818
FXUS64 KHGX 040502
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1202 AM CDT Sat May 4 2024

...New AVIATION...

.SHORT TERM...
(This evening through Saturday Night)
Issued at 407 PM CDT Fri May 3 2024

Showers and thunderstorms are continuing to work their way through
the northern half of SE Texas this afternoon. Some of these have
produced heavier downpours as they have trained across already
saturated areas, which of course exacerbates the ongoing flooding in
locations that have previously received excessive rainfall. Current
SPC mesoanalysis shows an area of deep moisture convergence north of
I-10 along with a pocket of 1000-2000 J/kg elevated CAPE. Both deep
moisture convergence and CAPE appear to trend downward over the next
few hours, which should consequently lead to a downward trend in
showers and thunderstorms. A lull in activity is expected overnight
into Saturday with isolated showers/storms possible. At this point,
any additional rainfall will only delay improvement in the current
conditions. That being said, the decision has been made to maintain
the current Flood Watch through Sunday.

Going a little deeper into the overnight hours through Saturday
morning...Hi-res guidance has been pretty spread out run-to-run as
far as what development occurs during the overnight hours. Current
thoughts are that PWAT values remain in the 1.5-1.7" range south of
I-10 and 1.3-1.5" north of I-10. 500mb analysis shows another
potential shortwave moving across SE Texas during the overnight
hours with pockets of PVA. I don`t want to lean into the 18Z HRRR
suggesting that the area will remain rain-free overnight while the
12Z HRRR brings a few showers/storms through the area...so have
compromised by keeping PoPs on the lower end, and bearing in mind
the current setup with deep moisture and repeated shortwaves.

Saturday during the day appears to be fairly inactive as most of the
activity will fire off well west of our CWA.

Saturday night into Sunday will be the primary concern for the short-
term (beginning of long-term). Another shortwave and pockets of PVA
will track east across the area late Saturday night triggering an
MCS structure. The MCS is projected to arrive along the
western/northwestern CWA as early as Sunday morning (exact timing of
arrival is more uncertain at the moment) and will move across SE
Texas during the day Sunday. At the current moment the Flood Watch
goes through 1 PM Sunday; however, this may need to be reassessed as
this next system evolves. At this time additional rainfall totals of
1 to 3 inches and isolated higher amounts will be possible late
Saturday night into Sunday.

WPC keeps much of the area (with the exception of the immediate
coast) in a Marginal Risk for Excessive Rainfall Saturday. Portions
of the Brazos Valley and Piney Woods will be in a Slight Risk for
Excessive Rainfall.

For Sunday, WPC places the majority of the area north of I-10 in a
Slight Risk for Excessive Rainfall with the rest of the area in a
Marginal Risk.

Impacts from excessive rainfall over the last few days are ongoing
and any additional rainfall will exacerbate these impacts. Please
continue to monitor the forecasts, follow instructions from local
officials, and have multiple ways to receive warnings.

Adams

&&

.LONG TERM...
(Sunday through next Thursday)
Issued at 407 PM CDT Fri May 3 2024

As mentioned in the short-term, the beginning of the long-term
period will feature a strong shortwave with an MCS that will impact
SE Texas during the day Sunday. At the surface, a weak warm front
will lift northward into SE Texas which will reinforce the warm and
moist environment. At this time, projected additional rainfall
amounts are in the 1-3" range with isolated higher amounts possible.

Once the MCS exits the region, relatively dry weather is expected
through much of the week. The forecast hazards shift from flooding
to heat. Ground moisture is expected to stick around for awhile,
and with 850mb temperatures reaching the 99th percentile
Wednesday/Thursday, the combination of heat and humidity will lead
to heat index values approaching or even reaching into the triple
digits by mid week. Daytime highs will be in the 90s with
dewpoints well in the 70s, creating hot and muggy conditions. As
mentioned in the previous forecast, these values are 5 to 10+
degrees above normal climatological values.

With recovery efforts likely continuing into next week, please be
mindful of the increasing temperatures and heat indices. Wear light-
colored/light weight clothing, drink plenty of water, take frequent
breaks, and remember to look before you lock!

Adams

&&

.AVIATION...
(06Z TAF Issuance)
Issued at 1153 PM CDT Fri May 3 2024

A much quieter night is on tap with coverage through Sat afternoon
remaining spotty as well. Moderate onshore winds are going to con-
tinue overnight and should help to keep ceilings somewhat elevated
until closer to sunrise. Winds will be strengthening a bit more as
the day progresses on Sat as CIGs mix out. S/SE winds should be in
the 6-12kt range tonight...then 12-20kts/G20-25kts tomorrow after-
noon (higher near the coast). Did add the mention of VCSH(for now)
to IAH (and CLL) as the next storm system approaches from the west
tomorrow night through Sun morning. 41

&&

.MARINE...
Issued at 407 PM CDT Fri May 3 2024

Onshore winds have remained elevated this afternoon, remaining near
20 to 25 knots. With this expected to prevail for the next several
hours, in addition to seas reaching as high as 7 feet onshore, a
Small Craft Advisory remains in effect until late this evening.
Winds will diminish somewhat heading into tomorrow, with moderate
onshore winds expected to prevail into next week. Scattered showers
and storms will be possible tomorrow, with a more widespread and
well organized line of storms arriving later on Sunday. This line of
storms could produce some strong wind gusts, as well as periods of
heavy rain.

Cady

&&

.HYDROLOGY...
Issued at 302 AM CDT Fri May 3 2024

There is ongoing river flooding over parts of Southeast Texas,
particularly along portions of the Trinity and San Jacinto rivers.
The following river points are at, or forecast to go to Major flood
stage:

- Trinity River (Madisonville): Major Flood Stage
- Trinity River (Liberty): Major Flood Stage
- Trinity River (Goodrich): Major Flood Stage
- West Fork San Jacinto (Conroe): Major Flood Stage
- West Fork San Jacinto (Humble): Major Flood Stage
- East Fork San Jacinto (Cleveland): Major Flood Stage
- Caney Creek (Splendora): Major Flood Stage
- Trinity River (Romayor): Minor forecast to go to Major
- Navasota River (Normangee): Minor forecast to go to Major
- Menard Creek (Rye): Moderate forecast to Major
- Trinity River (Moss Bluff): Moderate forecast to go to Major
- East Fork San Jacinto (New Caney): Moderate forecast to go to Major
- Peach Creek (Splendora): Moderate forecast to go to Major
- San Jacinto (Sheldon): Moderate forecast to go to Major

Remember to heed any instructions from your local officials and to
never travel through flooded areas or 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.

JM

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  70  84  70  82 /  10  20  60  60
Houston (IAH)  72  84  72  82 /  10  10  30  50
Galveston (GLS)  73  80  73  80 /  10  10  20  30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Flood Watch through Sunday afternoon for TXZ163-164-176>179-
     195>200-212>214-300-313.

     High Rip Current Risk through Saturday evening for TXZ436>439.

GM...Small Craft Advisory until 1 AM CDT Saturday for GMZ330-335-350-
     355-370-375.

&&

$$

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