A flood watch has been issued for parts of Central Texas as multiple rounds of downpours and storms are expected over the next few days. The National Weather Service says most of Central Texas is under a flood watch from this evening to Friday evening. There is a moderate to high risk of street, flash and river flooding, especially on Thursday.
The tropical moisture is in place, and a low pressure system and front will collide into the moisture to help turn on the rain. The slow-moving front will be the focal point for storm development, and lift from upper levels will keep the storms going strong. The flooding risk stays to the west today and tonight, but then the region is in the middle of the Level 3, or moderate, risk of flooding Thursday.
On average 2 to 4 inches of rain is possible, but isolated areas will get 4 to 6 inches. Where the highest totals will occur will be the biggest forecast challenge. Two rounds are expected. The first round comes early in the day with scattered storms, moderate rain and lightning. The second round will happen late on Thursday with widespread heavy rain, strong storms, flooding risk, small hail and gusty winds. The flooding risk will be the main concern, but there will be a marginal risk of small hail and brief strong winds. Information from meteorologist Zack Shields.
Meanwhile, Hurricane Polo made landfall across the northern Mexican state of Sonora on Tuesday afternoon. After dissipating, some of the storm’s remnant moisture traveled into parts of New Mexico and West Texas, bringing heavy rainfall to the region. Now, as an incoming cold front interacts with the leftover Pacific moisture, flooding rain is likely to expand across a large part of Texas.
According to the National Weather Service, between 2 and 4 inches of rain are expected across much of South-Central Texas through Saturday, but isolated rainfall amounts could reach 8 inches in a few spots. “Much of this is going to be beneficial rainfall across most areas of South-Central Texas,” the weather service said in a web briefing on Tuesday, “but where the highest pockets of rainfall set up will be the risk area for flash flooding.”
In San Antonio, a flood watch will go into effect at 7 p.m. Wednesday. However, the greatest risk of flooding is not expected until Thursday, when the front moves closer to the Interstate 35 corridor. For the most part, dry weather is expected in San Antonio on Wednesday, but the air will be very humid. Morning temperatures will sit in the mid- to upper 70s, rising into the upper 80s by noon. A brief morning shower is possible, with rain chances expected to be near 30 percent.
By Wednesday afternoon, temperatures are expected to reach 93 to 95 degrees under partly cloudy skies, but heat index values could peak as high as 104 degrees. An isolated storm will remain possible, but with just a 20 percent chance of rain in San Antonio. Overnight, thunderstorms are expected to start moving through the Edwards Plateau and Hill Country, bringing the region’s initial threat of flooding.
Thursday morning, storm chances are expected to rise significantly as a potential line of thunderstorms moves from the Hill Country eastward toward the Interstate 35 corridor. The San Antonio metro area will see about a 50 percent chance of rain between 4 a.m. and 8 a.m., but chances will rise to around 80 percent after 8 a.m. Scattered heavy downpours are possible. Midday Thursday, scattered off-and-on thunderstorms are expected to continue with about a 70 percent chance of rain across the metro area between 11 a.m. and 4 p.m. Some storms could produce intense rainfall rates of more than 2 to 3 inches per hour, resulting in flash flooding. A few isolated storms may also be strong, capable of producing small hail and damaging winds of up to 60 mph. An isolated tornado is also possible, although the overall threat is very low.
Thursday evening and night, the cold front is expected to move slightly south and east of San Antonio. Scattered thunderstorms will remain possible, but chances will depend on the placement of the front. If it moves too far away, rain chances would decrease significantly. If the front stays closer, rain will continue. “Thursday night through Friday will be the hardest part of the forecast given the uncertainty in the timing and placement of the cold front,” the National Weather Service said.
Friday morning and afternoon, rainfall is likely to redevelop along the stalled cold front, bringing more off-and-on showers and thunderstorms through the morning hours. San Antonio will have about a 70 percent chance of rain between 4 a.m. and 9 a.m. Friday, and heavy downpours could cause flooding across city streets and highways across San Antonio. Rain chances will fall to 50 percent during the afternoon and evening. Chances for scattered showers will continue into the weekend, with about a 40 percent chance of rain Saturday, followed by a 20 percent chance on Sunday. The flood threat, though, will decrease significantly, as most rainfall will be light.
The cold front will also bring cooler air into the region, allowing temperatures to cool to slightly below-average levels for early October. Temperatures are likely to reach the mid- to upper 80s on Thursday before falling further into the lower 80s by Friday, Saturday and Sunday. Meanwhile, morning temperatures are likely to hover near 70 degrees over the weekend before finally falling into the upper 60s by the start of next week. By the middle of next week, afternoons will likely warm slightly back into the mid-80s, while mornings stay in the upper 60s.
In North Texas, a multi-day stretch of wet, stormy weather is heading toward the region, bringing rising flood concerns and relief from unseasonable heat ahead of a weekend cold front. FOX 4 Weather Chief Meteorologist Dan Henry talks about the timing for storms that will hit the Metroplex overnight and early Thursday morning. While Wednesday morning is starting out quiet, warm, and windy, scattered showers and thunderstorms are expected to develop by the afternoon, particularly along and west of Interstate 35W. Areas west of the Metroplex are under a marginal risk for severe weather — a level 1 out of 5 — with the primary threats being gusty winds up to 60 mph and small hail smaller than quarters. The tornado threat remains very low.
A flood watch has been issued and extended through 7 a.m. Friday. Widespread totals of 2 to 4 inches are expected over a 24- to 48-hour period, with isolated amounts reaching 5 to 6 inches. Because the ground in the region is exceptionally dry, rapid runoff will quickly heighten the risk of localized flooding, especially as storms train over the same areas tonight and into Thursday morning. Temperatures on Wednesday will peak near 92 degrees under humid conditions, accompanied by gusty winds ranging between 25 and 30 mph even before storms arrive. The City of Fort Worth is providing free sandbags to residents starting today to help prepare for potential flooding from upcoming heavy rain and storms.
Conditions will remain unsettled through Thursday and Friday as an upper-level system stalls to the west, triggering multiple rounds of precipitation. A true cold front is slated to sweep through on Friday, ushering in much-needed cooler conditions. Highs late in the week and into the weekend will drop into the upper 70s and lower 80s, with morning lows dipping into the comfortable low to mid-60s. Scattered showers will linger into Saturday before coverage decreases on Sunday, leading to a drier start to next week.
