Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
Issued by NWS Houston/Galveston, TX
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942 FXUS64 KHGX 150748 CCA AFDHGX Area Forecast Discussion...CORRECTED National Weather Service Houston/Galveston TX 248 AM CDT Wed May 15 2024 ...New SHORT TERM, LONG TERM, MARINE, CLIMATE... .SHORT TERM... (Today through Thursday Night) Issued at 246 AM CDT Wed May 15 2024 After some morning patchy fog, today promises to be very similar to yesterday. However, ridging aloft will be a tad more pronounced. Therefore, we may tack on an extra degree or two or three as compared with yesterday. Inland highs are expected to average around 90 degrees (~mid 80s at the coast). Humidity is expected to be relatively low once again (for Gulf coast standards), with afternoon dew points generally in the low 60s (upper 60s at the coast). While we enjoy the quiet toasty weather today, a mid/upper trough will move eastward over SW CONUS. The resulting PVA increase across western Texas/Oklahoma will induce LL pressure falls and gradually increase the pressure gradient across the Lone Star State. You will notice this via a return to SE LL flow from the Gulf. As SE flow continues into the evening and overnight hours, moisture from the Gulf will pool northward. A stalled frontal boundary (currently well offshore) is expected to lift northward through the night as a warm front, and stall over our CWA on Thursday. Where it stalls is somewhat uncertain, but the current data suggest it will be somewhere over our central or northern counties. The aforementioned trough moves into W Texas on Thursday. Its large scale PVA along with a parade of vort maxes embedded in the enhanced southwesterly subtropical jet aloft will bring plentiful synoptic scale ascent. HREF ensemble mean PWAT show widespread 1.8-2.2 inch values by Thursday afternoon across SE Texas. In the low levels, some of the data is hinting at the development of a sfc low pressure system over W Texas that could move eastward along the stalled boundary. This could impact the SE Texas atmosphere in a few ways. For starters, it could enhance LL S to SE flow. HREF 850MB ensemble mean winds suggest the development of a 25-35 kt LL jet. The low could also further enhance LL convergence along the boundary, providing a focus region for deep convective development. Instability south of the boundary could be high, with ensemble means indicating a good shot of 2000+ J/kg CAPE in what would be the inflow region of developing convection. So let`s talk about what this all means for southeast Texas. Generally speaking, there is a concern for heavy rainfall across most of the CWA. WPC has continued the Moderate Risk (Level 3 of 4) of excessive rainfall north of I-10 while most elsewhere is in a Slight Risk (Level 2 of 4). The continuation of the Moderate Risk is warranted for two primary reasons. The first being the antecedent soil conditions from recent heavy rains. Unfortunately, it may not take that much rain to result in flooding issues, especially across the Piney Woods region. The second reason is the placement of the boundary coupled with the overall synoptic set up. This is expected to favor deep convective development over our central and northern counties by Thursday afternoon. As Thursday afternoon progresses into Thursday evening and night, mesoscale processes may push the thunderstorm activity farther south. Widespread Thursday to Thursday night rainfall totals are expected to be 2-4 inches north of I-10, then drop to less than an inch near the coast. However, locally much heavier totals over 6 inches are possible. Though flooding is the primary concern, it is worth mentioning that a few thunderstorms could become strong to severe. SPC has placed areas north of I-10 under a Slight Risk (Level 2 of 5) for severe thunderstorms on Thursday. Areas farther south are under a Marginal Risk (Level 1 of 4). Damaging wind gusts and hail are the primary concerns, though a tornado cannot be ruled out. Self && .LONG TERM... (Friday through Tuesday) Issued at 246 AM CDT Wed May 15 2024 The storm system should be exiting our area off to the east on Friday. But before it goes, we could get one more shot of some showers/storms in the afternoon thru early evening hours. Hopefully, rainfall totals from this activity do not add too much to our already saturated locations. The previously mentioned break in our recent rain events is still on track beginning on Saturday and continuing into the first half of next week as ridging aloft builds across the state. This pattern change will shut down our rains. Friday will be the coolest of the days with afternoon highs in the 80s. Over the weekend and on into next week, highs will be mainly in the lower 90s, but we could see some mid 90s here and there. Lows during this period will be mainly in and upper 60s to low 70s range, but by Tuesday the 60s will likely disappear. Peak heat index values will be mainly in the upper 90s to low 100s, and heat safety precautions should be taken. 42 && .AVIATION... (06Z TAF Issuance) Issued at 1141 PM CDT Tue May 14 2024 Clear skies and light, variable winds can be expected across SE Texas overnight. Isolated patchy fog has already begun to develop late tonight. As this fog spreads, it may bring MVFR to IFR VIS thoughout portions of SE Texas during the early morning hours of Wednesday. All fog should burn off after sunrise, with winds strengthening and becoming southeasterly heading into the afternoon. Wednesday night, high clouds and isolated showers will be possible. 03 && .MARINE... Issued at 246 AM CDT Wed May 15 2024 Winds will transition to the east to southeast today, and this onshore flow will gradually strengthen and persist through the end of the week and into the weekend. Caution flags might be needed at times. Periods of unsettled weather are possible on Thursday and Friday, although highest shower and thunderstorm chances are anticipated inland. Brief offshore winds are possible if any storm complexes make it off the coast. Drier weather can be expected over the weekend and into early next week. 42 && .CLIMATE... Issued at 246 AM CDT Wed May 15 2024 Record high temperatures were set in Galveston and Palacios yesterday (May 14th). For Galveston, yesterday`s high temperature of 90 degrees broke the old record of 88 degrees that was last set in 2022. Galveston`s records date back to 1874. For Palacios, yesterday`s high temperature of 91 degrees broke the old record of 90 degrees that was set in 1959. Palacios`s records date back to 1943. 42 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 88 66 80 70 / 0 20 80 60 Houston (IAH) 89 69 85 72 / 0 20 80 60 Galveston (GLS) 84 74 83 75 / 0 10 50 60 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$