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
155 FXUS64 KHGX 090252 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 852 PM CST Mon Feb 8 2021 .DISCUSSION... Low ceilings are in the process of developing and once winds decouple, the ceilings should lower to the ground and widespread fog is expected. Will wait a bit for signs of this to occur and will likely have a Dense Fog Advisory out by 06z or shortly thereafter. Made some other changes in the short term, mainly for Tuesday. A cold front over North Texas will slide south tonight into Tuesday. The 00z NAM and the CAMs all bring the front down to the US 59 corridor. MaxT values are going to be much cooler over the north tomorrow and have some concern the even MaxT values for Houston might be a little warm. Looking up stream, temperatures at 9 PM are 10 to 20 degrees cooler than it is currently at KCLL and temps are in the 30s in North Texas. Pressure rises look strong enough to push the front into the CWA. Have lowered MaxT values and brought a wind shift into the CWA for Tuesday. 43 && .PREV DISCUSSION... /ISSUED 639 PM CST Mon Feb 8 2021/ AVIATION... Conditions will deteriorate overnight as low level moisture increases beneath strong capping. With clear skies and light winds over the northern half of the region, conditions look favorable for radiation fog and near the coast, warmer air overriding cooler shelf waters will produce periods of sea fog. Would expect fog to develop near the coast between 03-06z and for inland fog between 07-10z. A mix of IFR/LIFR expected areawide for the morning push at area airports. Gradual improvement is expected around 16z with modest improvement to a mix of VFR/MVFR by afternoon. The exception is KGLS, as fog could linger for much of Tuesday. 43 PREV DISCUSSION... /ISSUED 350 PM CST Mon Feb 8 2021/ SHORT TERM [Through Wednesday Night]... Developing low near Abilene and an associated front along Northern TX and Gulf Coast states. Southeasterly flow persists along the coastal area of SETX and LA until a cold front later in the week. The low and associated front will move southeast a bit, but will stall right along the northern counties. Until then, the potential for fog development will be on the rise. Moisture ridge over the CWA developing over the area and amplifies tonight. Southerly flow will help bring the warmer air over the area along with some extra moisture. With that, fog development is looking promising. Coastal counties will most likely see dense fog, but even our northern counties will see fog late tonight, and early tomorrow morning. Tomorrow, most of the fog should dissipate but the coastal counties could have some lingering a bit as sea fog still remains. Low stratus will persist most of the day with maybe some short breaks, but not looking like an SPF50 day overall. Tomorrow night, the fog will redevelop as the sunsets and the temperatures cool and we get to saturation again. With the overall pattern in the area the same, dense fog is still a possibility. Depending on how much of the previous nights fog dissipates, or how much remains in the coastal waters, onset could be soon for tomorrow night. 35 LONG TERM [Wednesday through Monday]... Rain chances will be increasing on Weds...with the best POPs across our N/NE CWA. The combination of a stalled cold front (likely close to our northern borders) and a developing low/mid level jet as well abundant daytime heating/low-level moisture (PWs from 1.2" to 1.4") should support the development of scattered showers/isolated thund- erstorms by Weds afternoon. As all/most of these features remain in place, elevated POPs will likely persist into Weds night and Thurs. However, the main WX story for Thurs will be the arrival/passage of the strong cold front and the cold arctic air mass filtering down in to the region in its wake. Did keep the mention of isolated TSRA in for FROPA with most of this activity likely elevated. Rains will be ending with the front from west to east by late Thurs afternoon/eve and continuing through Thurs night. As it has been hinted at previously, the main forecast issues going forward will be related to the very cold air mass that`s progged to settle over the region by the end of the week and into the weekend. Low temperatures Fri morning should range from the mid to upper 30s inland to the mid to upper 40s along the coast. Strong surface high pressure building into the state from the north and persistent cold air advection will help to keep high temperatures in the 40s/50s on Fri. Temperatures could fall even lower for Sat/Sun by another 5 to 10 degrees for both highs and lows. As such, we could be looking at a few nights of prolonged freezing or below freezing temperatures. In addition to these colder temperatures, shortwaves moving across the area from the SW will have the potential produce some low POPs Sat/Sun/Mon. And yes, while there are hints that we could see some frozen/wintry precipitation (per GFS extended runs), confidence not high enough to include its mention in the grids at this time. 41 MARINE... Light to moderate onshore winds have returned, while temperatures and dewpoints are increasing to near and above water temperatures across the coastal waters. This will create an environment favorable for sea fog development, and this is expected to persist until a cold front arrives early Thursday. At times, some of this fog may become dense. Moderate to strong offshore winds are expected to develop in the wake of this front, increasing seas - particularly those closer to 60 nm offshore. Caution flags look likely at the least, and a small craft advisory is a probable scenario. PREV DISCUSSION /Issued 1142 AM CST Mon Feb 8 2021/... AVIATION [18Z TAF Issuance]... VFR conditions today with some MVFR ceilings around 030 for most TAF site. Tonight, MVFR will turn to IFR, which then turns to LIFR. Foggy conditions tonight as a ridge of moisture sets up over the TAF sites and light southerly flow brings in warm moist air. This set up looks to remain until frontal passage Thursday morning, but fog during the day should mix out. Low stratus during the daylight hours will still keep most terminals at or below MVFR, before fog returns tomorrow night. 35 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 56 71 57 72 49 / 0 0 0 50 50 Houston (IAH) 59 75 61 77 60 / 0 10 0 40 40 Galveston (GLS) 61 68 62 69 62 / 10 10 0 20 40 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ Discussion...99
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