September 2019 - Warm End of September

[Cpv17]

Our Houston-Galveston NWS sums the knowns and unknowns very well in this afternoon’s Area Forecast Discussion and why need to be weather aware through the rest of week:

.MID TERM [Tuesday Night Through Thursday]...
What we know:
- Ground will gradually become increasingly saturated with periods of rainfall and more prone to runoff.
- Upper low will make its way northward into southeast Texas, but ikely stall and meander over the area due to higher pressure to the north.
- Moisture levels will be near record peak values recorded this time of year. Rain rates of 1-3"+ per hour are possible at times. Heavy rain in a short amount of time will be the primary trigger for street flooding and rises on area creeks, bayous and rivers.
- A weak surface low will slowly move northward from the Coastal Bend to near the Matagorda Bay area Tuesday night and Wed morning setting the stage for the first potential round of heavy rainfall...possibly in the form of training convective bands closer to the circulation itself...gradually spreading out thru the day with heating.
- In very general terms, the surface low will meander northward Wed & Thur...possibly situated between the Brazos Valley and I-45 late in the period.
- Multiple rounds of precipitation are expected with some
intermittent breaks in between.
- There will be changing, potentially large run-to-run swings of model solutions. Don`t focus on just one. Just know the overall conditions are favorable for heavy rain which could cause flooding.

What are some of the unknowns:
- Just how organized or unorganized atmospheric conditions line-up for prime and/or significant amounts of rain.
- Specific rain amounts. There will be several inches spread out over several days. Focus on the impacts!
- Specific timing/location of the periods of heaviest rainfall.
Can occur at any time and any place. They`ll be dependent on several variables which can be difficult to determine even 6-12 hours out. Just know there are signals there for significant rain and associated flash flood impacts.
- Specific river/creek/bayou impacts. It`ll be dependent on where and how much rain falls. Rises and flooding impacts can be expected where the heaviest rain occurs.

That’s an excellent write up!

[jasons2k]

They keep saying moisture will be near "record levels" for "this time of year".

It's September. It's THE time of the year for high levels of moisture. It's kinda like when they say it's going to be "unseasonably cold" in the middle of December. Like there's another season besides winter for cold weather.

I think Mets sometimes struggle with the nuances of the English language.

[Cpv17]

I feel like the NAM 3km has a pretty good handle on this right now and it says the heaviest rains will be just to my east. Only has about 1-2” for me, but I’m only about 20 miles away from 8+”.

[don]

They keep saying moisture will be near "record levels" for "this time of year".

It's September. It's THE time of the year for high levels of moisture. It's kinda like when they say it's going to be "unseasonably cold" in the middle of December. Like there's another season besides winter for cold weather.

I think Mets sometimes struggle with the nuances of the English language.

When they are referring to moisture they mean precipitable waters which some of the models show approaching 3 inches, that's very high and is record territory.

[jasons2k]

They keep saying moisture will be near "record levels" for "this time of year".

It's September. It's THE time of the year for high levels of moisture. It's kinda like when they say it's going to be "unseasonably cold" in the middle of December. Like there's another season besides winter for cold weather.

I think Mets sometimes struggle with the nuances of the English language.

When they are referring to mousture they mean precipitable waters which some of the models show approaching 3 inches,thats very high and record territory.

I understand that - it was about the "this time of year" comment. It's September, not January. They could simply say "near record levels" period.

[swell]

They keep saying moisture will be near "record levels" for "this time of year".

It's September. It's THE time of the year for high levels of moisture. It's kinda like when they say it's going to be "unseasonably cold" in the middle of December. Like there's another season besides winter for cold weather.

I think Mets sometimes struggle with the nuances of the English language.

Daily max Precipitable Water from past LCH soundings in the next couple days was 2.35. Don't see the problem
https://www.spc.noaa.gov/exper/soundingclimo/

[djmike]

Picked up over 1” today from Mr. Lows outer rain bands. 3 more days to go and will prob see a lot more. Have a gut feeling the core rains will meander east a bit on qpf but just my opinion. Just from seeing core originally started out over corpus yesterday and now core will be houston. Thats quite a shift. We will see....

[unome]

They keep saying moisture will be near "record levels" for "this time of year".

It's September. It's THE time of the year for high levels of moisture. It's kinda like when they say it's going to be "unseasonably cold" in the middle of December. Like there's another season besides winter for cold weather.

I think Mets sometimes struggle with the nuances of the English language.

for reference, from https://www.spc.noaa.gov/exper/soundingclimo/

Screenshot_2019-09-16 Storm Prediction Center Sounding Climatology Page - Copy.png

Screenshot_2019-09-16 Storm Prediction Center Sounding Climatology Page - Copy.png

[Tx2005]

How far east have things shifted today? I’m assuming Eastern Harris County is in the thick of things now?

[Andrew]

How far east have things shifted today? I’m assuming Eastern Harris County is in the thick of things now?

Nothing has changed today from earlier this morning. Most models indicate widespread 5-8 inches with isolate pockets of 15 inches possible. Unfortunately, forecasting where the heaviest rain will fall will likely be a "nowcast" type of situation where we have to wait for it to start raining or at least get a couple of hours out. Also, expect multiple rounds of rain with the largest areas of concern being Tuesday night and Wednesday night.

[Cpv17]

How far east have things shifted today? I’m assuming Eastern Harris County is in the thick of things now?

Eastern Harris County is definitely right there in the mix.

[jasons2k]

Why do I get the feeling that this is going to be an overachiever? I’m not worried about it becoming very intense or anything but I think it does ramp up before coming ashore and it will bring a lot of problems with it. pic.twitter.com/3Ei2YxaRrW
-- Mark Sudduth (@hurricanetrack) September 16, 2019

[stormlover]

we now have an invest

[srainhoutx]

Interesting that the NHC waited so long on designating 98L. The ensembles have been extremely bullish on TC genesis the past couple of days.

[mcheer23]

18z euro

[djmike]

18z euro looks eastward now more boliver side rather sw hou. Forecasted 3” at first for beaumont, now showing 7” with this run. Wonder if this will be a trend.

[stormlover]

Yep euro shifted eastward

[TexasBreeze]

Gotta watch that area circulating due south of Gal and due east of Corpus. It has a nice developed circulation with a persistent red t-storm cell attached to it. It has increased banding north of it too.

https://radar.weather.gov/ridge/radar_l ... Z&loop=yes

[Rip76]

Interesting tonight.

[unome]

Interesting that the NHC waited so long on designating 98L. The ensembles have been extremely bullish on TC genesis the past couple of days.

frustrating, but glad they finally did http://hurricanecity.com/models/models. ... stinvest=1

Code: Select all

AL, 98, 2019091600,   , BEST,   0, 271N,  920W,  15, 1010, DB,   0,    ,    0,    0,    0,    0,    0,    0,   0,   0,   0,    ,   0,    ,   0,   0, GENESIS024,  ,  0,    ,    0,    0,    0,    0, genesis-num, 024, 
AL, 98, 2019091606,   , BEST,   0, 271N,  927W,  15, 1010, DB,   0,    ,    0,    0,    0,    0,    0,    0,   0,   0,   0,    ,   0,    ,   0,   0, GENESIS024,  ,  0,    ,    0,    0,    0,    0, genesis-num, 024, 
AL, 98, 2019091612,   , BEST,   0, 271N,  935W,  15, 1010, DB,   0,    ,    0,    0,    0,    0,    0,    0,   0,   0,   0,    ,   0,    ,   0,   0, GENESIS024,  ,  0,    ,    0,    0,    0,    0, genesis-num, 024, 
AL, 98, 2019091618,   , BEST,   0, 272N,  943W,  20, 1010, DB,   0,    ,    0,    0,    0,    0,    0,    0,   0,   0,   0,    ,   0,    ,   0,   0, GENESIS024,  ,  0,    ,    0,    0,    0,    0, genesis-num, 024, 
AL, 98, 2019091700,   , BEST,   0, 273N,  950W,  20, 1010, DB,  34, NEQ,    0,    0,    0,    0, 1012,  150,  90,   0,   0,   L,   0,    ,   0,   0,     INVEST, S,  0,    ,    0,    0,    0,    0, genesis-num, 024, SPAWNINVEST, al772019 to al982019,