June 2020

[txbear]

Blob over the gulf finally seems to have died off. Moisture return on the way, I would suspect. Radar starting to look colorful albeit scattered and can definitely see the rotation around the low.

Core rain events are something that I haven’t quite gotten a handle on, but seems like the expectation is that the night time cooling and sufficient inflow of moisture will trigger another efficient rainmaker?

[Rip76]

Looks like it may be starting to crank up.

[Cromagnum]

I was just thinking it looked pretty lackluster myself.

[Rip76]

Ramping up now.

[don]

Mesoscale Precipitation Discussion 0372
NWS Weather Prediction Center College Park MD
122 AM EDT Wed Jun 24 2020

Areas affected...Southeast Texas

Concerning...Heavy rainfall...Flash flooding likely

Valid 240522Z - 241145Z

Summary...Thunderstorms will expand in coverage this morning and
produce locally heavy rainfall. Through 12Z /7 AM CDT/ localized
amounts of 3-5" will be possible and some instances of flash
flooding are likely.

Discussion...From a well-defined MCV noted in satellite and radar
imagery over portions of southeast Texas, a front has draped
across the area with some interaction with a lingering boundary
closer to the TX/LA gulf coast. Ahead of this feature, there
continues to be very warm/moist air pooling characterized by
dewpoints in the lower to middle 70s, PWs around 2", and MUCAPE at
or above 2000 J/kg.

Over the next several hours, the MCV is forecast to slowly drift
southward, favoring a continuous fetch of warm/moist air impinging
on the surface boundary/front over the inland areas of southeast
Texas. This pivoting should put a focus of heavy rainfall
somewhere with additional redevelopment likely on the fringes.
Despite limited/weak moisture transport into the area, the
forcing/convergence from the MCV alone is expected to be enough of
a focusing mechanism to drive the heavy rainfall.

The 00Z HREF probabilities remain quite bullish for QPF totals
tonight - maximizing at 100 percent for 1"/hr totals for several
hours and a 50-70 percent chance of 2"/hr totals after 07Z. This
also leads to high probabilities of exceeding the 6-hr FFG and a
slight-moderate signal (30-40 percent) for the 6-hr QPF ending 12Z
to exceed the 10 year ARI. Looking at the latest WoFS runs, it
shows similar thinking to the other hi-res guidance with its
ensemble 50th percentile showing 3" totals just through 10Z alone
with a good signal for 1-2"/hr totals with a slight signal for 5"+
through 10Z alone (heavy rainfall expected to continue beyond end
of WoFS current run).

The combination of the slow storm motions just along/ahead of the
slow moving MCV, more than sufficient environmental parameters
(moisture/instability/convergence), and potential duration over
sensitive areas (including urban areas), some instances of flash
flooding will be likely.

Taylor

[Cromagnum]

Here we go

[Cromagnum]

Almost all of the really heavy action has been well to the south. Been raining too hard to check my rain gauge but I bet its a lot

[tireman4]

000
FXUS64 KHGX 241147
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
647 AM CDT Wed Jun 24 2020

.AVIATION...

A line of shra/tsra is moving east at a pretty good clip and
will likely be east of area TAF sites by 12z with the exceptions
of KGLS and KLBX. Will TEMPO coastal sites through 13z for
thunder and carry VCSH elsewhere. A mix of IFR/NVFR ceilings are
impacting northern TAF sites and these cigs are expected to
dissipate by mid morning with VFR conds developing areawide. With
the upper low remaining over the area today, should get some aftn
shra/tsra to redevelop. Another break in precip is expected this
evening but later tonight, strong sfc surface and moisture flux
convergence should allow for showers and storms to redevelop
especially near coastal TAF sites. A mix of IFR/MVFR ceilings are
also expected to redevelop. 43

&&

.PREV DISCUSSION... /ISSUED 325 AM CDT Wed Jun 24 2020/

UPDATE...

Radar trends not looking too impressive with little to no
backbuilding behind this initial burst of convection. Have gone
back and forth on whether to keep/extend the FFA but just can`t
justify it based on current radar/rainfall rates. Will allow the
FFA to expire at 7 AM. 43

PREV DISCUSSION... /ISSUED 304 AM CDT Wed Jun 24 2020/

SHORT TERM...(Today through Thursday)

A weak upper low over the Brazos Valley will continue to move
slowly E-SE today. A surge of moisture on the east side of this
feature will keep rain chances on the high side today, especially
this morning. Rainfall was spotty yesterday and last night but
parts of the area received between 4 and 6 inches of rain
including 7.40 inches NE of Sebastopol, 6.00 inches near Groveton
and a swath of 3 to 4 inches across Walker county. The 06z HRRR
is aggressive with rain chances and QPF today and and it`s
solution is supported by other CAMs. It looks like another 1 to 3
inches of rain today over mainly the southern and coastal portions
of the area. As a precaution, will extend the FFA through 15z (10
AM) in case pockets of heavy rain develop. A weak disturbance
rotating around the upper low will bring some aftn convection
around the west and south side of the low late this aftn. It`s
possible that the air mass will be worked over this morning that
conds might be too stable for aftn convection will refire but the
airmass is pretty moist so will continue to carry likely PoPS late
today. Clouds and precip should keep temperatures below climo so
MaxT will probably only get into the upper 80`s.

The upper low begins to lose it`s identity and starts getting
squeezed by expanding ridges to the east and to the west. That
said, what ever is left of the low leaves a weakness across the
upper Texas coast. Strong moisture flux convergence along the
coast is progged to develop later tonight so will again carry
likely PoPs along the coast and taper them lower inland.
Differential heating, the weakness aloft and a weak sea breeze
will allow for more showers and thunderstorms on Thursday. High
temperatures on Thursday look similar to today but with a bit more
sun, it`ll probably be a couple of degrees warmer. 43

LONG TERM [Thursday Night through Wednesday]...

Unstable air mass along with PWs still lurking above 2+ inches will
continue to produce areas of showers and thunderstorms across
portions of Southeast Texas well into Thursday night. We may have a
some respite overnight, albeit short lived. Another surge of
moisture from the Gulf will be moving into the local area during the
day Friday. This will once again add fuel to the flame and likely
flare up a few storms across the area, particularly in the late
morning to afternoon timeframe. Thereafter, activity will dissipate
in the evening with only slight chances of development expected
Friday night.

The local weather will gradually transition to a more summertime
pattern this weekend through the upcoming week. Intrusion of Saharan
dust moving from the Caribbean will make its way in this weekend,
which will help limit rain development. The dust will create hazy
skies and pretty sunsets, but could also aggravate respiratory issues
for some folks. Weather activity should be more diurnal in nature
thanks to the slightly lower PWs and dust, and should be developing
mainly in the late mornings and afternoons, dissipating by the
evenings. By next week, area of high pressure in the mid to upper
levels will build across TX, providing some subsidence. Though we
will continue to have moisture transport with the continuous onshore
wind flow, development will be limited as high pressure holds over
our local area through midweek. For this reason, PoPs of up to 30%
were included each day next week.

Mellow high temperatures (upper 80s) will continue through the end
of the work week, rising into the low 90s this weekend in response
to lower cloud coverage and dust. Rising heights next week will
yield high temperatures closer to the mid 90s range. Heat indicies
will also be on the rise, reaching the low 100s Monday through
Wednesday. 24

MARINE...

High pressure over the SE U.S. and low pressure in the lee of the
Rockies will maintain onshore winds through the weekend. The
pressure gradient will tighten at times and winds will
occasionally reach SCEC criteria. Wind and seas will be higher in
and near showers and storms today and again tomorrow. Water
levels today will be slightly elevated and could exceed 3.0 feet
at high tide. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 87 71 90 73 88 / 60 30 40 30 50
Houston (IAH) 86 74 89 77 89 / 80 50 70 30 40
Galveston (GLS) 85 78 88 82 86 / 90 70 70 30 30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flash Flood Watch until 7 AM CDT this morning for the following
zones: Austin...Brazos...Burleson...Chambers...Coastal
Brazoria...Coastal Galveston...Coastal Harris...Coastal
Jackson...Coastal Matagorda...Colorado...Fort Bend...
Galveston Island and Bolivar Peninsula...Grimes...Houston...
Inland Brazoria...Inland Galveston...Inland Harris...Inland
Jackson...Inland Matagorda...Madison...Matagorda Islands...
Montgomery...Northern Liberty...Polk...San Jacinto...
Southern Liberty...Trinity...Walker...Waller...Washington...
Wharton.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 4 PM CDT this
afternoon 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...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

[djmike]

Ok. I thought this was supposed to be waaay more eventful than what it was? What happened?

[mcheer23]

Ok. I thought this was supposed to be waaay more eventful than what it was? What happened?

The large complex of storms that was in the GOM yesterday robbed us of a deep moisture surge from the low-level jet

[Belmer]

Ok. I thought this was supposed to be waaay more eventful than what it was? What happened?

IMO, the explosive development out over the Gulf yesterday morning limited moisture influx throughout the day. Dew Point's weren't as high as the day before and actually stabilized and dropped a couple degrees later in the afternoon. Actually felt quite nice outside yesterday evening. Models didn't really handle the initiation of that Gulf blob well. From what other meso models seemed to indicate was there would be a seabreeze colliding with the leftover outflow boundary from the storms out over Central TX yesterday and both of those would have likely met up somewhere in our region. Those two forcing mechanisms would have likely developed some strong storms as they very slowly propagated southward with the mid-level/surface low aiding in redevelopment behind it (like a pinwheel). Certainly glad we didn't have a flood like the NAM, Euro, WRF were indicating. While no certain model would be considered a win in this event, the HRRR overall did a decent job, especially after the 12z run yesterday as the 18z and 00z NAM was still indicating a deluge over the area.

The low looks to squeeze and wash out over the area this evening and a leftover boundary will likely setup near the coastal areas bringing a focus of redevelopment of isolated to scattered storms today and tomorrow before we dry back out a bit as we expect the SAL to make its debut this season.

[djmike]

Just seems like any time flooding is advertised and all over social media, it never verifies. Its the pop up unexpected storms that dump 7-10” of flooding rains. Here in Beaumont, Sunday NWS showed 80% heavy storms for Monday, Tuesday, Wednesday and Thursday. We had more rain on Monday then this whole week. Tuesday we had nothing. Today, the day of the big possible flooding, we get rain showers no different than a regular 40% chance day. Its getting to the point where if flooding and lots of rain being advertised all over social media, its not gonna happen. So far, my belief still holds.

[Belmer]

Just seems like any time flooding is advertised and all over social media, it never verifies. Its the pop up unexpected storms that dump 7-10” of flooding rains. Here in Beaumont, Sunday NWS showed 80% heavy storms for Monday, Tuesday, Wednesday and Thursday. We had more rain on Monday then this whole week. Tuesday we had nothing. Today, the day of the big possible flooding, we get rain showers no different than a regular 40% chance day. Its getting to the point where if flooding and lots of rain being advertised all over social media, its not gonna happen. So far, my belief still holds.

These meso scale features are often difficult to forecast. Look back a few weeks ago with the large upper-level low parked over the state meandering around sending leftover boundaries all over the place. NWS can forecast percentages all the want as they see fit, but if you want a better insight read their discussions as they'll often mention even when they are uncertain with how things will play out, especially with these types of setups and how one small change can throw a wrench in the whole forecast.

For example, here is an update from 1:07p yesterday from HGX regarding the uncertainty of development because of the thunderstorms out over the Gulf:

Area Forecast Discussion
National Weather Service Houston/Galveston TX
107 PM CDT Tue Jun 23 2020

.UPDATE...

Did make some changes with the short-term grids with respect to
POPs/WX given the current trends where activity along the coast
continues to strengthen and increase in coverage. At this time,
not exactly sure how this will affect the potential for shower/
thunderstorm development later this afternoon over our northern
counties. SREF models have not been great with trends this mor-
ning and afternoon so far...but a lot of the guidance are still
pinging on the potential for widespread rains tonight/early to-
morrow. Did go ahead and issue a Flash Flood Watch starting 7PM
this evening through 7AM tomorrow morning. Stay tuned. 41/11

[Kingwood36]

Over forecasting and the models under delivering...happens all the time

[txbear]

Had a gut feeling that Gulf blob was going to be a bit of a speed bump for the inflow for the overnight rains. Still got a solid, and highly efficient rain out of it though. Had that 'Harvey' sound to it, just a roaring rain. It's a bit of a catch 22; you'd rather over-forecast a possibility of flooding and not verify, but still get something out of it vs. the opposite.

Low seems to be holding firm just east of B/CS, I'd peg sitting right over Roans Prairie/Anderson. NWS still has decent high rain chances through early next week, but I'm hesitant to jump on board with that. I'll take any drop that falls though!

[Cpv17]

2.4” here in Wharton this morning. First decent rain we’ve had in weeks. Was expecting more but I’ll take it.

[tireman4]

000
FXUS64 KHGX 241805
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
105 PM CDT Wed Jun 24 2020

.AVIATION...

Periods of showers with the chance for late afternoon thunderstorms.
Ceilings are lifting to either high end MVFR to VFR this hour.
VFR cats should continue through the remainder of the afternoon
with occasional lowering to MVFR within more moderate rainfall.
regional decks are forecast to lower back into MVFR through the
evening hours. The greatest chance for shower and thunderstorm
redevelopment will be during the overnight early Thursday morning
hours and will likely be focused across more southern terminals
(HOU southward). Ceilings will primarily remain MVFR but there
could be a period of IFR over the northern, more rural air fields.
South to southwest winds will remain up at GLS through the early
Thursday hours. 31

&&

.PREV DISCUSSION... /ISSUED 1049 AM CDT Wed Jun 24 2020/

UPDATE...

The upper low circulating over eastern Texas will slowly open up
into a longwave trough as it moves eastward into the Sabine River
Valley late tonight. In the meantime, expect scattered showers
with the lone rumble of thunder as the low churns across our CWA
this afternoon. Slightly drier western air rotating around the
backside of the low may scatter out more western county afternoon
clouds. Peaks of sun will aid in these counties warming into the
lower to middle 80s. Simply the presence of the upper low will
provide enough regional instability (with near 80 F convective
temperatures) to keep high end PoPs in today for return shower
and thunderstorm activity. Short range high resolution modeling
still wants to redevelop a southern band of convection closer to
the coast, or generally south of I-10, during the overnight early
Thursday morning hours. 31

[DoctorMu]

We had 0.71 inches of rain yesterday as the M/ULL drifted down Hwy 6 toward College Station.

We're the hole in the donut right now as the ULL spins over us. I'll take the cloudy and cool weather, though relieve the A/C.

[Cpv17]

It’s disgusting outside. Muggy as heck!! And not much of a breeze here either. Models are still calling for some pretty good rains over the area the next couple days!

[Rip76]

Too much cloud cover for anything to really get crankin’