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 300200 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 800 PM CST Fri Jan 29 2021 .AVIATION [00Z TAF Issuance]... VFR will continue for a few more hours before ceilings begin to lower after 06z and expect BKN/OVC 1400-2000 foot ceilings to spread northeast across the area through 12z. Still a brief window for some fog near the coast at LBX/GLS but at this point with mixing and SW LL flow am expecting it to be more nuisance than big impact. The MVFR ceilings should continue throughout the afternoon eventually improving as prefrontal trough arrives or shortly thereafter. Timing should put the showers into the CLL/UTS areas around 18-22z and then shifting southeast. IAH/HOU around 20-01z with coverage diminishing toward the end with loss of destabilization. Borderline for LLWS prior to the arrival of the prefrontal trough and will be monitoring coming runs for trends with LLWS. CF should arrive around 03-06z/31 at IAH and this should scour out the moisture/clouds though some CI may linger. 45 && .PREV DISCUSSION /Issued 317 PM CST Fri Jan 29 2021/... .SHORT TERM [Today Through Sunday]... Currently, onshore flow and warm theta-e advection will continue to aid in the increase in low-level cloud coverage throughout the day. This flow will also increase our overnight low temps and dewpoints with a noticeable change in the temperatures tonight. Areas north of Houston can expect lows in the mid-50s while everywhere else can expect lows in the upper 50s to near 60 range. Ahead of our next front, southerly flow and cold sea surface temperatures along the coast could aid in sea fog development late tomorrow morning and some coastal counties could be affected by this as well. Any fog should dissipate by tomorrow night as winds switch to an unfavorable direction for for further fog development and dry air begins to seep in behind the front. A deepening trough will push east over OK, NE, and N Texas tonight and its associated surface cold front will also push east towards SE Texas. Despite PWATs slowly climbing to 1.0 to 1.2" ahead of the front, model soundings show a strong low-level capping inversion (850-900mb)and ample dry air above it. Also, with the jet stream located well to our north and becoming more zonal, upper-level support is not favorable for precip as well. Therefore, our CWA can expect scattered showers with no excessive rainfall. Behind the front, cooler and drier air will push through our region, helping to dissipate cloud cover and drop our overnight low temperatures to the mid-50s south of I-10 and the upper 40s north of Houston. KBL .LONG TERM... (Sunday through Friday) Not a whole lot going on in the long term portion of the forecast. On Sunday, surface high pressure will move into the Central Plains in the wake of Saturday night`s cold front. Not a lot of cooling at 850 mb so would expect Sundays MaxT values to warm into the mid and upper 60`s under mostly sunny skies. 850 mb temps cool a bit for Monday and MaxT values should be in the lower 60`s. Moisture profile looks dry so mainly sunny skies expected again on Monday. The surface high will drift wast Monday night with a light onshore flow returning. Could be some patchy fog by Tuesday morning. Upper level ridging begins to develop and expand over South Texas Tuesday and Wednesday. Heights increase and temps at 850 mb also warm. This points to a warm up across SE TX for the middle of next week. MaxT values should warm from the mid 60`s on Tuesday to the mid 70`s by Thursday. A short wave trough will move into the southern Rockies early Thursday and this feature will move toward the Central Plains Thursday night. The upper level trough axis and surface cold front will move through the area late Thursday afternoon or Thursday evening. Could be some isentropic behind the front Thursday night into early Friday as winds aloft remain SW behind the front but that`ll change as the upper trough axis pushes through the area early Friday. A significant drop in 850 temps should correspond to noticeably cooler surface temps for next Friday with MaxT values back down into the lower 60`s. 43 .MARINE... Have issued a SCEC for the Gulf waters tonight as sustained winds are already exceeding 15 knots at buoy 35 and will likely exceed that threshold at buoy 19 later this evening. Winds should increase in response to a tightening pressure gradient as low pressure over the central plains deepens. Winds may decrease after 09z over the nearshore waters as the flow veers to the S-SE as the sfc high drifts east. Winds will veer to the W-SW Sat night as a pre-frontal trough slides through the region. A cold front will cross the area very early Sunday and winds will become NW in the wake of the front and increase to around 20 knots. Another SCEC or possibly an SCA will be required for the Gulf waters in the wake of the front. Surface high pressure will build into the region Sun/Mon and sfc winds will gently veer to the NE and east. Onshore winds will return Tuesday and persist through next Thursday as high pressure drifts east and another area of low pressure develops in the lee of the Rockies. Another cold front will be possible next Friday. 43 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 55 73 47 65 41 / 0 30 0 0 0 Houston (IAH) 54 72 51 67 43 / 0 40 10 0 0 Galveston (GLS) 58 68 57 67 48 / 0 30 10 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 4 AM CST Saturday 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. && $$ AVIATION...45
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