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 082338 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 538 PM CST Fri Jan 8 2021 .AVIATION [00Z TAF Issuance]... The pesky 3000ft cloud deck that has been over the northern half of the region all day has finally began to erode and should scatter out completely over the next few hours. So MVFR conditions will be possible at CXO, UTS, and occasically CLL through midnight, but then clear skies should emergy. VFR conditions will then continue through the rest of the period with the winds becoming light overnight and turning southeasterly through the afternoon tomorrow. High clouds begin to stream into the area from the west tomorrow afternoon as well. Fowler && .PREV DISCUSSION /Issued 414 PM CST Fri Jan 8 2021/... .SHORT TERM [Today Through Saturday Afternoon]... Mostly pleasant weather in place over the area with lingering cloudiness over the northeastern half of the region though steadily eroding. Northerly flow keeping it cool though and overnight expect temperatures to fall into lower 30s well inland to the mid 40s on the immediate coast. An upper level low over North Carolina and WNW flow aloft over Texas with two low pressure systems over Pacific NW and Srn CA will become our big weather maker this weekend. Saturday here should be similar today but with more sunshine in the morning then going into the evening the skies should begin to cloud up as first high clouds overspread the region with the two low pressure system starting to phase up over NM/Nrn Mexico. 45 .LONG TERM [Saturday Night Through Friday]... A complex precipitation event bringing the first threat of accumulating snowfall in around two years to the greater Houston area will take place towards the end of the upcoming weekend. Confidence has increased in the possibility of snowfall totals of 1 to 3 inches across the northern third of the area, though the chance for locally higher totals remains due to the potential for frontogenetically enhanced snow banding on Sunday night. As an upper trough digs into the Four Corners region by Sunday while upper-level support from a jet streak over central Mexico will induce cyclogenesis along the southwestern Gulf Coast. While the associated surface boundary pushes towards the northern edge of the area, a coastal low pressure system will track northeastward towards SE Texas. PWs rise into the vicinity of 1 - 1.25in by Sunday afternoon, with precipitation initiating as rain across the area during this time. With temperatures dropping as the surface boundary progresses through the region, a changeover to snow or a rain-snow mix across the northern third of the area is expected by late afternoon. The greatest threat for accumulating snowfall continues to be the overnight hours of Sunday. Global models still painting different pictures regarding p-type and overall totals, though confidence is higher in at least some accumulation across the northern zones. 850mb temperatures continue to show a drop-off to around -2C or below by Sunday evening, and forecast soundings continue to show a well-saturated column below the freezing line across the northern third of the area. GFS remains the least aggressive solution with minimal accumulation, while 00Z EC continues to maintain widespread 1-3" totals north of the I-10 corridor. Latest NAM runs have continued to show a potentially concerning trend in depicting a strong area of mid-level frontogenesis and thereby some locally heavy snowfall totals across the northern zones. In considering all available model data and latest trends, have opted to forecast 1 to 3 inch totals generally north of SH-105 though the possibility of locally higher amounts is possible depending on mesoscale forcing. South of I-10, a cold rainfall will persist through the entire event with some locally heavy downpours and minor flooding in low-lying and otherwise flood- prone areas is possible. Precipitation should taper off by late Monday morning as the coastal low shifts into the Central Gulf. In the wake of the departing front, a period of quieter and colder weather is expected with daytime highs in the mid-50s to lower 60s and overnight lows near freezing through the middle of next week. With high pressure becoming the dominant synoptic feature, no additional rainfall/snowfall is expected through the middle of the coming week. Cady .MARINE... Northerly winds tonight becoming easterly Saturday afternoon and night then strengthening as a low pressure system starts to develop over South TX and eventually moving into the Coastal Bend region Sunday morning then pushing east through the Upper Texas Coastal Waters late Sunday. Hazardous marine conditions will develop with strong east and southeast winds building seas along with rain and lowered visibility. SCA conditions are likely Sunday through Tuesday morning and may even flirt with near gale. Seas building to 8 to 13 feet offshore and with the earlier easterly winds tide levels will rise and as of now it appears the window between 9 am Sunday and 7 am Monday tide levels may rise high enough to cause beach flooding. The associated cold front sweeps offshore late Sunday and winds strengthen out of the north then gradually relax late Monday. 45 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 34 53 39 43 30 / 0 0 20 90 60 Houston (IAH) 37 55 41 46 37 / 0 0 20 80 90 Galveston (GLS) 44 54 48 53 42 / 0 0 20 80 90 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Winter Storm Watch from Sunday afternoon through Monday morning for the following zones: Brazos...Burleson...Grimes...Houston...Madison...Trinity...Walker...Washington. GM...Low Water Advisory until 9 AM CST Saturday for the following zones: Galveston Bay. && $$
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