August 2016: Rain Chances Continue.

[Ptarmigan]

Live Coverage Of Flood
http://www.wbrz.com/pages/live-stream-3/

[unome]

insane rain totals...

WPC Storm Summary for the Southeastern U.S. and Gulf Coast Heavy Rainfall.
Last Updated: 1120 AM EDT FRI AUG 12 2016

http://www.wpc.ncep.noaa.gov/discussions/nfdscc2.html

THE NEXT STORM SUMMARY WILL BE ISSUED BY THE WEATHER PREDICTION CENTER AT 400 PM CDT. PLEASE REFER TO YOUR LOCAL NATIONAL WEATHER SERVICE OFFICE FOR ADDITIONAL INFORMATION ON THIS EVENT.

[Ptarmigan]

You have to remember that the actual air temperatures back in 1962 were in the 112F to 115F range on this date across SE Texas. Let that sink in for a minute. Many of us didn't have Air Conditioning at that time. Just those hot attic fans circulating the steamy air throughout the house.

The highest temperature in 1962 was on August 9, which reached 106°F at Houston Weather Bureau Office. Of course Houston was less developed back than. If that happened today, I suspect the air temperature would be much higher, likely around 110°F to 115°F.

There is also a high of 108°F on August 18, 1909. Back than, Houston was way less developed like today or in 1962. I suspect if that happened today, the high could be easily 115°F.

August Records
http://www.srh.noaa.gov/hgx/?n=climate_iah_normals_aug

[davidiowx]

You have to remember that the actual air temperatures back in 1962 were in the 112F to 115F range on this date across SE Texas. Let that sink in for a minute. Many of us didn't have Air Conditioning at that time. Just those hot attic fans circulating the steamy air throughout the house.

The highest temperature in 1962 was on August 9, which reached 106°F at Houston Weather Bureau Office. Of course Houston was less developed back than. If that happened today, I suspect the air temperature would be much higher, likely around 110°F to 115°F.

There is also a high of 108°F on August 18, 1909. Back than, Houston was way less developed like today or in 1962. I suspect if that happened today, the high could be easily 115°F.

August Records
http://www.srh.noaa.gov/hgx/?n=climate_iah_normals_aug

Gotta love June 5th and 6th back in 2011. Sheesh what a summer that was.

And that 106 on August 11 of last year as well.

[Ounce]

By looking at some of the models posted by Srain, et al, that this Low pressure would probably never get west of Houston, so we wouldn't be getting the dirty side of the low, hence gobs of rain like what Louisiana is experiencing. Is that somewhat accurate?

Granted, we should get some rain, but not the 9" forecast in central La. Thanks.

[A.V.]

The highest temperature in 1962 was on August 9, which reached 106°F at Houston Weather Bureau Office. Of course Houston was less developed back than. If that happened today, I suspect the air temperature would be much higher, likely around 110°F to 115°F.

There is also a high of 108°F on August 18, 1909. Back than, Houston was way less developed like today or in 1962. I suspect if that happened today, the high could be easily 115°F.

August Records
http://www.srh.noaa.gov/hgx/?n=climate_iah_normals_aug

Austin's record high is 112F. Thus, 115F for Houston, even with UHI, is quite overdone.

[Ptarmigan]

The highest temperature in 1962 was on August 9, which reached 106°F at Houston Weather Bureau Office. Of course Houston was less developed back than. If that happened today, I suspect the air temperature would be much higher, likely around 110°F to 115°F.

There is also a high of 108°F on August 18, 1909. Back than, Houston was way less developed like today or in 1962. I suspect if that happened today, the high could be easily 115°F.

August Records
http://www.srh.noaa.gov/hgx/?n=climate_iah_normals_aug

Austin's record high is 112F. Thus, 115F for Houston, even with UHI, is quite overdone.

The urban heat island increases temperatures by 5 degrees.

The 112°F record happened at Camp Mabry in 2000 and 2011.

There was 108°F on July 11, 1917, 109°F on July 26, 1954 at Camp Mabry.
http://threadex.rcc-acis.org

Since Austin is less humid, if those highs back than happened today, they could go well over 115°F, possibly even close to 120°F.

[srainhoutx]

Friday afternoon briefing from Jeff:

Tropical low over southern Louisiana to bring heavy rains back to SE TX this weekend.

Life threatening flash flood event continues to unfold across southern Louisiana where rainfall totals since 400am this morning have exceeded 15 inches in some locations. Surface low of 1009mb located inland north of Baton Rouge is drifting toward the west slowly with a large swath of very heavy rainfall on its SW flank extending westward to east of Lake Charles. It is certainly possible that some locations over southern Louisiana could approach 20-25 inches of rainfall in 48 hours with this system.

Upper level ridge over TX is in the process of breaking down and shifting WSW as a trough advances into the state from the NW this afternoon. Moisture from former TS Javier over the eastern Pacific is advecting NE along this trough/frontal boundary into NW TX where numerous showers and thunderstorms are starting to develop. Mid and surface low pressure system over southeast Louisiana will continues its slow drift westward this weekend and be located somewhere near/over SE TX by Sunday. Will see a marked increase in rain chances starting later on Saturday as rain bands approach from the ENE and pivot into the region. Subsidence from the ridge aloft will decrease and tropical moisture will surge into the region with PWS values over SW/SC Louisiana currently in the 2.5-2.8 inches range which is near maximum values for summer. Hence there is little surprise in the rainfall rates and amounts that have fallen over Louisiana today.

GFS maintains a very well defined 850mb vort center into SE TX Sunday and this would be very concerning as core rains will focus around this center while the ECMWF and other models are not as defined with the 850mb center and show a more elongated trough of low pressure moving in from the east. Given that the surface pressure has actually fallen to 1009mb today is interesting…almost like the surface center is intensifying even though it is inland…we have seen this before with decaying tropical systems close to the Gulf of Mexico which are able to feed off the very moist air mass and maintain their definition in defiance of land interaction. Not ready to jump on the GFS solution just yet which is showing some impressive totals over the region since there is little model support from the other major models. Will just have to watch how activity to our east unfolds over the next 24-36 hours and how defined the circulation remains. If other models begin to show what the GFS is showing then a significant increase in QPF will be required along with likely flash flood watches…a bit difficult to digest given KBDI values are 650-750 over many counties indicating very dry conditions.

Will go with widespread rainfall of 2-4 inches NE of a line from College Station to Katy to Galveston and 4-6 inches around Lake Livingston with lower amounts to the SW around Matagorda Bay which will be well removed from the track of this feature. With that said…we need to be aware that the SW flank of this system has been the active side and if this continues this may bring higher totals across a larger part of the area. Think these totals may be on the conservative side, but not enough confidence just yet to bump them up.

Onset of tropical air mass and saturated air column certainly will support very heavy rainfall rates of 2-4 inches per hour under the heavy rain cores which will quickly lead to rapid run-off even with generally dry grounds…it will just be raining too hard and fast to give the ground time to absorb much water. End result will likely be street flooding and flooding of underpasses…and now is a good time to remind residents not to drive into those high water locations…stated more bluntly if water is over the road do NOT drive into it!

Will see how things unfold over the next 24-48 hours before placing much stock into next week…but the overall pattern remains a wet one with no upper ridging returning and moisture values remaining high…will likely need at least 40-50% chances each day after Monday.

[A.V.]

The urban heat island increases temperatures by 5 degrees.

The 112°F record happened at Camp Mabry in 2000 and 2011.

There was 108°F on July 11, 1917, 109°F on July 26, 1954 at Camp Mabry.
http://threadex.rcc-acis.org

Since Austin is less humid, if those highs back than happened today, they could go well over 115°F, possibly even close to 120°F.

The effect of UHI is dependent of geographic/climate factors, as well as level of build. Houston Hobby is more built up, and is more in the center of the urban core compared to many areas of inland/northern Houston metro (College Station, Tomball, Woodland, etc), but, because it is in the sea-breeze zone, it has lower 100F frequency than those places.

[srainhoutx]

Today looking at the Climate Prediction Center updated Day 8 to 14 Outlook and the Day 11+ Analogs, it appears we are indeed seeing a significant pattern change and the hot days of summer may be slowly coming to an end.

[Skyguy]

.

Will just have to watch how activity to our east unfolds over the next 24-36 hours and how defined the circulation remains

.

Do you have any data on that, Srainhoutex? I can't call anybody out there right now, 'cause my cell phone keeps giving me the "no signal" message. Would appreciate your help.


BTW:

1.Where can I send an e-mail to Mario Gomez? I would like to wish him well in his retirement.

2. From this graphic It still looks to me like Houston will escape the worst of the rains. Do you agree, Srainhoutex?

[worrybug]

Dear pro mets:

These two items from the HGX AFD are a little beyond my personal comprehension.

719
FXUS64 KHGX 130025
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
725 PM CDT Fri Aug 12 2016

.AVIATION...
VFR conditions to continue overnight with a possibility of some
patchy MVFR ceilings around sunrise tomorrow morning. Winds
overnight will be southerly at 5 to 10 knots.

Showers and thunderstorms will gradually increase in coverage
during the day on Saturday. Isolated showers late Saturday morning
will become scattered to numerous showers and thunderstorms by
late afternoon. The heaviest precipitation will move in to SETX
airspace from the east with conditions worsening after 21Z. I
addressed the afternoon precipitation with a VCTS in this TAF
package, however I am considering a PROB30 after 21Z tomorrow for
the 06Z TAF package. Keehn/44

&&

.PREV DISCUSSION... /ISSUED 410 PM CDT Fri Aug 12 2016/

DISCUSSION...
A heat advisory remains in effect for all of SE TX until 7 PM this
afternoon. The forecast gets tricky heading into tomorrow as a
front begins its approach from the northwest and a disturbance
currently hammering Louisiana begins to shift westward. Showers
and thunderstorms should start to get going during the day
Saturday, but the main event should occur in the Saturday night
through Sunday night time frame. WPC currently has much of SE TX in
a slight risk for excessive rainfall both Saturday and Sunday.
Current thinking is for around 3 to 5 inches of QPF through early
Monday, primarily over the northern and eastern areas. However,
isolated totals of up to 10 inches cannot be ruled out. We have
been discussing the possibility of a Flash Flood Watch for
Saturday Night through Sunday Night but have decided to hold off
for now.

Note I have put the statements I don't understand in bold.

1. What do they mean by "conditions worsening?" What kind of conditions are they looking for? TC-like?

2. Notice the forecaster identified the main area of concern as the

northern and eastern areas

. I live in southwest Houston, south of I-10. Is my risk of severe weather less than those locations just mentioned.

Get back with me as soon as you can.

[worrybug]

Dear pro mets:

These two items from the HGX AFD are a little beyond my personal comprehension.

719
FXUS64 KHGX 130025
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
725 PM CDT Fri Aug 12 2016

.AVIATION...
VFR conditions to continue overnight with a possibility of some
patchy MVFR ceilings around sunrise tomorrow morning. Winds
overnight will be southerly at 5 to 10 knots.

Showers and thunderstorms will gradually increase in coverage
during the day on Saturday. Isolated showers late Saturday morning
will become scattered to numerous showers and thunderstorms by
late afternoon. The heaviest precipitation will move in to SETX
airspace from the east with conditions worsening after 21Z. I
addressed the afternoon precipitation with a VCTS in this TAF
package, however I am considering a PROB30 after 21Z tomorrow for
the 06Z TAF package. Keehn/44

&&

.PREV DISCUSSION... /ISSUED 410 PM CDT Fri Aug 12 2016/

DISCUSSION...
A heat advisory remains in effect for all of SE TX until 7 PM this
afternoon. The forecast gets tricky heading into tomorrow as a
front begins its approach from the northwest and a disturbance
currently hammering Louisiana begins to shift westward. Showers
and thunderstorms should start to get going during the day
Saturday, but the main event should occur in the Saturday night
through Sunday night time frame. WPC currently has much of SE TX in
a slight risk for excessive rainfall both Saturday and Sunday.
Current thinking is for around 3 to 5 inches of QPF through early
Monday, primarily over the northern and eastern areas. However,
isolated totals of up to 10 inches cannot be ruled out. We have
been discussing the possibility of a Flash Flood Watch for
Saturday Night through Sunday Night but have decided to hold off
for now.

Note I have put the statements I don't understand in bold.

1. What do they mean by "conditions worsening?" What kind of conditions are they looking for? TC-like?

2. Notice the forecaster identified the main area of concern as the

northern and eastern areas

. I live in southwest Houston, south of I-10. Is my risk of severe weather less than those locations just mentioned.

Get back with me as soon as you can.

[Skyguy]

Dear pro mets:

These two items from the HGX AFD are a little beyond my personal comprehension.

719
FXUS64 KHGX 130025
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
725 PM CDT Fri Aug 12 2016

.AVIATION...
VFR conditions to continue overnight with a possibility of some
patchy MVFR ceilings around sunrise tomorrow morning. Winds
overnight will be southerly at 5 to 10 knots.

Showers and thunderstorms will gradually increase in coverage
during the day on Saturday. Isolated showers late Saturday morning
will become scattered to numerous showers and thunderstorms by
late afternoon. The heaviest precipitation will move in to SETX
airspace from the east with conditions worsening after 21Z. I
addressed the afternoon precipitation with a VCTS in this TAF
package, however I am considering a PROB30 after 21Z tomorrow for
the 06Z TAF package. Keehn/44

&&

.PREV DISCUSSION... /ISSUED 410 PM CDT Fri Aug 12 2016/

DISCUSSION...
A heat advisory remains in effect for all of SE TX until 7 PM this
afternoon. The forecast gets tricky heading into tomorrow as a
front begins its approach from the northwest and a disturbance
currently hammering Louisiana begins to shift westward. Showers
and thunderstorms should start to get going during the day
Saturday, but the main event should occur in the Saturday night
through Sunday night time frame. WPC currently has much of SE TX in
a slight risk for excessive rainfall both Saturday and Sunday.
Current thinking is for around 3 to 5 inches of QPF through early
Monday, primarily over the northern and eastern areas. However,
isolated totals of up to 10 inches cannot be ruled out. We have
been discussing the possibility of a Flash Flood Watch for
Saturday Night through Sunday Night but have decided to hold off
for now.

Note I have put the statements I don't understand in bold.

1. What do they mean by "conditions worsening?" What kind of conditions are they looking for? TC-like?

2. Notice the forecaster identified the main area of concern as the

northern and eastern areas

. I live in southwest Houston, south of I-10. Is my risk of severe weather less than those locations just mentioned.

Get back with me as soon as you can.

Well, I can' really answer either question for you, Mr. Worrybug. But I do have a little tidbit from Beaumont's AFD that kinda parallels what HGX has been saying:

We are monitoring our southeast Texas area for a Flash Flood Watch which may be needed as early as Saturday morning if the westward trend of heavy rain continues and forecasted QPF values increase. However. StormTotal QPF currently does not support the issuance of the FFA at this time for southeast Texas as 3.5 to 3.75 inches of rain is forecasted through Sunday morning over the much drier soil

Could somebody help out Mr. Worrybug, please?

[TexasBreeze]

http://radar.weather.gov/Conus/southpla ... e_loop.php

I see this event being more beneficial for dry Texas more than anything. The moisture around the low to the east looks to be colliding with the moisture from the southward moving cold front to the northwest. Could make for a wetter day Saturday earlier.

[StormOne]

1. What do they mean by "conditions worsening?" What kind of conditions are they looking for? TC-like?

Not TC like. They mean an increase in rain and storm coverage.

I live in southwest Houston, south of I-10. Is my risk of severe weather less than those locations just mentioned.

What they were saying here is that, for now, the highest areas of precipitation seems to be in the Northern and Eastern areas. However, things are changing constantly, so that could very well change. Regardless, everyone can and will see rain from this, heavy at times.

[worrybug]

1. What do they mean by "conditions worsening?" What kind of conditions are they looking for? TC-like?

Not TC like. They mean an increase in rain and storm coverage.

I live in southwest Houston, south of I-10. Is my risk of severe weather less than those locations just mentioned.

What they were saying here is that, for now, the highest areas of precipitation seems to be in the Northern and Eastern areas. However, things are changing constantly, so that could very well change. Regardless, everyone can and will see rain from this, heavy at times.

Is this any different from the April 18th rain event? (I'll assume you know what I'm talking about, so I can help you maintain family friendliness.)

[Skyguy]

1. What do they mean by "conditions worsening?" What kind of conditions are they looking for? TC-like?

Not TC like. They mean an increase in rain and storm coverage.

I live in southwest Houston, south of I-10. Is my risk of severe weather less than those locations just mentioned.

What they were saying here is that, for now, the highest areas of precipitation seems to be in the Northern and Eastern areas. However, things are changing constantly, so that could very well change. Regardless, everyone can and will see rain from this, heavy at times.

Is this any different from the April 18th rain event? (I'll assume you know what I'm talking about, so I can help you maintain family friendliness.)

This from Brooks Garner on Facebook:

Nearly a foot of rain flooded huge portions of Louisiana last night and indications suggest Houston could be in line for a piece of this heavy rain Saturday evening, night and Sunday morning. Head's-up if you have any plans. Flooding potential certainly exists... This thing closely resembles an inland tropical depression. The heaviest rain will most likely occur just east of the Houston metro, but we will tap some of that deep tropical moisture, resulting in less prolonged, but comparably heavy downpours this weekend.

I think some people will have problems, but, like Brooks said, it all depends on how far west this thing moves. FWIW, given the superficial resemblance to a tropical system, it could easily make a sudden turn to the E/NE and the heavy rains miss Houston altogether.

[houstonia]

9:11 pm update:
000
FXUS64 KHGX 130211
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
911 PM CDT Fri Aug 12 2016

.DISCUSSION...
The deep layer low was located over Louisiana this evening. By 9
PM, showers and isolated thunderstorms were approaching the far
northern set of counties from the north. Very dry air was still
over the southern portions of the forecast area. This can be seen
on the 00Z soundings -- CRP had a PW of 1.31 while LCH had a PW of
2.46. This is in line with the the latest model runs which were
still showing the best chances on Saturday.

Tweaked the isolated chances a bit further to the south to account
for the current coverage.

[Ounce]

Bug,
Recommend letting time pass until mid-Saturday afternoon and see how things are shaking out, plus re-read what Brooks wrote.