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
000 FXUS64 KHGX 120159 AFDHGX Area Forecast Discussion National Weather Service Houston/Galveston TX 859 PM CDT Tue May 11 2021 .UPDATE [NEAR TERM]... It was an interesting active weather day today with shower and thunderstorms firing up along a meandering frontal boundary early this afternoon. By mid to late afternoon, these storms quickly intensified with some producing wind gusts of 35 to 50 MPH, small hail, periods of heavy to torrential rainfall and frequent lightning as the boundary slowly progressed south. Some location received wind damage, but no injuries have been reported so far. As of 9 PM CDT tonight, the line of showers and storms now reside along the mid to upper TX coast and is expected to weaken within the next few hours. Models continue to show activity developing along portions of SE Texas overnight into early Wednesday morning, but severe storms are currently not expected. Winds will be breezy and variable with low ceilings developing later tonight. Only a few minor touch-ups were made to the forecast to reflect current conditions and updated weather trends. For additional information on the rest of the forecast, please refer to the previous short/long term discussion below. 24 && .PREV DISCUSSION... /ISSUED 709 PM CDT Tue May 11 2021/ AVIATION [00Z TAF ISSUANCE]... Quite the wx day for us today across SE Texas. Showers and storms were able to quickly intensify early this afternoon along a meandering frontal boundary. The stronger storms were able to produce torrential rainfall, frequent lightning, strong gusty winds and hail. KUTS at around 21Z had reported winds of 22 KTS with a gust of 42 KTS, and this was not the strongest storm out there today. Slowly these storms made their was south- southeastward with the strongest ones reaching Harris and Liberty counties by 6 PM CDT today. As the evening progresses, expect them to make their way further south gradually dissipating with the loss of heating. Some isolated to scattered activity may still occur during the night hours, but models show most of it ending or moving away from the local region by around 09Z. A mix of MVFR to IFR cigs expected once again through Wed morning, with the potential of some light rain or mist and patchy fog developing. Cigs should lift some Wed afternoon and could scatter out in some places. Winds turning northerly as the boundary pushed south and will remain through the end of the TAF period. 24 PREV DISCUSSION... /ISSUED 417 PM CDT Tue May 11 2021/ NEAR TERM [Through This Evening]... Severe Thunderstorm Watch is in effect through 9pm tonight for the northern portion of our CWA. Daytime heating (highs in the mid-to-upper 80s) has added to atmospheric destabilization leading to strong to severe storms in our northern counties. We have already had a confirmed tornado in southwestern Houston County earlier this afternoon. Interaction with the frontal boundary near Madison/Houston County led to the rotation in this thunderstorm. Also worth mentioning that EHI in this region is 2-3. Surface dewpoints in the 70s being advected northward south of the front added to its intensification. SPC has our northern and western counties in a slight risk for large hail, strong winds, and isolated tornadoes. With sufficient deep layer shear and instability available, these severe hazards will be possible in any isolated cells that are able to develop through the evening hours. Batiste SHORT TERM [Tonight through Wednesday Afternoon]... The frontal boundary will be the main focus for shower/thunderstorm activity going into tonight/tomorrow morning. Latest CAM guidance indicates convection developing along the frontal boundary over a line from Burleson County to Houston County and moving southward through the night. Due to the rainfall this area has received yesterday and today, went ahead and expanded the Flash Flood Watch out to Brazos County and as far south as Montgomery County. Additional rainfall totals of 1-3" are expected, but locally higher amounts are possible. Interestingly enough, a few hi-res models indicate an intensification of the thunderstorms as the front approaches the coast early Wednesday morning. There has been some semblance of consensus between models on two main lines of higher QPF totals with 2-4" in our northern counties and 2-4" along the coast. Currently leaning against a Flash Flood Watch for coastal areas for now since this area hasn`t received much rainfall lately. Models are not completely in agreement on the timing for the front moving off of the coast. The NAM is furthest behind with front pushing off the coast mid-morning on Wednesday. Most other models push the front off the coast in the early morning hours. Lingering moisture behind the front along with favorable jet dynamics can lead to post-frontal elevated showers throughout the afternoon hours. The good news is that afternoon temperatures tomorrow will be much cooler and below normal for most locations with highs north of I-10 in the upper 60s/mid 70s and upper 70s south of I-10. Batiste LONG TERM [Wednesday Night Through Tuesday]... High pressure builds in Wednesday night with rain chances tapering off across the north with lingering cloud cover. High pressure slides off to the east Friday into Saturday which will give the area 2 good days with drier air Thursday and Friday...cooler nights and pleasant days. Saturday though the weekend strong moisture return will be underway and have nudged up the rain chances from southwest higher to northeast lower chances. Some of the guidance is pointing to a very wet Sunday across the area with the potential for heavy downpours. Confidence for Monday and Tuesday is low with wildly varying solutions from persistent MCSs to a weak frontal boundary. At this point will strongly lean on the NBM given the uncertainty. MARINE... Winds have come down across the Gulf but locally on Galveston Bay stronger with the impressive moist inflow to the storms over SETX. Cold front pushes down into the coastal waters overnight/early Wednesday and will have the potential for strong storms with a wind threat. Post frontal SCEC conditions will be developing and could flirt with SCA. Moderate winds will prevail through Wednesday. The east and southeast flow will crank back up this weekend and expect a long stretch of SCEC/SCA conditions with seas of 4-6 feet and 15-25 knot winds prevail this weekend. 45 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 62 70 59 75 57 / 70 50 10 10 0 Houston (IAH) 69 76 61 79 60 / 80 50 20 10 0 Galveston (GLS) 72 79 66 78 70 / 80 60 30 10 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...Flash Flood Watch until 7 AM CDT Wednesday for the following zones: Brazos...Grimes...Houston...Madison...Montgomery... Polk...San Jacinto...Trinity...Walker. GM...Small Craft Advisory until 11 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. && $$ Update Discussion...24
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