736 FXUS64 KHGX 301522 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 1022 AM CDT Sat Mar 30 2019 .UPDATE... Cold front has not yet reached our area, but as it steams coastward, we still look pretty much on track for fropa timing this afternoon. Things do look towards the late end of the window discussed below, and perhaps an hourish later at Houston and the coast. Because of this, I've let highs drift a bit higher at College Station, and a wider band of 80s nearer the coast as they should now get nigh on a full day's warming before temps get cut down. Streamer showers are beginning to crop up here and there in the 2 or so rows of counties near the coast, so I won't muck around with PoPs too much - just some cosmetic changes to sharpen things up around the frontal passage. Speaking of - we look pretty strongly capped, and thunderstorms may be hard to come by. This is particularly true as water vapor imagery suggests we also have a hint of shortwave ridging over the area to erode as well. Because of this, I've gotten a bit more restrictive in handing out thunder, and try to keep it pretty close to the frontal zone, which will have the best shot of overcoming the cap. && .PREV DISCUSSION /Issued 649 AM CDT Sat Mar 30 2019/... DISCUSSION... At 3 AM, a cold front extended from about Tulsa OK to Wichita Falls to south of Lubbock line. The front will move quickly across the state and will probably reach College Station between 17-18z and Houston between 19-20z and then the coast between 21-22z. Clouds and winds have kept temperatures on the warm side tonight and the warm start should allow temperatures to warm to near 80 central/south. Further north, temperatures should still warm to around 70 before falling back to around 60 by late afternoon. Fcst soundings show strong capping in the 850-700 mb layer, At the time of the fropa, a small saturated layer develops between the sfc and 850 mb so there could be some showers along the immediate front with streamer showers beneath the cap well in advance of the front. Not sure there is much of a thunder threat as convective temperatures are in the upper 80s and the cap looks strong enough to hold. Cold air advection will be in full force tonight in the wake of the front on a stout north wind. It will be breezy to windy for much of the night. A Wind Advisory will likely be needed for the immediate coast overnight as sustained winds will likely approach 25 mph. Cirrus will continue to stream into the area tonight but forecast soundings and x-sections don't show much in the way of moisture and PW values fall to around 0.65 inches. Despite the lack of moisture, jet dynamics and mid level forcing still look pretty good. Saturation begins to increase again early Sunday morning along the immediate coast and frontogenesis increases over the SW zones by 12z Sunday. A quick burst of rain will be possible over the coastal counties between 09-15z Sunday but conditions looking less favorable for rain inland. 850 mb temperatures fall from 16 C today to 7 C on Sunday so temperatures will be considerably cooler on Sunday. Bringing the 850 temps down dry adiabatically will support high temps only in the upper 50's. Skies will clear for a time Sunday night but clouds will begin to return early Monday morning. There should be enough clearing to allow for radiational cooling and low temps by Monday morning could fall into the upper 30's over the north and low/mid 40's elsewhere. On Monday a strong short wave will move across the southern plains. The trough looks rather potent yet none of the global models seem very enamored with rain chances. The moisture profile looks dry with the air mass extremely dry below 850 mb but between 18-00z saturation increases in the 700-550 mb layer. Will maintain chance PoPs for now. Skies clear out Monday night and winds will decouple so another night of ideal radiational cooling should allow for another cold night. 850 mb temps stay cold on Tuesday so again daytime high temperatures will remain cool and probably stay below 60 over the north and warm into the lower 60's south. Models begin to diverge on Wednesday as the GFS brings yet another strong short wave across the area with a good chance of rain. The ECMWF is weaker with the trough and generates some light rain over the southern half of the CWA. The Canadian is slower with the trough and brings rain in Wed night to Thursday. Moisture profiles look pretty good Wednesday night and PW values increase to 1.55 inches. Jet dynamics also look favorable with a splitting jet and additional forcing from an approaching 300 mb speed max. Will broad brush with chance PoPs for now. If trends hold, PoPs will need to be raised for Wed night into Thursday. Another strong upper level system will approach next weekend. This system currently looks rather potent and is further south than the past couple of short waves. At this time, this looks like our best chance of appreciable rain in quite some time. 43 .AVIATION... A mixture of MVFR to VFR ceilings across SE TX terminals this morning out ahead of an approaching cold front. Expect ceilings to lower with the frontal passage to MVFR criteria, as a line of showers and isolated thunderstorms slides NW to SE across the region. Anticipate the arrival of the front at CLL between 16-18Z, IAH between 19-21Z, and GLS between 21-23Z. Additionally, we could see some streamer showers out ahead of the actual frontal passage. Not confident enough in potential instability at this time to add VCTS in for any of the terminals, as forecast soundings keep a strong cap between 850-700mb. Strong northerly winds will prevail behind the front with gusts between 25-30 knots at times starting this afternoon and continuing through early Sunday morning. Will see a small break in MVFR ceilings and showers behind the front, but these could return early Sunday morning after 07Z at IAH and southward as showers look to redevelop along the 850mb front. Hathaway MARINE... Small craft should exercise caution in the offshore waters this morning, with wind speeds between 15-20 knots. Winds speeds should diminish through mid morning out ahead of our next frontal passage which should push through the bays between 3 to 6 PM and eventually through our Gulf waters this evening. Scattered showers and isolated thunderstorms will be possible along this boundary. Strong northerly winds will fill in behind the front with winds speeds between 20 to 25 knots increasing to 25 to 30 knots after midnight. Additionally, wind gusts will be between 30 to 35 knots, therefore gusting to gale criteria at times. Bay waters will be rough. Nearshore waters could see seas between 5 to 7 feet with occasional seas up to 8 feet, while the offshore waters could see seas between 6 to 9 feet with occasional seas up to 11 feet behind this front. A Small Craft Advisory has been issued for all waters starting at 10 PM this evening. Winds will remain moderate to strong Sunday morning before beginning to diminish Sunday afternoon. High pressure builds back into the region Monday as winds continue to slacken. Onshore flow returns Tuesday afternoon. Later in the week, there remains the potential for a weak frontal passage Thursday into Friday, but whether or not there is enough upper-level support to push this front through the Gulf waters remains uncertain at this time. Hathaway && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 73 45 57 39 58 / 40 10 0 10 30 Houston (IAH) 78 48 59 42 62 / 40 20 10 10 30 Galveston (GLS) 73 52 59 51 60 / 50 60 30 20 30 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...Small Craft Advisory from 8 PM this evening to 7 AM CDT Sunday for the following zones: Coastal waters from Freeport to Matagorda Ship Channel TX out 20 NM...Matagorda Bay. Small Craft Advisory from 10 PM this evening to 7 AM CDT Sunday for the following zones: Coastal waters from High Island to Freeport TX out 20 NM...Galveston Bay...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. && $$ UPDATE...Luchs DISCUSSION...43 AVIATION...Hathaway MARINE...Hathaway