Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
FXUS64 KHGX 250912
Area Forecast Discussion
National Weather Service Houston/Galveston TX
412 AM CDT SAT JUN 25 2016
Latest radar trends show some shower and isolated thunderstorm
activity in the Gulf off the Upper Texas Coast. Most of this
activity seems to be dissipating as it moves inland. Upper air
analysis from 00z soundings show an upper level low over northern
Mexico just west of the Rio Grande. An upper level ridge was
located mainly over LA/MS. SE Texas will fall within a zone of
large scale ascent to the west and subsidence to the east. Higher
moisture axis is expected to develop through C Texas today. The
00z CRP/BRO soundings show precipitable water values of 1.8-2
inches. With most of the area falling between rising motion and
sinking motion in the atmosphere, think that at least some widely
scattered showers and storms will develop today with day time
heating. A few of the storms could produce some higher rain rates.
Overall, the forecast will go with 40 PoPs today with higher
chances towards the coastal bend.
Sunday and Monday should be transition days with a pattern change.
The upper level low should meander around the Rio Grande before
weakening. The upper level ridge over LA/MS also retrogrades over
the S Plains and then the 4 Corners region by Tuesday. The
forecast will go with 20 PoPs for Sunday as activity should be
more isolated since there will be more influence from the ridge
than the low. PoPs increase to 30/40 percent on Monday as
northerly flow aloft develops.
Tuesday and Wednesday look to have the highest rain chances next
week. Upper level pattern becomes more favorable for convection as
the ridge will be over the 4 Corners Region with N/NW flow aloft
through the plains with a mean trough over the Great Lakes. A weak
frontal boundary may slide into the area from the NE Tuesday into
Wednesday which would support more widespread thunderstorm
activity. Precipitable water values along the front remain high
around 2 inches so there is the potential for some storms to
produce heavy rainfall. Tuesday will go with 60 PoPs and then 50
PoPs on Wednesday. Rain chances continue through the end of the
week since there is little change in the pattern. Over the next 5
days it looks like much of SE Texas will get 0.5 to 1 inch of rain
with most of that coming in the Tuesday/Wednesday time frame. As
usual, there will be isolate higher amounts likely in the 1-3
inch range. Most of the area will be able to handle that much
rainfall with out any flooding impacts.
As far as forecast confidence is concern, I would not say there is
high confidence but the models are in pretty good agreement even
in the extended range with the GFS/ECMWF solutions. Both models
show the front coming down from the NE with the change in pattern.
The model differences will always be in the exact details but
overall patterns are very similar and would expect these model
trends to continue.
Moderate Southeast winds will continue through the weekend, but
decrease early next week as the surface high pressure ridge
expands over the northern Gulf of Mexico, resulting in a loosened
pressure gradient. Three foot seas this weekend will decrease to
one to two feet by early next week. Isolated to scattered showers
and thunderstorms will continue for the next several days. Rain
chances will improve Tuesday afternoon into Wednesday as an upper
level disturbance moves across the area from the North to South.
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 93 75 94 75 94 / 40 10 20 10 30
Houston (IAH) 93 76 94 75 95 / 40 10 20 10 30
Galveston (GLS) 89 82 89 80 89 / 30 10 20 10 30