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 122331 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 531 PM CST Fri Feb 12 2021 .AVIATION [00Z TAF Issuance]... Except for the northeastern corner of the area (including UTS and CXO), most of the area has clawed its way just beyond IFR into low MVFR conditions. From here, the model guidance is split on how quickly improvement will come - given obs, have sided with the more pessimistic view and kept things just above IFR until tomorrow afternoon. Have hinted at arrival of showers at the very end of the period for CLL and in the IAH extended. && .PREV DISCUSSION /Issued 352 PM CST Fri Feb 12 2021/... .SHORT TERM [Tonight Through Saturday Afternoon]... Tonight will be cold and cloudy with northerly winds 10 to 15 mph and temperatures holding in the 30s inland and near 40 on the coast. Some very light drizzle is possible this evening. A s/w approaches from the southwest Saturday and rain chances increase from the southwest to northeast throughout morning-afternoon hours. Some of the far northwestern areas could see some patchy light freezing drizzle toward sunrise into the afternoon. Temperatures should reach the 32-34 degree range for a few hours near College Station Saturday afternoon ending the freezing drizzle threat. 45 .LONG TERM [Saturday Night Through Friday]... *** OVERVIEW *** * As frigid arctic air pushes into SE Texas, 3 storm systems are expected to bring periods of winter weather to the region over the next 5-7 days which will have the potential to pose a significant threat to life and property. * The arrival of the first system will bring periods of sleet and freezing rain on Saturday night/early Sunday with the greatest impacts north of the I-10 corridor. * A second, stronger disturbance combined with much below- freezing temperatures will bring sleet, snow, and freezing rain to all of SE Texas, causing significant disruptions to travel and potential power outages. Near record cold temperatures will develop as this system departs by Monday night. * A third round of sleet and freezing rain is possible Wednesday into Thursday, though uncertainty surrounding this system remains higher. We continue to expect a significant and potentially historic period of prolonged subfreezing temperatures with several rounds of winter precipitation to impact SE Texas over the next week. As a persistent deep area of surface high pressure remains the dominant synoptic feature over the central third of the CONUS, moderate to strong northerlies will continue to enhance CAA, with temperatures remaining on a downward trend over the next several days. By late Saturday, most locations will be at or near freezing with the northern third of the area likely to see the 20s. The first of three upper shortwaves will traverse the area late Saturday. Forecast soundings continue to be indicative of sleet/freezing rain north of the Houston metro with a well- saturated column and fairly deep elevated warm layer. Surface /near-surface temps across and south of the metro area will be less favorable for frozen precipitation, but travelers should still remain highly vigilant of road conditions before heading out. Behind the departure of this system, temperatures warm back above freezing on Sunday afternoon but will remain well below normal for mid-February (high 30s-mid 40s). The main period of concern continues to be Sunday night through Monday afternoon. As a second amplifying trough digs into central TX, an associated coastal low will develop at the surface and push into the central Gulf by late Sunday. Ample moisture associated with this feature combined with subfreezing ambient conditions will prove favorable for periods of snow, sleet, and freezing rain to impact all of SE Texas. The most concerning period continues to be the morning hours of Monday, where model soundings within Houston metro show a highly favorable profile for freezing rain. In general, precipitation should begin as mainly rain late on Sunday, transitioning to sleet/freezing rain overnight and finally becoming a mix of snow, sleet, and/or freezing rain during the day on Monday. Snowfall accumulations will reach around 1-3", mainly to the north of the Houston metro. Ice accumulations of 0.10 to 0.25" are possible across the metro northward with lower amounts southward. This complex period of winter weather will create extremely hazardous roadway conditions, particularly on Monday morning. Non- essential travel should unequivocally be avoided during this time. Snow accumulation and significant icing will cause widespread impacts to road networks. Plan to remain where you are on Sunday night for at least all of Monday. As the second system departs and clearing occurs, we`ll enter what will likely be the coldest night across SE Texas in approximately 30 years. Lows will dip into the single digits at most locations north of I-10, with locations to the south reaching the 10s to lower 20s along the coast. Temperature records are likely to fall. All residents of SE Texas should begin to take steps to protect the 4 Ps - people, plants, pets, and pipes. Due to the combined strain of increased energy demands due to cold temperatures and previous winter precipitation, there is also a distinct chance of power outages during this time. We continue to monitor the development of a third system which may bring additional freezing rain/sleet to the area on Wednesday and Thursday. Given the timeframe and differences in model solutions, there continues to be uncertainty surrounding this event. However, there remains the potential for additional disruption due to winter precipitation to occur through mid-week. Now is the time to prepare for this period of hazardous weather. Be sure to have multiple ways to receive weather information and continue to monitor the forecast. Cady .MARINE... Persistent north and northeast winds will continue tonight through Sunday morning. Winds of 15 to 25 knots will prevail during this period with SCEC to SCA conditions. A low begins to form Sunday along the Lower Coast and then shifts east-northeast and will increase the winds in advance of the arrival of the Arctic cold front. The big event appears to be with the Arctic cold front late Sunday night-early Monday. Gale to possibly even storm force winds crank up in the wake of the cold front. Sustained winds of 25 to 35 knots with gusts of 40 to 55 knots will be possible! Seas build to 11-15 feet well offshore. This record setting cold airmass will plunge temperatures and combined with the winds drive down the tide levels and could even help to produce freezing spray as well as freezing rain/snow/sleet in the bays/ICW/immediate nearshore waters. Winds should begin to relax slightly Tuesday morning. Another storm system is arriving late Wednesday with another shot of near gale to gale conditions. && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 29 36 29 37 15 / 20 40 40 20 70 Houston (IAH) 34 40 33 43 23 / 10 30 40 20 60 Galveston (GLS) 38 44 38 46 31 / 10 30 40 20 60 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Winter Storm Watch from Sunday afternoon through Monday afternoon for the following zones: Austin...Brazoria Islands...Brazos...Burleson...Chambers...Coastal Brazoria...Coastal Galveston...Coastal Harris...Coastal Jackson...Coastal Matagorda...Colorado...Fort Bend...Galveston Island and Bolivar Peninsula...Grimes...Houston...Inland Brazoria...Inland Galveston...Inland Harris...Inland Jackson...Inland Matagorda...Madison...Matagorda Islands...Montgomery...Northern Liberty...Polk...San Jacinto...Southern Liberty...Trinity...Walker...Waller...Washington...Wharton. GM...Small Craft Advisory until 6 PM CST Saturday 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. && $$ SHORT TERM...45 LONG TERM...Cady AVIATION...Luchs MARINE...45
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