498 FXUS64 KHGX 201647 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 1047 AM CST Sun Dec 20 2020 .SHORT TERM [Today Through Monday Afternoon]... Skies clearing out quickly even with the low sun angle this morning. Patchy light fog still present at 10 am but is dissipating quickly with heating/mixing. SC will probably continue into the early afternoon over the eastern CWA then full sun this afternoon. A cool day on tap with highs only climbing into the upper 50s to mid 60s. Overnight clear skies to start off with should allow for quick radiational cooling and probably lead to the development of areas of fog again toward morning. High pressure over TX meanders out into the NW Gulf/LA coast by Monday night which should get a light southerly flow going over SETX Monday. A little warmer Monday and some passing high clouds - CI spreading into the area late in the day. 45 && .AVIATION [18Z TAF Issuance]... Fog dissipating quickly and VFR should then prevail through 05z. Radiation fog setup tonight and expecting fairly widespread MIFG becoming IFR-VLIFR BR/FG. Fog should dissipate Monday morning 14-16z...probably earlier on that time frame across the north and later for southern terminals. 45 && .PREV DISCUSSION /Issued 545 AM CST Sun Dec 20 2020/... .LONG TERM [Tuesday Through Sunday]... Surface high pressure will be located over the mid-south on Tuesday morning with winds becoming onshore. A weak 500 mb short wave will be crossing Texas but moisture remains sparse with PW values still under a half inch. There should be a nice warm up underway and MaxT values should warm into the mid/upper 60's. The onshore flow will strengthen Tuesday night into Wednesday as the high drifts toward NC and a strong short wave moves across the Central Plains. Moisture increases under a a cap in the 850-700 mb layer and the column saturates between 09-12z Wednesday. The extra lift from the trough coupled with persistent WAA should yield some showers by Wednesday morning but more likely by afternoon. The next significant weather feature arrives Wednesday night in the form of a cold front that will race across the plains Weds aftn and reach the upper Texas Coast Weds night. Still some timing differences as the ECMWF and Canadian have slowed the front bringing it through Thurs AM. It's a strong front with significant pressure rises behind it so feel this feature will move quickly across the state. Ensemble data also seems to support this so will lean toward the faster GFS for timing. The front will trigger some showers along and just behind it as it moves through Winds will become NW Wed night and Thursday and increase significantly. A Wind Advisory may be needed over parts of the area Wed night into Thu. The strong NW winds will like push water out of the bays and another Low Water Advisory will likely be required. 850 mb temperatures fall to -2.0 at KCLL and 0.0 C at Houston so MaxT values on Thursday will struggle to reach 50 degrees. Another concern for Thursday is fire weather. Dry air will filter (dew pts in the teens) into the region with RH values currently progged to fall to around 25 percent. NW winds will be strong, near 20 mph and the combination of low RH and gusty winds will create dangerous fire weather condition. It'll be Christmas Eve with fireworks and holiday get-togethers with grills and outdoor fires. It'd be wise to use extreme caution if burning outside on Thursday. Winds should decouple Thursday night but it will remain dry and cold. Am expecting very efficient cooling Thursday as ideal radiational cooling conditions will exist. Leaned strongly toward the ADJMex data for MinT as it seems to be handling cold spots far better than any blends. Will likely see temps fall into the 20's over the NE zones toward Conroe. 850 temps begin to warm Friday and the warming will persist into Saturday. A slow moderation in MaxT values is expected with temperatures warming into the upper 50's Fri, low 60's Saturday and upper 60's by next Sunday. Cirrus clouds will prevalent on Friday with mostly cloudy skies on Sat/Sun as low moisture makes a return with onshore winds. 43 .MARINE... Winds and seas have been lowering through the night after rising in the wake of yesterday's cold front. Wave heights of 4 to 6ft are still possible in the offshore waters through the morning, so small craft should still exercise caution out there. Some dense fog was seem on webcams in the upper reaches of the Ship Channel along with some patchy fog across Galveston Bay this morning. This fog should dissipate by the midmorning hours with the rising sun. There is potential for some fog to redevelop tonight into Monday morning in the Ship Channel and in Galveston Bay. High pressure will be moving over the are through midweek providing the area with mostly clear skies and light winds. A disturbance will move through the area late Wednesday bringing a chance of showers. Strong offshore winds will be possible after the frontal passage approaching Gale force overnight Wednesday into Thursday. The strong offshore winds will also bring the possibility of the need for Low Water Advisories in the Bays on Thursday. JPF && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 62 39 68 42 68 / 0 0 0 0 0 Houston (IAH) 64 43 67 44 68 / 0 0 0 0 0 Galveston (GLS) 62 51 64 55 67 / 0 0 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM/AVIATION/MARINE...45 LONG TERM/FIRE...Cady