-- Discussion containing changed information from previous version are highlighted. --
794
FXUS64 KHGX 141753
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1253 PM CDT Fri Jun 14 2024

...New AVIATION...

.SYNOPSIS...
Issued at 237 AM CDT Fri Jun 14 2024

The primary weather feature of interest continues to be a broad
area of low pressure that is expected to materialize in the
southwest Gulf of Mexico by Monday or Tuesday. The primary
concern from this feature will be the potential for heavy showers
and thunderstorms during the Sunday to Thursday time frame. The
low is also expected to bring rough coastal surf and hazardous
winds/seas offshore through much of the upcoming week. The system
is being monitored for possible tropical development (please see
tropical discussion below for more details). However, the low`s
impacts to our region may end up being same regardless of tropical
development.

It is worth mentioning that there is a fair amount of uncertainty
(see tropical discussion). Therefore, it is advised that you keep
up with the latest forecast as the situation evolves.

&&

.SHORT TERM...
(Today through Saturday Night)
Issued at 237 AM CDT Fri Jun 14 2024

Upper ridging is slowly building its way eastward form the Desert
Southwest, creating a more subsident environment aloft over Texas.
As a result, we can expect a subtle shift in the character of
temperatures over the area the next couple of afternoons. Where
yesterday was near/slightly above seasonal averages, with highs
mostly in the lower 90s, with some hot spots pushing into the mid-
90s, we`ll be slightly warmer today and tomorrow, with larger swaths
of the area seeing highs in the mid-90s. Some hot spots may well
creep up into the upper 90s. On the flip side, this morning`s lows
are likely to be the coolest of this short term stretch, though
that`s only a modest cooling. Think upper 60s way up north in
Houston County, and still around 80 degrees on the Gulf Coast.
As onshore flow gradually returns, it will become vanishingly
uncommon to see the temp slide below 70 degrees.

Of course, with Houston living so much of its life in the summertime
on the edge of a heat advisory, above average temperatures instantly
bring up questions around heat headlines.
For today and tomorrow, the expectations are that the modest
increase in temperatures will mostly be offset by a modest decrease
in dewpoints. As a result, peak heat index values look to range from
just below 100 to 106 or 107 at the high end. This is beneath the
threshold for a heat advisory, but is mighty close.
Using the experimental HeatRisk tool, the area shows between minor
and moderate impacts (threat levels 2 and 3 of 5 on the HeatRisk
scale). That shows this heat will pose some threat to broad
populations, but not necessarily outside the typical historical
context. There may be a bit more danger if you plan to have a
weekend with significant outdoor exertion, however. Another
experimental tool - the Wet Bulb Globe Temperature - indicates high
risk of heat stress (level 4 of 5 on the WBGT risk scale).
Because WBGT considers not just temperature and humidity, but also
factors like wind and solar intensity, it may be a good tool for
those who will be spending significant time outdoors in open sun,
and a need for those folks to take more precaution against heat
illness.

Meanwhile, at the surface, we find ourself on the southwestern
corner of a broad surface ridge stretched across the Southeastern
US, giving us light, but generally easterly winds today. This should
filter in some modestly drier air. The impacts here won`t be big,
but should be enough to help choke off most/all diurnal shower and
storm activity. I`ve got some slight chance PoPs in the southwest
around Matagorda Bay - down here, precipitable water values look to
slide to only around 1.3-1.5 inches. But for the large majority of
the area, the next couple of days should be rain-free. Which...is
something you`ll want to appreciate given the week coming up, but
that`s something for the long term forecaster to tell you about.

&&

.LONG TERM...
(Sunday through Thursday)
Issued at 237 AM CDT Fri Jun 14 2024

The long term is looking quite unsettled thanks to an area of low
pressure that is expected to materialize over the southwestern
Gulf of Mexico early next week. A building mid/upper ridge to the
north is expected to push the low towards northeastern Mexico,
possibly moving ashore by Wednesday or Thursday. A deep surge of
tropical moisture on the east and north side of the low is
expected to bring a daily chance of showers and thunderstorms
during the Sunday to Thursday time frame. Global models are
showing very impressive PWAT values by mid-week, increasing from
1.50-2.00 inches on Sunday/Monday to as high as 3.00 inches by
Wednesday. Heavy rainfall will be a daily concern through the long
term period. Current predicted Sun-Thu rainfall totals range
from 3-6 inches along and south of I-10 to 1-3 inches farther
north. But given the PWATs suggested by the guidance, we cannot
rule out higher totals in some areas, especially during the
Tuesday-Wednesday time frame if guidance is correct about the PWAT
values. WPC currently has the southern half of our CWA in a
Marginal Risk (Level 1 of 5) for excessive rainfall on Monday. If
current model trends hold, then the excessive rainfall risk would
likely increase further by mid-week. Uncertainties exist
regarding the future track and organization of the southwest Gulf
low (see tropical discussion below). These uncertainties have
implications on next week`s weather here in southeast Texas. So
please stay informed by frequently checking the latest forecast.

The gradient between the low and an area of high pressure over
eastern CONUS is likely to result in rough surf and elevated tides
along the coast. The model blend used in our wind grids show gusts
over 30 MPH along the coast on Tuesday and Wednesday, with 20-25
MPH gusts farther inland. With such a strong and deep east to
southeast flow from the Gulf, we opted to lean towards the NBM for
our dew points. The NBM has a notoriously high bias when it comes
to dew points. But with deep tropical flow, afternoon dew points
could easily be well into the 70s. The one silver lining is that
the afternoon temperatures are expected to be a little cooler than
normal due to the clouds. After widespread low/mid 90s on Sunday,
afternoon highs may remain in the 80s for much of the week across
the CWA.

Self

&&

.AVIATION...
-- Changed Discussion --
(18Z TAF Issuance)
Issued at 1251 PM CDT Fri Jun 14 2024

VFR conditions will generally prevail through the duration of the
TAF period. A few scattered clouds will continue to persist over
the course of the afternoon, but otherwise winds will remain light
and no cig development is expected. Overnight, winds become calm
with a few high clouds remaining over the area. Periods of patchy
fog are possible, which may at times result in a window of sub-VFR
visibility between approximately 08 and 15Z. Tomorrow, light to
moderate SE winds develop in the morning with conditions remaining
VFR.

Cady
-- End Changed Discussion --

&&

.MARINE...
Issued at 237 AM CDT Fri Jun 14 2024

Light to moderate onshore winds and low seas will prevail through
early Sunday. By Sunday afternoon, onshore winds and seas will
begin to gradually build as the gradient steepens between a
developing low pressure system over the Bay of Campeche and an
area of high pressure over the eastern United States. Small Craft
Advisory conditions are possible starting as early as Monday and
continuing until as late as the end of the week. By the middle of
the week, seas could build to 7-10 feet with sustained winds
offshore averaging around 25 knots with gusts over 30 knots. For
now, our forecast keeps conditions under gale criteria. But we
cannot rule out gale conditions, or at least gusts to gale force,
by the middle of the week across the Gulf waters.

&&

.TROPICAL...
Issued at 237 AM CDT Fri Jun 14 2024

A broad area of low pressure is expected to materialize in the Bay
of Campeche by Monday or Tuesday. Global deterministic and
ensemble guidance suggest a building ridge to the north will steer
the low west to west-northwest towards northeastern Mexico,
possibly moving ashore by Wednesday or Thursday. As of 200AM CDT,
the National Hurricane Center has given this system a 40% chance
of developing into a tropical depression over the next 5 days.
Showers and thunderstorms along with gusty winds are expected to
extend well north of the low. Therefore, southeast Texas can
expect showers/thunderstorms along with gusty winds (especially
near the coast) even if the center of the low remains well to our
south and tracks into Mexico. The steepening gradient between the
low and a surface high over eastern CONUS will likely enhance an
east to east-southeast wind fetch across the Gulf, resulting in
hazardous seas, increasing rip current risks, and elevated tides.
Sunday-Thursday rainfall totals are expected to range from 3-6"
along and south of I-10, with 1-3" for areas farther north.
Locally heavier totals are possible.

It is worth mentioning that computer models often struggle with
tropical disturbances in the pre-development phase. In this case,
a cohesive disturbance has yet to materialize. Therefore, forecast
confidence will be on the low side until a more cohesive
disturbance forms. Given the uncertainty, it is strongly advised
that you keep up with the latest forecast updates.

Self

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)  94  73  95  71 /   0   0   0   0
Houston (IAH)  95  75  95  74 /   0   0   0   0
Galveston (GLS)  90  81  90  82 /  10   0   0  10

&&

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

$$

SHORT TERM...Luchs
LONG TERM....Self
AVIATION...Cady
MARINE...Self