928
FXUS64 KHGX 051502
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1002 AM CDT Sun May 5 2024

...New UPDATE...

.UPDATE...
Issued at 947 AM CDT Sun May 5 2024

Bulk of the shortwave that brought another widespread area of
showers/tstms to the region has passed to the E/NE. Exception is
the tail end which is generally situated along the I-10 corridor.
An east-west oriented boundary and pooling 2" PW`s are (and will
be) the focus for some embedded stronger downpours for the rest
of the day as it trends ese into the H85 20-30kt llvl jet. Good
news is this is mostly impacting areas that have seen the least
amount of rainfall this past week. Not so good news is that it is
falling in a more metropolitan area w/ more concrete. Any heavy
rain that falls in a short time period will be prone to runoff and
cause street flooding and rises on area creeks, streams, bayous.
Given latest hires model trends, and outside of the ongoing river
impacts, think any additional ff impacts will probably be more on
the localized scale. There always seem to be a few overperforming
cells, so overall messaging will remain pretty much status quo
into the early evening followed by a more optimistic outlook
thereafter in terms of significant rainfall chances/coverage.  47

&&

.SYNOPSIS...
Issued at 205 AM CDT Sun May 5 2024

- The next round of showers and storms has arrive and will
  continue into this afternoon. Some storms may become strong to
  severe with gusty winds and hail possible.
- Flood Watch remains in effect for counties along and north of
  I-10 through 7pm this evening. Generally expecting up to 1-3"
  of rain within the Watch area with locally higher amounts of up
  to 4-8" if and where training storms develop.
- Moderate to Major River Flooding will continue for at least the next
  several days along parts of the Brazos River, Trinity River and
  West Fork/East Fork of the San Jacinto River.
- Hot and humid weather will be in place for the majority of the
  upcoming work-week

&&

.SHORT TERM...
(Today through Monday Night)
Issued at 205 AM CDT Sun May 5 2024

Showers and thunderstorms, some strong to severe, have already begun
to develop north of Montgomery County. We can expect an increase
in the coverage of these showers and storms through the next
several hours producing a quick downpour of 0.5" of rain or less,
gusty winds, and maybe even some hail. The main concern will come
during the early morning as a now-developing MCS moves through
the region from west to east bringing with it heavy rainfall and a
chance of strong to severe thunderstorms. MCS looks to pass
through the B-CS area between 4am to 5am, the I-45 Corridor
between 6am and 8am, and then through Liberty/Chambers counties by
8am and 10am. Rain rates with the strongest storms within this
MCS will be around 1-3" per hour, so the quicker it progresses
through the area the better. The MCS will also bring the a threat
of strong gusty winds, hail, and cannot out-rule a brief tornado
either. SPC maintains a Marginal (level 1 of 5) for Severe Storms
across the region.

Once the MCS is through, the rain threat does not end. CAMs have
been indicating a west-to-east band of showers and thunderstorms
developing and training somewhere across the region in the wake
of the MCS. Exact location of where this band of showers and
thunderstorms develops will be determined by meso-features unknown
at this time, but it is more likely to develop somewhere between
I-10 and the Pineywoods region. Chance for showers and storms
will continue into the afternoon/early evening hours before dying
out.

A Flood Watch is in effect through 7pm for counties along and
north of I-10. After all the rainfall we have received in the
past week, the soils are very saturated. FFG (both 1 and 3 hour)
are around 2 to 3" for areas along and north of I-10 with Walker
County into the Pineywoods region being especially susceptible.
Within the Watch area, generally expecting up to around 1-3" of
rain through Sunday evening with isolated higher amounts of 4-8"
possible. These higher amounts will most likely be seen where the
strongest storms of the MCS move over and where the training line
of showers and storms develop. The excessive rainfall outlook for
today from the WPC has a Moderate Risk (level 3 of 4) for areas
along and north of I-10, Slight Risk (level 2 of 4) for most of
the rest of the area with an area of Marginal Risk (level 1 of 4)
for the counties around Matagorda Bay. There is ongoing moderate
to major river flooding along portions of the Trinity River,
Brazos River, West & East Forks of the San Jacinto River (more on
this in the Hydro section below). Not only does this mean that the
rainfall that happens today will be slower than normal to drain,
but may also see additional rises of the rivers.

Please remember:
- Do not drive through or play in flood waters. Never truly know
  how deep the water is, what is lurking in the waters, nor how
  fast the water is moving.
- Do not go around barricades. Even if the flood waters have gone
  down, the ground may not be stable.
- Do no return to homes until officials deem it safe.

Weak midlevel ridging moves overhead Sunday night into Monday,
keeping the rain chances low. However, cannot out-rule a pop-up
shower Monday afternoon due to lingering low level moisture and
daytime heating. High temperatures Sunday will be in the upper 70s
to low 80s with overnight lows in the upper 60s to low 70s.
Temperatures rise on Monday thanks to the ridging aloft and
southerly flow at the surface with high temperatures in the mid to
upper 80s and low temperatures Monday night in the low to mid 70s.
Heat indicies will approach the low to mid 90s on Monday - but this
will only get worse as we head into the long term.

Fowler

&&

.LONG TERM...
(Tuesday through Saturday)
Issued at 205 AM CDT Sun May 5 2024

Southwesterly flow aloft, southerly flow at the surface bringing
Gulf fueled moisture, and mostly sunny skies will lead to our first
real taste of summer in SE Texas during the middle part of the week.
High temperatures Tuesday through Thursday will be in the low to
even mid 90s for most of the region. Heat indicies will be in the
upper 90s to near 100 degrees on Tuesday and Wednesday, and then
even up to 105 degrees on Thursday. I even suspect that the very
saturated grounds due to the recent rainfall may result in even
higher dew points across the area making the heat indicies even
worse. Our bodies have not acclimated yet to the heat and humidity,
so these early season heat events end up being more troublesome.
While it will likely be below normal Heat Advisory thresholds, there
may be a need for a Heat Advisory Wednesday or Thursday since these
early season events can be more impactful. Either way, please be
sure to stay hydrated and take frequent breaks if needed to be
outside and while doing post-flood recovery efforts.

While rain chances will remain minimal through Wednesday, a slow
moving boundary from the north will help bring increased coverage of
showers and thunderstorms Thursday into Friday. Global models are
currently hinting that this boundary is able to push all the through
the region with high pressure settling in for Saturday. However, I
am not super confident this boundary will actually make it all the
way off the coast as we have been burned by this type of feature
beyond Day 5 many times during this time of year.

Fowler

&&

.AVIATION...
(12Z TAF Issuance)
Issued at 627 AM CDT Sun May 5 2024

A line of showers and thunderstorms is currently moving though the
Houston metro area early this morning. CIGS remain largely around
VFR/MVFR levels, with lower CIGS/VIS possible as those
thunderstorms pass. Expect a brief lull in shower/storm activity
behind this line, with CIGs lifting to VFR levels heading into the
afternoon. Models suggest a second round of showers/storms
developing in the afternoon through the early evening. MVFR CIGS
fill back in this evening, with IFR CIGS and some patchy fog
developing overnight into early Monday morning. CIGS/Fog should
improve/clear after sunrise.

03

&&

.MARINE...
Issued at 205 AM CDT Sun May 5 2024

Can expect increasing showers and storms through daybreak with
possibly line of strong to even severe thunderstorms moving through
during the early morning hours today (between 5 and 10am). Scattered
showers and storms will then be possible through the evening.
Onshore winds around 10 to 15kt with occasional gusts to 20kt will
prevail through midweek with seas around 4 to 6ft. Small Craft may
need to exercise caution levels at times. Because of the continued
onshore flow, there will be a moderate to high risk of strong rip
currents through the next several days. Drier, but much warmer
conditions are expected through midweek.

Fowler

&&

.HYDROLOGY...
Issued at 401 PM CDT Sat May 4 2024

The Flood Watch has been extended to 7pm CDT Sunday evening and
expanded to now include Austin/Colorado Counties. Additional heavy
rainfall is expected in areas that have already received excessive
amounts of rain over the past few days. At this time, we are
anticipating an average of an additional 1-3" of rain with smaller
areas of 4-8" possible within the watch area. With soils already
saturated, this will likely lead to quick runoff and rapid responses
along area rivers/creeks/bayous.

Moderate to major river flooding continues for parts of Southeast
Texas, particularly along portions of the Trinity, San Jacinto, and
Navasota rivers. The following river points are either at or
forecast to go into Major flood stage:

- Trinity River (Riverside): Major Flood Stage
- Trinity River (Liberty): Major Flood Stage
- Trinity River (Goodrich): Major Flood Stage
- Trinity River (Moss Bluff): Moderate forecast to go to Major
- West Fork San Jacinto (Conroe): Major Flood Stage
- West Fork San Jacinto (Humble): Major Flood Stage
- San Jacinto (Sheldon): Major Flood Stage
- East Fork San Jacinto (New Caney): Major Flood Stage
- Navasota River (Normangee): Major Flood Stage

Remember to heed any instructions from your local officials and
to never travel through flooded areas or roadways. TURN AROUND,
DON`T DROWN. 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)  80  70  85  73 /  50  20  10   0
Houston (IAH)  80  72  86  75 /  70  20  10   0
Galveston (GLS)  79  74  81  75 /  60  20   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flood Watch until 7 PM CDT this evening for TXZ163-164-176>179-
     195>200-210>214-300-313.

     High Rip Current Risk until 7 PM CDT this evening for TXZ436>439.

GM...Small Craft Should Exercise Caution until 7 PM CDT this evening
     for GMZ370-375.

&&

$$