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 102350 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 550 PM CST Wed Feb 10 2021 .AVIATION [00Z TAF Issuance]... LIFR to IFR conditions will prevail across the area through tomorrow evening with CIGs of 300 to 400 ft and patchy, dense fog. Visibilities below a mile will be possible through tomorrow morning with LBX and GLS having the highest chances of experiencing quarter mile visibility. Scattered showers and isolated thunderstorms develop towards sunrise along the coast, but the main chance of precipitation will arrive tomorrow evening as a reinforcing front slides in from the west. This front will approach CLL in the early afternoon, then slide towards the coast through the evening reaching IAH/HOU around sunset. A line of showers will accompany the frontal passage. Generally northerly winds will persist through tomorrow. Fowler && .PREV DISCUSSION /Issued 418 PM CST Wed Feb 10 2021/... .SHORT TERM [Tonight Through Thursday Night]... The latest surface observations indicate quite a sharp surface temperature gradient across SE TX as a surface cold front continues to gradually sag southward. As of 3PM, the latest 2-meter temperatures measured 39 at Caldwell and 79 at Angleton! Continued moist advection has created an environment conducive for the development of scattered showers and isolated storms today, with this activity expected to continue through the evening hours as the front reaches and clears the coast this evening. Have maintained chance PoPs with the inherited forecast package remaining largely on track. Lows this evening will reach the upper 30s across the Brazos Valley and the 40s to lower 50s across the remainder of the area. As temperatures lower this evening, it`ll likely be the last time we see values over 60 degrees across SE Texas for quite some time as an arctic airmass becomes the dominant synoptic feature over the central CONUS. An amplified 300mb longwave trough will continue to push eastward this evening, with its associated upper jet streak expected to become situated to our north/northeast by tomorrow morning. With SE Texas remaining in the favorable right entrance region of this feature, the resultant enhancement in upper-level divergence will be favorable for more widespread precipitation development during the day tomorrow. With PW values remaining in the vicinity of 1.5 in, showers and isolated thunderstorms should persist through the afternoon and into the evening. The total rainfall forecast remains relatively unchanged with most locations expected to pick up 0.5 - 1.0 in over the course of the day. Cady .LONG TERM [Friday through Wednesday]... Rain chances will be decreasing Fri morning through the afternoon as the cold front pushes well into the Gulf. Strong high pressure building down from the Plains will help to usher in a very arctic air mass into the region at this time with frigid conditions exp- ected to persist through the weekend and and at least through the first half of next week. The other part of the story for the long term portion of the forecast will be the increasing likelihood of wintry precipitation mixed into all of this..lower chances on Sat and perhaps higher chances Sun night/Mon. Global models are continuing to trend cold for the weekend...then even colder during the early part of next week as the strong/amp- lified Arctic surface high is progged to track south in the Great Plains. Did not go quite as low as some of the MOS has suggested, but record lows will be entirely possible. As for rain chances, models appear to be in decent agreement with the timing/strength of these systems. The first shortwave appears to move through SE TX on Sat, but with not so favorable low-level moisture levels and upper support. Did include the mention of ice pellets/sleet and freezing rain for mainly the far northern parts of the FA for Sat morning/afternoon. Otherwise, will be expecting isolated to scattered cold rains. However, things seem to be more favorable for increased POPs for Sun night/Mon. The possible dev- elopment of a coastal low and divergent jet structure aloft along with the strong shortwave are all pointing to much better chances for precipitation. The main question then becomes p-types. Latest guidance indicates that surface temperatures will likely drop to/ near freezing across our northern/western CWA by midnight Sun, so we`ll be starting off with freezing rain/wintry mix overnight. As temperatures continue to fall early Mon, this could transition to more of a snow/wintry mix through Mon morning. And so...the morn- ing commute on Mon could be a very tricky one. Looking even further ahead...guidance not really offering up much by way of warming and/or drying. There are hints of another round of rain/wintry mix for SE TX with the passage of yet another very strong cold front and its associated shortwave. *whew* 41 .MARINE... A surface cold front will push offshore this evening, bringing with it a shift to northerly winds by tomorrow morning. Behind the frontal boundary, an arctic airmass will become dominant over the central CONUS for the foreseeable future, bringing frigid temperatures and the potential for some winter precipitation to the bays and coastal waters. Winds are expected to approach caution and later advisory criteria by tomorrow night, with a further increase in winds expected on Sunday as a developing area of low pressure along the coast significantly tightens the pressure gradient. A Gale Watch may be needed at this time. As this feature pushes into the central Gulf, conditions will be favorable for the development of winter precipitation, with sleet and snow showers remaining a possibility on Sunday night and Monday. The forecast remains relatively uncertain, however, so mariners are encouraged to continue to monitor the latest updates over the next few days. Cady && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 37 43 36 43 36 / 60 80 70 10 10 Houston (IAH) 49 53 42 47 39 / 60 70 80 20 20 Galveston (GLS) 56 59 47 51 43 / 60 70 80 30 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Dense Fog Advisory until midnight CST tonight for the following zones: Galveston Island and Bolivar Peninsula. GM...Dense Fog Advisory until 3 AM CST Thursday for the following zones: Coastal waters from High Island to Freeport TX out 20 NM...Waters from High Island to Freeport TX from 20 to 60 NM. && $$
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