flow should back some more, ending the connection with hot, dry downsloping air. A northern stream trough over the Canadian Rockies may pump up ridging over the Gulf, so rising midlevel heights should keep temperatures from falling too terribly much. However, by the back half of the weekend or early next week, renewed moisture flow from the Gulf...and perhaps even a connection with moisture outflow from a tropical wave (maybe a weak tropical cyclone?) in the East Pacific should help bring potential for showers and storms back to the area. The GFS looks a bit stronger with the ridging, so any Pacific moisture connection happens more to our west. This leaves us a bit drier. The Euro, on the other hand, looks to pump more moisture up into our part of Texas, and is rainier. For now, I'm leaning towards the Euro's solution, but am not selling out to likely PoPs (or higher) just yet. We'll keep things in the chance range and see how this plays out. For what it's worth, NHC has nothing in their 5 day outlook and TAFB shows this as an open wave, and I'm going to trust their forecasting for the East Pacific way before my own. As with the aforementioned temperature forecast, if it turns out we really need to crank things up, we've got plenty of time to ease our way to it. Chance PoPs it is. && .AVIATION [06Z TAF Issuance]... VFR. Patchy fog still possible but with increase in 4000ft and cirrus decks threat trending lower near sunrise. Otherwise no changes. 45 && .MARINE... With high pressure centered just to our east, look for light winds today into tomorrow. While primarily onshore, the light pressure gradient will likely introduce some variability in direction for today. Winds will strengthen Wednesday night both as the surface high moves farther east and a vort max traveling across Oklahoma spurs a surface reflection. Those winds should stay relatively strong into the weekend. Periods of SCEC and small craft advisory conditions can be expected during this timeframe, and significant sea heights look to increase about 2 to 4 feet over the next several days. Showers and thunderstorms won't completely disappear over the next few days, but they should be restricted to being isolated and primarily during the nocturnal period. Rain chances look stronger very early next week, but how rainy things may get appear to be strongly dependent on how effectively a moisture channel can be established with the Gulf, and potentially even a portion of the Eastern Pacific. && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 91 76 96 78 99 / 10 10 10 10 0 Houston (IAH) 93 79 95 79 96 / 10 10 10 0 10 Galveston (GLS) 87 82 89 83 90 / 10 10 10 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ NEAR TERM...Overpeck SHORT TERM...Overpeck LONG TERM...Luchs AVIATION...45 MARINE...Luchs