June 2020

General Weather Discussions and Analysis
User avatar
Belmer
Global Moderator
Global Moderator
Posts: 685
Joined: Thu Jan 06, 2011 7:29 pm
Location: Katy, TX (I-10 & 99)
Contact:

Re: June 2020

Post by Belmer » Thu Jun 25, 2020 5:46 am

WPC.gif
WPC


Mesoscale Precipitation Discussion 0377
NWS Weather Prediction Center College Park MD
448 AM EDT Thu Jun 25 2020

Areas affected...Mid TX Coast into far southeast TX

Concerning...Heavy rainfall...Flash flooding possible

Valid 250900Z - 251300Z

SUMMARY...Storms training and backbuilding along a frontal
boundary in a high moisture environment could produce hourly
rainfall rates near 2.00 inches, resulting in flash flooding in
areas that saw heavy rainfall earlier this morning.

DISCUSSION...GOES-16 IR loop showed pulses of colder cloud tops
(with cloud top temperatures near -70 degrees C) with convection
along a frontal boundary extending from the Mid TX coast into
northwest LA. The storms continue develop on the northern edge of
a 2000/3000 J/KG MUCAPE gradient as they have for much of the
early morning hours.

Lift from a possible MCV associated with the earlier convection
north of KVCT may be providing enough mesoscale lift to allow the
storms to pulse in the mid level southwest flow. Low level
moisture convergence along the front is feeding the storms 2.00+
inch precipitable water air, which continues to result in hourly
rainfall rates of 2.00 inches across western Harris county, west
of downtown Houston.

Weak propagation vectors has resulted in storms training and
backbuilding across this area, which has produced 4.00/6.00 inches
of rainfall (based on the KHGX radar) over southern Colorado and
northern Wharton counties. As the MCV moves eastward, propagation
vectors could increase, which would result in less backbuilding,
but training along and and south of the front (along the
instability gradient) could continue through about 25/12z.

The most recent HRRR runs showed the potential for hourly rainfall
rates near 2.00 inches as the storms track east then northeast
along the front ahead of the MCV through 25/12z. After that time,
the storms weaken as the lift associated with the MCV weakens
across far southeast TX. Local 2.00/3.00 inch rainfall amounts are
possible where locally heavy rainfall occurred earlier this
morning.

Overall, the activity is expected to weaken with the lost of lift
and weakening low level convergence. Based on this, flash flooding
is considered possible through the early morning hours.
Blake
Boomer Sooner

Andrew
Site Admin
Site Admin
Posts: 3176
Joined: Wed Feb 03, 2010 9:46 pm
Location: North-West Houston
Contact:

Re: June 2020

Post by Andrew » Thu Jun 25, 2020 6:55 am

New line setting up over Houston but outflow boundary from the west should keep storms moving through. The flooding risk looks to be decreasing fortunately but we will need to monitor what happens overnight.
For Your Infinite Source For All Things Weather Visit Our Facebook

Cpv17
Posts: 1450
Joined: Fri Aug 31, 2018 12:58 pm
Location: El Campo/Wharton
Contact:

Re: June 2020

Post by Cpv17 » Thu Jun 25, 2020 7:18 am

Received another 2.15” overnight. Up to 5” total now the past two days. I’m satisfied.

txbear
Posts: 114
Joined: Wed Oct 31, 2018 11:54 am
Contact:

Re: June 2020

Post by txbear » Thu Jun 25, 2020 7:20 am

Andrew wrote:
Thu Jun 25, 2020 6:55 am
New line setting up over Houston but outflow boundary from the west should keep storms moving through. The flooding risk looks to be decreasing fortunately but we will need to monitor what happens overnight.
Yeah it was interesting to see the line that was entrained through Katy seemingly just "jump" down to the 59 corridor. Definitely shut things down, more or less, to the north of the new line.

Andrew, what is the thinking for the overnight hours? I'm guessing based on looking at the current surface map and models that the currently stationary front doesn't get anywhere fast and we have another round of redevelopment similar to last night/this morning. Location of the boundary again, will be key.

User avatar
tireman4
Global Moderator
Global Moderator
Posts: 2947
Joined: Wed Feb 03, 2010 9:24 pm
Location: Humble, Texas
Contact:

Re: June 2020

Post by tireman4 » Thu Jun 25, 2020 7:34 am

000
FXUS64 KHGX 251231
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
731 AM CDT Thu Jun 25 2020

.AVIATION...

Convection continues to develop along a weak boundary that extends
across the Houston terminals and KSGR. The boundary is progged to
become diffuse this morning and convection should begin to spread
out. Have included tempo groups for this morning as vsby/cigs will
drop in heavier rain. Will carry a VCSH/VCTS for this aftn. The
gradient will also tighten this aftn and have added gust groups
to most of the TAFs. VFR this evening with MVFR cigs developing
late. Another disturbance will move into the area after 06z and
SHRA/TSRA expected to redevelop. 43

&&

.PREV DISCUSSION... /ISSUED 417 AM CDT Thu Jun 25 2020/

SHORT TERM...(Today through Friday)

A nearly stationary boundary is draped across SE TX from the NE to
SW and convection has developed and remained anchored close to
this boundary. PW values are between 1.95 and 2.25 inches and
heavy rain has developed over parts of the area. Over 7 inches of
rain near Garwood overnight and up to 3 inches in SW Harris
county. The HiRes NMM and TT WRF initialized best and have leaned
toward their solutions this morning. Have added locally heavy rain
for this morning and extended the FFA to 15z. Convection should
begin to wane between 15-18z with more scattered activity expected
further west giving the rain soaked areas along the US 59 corridor
a chance to temporarily dry out. Clouds and precip should keep
MaxT under climo again today.

Tonight, another strong disturbance will move into the western
half of the CWA and provide for another chance of showers and
thunderstorms over mainly the western half of the CWA. With PW
values remaining at or above 2.00 inches, feel locally heavy rain
will remain a threat, mainly over the western half of the area.
Daytime heating and a weakness aloft will allow for scattered
showers and thunderstorms on Friday but PW values begin to drop
and coverage should be less than the past couple of days. 43

LONG TERM [Friday Night through Thursday]...

Although most of the heavy activity from the day is expected to be
decreasing Friday night, high moisture rates remain in place could
keep a few lingering showers and thunderstorms alive throughout the
night Friday. A weak upper level shortwave is expected to move
across TX Saturday and even though we may have Saharan dust (SAL)
filtering in from the Gulf of Mexico as well as lower PWs, unstable
air mass could result in some isolated to scattered activity for
Southeast Texas during the daytime. A similar weather pattern can be
expected Sunday as a surge of low level moisture from the Gulf moves
across the local area in the afternoon.

The local weather will gradually become a little more muted this
upcoming week in response to the sub-tropical ridge expanding into
TX. This will luckily be the dominant weather feature through mid
week, giving us a bit of a respite in the current ongoing heavy
rainfall. Note: Some of the models do show an upper level low/trough
moving into the Great Plains mid week which could retract the high a
bit west and south. If it does, this could increase our chances of
rain. The GFS is a bit more aggressive, keeping the low over the
Kansas, Nebraska, Missouri and Iowa area through the end of the work
week, while the EC is not as progressive and keeps us under a weak
area of high pressure. Due these inconsistencies, will stay
conservative with the PoPs (30% or less) for next week into the end
of the forecast period.

High temperatures will rise back into the low 90s this weekend in
response to lower cloud coverage and the lovely dust. Rising heights
next week will yield high temperatures in the mid 90s range. Heat
indicies will also be on the rise as well, reaching the low to mid
100s Monday through Thursday. 24

MARINE...

The pressure gradient will tighten today in response to deepening
low pressure in the lee of the Rockies. Onshore winds will
strengthen in response and a SCEC has been issued for the Gulf
waters and adjacent bays for today. The SCEC may need to be
extended tonight as moderate onshore winds persist. A moderate
onshore flow will persist through the weekend and SCECs will
likely be required into the weekend. The persistent onshore flow
will maintain slightly tides through Sunday with water levels near
3.0 feet at high tide through Sunday. Beachgoers should also
remain alert for rip currents as the long onshore fetch will
create rough surf on Gulf facing beaches. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 87 72 87 74 90 / 60 60 70 20 30
Houston (IAH) 86 76 86 76 90 / 70 50 50 20 40
Galveston (GLS) 86 81 86 80 87 / 70 40 30 20 30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flash Flood Watch until 10 AM CDT this morning for the following
zones: Austin...Colorado...Fort Bend...Inland Harris...
Waller...Wharton.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 7 PM CDT this evening
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.

&&

$$

Discussion...43
Aviation/Marine...43

User avatar
Belmer
Global Moderator
Global Moderator
Posts: 685
Joined: Thu Jan 06, 2011 7:29 pm
Location: Katy, TX (I-10 & 99)
Contact:

Re: June 2020

Post by Belmer » Thu Jun 25, 2020 7:41 am

Latest from the WPC:

Mesoscale Precipitation Discussion 0378
NWS Weather Prediction Center College Park MD
911 AM EDT Thu Jun 25 2020

Areas affected...Mid-Texas Coast to Far Southeast Texas

Concerning...Heavy rainfall...Flash flooding possible

Valid 251310Z - 251600Z

SUMMARY...Storms training and backbuilding along a frontal
boundary in a high moisture environment will continue to produce
area of hourly rainfall rates near 2.00 inches. This will result
in flash flooding, especially in areas that saw heavy rainfall
earlier this morning.

DISCUSSION...GOES-16 IR satellite imagery from around 1245Z showed
another round of cooling cloud tops (with cloud top temperatures
near -70 degrees C) along a frontal boundary extending from the
Mid TX coast into northwest LA. The storms continue develop on the
northern edge of a 2000/3000 J/KG MUCAPE gradient. This trend
looks to continue into the mid-morning before the models tend to
show weakening.

Propagation vectors remain weak, so a few spots still have the
potential to receive another 2 or 3 inches this morning either
from repeat convection or storms which build back across this
area. Concern for flash flooding is greatest where there is
overlap between the new convection and areas which received 4 to 6
inches overnight based on KHGX radar) over southern Colorado and
northern Wharton counties.

The 25/11Z HRRR finally begins to lift the convection northward
and away from the most unstable airmass by 15Z. Weakening
convergence at the surface should also result in convection
becoming less focused with time this morning as the front weakens.

Bann
WPC.gif
Blake
Boomer Sooner

User avatar
Rip76
Posts: 1433
Joined: Mon Feb 15, 2010 12:38 am
Location: Friendswood
Contact:

Re: June 2020

Post by Rip76 » Thu Jun 25, 2020 10:27 am

That’s a lot of moisture streaming in from the gulf.

Cpv17
Posts: 1450
Joined: Fri Aug 31, 2018 12:58 pm
Location: El Campo/Wharton
Contact:

Re: June 2020

Post by Cpv17 » Thu Jun 25, 2020 10:41 am

Rip76 wrote:
Thu Jun 25, 2020 10:27 am
That’s a lot of moisture streaming in from the gulf.
I suggest everyone to take a look at the 12z HRRR model. Very interesting.

User avatar
Rip76
Posts: 1433
Joined: Mon Feb 15, 2010 12:38 am
Location: Friendswood
Contact:

Re: June 2020

Post by Rip76 » Thu Jun 25, 2020 10:57 am

Can you post it?

davidiowx
Posts: 604
Joined: Thu Jan 23, 2014 2:39 pm
Location: Richmond, TX
Contact:

Re: June 2020

Post by davidiowx » Thu Jun 25, 2020 11:14 am


Post Reply