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 142341 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 541 PM CST Thu Jan 14 2021 .AVIATION [00Z TAF Issuance]... VFR conditions are expected to continue through the duration of the upcoming TAF period as mostly clear skies persist with dry air filtering in behind a departing surface cold front this evening. With the front clearing the coast, gusty northwest winds will develop over the next couple of hours before tapering off overnight. Tomorrow, moderate to strong northwest winds return upon the advent of daytime heating. Gusts to around 30 knots are possible at all terminals through the afternoon hours. Cady && .PREV DISCUSSION... /ISSUED 322 PM CST Thu Jan 14 2021/ SHORT TERM [Tonight through Saturday]... A cold front is in the process of moving across SE TX. High pressure will build into West Texas in the wake of the front and this feature will bring a reinforcing shot of cold and dry air into SE TX. Gusty NW winds will settle down this evening except near the coast but there should be enough mixing to limit a free fall in MinT values despite the CAA. On Friday, 850 mb temps will be significantly cooler than today`s values and and MaxT values will remain on the cold side despite full sun. MaxT values will only top out in the upper 50`s. It will be breezy too as stronger winds aloft mix to the surface. Dew points are progged to fall into the teens so RH values will plummet to below 25 percent. There could be some minor fire weather issues with the combination of dry air and strong winds. High pressure will settle over South Texas Fri night into Saturday bringing clear skies to the area. With winds expected to decouple and very dry air over the region, would expect MinT values to really take a dive. MinT values will fall into the lower 30`s with some locations falling into the upper 20`s. 850 temps warm a bit on Saturday and MaxT values will probably warm a few degrees compared to Friday. Winds will be lighter so it`ll probably feel a bit warmer as well. 43 LONG TERM [Saturday Night through Thursday]... Surface ridging will continue to dominate the forecast area Sunday and Monday. Highs will generally be in the 60s, slightly warmer on Monday with highs near 70s across our far southwest counties. The main forecast concern over the extended period will be Tuesday into the end of the week with potential for widespread rainfall and some thunderstorms. Flow pattern aloft begins to be dominated by an amplified closed low over the Desert SW and ridging over the southeast CONUS. At the surface, a gradual increase in moisture advection is anticipated starting on Monday night as a surface low develops over south-central TX. Models, of course, are all over the place on location of the frontal boundary (or boundaries) and the axis of the heaviest precipitation; therefore, uncertainty on details is high. PWAT values are quiet high, near 1.7-2 inches, which is well above normal for this time of year. In fact, the mean precipitable water from NAEFS and GEFS are near 90th percentile of climatology from Wednesday through Thursday. This may suggest the potential for excessive rainfall during this period. Have continued with increasing rain chances starting on Tuesday morning and continuing through Thursday. Depending on the evolution and track of this system, rain chances may linger through Friday. The GFS has been the slowest solution and suggests precipitation through Friday. As of now, have kept rain chances through late Thursday night. 05 MARINE... Southwest winds will continue to strengthen this afternoon and evening ahead of a FROPA currently extending from northeast to south-central TX. Gusts around 20-25 knots have been reported over the Gulf waters with seas between 5 to 6 ft offshore. The front is expected to reach the coastal waters by 6PM this evening. Gusty winds up to 35 knots and seas from 6 to near 8 ft are expected through the night. A Small Craft Advisory is in effect for all Gulf waters and a SCEC for Galveston and Matagorda bays. Wind relaxes early Friday before turning gusty again throughout the day. Given that, SCA headlines will likely be extended. A strong and persistent offshore flow will produce below normal water levels through Saturday. At this time, water levels will briefly fall to around a foot below MLLW late tonight or early Friday. With strong offshore winds persisting on Friday, water levels could fall as much as 2 feet below MLLW and a Low Water Advisory will likely be required Friday night into Saturday. Onshore flow returns Monday afternoon ahead of the next system moving through region Tuesday into Thursday. SCA conditions will be possible with strong winds and elevated seas. Scattered showers and storms are also expected. 05/43 FIRE WEATHER... Have some concerns with regard to fire weather conditions on Friday. Winds will increase with a bit of heating and stronger winds aloft should mix to the surface with sustained NNW winds between 15 and 20 mph with higher gusts. Very dry air will filter into SE TX with dew points falling into the teens. This will create RH values below 25 percent. Normally, under these circumstances, elevated fire weather conditions could be expected but the rain/snow event from last Sunday has left the surface/ground fuels damp so not sure how fast a fire could develop and move. If ground fuels do dry out quicker than anticipated, there could be some issues with grass fires and other fine fuels. Use caution if working with flammable materials on Friday. 43 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 65 36 57 33 59 / 0 0 0 0 0 Houston (IAH) 71 40 59 36 59 / 0 0 0 0 0 Galveston (GLS) 69 46 59 41 59 / 0 0 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...Small Craft Advisory until 6 AM CST Friday 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. && $$
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