004
FXUS64 KHGX 132009
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
309 PM CDT Mon May 13 2024

...New SHORT TERM, LONG TERM, MARINE, HYDROLOGY...

.SHORT TERM...
(This evening through Tuesday Night)
Issued at 304 PM CDT Mon May 13 2024

A very active afternoon with scattered to numerous strong to severe
thunderstorms across portions of Southeast TX. The forecast for this
afternoon and evening remains on track. Current mesoanalysis show a
favorable environment with increasing PVA and strengthening upper
jet over our region. The interaction of passing shortwaves aloft
along with different surface boundaries (quasi-stationary warm front
and sea-breeze/coastal boundary) will continue to be the main focus
for convection over the next several hours. Surrounding soundings
and sfc obs show steep mid-level lapse rates (~ 7 C/km), MUCAPE
at/greater than 4,500 J/kg with 0-6km bulk shear around 40 to 50
knots, sfc dewpoints mainly in the 70s. These ingredients will be
enough to support strong updrafts along the boundary (-ies). With
decent instability in the hail growth zone, and wet bulb zero height
around 11 kft and EBWD around 50 knots, large hail up to around 2
inches will continue to be the main severe threat this afternoon. As
the main stalled boundary pushes southeastward into the coastal
waters late this afternoon and evening, the threat will slowly
transition to wind threat. Models show 0-3km helicity into the 100-
150 m2s-2 range and 0-1km helicity greater than 90-120 m2s-2 east
of I-45, suggesting a secondary threat of damaging winds. Tornado
threat is low given 0-1 km bulk shear near 5-10 knots. However, a
few mesovortices/rotation cannot be ruled out, especially near
boundaries this evening.

A Severe Thunderstorm Watch is in effect for most of southeast TX
until 8PM. Locally heavy rainfall is also expected; thus isolated
flash flooding will be possible. Additional rainfall totals of 1 to
3 inches can be expected through late this evening with isolated
higher amounts. Will continue with a Flood Watch for areas
particularly north of I-10 through 7PM this evening.

Storms should gradually taper off from west to east this evening as
the boundary pushes offshore. Drier northerly winds will filter in,
leaving us with dry conditions for the rest of the short-term
period. Mostly sunny skies will lead to warmer conditions on
Tuesday. Highs will generally be from the upper 80s to low 90s.

JM

&&

.LONG TERM...
(Wednesday through next Sunday)
Issued at 304 PM CDT Mon May 13 2024

A brief period of ridging aloft will keep things on the quiet-side
on Wednesday behind the departing upper level trough that brought
strong storms/heavy rain earlier in the week. With 850mb
temperatures in the 90th percentile along with drier air in place
(PW values less than 1"), we`ll see temperatures reach the upper
80s/low 90s. This quiet period will be the calm before the storm so
to speak as we`ll have another upper level trough approaching from
the southwestern CONUS. On Thursday, the upper level trough will be
around the Four Corners region and will send out a few shortwaves
out ahead of it. Surface low pressure is induced out in West TX on
early Thursday, which places us in the warm sector. There will be an
abundance of instability in place along with deep moisture (PW
values greater than 2") in addition to some decent deep layer shear.
As a result, widespread showers and thunderstorms are expected on
Thursday as a shortwave pushes through. Another round of storms is
in the cards for Friday as the trough pushes through along with a
weak boundary. WPC already has most of Southeast TX in a slight risk
of excessive rainfall (level 2 out of 4) on Thursday and areas
around/east of I-45 in a marginal risk of excessive rainfall (level
1 out of 4) for Friday, so be on the lookout for locally heavy
rainfall at the end of the work week.

The highest of the rainfall totals between Thursday/Friday as of
right now are anticipated to occur north of I-10 especially in the
Piney Woods area...this is unfortunately the area that has seen the
bulk of the rainfall recently. Soils remain fairly saturated up
there, so quick responses along area rivers/creeks/bayous are
possible as rainfall may quickly become runoff. Rain chances linger
into Saturday before clearing out as drier air filters in along with
surface high pressure. Ridging aloft builds in towards the latter
half of the weekend and into early next week leading to a warming
trend. Temperatures are expected to reach the low 90s on Sunday and
these will continue into early next week. As far as temperatures for
earlier in the week, with the rainfall expected on Thursday and
Friday, expecting highs in the low to mid 80s. Low temperatures will
generally be in the upper 60s to low 70s throughout the long term
period, but there is an upward trend going into early next week
towards the low to mid 70s.

Batiste


&&

.AVIATION...
(18Z TAF Issuance)
Issued at 1248 PM CDT Mon May 13 2024

An active afternoon and evening with strong to severe
thunderstorms expected near/around the terminals. Thunderstorms
will continue to develop and move eastward through early this
evening. The best potential for severe thunderstorms will be for
terminals south of CXO, though an isolated strong storm or two
cannot be ruled out near/around CLL/UTS terminals. Large hail and
damaging winds are the main threats. Gusty erratic winds and
reduced visibility can be expected with any strong storms.
Conditions should gradually improve late this evening. Benign
aviation conditions are expected on Tuesday with northwest to
north winds around 5 to 10 knots.

JM

&&

.MARINE...
Issued at 304 PM CDT Mon May 13 2024

Light to occasionally moderate onshore flow will persist throughout
most of the day along with seas in the 4 to 6 foot range. The main
story for today though will be a line of strong to severe storms
pushing off the coast in the early evening hours. These storms may
bring strong wind gusts, heavy rain, and hail. A brief period of
offshore flow is expected behind these storms. Offshore flow will
prevail through most of Tuesday before transitioning back to onshore
flow on Tuesday night. Wind speeds begin to increase late Wednesday
and will likely prompt the issuance of caution flags. The elevated
winds persist into Thursday as we get our next round of
showers/storms and this will likely be followed by another round on
Friday as well. Winds become a bit lighter heading into the weekend,
but remain generally in an onshore direction.

Batiste

&&

.HYDROLOGY...
Issued at 304 PM CDT Mon May 13 2024

A Flood Watch remains in effect through 7pm Monday evening for
portions of the Piney Woods and the Brazos Valley. A line of strong
to severe storms will push through Southeast TX this
afternoon/evening. Soils in the watch area already fairly saturated
from last week`s heavy rain events. This means that heavy rainfall
will likely become runoff quickly leading to additional responses
along area rivers/creeks/bayous. Flash flooding is also a
possibility in these locations. Expecting 1-3" of rainfall with
isolated higher amounts today.

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 Monday 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): Moderate Flood Stage (forecast)

- Brazos River (Rosharon): Minor Flood Stage
- Brazos River (Sugar Land): Minor Flood Stage
- Long King Creek (Livingston): Minor Flood Stage
- Menard Creek (Rye): Minor Flood Stage (forecast)

Remember to heed any instructions from your local officials and to
never travel through ANY 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.

The next rounds of heavy rain are expected on Thursday/Friday, so be
sure to stay up to date on the latest forecast information.

Batiste


&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  64  87  64  89 /  20   0   0   0
Houston (IAH)  68  90  66  90 /  60   0   0   0
Galveston (GLS)  72  85  74  83 /  60   0   0   0

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flood Watch until 7 PM CDT this evening for TXZ163-164-176>179-
     196-198>200.

GM...Small Craft Should Exercise Caution until 7 PM CDT this evening
     for GMZ350-355-370-375.

&&

$$

SHORT TERM...JM
LONG TERM....Batiste
AVIATION...JM
MARINE...Batiste