Flash Flood Watch/Severe Weather Risk

Hello, folks! The fourth storm system this month has its eyes set on Texas and we're already feeling its effects. The upper level low is currently located in northern Mexico south of Arizona and is pushing disturbances across the state of Texas out ahead of it. These disturbances generate lift in our atmosphere. That lift helps to promote the development of showers and thunderstorms.

Image above courtesy of earth wind map and is depicting upper level winds over Mexico and the United States

Gulf moisture has already made a big return to the area as of Wednesday afternoon as evidenced by dew point temperatures in the upper 60s. At the surface a cold front is currently draped along the I-20 corridor across West Texas and is the focus for thunderstorm development this afternoon. Yellow shaded area north west of south central Texas is under a SEVERE THUNDERSTORM WATCH until 11pm CDT this evening. The storms outlined in red boxes are severe.

Texas Radar Update as of 5:20 pm CDT Tuesday evening

What should we expect in central Texas?

This evening/overnight:Widespread shower and thunderstorm activity will remain well to the north and west of our region tonight. A few thunderstorms may try and creep into northwestern areas of the Hill Country, but the storms will hold off for the I-35 corridor until Wednesday and especially Wednesday afternoon and evening. With that being said, a brief passing shower or downpour cannot be ruled out overnight and early Wednesday morning. Lows tonight will only manage the 60s area wide thanks to a persistent moist southerly breeze off of the Gulf of Mexico.

Wednesday Morning: Showers and storms may be ongoing across portions of the northwestern Hill Country and a large portion of west Texas slowly spreading south and east into the Hill Country during the early afternoon hours.

Wednesday afternoon/evening: Scattered showers and thunderstorms will begin to pop up along the I-35 corridor, becoming more widespread as a line of storms develops across the Hill Country and pushes slowly east through the I-35 corridor during the early evening hours. This is when the worst of the storms are expected in Austin/IH-35 corridor. In addition to the threat of locally heavy rainfall and dangerous cloud to ground lightning, the Storm Prediction Center based in Norman, Oklahoma has placed a large swath of central, south central, south, and southeast Texas under a SLIGHT RISK area for potential severe weather on Wednesday. This is a threat level 2 out of 5 and indicates that scattered severe storms will be possible, but the severe storms that develop will be short-lived and/or not widespread; however, an isolated intense storm or two is possible.

Forecast Radar Graphic (this is what one model believes the radar will look like at different times of the day on Wednesday)

Wednesday Severe Weather Threats

Flash Flood Watch (counties shaded in green)
in effect for the following counties: Travis, Williamson, Hays, Burnet, Blanco, Llano, and Gillespie from 7 am CDT Wednesday until midnight Thursday. Widespread amounts of 2-4 inches of rain will be possible in these locations with isolated higher amounts of up to 6 inches possible.

Images above courtesy of the Austin/San Antonio National Weather Service Forecast Office

Please remember, IF YOU COME ACROSS A FLOODED ROADWAY, TURN AROUND, DON'T DROWN!!!

Storms Likely Tonight

Forecast Discussion
A potent upper level storm system currently located over New Mexico will be bringing us the opportunity for thunderstorms late this evening and overnight. Out ahead of this storm system, sticky Gulf of Mexico moisture has infiltrated the region and combined with the approaching storm system and a surface dry line and cold front will be the fuel for a few isolated thunderstorms this afternoon and early evening (predominately for areas north and west of the Austin Area) and then widespread thunderstorms late evening into the early morning hours of Thursday for all of central and south central Texas. Storms that are able to develop this afternoon and early evening will have the potential to produce very large hail, damaging winds and isolated tornadoes. The most likely areas for this type of weather will be for areas north and west of the Dallas/Fort Worth Metroplex. I'm expecting quiet conditions across south central Texas until after 10 pm.

What to expect
Given the potent nature of this approaching storm system, severe weather will be possible across the area late this evening into early Thursday morning (pre-dawn). The Storm Prediction Center out of Norman, Oklahoma has placed a large swatch of north, central and south central Texas under an ENHANCED RISK for severe weather today/tonight. An enhanced risk is a level 3 out of 5 severe weather threat. The Storm Prediction Center defines an enhanced risk as "numerous severe storms possible" and the storms that develop will be "more persistent and/or widespread, a few intense."

Severe Weather Threat: Enhanced Risk (Orange shaded areas)
All modes of severe weather will be possible tonight (large hail, damaging winds, and perhaps an isolated spin-up tornado). I believe the greatest risks for the I-35 corridor will be the potential for some larger hail (potentially up to the size of golf balls) & some damaging wind gusts. Frequent and dangerous cloud to ground lightning and heavy rain will accompany all storms that develop.

Areas surrounding the enhanced risk area are in a slight risk (yellow shaded areas) category (threat level 2 out of 5)

What makes a thunderstorm severe?
A thunderstorm is considered to be severe by the National Weather Service if it's producing:

1. hail of at least of one inch in diameter or greater (quarter-sized)
2. and/or winds in excess of 58 mph or greater
3. and/or a tornado

Storm Timeline (High Resolution Rapid Refresh Model Imagery)

*times below are an estimate, line of storms will arrive along the I-35 corridor between 11:30 pm to 1:30 am

9 pm | Line of storms develops across the far western Hill Country 

11 pm | Line of storms pushing through the Hill Country (still west of the Hwy 281 corridor)

1 am | Line of storms overtakes the I-35 corridor

3 am | Residual light to moderate rains continue across the I-35 corridor; heaviest storms pushing through Lee & Fayette County

7 am | Line of storms pushing through east and southeast Texas 

How much rain can we expect?

On average 0.5 - 1.5 inches of rain...some areas out west will see less than that and some areas along and east of the I-35 corridor may see more than that. Flash flooding is not expected to be a concern at this time, but short-lived heavy downpours may result in minor street flooding late tonight/early Thursday. 

Thursday/Easter Weekend Outlook
All of this activity will quickly push east of the area by sunrise Thursday as high pressure builds in from the west leaving us with a sunny, gusty, and cooler day with highs in the 70s. Highs rebound into the 80s by the weekend with more cloud cover returning each day. No rain is expected.

***Please remain weather aware this evening and overnight and have a way to receive watches/warnings. It would be a good idea to have a flash light handy and your cell phones fully charged by midnight tonight just in case power goes out in your area.

Storm Chances Increasing

Thursday's Record Heat

The temperature soared to 92°F at Austin's Camp Mabry Thursday afternoon beating the previous record high of 89°F set back in 2017. Austin Bergstrom International Airport missed their record high of 92°F set back in 1958 by one degree. Abundant sunshine, abnormally dry conditions, and a down-sloping westerly component to the wind on Thursday allowed temperatures to soar. Keep in mind the average high temperature for this time of year is closer to 77°F.

Weekend Storm Chances

A series of upper level disturbances will be passing through the state of Texas this weekend and each disturbance will bring us a chance for showers and thunderstorms. A few of which will have the potential to be on the strong/severe side with large hail & damaging winds being the primary threats. The best chance for widespread showers and thunderstorms will come on Saturday (especially Saturday morning into early Saturday afternoon), but rain chances will begin to increase late tonight (most likely after 11 pm).

Severe Weather Risk: SLIGHT 

Given the potential for some isolated to scattered severe weather, the Storm Prediction Center out of Norman, Oklahoma has placed a large portion of central and east Texas under the SLIGHT RISK area for potential severe weather on Saturday and shifted the SLIGHT RISK area for potential severe weather farther east for Sunday. The severe weather threat will stay west of the area today. See outlooks below. 

Friday Severe Weather Risk Area

Saturday Severe Weather Risk Area

Sunday Severe Weather Risk Area

Understanding Severe Weather Risk Outlooks

Forecast Rainfall Accumulation

Between late Friday night through Sunday afternoon, 1-2 inches of rain may fall across central Texas with some areas potentially seeing more and some areas potentially seeing less. Areas west of the IH-35 corridor may see less than areas east. Flash flooding does NOT look to be a concern at this point in time, but if things do change always remember TURN AROUND, DON'T DROWN.

NWS Forecast Rainfall Accumulation (1-3 Day Outlook)

valid now through early Monday AM

Thunderstorms likely late tonight into Wednesday Morning

Weather Setup

A potent upper level storm system approaching Texas from the west will kick off a round of potential severe thunderstorms across far west Texas late this afternoon and evening that will congeal into a line of showers and thunderstorms that will move east late tonight and into the early morning hours of Wednesday before reaching the I-35 corridor before sunrise Tuesday morning. Storms should clear east of the I-35 corridor after the morning commute. Please plan accordingly for tomorrow morning given the expected thunderstorms. 

Widespread fog, mist, drizzle and low clouds this morning are thanks to a warm front moving north into the area from south Texas. Southeasterly winds have returned to both Austin and San Antonio and dew points and temperatures are rising behind the warm front. This warm front is sensing the approach of tonight’s storm system and is forced to move north. Plenty of sticky Gulf of Mexico Air is working its way north into the area. Despite temperatures in the 60s now, 70s are creeping north and will be here for this afternoon on breezy southeasterly winds. I'm not expecting much in the way of rain and thunderstorms this afternoon/early evening. Rain chances will really begin to increase after midnight and rapidly decrease from west to east by midday Wednesday morning. 

Forecast Radar (6 a.m. CDT Wednesday - Hi Res NAM Forecast Model)

Shows a line of strong storms along the I-35 corridor from the Oklahoma/TX Border to the Mexico/TX Border

Forecast Model image courtesy of COD Meteorology

How much rain are we going to see?

Given the progressive nature of the system, flooding does not look to be a concern. Rainfall amounts will generally average 0.25 to 0.50 inches with amounts of 0.75-1 inch not out of the question. 

Will we see any severe weather with these storms?

The best opportunity for severe weather (large hail, damaging winds, and tornadoes) will remain well west of central Texas across west and far west Texas where the Storm Prediction Center out of Norman, Oklahoma has placed those locations in an enhanced risk for severe weather today & tonight. Portions of the Hill Country from roughly the Highway 281 corridor and west have been placed under the slight risk category for severe weather today & tonight and areas along the I-35 corridor have been placed under the marginal risk category for potential severe weather (the lowest risk category). The biggest issue for us along the I-35 corridor is going to be brief heavy downpours, frequent cloud to ground lightning, and potentially some strong, gusty winds along some portions of the line of storms as it moves through the area tomorrow morning. 

What do these severe weather risks mean ???

Image courtesy of the NWS Austin/San Antonio Forecast Office

Tuesday’s Severe Weather Risk Areas

Wednesday’s Severe Weather Risk Areas

What can we expect behind the storms?

Sunshine, dry air and warmer temperatures! Highs behind tomorrow morning’s storms will rebound into the 70s thanks to a breezy west southwesterly wind behind tomorrow morning’s Pacific cold front. Some locations may climb into the lower 80s. Cooler weather will make a return to the area beginning on Thursday and really becoming noticeable Friday into the upcoming weekend and highs drop down into the 50s/60s and overnight lows dip down into the 30s/40s. 

Please remain weather aware and have a way to receive watches/warnings issued by the National Weather Service. Make sure you have a safety plan in place when and if severe weather should strike. It is always a good idea to be situationally aware. 

Chilly Weekend in Store, but nowhere near as cold as originally advertised

Forecast Discussion

The return of sunshine today has allowed temperatures to climb into the 70s across the majority of central Texas this afternoon. As of 3 p.m. CST, the temperature at Austin’s Camp Mabry has climbed to 74° and along the west runway at Austin Bergstrom International Airport, the temperature has climbed to 77°.

Low clouds and areas of fog will build back in across the area late tonight as temperatures cool into the upper 40s to lower 50s across the region. Increased cloud cover on Friday can be expected ahead of our next frontal system that will be cooling things off in a big way for the upcoming weekend. While the bulk of the really cold air associated with this next cold front will stay well north and east of central Texas, we will have just enough of it around to make for a chilly weekend. Forecast models were initially indicating a significantly colder air mass to move into the area earlier this week, but models have warmed significantly over the past couple of days and are indicating that rain chances will be much smaller than originally anticipated for Friday and Friday night as the much advertised cold front blows through the area.

Saturday Forecast Map (surface fronts, sea level pressure, precipitation type)
Forecast map valid 6 a.m. Saturday Morning

Day by Day Forecast

Let’s break down the forecast day by day through the weekend and into your M.L.K Holiday

Tonight: 53° | low clouds increase with areas of fog developing

Friday: 71° | dreary morning gives way to a mainly cloudy, but mild afternoon; 20% chance of a shower along and especially east of the Interstate 35 corridor

Friday Night: 45° | Cold front approaches the area from the northwest and sparks a 30% chance for a shower or brief thunderstorm late (especially east and southeast of the Austin Metro Area)

Saturday: 56° | Mostly sunny, WINDY, and much colder; wind gusts over 30 mph possible

Saturday Night: 36° | Mostly clear, breezy and cold; light freeze possible north & west of Austin

Sunday: 57° | Sunny and cool

Sunday Night: 38° | Mainly clear & chilly

M.L.K Day: 65° | Mainly sunny & warmer with a southerly breeze

*Temperatures above reflect downtown Austin

Slight Risk of Severe Weather Tuesday

SLIGHT RISK OF SEVERE THUNDERSTORMS TUESDAY

The Storm Prediction Center (SPC) has placed the majority of central and north Texas (from Austin north) in the SLIGHT RISK category for potential severe weather on Tuesday. According to the Storm Prediction Center, a SLIGHT RISK of severe weather means scattered severe storms will be possible. The severe storms that are able to develop are typically short-lived and NOT widespread, however, an isolated intense storm cannot be ruled out. 

Areas shaded in yellow are under a SLIGHT RISK for severe weather...dark green areas are under a MARGINAL RISK

A deep trough of low pressure (a large dip in the jet stream) to our west will continue to get closer to the area through the day on Tuesday and cross the area late Tuesday into Wednesday. Out ahead of this trough, a surface cold front is being pushed east southeast towards central Texas. As this front and the upper level dynamics provided by the trough approach the area, showers and thunderstorms are expected to blossom. The showers and thunderstorms we experienced today are occurring as deep moisture continues to be pulled into the state of Texas ahead of the approaching dip in the jet stream. 

According to the Storm Prediction Center, some of the storms that develop on Tuesday will have the potential to become strong and/or possibly severe with damaging winds in excess of 58mph being the greatest risk. In addition to the potential for some damaging thunderstorm wind gusts in a few spots, the threat for heavy rainfall and deadly cloud to ground lightning will occur with any and all storms that develop. Storms will come in waves through the day on Tuesday as disturbances move across the area from southwest to northeast ahead of the advancing trough of low pressure. Storm chances will eventually come to an end with a broken line of showers and storms late Tuesday afternoon and evening as a Pacific cold front pushes across the area from west to east with a reinforcing shot of cooler and drier air moving in from the northwest early Wednesday morning setting the stage for a beautiful Wednesday, Thursday, and Friday with noticeably more pleasant conditions thanks to a cooler and drier air mass that will infiltrate the region.

Additional rainfall amounts of 1-4 inches will be possible between now and late Tuesday night across central Texas with the heaviest totals being felt along and west of the I-35 corridor. Due to already saturated soils, it will not take a lot of rain for creeks and streams across the area to rise. Remember, if you come across a flooded roadway, TURN AROUND, DON’T DROWN. As always please remain weather aware and keep an eye to the sky. 

This approaching trough of low pressure that is giving us showers and storms is working in tandem with a ridge of high pressure centered across the east coast to steer Hurricane Michael (now forecast to make landfall as a MAJOR category three hurricane with sustained winds of 115 mph and gusts near 140 mph) in the Florida panhandle Wednesday afternoon. In addition to the threat of high winds and torrential rainfall, Michael is also expected to bring a significant storm surge. Here’s a look at key messages from the National Hurricane Center on Hurricane Michael:

As of the 7pm Monday evening advisory from the National Hurricane Center, Hurricane Michael is a category one hurricane with maximum sustained winds of 85 mph. Below is a look at the 7pm Monday evening official forecast track:

Key Messages:

1. Life-threatening storm surge is likely along portions of the

coasts of the Florida Panhandle, Big Bend, and Nature Coast, and a

storm surge warning is in effect for these areas. Residents in these

areas should follow all advice given by their local officials.

2. A hurricane warning has been issued for portions of the Florida

Gulf Coast, and everyone in these areas should prepare for

life-threatening winds associated with the core of Michael.

Damaging winds will also extend inland across portions of the

Florida Panhandle, southern Georgia, and southeast Alabama as

Michael moves inland.

3. Heavy rainfall from Michael could produce life-threatening flash

flooding from the Florida Panhandle and Big Bend region into

portions of Georgia and South Carolina.

To stay up to date with all of the latest information regarding Hurricane Michael, please visit the National Hurricane Center's website by clicking HERE  

Rain Looks Promising

Forecast Discussion

With high pressure positioned well to the east and northeast of Texas, the sea breeze was able to once again push through the area this afternoon. As it did so, it helped to generate some widely scattered showers and thundershowers. With the loss of daytime heating this evening, any remaining showers will quickly fizzle out. The sea breeze is simply a gust of wind that moves in off of the Gulf of Mexico that tries to equalize temperatures. Because land heats up a lot faster than water, low pressure develops and forces "cooler" air over the Gulf of Mexico to rush in land to takes it place. It acts like a mini cool front this time of year.

Sea Breeze Graphic

Saturday
I'm expecting a near repeat of today's weather on Saturday, morning low clouds will give way to a partly cloudy and warm afternoon in the lower to middle 90s with afternoon/evening showers and storms popping up for some folks as the sea breeze moves through the area.

Father's Day & Beyond
Deep tropical moisture associated with an area of low pressure currently located over the northwestern Caribbean and Yucatan Peninsula will move northwest towards Texas over the weekend and approach the Texas coast by Father's Day. This approaching area of low pressure (which the National Hurricane Center is giving a 10% chance of tropical development this evening) will drag copious amounts of Gulf moisture into the Lone Star State for the second half of your Father's Day Weekend into the middle of next week. Because we will have so much moisture in place, I expect widespread tropical showers and storms to blossom up each afternoon beginning on Father's Day with even better chances for widespread tropical showers and storms Monday and Tuesday of next week. These showers and storms will be driven by the heat of the day, becoming widespread during the late morning/afternoon and decreasing each day towards sunset with the loss of daytime heating. Forecast models have been a bit wishy-washy in terms of forecast rainfall accumulation, but I'm thinking given the amount of moisture that's going to be in place, we could easily manage 1-3 inches of rain across the area between now and the middle of next week. Because of the tropical connection, showers and storms that develop will be capable of producing very heavy rainfall in a short amount of time. Another benefit of the added clouds and rain will be cooler temperatures. Afternoon highs after Father's Day (depending on when the rains flare up each day), will likely only manage the upper 80s.

Tropical Moisture Location (as of Friday evening)

Forecast Rainfall Accumulation - now through next Friday
Source: Weather Prediction Center (WPC)

At this point in time, flash flooding is not a concern, as most of this rain looks to fall over several days, but it's always important to remember that if you come across a flooded roadway, turn around, don't drown!