Area Forecast Discussion
Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 010450
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1150 PM CDT TUE MAY 31 2016

.AVIATION...
An upper level shortwave trough has moved off to the east as seen
on the RAP40 700-300 mb streamline analysis/forecast. Another
weaker shortwave trough upstream should help bring at least slight
chances for showers and thunderstorms early Wednesday morning
around sunrise into the mid morning period. Confidence in the
model forecast is moderate at best for the first 9 hours of the
forecast.

Better chances look to occur in the afternoon. A low-level
moisture transport looks to set up from Matagorda Bay and should
aid in thunderstorm development which should then move eastward
across the terminal sites during the mid afternoon into early
evening.

40

&&

.PREV DISCUSSION... /ISSUED 917 PM CDT TUE MAY 31 2016/

DISCUSSION...
A weak outflow boundary has triggered showers and thunderstorms
this evening over the western half of the CWA. Some of the rain
was briefly heavy with some 2 inch totals in Jackson and
Washington counties. The rain shield is weakening and decreasing
in coverage as it moves east. The HRRR develops a new area of
shra/tsra along the coast but can`t find much support for that
from other short term guidance.

00z CRP sounding had PW values at 1.97 inches while LCH was 1.42
so there is quite a moisture gradient across the area. There is a
weak 850 trough over SW TX. A weak short wave trough was also
noted at 700 mb between Del Rio and Corpus Christi. 300 mb winds
show a nice split over South and Southeast Texas and upper level
winds will likely remain diffluent through Friday.

Overall trend for the night should be light rain/isolated thunder
will end by midnight with additional shra/tsra redeveloping early
Wednesday morning. Thought the 18z TT WRF initialized best
followed by the RAP. Will be cleaning up some evening wording and
tweaking temps/PoPs but overall forecast looks on track. High Pops
certainly warranted for tomorrow and Thursday as the upper low
meanders across the state.

Will wait for 00z model guidance but considering the wet
antecedent conditions...river flooding and the potential for heavy
rain beginning on Wednesday...feel a Flash FLood Watch will be
required. Not exactly sure on when to start it but think it might
be needed by 12z Wednesday. 43

Hydrology...
It appears that the Colorado River at Wharton has crested. The
maximum value was 46.91 feet and occurred at 640 PM. The river
level was at 46.81 feet at 815 PM and is slowly falling. The news
for the Brazos at Richmond is not as good. The river reached 54.21
feet at 815 PM and this is the new maximum crest value. It may
still increase further as some constrictions downstream seem to be
impeding the flow. The USGS also adjusted the gage height earlier
this evening upward by 0.13 feet. The river should be cresting
sometime tonight and then begin to SLOWLY fall. W Fork San Jac at
Humble and Sheldon continue to fall and Humble should fall to
moderate flood by midnight. 43

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      71  83  70  80  68 /  50  70  70  70  70
Houston (IAH)              72  85  71  82  70 /  30  60  50  70  70
Galveston (GLS)            77  83  77  83  75 /  20  30  40  60  70

&&

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

$$

Discussion...43
Aviation/Marine...40



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