902
FXUS64 KHGX 010510
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1210 AM CDT Wed May 1 2024

...New AVIATION...

.SHORT TERM...
(This evening through Wednesday Night)
Issued at 230 PM CDT Tue Apr 30 2024

Isolated storms have developed near the coast/over the Gulf of
Mexico this afternoon. Otherwise the rest of SE Texas remains dry
with benign conditions expected through the end of the day. Patchy
fog will be possible overnight, potentially becoming dense at times
during the early morning hours of Wednesday, with fog chances
greatest in areas east of I-45. Fog development will vary greatly
depending how the lower stratus deck behaves during this overnight
period. Ample moisture and cloudy skies should bring lows for
Wednesday morning in the mid 60s to lower 70s.

On Wednesday, an upper level trough will dig into the Northern Great
Basin, spinning up another surface low over the Rockies. This will
tighten the pressure gradient, strengthening onshore flow and
increasing moisture advection. A plume of 1.75-2.00"+ PWs fills in
from southwest to northeast during the afternoon hours. Weak
impulses aloft coinciding with this moisture influx may bring
isolated to scattered storms across the area during the daytime
hours. Shower/storm activity briefly diminishes late in the
afternoon/early evening as diurnal heating and instability decreases.

A shortwave trough is expected to sweep across Central Texas
Wednesday night, bringing numerous showers and thunderstorms
overnight into Thursday morning. With support from the shortwave,
plentiful moisture, modest instability and support from a 30-35 knot
LLJ, some of these storms will capable of producing locally heavy
rainfall. WPC has portions of the Brazos Valley/Piney Woods area
under a Slight (Level 2/4) Risk of excessive rainfall for Wednesday
night/early Thursday, with a marginal (level 1/4) risk extending
further south to around the I-10 corridor. These areas have
experienced recent heavy rainfall & flooding, with CREST showing
swaths of 40-68% soil moisture north of Conroe. 1Hr FFG for these
locations range from 2-3", so Flash Flooding may develop rather
quickly if any stronger storms were to move over these areas,
especially over Trinity & Walker counties.

The threat of flooding continues into the long term with the arrival

&&

.LONG TERM...
(Thursday through next Monday)
Issued at 230 PM CDT Tue Apr 30 2024

Continued thunderstorm activity will press on into the early part
of Thursday, thanks to robust moisture availability and the
passage of a midlevel shortwave trough. While recent global model
runs continue to show the QPF max just to the northeast of the
area, this could nonetheless result in an additional 2-3 inches of
rainfall across portions of Brazos, Madison, Houston, and Trinity
Counties through late Thursday. Rainfall totals across the
Northern Houston Metro area during this time could reach as high
as 1-1.5 in, while areas along and south of the I-10 corridor
should generally remain at 0.25 in or below. Some locally higher
totals are possible, though greater clarity regarding the extent
and timing of this potential is expected tomorrow as this period
enters the time range of high resolution forecast models.
Additionally, rainfall both over the area and upstream may further
exacerbate ongoing flooding along area rivers and creeks,
particularly across the San Jacinto and Trinity river basins (see
Hydrology section below).

Some additional weak shortwave activity embedded within
an otherwise mostly zonal midlevel flow will continue to result
in rainfall chances through the end of the week, although the
potential for heavier rainfall as we expect late Wednesday into
Thursday will be lower. Despite this, a persistent onshore flow
regime will continue to contribute to elevated moisture levels
which will continue to support the development of scattered
thunderstorms. Some additional lighter rain totals of up to an
inch are possible through Saturday, with the greatest rainfall
chances remaining north of the I-10 corridor.

Drier conditions look to return heading into the weekend as a
midlevel ridge builds over the area while a surface frontal
boundary stalls to our north. This will be accompanied by a
warming trend, with temperatures rising gradually into the mid to
upper 80s by the end of the week. By Monday, most locations will
border on the 90 mark with even higher temperatures possible on
Tuesday. With this being an early season heat event and high
moisture levels still in place, heat safety precautions may need
to be taken. Early indications show max WBGT values of 81-83 on
Monday and 82-85 on Tuesday.

Cady

&&

.AVIATION...
(06Z TAF Issuance)
Issued at 1153 PM CDT Tue Apr 30 2024

No major changes from the previous TAF package. Still expecting CIGs
to fall as we approach sunrise...with mostly MVFR conditions (with a
few spots of IFR). Onshore winds will be increasing through the day,
on into Weds evening (with gusts up to 20-24kts possible). We should
get some spotty activity by the afternoon...but the bulk of the more
organized storms/rain should be during the latter part of this pack-
age. The best chances for the storms will be generally across north-
ern third/half of the CWA. 41

&&

.MARINE...
Issued at 301 AM CDT Tue Apr 30 2024

Persistent moderate onshore winds are expected through the
remainder of the week and into the weekend, with wind speeds at
times occasionally bordering on Advisory thresholds. Periods of
showers and storms are possible during the course of the rest of
the week, particularly on Thursday. However, the bulk of the rain
should remain inland. Rain chances diminish heading into the
weekend, with onshore flow remaining in place.

Cady

&&

.HYDROLOGY...

Ongoing flooding along area rivers, particularly the Trinity and
San Jacinto, continues to persist. The following river points
continue to remain at or above flood stage as of this afternoon:

- Trinity River (Goodrich): Major Flood Stage
- Trinity River (Liberty): Moderate Flood Stage, rising to Major
  Flood Stage
- Trinity River (Riverside): Moderate Flood Stage
- Trinity River (Romayor): Action Stage, rising to Moderate Flood
  Stage
- Trinity River (Moss Bluff): Minor Flood Stage
- Menard Creek (Rye): Major Flood Stage
- San Jacinto (New Caney): Action Stage, rising to Major Flood
  Stage
- San Jacinto (Cleveland): Moderate Flood Stage

Additional rainfall over the next few days, both over the area and
upstream, may result in prolonged and potentially further
exacerbated river flooding. Remember to heed any instructions from
your local officials and to never travel through flooded roadways. 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.

Cady

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  68  85  71  84 /   0  30  50  60
Houston (IAH)  70  84  74  85 /  10  30  30  40
Galveston (GLS)  73  79  73  81 /  10  20  20  20

&&

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

$$

SHORT TERM...03
LONG TERM....Cady
AVIATION...41
MARINE...Cady