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 240549 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 1149 PM CST Wed Dec 23 2020 .AVIATION [06Z TAF Issuance]... With the cold front currently moving into the coastal waters, strong/gusty N/NW winds have developed across the CWA behind the cold front. Based on upstream obs, will keep these winds in place until sunrise or so, lowering them a bit for inland sites through tomorrow afternoon. However, this strong/gusty offshore flow should persist along the coast (mainly for GLS and to a lesser extent at LBX). Surface high pressure build- ing into the region will help lower winds tomorrow night and shift them more to the west. Otherwise, the mid/high broken/ overcast decks trailing the precipitation should continue to track E/SE overnight. VFR skies to prevail. 41 && .PREV DISCUSSION... /ISSUED 444 PM CST Wed Dec 23 2020/ SHORT TERM [This Evening through Thursday Afternoon]... A strong upper level trough will continue to scoot eastward and move across the Great Plains through Thursday. Along the surface, a low pressure system will then shift east into the Great Lakes region and the associated cold front, extending all the way into central TX, will move into SE Texas this evening and tonight as high pressure builds over the Rockies. The added lift from the cold front along with the southerly wind flow and moisture transport (PWATS of 1.0 to 1.5 as of 3 PM CST) will continue to induce a favorable environment for the development of showers and thunderstorms ahead and along the boundary. Strongest activity is still expected to occur across the SE quadrant of the CWA, possibly extending a little more north into the eastern counties. The stronger activity could be accompanied by periods of heavy rainfall, strong gusty winds and small hail. Some weak rotation could also occur, but at this time the probability for tornadic activity is very low (2%). The cold front is expected to move across the region rather quickly, moving into the coastal waters before midnight CST. Once the front passes through, rain will cease and a much drier air mass will settle across the region with dewpoints dipping into the 15-25 deg F range by early Thursday morning. Low temperatures tonight will dive into the mid to upper 30s along areas north of I-10 and the upper 30s to low 40s along areas south of I-10. High temperatures on Thursday will stay in the refreshing 50s and skies will be nice and sunny as high pressure builds...perfect day for some hot chocolate. 24 LONG TERM [Thursday night through Wednesday]... Low temperatures on the night of Christmas Eve will range from the low 40s along the coast to the low to mid 30s further inland, so Santa Claus will have suitable conditions for his journey across Southeast Texas. The area of high pressure that followed the previous cold front will continue moving towards the southern tip of Texas and by Friday afternoon begin moving northeastward along the coast. This will bring westerly winds into the area which puts an end to the CAA. High temperatures across the area on Christmas Day will reach the low 60s. Onshore flow returns by Saturday afternoon as the area of high pressure continues to move towards the northeast. Over the weekend, a weak upper level trough will attempt to produce rain showers but with moisture lacking (most models indicate PWATs 0.50"-0.75") and jet mechanics not looking favorable, this is not likely. However, the chances of high temperatures bouncing back into the 70s is very likely for both Sunday and Monday. Speaking of Monday, this is where the forecast gets tricky. Models indicate a cold front stalling out over the far northern CWA. Not much instability is expected, but with PWATs just over 1.00", rain showers will be possible mainly along the frontal boundary through Monday night. Some rain showers could extend further south towards the coast as well during the daytime on Monday. Moisture will mainly be relegated to the lower levels of the atmosphere, so as of right now not expecting heavy rain. An upper level trough will help push through the next significant cold front on Wednesday afternoon. This front will have more moisture to work with (PWATs 1.0"-1.5") and also a bit of instability so there will likely be embedded thunderstorms along the frontal boundary. The rain/thunderstorms will not linger for long, and temperatures behind the front as of right now look to drop in the low 40s/upper 30s on Wednesday night across the CWA. 26 MARINE... Light to moderate onshore flow will continue for the rest of the day with waves ranging in the 4-5 feet. Caution flags will continue through this evening for the offshore waters. Scattered showers and isolated thunderstorms will be possible later today as a strong cold front crosses the coastal waters early tonight. Very strong northwesterly winds will develop in the wake of the frontal passage tonight into Thursday. A gale warning is in effect from 6 PM CST this evening through early Thursday afternoon. Winds and seas are expected to gradually decrease Thursday afternoon as high pressure moves overhead. Onshore flow returns this weekend along with the possibility of showers before the next cold front expected sometime late Sunday into Monday. Winds will strengthen early next week, and may require the issuance of SCEC/SCA. Offshore flow could return by midweek. 24 FIRE WEATHER... A strong cold front will move through this afternoon and this evening and will bring scattered showers and isolated thunderstorms to the area. Strong northwesterly winds are expected tonight, but these winds will be weakening by the mid to late morning on Thursday. Cold and considerably drier conditions are expected with relative humidity values on Thursday falling to around 20 percent. Elevated fire weather conditions are possible as a result, particularly if winds are slow to die down. 42 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 35 55 33 63 38 / 0 0 0 0 0 Houston (IAH) 37 54 36 62 41 / 40 0 0 0 0 Galveston (GLS) 41 53 45 60 52 / 100 0 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Wind Advisory until noon CST Thursday for the following zones: Brazoria Islands...Coastal Brazoria...Coastal Galveston... Coastal Jackson...Coastal Matagorda...Galveston Island and Bolivar Peninsula...Matagorda Islands. Wind Advisory until 6 AM CST Thursday for the following zones: Austin...Brazos...Burleson...Chambers...Coastal Harris... Colorado...Fort Bend...Grimes...Houston...Inland Brazoria... Inland Galveston...Inland Harris...Inland Jackson...Inland Matagorda...Madison...Montgomery...Northern Liberty... Polk...San Jacinto...Southern Liberty...Trinity...Walker... Waller...Washington...Wharton. GM...Gale Warning until noon CST Thursday 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...Galveston Bay...Matagorda Bay...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. && $$ Discussion...99 Aviation/Marine...99
Wind Advisory
URGENT - WEATHER MESSAGE National Weather Service Houston/Galveston TX 914 PM CST Wed Dec 23 2020 TXZ176-177-195>199-210>214-226-227-235>238-313-241115- /O.CON.KHGX.WI.Y.0012.000000T0000Z-201224T1200Z/ Madison-Walker-Burleson-Brazos-Washington-Grimes-Montgomery- Colorado-Austin-Waller-Inland Harris-Chambers-Wharton-Fort Bend- Inland Jackson-Inland Matagorda-Inland Brazoria-Inland Galveston- Coastal Harris- Including the cities of Madisonville, Huntsville, Caldwell, Somerville, College Station, Bryan, Brenham, Navasota, Conroe, The Woodlands, Columbus, Eagle Lake, Weimar, Sealy, Bellville, Hempstead, Prairie View, Brookshire, Waller, Houston, Winnie, Mont Belvieu, Anahuac, Stowell, Old River-Winfree, El Campo, Wharton, Missouri City, Mission Bend, Sugar Land, Rosenberg, First Colony, Pecan Grove, Edna, Ganado, Bay City, Pearland, Alvin, Angleton, League City, Friendswood, Pasadena, and Baytown 914 PM CST Wed Dec 23 2020 ...WIND ADVISORY REMAINS IN EFFECT UNTIL 6 AM CST THURSDAY... * WHAT...North winds 20 to 30 mph with gusts to 40 mph. * WHERE...Portions of south central and southeast Texas. * WHEN...Until 6 AM CST Thursday. * IMPACTS...Gusty winds could blow around unsecured objects. Tree limbs could be blown down and a few power outages may result. PRECAUTIONARY/PREPAREDNESS ACTIONS... Use extra caution when driving, especially if operating a high profile vehicle. Secure outdoor objects. && $$
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