630
FXUS64 KHGX 310538
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1238 AM CDT Fri May 31 2024

...New AVIATION...

.UPDATE...
Issued at 745 PM CDT Thu May 30 2024

Strong line of thunderstorms is currently moving through our
northern and central counties. As of 7:45PM, the line of storms
extended from Grimes County through Montgomery, San Jacinto, and
Polk Counties. Strong winds gusts and small hail have been common
reports from these storms. Locally stronger storms within the
line may produce larger hail and wind gusts over 60 MPH. The line
will continue southward, impacting the Houston metro this
evening. Most model guidance shows the line weakening as it heads
south. But thus far, the line has exceeded most guidance`s
expectations. There is an increasing chance of the line holding
together and making it to the coast later this evening. Damaging
wind gusts and hail, along with frequent lightning and heavy rain
will be the primary concern.

Our forecast still calls for a chance of additional thunderstorms
by early Friday morning. However, we will need to assess how much
instability remains following the current storms in order to
determine whether or not the chance of morning storms has
decreased.

&&

.SHORT TERM...
(This evening through Friday Night)
Issued at 332 PM CDT Thu May 30 2024

Our primary concern as of writing this AFD (3PM) is the building
convection over portions of N Texas this afternoon. The overall
synoptic pattern continues to features a train of shortwaves embedded
in the WNW to NW flow aloft. One such shortwave in conjuction with
bountiful LL instability and moisture is enhancing the aforementioned
convection which has recently evolved into a more organized line of
thunderstorms. Some cold pooling is evident as per the surface obs in
the MCS`s wake. The convection as been somewhat pulsy, with outflow
boundaries outrunning the convection along the line`s western flank.
CAMs guidance is all over the place regarding the line of storms and
its potential time of arrival in our CWA. But structurally speaking,
the guidance that has best initialized the line features a more
progressive forward motion, bringing storms into our northern counties
by this evening. Therefore, we are starting to lean more towards a
scenario similar to the ARW which has the line reaching our
northern most counties (Piney Woods area) by 5-7PM and potentially
the Brazos Valley by 6-8 PM if the western flank doesn`t fall
apart. If the line continues to hold together, then these storms
could reach the I-10 corridor by 10PM-12AM and the coast by
1-2AM. The primary concern will be damaging wind gusts and hail
along with localized flooding. The LL shear profile is not a
quintessential tornado environment but we still cannot rule out an
isolated thunderstorm capable of a tornado. If the line does not
hold together enough to push through our region, then instability
would be saved for another possible MCS that approaches from the
northwest later tonight thanks to another shortwave. So in other
words, if these evening storms behave more like the ARW, then
there may not be enough instability left for the next round of
thunderstorms. There would be no (or maybe just weaker) late night
/ early morning storms. But if the ARW scenario does not pan out,
then that would open the door for a round of thunderstorms
(possibly severe w/ hail and damaging winds) later tonight into
the early morning hours on Friday.

So what should you do with such an uncertain forecast? Remaining
weather aware is a good start. Have multiple ways of receiving
warnings. Generally speaking, stay in tune with the weather this
evening and tonight. This is one of those forecasts that can easily
change due to the complexity of the situation. We will obviously be
keeping a very close eye on the radar this evening and tonight.
Frequent updates to the forecast may be warranted.

Friday`s forecast will depend on how tonight unfolds. An early morning
MCS featuring a period of low clouds and showers in its wake could keep
temperatures cooler than currently predicted (85-90F in the current
forecast) and possibly limit the intensity of afternoon/evening
convection. However, if Friday starts out with less
rain/thunderstorm activity, then the environment may become
hotter and more unstable. With the continuance of the mid/upper
level shortave train, Friday will be another day to watch for
strong to severe thunderstorms, with damaging winds being more of
a concern than hail.

Self

&&

.LONG TERM...
(Saturday through next Wednesday)
Issued at 332 PM CDT Thu May 30 2024

A shortwave trough will pass over the Red River Valley Saturday
morning, bringing another round of showers and thunderstorms through
the afternoon. While these storms should be fairly progressive, PWs
in excess of 1.8" will be sufficient to produce locally heavy
rainfall within some of these storms. Therefore, WPC has most of SE
Texas under a Marginal (level 1/4) risk of excessive rainfall on
Saturday. Forcing from this shortwave, combined with sufficient wind
shear and instability could produce strong to severe storms during
this period as well. Therefore, SPC has areas along and north of the
I-10 corridor under a Marginal (level 1/5) risk of severe weather
for Saturday. If severe storms do develop, damaging winds and hail
will likely be the main threat. Another, slightly stronger, midlevel
shortwave will pass overhead Sunday morning, bringing yet another
round of showers/storms. The parameter space for Sunday is still
very similar to that of Saturday, so stronger storms with locally
heavy rainfall will still be possible during that day as well.

Ridging begins to build over Mexico early next week. Impulses riding
the peripheral of this ridge (with this moisture-rich environment)
could bring some isolated showers/storms through mid-week, mainly
in areas north of I-10 closer to the Brazos Valley/Piney Woods
area. NAEFS and GEFS 850mb temperatures surpass the 90th
climatological percentile by Tuesday, with ridging expected
amplify across the Plains on Wednesday as a Rex-block-like
pattern develops over the Western CONUS. The latest suite of
global models indicate 850mb temperatures reaching the 21-26C
range by mid-week with robust WSW/SW flow in the lower levels.
This all looks to bring hotter conditions, with highs reaching the
upper 80s to mid 90s on Tuesday/Wednesday. Persistent onshore
winds are also progged to keep dewpoints in the mid/lower 70s
during this period, even when factoring in the effects of afternoon
mixing. Heat Indices are estimated to reach 100-108 degrees by
Wednesday, signifying an increasing heat risk for next week.

Models suggest that a frontal boundary could trek southward
through the Plains later in the week, bringing some mild relief
from the heat. However, frontal systems have a tendency to stall
out before reaching SE Texas during this time of the year, so
relief may be much further away. In fact, if this boundary stalls
out close to our area, pooling moisture and compressional heating
could further exasperate the heat risk.

Regardless, we`re entering the climatological summer for SE
Texas/the Houston, so practicing heat safety will become
especially important in the coming weeks/months. Remember to
drink plenty of fluids, wear lightweight clothing and be sure to
take breaks out of the sun. Heat is the #1 weather-related killer
in the U.S. each year, so be sure to not underestimate the danger
it poses.

03

&&

.AVIATION...
(06Z TAF Issuance)
Issued at 1219 AM CDT Fri May 31 2024

Additional rounds of showers and thunderstorms are expected
through the next 24 to 36 hours, but confidence is abnormally low
on the exact timing and locations of the storms. The first line
of storms is expected to move through the region between 7 and 12z
from the Brazos Valley down to the coast. There is great
uncertainty with how strong these storms will be and if the line
will make it all the way to the coast (it may dissipate as it
heads towards the I-10 corridor). There could be temporary IFR
conditions as these storms move overhead with reduced visibility
due to heavy rain, lower CIGs down to around 1000-2000ft, and
gusty winds. There should be a lull in the TS activity during the
early to mid morning hours, but another line of strong
thunderstorms may move through the area during the late morning
hours through the afternoon. Additional showers and storms will be
possible late tomorrow night.

Generally expecting southeasterly winds through the period, but
will become northerly briefing following the line of storms before
eventually swinging back around to the southeast. Patchy MVFR
conditions are expected through sunrise with BKN 1500-2500ft. VFR
conditions will generally prevail through the day with MVFR
conditions returning tomorrow night.

Fowler

&&

.MARINE...
Issued at 332 PM CDT Thu May 30 2024

Light to moderate onshore flow and seas of 3 to 6 feet are expected
through mid next week, warranting caution flags at times, especially
during the overnight hours. Rounds of showers and storms will be
possible into the weekend, with rain chances tapering off next week.
Some of these storms could become strong to severe, producing
damaging wind gusts and locally elevated seas. Persistent onshore
flow will bring a high risk of rip currents into the upcoming work
week.

03

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  73  88  75  90 /  30  50  10  20
Houston (IAH)  75  88  77  90 /  30  60  10  20
Galveston (GLS)  78  86  81  86 /  30  40  20  20

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Should Exercise Caution until 7 AM CDT this morning
     for GMZ330-335-350-355-370-375.

&&

$$

SHORT TERM...Self
LONG TERM....03
AVIATION...Fowler
MARINE...03