July 2021

General Weather Discussions and Analysis
davidiowx
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Core rains will be well out of the CWA. However, in layman’s terms, tropical rains like this can accumulate very fast. Even if the radar is only showing green in lieu of yellow/red, PWVs are high. Just a basic, and I’m most cases irrelevant, green band with a hint of yellow, can quickly drop several inches.
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don
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Stratton20 wrote: Thu Jul 08, 2021 7:26 pm Don but wouldnt that light rain over the gulf help to stabilize the atmosphere?
Warm core lows don't need a lot of instability. As they feed off of the heat from.the day once it goes back into the atmosphere at night. The strong low level jet will also help to enhance moisture as it increases tonight. The HRRR is showing preciptable waters later tonight as high as 2.75+ inches.
Dls2010r
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I spoke too soon…. Raining here now but not heavy.
Stratton20
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Don jeez 2.75 inches? Thats like a fire hose😬😬
TexasBreeze
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Looks like an all night soaker to me. The band is getting heavier and it is slow moving too.
davidiowx
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Radar looking like rain is a comin’
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djmike
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Rain shield is shrinking just as fast as it grew and filled in. That lasted a whole hour of sprinkles.
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(IH-10 & College Street)
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Rip76
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djmike wrote: Thu Jul 08, 2021 9:04 pm Rain shield is shrinking just as fast as it grew and filled in. That lasted a whole hour of sprinkles.
Yeah, poof
Stratton20
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Yup I expect we are going to start seeing counties being removed from the FFW soon
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DoctorMu
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Ptarmigan wrote: Thu Jul 08, 2021 7:28 pm
DoctorMu wrote: Thu Jul 08, 2021 7:08 pm The atmosphere had a very sub-tropical look this afternoon. Having lived in Florida and North Carolina, it was cool to see that kind of air again.

The "Outer bands" arrived not quite an hour ago. Good thing I finished mowing. Remarkable stretch of weather for July in the Brazos Valley...and it goes on and on.

Tonight could be a real nocturnal soaker.
Looks like a core rain event. They occur with warm core lows and the thunderstorms tend form near the center at night. Examples of core rain are Harvey, Allison, Claudette, Amelia, and 1921 Thrall Flood.
The rain shield is backing away and remaining south of Hwy 10unmentionable.

Watch the area near Victoria. It could blow up later tonight.
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DoctorMu
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The models that predicted the major action would be SW of HGX are proving correct. we'll see tonight.

Fingers crossed about a continued delayed return of the DR.


Area Forecast Discussion
National Weather Service Houston/Galveston TX
714 PM CDT Thu Jul 8 2021

.AVIATION [00Z TAF Issuance]...

With the messy wet forecast continuing into tonight, have tried to
best time the bands of SHRA (isolated TSRAs) through the overnight
period...all strongly influenced by the latest HRRR guidance. And,
with that being said, aviation interests should continue to expect
a slew of amendments as conditions change throughout the night. As
we head into tomorrow afternoon, the weakening upper low and upper
ridge trying to build back into the region from the W/NW should be
heralding the onset of a slightly drier pattern. 41

&&

.PREV DISCUSSION... /ISSUED 239 PM CDT Thu Jul 8 2021/

..Locally Heavy Rain Possible over Parts of SE TX...

SHORT TERM [Tonight Through Friday Night]...

A broad upper level low over South Texas and a weak surface low in
roughly the same area of South Texas and a weak coastal trough of
low pressure will focus periods of showers and thunderstorms near
the middle and upper Texas coast through Friday. The surface low
retreats to the southwest by early Friday but the position and
orientation of the upper level feature will keep SE TX in a
favorable region for additional rain. The low level jet (LLJ)
increases to 30-35 knots between 03-06z tonight and the nose of the
jet targets the area around Matagorda Bay so feel the heaviest rain
should develop across Matagorda, Jackson and Wharton counties.
SOme
of the models expand the precip into Harris but feel this is
overdone based on the orientation of the LLJ. The Flash Flood Watch
was expanded earlier to include Wharton and Ft Bend counties and
have some concern that Colorado county needs to be included as well.
Will advise the next shift and will monitor rainfall trends in that
area closely. Jet dynamics not looking as impressive as it did
yesterday but upper level winds still show a split across the region
but the speed max is no longer a significant player. As for rainfall
tonight, still looking for an additional 4 to 8 inches of rain in
the watch area with isolated totals between 10-12 inches. Further
north, 1 to 3 inches of rain possible over the central zones and
less than an inch over the northern zones.
Significant river
flooding will be possible over the Lavaca Navidad, Tres Palacios and
San Bernard watersheds.

On Friday, locally heavy rain will probably persist over much of the
area during the morning but the upper low and surface low both
retreat to the W-SW and moisture levels begin to drop with PW values
falling to around 2.00 inches by mid-afternoon. Forecast soundings
show some drying in the 850-700 mb layer as well. There should be a
decrease in precipitation during the afternoon with drier conditions
to the E-NE and wetter to the W-SW. Upper level ridging will try to
expand into SE TX Friday night, but moisture trapped beneath the
ridge should allow for some isolated to scattered showers to
persist.


Clouds and rain cooled air should keep MaxT values a little below
climo but overnight lows should remain near climo for the next
couple of days. 43

LONG TERM [Saturday Through Thursday]...

"Here comes the sun, do do do do!" Saturday will essentially be our
transition day from the widespread coastal rains associated with the
previous low pressure system in South Texas to diurnally driven
scattered afternoon showers and thunderstorms that interact with the
seabreeze. This is due to the moisture transport decreasing as the
low dissipates with PW values finally dropping below 2" over the
weekend. As moisture fades away throughout the day on Saturday,
locations north of I-10 will be able to see more blue skies than
gray skies. This will be temporary though...global models are still
in consensus on an upper-level low embedded in a longwave trough
digging down into the Central Plains on Sunday. A corresponding
surface low will form in the Upper Midwest and attempt to push a
surface cold front into Southeast Texas. I say attempt because...it
won`t quite make it (sorry y`all). The GFS still takes the front the
furthest south of all of the solutions into the Brazos Valley before
it washes out. Meanwhile, the ECMWF washes the front out to the
north of the CWA. The positioning of the front is a key factor into
the rain chances on Sunday/Monday. With the consistency of the
models in keeping the front mostly north of the CWA, higher PoPs
will be relegated over our northern counties due to increased
moisture convergence with PW values approaching 2" and more
favorable jet mechanics. For now, going with 50-60% PoPs Sunday
through Monday afternoon.


Following Monday, we return back to our regularly scheduled
programming of afternoon showers and thunderstorms. With the
decreasing coverage of rain, temperatures will be able to climb back
into the 90s. Fortunately, model trends still indicate that high
temperatures will remain slightly below normal through next week
with highs in the low 90s inland and upper 80s closer to the coast.
Looking further ahead, there are no strong signals of a return to
upper-level ridging, so the below normal high temperature trend
appears that it will continue into next weekend.
Overnight
temperatures will hold steady in the mid-to-upper 70s throughout
the forecast period, which is right around normal.

Batiste

HYDROLOGY...

Heavy rain is expected to develop tonight, especially over the SW
zones. If heavy rain does develop, there will likely be some
significant rises on the Lavaca Navidad, Tres Palacios, and San
Bernard watersheds. Based on current QPF forecasts, the Tres
Palacios could reach major flooding. Rainfall rates could reach 2-3
inches per hour with additional rainfall totals of 4 to 8 inches
possible in the Flash Flood Watch area. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 74 83 75 90 75 / 80 80 20 30 10
Houston (IAH) 74 82 76 90 76 / 90 80 40 50 10
Galveston (GLS) 78 84 82 89 80 / 90 70 40 50 20
Cromagnum
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1140 PM and the radar barely shows anything. I think this thing keeps rain where its least needed and completely away from our area.
Stratton20
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Well my kprc app has future track and its saying that things will start to fire up after 1 am, we will see if that comes to fruition or not
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don
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Heavy rain moving into the metro this morning. It's going to be a messy commute.
Cromagnum
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Got up to get a drink of water and see that heavy stuff is moving in around 6 AM. Glad I'm off today and not driving in it.
davidiowx
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Water all over the roads down in the Stafford area heading into work. Several side streets have standing water and it looks like its going to be raining for quite some time.
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don
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Flood Advisory
National Weather Service Houston/Galveston TX
631 AM CDT Fri Jul 9 2021

TXC039-071-157-201-339-091430-
/O.NEW.KHGX.FA.Y.0131.210709T1131Z-210709T1430Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Brazoria TX-Chambers TX-Fort Bend TX-Harris TX-Montgomery TX-
631 AM CDT Fri Jul 9 2021

The National Weather Service in League City has issued a

* Flood Advisory for...
North Central Brazoria County in southeastern Texas...
Western Chambers County in southeastern Texas...
Eastern Fort Bend County in southeastern Texas...
Harris County in southeastern Texas...
Southeastern Montgomery County in southeastern Texas...

* Until 930 AM CDT.

* At 631 AM CDT, Doppler radar and automated rain gauges indicated
heavy rain due to showers and thunderstorms. Minor flooding is
ongoing or expected to begin shortly in the advisory area. Between
1 and 1.5 inches of rain have fallen.

Some locations that will experience flooding include...
Pasadena, western Pearland, Sugar Land, Baytown, Missouri City,
Deer Park, Stafford, South Houston, Bellaire, West University
Place, Galena Park, Jacinto City, Hunters Creek Village, Bunker
Hill Village, Piney Point Village, Second Ward, Greater Eastwood,
Greater Third Ward, Greater Fifth Ward and Downtown Houston.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Flood Advisory means river or stream flows are elevated, or
ponding of water in urban or other areas is occurring or is imminent.

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

Excessive runoff from heavy rainfall will cause flooding of small
creeks and streams, urban areas, highways, streets and underpasses
as well as other drainage areas and low lying spots.
Cpv17
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Big bust down here in Wharton County so far. Woke up to maybe about 2” total since yesterday. Was expecting to wake up to at least triple that amount.
Kingwood36
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Cpv17 wrote: Fri Jul 09, 2021 9:02 am Big bust down here in Wharton County so far. Woke up to maybe about 2” total since yesterday. Was expecting to wake up to at least triple that amount.
I think this whole event was over hyped just a little bit
davidiowx
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Cpv17 wrote: Fri Jul 09, 2021 9:02 am Big bust down here in Wharton County so far. Woke up to maybe about 2” total since yesterday. Was expecting to wake up to at least triple that amount.
I think it is safe to say there is plenty more coming down there just based off of radar. Time will tell if that line continues to slowly move east as it trains over the same areas.

HRRR is not impressed though.
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