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
496 FXUS64 KHGX 012323 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 623 PM CDT Sat May 1 2021 .AVIATION... For the 02/00Z TAFs, areas of rain with embedded showers and thunderstorms can be expected this evening and overnight as the low moves across the state. MVFR and possible IFR conditions will prevail with this activity. After everything moves on through, we could be dealing with some wrap around moisture and clouds (mainly MVFR ceilings) before some clearing sets in. Other issue will be some gusty winds mainly associated with a tightened pressure gradient. 42 && .PREV DISCUSSION... /ISSUED 219 PM CDT Sat May 1 2021/ SHORT TERM [Through Sunday Night]... Upper low situated over Big Bend area with mirrored closed surface circulation to its east. Both are fcst to move ene and toward the area tonight into Sunday morning then exit to the east during the day. Areas of mainly light to moderate rainfall across the region early this afternoon with a lead shortwave passing thru. Limited instability and a worked over airmass has thankfully kept rain rates mostly in check. That said, stronger shra/tstms have developed in the Hill Country into south Tx in advance of the sfc/upper lows and in an area of moderate upper diffluence in association with nose of s-n oriented jet aloft. Rain rates of 2-3"/hr have been observed in some of that convection. This area is fcst to advance ewd toward se Tx late this aftn into the overnight hours. PW`s aoa 2" remain situated near the Matagorda Bay area...the same general area that saw copious amounts of precip this morning. Guidance is mostly a split camp in regards to who sees the highest rainfall amounts in the next 6-12 hours. Some, like TTU WRF are again pinging our sw counties with another 3+ inches, others clip the Brazos Valley with lesser amounts, some in between. At this point, regardless who ends up seeing the "peak" rains, many locations from Matagorda Bay-Katy-Conroe/Huntsville-Lake Livingston have seen 3-7"+ the past several days and it won`t take all that much precip to cause additional flood/flash flood issues **especially if they see some the rain rates occurring to our west**. Think the current FF Watch configuration remains valid and am not planning any changes. Bulk of precip should be exiting the area before sunrise Sunday with any lingering activity ending by late morning once swly flow aloft fills in and atmos begins to dry out. Warm, muggy conditions will prevail for the remainder of the day and Sunday night. 47 LONG TERM [Monday Through Saturday]... To put it simply...Monday is going to be hot. Some locations will see their warmest temperatures of the year thus far by breaking the 90 degree mark. These 5-8 degree above normal temperatures can be attributed to southwesterly flow aloft providing sufficient WAA. With 850mb temperatures ranging from 22-25 degrees Celsius on Monday afternoon and dry air at the surface promoting mixing, high temperatures will be able to reach the upper 80s/low 90s. This will be another sneak peak at summer-like temperatures. A cold front will break up the hot weather party. The GFS and NAM are a bit more progressive with the front when compared to the ECMWF, so I have leaned towards these models for FROPA timing. The front enters our northwestern counties on early Tuesday morning, the Houston metro area by the late morning, and at the coast by Tuesday mid-afternoon. With increasing moisture and instability out ahead of the front (PW values 1.5-2.0" and CAPE values 1500-2500 J/kg), showers and thunderstorms are expected along the frontal boundary. The northern and eastern counties of the CWA have higher PoPs due to more favorable jet dynamics with upper- level divergence in the right entrance region of a jet streak. With PW values peaking around 2", locally heavy rain is possible. This will not be a prolonged rainfall event as the front is expected to push off of the coast without issue. Rain chances do linger off of the coast through Wednesday afternoon, but this is not much of a concern for those on land. After the front passes through, clearing skies, low-to-zero PoPs, and seasonal temperatures are expected for the remainder of the forecast period. High temperatures on Tuesday and Wednesday will only reach the upper 70s/low 80s with highs in the mid 80s back by Thursday/Friday. Overnight temperatures beginning Tuesday night will be on the cool side as well with lows in the upper 50s/low 60s through Thursday night. Temperatures begin to increase a bit towards the end of the work week as high pressure moves off to the east and brings onshore flow and WAA back to the region. Upper and mid-level flow transition from zonal to ridging from mid-week to late-week, so have left PoPs out of the forecast through Saturday. A pleasant period of dry weather awaits us following FROPA on Tuesday. Batiste MARINE... Moderate easterly winds will transition over to southerly and persist through tonight. As showers/thunderstorms move through the coastal waters, some may be accompanied with high wind gusts up to 30-35 knots. Have already seen wind gusts of 35 knots in Matagorda Bay this afternoon. Strong rip currents are expected to continue into Sunday morning. Advisory conditions are expected to persist into early Sunday morning. This is when winds will become southwesterly as low pressure develops in north Texas. Offshore seas will begin to increase with 5-6 foot seas expected by Sunday night. Southerly to southwesterly winds on Sunday night/Monday morning may become moderate with a tightening pressure gradient, but will decrease on Monday afternoon. The next cold front pushes through the coastal waters on Tuesday evening/night. Showers and thunderstorms will be along the frontal boundary with lingering precipitation expected into Wednesday afternoon off of the coast. Moderate northeasterly to easterly winds will prevail in the wake of this front through early Wednesday morning before winds begin to decrease. Offshore flow is expected to prevail through Friday. Batiste HYDROLOGY... Several creeks/rivers are above or near flood stage across the area. Additional rainfall will lead to further rises on area watersheds. 47 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 65 84 71 89 67 / 70 20 10 0 30 Houston (IAH) 68 84 71 90 72 / 70 20 10 0 10 Galveston (GLS) 71 78 74 85 74 / 80 30 10 0 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Flash Flood Watch through Sunday morning for the following zones: Austin...Brazoria Islands...Brazos...Burleson... Coastal Brazoria...Coastal Jackson...Coastal Matagorda... Colorado...Fort Bend...Grimes...Houston...Inland Brazoria... Inland Harris...Inland Jackson...Inland Matagorda... Madison...Matagorda Islands...Montgomery...Northern Liberty...Polk...San Jacinto...Trinity...Walker...Waller... Washington...Wharton. High Rip Current Risk until 10 PM CDT this evening for the following zones: Bolivar Peninsula...Brazoria Islands... Galveston Island...Matagorda Islands. GM...Small Craft Advisory until 10 PM CDT 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...Galveston Bay...Matagorda Bay... 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. && $$
Thoughts: Lots of raining and lightning yesterday and today!
Minor flooding but much needed rain.
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