167
FXUS64 KHGX 142334
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
634 PM CDT Tue May 14 2024

...New AVIATION...

.SHORT TERM...
(This evening through Wednesday Night)
Issued at 120 PM CDT Tue May 14 2024

Looking at a quiet period of weather through Wednesday - which seems
rare this Spring. We got surface high pressure moving overhead today
and ridging building aloft - which is the perfect combination for
drier conditions. Overnight temperatures tonight will drop into the
low to mid 60s for most of the area, and then low 70s along the
immediate coast. Afternoon high temperatures on Wednesday will be a
few degrees warmer than today, getting into the mid to upper 80s,
thanks to the ridge building aloft and a more southeasterly
component of the wind. Overnight lows Wednesday night will be in the
mid 60s to low 70s for most of the area thanks to the onshore flow.

Lingering surface moisture may lead to some patchy fog tonight, but
not looking as widespread nor as dense as this morning. Wednesday
will start out mostly clear, but we will start to see an increase in
cloud cover through the afternoon/evening with some isolated showers
possible late Wednesday night.

The quiet period quickly ends on Thursday, but more on that in the
Long Term below.

Fowler

&&

.LONG TERM...
(Thursday through next Monday)
Issued at 120 PM CDT Tue May 14 2024

Thursday is National Barbecue Day, but it won`t exactly be the
best day to be outside on the grill as we`re expecting yet another
heavy rainfall event for southeast Texas. Going into Thursday, an
upper level trough will push through the southwestern CONUS and
send a few shortwaves out ahead of it. An area of surface low
pressure develops on Wednesday in New Mexico and drifts eastward
into west Texas on Thursday and places southeast Texas in the warm
sector. This leads to a surge of deeper moisture being advected
into the area from the Gulf with PW values reaching 2+" (MAX
percentile: ~2.09") along with increasing instability (especially
west of I-45). There is sufficient deep layer shear coupled with a
30-40 kt LLJ developing west of I-45 on Thursday morning. Capping
is also a bit weaker the further north and west you go on
Thursday, so it`s not surprising that areas north of I-10 and west
of I-45 have a slight risk of severe weather (level 2 out of 5)
on Thursday. There is a marginal risk (level 1 out of 5)
elsewhere. While there is a severe threat, the main concern is
going to be heavy rainfall with the potential for flash flooding.
Let`s dive more into that.

Well above 90th percentile PW values (90th percentile: ~1.76"),
multiple sources of lift (LLJ, PVA, diffluence aloft), and plentiful
instability will all be in place, but there are a few questions
that remain. The main one is when exactly is the heavy rain
threat going to be? If you take a look at the Euro/Canadian, then
the main window for heavy rain is Thursday/Thursday night...but
the GFS/NAM show the main window being Friday/Friday night. This
is due to weak synoptic forcing at the surface, so this is likely
to be mesoscale driven by outflow boundaries. There will be an MCS
pushing through southeast Texas at some point on either Thursday
or Friday, that looks to be certain. Another question is if we
get the MCS on Thursday will the environment be too worked over to
get another round of heavy rain on Friday when the main trough
axis and a weak frontal boundary push through. That answer will
become a bit more clear as we get closer to the end of the work
week. All that being said, there continues to be good agreement on
the higher rainfall totals occuring north of I-10 and east of
I-45...this is unfortunately the area that has seen the bulk of
the rainfall throughout the recent heavy rain events as well.

Minor to major river flooding is ongoing in this area along with
soil moisture remaining saturated, so it wouldn`t take long for
additional heavy rain to become runoff and cause additional
responses along area rivers/creeks. The latest forecast for rainfall
totals remains 2-4" north of I-10 with isolated higher amounts.
These higher amounts still look to occur across the Piney Woods
region. WPC has outlined areas north of I-10 in a moderate risk of
excessive rainfall (level 3 out of 4) for Thursday and a slight risk
(level 2 out of 4) elsewhere. There has been some chatter from WPC
about the potential of a high risk (level 4 out of 4) in future
forecasts if model consensus continues to point towards the rainfall
bullseye occuring in the Piney Woods area. Hopefully that paints the
full picture of what we`re confident in and what we`re not so
confident in as of today. A Flood Watch will likely be needed during
this time period.

The good news is that the forecast for the weekend and beyond
continues to look dry as we transition into a warmer pattern.
Surface high pressure builds in on Saturday along with drier air
behind the passage of a weak frontal boundary. Ridging aloft
builds in late Saturday leading to a warming trend that takes us
into early next week. We start off in the upper 80s/low 90s on
Saturday and become solidly in the low 90s Sunday onward. This
looks to be a much needed extended period of quiet weather to
allow for things to dry out a bit. Heat index values will be in
the upper 90s/low 100s next week though. Let`s hope the heat can
keep the mosquitos at bay at least in the daytime!

Batiste

&&

.AVIATION...
(00Z TAF Issuance)
Issued at 623 PM CDT Tue May 14 2024

Clear skies and light, variable winds can be expected across SE
Texas tonight. Patchy fog could develop during the early morning
hours of Wednesday at some TAF sites, possibly bringing MVFR or
lower VIS. All fog should burn off after sunrise, with winds
strengthening and becoming southeasterly heading into the
afternoon.

03

&&

.MARINE...
Issued at 120 PM CDT Tue May 14 2024

Light northwesterly winds will prevail through the afternoon before
shifting back to southeasterly by this evening. Wind speeds begin to
increase late Wednesday and will likely prompt the issuance of
caution flags as seas subsequently begin to build as well. The
elevated winds persist into Thursday as chances for showers/storms
return and persists into Friday. Winds become a bit lighter heading
into the weekend, and become briefly northeasterly following a weak
frontal boundary pushing through early Saturday morning. Winds
transition back to southeasterly by late Saturday as we trend
towards a warmer and drier pattern.

Batiste

&&

.HYDROLOGY...
Issued at 120 PM CDT Tue May 14 2024

Minor to major river flooding continues for parts of Southeast
Texas, particularly along portions of the Trinity and Brazos rivers.
The following river points are either currently in flood stage or
are forecast to reach flood stage (as of Tuesday afternoon):

- Trinity River (Liberty): Major Flood Stage
- Navasota River (Normangee): Major Flood Stage (forecast)

- Trinity River (Crockett): Moderate Flood Stage
- Trinity River (Riverside): Moderate Flood Stage
- Trinity River (Moss Bluff): Moderate Flood Stage
- Brazos River (West Columbia): Moderate Flood Stage

- Trinity River (Goodrich): Minor Flood Stage
- Brazos River (Rosharon): Minor Flood Stage
- Brazos River (Sugar Land): Minor Flood Stage
- Menard Creek (Rye): Minor Flood Stage
- East Fork San Jacinto (New Caney): Minor Flood Stage (forecast)

The next rounds of heavy rain are expected on Thursday/Friday.
Soils are already saturated from the previous rounds of rainfall in
the Piney Woods and this is where we expect the highest rainfall
totals once again, so we could see the rain become runoff fairly
quickly and caused additional responses along area rivers/creeks.
Please be sure to stay up to date on the latest forecast information.

Please monitor updated forecasts via the NWS AHPS website and/or
the new NWS NWPS webpage (https://water.noaa.gov/) as the river
flood threat continues.

Batiste

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  63  88  67  83 /   0   0  20  80
Houston (IAH)  65  89  69  83 /   0   0  20  70
Galveston (GLS)  73  83  75  82 /   0   0  10  50

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

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