Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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FXUS64 KHGX 241759
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1259 PM CDT Sat Jun 24 2017

.AVIATION...
Majority of convection has shifted west of the Interstate 45
terminals early this afternoon, with strongest TSRA focused along
a frontal boundary stretching from near 11R to UTS to LFK and an
outflow boundary from near VCT to LBX to GLS. TSRA along these
boundaries may impact all but the Houston terminals through mid-
afternoon, with visible satellite showing cirrus debris from this
mornings storms beginning to show some thinning across the Houston
metro. This continued heating may result in an isolated TSRA
developing near the Houston terminals through the evening hours.
Frequent amendments are anticipated as convective trends become
established. Have low confidence in timing for convection
tomorrow, but with precipitable water values hovering around 2
inches and convective temperatures in the low to mid 80s expect
another round of daytime SHRA/TSRA focusing along remnant
boundaries form today.

Winds will be variable 5-10 knots, especially in the vicinity of
these aforementioned boundaries or within TSRA, with areas that
see clearing this afternoon possibly experiencing some 20-25 knot
gusts from mixing. Northerly wind shifts are possible if one of
the aforementioned boundaries moves across a TAF site, with the
most likely location to experience one of these wind shifts in the
short term being Galveston by 19-20Z. Expect winds to become
generally east to northeast overnight and through the remainder of
the TAF period.

VFR conditions are expected outside of TSRA but deterioriations to
LIFR will be possible in stronger storms from heavy rainfall. A
brief window of MVFR ceilings will be possible Sunday morning.

Huffman

&&

.PREV DISCUSSION... /ISSUED 1001 AM CDT Sat Jun 24 2017/

DISCUSSION...
Bumped up PoPs in the update this morning, to account for
the large swath of showers and thunderstorms that have resulted
from the collision of two boundaries this morning. One boundary
which has moved in from the northeast, and the other that has
pushed northward from the south which originally formed near the
coast. These storms will continue to produce localized flooding
due to heavy rainfall, and higher rain rates can be expected
within some of these storms. Also tweaked temperatures slightly to
account for current observations, keeping us a one or two degrees
cooler due to cloud cover.

Hathaway

PREV DISCUSSION... /ISSUED 627 AM CDT Sat Jun 24 2017/

AVIATION...
Complicated and messy forecast today. Patchy fog and some low cigs
have settled around SE Texas this morning. At the same time, a
broken line of thunderstorms is pushing southwestward through the
northern taf sites right now while scattered showers and storms
continue to develop near the coast and push northward into the
southern half of the taf sites. Model consensus is generally that
periods of showers and thunderstorms will be ongoing for today and
into this evening, but overall timing trends are very hard to pin
down. Other than the initial convection happening right now, the
tafs have VCTS wording pretty much all day and amendments will
likely be needed to better pin down the timing as things progress.
Vis and cigs should gradually improve to VFR other than right
inside thunderstorms this afternoon with some possible MVFR cigs
and patchy fog developing again overnight tonight.  11

PREV DISCUSSION... /ISSUED 449 AM CDT Sat Jun 24 2017/

DISCUSSION...
Precip along a long lived ssw moving outflow has combined with
another line of shra/tstms moving swd across north Texas. This
line is currently moving into southeast Texas ahead of
schedule/forecast. Assuming it maintains about the same motion,
it should be situated from roughly Brenham to Houston to Winnie by
around 8am. Speed convergence along the coast is contributing to
additional (and increasing) precip development along the coast.
The threat of localized heavy rain will occur should this continue
to fill in and collide/merge with the incoming precip from the
north later this morning. We`ve included the mention of heavy
rain in the grids for areas generally along/south of a Bellville
Liberty line this morning.

Not a whole lot of confidence as to what the remainder of the day
has in store. One would think we`d have a decent break in the
early to mid afternoon hours in the wake of this mornings
activity. But with 2-3.3" PW`s in place, along with low convective
temperatures, it won`t take much heating to get additional
activity to develop. Have 50% POPs in as placeholders for the
afternoon, which can be adjusted either way as trends are
established.

Southeast Texas will remain in a general weakness aloft for a good
portion of the week. Available moisture will be highest, and
convective temps lowest, areawide between now and Tuesday. Slow
storm motions are forecast, at least on the synoptic scale, as
well so we`ll need to continue to keep an eye on the localized
heavy rain potential. Timing of precip will be difficult, and much
will probably occur on a mesoscale/microscale level not modeled
well further in time. So, like this afternoon, a lot of the POPs
and timing are broad brushed and will be refined with near term
trends.

Gradually lowering moisture levels, especially inland, are
expected during the second half of the week. So we`d generally
expect warmer conditions and less precip coverage then. Medium
range solutions do try to gradually build the eastern ridge back
overhead next weekend. 47

MARINE...
A SCEC is in effect through 9 AM this morning as winds will be at
least gusting to over 15kt through around mid morning. Winds and
seas will continue to diminish over the weekend before ramping up
again beginning mid week as the gradient tightens in response to a
developing surface cyclone over the lee side of the Rockies.

Tides remain slightly elevated this morning and are running about
1.5 feet or so above normal. A Beach Hazards Statement is in effect
through noon today as these tide levels and wave run up will likely
cause some water to wash over Hwy 87 on Bolivar around high tide
this morning. These conditions will also likely cause strong rip
currents and longshore currents along Gulf-facing beaches today.
With winds and seas gradually diminishing, tide levels should
improve heading into this weekend.  11

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      73  87  71  88  72 /  50  50  40  40  20
Houston (IAH)              75  87  72  87  72 /  40  50  40  60  30
Galveston (GLS)            79  87  78  86  77 /  30  50  40  60  40

&&

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

$$

Discussion...08
Aviation/Marine...14


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