September 2019 - Warm End of September

[Andrew]

To give a reference to how much moisture is expected to cross into the region, Lake Charles historical data suggests max PWATs for this time of the year are approximately 2.5 inches. Based on the ECMWF output, some areas could see PWATs near 3 inches.

[djmike]

It's pouring in Beaumont....wow! Wasn't expecting this today.

Where are you located? I'm downtown by Julie Rogers....coming down good...

Im off MLK and Washington area by Exxon Refinery. Still pouring. Wouldn't be surprised if some roads here start flooding...Sheesh.

[unome]

updated https://spacecityweather.com/monday-aft ... -to-texas/

[Samantha550]

Picking my daughter up at MKCHS off College. The rain was blinding heading here. We may meet the rain estimates today for the entire event here.

[djmike]

Picking my daughter up at MKCHS off College. The rain was blinding heading here. We may meet the rain estimates today for the entire event here.

Its pretty heavy in Beaumont. And the main event hasn’t even begun.

[unome]

updated https://www.wpc.ncep.noaa.gov/discussio ... isc=qpferd

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
407 PM EDT Mon Sep 16 2019

Day 3
Valid 12Z Wed Sep 18 2019 - 12Z Thu Sep 19 2019

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR THE MIDDLE
AND UPPER TEXAS COAST...

...20Z Update...
Shifted heaviest QPF inland and increased amounts as guidance
supports better organization and heavy rainfall over much of
north/central TX coast (WFO HGX) through Day 3. Expect 2-4+
inches with locally higher amounts, especially adjacent coast
which includes Houston/Galveston. Uncertainties still remains
with the placement and organization of this disturbance, with
antecedent conditions from Day 2 QPF also a factor to consider.
Regardless, all indications point to very heavy rainfall across
this region with some locations receiving well above normal
precipitation through Day 3 which may result in more widespread,
significant flash flooding. After careful coordination with the
surrounding WFOs, expanded the Slight and added Moderate Risk to
account for coastal flooding concerns and urban sensitivities to
expected higher rain rates.

EEnIXoWUUAACkzo - Copy.jpg

[srainhoutx]

As unome posted, the late afternoon Updated graphics are being released. The WPC has increased their 5 Day Quantitative Precipitation Forecast and it does show higher potential rainfall totals for our Region.

[DoctorMu]

Mark Nissenbaum has LCH, HGX & CRP radars on his site active right now

http://moe.met.fsu.edu/~mnissenbaum/radar.html

you can increase the # of frames, speed up, make gif, etc... love his fsu pages

Yeah - that's a closed rotation.

[DoctorMu]

12z Euro shows some areas at 30+ inches FWIW.

The gradient between 1.6 in and 16 in of rain could to be ridiculous

[stormlover]

https://www.tropicaltidbits.com/analysi ... 91618&fh=1


Nam puts Houston and Beaumont on blast

[djmike]

https://www.tropicaltidbits.com/analysi ... 91618&fh=1


Nam puts Houston and Beaumont on blast

Oh no...we don't need THAT much rain in Beaumont. This would just be another Harvey event for us. I hope no one gets this much. Wonder if the NAM is sniffing an eastern shift with the core.

[unome]

updated

Code: Select all

Area Forecast Discussion
National Weather Service Houston/Galveston TX
359 PM CDT Mon Sep 16 2019

...Potential heavy rain and flash flood event setting up Tue 
night thru Thurs...

.SHORT TERM [Through Tuesday]...
Showers and isolated thunderstorms have remained south of a line 
from Colorado to Conroe this afternoon, with gusty winds in and 
around stronger storms. Short term models have struggled to 
initialize well with the placement of the convection, with the RAP13 
probably doing the best as of late. Trends in radar imagery east of 
the region over W LA has pushed convection further inland than what 
we have see over our area this afternoon. With winds out of the 
east, expect we could see further development of precipitation over 
our northeastern zones through the remainder of the afternoon hours. 
Convection should continue to shift further inland, moving into 
Trinity and Polk counties over the next hour or so. In general, 
expect most of the convection to wane shortly after sunset this 
evening, with a lull in activity overnight and into early tomorrow. 
Redevelopment of showers and thunderstorms will be possible early 
Tuesday morning, once again starting over the Gulf waters before 
pushing further inland by mid-morning. The region of disturbed 
weather associated the upper-level low pressure system will continue 
to shift to the northwest over the next few days and with it will 
drag ample tropical moisture across the region. That said, 
precipitable water values of 2.2 to 2.4 inches should advect inland 
across the bays and Gulf waters and along the coastal counties by 
the afternoon hours tomorrow. Therefore, anticipate more widespread 
showers and thunderstorms tomorrow in comparison to today as the 
upper level low tracks closer to the upper Texas coast. Main impacts 
associated with this precipitation will be the potential for 
localized heavy downpours and gusty winds associated with stronger 
storms. The threat for periods of heavy rainfall will be possible 
starting late Tuesday as this system shifts closer to SE TX. This 
threat should continue over the next few days...more details in the 
long term section below.  Hathaway

&&

.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
  likely 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. 

.LONG TERM [Thursday night Through Monday]...
Look for this system to eventually head further north and away
from se Tx as the ridge just to the north slightly erodes. Moisture
levels and rain chances will diminish and temperatures go back 
up.  47

&&

.MARINE...
A slow area of disturbed weather associated with an upper level low 
pressure system is continuing to shift towards the northwest this 
afternoon, bringing with it tropical moisture. Winds out of the east 
associated this system remain between 15 to 20 knots with gusts up 
to 25 knots at times in and around storms. Small craft should 
continue to exercise caution through at least tomorrow morning 
across the Gulf waters and both Matagorda and Galveston Bay. Winds 
will continue to turn more out south to southeast tomorrow, and 
eventually more out of the south to southwest by Wednesday. The SCEC 
currently in effect will likely need be extended through at least 
Wednesday. The risk for strong rip currents also remains possible. 
Seas in the offshore waters look to range between 4 to 6 feet, but 
elevated seas will be possible in and around stronger storms. By 
Friday and into the weekend, both winds and seas will lower as the 
pressure gradient weakens across the region. 

Additionally, tide levels are continuing to run about 1.5 to 2.0 
feet above normal. At Galveston Bay Entrance, tide levels could peak 
at 3.0 to 3.4 feet above MLLW during high tide. High tide values of 
this nature will continue at least through tomorrow and Wednesday 
before slowly lowering beneath the 3.0 feet threshold. A Beach 
Hazards statement is in effect to cover both the risk for strong rip 
currents, as well as the elevated tide levels and impacts that are 
possible. Hathaway

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  74  92  73  89  74 /  10  60  20  80  60 
Houston (IAH)          76  89  76  86  75 /  30  60  70  90  90 
Galveston (GLS)        80  87  79  86  79 /  80  80  90 100  80 

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 1 AM CDT Tuesday for 
     the following zones: Coastal waters from Freeport to 
     Matagorda Ship Channel TX out 20 NM...Coastal waters from 
     High Island to Freeport TX out 20 NM...Galveston 
     Bay...Matagorda Bay...Waters from Freeport to Matagorda 
     Ship Channel TX from 20 to 60 NM...Waters from High Island 
     to Freeport TX from 20 to 60 NM.


&&

$$

[TexasBreeze]

Cpv17 can't like the trends. That area may not see too much and Beaumont may take the brunt as usual with these tropical events according to the eastward model shifts/nam.

[djmike]

Does seem that every tropical system pinpoints a landfall then they always slowly shift eastward the closer landfall gets.

[unome]

thread https://twitter.com/pppapin/status/1173699306039021568

no invest, no meso floater

[jasons2k]

Update from Jeff Lindner:

Heavy rainfall threat increasing for SE TX

Flash flooding will be possible especially mid week

Discussion:
Ill defined area of broad low pressure over the NW Gulf of Mexico within a surface trough just to the east of an upper level low pressure system nearing the middle TX coast. Showers and a few thunderstorms have rotated inland today northward to roughly the I-10 corridor with brief heavy rainfall and gusty winds. Broad area of low pressure will move generally toward the Matagorda Bay area and may become slightly better defined on Tuesday into early Wednesday morning. Low level wind field respond to the slight deepening of the low and show a decent onshore flow developing Tuesday night over the central portions of the area. Moisture levels will begin to surge upward on Tuesday and remain extremely high levels into Wednesday and Thursday as surface low/trough meanders N west of I-45 across the region. Concern increases Tuesday night onward for the potential for training and clusters of heavy rainfall to move south to north over the region on that favored east side of the surface low/trough.

Rainfall Amounts:
Model output today has been in fair agreement on the placement of the heavier rainfall across portions of SE TX, but vary wildly on the expected amounts. Best course of action at this time is to follow WPC guidance and blend the various amounts and locations in a more smoothed fashion instead of taking the extremes on either end of the model spectrum. Widespread rainfall amounts of 4-6 inches is likely with isolated totals of 10-15 inches. The widespread amounts may need to be raise more if guidance continues with its increasing signal.

With the atmosphere becoming increasingly saturated, storms will become very efficient rainfall producers and hourly rainfall rates of 2-4 inches will be possible which will lead to rapid flash flooding over streets and areas of poor drainage.

Flood Potential:
While grounds are very dry across the region with current 2 inch depth soil moisture running 20-30% across much of Harris County, intense rainfall rates and the gradual saturation of the soils will lead to increasing run-off potential. Timing of rainfall amounts will be critical in the eventual outcome of flooding and the degree. Sustained heavy rainfall over several hours will likely result in flooding while frequent bands with breaks in between the bands will help allow the rainfall to soak in some and reduce the amount of run-off. Given the current forecasted rainfall amounts, run-off especially by mid week looks likely with significant rises on area creeks, bayous, and rivers possible.

WPC has increased the threat for flash flooding into the moderate category for portions of the area on Wednesday.

Timing: onset Tuesday (scattered), heavier more sustained rains (Wednesday-Thursday)

Amounts: widespread 4-6 inches, isolated 10-15 inches

Street flooding: high

Channel flooding: moderate (up to 6 inches), high (over 6 inches) in a 6 hour period

[srainhoutx]

thread https://twitter.com/pppapin/status/1173699306039021568

no invest, no meso floater

Levi has a manual floater up...

https://www.tropicaltidbits.com/sat/sat ... product=ir

[sau27]

For what its worth the Tx Tech WRF keeps heaviest accumulations off shore. We see this a lot in these scenarios. Convection sets up just off the coast and blocks inflow inland. Just another possibility to keep in mind here.

[jasons2k]

FWIW the wind is starting to really gust up here.

[Cpv17]

I hope areas out west can get at least a couple inches. Western areas of the viewing area is where the rain is most needed.