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2019 Rain Thread


Biff Tannen

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Euro models are notorious for kicking the American model's ass.  But the Euro computer system is like 2X the size and power of the Americans.  The best in the world is the European model (ECMWF), located in England but run/supported by over 20 Euro countries , followed by  the United Kingdom Met Office. However, the Yanks just installed a new computer, the  FV3 Dynamic Core, which probably puts the Americans up to #3 from #4 in the world (the reason you don't see many weather guys quoting he UK Met Office model is that its less public than the others and is mostly used in-house, so it's difficult to get stuff from it). The FV3 has improved the American forecasting since it was launched in early March, of course results are still kinda new, but it's not going to be a giant leap into first place like you might think.  It's better though.

The thing is, the Euro and American model systems use vastly different methods for calculating/forecasting, and of course both models work together and are seen as compliments rather than combatants.  The Euro system though is a lot more expensive and vast... the U.S. really isn't going to spend that kind of bucks for a super-duper thing, especially since the Euro is there and is easily available.  Still, we can now say "We're Number 3!!!" with confidence.

The rain totals within a given forecast area have actually been pretty accurate over the last 2-3 years especially.  While your little neck of the woods was forecast to have 4 inches and you got very little, the models didn't necessarily fail at all.. the rain simply fell somewhere else within the forecast area.  Right now the areas usually average about 200X200 miles or so, so it's not pinpoint.  In the series of recent storms, the Euro model has been pretty damn accurate actually, with the GFS slightly behind.

The forecasting of precip totals say within a 50 square mile area (i.e. about 2/3 the size of Austin city proper) is nowhere near realized yet technologically, and likely won't be for some time.  To predict within a few towns over how much/where the rain is going to fall is extremely difficult.  It's like you're trying to predict when two drag racers hit the gas without a Christmas Tree to time them.  Conditions over very small areas, over a small space of time (say within 8 hours) are simply too random to nail, at least with today's technology.
 

But all in all, the models are doing a lot better at getting more and more narrow and time-specific than even 5 years ago.  I'm kind of impressed with how well the models do now within 2 days of an event.

Saturday forecast coming... looks like another brief but powerful rain event... could flood... later today or early tomorrow I'll be back.

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23 hours ago, phdhorn said:

Euro models are notorious for kicking the American model's ass.  But the Euro computer system is like 2X the size and power of the Americans.  The best in the world is the European model (ECMWF), located in England but run/supported by over 20 Euro countries , followed by  the United Kingdom Met Office. However, the Yanks just installed a new computer, the  FV3 Dynamic Core, which probably puts the Americans up to #3 from #4 in the world (the reason you don't see many weather guys quoting he UK Met Office model is that its less public than the others and is mostly used in-house, so it's difficult to get stuff from it). The FV3 has improved the American forecasting since it was launched in early March, of course results are still kinda new, but it's not going to be a giant leap into first place like you might think.  It's better though.

The thing is, the Euro and American model systems use vastly different methods for calculating/forecasting, and of course both models work together and are seen as compliments rather than combatants.  The Euro system though is a lot more expensive and vast... the U.S. really isn't going to spend that kind of bucks for a super-duper thing, especially since the Euro is there and is easily available.  Still, we can now say "We're Number 3!!!" with confidence.

The rain totals within a given forecast area have actually been pretty accurate over the last 2-3 years especially.  While your little neck of the woods was forecast to have 4 inches and you got very little, the models didn't necessarily fail at all.. the rain simply fell somewhere else within the forecast area.  Right now the areas usually average about 200X200 miles or so, so it's not pinpoint.  In the series of recent storms, the Euro model has been pretty damn accurate actually, with the GFS slightly behind.

The forecasting of precip totals say within a 50 square mile area (i.e. about 2/3 the size of Austin city proper) is nowhere near realized yet technologically, and likely won't be for some time.  To predict within a few towns over how much/where the rain is going to fall is extremely difficult.  It's like you're trying to predict when two drag racers hit the gas without a Christmas Tree to time them.  Conditions over very small areas, over a small space of time (say within 8 hours) are simply too random to nail, at least with today's technology.
 

But all in all, the models are doing a lot better at getting more and more narrow and time-specific than even 5 years ago.  I'm kind of impressed with how well the models do now within 2 days of an event.

Saturday forecast coming... looks like another brief but powerful rain event... could flood... later today or early tomorrow I'll be back.

TL;DR...we gettin' fucked or what? 

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On 5/15/2019 at 7:19 AM, Armybrat said:

TV weather guys always yapping about their computer models (GFS, Euro) for predicted rainfall totals. Has anyone actually done a study to see which one has been more accurate for the Central Texas area?

The GFS (Garbage Forecasting System) is worthless.   

I don't know how many times in the winter the model suggest we are going to have cold weather and record breaking  at that and ends up being wrong in big fashion.

Too many of the newer Mets rely on computers instead of good ol fashion historical data.  

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11 minutes ago, Nueces River Rat said:

Too many of the newer Mets rely on computers instead of good ol fashion historical data.  

I had to laugh when I saw that channel 5 here promoted one of the long time traffic girls to "meteorologist."  I mean, I don't mind a little eye candy, although this one is a little skinny/anorexic for me, but I doubt she has any training in weather.

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22 minutes ago, miguelito said:

I had to laugh when I saw that channel 5 here promoted one of the long time traffic girls to "meteorologist."  I mean, I don't mind a little eye candy, although this one is a little skinny/anorexic for me, but I doubt she has any training in weather.

Like some of the weather gals on Spanish language TV?     Yea I'm sure some of the "enhancements" are meant to allow the viewer to focus in on the high and low pressure systems on the map.

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8 hours ago, miguelito said:

I had to laugh when I saw that channel 5 here promoted one of the long time traffic girls to "meteorologist."  I mean, I don't mind a little eye candy, although this one is a little skinny/anorexic for me, but I doubt she has any training in weather.

 

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8 hours ago, miguelito said:

I had to laugh when I saw that channel 5 here promoted one of the long time traffic girls to "meteorologist."  I mean, I don't mind a little eye candy, although this one is a little skinny/anorexic for me, but I doubt she has any training in weather.

Anything that gets Niku more air time is alright by me.

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Update:
Models now moving the worst of it kinda north.  Could be changing the forecast.  We just might get out of this thing alive (what movie/where is that a quote (or near-quote from?).

Better forecast tomorrow morning.

fhd995A13_Xander_Berkeley_004.jpg

Then - We'll know.

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Let's Go With This:
It's pretty clear that the worst of this stuff is now forecast to be going to be NE of us, into the area N. of Williamson County, into DFW and up into NE Texas.  This low is now forecast to skirt more north than originally, so we'll be farther away from most of the lingering severe threats.

That said, this is a classic spring setup for us... a storm tracks north of us, but it builds a tail (line of storms), often which is severe.  The only question now is how far south that tail builds.  Most models put us right smack on the 50/50 area (i.e. 50% chance the worst of it will pass by to the north) - great (i.e. just lovely if you're trying to figure out wtf is gonna happen).  There is a pretty strong layer of mid-level warm air in South Central Texas today and tomorrow that might inhibit big storm production.  It just depends on how much that warm air gets beat up.  So:

- if this happens, we'll get an episode or two (mostly in a line) of heavy rain sweeping by but hardly anything, maybe half an inch, no severe.
- If this doesn't happen, (i.e. if the tail builds south to us), we'll get a line of strong with severe in spots storms coming by about mid-day Saturday.  This could include areas of high winds, hail quarter sized to tennis ball sized, and brief but heavy rain.

So which is it?  I've seen the line build south more than not in these situations, so I'm thinking there will be a period from late morning to early afternoon where a line, strong in some areas but not too severe, will sweep buy with maybe 15 minutes of heavy rain in most spots, but again, maybe putting down 2" in isolated spots, mostly an inch or less for most of us.  Line outta here by 3-4 p.m.  Not a total washout, but a 2-3 hour period of rain.  Still, not the "uh-oh" thing forecast earlier in the week.

The NWS has lowered our rain predictions a lot... maybe an inch in most spots, and this is from the line that'll sweep through Saturday.  I think this holds out.

tl;dr:  Rain, isloated strong storms, mostly a good thunderstorm or two, passes through ATX on 1-2 hours side of lunchtime Saturday, the more north you go the worse the storms are, a good sweep of rain but generally not enough to flood/completely wash out, clearing out by dinner, Sunday nice.  That's my story and I'm stickin' to it right now.


 

Edited by phdhorn
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38 minutes ago, Updawg said:

So is my daughters swim meet getting cancelled in 78749

Nope.  Plan on getting your ass up at 5am and getting out on deck!!!  It will start to rain at about 9a, they will wait 1 hr to see what is going to happen, and THEN it will be cancelled.  

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1 hour ago, Nonbryan said:

Nope.  Plan on getting your ass up at 5am and getting out on deck!!!  It will start to rain at about 9a, they will wait 1 hr to see what is going to happen, and THEN it will be cancelled.  

I see Austin uses the same sports methodology as Houston

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51 minutes ago, jimmyjazz said:

Don't forget, all sporting events get delayed 30 minutes following any lightning strikes within a 200 mile radius.

This.

And I forgot to mention that by the time they cancel the meet, your kids will be on FULL BLAST after they have eaten 2 donuts, 1 bottle of orange juice, 1 bag of skittles, a ring pop, and 3 pieces of gum.  Then you get to take them home to be stuck inside while it is raining!  Enjoy.  I know I will.

Everyone grab your pitchforks, this is PhD's fault!

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2 minutes ago, Nonbryan said:

And I forgot to mention that by the time they cancel the meet, your kids will be on FULL BLAST after they have eaten 2 donuts, 1 bottle of orange juice, 1 bag of skittles, a ring pop, and 3 pieces of gum.  Then you get to take them home to be stuck inside while it is raining!  Enjoy.  I know I will.

I remember those days.  My son (15) now plays on a pretty good select soccer team with an experienced coach and he is a tyrant about gameday nutrition.  When they're younger, half the kids are only there for the snacks.

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what about inks lake state park area this weekend?  boy scouts are camping there, my son's first camping without dad, and going caving on sunday?  rain I'm not worried about but Frankie talking about hail, big winds, tornado.  is Frankie full of shit @phdhorn?

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Convective development is initiating late this afternoon just to the
northwest of the CWA due to boundary layer de-stabilization and
orographic and dry line forcing. Isolated super cells could develop,
and there is a small chance of one or two of these discrete storms
reaching Val Verde county. Very steep mid level lapse rates, yielding
MLCAPE values in excess of 3000 J/kg, combined with deep layer shear
values of 30-40 kts will support a severe threat across western Val
Verde country through the evening, with large hail the primary
threat. A Severe Thunderstorm Watch has been issued through 11PM to
cover Val Verde County.

An upper level trough will lift out of the Rockies and into the
Plains overnight and Saturday. Round two begins overnight with storms
initiating to the northwest of the CWA. Many global and convective
allowing models allow a complex of storms to develop across the SJT
CWA. This complex could reach portions of the northern Hill Country
and southern Edwards Plateau during the early morning hours on
Saturday. The threat is expected to transition to more of a damaging
wind threat during this time. Farther east overnight, isolated
streamer showers may occur beneath the cap as 40kt low level jet
develops.

The convective forecast and severe potential beyond early Saturday
morning is highly conditional on the cap, as is often the case with
late Spring events where the main upper level support is to the north
of the area. 12Z BUFR forecast soundings from the NAM12 and GFS tell
the story, with the NAM12 partially eroding the cap across northern
areas of the CWA while maintaining the cap the further south and east
you go into the CWA. The could help explain why the NAM-3km quickly
decays the squall line midday Saturday as it reaches the I-35
corridor. GFS soundings are a little more optimistic with eroding
the cap farther south and east. A wide range of scenarios is depicted
by 12Z CAMs, with the ARW and NSSL WRF farther south with the
convective line, while the HRRR and Texas Tech WRF not showing much
of anything across the CWA.

Overall the PoP forecast will remain similar to the previous package,
showing the highest potential for the complex of storms reaching the
I-35 corridor across the northern CWA. We have included a severe
potential in the grids and zones to line up with SPC Day 2 convective
outlook. But again, this is all highly conditional on the cap mentioned
above. A severe threat will continue through the midday and into the
afternoon if the cap does erode, or forcing from the complex or line
segments is able to overcome the weaker portion of the cap. Damaging
winds and hail are the primary threats, although an isolated tornado
threat could occur across portions of the northeast CWA. Rainfall
amounts of 1/2 to 2 inches are forecast across the northern CWA and
less than 1/2 inch are forecast across southern areas of the CWA,
again cap conditional. There is a small threat isolated convection
could linger into Saturday night as the dry line remains retreats
slightly back to the west and the front never clears the area

This sounds like it is a lot of words to say, “It might rain. It might be severe. It might not rain. All of our fancy models disagree with each other. How the fuck do we know?”

Edited by Orange&White
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