Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
Issued by NWS Houston/Galveston, TX
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574 FXUS64 KHGX 040935 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 435 AM CDT Sat May 4 2024 ...New SHORT TERM, LONG TERM, MARINE, HYDROLOGY... .SHORT TERM... (Today through Sunday Night) Issued at 431 AM CDT Sat May 4 2024 Weak impulses aloft with PWs in excess of 1.5" will bring isolated showers and thunderstorms across portions of SE Texas throughout most of today. Generally, showers and storms look to be weaker in nature, though we can`t completely rule out the potential for the occasional storm with a tad more potency. With rainfall being less widespread compared to previous days, highs across the region should climb into the 80s. A shortwave trough will enter Texas later this evening, bringing with it our our next "wave" of stronger storms and heavy rainfall. These storms should begin to fire up over Central Texas later tonight, tracking E/SE with the trough and entering our Northwestern counties near/in the Brazos Valley around midnight. Shower/thunderstorm coverage will later spread SE on Sunday. This environment will contain a weak LLJ, a deep warm cloud layer, saturated conditions in the mid/lower levels with PWs of 1.75-2.00 inches; indicating high precipitation efficiency and the potentially for locally heavy rainfall with these storms. CAM guidance generally places the highest rainfall totals further north across portions of the Brazos Valley/Piney Woods area, though the 00z & 06z runs of the HRRR suggest the possibility of heavier rainfall developing further south as well, including portions of the Houston metro area. CREST still shows swaths of soil moisture in excess of 40% north of I-10 and east of College Station. Meanwhile, RFC 1hr FFG remains around 2- 3" for most areas outside of our southwestern counties (North of I- 10 as well as east of I-45). A few locations even show 1hr FFG below 2" as well. WPC has SE Texas under a Slight (level 2/4) to Marginal (level 1/4) Risk of Excessive Rainfall during this overnight period into Sunday. A Flood Watch remains in effect for most areas along and north of the I-10 corridor, including the Chambers county and the Houston Metro area, until 1 PM on Sunday. An additional 1-3" of rainfall is expected with isolated higher amounts up to 5" possible in the watch area. Locally heavy rainfall in these storms may result in flash flooding, along with further exasperating ongoing flooding across SE Texas. While flooding remains the primary concern, sufficient instability and shear could allow for a few strong/severe storms to develop as well with the shortwave. WPC has ports of SE Texas under a Marginal (level 1/5) Risk of severe weather this weekend, with the strongest of these storms capable of producing damaging winds and hail. Storm activity looks to decrease in the evening hours of Sunday as the aforementioned shortwave exists to the east. However, weak impulses aloft may still bring isolated rain chances through late Sunday night. 03 && .LONG TERM... (Monday through Friday) Issued at 431 AM CDT Sat May 4 2024 From a significant wet period, we will transition to a hot weather pattern during the long term. Weak upper-level ridge will build across the middle/lower MS Valley while a strong upper-level low develops over the northern Rockies/High Plains. This pattern will bring a quasi-zonal flow aloft, that combined with southerly flow at the surface will bring warmer and more humid conditions across the region. This scenario looks to persist through the entire week. In fact, deterministic solutions keep suggesting 850mb temperatures climbing into the 20 to 25 degC Tuesday - Thursday. Ensemble solutions also keep suggesting this hot pattern, with values within the 99th to Max percentile of climatology per NAEFS and GEFS. With that being said, leaned towards a blend between NBM/NBM75th for MaxT through the week. Overall, look for highs mainly into the low to mid 90s. At the moment, Wednesday and Thursday look to be the hottest days with widespread readings into the low to mid 90s. Precipitation-wise, a relatively dry week is expected with only isolated to scattered activity possible during the day with the combination of diurnal heating and passing subtle shortwaves aloft Monday and after mid-week. Any of this activity is more likely to occur across our far northern counties; therefore, kept slight chances in the forecast over these counties. The next rain/storm chances look to arrive after Friday ahead and along of a weak frontal boundary. JM && .AVIATION... (06Z TAF Issuance) Issued at 1153 PM CDT Fri May 3 2024 A much quieter night is on tap with coverage through Sat afternoon remaining spotty as well. Moderate onshore winds are going to con- tinue overnight and should help to keep ceilings somewhat elevated until closer to sunrise. Winds will be strengthening a bit more as the day progresses on Sat as CIGs mix out. S/SE winds should be in the 6-12kt range tonight...then 12-20kts/G20-25kts tomorrow after- noon (higher near the coast). Did add the mention of VCSH(for now) to IAH (and CLL) as the next storm system approaches from the west tomorrow night through Sun morning. 41 && .MARINE... Issued at 431 AM CDT Sat May 4 2024 Moderate to occasionally strong onshore winds and seas between 3 to 6 ft will prevail this weekend and into next week. Small Craft Should Exercise Caution conditions will continue today due to winds and seas occasionally reaching 7 to 8 ft offshore. Scattered to numerous thunderstorms can be expected later tonight into Sunday as a disturbance moves through. Erratic wind gusts and higher seas can be expected near any strong/severe storms. Dry and hot weather with moderate onshore winds and seas generally up to 5 ft can be expected through the week. Beach conditions...there is a high rip current risk for all Gulf facing beaches through late this evening. JM && .HYDROLOGY... Issued at 431 AM CDT Sat May 4 2024 There is ongoing river flooding over parts of Southeast Texas, particularly along portions of the Trinity and San Jacinto rivers and a few sites along Brazos River. The following river points are at, or forecast to go to Major flood stage: - Trinity River (Riverside): Major Flood Stage - Trinity River (Romayor): Major Flood Stage - Trinity River (Liberty): Major Flood Stage - Trinity River (Goodrich): Major Flood Stage - Trinity River (Moss Bluff): Moderate forecast to go to Major - West Fork San Jacinto (Conroe): Major Flood Stage - West Fork San Jacinto (Humble): Major Flood Stage - San Jacinto (Sheldon): Major Flood Stage - East Fork San Jacinto (New Caney): Major Flood Stage - Navasota River (Normangee): Major Flood Stage - Menard Creek (Rye): Major Flood Stage Remember to heed any instructions from your local officials and to never travel through flooded areas or roadways. Please monitor updated forecasts via the NWS AHPS website and/or the new NWS NWPS webpage (https://water.noaa.gov/) as the river flood threat continues. JM && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 84 70 81 70 / 20 90 60 20 Houston (IAH) 84 73 82 71 / 20 60 50 20 Galveston (GLS) 80 74 80 73 / 20 30 30 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Flood Watch through Sunday afternoon for TXZ163-164-176>179- 195>200-212>214-300-313. High Rip Current Risk through this evening for TXZ436>439. GM...Small Craft Should Exercise Caution until 1 PM CDT this afternoon for GMZ350-355-370-375. && $$ SHORT TERM...03 LONG TERM....JM AVIATION...41 MARINE...JM