Area Forecast Discussion
Issued by NWS Brownsville, TX
Issued by NWS Brownsville, TX
Versions:
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
227 FXUS64 KBRO 270530 AAB AFDBRO Area Forecast Discussion...UPDATED National Weather Service Brownsville TX 1230 AM CDT Mon May 27 2024 ...New AVIATION... .SHORT TERM... (Tonight through Monday night) Issued at 237 PM CDT Sun May 26 2024 Key Messages: * Excessive, Dangerous, Record-Breaking Heat Monday * High Rip Risk through Monday * Marginal Severe Weather Risk Northwest portions Monday afternoon/evening There will be little relief from the frying pan heat in the short term. Mid-level ridging (595 dam) anchored over Mexico will provide strong subsidence across deep South Texas and the Rio Grande Valley. Dangerous heat will persist Monday with triple-digit temperatures (up to 109 in the Upper Valley) for most non-coastal locales. Due to steady southeast surface flow, dew points poking well into the 70s will support elevated heat index values ranging from 115 to 120 degrees for a few hours Monday afternoon. This would support an excessive heat warning. Record high temperatures may be tied or broken (see climate section below). Looked at the NBM and also looked at mixing in the ConsShort but the results were similar. Tonight and Monday night temperatures will remain warm with lows in the upper 70s across the Northern Ranchlands to the lower 80s across the Lower Rio Grande Valley. Interestingly, SPC now places portions of the RG Plains, Brush Country, and Upper Valley in a marginal severe risk for late Monday afternoon/evening. Looking at the models, a promising source will be earlier initiating convection over South Texas that propagates south into the Northern sections of the CWA. Outflows could contribute to follow-on storms. Convection moving out of the Sierra Madre Oriental Range is also an ongoing possibility. In any case, isolated stronger storms could deliver large hail and strong, damaging winds from Monday afternoon into the late evening. Though storms tend to move smartly along, brief downpours could result in a quick inch of rain. && .LONG TERM... (Tuesday through next Sunday) Issued at 237 PM CDT Sun May 26 2024 Key Messages: -Well above seasonal temperatures will continue through the long term forecast period -More Heat Advisories are likely for each day for the duration of the long term forecast period. While the current model trend have continued to show the center of the subtropical ridge move slightly to the south-southwest as a group of shortwave troughs move towards the east starting on Tuesday and continuing through Friday. While this will allow for the temperatures to come down by a degree or two. High temperatures are still going to be in the range of upper 90s along the coast and the barrier island, while triple digits will persist over the rest of the region. Looking at the experimental HeatRisk tool, a mixture of Major to Extreme heat risk is present Tuesday through Saturday. Considering that surface winds remain out of the southeast through next Sunday, plenty of humidity will flow into the region. The combination of the heat and the humidity will allow the heat indices to rise. The current model analysis shows that the heat indices will be in the range of 109 to 113. However most of Deep South Texas and the Rio Grande Valley has more heat indices closer to 111 to 113. Even at night, the temperatures are expected to be hot. As low temperatures are expected to be in the range of upper 70s to low 80s through out the region. Since there will be still plenty of humidity at night the heat indices will still be high. Based on the current model analysis the nightly heat indices are expected to be in the range of low 80s to low 90s. As for the rain chances, they remain very limited at best. Isolated showers are possible on Tuesday for Starr and Zapata, but after that point, the rain chances drop off. Most of the long term forecast period is pretty expected to be rain free. && Moderate to breezy southeast winds will scatter out the low clouds by mid day Monday. .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... Issued at 237 PM CDT Sun May 26 2024 Tonight through Monday night...Mostly moderate southeast breezes and moderate to slightly enhanced wave heights will prevail through the forecast. High pressure over the Gulf will provide the driving force for the seasonal winds. Small craft may at times need to exercise caution. Tuesday through Next Sunday...Light to moderate onshore flow with moderate seas are generally expected to continue through next weekend. However a locally enhanced pressure gradient will pick up starting on Wednesday that will result in a period of Small Craft Exercise Caution for the Laguna Madre. Then on Friday the winds and seas will pick up resulting in the need for Small Craft Exercise Caution for the Laguna Madre and Gulf waters. A low end Small Craft Advisory cannot be ruled out at this point either. && .CLIMATE... Record Highs for Monday May 27, 2024 Brownsville 99 in 1973 (Forecast high 99) Harlingen 100 in 2018 (Forecast high 101) *A break in the climate records McAllen 107 in 1973 (Forecast high 104) && .PRELIMINARY POINT TEMPS/POPS... BROWNSVILLE 82 96 81 95 / 0 0 0 10 HARLINGEN 79 98 79 97 / 10 0 0 10 MCALLEN 81 101 81 100 / 10 10 10 10 RIO GRANDE CITY 80 102 78 102 / 20 10 10 10 SOUTH PADRE ISLAND 82 87 82 87 / 10 0 0 10 BAYVIEW/PORT ISABEL 80 93 80 93 / 10 0 0 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...54-BHM LONG TERM....64-Katz AVIATION...63-KC