Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 301145
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
645 AM CDT Thu Jun 30 2022

.AVIATION [12Z TAF Issuance]...

Showers and thunderstorms are moving their way onshore this
morning impacting LBX, GLS, SGR, and HOU. Coverage of these storms
will expand northwards through the day to IAH and possibly CXO.
The storm activity will diminish this evening inland, but may
persist at the coast through the entire day near GLS and LBX. More
widespread showers and thunderstorm move in from the coast around
midnight tonight bringing SHRA to LBX and GLS. The precipitation
coverage will expand northwards through the night to SGR/HOU by
9-10z, and then to IAH/CXO by sunrise. Precipitation will persist
for most of the day on Friday along and south of I-10 with
scattered showers lingering on Saturday. Periods of heavy rainfall
are possible tonight into Friday resulting in lowering
visibility. MVFR CIGs if 1500-2500ft will begin tonight along with
the rain showers. South to southeasterly winds will persist
through the period.

Fowler

&&

.PREV DISCUSSION /Issued 417 AM CDT Thu Jun 30 2022/...

.SHORT TERM [Through Friday Night]...

This short term period will be the wettest short term period we have
experienced in quite some time thanks to the surge of tropical
moisture from Invest 95L making its way into SE Texas. This system
is currently located down off the South Texas coast and will be
sliding up into SE Texas tonight into Friday morning. There is a
medium percent chance of development for this system into a short
lived tropical depression, but whether or not it does will not
change the expected impacts. But first we have some of the typical
nocturnal showers and thunderstorms developing over the coastal
waters this morning. This activity will move onshore around
sunrise bringing some early rumbles of thunder across the coastal
counties like yesterday. A very brief lull in thunderstorm
activity between sunrise and the midmorning before the return of
thunderstorms moving up from the coast. Afternoon heating will
help expand the precipitation to most areas south of Conroe.
Expecting scattered coverage like yesterday, so you may experience
nothing or up to an inch of rain depending on where exacting
those storms develop. Those scattered storms will diminish after
sunset, but the main surge of precipitation from the low pressure
system to our south arrives overnight tonight.

The onset of the potential heavy rain tonight may start between
midnight and 3am across the coast, and then up towards the US-59
corridor between 3am and sunrise on Friday. Deep moisture profiles
(saturated up to 400-500mb with PWATs around 2.3") support
rainfall rates of 2-3" per hour for stronger embedded storms
within the more widespread rainfall (0.25" to 0.5" per hour
rates). The 1 and 3 hour FFG for the coast is between 4 and 5"
thanks to the drought conditions, so not expecting any widespread
or major flooding issues. But if there is any training of storms,
then low lying areas and areas of poor drainage could experience
some minor flooding issues (thinking more flood advisory type of
stuff versus flood warning). WPC has placed Harris County and
areas south and east of Harris County in a Slight Risk for
Excessive rainfall for tonight and Friday. The potential for
locally heavy rainfall will persist through the day on Friday,
though there will be a very sharp cutoff of precipitation. Areas
north of Harris County may see very little rainfall through the
short term while areas along the immediate coast may experience 3
to 6" with locally higher amounts to 8". There is a high "bust"
potential with these higher rainfall totals due to this sharp
cutoff and it all depends on where exactly the low pressure system
tracks. With weak, unorganized systems like this disturbance
guidance will struggle on the exact locations. If it ends up
tracking further offshore, then all the heavy rain will stay off
shore. If it ends up sliding more inland, then the heavy rainfall
will follow suit. The most likely scenario though is that portions
of coastal Matagorda, Brazoria, Galveston, and Chambers counties
may get those higher rainfall totals.

By Friday evening, expecting the rain to end west of Harris County
with lingering showers and thunderstorms persisting for
Galveston, Chambers, southern Liberty, and eastern Harris
counties. Precipitation will expand in coverage across the
northern portion of the region on Saturday, but more on that in
the Long Term below. With this rainfall, hopefully we can make a
dent in the drought conditions.

Temperatures through the short term will be closer to seasonal
during the daytime hours thanks to cloud cover. For today, expect
highs in the low to mid 90s north of Conroe, upper 80s to low 90s
along the I-10 Corridor, and mid to upper 80s along the coast. With
the rainfall tomorrow, expect temperatures to stay in the 80s area
wide. Overnight lows will remain on the mild side with temperatures
in the mid to upper 70s.

Fowler


.LONG TERM [Saturday Through Thursday]...

Dense tropical moisture associated with 95L will linger over the
region into Saturday. Therefore, much of the CWA can expect another
day of beneficial rainfall. Locally heavy showers and thunderstorms
are expected to occur considering precipitable water values are
likely to exceed two inches over much of the region. Beyond
Saturday, the heat becomes the primary story once again.

A large building ridge of high pressure will dominate our weather
next week. PoPs will decrease as temperatures become progressively
hotter as 500 mb heights build into the 592-596 dm range. There will
be a risk of isolated diurnal showers and thunderstorms. However, I
wouldn`t count on the atmosphere watering your lawn next week.
Conditions are likely to remain quite dry for most locations,
especially once we reach Monday and beyond.

Despite being dry rainfall wise, dew points are unfortunately
looking to be quite high. Heat index values could approach heat
advisory levels (108F) starting on Monday. Drinking plenty of
water will be a must for anyone planning to spend their 4th of
July holiday outside. Temperatures are expected to slowly inch
upward as the week progresses. Most of the latest model guidance
is indicating very little in the way of dry air mixing down to the
surface during the heating of the day. This suggests that heat
index values will be increasing as well. I hope you like water
cause you are going to need it!

Self


.MARINE...

The National Hurricane Center continues to monitor a disturbance in
the Western Gulf, with a medium chance of this system developing
into a tropical depression today as it pushes westward before
advancing inland along the Middle TX coast tomorrow. Regardless of
the system`s classification as a tropical depression or lack
thereof, it will produce elevated winds and seas across the bays and
coastal waters while also bringing widespread thunderstorms.
Additionally, the rip current risk along Gulf-facing beaches will be
increasing over the next few days as a result. As the system moves
further inland on Saturday, precipitation coverage will decrease and
winds and waves will begin to diminish. Light to moderate onshore
flow with 2-3ft seas will prevail well into next week.

Cady


.TROPICAL...

The National Hurricane Center continues to monitor the low
pressure system off of South Texas for the potential of tropical
development. Formation chance over the next 2 day is 40 percent
(medium). If it does form, it would be a short lived tropical
depression this afternoon/evening before it moves onshore later
tonight. Whether or not it forms will have little influence on the
expected impacts to the area with locally heavy rain along the
coast being the main concern.

Fowler

&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  95  74  88  75  89 /  30  10  50  30  50
Houston (IAH)          89  76  86  76  89 /  70  50  80  40  70
Galveston (GLS)        87  80  88  82  88 /  80  70  80  40  60

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...SMALL CRAFT SHOULD EXERCISE CAUTION through this evening for the
     following zones: Brazoria Islands...Galveston
     Island...Matagorda Islands.

GM...SMALL CRAFT SHOULD EXERCISE CAUTION through this evening for the
     following zones: Coastal waters from Freeport to Matagorda
     Ship Channel TX out 20 NM...Coastal waters from High Island
     to Freeport TX out 20 NM...Waters from Freeport to
     Matagorda Ship Channel TX from 20 to 60 NM...Waters from
     High Island to Freeport TX from 20 to 60 NM.


&&

$$


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