Houston area Flash Flood Watch: Friday PM through Sunday AM

The National Weather Service said this afternoon that a Flash Flood Watch will go into effect for much of Metro Houston (basically along and north/west of US-59/I-69) beginning Friday afternoon and continuing through Sunday morning. This includes the areas hardest hit by last week’s flooding.

Counties under the Flash Flood Watch Friday-Sunday (Iowa State/NWS)

Counties under the Flash Flood Watch Friday-Sunday (Iowa State/NWS)

 

As Eric pointed out this morning, there’s good reason for this. Most bayous in the city (Buffalo Bayou an exception) are back at their baseline levels. But, outside the city, streams, creeks, and bayous are running a few feet higher than normal still. And with a soggy ground any additional rain is unwelcome and can cause flooding concerns depending on how quickly it falls.

Basically, at this point all you need to do is continue to watch the forecast. There’s a bit less certainty with this event than there was last week. Also, it can’t be underscored enough that the rain totals implied by all models with this event aren’t anything like the last one. We want you to be prepared but not to panic here. We still don’t know exactly where the heaviest rain will fall, but we know there will be a few spots that see a pretty substantial amount of rain (not 15-20″ like last week, but 4-8″ in a few spots isn’t impossible).

So just stay tuned in through the weekend, especially if you have to travel around the area or live in an especially flood prone spot. We will have you covered.

TONIGHT & FRIDAY MORNING

In the near-term, we have a somewhat challenging forecast tonight and tomorrow.

If you believe the European model, heavy thunderstorms will flare up directly over Houston overnight. It may be the gold standard of weather models, but in this case it’s gone rogue. Most other weather models indicate that the next 12-18 hours will see just a chance of a few showers or a thunderstorm. I tend to agree, as absent really any big trigger, anything tonight should be sparse and directed north and west of the area.

Here’s the GFS 24 hour total precip between 18z today and 18z tomorrow (1 PM-1 PM):

GFS rainfall forecast overnight and Friday morning. (Weather Bell)

GFS rainfall forecast overnight and Friday morning. (Weather Bell)

 

So, that’s basically in line with the forecast above: A few showers around.

Our best high resolution short-range model, the HRRR, shows limited precipitation in the area tonight as well.

HRRR forecast rainfall through 4 AM. (Pivotal Weather)

HRRR forecast rainfall through 4 AM. (Pivotal Weather)

 

So it’s essentially the Euro versus the world right now. I would stick with a “chance of a few showers” forecast tonight for most of the region, with the best chance for some thunder in the Brazos Valley up toward College Station. We’ll continue to watch.

Rain chances will slowly tick upward tomorrow and especially tomorrow night closer to Houston; that’s when the concern for heavy rain and flooding will ramp up. More on that in the morning.

Posted at 3:00 PM Thursday

15 thoughts on “Houston area Flash Flood Watch: Friday PM through Sunday AM

  1. Ron

    Is there any web site/information source that regularly provides information on the depths and trends of bayous, creeks and reservoirs?

    Thanks./

  2. Worrybug

    1. Do you remain unconvinced that but we’re going to see the kinds of strong winds the we had on Wednesday morning again with the heavy rain this weekend?

    2.I’m also worried about lightning. Does excessive moisture mean twice as powerful cloud-to-ground lightning?

    1. Eric

      In regard to both questions, we cannot rule out the possibility of some severe weather in the form of damaging winds and lightning. However I am most concerned about the potential for heavy rainfall.

  3. Worrybug

    Sorry to bother you again, Eric, but I’ve been told by an arborist friend that falling trees from saturated grounds do not need a lot of wind as they usually fall very slowly lifting up the lawn, while higher winds will snap branches and full size trees and but will also lay them down intact with the root structure exposed.

    Now, does this mean we could STILL have thousands of homes without power even if the winds from the heavy rainstorms do not exceed say, 30 mph? I know it’s hard to predict, but what’s your best guess?

  4. ehssuut

    Thanks, Eric. Q.1 Any possibility to predict comparisons to Mem Day or Tax Day events?
    2. When will we know whether the Euro model is truly a rogue ? Pop up showers to the west?

    1. Eric

      1. Yes. It almost certainly won’t be bad.
      2. When models start to converge on a forecast outcome, then we’ll know whether the Euro is rogue or right (as is often the case).

  5. Armando D.

    Hi Eric! My dear Fulgencio has to drive from Dallas to Houston Saturday in the early afternoon. He has called me crying 5 times today. Is the forecast for Saturday any clearer so I can ease his pain? Thanks.

    1. Eric

      No. We’ve tried to be pretty clear that this rain event is unlikely to match those storms in terms of total precipitation.

  6. worrybug

    OMG, Eric and Matt! This is the hazardous weather outlook:

    .DAYS TWO THROUGH SEVEN…FRIDAY THROUGH WEDNESDAY

    A FLASH FLOOD WATCH IS IN EFFECT FRIDAY AFTERNOON THROUGH EARLY
    SUNDAY MORNING.

    HEAVY RAINS WILL BE POSSIBLE FIRST IN THE WEST FRIDAY AFTERNOON
    AND EXPANDING EASTWARD FRIDAY NIGHT AND SATURDAY. SCATTERED TO
    NUMEROUS STORMS SHOULD FORM AND MOVE SLOWLY THROUGH THE REGION.
    RAINFALL OF 2 TO 4 INCHES SHOULD BE COMMON WITH SOME AREAS SEEING
    AMOUNTS IN EXCESS OF 5 INCHES. IN ADDITION A SLIGHT RISK OF STRONG
    TO SEVERE THUNDERSTORMS WILL EXIST FRIDAY AFTERNOON AND NIGHT WITH
    THE PRIMARY THREAT BEING GUSTY WINDS AND HAIL. WITH THE GROUND
    BEING SATURATED A GREATER THREAT FOR TREES TOPPLING WILL OCCUR
    FROM THE GUSTY WINDS.

    That means people who didn’t lose their power on Wednesday WILL lose their power Friday/Saturday, right?!

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