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
000 FXUS64 KHGX 212318 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 618 PM CDT Sun Mar 21 2021 .AVIATION [00Z TAF Issuance]... Clear skies and slowly diminishing SE winds to start. Towards dawn, expecting the return of clouds around 3000 feet to return. If winds go light enough, there`s a low chance of CIGs closer to IFR or some patchy fog, but with moisture just beginning to increase this afternoon, leaving any mention out of the TAFs. Expecting some mixing up back for a spell of VFR Monday afternoon, but should degrade again as front approaches the region. Only mentioning rain chances for pre-frontal streamer showers around Houston for now, but will likely have to deal with frontal rains/thunder in the next cycle or two. && .PREV DISCUSSION /Issued 225 PM CDT Sun Mar 21 2021/... .SHORT TERM [Tonight Through Tuesday]... Skies are mostly sunny to partly cloudy across much of Southeast Texas this afternoon, and high temperatures so far are in the mid to upper 60s. We still have several more hours to warm up to our expected highs in the upper 60s to lower 70s. Expect to see increasing clouds develop and move into the area tonight. Winds are expected to stay up enough to keep any significant fog formation from happening, and anticipate low temperatures to range from the low/mid 50s inland to the upper 50s/low 60s coast. A tightening pressure gradient tomorrow (high pressure off to the east and deepening low pressure in/around the TX Panhandle area) will bring increasing and occasionally gusty southeast winds to the area, and gradually rising moisture levels will result in an increase in cloud cover and possible shower development. Better shower/thunderstorm chances will come Monday night through early Tuesday morning as the Panhandle area low lifts out and swings a weak cold front into our area. Any strong/severe storms with this system should be confined to areas off to our northwest Monday night (see SPC`s Day 2 Convective Outlook) where the greatest lift/instability are anticipated. Do not look for any significant cool down with this weak front - lows in the 50s/60s can be expected Monday night and highs close to 80 can be expected on Tuesday. 42 .LONG TERM [Tuesday Night Through Sunday]... With the weak frontal boundary expected to be stalled off our coast Tuesday night, onshore flow will help advect higher PWAT air and the remnant frontal boundary back inland during the day on Wednesday. This combined with daytime heating will keep scattered showers and isolated tstorms along our coastal and southern counties. As another upper-level trough approaches the Southern Great Plains, rain chances will continue to increase for our CWA. Like the previous 00Z run, today`s 12Z deterministic run of the GFS is showing the trough moving through much faster and more shallow than other global models like the ECMWF and Canadian. Therefore, used a blend and weighted the ECMWF more which shows a slower and deeper trough pushing through Texas. Model soundings indicate plenty of mid-level dry air and a moderate cap at 800mb by late Wednesday for our central and southern counties, so keeping isolated, shallow tstorms for now due to slightly suppressive conditions if that cap remains in place on Wednesday. Our northern counties could have a better chance of seeing deep convective storms due to a weaker and eroding cap from 850-700mb and MLCAPE ~1500 J/kg. As that upper-level trough and its associated surface front moves out by late Thursday, global models are varying greatly with their shortwave patterns, so sided with the NBM which shows a dry, warm, and partly cloudy weekend. KBL .MARINE... Light onshore winds will prevail tonight, but will strengthen to Caution or Advisory levels for our offshore waters due to an approaching front. This front will push through late Monday night with showers ahead of the front in our coastal waters as well as showers and isolated thunderstorms along the frontal boundary. This front will stall in our coastal waters by Tuesday morning, continuing rain chances throughout the day. Another front is expected to push through the coastal waters late Wednesday night or early Thursday morning and push out by Thursday night. KBL && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 52 74 57 78 56 / 10 30 70 0 10 Houston (IAH) 56 74 61 80 60 / 0 30 80 10 20 Galveston (GLS) 62 71 64 74 65 / 0 20 60 30 30 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...42 LONG TERM...KBL AVIATION...Luchs MARINE...KBL
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