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 272353 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 653 PM CDT Tue Apr 27 2021 .AVIATION [00Z TAF Issuance]... A mix of VFR to MVFR ceilings with some light showers are expected this evening. Much of these showers are not reaching the ground; therefore, have only added -RA/VCSH at KCLL. BKN to OVC MVFR to occasional IFR conditions return overnight into early Wednesday with patchy fog possible along the coastal terminals. Conditions will gradually improve through the day; before dropping back to MVFR by early Wednesday evening ahead of the next system. Southeast winds will prevail through the period, becoming gusty by late Wed morning. KCLL terminal could see periods of LLWS of 30-40kts at around 1 kft at times tonight. Given low confidence in occurrence, have only kept gusty winds around 20-25 knots through the period. 05 && .PREV DISCUSSION /Issued 322 PM CDT Tue Apr 27 2021/... .SHORT TERM [Tonight Through Wednesday]... Mostly cloudy to overcast skies have relegated temperatures so far this afternoon to the upper 70s/low 80s. Still think that most locations will get just above 80 degrees by the late afternoon. Hi- res model guidance indicates showers/storms developing to our west in the afternoon and moving into our northern counties (generally north of and including Montgomery County). These areas have the best opportunity for the cap to erode with increasing low-level moisture and daytime heating. However, some of these models are overdoing the temperatures. For instance, the NAM and HRW-NMMB indicate 2pm temperatures in the mid 80s while we remain in the upper 70s/low 80s. PW values will be near 2" and CAPE ranging from 1000-1500 J/kg so it`s not a question of if there`s enough moisture or instability, just a matter of if we can warm enough to break the cap. As long as the clouds persist, the cap will remain a difficult task to break. Went with 20-30% PoPs for northern areas to cover the scenario that the cap does break. Regardless, not expecting any significant thunderstorm activity in the area. Moderate southeasterly flow will persist overnight and with clouds remaining in place, tonight`s temperatures will be nearly 10 degrees above normal with lows in the low 70s. There will be another slight chance of showers/storms for our far northern counties on early Wednesday morning. Wednesday presents another challenge with temperatures. Upper-level ridging remains in place, so it`ll definitely be another warm afternoon. The main question lies in how far south will the clouds scatter out. There is pretty good agreement that our northern counties will have sufficient cloud scattering. With 850mb temperatures ranging from 17-19 degrees Celsius, this supports high temperatures in the upper 80s. Further to the south, thinking that cloud cover remains prevalent enough to relegate high temperatures to the mid 80s. Winds will be a bit stronger for Wednesday as well with a LLJ forming over east Texas in association with an area of low pressure developing in north Texas. With steep low-level lapse rates, some moderate to strong gusts will be able to mix down to the surface. Our western and southwestern counties will flirt with the Wind Advisory threshold in the afternoon hours. Batiste .LONG TERM [Wednesday Night Through Tuesday]... Still looking at the potential for periods of showers and thunderstorms beginning Wednesday night across our northern and western areas then spreading eastward across the rest of the area Thursday and Thursday evening in response to a slow mid/upper level low and associated cold front. With models continuing to generally hold on to their differences in the location, strength and eventual eastward progress of the low, have kept some rain in the forecast for parts of the area at the end of the week and over the weekend in case the slower scenarios materialize. For temperatures, generally have highs in the 80s each day except for Friday after the front has moved on through, and have a general/gradual warming trend for the lows beginning toward the end of the weekend and continuing into the start of next week as onshore winds return to the area. 42 .MARINE... A Coastal Flood Advisory has been issued again for much of the Upper TX coast from midnight tonight through 6 PM Wednesday as high tide levels are progged to be near/around 3.5 feet. Otherwise, moderate to occasionally strong south to southeast winds can be expected over the next couple of days likely at caution and advisory levels. The next cold front is still on track to move off the coast and through the coastal waters late Thursday afternoon or Thursday evening. Mainly moderate offshore winds in its wake will transition back to the southeast and south and gradually strengthen over the weekend and into the start of next week as high pressure moves away from the area. 42 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 72 87 69 80 61 / 20 10 50 70 20 Houston (IAH) 72 84 72 84 64 / 10 10 20 60 20 Galveston (GLS) 72 79 72 80 68 / 0 10 10 50 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Coastal Flood Advisory from midnight tonight to 6 PM CDT Wednesday for the following zones: Bolivar Peninsula...Brazoria Islands...Galveston Island...Matagorda Islands. GM...SMALL CRAFT SHOULD EXERCISE CAUTION through Wednesday afternoon 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. Small Craft Advisory until 1 PM CDT Wednesday 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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