May 2023

[Cpv17]

If you went by the iPhone Weather App you’d think it was monsoon season. 70-80% chances of rain almost every day. Shows 70% today.
NWS keeps advertising 20-30% chances.
The reality has been more like Tucson lately.

What do I think? Imma about to turn the sprinklers on.

One of the mets on 13 mentioned they think there’s a possibility those 30% rain chances for next week will go up. I personally think they will.

[Stratton20]

Based on model guidance, those chances are definitely going up

[Stratton20]

I am becoming at least a little more concerned about the possibility of a heavy rain event next week, last nights euro and this current CMC run both have a slow and i mean slow upper low making its way across the state next week, now of course amounts and the placement of where the heaviest rains will fall is still to be determined, but the pattern is their for flooding potential

[DoctorMu]

Climo would say that the next week or two are some of our most likely periods for rain in CLL during the course of the year, on average.

GFS has moved the higher rainfalls into north Texas and CMC into south Texas. We'll have a better feel for disturbances moving through the area next week by this weekend.

[don]

Another overnight MCS may be on the menu late tonight if you believe the HRRR, FV3 & GFS models.

(Sidenote: several of the global models are developing a semi warm core low in the Gulf or along the coast and move it inland into Texas next week.Such setups in the past have produced tremendous amounts of qpf from core rain events and feeder band setups.Needs to be watched if the models continue to show this feature.)

[Cpv17]

The difference between the GEFS and EPS is pretty crazy. EPS has WAY more rain over southeast TX.

[Stratton20]

12z Euro coming in extremely aggressive with rainfall totals, wow!

[Cpv17]

12z Euro coming in extremely aggressive with rainfall totals, wow!

Seems like the operationals disagree as well.

[don]

QPF differences between the EURO,GFS,& CMC models through hour 240.The EURO and CMC are more aligned with each other with both showing a slow moving semi warm core low.(the CMC actually has 2 warm core lows forming) While the GFS shows a much drier solution with precip much further north. This May could be the busiest we've seen since May 2015.

[tireman4]

000
FXUS64 KHGX 041814
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
114 PM CDT Thu May 4 2023

...New AVIATION...

.SHORT TERM...
(Today through Friday Night)
Issued at 313 AM CDT Thu May 4 2023

Short term will be getting a bit more active compared to the past
few days. Shortwave trough moving through a weakening upper level
ridge will lead to increasing cloud cover during the afternoon
today. There will be a chance of light showers in the southwestern
portion of the region during the afternoon as moisture increases in
the area. Then the first round of storms will move into the Northern
Brazos Valley as early as 5pm with additional storms possible
through the late night hours. The highest coverage of storms will
remain in the Brazos Valley area towards Lake Livingston as the cap
looks to remain in place along and south of I-10, though cannot
out rule an isolated storm breaking through the cap. The SPC has
placed Burleson, northern Brazos, and northwestern Washington county
in a Slight Risk (level 2 of 5 threat) for strong to severe
thunderstorms with a Marginal Risk (level 1 of 5 threat) for most
areas north of I-10 and down to northern Jackson County. If the
strong to severe storms materialize, then large hail and strong
winds will be the primary hazards with locally heavy rainfall
possible. Storm threat mostly ends by midnight to 2am.

High temperatures today will get into the low to mid 80s for most of
the region, but Friday will begin to feel more like Summer with high
temperatures climbing into the upper 80s to low 90s. Persistent
onshore flow will bring dew points into the low to mid 70s for most
of the area causing heat indices to rise into the mid 90s. There may
be an isolated streamer shower Friday afternoon, but Friday will be
mainly rainfree during the day. But, the next shortwave disturbance
approaches the region Friday evening bringing additional storms,
possibly strong, to the Brazos Valley. Again the cap looks to remain
in place over the majority of the region causing the storms to
dissipate as they progress through SE Texas. Low temperatures
tonight and Friday night will be in the low 70s.

Fowler

&&

.LONG TERM...
(Saturday through Wednesday)
Issued at 313 AM CDT Thu May 4 2023

An Upper level ridge should amplify across the Upper Great Lakes/
Tennessee Valley on Saturday. 1.2-1.5" PWs and shortwave energy
streaming overhead should work to bring isolated showers/storms to
SE Texas, especially during the afternoon with support from the sea
breeze. 850mb temperatures are still progged around 17-20C with
southwesterly winds aloft from a 590 dam ridge over the the Gulf of
Mexico. Highs during the day are expected to reach the upper 80s to
lower 90s with dewpoints in the lower 70s. This, in turn, should
bring heat indices in the upper 90s to lower 100s during the
afternoon hours. Sunday should see an eastward shift in the upper
level ridge with 850mb temperatures rising by a degree or so. Global
models show progs of stronger mixing Sunday afternoon, though heat
indices will still largely be in the upper 90s. Those planning to
spend time outdoors this weekend should practice heat safety, as
early season heat events can be particularly taxing on the body.
Remember to drink plenty of water and stay tuned to the forecast.

Monday will see the upper level ridge flatten as another shortwave
trough slides eastward through Texas. Southerly flow at 850mb with a
gradually decrease in temperatures at this level should lead to a
slight reprieve from the heat early next. Look for highs in the
upper 80s to lower 90s with heat indices generally in the 90s.
Weaker capping should lead to increasing rain chances through
midweek, especially on Wednesday as an upper level trough digs in
across the Great Basin/Four Corners. Models are out of phase by this
point in the forecast, so uncertainty as to how this trough will
behave remains high.

03

&&

.AVIATION...
(18Z TAF Issuance)
Issued at 107 PM CDT Thu May 4 2023

A mix of low end VFR to MVFR ceilings will continue through late
this evening with isolated light rain possible. A disturbance will
move through the region late this evening into early Friday,
resulting in scattered thunderstorms. Have only kept VCSH and VCTS
in TAFs due to low confidence in timing and coverage of any
storms. Erratic winds up to 35 knots can be expected with any
thunderstorms. MVFR to IFR conditions can be expected mainly after
midnight and will potentially persist through the end of the TAF
period. South to southeasterly winds around 10 knots can be
expected through the cycle.

JM

&&

.MARINE...
Issued at 313 AM CDT Thu May 4 2023

Light to moderate onshore flow with seas 4 feet or less are expected
through early next week. Low rain chances are expected through the
weekend, increasing through mid next week.

03

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 83 71 88 70 / 60 50 20 20
Houston (IAH) 84 72 89 72 / 20 30 20 20
Galveston (GLS) 80 74 82 74 / 10 20 20 20

&&

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

$$

SHORT TERM...Fowler
LONG TERM....03
AVIATION...JM
MARINE...03

[Stratton20]

Holy jeez… The CMC has a max bullseye of 32.4 inches in deep south texas,
no way that verifies, but still..
I know its the CMC but it has had its moments, did pretty well with Imelda and the amount of rain it dumped

[jasons2k]

NWS still hasn’t budged.
20% overnight and tomorrow. 20-30% next week as well.

Weather app still monsoon with 70% tonight, 40% tomorrow, 70% Saturday, 70% Sunday, and 40/50/60% on various days for the rest of the 10-day.

The NWS is significantly drier than whatever model blend Apple is using.

[Cpv17]

NWS still hasn’t budged.
20% overnight and tomorrow. 20-30% next week as well.

Weather app still monsoon with 70% tonight, 40% tomorrow, 70% Saturday, 70% Sunday, and 40/50/60% on various days for the rest of the 10-day.

The NWS is significantly drier than whatever model blend Apple is using.

The CPC forecast looks a good bit wetter than what the NWS shows.

The NWS is probably waiting on the GFS to hop onboard before they increase chances. Not enough confidence yet.

[Cpv17]

The 12z EPS has the strongest signal yet for southeast TX. It’s showing 4”- 5.5” across the area over the next two weeks. That’s a strong signal for an ensemble.

[Stratton20]

Cpv17 cant remember the last time ive seen that strong of a signal and amount of rain on an ensemble

[Ptarmigan]

Holy jeez… The CMC has a max bullseye of 32.4 inches in deep south texas,
no way that verifies, but still..
I know its the CMC but it has had its moments, did pretty well with Imelda and the amount of rain it dumped

That is without a tropical system on top of it. I wonder how CMC forecasted that amount.

There was the May 2016 flood around Brenham that dumped over 20 inches of rain.
https://www.khou.com/article/news/local ... -250844170

[Ptarmigan]

This could get interesting. May has had many weather events in the past.

ENSO has gone nuts. Full bore El Nino.

Rain in CLL for summer? More mudslides It beats mega fires.

I know in the best, when El Nino is developing in the spring, it is usually wet.

[Ptarmigan]

QPF differences between the EURO,GFS,& CMC models through hour 240.The EURO and CMC are more aligned with each other with both showing a slow moving semi warm core low.(the CMC actually has 2 warm core lows forming) While the GFS shows a much drier solution with precip much further north. This May could be the busiest we've seen since May 2015.
Screenshot 2023-05-04 at 15-09-19 Models ECMWF Hi-Res — Pivotal Weather.pngScreenshot 2023-05-04 at 15-09-10 Models GDPS — Pivotal Weather.pngScreenshot 2023-05-04 at 15-09-28 Models GFS — Pivotal Weather.png

Most the heavy rain events in May 2015 were from mid to late May. The Memorial Day Flood comes to mind.

[DoctorMu]

Welp. Less rain. More humidity. Thanks.

NWS really back off a storm coming in from the west tonight...

Heat, too. Big early Suck Friday through Tuesday with highs near 90°F.

[jasons2k]

I’ll be surprised if we get anything overnight. It’s starting to dry up around here.