455
FXUS64 KHGX 102347
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
647 PM CDT Fri May 10 2024

...New AVIATION...

.SHORT TERM...
(This evening through Saturday Night)
Issued at 337 PM CDT Fri May 10 2024

Hope everyone has been able to enjoy the low dew points today as the
high humidity gets turned back up starting tomorrow night as onshore
flow begins again. Very weak ridging aloft will continue through
tomorrow, but some shortwave passing through will keep partly to
mostly cloudy skies in the forecast (and even when we do get breaks
in the clouds, the hazy skies will continue thanks to the fires down
in Mexico). Winds will turn from NE to E to ESE through the day on
Saturday as the surface high pressure moves into the Central Gulf
Coast. The onshore winds will lead to high moisture levels making
their way back into SE Texas, and with that the chance for
precipitation. While we likely won`t see any showers during the
daylight hours on Saturday, some isolated showers and storms may
begin to move into the area from the west overnight Saturday night
into Sunday morning. But more on this in the Long Term section below.

Low temperatures tonight will be in the mid 60s north of Harris
County, upper 60s to low 70s along the I-10 corridor, and then mid
70s along the immediate coast. High temperatures Saturday afternoon
will be fairly close to normal with afternoon getting up into the mid
to upper 80s. Low temperatures Saturday night will be a few degrees
warmer compared to tonight thanks to the return of the onshore flow.

Fowler

&&

.LONG TERM...
(Sunday through next Thursday)
Issued at 337 PM CDT Fri May 10 2024

Chance of rain will increase Sunday as upper level disturbances
embedded in the quasi zonal flow aloft move across Southeast TX
while a warm front pushes north northeastward, instability
increases, and a surge of moisture moves in from northwestern Gulf
of Mexico. On Sunday morning, we could begin to have isolated to
scattered shower and thunderstorm activity over most of the region,
but we will have to see if the cap is going to limit development for
us. As the day progresses however, storm coverage is expected to
increase as the cap weakens, with areas north of I-10 possibly
having widespread chances of rain for much of the afternoon into
evening hours. Model guidance shows the surge of moisture carrying
PWs between 1.8 to 2.1 inches moving across the region in the
afternoon to evening as some vort maxes also push through. Moisture
levels along the mid levels will also be high. Thus, periods of
heavy rainfall, in particular over portions north of I-10, can be
expected. WPC has placed a Slight Risk (threat level 2 out of 4) for
excessive rainfall for much of Southeast TX, except the areas in
and around Matagorda Bay, which is under a Marginal Risk (threat
level 1 out of 4). Some storms could become strong at times and
may produce strong gusty winds and hail. SPC currently has a
Marginal Risk (threat level 1 out of 5) for severe thunderstorms.

Shower and thunderstorm activity is expected to decrease Sunday
night as we loose some moisture and instability and the cap tries to
re-develop. However, periods of isolated to scattered activity will
still be possible. Breezy conditions are possible Sunday evening
into Monday morning as a low level jet develop over us.

On Monday, a stormy weather pattern will emerge once again. Upper
level disturbances will continue to move through as an upper level
trough digs into the Southern Plains and a cold front makes its way
across Central TX. Another surge of moisture from the Gulf will move
into Southeast TX sometime mid morning to afternoon hours while the
cap weakens/instability increases and several vort maxes move
overhead. Model guidance/forecast soundings show CAPE values of 3000-
4500 J/kg over much of the region Monday afternoon and evening, with
the highest values situated over areas north of the I-10 corridor.
They also indicate SFC-6km shear values between 40-50 knots, PWs
near 2.0 inches, steep mid level lapse rates, dewpoints in the mid
70s. Not to forget that this is all setting up just ahead of an
approaching cold front, which is progged to move across the region
sometime Monday night.

Overall, the set up could support another day of heavy rainfall on
occasion as well as strong thunderstorms capable of producing hail
and strong winds. Although it is too soon to tell exactly where and
when the stronger storms and heaviest rainfall will be on Sunday and
Monday, the latest guidance favors areas north of I-10. It is also
too soon to say how this rainfall will affect our ongoing river
flooding, but please be aware that additional rises along creek,
small streams and rivers will be possible. That being said, our
estimated rainfall totals at this time from Sunday into Monday are
generally 2-4 inches with isolated higher amounts over areas north
of I-10 and 1-2 inches with isolated amounts elsewhere. Please
continue to monitor the latest forecast and make sure to have
multiple ways of receiving warnings.

A respite can be expected on Tuesday and Tuesday night as drier air
moves in behind the cold front. Some isolated showers could occur on
Wednesday as moisture begins to move back into the region and a mid
to upper level disturbance moves close to our western counties. On
Thursday, scattered showers and thunderstorms will be back on the
table as another series of disturbances move aloft along with a
surge of low level moisture, good instability in place and a warm
front moves over the region. Rain chances decrease sometime
Thursday night into Friday morning as another cold front pushes
across Southeast Texas.

With respect to temperatures, the cloudy skies and rainfall will
allow for high temperatures in the upper 60s to low 70s over areas
north of I-10 and the low 70s elsewhere. The lows Sunday night into
early Monday morning will be in the upper 60s to low 70s over areas
north of I-10 and in the low to mid 70s elsewhere. Tuesday and
Wednesday, the highs will increase into the mid to upper 80s and the
lows will be generally in the mid to upper 60s inland and the low
70s along the immediate coasts. Highs could remain in the 80s on
Thursday but exact values will depend on where and when the rain
develops.

24

&&

.AVIATION...
(00Z TAF Issuance)
Issued at 641 PM CDT Fri May 10 2024

VFR conditions ongoing with VFR expected to prevail through the
majority of the period. Very light patchy fog may develop during
the overnight hours. The caveat would be if winds were able to
become calm enough to allow for development. Have continued to
withold this from the TAFs given the low probability of
occurrence. Light easterly winds of less than 10 knots expected
overnight, becoming easterly to southeasterly through Saturday.
Clouds will begin to increase Saturday night as southerly winds
draw moisture into SE Texas...CIGs may approach or reach MVFR
levels around 20Z Saturday.

&&

.MARINE...
Issued at 337 PM CDT Fri May 10 2024

Moderate to occasionally strong northeast to east winds and seas
of 3 to 6 feet will continue through Saturday. Caution flags are
in place for the Gulf waters through Saturday evening, but may be
upgraded to a Small Craft Advisory for Saturday morning. Moderate
onshore flow is expected Sunday and Monday. A cold front will move
into the coastal waters Monday night or early Tuesday morning and
will result in variable winds on Tuesday. Onshore flow could
return by Tuesday evening and continue through Thursday. Another
cold front is expected to push across the region sometime Thursday
night, resulting in moderate to strong offshore winds on Friday.

Periods of showers and thunderstorms can be expected Sunday
through Monday night, some could be strong at times. Another round
of showers and storms can be expected on Thursday and Thursday
night.

24

&&

.HYDROLOGY...
Issued at 337 PM CDT Fri May 10 2024

Although there have been decreases in the water levels along the
rivers, some will remain swollen for days (possibly weeks). Do NOT
go around barricades and stay out of the floodwaters. Do NOT return
to homes until officials deem that it is safe.

River flooding continues for parts of Southeast Texas, particularly
along portions of the Trinity river. The following river points are
at Moderate or Major flood stage as of Thursday afternoon:

- Trinity River (Liberty): Major Flood Stage
- Trinity River (Moss Bluff): Moderate Flood Stage
- Trinity River (Riverside): Moderate Flood Stage
- Trinity River (Goodrich): Moderate 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.

Also of note is that the downstream runoff from the previous
rainfall will cause continued rises along the Brazos River through
the end of the week.

24

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  65  83  67  79 /   0  10  20  80
Houston (IAH)  69  85  70  82 /   0  10  20  70
Galveston (GLS)  74  81  74  81 /   0  10  10  50

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...Small Craft Should Exercise Caution until 7 PM CDT this evening
     for GMZ330.

     Small Craft Should Exercise Caution through Saturday evening for
     GMZ350-355-370-375.

&&

$$

SHORT TERM...Adams
LONG TERM....24
AVIATION...Fowler
MARINE...24