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
223 FXUS64 KHGX 052126 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 326 PM CST Fri Feb 5 2021 .SHORT TERM [Today Through Saturday Night]... As the rain begin to fill in this morning, we received a few reports of sleet from the College Station area. This was the result of saturation from -20 to 0 degrees Celsius in the mid-levels on top of a dry layer below it. As the precipitation fell, it was able to drive wet bulb temperatures aloft down to below freezing. As a result, we saw a little bit of sleet mixed in with the rain up north. Just a day after near record breaking maximum temperatures, we`re talking about sleet reports...gotta love weather in Texas! Although instability is low, some rumbles of thunder are being heard within some of the heavier rain showers. The good thing about the rain is that it`s keeping temperatures down into the 50s today, which means it feels much more February-like than yesterday. The heavier rain showers will continue their southerly trek, but there will still be a lingering possibility for scattered rain showers in our northern counties going into the evening hours. The rain showers will taper off for the entire region around midnight. In the early morning hours tomorrow, a surface inversion will develop and trap the moisture close to the surface. As a result, patchy fog is likely for the central and southern portions of the CWA. Not expecting temperatures to drop that much in the overnight hours. Lows will be in the mid-to-upper 40s. Temperatures for Saturday will be a bit warmer with highs in the low 70s. Fortunately, an area of low pressure will skirt to east across north Texas and will drag a cold front through the area on Saturday in the late afternoon/evening hours. This front will also push the low clouds out of the area making way for clear skies going into Saturday evening. Radiational cooling plus CAA through the post- frontal northwesterly winds means we`re in for a cold one on Saturday night. Low temperatures will range from the mid 30s up north, low 40s in the central/southern CWA, and mid-to-upper 40s along the coast. Batiste && .LONG TERM [Sunday Through Friday]... The long term period will start out gorgeous as high pressure slides across Texas following Saturday`s cold front. Mostly clear skies, light winds, and highs in the mid to upper 60s are on tap for Sunday, but the high pressure providing us with this pleasant weather doesn`t stick around long. It will quickly exit to the east and weaken as an upper level trough swings across Texas on Monday. With the high pressure to the east of us, southeasterly flow and higher moisture returns on Monday warming temperatures back into the low 70s on Monday, and then in the mid to upper 70s by Tuesday. PWATs climb to over 1 inch by Tuesday, which combined with some daytime heating, should lead to some isolated showers. A weak cold front is expected to move through the area late Tuesday ushering in cooler temperatures Tuesday night into Wednesday that will persist through the rest of the week. An elongated boundary that spreads across the entire Gulf Coast will stall out Wednesday through Friday. There is quite a bit of disagreement in the guidance on the position of this boundary, and of the system that will eventually help move it out. All the global guidance has a surface high pressure building in across the Central Plains by Wednesday, but the strength and location of this high pressure differs. The GFS solution has a weaker and further north high pressure (centered over Iowa), allowing the stalled boundary to be positioned a bit further north. This brings scattered showers along the coast starting Wednesday afternoon through Thursday. The EC has a stronger high pressure located further south over Missouri, which pushes the boundary further south keeping most of the precipitation just offshore on Wednesday. The Canadian has the strongest high pressure of the bunch, pushing the stalled boundary all the way into the Central Gulf by Wednesday night. The strength of the high pressure to north on Wednesday will not only determine the PoPs, but also how cool we get on Wednesday. High temperatures Wednesday afternoon currently range from the mid 40s with the stronger high pressure solution (Canadian), to the upper 50s for the further north/weaker high pressure (GFS). Model differences continue to differ through the end of the long term period. An upper level trough will be moving into Southern California on Wednesday, but how strong and how quickly it moves west will determine how the end of the long term period pans out. The GFS is the weakest and quickest solution bringing the trough across Texas late Thursday into Friday increasing PoPs Thursday afternoon into Thursday night, but then drying out through the weekend. The EC has had the upper level trough stronger, becoming a closed low over the Baja Peninsula by Thursday evening. This solution brings precipitation beginning Thursday, but continues it into the weekend as the stalled boundary stays parked near the area. The Canadian is a bit in the middle of the road between the GFS and EC, with a stronger trough moving across Texas on Friday. The real forecast challenge Thursday night will be how cold it gets. Temperatures will be flirting with near freezing across the northern tier of counties bringing the potential for a wintry mixture to those areas. There are still a lot of uncertainties in this forecast, so temperatures may trend warmer or cooler through the next few days. Fowler && .AVIATION [18Z TAF Issuance]... Rain showers moving through the area are bringing temporary MVFR conditions underneath the heavier showers. In the northern line of showers, some lightning is occuring as well. Winds remain northeasterly/easterly around 5-10 knots with VFR conditions prevailing for locations either outside of the rain or underneath lighter rain showers. Going into the evening hours, winds will continue to be easterly and also decrease in magnitude. Cloud ceilings will lower to MVFR after sunset. In the early morning hours for Saturday, patchy fog is likely across the area so have included IFR/LIFR ceilings for all sites except CLL. Expecting these conditions to persist until northwesterly winds around 10 knots kick in right around 18z. The IAH TAF displays this trend of ceilings returning to VFR going into Saturday afternoon following FROPA. Batiste && .MARINE... Gusty northeasterly winds around 20-25 knots gusting to 25-30 knots continue for Galveston Bay and the nearshore waters so the SCA has been extended to 3pm. The SCA for the offshore waters continues through 9pm. Winds will gradually decrease throughout the day from north to south as the pressure gradient weakens. Offshore seas will build up to 7 feet going into tonight before beginning to decrease. Overnight tonight, winds will become more easterly ahead of the next cold front which will pass through on Saturday afternoon. Following this offshore winds will prevail through Sunday. As high pressure moves off to the east, onshore flow will return late Sunday/early Monday and persist until the next cold front on Wednesday. This front will bring a northeasterly wind that will persist through Friday. Resultingly, the seas will gradually build up going into Friday as well with 5-6 ft seas nearshore and 7-9 ft seas offshore. Batiste && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 44 70 37 66 46 / 10 0 0 0 0 Houston (IAH) 46 68 41 63 48 / 20 0 0 0 0 Galveston (GLS) 51 67 49 60 55 / 30 0 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Small Craft Advisory until 9 PM CST this evening for the following zones: Matagorda Islands. GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 9 PM CST this evening for the following zones: Matagorda Bay. Small Craft Advisory until 9 PM CST this evening 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...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. Small Craft Advisory until 6 PM CST this evening for the following zones: Galveston Bay. SMALL CRAFT SHOULD EXERCISE CAUTION until 9 PM CST this evening for the following zones: Galveston Bay. && $$
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