textproduct: Brownsville/Rio Grande Valley

This forecast discussion was created in the public domain by the National Weather Service. It can be found in its original form here.

SHORT TERM

(Tonight through Monday night) Issued at 1257 PM CST Sun Nov 3 2024

Key Messages:

* Breezy south-southwest winds to continue through Monday. Will continue to monitor the need for a Wind Advisory.

* Well above average temperatures are expected to persist through Monday night.

* Hazardous marine/coastal conditions to continue through Monday- Monday night. Venomous moon jellyfish observed at SPI and likely Boca Chica Beach to make swimming even more hazardous.

Amplified 500mb large-scale pattern, featuring an anomalously strong mid-upper trough over the interior West U.S., a rather potent early Autumn sfc low pressure system over the 4-Corners Region extending into the eastern plateau of the Sierra Madre Oriental, and an anomalously strong downstream mid-upper ridge and sfc high over the eastern U.S. will help to drive a windy weather regime across Deep South Texas and the Rio Grande Valley with warmer than normal temperatures through the short-term forecast period. This will result in adverse to hazardous marine/coastal conditions as well through the short-term forecast period.

This evening through Monday, the large scale and synoptic layout as described above will enhance the pressure gradient and activate a strong low level jet (LLJ) over the region. Forecast models are showing a plume of 925-850 mb winds sampled between 25-40 kts during this time. Increasing mixing (momentum xfer) heights up the dry adiabat to about 900 mb should help to mix some of these winds down to the surface through Monday. That said, 40+ mph winds can't be ruled out during the day on Monday and a Wind Advisory may be needed. V-component winds based off the NAEFS are indicating winds from the 850mb to the sfc ranging between 1-3 STDEVs above normal with the strongest of winds over the western Gulf of Mexico northward into eastern Texas. Right now, forecast wind gusts are between 30-35 kts, which is just short of Wind Advisory criteria. Have opted to let the overnight crew further evaluate the potential for Monday.

Strong warm air advection (WAA) aided by breezy south- southwesterly winds will help to drive unseasonably warm temperatures for early November standards across Deep South Texas and the Rio Grande Valley as daytime highs on Monday are expected to range 5-10 degrees above normal with values between 89-95F. With dewpoints (Td) ranging between 70-75F degrees, max heat indices are expected to range between 97-105F, with the hottest of heat indices located over a Starr/Hidalgo County to Brooks/Kennedy County corridor. Winds will begin to subside Monday evening with decreasing mixing heights amid the loss of daytime heating and as the field of strongest winds shifts further away to the northeast. Overnight low temperatures Monday night will remain well above normal levels (by 8-15F degrees) with values ranging between the mid 60s northwest to the mid 70s southeast.

LONG TERM

(Tuesday through next Sunday) Issued at 1257 PM CST Sun Nov 3 2024

The tail end of a cold front ahead of a deep, 500 mb trough over the high Plains Monday night will push into South Texas by Tuesday morning. Ongoing degraded beach conditions, including elevated rip current risk, minor coastal flooding from beach water runup during high tide cycles, and elevated surf will likely continue into the early part of the forecast before briefly improving by midweek.

Layer PWAT will approach 2 inches by Tuesday morning with scattered showers and thunderstorms developing along and ahead of the cold front. Eastern sections will be in a general thunderstorm outlook on Tuesday. Though the front could wring a a few tenths to a half inch of rain out of the atmosphere through the AM, rain chances will end rather quickly from west to end on Tuesday afternoon as drier air surges into the region.

In the wake of the front, light to moderate north winds and cooler weather will take over Tuesday and Tuesday night. Temperatures on Tuesday will generally be in the 70s to lower 80s, falling into the 50s and 60s Tuesday night. The cooler weather will be short- lived, however, as onshore flow will return fairly quickly on Wednesday. High temps will rebound into the 80s. The aforementioned cold front will retreat northward across the area as a warm front by Wednesday night. Low temps will rebound to near 70 Wednesday night. Temps in general will be well above normal following the the cold front into the latter half of the week.

The latest model guidance maintains the theme of a strong western Atlantic upper ridge extending into parts of the East while a strongly digging western US trough likely closes off a low near the Four Corners around midweek, followed by a slow eastward drift and some northeastward acceleration over the Plains by the weekend. That system will spin off another surface front which will push into central and possibly south Texas by Friday, where it is progged to stall out.

Showers and thunderstorms are showing signs of organization in association with a low pressure system over the south-central Caribbean Sea. Though climatologically, overall tropical activity plunges in November, some areas, especially where there is warm water, can support late season tropical development. The Caribbean system may become a tropical depression during the next day or two as it moves generally northward toward Jamaica, the Cayman Islands, and Cuba. Looking ahead to mid and late week, some long range model solutions take the system north into the Gulf of Mexico. Should that occur, the lower Texas coast may (by late week) experience longer period swell which could negatively impact coastal conditions like rip current risk, beach water runup and surf height. Stay tuned.

AVIATION

(00Z TAFS) Issued at 434 PM CST Sun Nov 3 2024

A breezy to windy onshore flow will prevail at the aerodromes through the next 24 hours with partly cloudy skies. MVFR to VFR is anticipated with precipitation not likely to occur.

MARINE

Issued at 1257 PM CST Sun Nov 3 2024

Tonight through Monday Night...An enhanced pressure gradient over the region will continue to lead to breezy south-southwesterly winds and thus continued hazardous marine/coastal conditions through Monday night. A Small Craft Advisory remains in effect for the Laguna Madre till Monday evening and the Gulf Waters till Tuesday morning. A High Risk for Rip Currents will remain in effect along the local area beaches to at least Monday evening.

Tuesday through Friday night...A cold front is expected to push offshore the lower Texas coast Tuesday morning, shifting winds to north. While no marine hazards are yet in place for the beginning of the long term, it will be possible for low end small craft advisory conditions (mainly seas) from the short term to bleed over into the first period of the long term, Tuesday. North winds will be short- lived, however, as southeast winds will develop by late Wednesday into Thursday. As winds steady up from the east on Thursday, seas will once again build, aided in part by a potential tropical system moving from the Caribbean into the central and eastern Gulf. SCEC to low end SCA conditions could develop on the Gulf Thursday night through Friday night.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 78 88 77 82 / 0 0 20 50 HARLINGEN 75 90 73 80 / 0 0 20 50 MCALLEN 78 94 74 82 / 0 0 30 30 RIO GRANDE CITY 74 95 69 80 / 0 0 30 10 SOUTH PADRE ISLAND 80 85 79 82 / 0 0 20 60 BAYVIEW/PORT ISABEL 76 88 74 82 / 0 0 20 60

BRO WATCHES/WARNINGS/ADVISORIES

TX...High Rip Current Risk through Monday afternoon for TXZ451-454- 455.

GM...Small Craft Advisory until 6 PM CST Monday for GMZ130-132-135.

Small Craft Advisory until 6 AM CST Tuesday for GMZ150-155-170- 175.


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