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
764 FXUS64 KHGX 062343 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 643 PM CDT Tue Apr 6 2021 .AVIATION [00Z TAF Issuance]... With southerly winds continuing to supply moisture to SE TX and forecast soundings indicating strong saturation at low-levels, another night of MVFR to potentially IFR cigs is in store across the area. Have maintained trends from the previous package depicting the development of a BKN to OVC deck of around 1-1.5 kft by around 03 to 06Z. Have also included FEW decks at IFR levels to account for a potentially more pessimistic scenario. While winds should relax slightly overnight from today`s gusty conditions, speeds should still remain around 10 knots and most fog development should be inhibited. Our next shot at precipitation comes tomorrow as a surface cold frontal boundary approaches the area tomorrow afternoon, with scattered thunderstorms expected to develop along and ahead of the front. With forecast soundings indicating stronger capping south of the I-10 corridor and hi-res models confining development across the northern half of the area, have opted to included VCTS wording at IAH and sites north. Winds will remain elevated tomorrow, reaching around 15 knots with gusts to around 25 knots. Cady && .PREV DISCUSSION... /ISSUED 330 PM CDT Tue Apr 6 2021/ SHORT TERM [Tonight Through Wednesday Night]... Mainly partly cloudy skies prevail across Southeast Texas this afternoon along with gusty south to southeast winds and spotty showers. This flow has helped to warm temperatures up into the upper 70s to lower 80s across the area, and we might see a mid 80 high or two before the afternoon comes to an end. A partly to mostly cloudy pattern early in the evening should become a mostly cloudy to cloudy scenario overnight under a continuing onshore flow (gusty at times). A shower or two cannot be ruled out overnight and tomorrow morning (look for lows to be in the upper 60s to lower 70s), but an increase in rain chances will occur late tomorrow morning through tomorrow afternoon and on into early tomorrow evening as a storm system and its showers and thunderstorms develop/moves to the east & southeast across the area. There will be a risk of strong to severe storms with this system, especially to the north through northeast of the Houston area where the Storm Prediction Center continues show- ing a slight to marginal risk on their Day 2 Outlook and where the greater instability is expected to develop. Further to the south of the risk area will be locations that will need to deal with some capping that if holds will keep the stronger activity in SPC`s risk locations. Enjoy Wednesday`s highs that should top out in the low/mid 80s because even warmer readings are coming on Thursday & Friday (see Long Term section below). 42 LONG TERM [Thursday Through Tuesday]... Have you been longing for summer-like heat? If so, then you`re going to love the temperatures for Thursday and Friday! If not, then you may want to skip to the next paragraph. Models are in agreement on 850mb temperatures around 18-19 degrees Celsius which supports surface temperatures in the upper 80s. With skies remaining partly cloudy, there won`t be much to prevent us from reaching these temperatures. 850mb temperatures increase a bit going into Friday, which would increase the highs... However, increasing clouds ahead of a developing area of low pressure should limit the amount of daytime heating, so went with the upper 80s again for Friday`s high temperatures. Speaking of Friday, this is when we`re expecting our next round of showers/thunderstorms. An upper-level low in the Central Plains will drag in a cold front into North TX on Friday morning. Model consensus still remains on surface low pressure developing on the tail end of this front near the TX panhandle. As this low traverses to the east across our CWA, it will encounter a favorable environment for strong to possibly severe thunderstorms. Through the persistent onshore flow, PW values will range from 1.2"-1.4" so there will be plenty of moisture to work with. A jet streak entering the CWA from the west will place the region close to the left exit region favoring upper-level divergence, which will be the source of lift. Depending on which model you look at, CAPE values will be substantially high with values around 3000 J/kg. There will be a capping inversion in place around 850 mb, but with highs in the upper 80s expected there is a good chance of the cap breaking. Speed shear looks to be favorable as well with a few models hinting at a LLJ developing over the CWA (the exact placement and extent is still up in the air). The ingredients are all there, the lingering question is can we break the cap. I`ve leaned towards yes! As the low pushes out to the east, a weak cold front will move through the area Saturday morning and briefly changeover the winds to northeasterly and clear out the cloud cover. Surface high pressure moves off to the east by Monday placing the region back into onshore flow, which will also increase clouds cover. The good news is that high temperatures for Saturday will be slightly cooler with highs in the upper 70s/low 80s, but we`re right back into the upper 80s for Sunday and Monday. There is another cold front on the horizon for Monday night/Tuesday morning, but there is still a bit of uncertainty with how far south it will go and how quickly we dry out following FROPA. Due to the uncertainty, leaned towards NBM for PoPs on Monday/Tuesday with thunderstorms possible along the frontal boundary. Batiste... MARINE... A tightened pressure gradient between high pressure off to the east and low pressure off to the west and northwest will bring an increase in winds and waves across the area tonight. Needed to extend the Caution flags for the bays & nearshore waters to cover tonight and upgraded the caution flags to advisory flags for the offshore waters also for tonight. A weakening gradient will occur tomorrow, and this should result in a gradual trend downward in both winds and seas. Shower development could show up tonight through early tomorrow afternoon, but an increasing chance trend could end up materializing some time from late in the afternoon through early in the evening on Wednesday as the next cold front approaches the area. Mainly moderate winds and slightly elevated seas are expected for the rest of the week & on into the weekend. 42 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 82 68 84 56 88 / 20 0 40 0 0 Houston (IAH) 81 69 83 63 88 / 20 0 40 20 0 Galveston (GLS) 75 69 77 67 76 / 10 0 20 20 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...Small Craft Advisory until 7 AM 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. && $$ Discussion...99 Aviation/Marine...99
No comments:
Post a Comment