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 172339 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 539 PM CST Sun Jan 17 2021 .AVIATION... Light and variable winds overnight with a few high clouds. Strengthening SE to S winds during the day tomorrow (maybe becoming gusty too) along with gradually increasing clouds generally around 3000-5000 feet. Anticipating a BKN/OVC deck around 5000 feet to develop late in the afternoon or early tomorrow evening, and winds should be coming down some in the evening. 42 && .PREV DISCUSSION... /ISSUED 329 PM CST Sun Jan 17 2021/ SHORT TERM [Today through Tuesday Afternoon]... Cloud cover briefly returned to the area as a weak shortwave passed through the area this morning. A quiet weather day is expected across Southeast Texas as high pressure remains overhead. Mid-level flow is still northwesterly, so we`re still seeing the advection of dry air (and a bit of dust) as dew points this afternoon have fallen into the mid 20s. This creates a bit of concern for fire weather as RH values are down into the 20-30% range. Surface winds will remain around 5-8 knots and transition to light and variable by the late afternoon. Afternoon high temperatures for today will be in the mid- to-upper 60s thanks to the plentiful dry air. Temperatures will be a bit warmer beginning tonight as the area of high pressure pushes off to the east and introduces a southeasterly flow into the CWA. Most of us will be waving goodbye to lows in the 30s as the southeasterly wind will only allow temperatures to drop into the low 40s. Our northern counties will still drop into the upper 30s. For our cold weather fans, this will be the last cold night for the rest of the work week. By tomorrow, high temperatures will breach the 70 degree mark for most locations and low temperatures will be in the mid-to- upper 50s courtesy of some good ol` WAA as southeasterly winds continue to strengthen. The upward trend of temperatures continues into Tuesday with highs topping out in the mid 70s. The southeasterly flow is an integral part of the forecast for this upcoming week because it will provide more than just WAA. Theta-E (instability) and PWATs will gradually increase across Southeast Texas beginning on Monday afternoon. This is important because a cold front is expected to stall over our northwestern counties on Tuesday morning which will create an area of convergence. At this point, PWATs will be around an inch across most of Southeast Texas. Rain chances will be highest across the northwestern portion of the CWA for Tuesday thanks to the lift provided by the frontal boundary. Relatively dry mid-levels and a subsidence inversion around 700 mb left over from the departing area of high pressure indicates that heavy rain is not likely, at least through Tuesday afternoon. Moisture will continue to increase going into midweek as the southeasterly winds persist and will eventually mix out this inversion and moisten up the mid-levels. 26 LONG TERM [Tuesday Night Through Sunday]... Shallow, stalled frontal boundary will linger about northern parts of the CWA into Wed then eventually washout Wed night & Thurs. This boundary, along with embedded disturbances riding in the swly flow aloft will provide continued chances of precip in that general vicinity. Further south, lack of a focusing/forcing mechanism and mid level ridging nosing into the area from the Gulf will be limiting factors for precip. But they won`t be left out of the dreariness - persistent llvl warm/moist onshore winds moving over cooler shelf waters should produce cldy conditions and a somewhat favorable set-up for sea fog into the weekend. Next upper trof digs down the west coast this weekend, but medium range solns are not on the same page in regards to when it`ll start making some ewd progression. This leads to considerable fcst uncertainty Sat- Tue, but figure we`ll see at least some iso/sct precip around until we get its associated frontal boundary thru the region which appears beyond the scope of this fcst package. 47 MARINE... Light northerly winds and smooth seas persist as high pressure remains overhead. This area of high pressure will begin to push off to the east overnight, which will introduce an onshore southeasterly flow that will gradually strengthen. Wind speeds will approach SCA criteria on Monday night/early Tuesday morning. The onshore flow will persist through most of the week seas will build up to 4-7 feet by Tuesday. Moisture will be on the rise as well which will bring about the threat of sea fog from Tuesday night and into the weekend for the coastal areas and nearshore waters. A cold front will approach the coast late on Friday, but forecast models indicate that it will not push all the way through. Wind flow transitions to southerly by the start of the weekend. 26 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 39 69 56 72 52 / 0 0 20 40 50 Houston (IAH) 41 68 57 72 55 / 0 0 10 10 10 Galveston (GLS) 51 64 59 66 58 / 0 0 0 10 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$
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