Texas Fall-2015

[fendie]

If Hurricane Patricia continues trending further westward could the vorticity associated with the storm never make it over the NW GoM and end up remaining over land? I guess this may be what the models were showing the last few cycles before the 12z runs. Wouldn't that lead to less moisture transport and upper level dynamics for the upper Texas coast? Certainly it would mean a shorter duration of storms for eastern Texas since a coastal low could linger for days.

Certainly an interesting setup and it looks to be all about timing and where the ingredients come together for high rain rates in training storms. That pacific fetch of mid and upper level moisture is quite impressive, will be interesting to see what Patricia decides to cook up for the lone star state.

[JDawg512]

Winds are really starting to pick up especially over the last hour or two. The moisture is returning with a vengeance.

[gpsnowman]

Yes, very sticky outside this evening. At least we know this humidity will bring rain. Lots and lots of rain.

[Ntxw]

From Ryan Maue's tweet



State average rainfall 4.51"! Can you imagine most locales getting that on average for the state? Texas is a huge state, the trllions and trillions of gallons of water to be unleashed. Can the water sheds hold that much water in such large coverage area? In May the water reservoirs and rivers were at record low levels when the rains came. So while flooding was bad to catastrophic in some places, we aren't starting with empty sheds to cover.

[Ntxw]

Patricia is about to undergo rapid intensification. Could be a cat 3 or even cat 4 at landfall. It's path will play a role in who sees more than just 4-5".

[gboudx]

From McCauley:

The atmosphere is loading up with humidity just in time for the arrival of our cold front and upper-level disturbance that will bring widespread rain to much of the state of Texas, including a 100% coverage across all of north Texas. The tropical low in the Gulf of Mexico is still not expected to form until late in the weekend, so it will NOT be blocking Gulf moisture from moving in and thus it will not be preventing soaking rains to move across our part of the state (you will recall this was a concern last week regarding this upcoming rain event).

I am going to add an inch to earlier rainfall projections and go for 2-5 inches for the Metroplex with some local amounts in excess of 6 inches by the weekend.

But again, since we are still more than 24 hours away from the main rain event, we may need to adjust those numbers. I don't trust the math when we are more than 24 hours out from a heavy rain.

For example, some computer models are going for 1 to 4 inches across the Metroplex, while others are going for 4 to 18 inches across the Metroplex (yes, that's an "18" !) I think that model is way off base, but it just shows you the difficulty in predicting rainfall amounts more than 24 hours out with a system like this. Needless to say, we're all going to get soaked!

Flash flooding also continues to be a concern even though it has been bone dry for so long. Rainfall rates will exceed 1 inch per hour from time to time in some of the heavier storms, and that can cause flash flooding no matter how dry it has been. Also, remember, atmospheric conditions will be favorable for "storm training" which means some of the storms will follow one right after the other over the same location yielding several inches of rain which could lead to flash flooding.

So stay tuned for updates. Forecast rainfall amounts may change, but I don't think we will have to change the 100% coverage!

[weatherdude1108]

Winds are really starting to pick up especially over the last hour or two. The moisture is returning with a vengeance.

I was just out and about also and noticed the strong breeze. Definitely feels more like the Caribbean out there!
Also, my new electronic gauge has picked up 0.05 of an inch so far today. We had a passing shower an hour or so ago. It picked it up. At least I know it is working when I am not testing it.

[1900hurricane]

Patricia is generating the deepest convection I've ever seen in the eastern Pacific (-90*C tops). The upper level moisture streaming off is going to be extremely rich.

[Ntxw]

Patricia is generating the deepest convection I've ever seen in the eastern Pacific (-90*C tops). The upper level moisture streaming off is going to be extremely rich.

http://rammb.cira.colostate.edu/product ... 220245.GIF

I would concur, I would be even more impressed if she was able to sustain it. You don't see it too often for that long in the WHEM mostly in the WPAC. With such cold tops, should an eye clear and fast she may have time to push high end cat 4 maybe even cat 5 but that would require very good timing before land interaction.

To understand the scope look at the rest of the hemisphere, to the west is major hurricane Olaf. You can compare how deep her convection is, extremely moist.

[Ntxw]

Lighting up in the south plains radar. Setting up the band that will shift east/se and should stall over the I-35 corridor. Once that happens look out. Radar estimates 4-6" out there in the panhandle west of Amarillo, busy night for them I'm sure.

[Brent]

[1900hurricane]

There will be big issues if the 00Z 4 km NAM comes anywhere close to verifying

[vbhoutex]

Latest from Jeff Lindner: Looks like a very wet weekend for much of Texas!!

Extended period of unsettled weather heading for Texas.

Interesting feature has developed over the western Gulf of Mexico this afternoon with numerous thunderstorms. While models suggest a surge of deeper moisture, visible satellite images indicate a weakly defined rotation to the cloud pattern suggesting possibly a mid level disturbance that may have ejected out of the Bay of Campeche. Numerous thunderstorms accompany this feature as it is approaching the TX coast from the SE. Meso scale models are not really picking up on this feature…maybe the 4km WRF-NMM, but the TX Tech model does not see it. WRF-NMM really hammers our SW counties late tonight and much of the day tomorrow with excessive rainfall and extrapolation of the “vort” over the western Gulf would fall in line with that thinking while much of the rest of the guidance keeps things more on the scattered side. Will need to keep an eye on radar trends as this feature moves toward the coast.

Upper level storm system over the SW US will combine with TS Patricia off the west Mexico coast to produce a prolonged rainfall event over much of Texas from Thursday into Tuesday of next week.

Friday:

Upper level dynamics will move into western and central TX while rich tropical moisture from the Bay of Campeche lifts northward into TX. A batch of dry air over the SE US may move into SE TX on Friday keeping the highest rain chances aimed at the coastal bend into central and north TX. Friday will also feature the landfall of Hurricane Patricia on the west coast of Mexico and its associated moisture starting to lift northward over central Mexico

Weekend:

Upper trough edges closer to TX while mid and high level moisture and upper level vort from Patricia lifts NNE into TX. Expect numerous thunderstorms to develop from Saturday afternoon through Sunday night with potential for periods of sustained cell training in south to north bands. PWS surge to 2.3-2.5 inches (+2 SD above normal for late Oct). Lift will be sustained from the upper level trough and Patricia “vort” along with developing coastal trough. Weak frontal boundary comes into play on Sunday and only helps to enhance the heavy rainfall threat. As it that is not enough…models are attempting to develop a coastal low either on the weak front or as a surface reflection of the upper level remains of Patricia (this would be similar to a decaying Gulf of Mexico hurricane forming a surface reflection days later off the US east coast). The GFS and ECWMF models want to then linger this system off the TX coast into the middle of next week which would only keep rain chances going longer into next week.

Rainfall Amounts:

Models continue to advertise heavy totals of anywhere from 5-15 inches over the next 5-days over portions of the state. Two main areas are starting to indicate enhanced potential.

1) N TX into SE OK

2) TX coastal bend into SC TX and the SW/W portions of SE TX

While these two areas appear the current primed target for the maximum rainfall…these areas have been shifting around some and the overall pattern will support excessive rainfall over a large portion of TX so I would not put much confidence in the exact areas of heavy rainfall at this time.

One interesting aspect that does continue to show up in many of the models is a wedge of dry air that seems to not want to dislodge over EC TX into portions of SE TX and this continues to cut back rainfall amounts from Houston northeastward. This appears to be a function of the alignment of the surface high and recirculation of dry air over the SE US based on 850mb wind trajectories. Such trajectories show the air mass flowing into the coastal bend originating in the Caribbean Sea while that flow into areas east of I-45 are originating in a much drier air mass off the SC coast. At some point the moisture from Patricia will likely overcome this dry air surge…but this could lead to vast rainfall total differences over SE TX.

Will go with widespread 3-5 inches west of I-45 and 2-4 inches E of I-45. Isolated locations could easily see 10 inches especially the Matagorda Bay region up toward College Station.

While grounds are very dry, widespread significant rainfall is certainly going to produce run-off at some point. Flash Flood guidance is around 5-6 inches for all of our counties, but gradual saturation of the soil layer is expected over time. Wildcard may end up being just where and how much rain falls tomorrow from the “vort” approaching the TX coast this afternoon as this could lead to early ground saturation and much more significant run-off during the weekend period.

Tides:

Continue to have issues at high tide on Bolivar with overwash of HWY 87 just west of HWY 124. Tides continue to run 1-2 ft above normal and see no reason that is going to change into the weekend with sustained 15-25mph onshore winds. Tides on the west side of Galveston and Matagorda Bays have been averaging around 3.0 ft total water level which is about 1-1.5 ft below coastal flood warning criteria. Do not think we will reach warning criteria over the next several days…but a coastal flood advisory will remain in effect since some minor overwash is already occurring with current levels.

Tides Sunday into Monday will depend on what if anything transpires off the coast with respect to any sort of non-tropical surface low formation. Such a feature if it were to develop would certainly increase winds and seas and given already higher than normal tides, if would not take much to push water levels above critical flood thresholds.



Summary of Changes:

· Potential for heavy rains tonight/Thursday around Matagorda Bay and southwest counties

· Delayed onset of heavy rainfall event from Friday to Saturday over SE TX with arrival of remains of TC Patricia

· Extend duration of the event into Monday, possibly Tuesday



Highlights:

· Heaviest rainfall likely west of I-45

· Some flooding will be possible over the weekend especially Sunday

· Rises on area rivers possible early next week

· Coastal tides will remain 1-2 ft above normal with some overwash on Bolivar at high tide

[Brent]

There will be big issues if the 00Z 4 km NAM comes anywhere close to verifying

Does that say 17 inches?

and that's before the 2nd round on Saturday...

[vbhoutex]

The more I see from different sources and different Professional Mets the more concerned I am about the upcoming rains in Texas. It appears that several areas of the state may have excessive flooding rains. PLEASE STAY TUNED TO YOUR LOCAL WEATHER SOURCES AND BE PREPARED. If your area does have heavy rains and flooding remember TURN AROUND DON'T DROWN!!

[Ntxw]

Yeah we are starting to get into hi res short range guidance. The foot+ of rain shifts around model to model run to run. We should have a better idea here soon with short range models.

Hopefully all Texans stay safe in this.

From extreme drought, to flash flood, to flash drought, back to flash flood. Only in Texas. What a wild year 2015 is.

[JayDT]

Are the models still showing the DFW area in the area of heaviest rainfall totals?

[cheezyWXguy]

Are the models still showing the DFW area in the area of heaviest rainfall totals?

Yes, but the heaviest rain totals are shifting to different areas across the metro with each run. 12z GFS had the band of rain bisecting the metro from SW-NE, while the 12z Euro had it about a county SE of there. The NAM is further west, as is the 18z GFS i believe. It's likely to continue fluctuating over the next few runs until the event actually starts, but hopefully things continue to get more consistent over the next 24 hours.

[JayDT]

Are the models still showing the DFW area in the area of heaviest rainfall totals?

Yes, but the heaviest rain totals are shifting to different areas across the metro with each run. 12z GFS had the band of rain bisecting the metro from SW-NE, while the 12z Euro had it about a county SE of there. The NAM is further west, as is the 18z GFS i believe. It's likely to continue fluctuating over the next few runs until the event actually starts, but hopefully things continue to get more consistent over the next 24 hours.

Thank for the reply. Wow, well yea hopefully we do get some consistency soon. Either way it seems like we're going to get plenty of rain which is awesome.

[Brent]

Are the models still showing the DFW area in the area of heaviest rainfall totals?

Yes, but the heaviest rain totals are shifting to different areas across the metro with each run. 12z GFS had the band of rain bisecting the metro from SW-NE, while the 12z Euro had it about a county SE of there. The NAM is further west, as is the 18z GFS i believe. It's likely to continue fluctuating over the next few runs until the event actually starts, but hopefully things continue to get more consistent over the next 24 hours.

Thank for the reply. Wow, well yea hopefully we do get some consistency soon. Either way it seems like we're going to get plenty of rain which is awesome.

I'm pretty much still just expecting a general solid 2-5" rainfall(which would still be amazing considering how dry it's been) with the full disclosure that some people will get a lot more. Whether it's east of the metro, over the metro, west of the metro, south of the metro, etc, we'll just have to see.