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
157 FXUS64 KHGX 080012 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 612 PM CST Sun Feb 7 2021 .AVIATION... Low pressure will develop over NW TX and onshore winds will persist for the TAF period. Low level moisture will begin to return beneath a capping inversion. A mix of VFR/MVFR ceilings is expected to develop over mainly the northern TAF sites on Monday morning. Ceilings will persist for much of Monday before scattering out between 22-01z. SE winds will persist and increase slightly as stronger winds aloft mix to the surface in the afternoon. 43 && .PREV DISCUSSION... /ISSUED 334 PM CST Sun Feb 7 2021/ DISCUSSION... The early part of the forecast keys in on the return of Gulf moisture from onshore winds ahead of a midweek cold front. We could see patches of fog in typical problem spots, but more widespread fog is a possibility tomorrow night. As dewpoints and moisture increase, it will provide fuel for high precip chances ahead of and with the front, tentatively scheduled for late Wednesday night into Thursday morning. Instability looks high enough that we`ve added potential for some isolated thunderstorms on the warm side of this event, but the big questions come on the cold end, and if the incoming cold air will arrive with enough moisture to change over the last bit of rain to something more frozen. Confidence is such a borderline case at five days out is unsurprisingly pretty low, but the trend seems to be that Southeast Texas will stay too warm for measurable frozen precip. But, the high uncertainty brings with it the caveat that there is still plenty of time for expectations to change, so keep up with the forecast this week. SHORT TERM [Through Monday Night]... Sunday is true to its name today, with a very nearly clear sky across the area. Temperatures are only in the 60s though, thanks to the low February sun angle (excepting a couple reports in the upper 50s very near the Gulf thanks to cool water temps). Still, that makes for a seasonably pleasant day for Southeast Texas. Winds are southeasterly to southerly already this afternoon, and increasing dewpoints with the onshore winds are expected to keep overnight lows up in the 40s and 50s tonight, as opposed to the 30s and 40s we`ve seen for low temperatures recently. We`re pretty early in our moisture return process, and winds aren`t really expected to go slack overnight though, so while there are some hints of patches of fog here or there possible, we should probably instead look for the development of some lower stratus clouds very late tonight into tomorrow morning. The higher temperature floor means Monday looks to be warmer, and see several spots crack back into the 70s in the afternoon. Just how much of the area reaches 70 will depend on cloud cover, and since I`m reasonably pessimistic about sun on that front, the boost in forecast highs is just a modest one. As low level moisture continues to increase, and with a better shot at seeing winds go slack in the overnight hours, widespread fog will have a better shot at cropping up late Monday night. Some of the guidance is getting pretty aggressive with the visibility reductions in that fog, but that`s kind of long range for reliably good forecasts of visibility, so I`ll stick to sketching out a rough extent of areas where fog potential is higher. Of course, another alternative is that we`ll see enough isentropic lift of the Gulf air that we could see pre-dawn streamer showers. While it`s certainly another plausible scenario, collaboration among the upper/middle Texas coast offices leads to favoring fog at this juncture. LONG TERM [Tuesday Through Sunday]... A persistent onshore flow Tue and Weds will be keeping temperatures on the mild/warm side for a much of SE TX. While the zonal pattern aloft will be helping to keep the cold front just north of the CWA on Tue, there are some hints that the passage of a few upper level disturbances (via the southern stream jet) could nudge this bound- ary a bit into our northern zones very briefly late Tues afternoon. But that being said, will err on the side of warm and keep daytime highs mostly in the 70s for inland locations both Tue/Weds at this time. Lows are expected to range from the 50s inland to near 60 at the immediate coast. Rain chances will also begin increasing Weds given this heating as well PWs climbing to 1.3-1.4" and progs of a decent low-level jet. These elevated POPs are expected to continue into Weds night/Thurs with the arrival/passage of the cold front across SE TX. Even with global models remaining sharply divided with regard to how cold we will get, FROPA timing is trending a little better. That is, we`ll be looking for the wind shift to reach the coast Thur afternoon or evening per these latest runs. Did include the mention of isolated thunder in the grids for this time period given the progged sound- ings of some decent CAPE. As the very cold air mass moves into the region behind this front, a much colder forecast is on tap through the rest of the week. Daytime highs Fri/Sat could struggle to make it into the mid/upper 50s (..and possibly into Sun). We could also see our coldest temperatures of the season for both Fri and/or Sat nights. Currently going with overnight low temperatures in the mid to upper 20s over the northern third of our CWA...at/around freez- ing for central locations...upper 30s for the coastal counties for this time period. MARINE... Generally light/moderate onshore winds have returned to the marine waters this afternoon...and will be expecting this pattern to per- sist into the first part of the week. However, this pattern appears to also favor the possibility of patchy sea fog developing by late Mon into Tues/Weds ahead of the next cold front. Current forecasts have this boundary moving into the coastal waters Thurs afternoon/ evening with moderate to occasionally strong offshore winds as well as rough seas developing in its wake for the rest of the week into the start of the weekend. Small Craft Advisories will be likely by Thurs. && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 48 72 56 75 54 / 10 10 10 0 0 Houston (IAH) 48 70 57 76 59 / 0 10 10 10 0 Galveston (GLS) 55 67 61 69 62 / 10 10 10 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ Discussion...99 Aviation/Marine...99
No comments:
Post a Comment