Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
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015 FXUS64 KBRO 270845 AFDBRO Area Forecast Discussion National Weather Service Brownsville TX 345 AM CDT Mon May 27 2024 ...New SHORT TERM, LONG TERM, MARINE, CLIMATE... .SHORT TERM... (Today through Tuesday) Issued at 217 AM CDT Mon May 27 2024 Key Messages: * Excessive, Dangerous, Record-Breaking Heat today * High Rip Risk through late this evening * Marginal Severe Weather Risk Northwest portions this afternoon/evening Mid-level ridging (595 dam) anchored over Mexico will provide strong subsidence across Deep South Texas and the Rio Grande Valley. Dangerous heat will continue today with triple-digit temperatures ranging from around 100 degrees along the I-69E corridor to near 108 degrees across the Rio Grande Plains. High temperatures will range from the mid to upper 80s at the beaches to the 90s near the coast. Record high temperatures may be tied or broken (see climate section below). Due to steady southeast surface flow, dew points climbing well into the 70s will support elevated heat index values ranging from 115 to 122 degrees for a few hours this afternoon. Therefore, an Excessive Heat Warning in effect for today. Some convection may develop over the Sierra Madre Oriental Range and drift towards the Rio Grande Plains this afternoon as a weak shortwave traverses around the periphery of the 500 mb ridge. The latest GFS is more robust with convection developing and then moving into the Rio Grande Plains around sunset. However, confidence remains low on convection coverage this afternoon and evening due to the spread in the current CAM models. Lean towards a mix of the NBM and ConsShort for pops for today into tonight. In any case, isolated stronger storms could deliver large hail and strong, damaging winds this afternoon into the late evening. Any of the heavier storms may produce brief downpours and could result in a quick inch of rain. SPC has portions of the Rio Grande Plains, Brush Country, and Upper Valley in a marginal severe risk for late this afternoon into the evening. While, the Mid to Lower Valley and the coast remain in a general thunderstorm outlook. Low temperatures tonight will remain warm with lows in the upper 70s across the Northern Ranchlands to the lower 80s across the Lower Rio Grande Valley. Models continue to indicate the center of the 500 mb subtropical ridge shifting slightly to the south-southwest and should allow for a minor lowering of high temperatures on Tuesday. However, daytime high temperatures and heat indices will remain well above normal on Tuesday. Highs on Tuesday are expected to range from the mid to upper 90s across the coastal counties to the triple digits (100 to 104 degrees) across the Mid to Upper Valley and the Rio Grande Plains. There is a medium (40-60 percent) probability of Heat advisories occurring Tuesday afternoon. Also, the Experimental NWS Heat Risk Index continues to show Major to Extreme (4-5 out of 5) on Tuesday for the risk of heat-related impacts. Another opportunity of rain (low chance) is on Tuesday afternoon as convection from the higher terrain of Mexico drifts towards the Rio Grande Plains. SPC has most of Deep South Texas in a general thunderstorm outlook for Tuesday. The persistence moderate southeast winds over the Gulf of Mexico will continue to drive a moderate swells towards the Lower Texas Coast through the period. Therefore, a continuation of a High Rip Current Risk is expected through this evening. && .LONG TERM... (Tuesday Night through Sunday) Issued at 217 AM CDT Mon May 27 2024 The aforementioned 500 mb subtropical ridge will remain the dominant feature over the BRO CWFA through the period, with the center of this feature varying from the upper east coast of Mexico to just south of the Baja Peninsula. Although dry weather will prevail through a majority of the time for Deep South Texas and the Rio Grande Valley, isolated showers and thunderstorms are occasionally possible, and primarily over the northern ranchlands (Zapata, Jim Hogg, Brooks, and Kenedy counties). This will be due to convection initiating over neighboring Mexico courtesy of mid- level shortwaves and then migrating into ranchland area. Additionally, well above normal daytime high and overnight low temperatures will also occur. Forecast heat indices for the long term forecast period suggest that a HEAT ADVISORY is most likely for inland portions of the BRO CWFA Friday and Saturday, with a SPECIAL WEATHER STATEMENT Wednesday, Thursday, and Sunday in lieu of the HEAT ADVISORY. Ultimately, will see if this regime holds as the new work week progresses. Finally, the intensity of the pressure gradient, with thermal low pressure over Mexico interacting with building high pressure over northeast Mexico, may result in a WIND ADVISORY for the three immediate coastal counties (Cameron, Willacy, and Kenedy) on Friday and maybe even Saturday. && .AVIATION... (06Z TAFS) Issued at 1225 AM CDT Mon May 27 2024 A mix of VFR/MVFR ceilings and light to moderate southeast winds prevail across Deep South Texas early this morning. Widespread MVFR ceilings are expected to develop overnight. Low cloud decks then should decrease after sunrise, with VFR conditions returning to all RGV aerodromes by mid-morning. Some intermittent visibility reductions are possible through the period, as haze/mist could briefly drop visibility to 5-6 miles, though confidence is too low to include in the TAF. Light winds overnight will increase and become gusty later this morning into the afternoon. && .MARINE... (Today through Tuesday) Issued at 217 AM CDT Mon May 27 2024 Low to moderate southeast winds and moderate to slightly enhanced wave heights will prevail through the period. High pressure across the Gulf will provide the driving force for the seasonal winds. Small craft may at times need to exercise caution. (Tuesday Night through Sunday) Steadily increasing winds and building seas will occur along the Lower Texas Coast through the period. This will be due to thermal low pressure over inland Mexico gradually interacting more intensely with high pressure building over the northeast Gulf of Mexico. Small Craft Should Exercise Caution be will a certainty, with Small Craft Advisory becoming more likely beginning Friday and continuing through the end of the period. && .CLIMATE... Issued at 217 AM CDT Mon May 27 2024 Record Highs for today May 27, 2024 Brownsville 99 in 1973 (Forecast high 99) Harlingen 100 in 2018 (Forecast high 101)- break in the climate record McAllen 107 in 1973 (Forecast high 104) && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 97 82 96 81 / 10 10 10 0 HARLINGEN 100 79 98 78 / 10 10 10 10 MCALLEN 104 82 101 80 / 20 10 10 10 RIO GRANDE CITY 104 80 102 78 / 20 20 10 20 SOUTH PADRE ISLAND 87 82 87 82 / 10 10 10 10 BAYVIEW/PORT ISABEL 94 80 93 80 / 10 10 10 10 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...Heat Advisory until 11 AM CDT this morning for TXZ248>255-353. Excessive Heat Warning from 11 AM this morning to 8 PM CDT this evening for TXZ248>255-353. Heat Advisory until 8 PM CDT this evening for TXZ351-354-355. High Rip Current Risk through this evening for TXZ451-454-455. GM...None. && $$ SHORT TERM...Caceres-63 LONG TERM/UPPER AIR...Tomaselli-66