September 2019 - Warm End of September

[srainhoutx]

Even the 12Z Legacy GFS suggests 5 to 10 inches with some isolated totals of 12 inches+ over SE Texas.

[jasons2k]

Heard a mention here and there about a core rain event potentially being the cause for all the rain. How strong does a tropical system have to be in order for a core rain event to even happen? I thought this was more typical when a strong storm comes ashore and dumps all at once as it weakens.

It does not have to be strong at all. Remember, Allison didn’t flood out Houston until she had moved well inland towards the ArkLaTex region and looped back. And there has been many a ‘core event’ recently in the Texas Hill Country just from ‘tropical like’ ULL systems.

In short, it does not have to become a TS to dump that much rain.

[jasons2k]

Starting to see some hints of convergence bands setting-up within the cumulus field over land. We may see some bands of rain forming this afternoon as things heat up.

[txbear]

WRF sniffing the heavy rain potential as well. Although heaviest confined mostly offshore, trend increasing from the bay and on to the NW.

[sau27]

Heard a mention here and there about a core rain event potentially being the cause for all the rain. How strong does a tropical system have to be in order for a core rain event to even happen? I thought this was more typical when a strong storm comes ashore and dumps all at once as it weakens.

It does not have to be strong at all. Remember, Allison didn’t flood out Houston until she had moved well inland towards the ArkLaTex region and looped back. And there has been many a ‘core event’ recently in the Texas Hill Country just from ‘tropical like’ ULL systems.

In short, it does not have to become a TS to dump that much rain.

Since Allison I have been fascinated with core rain events, yet I have not been able to find much literature on them. It is always a thought in the back of my mind when these weak systems meander on shore around here.

[DoctorMu]

Canadian beginning lighter FWIW. GFS sticks to 3-5 in overall with a hot/wet spot around a foot SW of Katy.

[DoctorMu]

Heard a mention here and there about a core rain event potentially being the cause for all the rain. How strong does a tropical system have to be in order for a core rain event to even happen? I thought this was more typical when a strong storm comes ashore and dumps all at once as it weakens.

It does not have to be strong at all. Remember, Allison didn’t flood out Houston until she had moved well inland towards the ArkLaTex region and looped back. And there has been many a ‘core event’ recently in the Texas Hill Country just from ‘tropical like’ ULL systems.

In short, it does not have to become a TS to dump that much rain.

Since Allison I have been fascinated with core rain events, yet I have not been able to find much literature on them. It is always a thought in the back of my mind when these weak systems meander on shore around here.

Harvey feasted on nightly core events.

[DoctorMu]

Even the 12Z Legacy GFS suggests 5 to 10 inches with some isolated totals of 12 inches+ over SE Texas.

Latest CMC, GFS, Legacy 12Z are 1/2 has much precip.


I guess watering for half the usual time worked

[Cpv17]

At the rate this is trending east, this may end up over Beaumont and into Louisiana.

[srainhoutx]

I continue to see some very strong signals via the MJO and the strongest Convectively Coupled Kelvin Wave of the Hurricane Season supporting an active period in both the Pacific and Atlantic Basins. I will not be surprised to see a flurry of tropical activity as we end September and begin October.

09162019 MJO diagram_40days_forecast_GEFS_member.gif

09162019 MJO ECMF_phase_51m_small.gif

09162019 twc_globe_mjo_vp200.png

09162019 CCKW twc_mjoCCKW_vp200.png

[don]

This tropical disturbance is starting to look interesting...

https://tropicaltidbits.com/sat/satloop ... roduct=vis

[unome]

just an fyi - WPC should update QPF days 1-3 by approx 18Z https://www.wpc.ncep.noaa.gov/html/fam2.shtml#qpf

a QPF webinar, from March 2016, if you have the time https://www.wpc.ncep.noaa.gov/html/webi ... html5.html

[Cpv17]

On the next Euro update at 12z, I would expect to see the heavier totals shift east once again. Probably over Galveston and then Baytown then north into Liberty County. Seems about right seeing the east trends. Chances of rain diminishing with each model run for the western parts of the viewing area.

[cperk]

This tropical disturbance is starting to look interesting...

https://tropicaltidbits.com/sat/satloop ... roduct=vis

Looks like something trying to form.

[jasons2k]

Just stepped outside for lunch. A stiff breeze from the northeast....like a tropical system is brewing in the Gulf

[tireman4]

Just stepped outside for lunch. A stiff breeze from the northeast....like a tropical system is brewing in the Gulf

Nope. Nothing to see here sir. Move on toward Fall.

[cperk]

On the next Euro update at 12z, I would expect to see the heavier totals shift east once again. Probably over Galveston and then Baytown then north into Liberty County. Seems about right seeing the east trends. Chances of rain diminishing with each model run for the western parts of the viewing area.

What is the basis of your line of thinking on this east shift ,because no one else here is talking about it.

[sau27]

I think it is important to keep a couple of things in mind here.

-We all know how these heavy rain events, particularly when associated with disorganized tropical blobs, work. The QPF bombs will bounce around each model run. Just like we try to advise not obsessing over every wobble of the eye of a tropical system, we shouldn't put too much stock into exactly where these bulls eyes are placed run to run. Focus more on the general area.

-Today is only Monday and the main part of this event isn't forecast until late Wednesday into Thursday. While that may not be a lot of time for certain events, these types of set ups tend to be more now-cast events.

-Finally, the 00z Euro is what set all of this heightened alert into motion. Yes, some other models have latched on to the general solution this morning, but lets get a few more runs in before talking about trends. For all we know the 12z Euro in a couple of hours could be just as much of a surprise as the 00Z was this morning.

[mcheer23]

Disorganized showers and thunderstorms over the northwestern Gulf of
Mexico are associated with a broad area of low pressure. Some slow
development of this system is possible before it moves inland along
the northwestern Gulf coast Tuesday tonight or Wednesday. Regardless
of development, this system is expected to produce locally heavy
rainfall along portions of the central and upper Texas coastal areas
later this week.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...low...20 percent.

[jasons2k]

20% again.