Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 271124
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
624 AM CDT Mon Jun 27 2022

.AVIATION [12Z TAF Issuance]...

Outside of showers and storms today, VFR conditions will prevail.
Winds will be light and variable throughout the day, but
occasionally northerly in the wake of a weak cold front passing
through this morning. Isolated showers and storms possible south
of IAH and east of I-45 through the early afternoon due to an
upper level low hovering near the TX/LA border. However, coverage
of this isolated precip did not warrant VCSH or VCTS until the
early afternoon. By 18Z, convection becomes more widespread near
the coast, so added VCSH for LBX and GLS. Then with more daytime
heating, VCSH transitions to VCTS for coastal sites. By 20-22Z,
coverage of precip increases further and we can expect scattered
showers and storms for most sites, especially south of CXO.
Therefore, by 21Z, most sites will have VCTS until 02Z when these
storms dissipate with the loss of daytime heating. By 06Z, the
front and upper level low will push offshore, but isolated showers
possible near the coast during the overnight hours for LBX and
GLS.

Lenninger

&&

.PREV DISCUSSION /Issued 426 AM CDT Mon Jun 27 2022/...



.SHORT TERM [Today Through Tuesday Night]...

A weak cold front will reach the coast this morning and an easterly
moving mid level shortwave over LA will continue to push along the
Gulf coast. Therefore, with most of the support remaining near the
coast, best precip chances remain south of I-10 through the early
afternoon with 20-30% PoPs. Despite broken to overcast cloud cover
throughout the day, temperatures will reach the mid 90s which should
be warm enough to reach the convective temp. Hi-res models are
hinting at showers and storms quickly growing in coverage by 21Z
coinciding peak daytime heating. Most coverage will be along the
diffuse frontal boundary, draped somewhere near I-10 and the coast as
well as the mid level shortwave located in our southeastern coastal
waters. Overall, best rain chances will be west of I-45 and south of
Conroe. By midnight tonight, the front will push offshore and the
remnant shortwave will still be lingering in our coastal waters.
Therefore, slight rain chances can be expected near the coast during
the overnight hours.

Afterwards, the forecast gets a little tricky as most CAMS and
global models are hinting at a broad surface trough developing in
the Gulf somewhere between 50 miles and 150 miles southeast of
Galveston near the mid level shortwave. Given it`s broad and weak
organization, it`s placement will determine our rain chances and
rainfall amounts. Since the trend the past few days has been to push
this surface trough further south, rain chances have also pushed
further south and have begun to taper off for our CWA. Despite that,
kept 30-40% PoPs mainly around I-10 and south through Tuesday
evening. Between now and Tuesday evening, we can expect upwards of
an 1.0 inches of rain south of I-10 and upwards of 0.5 inches north
of I-10, but localized higher amounts are possible.

With ample cloud cover today and tomorrow, daytime highs will reach
the mid 90s today and low 90s tomorrow. Overnight lows will still
reach the mid to upper 70s.


.LONG TERM [Wednesday through Sunday Night]...

The main forecast challenge and concern during the long-term period
revolves around the potential development and track of a sfc trough
along the TX coast. Southeast TX will be positioned between the
southeastern edge of an upper ridge centered over the Southwest
CONUS and a trough over the NW Gulf by midweek. At the sfc, a
quasi- stationary boundary extending along the coast will continue
to act as the main focus for increasing moisture and instability
over the region. Showers and thunderstorms will be ongoing or can
be expected, mainly south of I-10 with the highest chances along
the islands and coastal waters. The forecast gets "tricky" later
Wednesday as most of the activity will strongly depend on the
development of the aforementioned trough and the location of the
stalled front. At this point, uncertainty in the evolution of
this trough remains very high given run-to-run model
inconsistencies. Latest GFS, ECMWF and NAM still bring an area of
low pressure developing along the Middle TX coast (a bit farther
south of our region) by early/midweek. However, models are still
in disagreements regarding timing and strength. The upper ridge
to the west will strengthen a bit (from 591 to 594dm) on
Wednesday, helping to keep this trough along the TX coast. The
ridge slightly weakens and expands northward later on Wednesday,
possibly opening the door for this trough to move WNW farther
inland on Thursday. Having said that, deep tropical moisture will
remain in place during the period, triggering rain/storm chances
either along the stalled front or the sfc low. Global models
suggest an increase in moisture late Wednesday into Thursday with
PWATS around 2.0+ inches. Have continued with PoPs from 40 to 70
percent along the islands/coastal waters, decreasing into 20 to 40
percent as we move farther inland. Best precipitation chances
Wednesday and Thursday.

The forecast looks even more uncertain Thursday and beyond since it
will depend on the final outcome of this trough and/or sfc boundary.
Have kept low precipitation chances at 35 percent or less through
the end of the long term period.

Clouds and precipitation will lead to near to slightly above
normal temperatures throughout the week; at least for areas south
of I-10. Highs will be in the 90s. Warmest readings can be
expected north of I-10, which is where less PoP/clouds can be
anticipated.

05


.MARINE....

A weak front will move over the coastal waters early this morning
and stalls along the coast through most of the week. In addition, a
weak disturbance over LA will continue to move west-southwest today,
increasing precipitation chances over the coastal waters. With that
being said, isolated to scattered showers and thunderstorms can be
expected today with increasing chances tonight and Tuesday.
Unsettled conditions remain through most of the work-week as the
aforementioned front stalls and an area of low pressure develops
over the northwestern Gulf. Uncertainty in the evolution and
track of this low is very high; however confidence in periods of
moderate to heavy rain and scattered thunderstorms Tuesday into
Wednesday is increasing. The development of this low pressure
system will result in elevated winds and seas as the system tracks
westward into the Middle/South TX coast.

05

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  96  75  94  74  95 /  50  30  20  10  20
Houston (IAH)          94  77  91  77  91 /  30  30  30  30  30
Galveston (GLS)        92  81  89  82  87 /  50  50  40  50  60

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...None.

&&

$$

SHORT TERM...Lenninger
LONG TERM...05
AVIATION...Lenninger
MARINE...05


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