textproduct: Houston/Galveston

SHORT TERM

(This evening through Thursday Night) Issued at 342 PM CDT Wed Apr 2 2025

Water Vapor imagery currently shows an broad upper level trough over the Southwest CONUS, with a shortwave trough downstream currently filling across the Northern Plains/Upper Mississippi River Valley. These two features should serve as the main driver of active weather across much of the CONUS over the next several days. For today, the shortwave will be the main feature of focus, with it's deep surface low tightening the pressure gradient and establishing a 40-60 knot LLJ over much of the Mississippi River Valley for today. Gusty winds reaching 25 to 35 mph continue this afternoon with a Wind Advisory in effect through 7 PM.

As the shortwave & surface low track northeasterly, it'll slowly push a cold front into the vicinity. Right now, that front is moving through the Dallas/Fort Worth area, but high resolution guidance suggests it will slow and eventually stall out over portions of the Brazos Valley later this evening. Showers are currently developing north of the I-10 corridor and the environment is showing some favorable ingredients for the development of stronger storms this afternoon. SPC mesoscale analysis shows 30-60 knots of 6km bulk shear in place with ML CAPE reaching around 2500-3000 J/KG. ML CIN is around -25 to -100 J/KG presently, but HREF members have suggested that it could fall to -10 to -50 J/KG across our northern counties later this afternoon. Midlevel lapse rates range from 7.5- 8.5 degC/km with forecast soundings showing modest instability in hail growth zone. In addition, these soundings are also show drier midlevels with TEI values near 25. 3km SRH ranges from 150-250 m2s2, though HREF members suggest that this will be decreasing over the next few hours. HREF Updraft helicity paint balls greater than 25 m2/s2 keep north of our CWA though this afternoon, and given lacking upper level forcing, it may prove difficult for these storms to organize.

SPC currently has our northernmost counties under a Marginal (level 1/5) Risk of severe storms today. All severe hazards are on the table, though damaging wind gusts and large hail will be the main hazards. The severe weather threat comes to an end later this evening with the loss of daytime heating.

Thursday will see relatively similar conditions to that of today. While the pressure gradient briefly weakens overnight, the aforementioned broader trough over the Desert Southwest will spin up another surface low over the Rockies, tightening the pressure gradient again and reinvigorating the LLJ for Thursday. This means another day of gusty winds reaching 25 to 35 mph. As a result, another Wind Advisory will be in effect from 7 AM to 5 PM Thursday for most areas along and south of the US-59 corridor.

The parameter space for Thursday remains largely unchanged compared to today. The HREF still shows 30-60 knots of bulk shear in place on Thursday with SFC CAPE ranging from 2000-3400 J/KG in the afternoon. SFC CIN is progged to reach -10 to -50 J/KG in areas north of I-10 during the afternoon. Forecast soundings still show drier midlevels with lapse rates from 7.0-8.25 degC/km. The main differences compared to today are increased TEI values of 25-30, slightly higher 3km SRH, and greater SFC CAPE. In spite of cloudy skies, highs are forecasted to be a tad warmer, with more areas reaching the mid/upper 80s during the afternoon. With the stalled frontal boundary expected to stay north of our area, there still won't be much forcing available to aid these storms, much like today.

SPC has our northernmost counties under a Marginal (level 1/5) Risk of severe storms on Thursday as well. Once again, all severe hazards are on the table, though damaging winds and large hail will be the main concern. The severe weather threat is still very conditional, and storms could struggle to initiate due to lackluster forcing. The severe weather threat comes to an end once again Thursday evening as instability wanes.

03

LONG TERM

(Friday through next Tuesday) Issued at 342 PM CDT Wed Apr 2 2025

Western trough will dig southward across the Desert Southwest and northern Mexico Friday. Lead disturbances on Friday should mostly take a trajectory along the quasi stationary frontal boundary stretching from the Big Bend to ArkLaTex area and where better chances of rain should be situated. But heading into late Friday night & Saturday, a strong shortwave is expected to kick out and track across West Texas into the Southern Plains and the front should get a push to the south. As this occurs, we should see better shra/tstm chances across the region and will need to keep an eye out for some embedded stronger cells. The front should track thru the area during the day Saturday and off the coast Saturday evening. Suspect the front will take the majority of available moisture with it, but some guidance is showing the trailing trof axis not fully making it past the area til late Monday. Regardless, we should see some much cooler wx filter into the area behind the frontal passage (40s/60s-70s) into early next week followed by a slow warming trend (~50/80) toward midweek. 47

AVIATION

(06Z TAF Issuance) Issued at 1144 PM CDT Wed Apr 2 2025

MVFR conditions will continue into Thu and some locations may lower to IFR at times during the overnight to early morning hours. Coastal areas may have some reduced vis due to patchy fog during the overnight to morning hours. There may be some periods when clouds scatter out a bit during in the afternoon, however, the low BKN/OVC ceilings should return Thu night. S-SE winds at around 08-15 KTS expected tonight with gusts of around 20 KTS on occasion. Winds will strengthen again to 15-22 KTS with gusts of around 25-30 KTS Thu morning as the llvl jet strengthens again.

24

MARINE

Issued at 342 PM CDT Wed Apr 2 2025

A long fetch of 20-30kt south-southeast winds has set up across the western Gulf and are producing 6-10ft seas. This will continue (and probably increase another few feet) through at least Saturday morning and Small Craft Advisories are in effect. Winds will generally inhibit the dense fog potential, but mariners can also anticipate some minor coastal flooding along Gulf-facing beaches around times of high tide (this includes the lowest more- prone spots like HWY 87/124 along the Bolivar Peninsula, Western Galveston Island, Bluewater Highway and Surfside). Chances for showers and storms will increase ahead of a strong late season cold front expected to push off the coast Saturday afternoon or evening. 47

PRELIMINARY POINT TEMPS/POPS

College Station (CLL) 74 88 74 88 / 10 20 20 50 Houston (IAH) 75 89 75 86 / 10 10 0 20 Galveston (GLS) 73 79 73 79 / 10 0 0 10

HGX WATCHES/WARNINGS/ADVISORIES

TX...Wind Advisory from 7 AM to 5 PM CDT Thursday for TXZ178-179-199- 200-213-214-226-227-235>238-300-313-335>338-436>439.

Beach Hazards Statement through late Thursday night for TXZ436>439.

GM...Small Craft Advisory until 4 AM CDT Friday for GMZ330-335-350- 355-370-375.