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 190530 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 1130 PM CST Mon Jan 18 2021 .AVIATION... Overnight, expecting lower ceilings inland (MVFR to possibly IFR) and higher ceilings near the coast (possibly staying VFR). Could see some -RA/-SHRA development overnight inland, so have VCSH at those TAF sites. Similar pattern during the day tomorrow with lower ceilings along with possible rains inland and higher ceilings and less rain near the coast. Forecast gets increasingly complicated tomorrow evening into tomorrow night as slow moving cold front enters northern sites resulting in lowering ceilings and probably better -RA/-SHRA coverage. Might also end up dealing with fog development near/along the coast and Bay areas too. 42 && PREV DISCUSSION... /ISSUED 332 PM CST Mon Jan 18 2021/ SHORT TERM [Through Tuesday Night]... Well say goodbye to those mostly clear skies Southeast Texas has been enjoying the past couple of days. The high pressure that was providing us with those beautiful (but chilly) conditions has slid to the east today ushering in southerly flow into the region. Cloud coverage has gradually increased through the early afternoon from west to east as the southerly flow influxes higher moisture into the region. Dew points are about 20 degrees higher as of writing this discussion (around 3pm) than this time yesterday, and will only continue to climb as the southerly fetch continues. There has been some very light returns on the radar popping up recently across the southwesterly zones, so have increased PoPs slightly for this area this evening. Isolated to scattered showers will also be possible overnight tonight across most of the area. The increased moisture will also create the possibility of some patchy fog developing tonight. The area of focus for showers will then shift to mainly the northern third of the region tomorrow morning as a weak cold front approaches the area and stalls - which brings us to the biggest question of the short term. The stalling of the cold front is still expected, but there has been some changes on exactly where it will stall in the guidance. The past few days, guidance has had the front stalling north of the area with Burleson to Houston counties having the highest chances of precipitation. The global models still support this solution, but some of the CAM guidance has been bringing the front much further south than previously shown. The NMM brings the front down to near Huntsville Tuesday afternoon, and the ARW has it even further south towards the Houston Metro area. However, the HRRR and TT-WRF favor the further north solution. I am gonna favor these more northern solutions due to the lack of forcing behind the front that would make it go further south. However, with the uncertainty in the frontal progression, I did increase PoPs a bit further south than the previous package. PWATs will be climbing to around 1 inch tomorrow afternoon, so the showers the do form will have a chance to produce some locally moderate rainfall. Generally expecting around a quarter to half an inch of rain across the northern third of the area. The southerly flow has not only increased the moisture into the area, but also the temperatures. Low temperatures tonight and tomorrow night are expected to drop into the upper 50s to low 60s, which is around 20 to even 30 degrees warmer than last night`s lows! Fowler LONG TERM [Wednesday Through Monday]... Looking like a cloudy, warm & somewhat damp time period overall. A weak, nearly stationary frontal boundary that should be draped across parts of the area will be in the process of washing out Wed & Wed night. Deeper llvl moisture will remain in place and with some passing disturbances in the swly flow aloft, will maintain iso/sct POPs across the northern half of the area thru the work week. Closer to the coast...anticipate some periods of sea fog. Best overall precip chances and amounts will likely occur Friday into Fri evening with the aid of a backdoor cool front that should be sagging thru the area. After a very brief period of northeast winds behind it, expect onshore winds to resume Saturday night and Sunday bringing deeper moisture and rain chances back into the region as the next system develops to our west. 47 MARINE... Hoisted the SCA flags in the 20-60nm waters through tonight for increasing southeast winds and building seas. Both should begin diminishing off Tuesday as a weak frontal boundary sags into north central Texas. Warmer air moving over the colder shelf waters and bays will lead to periods of sea fog this week. Though some patchy fog could be observed as early as Tuesday morning, slightly better chances should occur in the Wednesday through Friday timeframe. A cool front is expected to move into the waters from the northeast on Saturday, but onshore winds should quickly resume and increase Saturday night and Sunday. 47 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 59 65 49 62 58 / 50 70 50 30 30 Houston (IAH) 59 72 54 69 58 / 30 30 30 20 20 Galveston (GLS) 60 63 56 65 60 / 10 10 10 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...Small Craft Advisory until 6 AM CST Tuesday for the following zones: 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. && $$
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