Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Houston/Galveston Texas
347 PM CDT Sat Jul 12 2014
a deep layer high pressure ridge was over southeastern Texas this
afternoon. The models forecast the ridge to slowly recede westward
over the next few days. A weak upper low is expected to affect the
area on Sunday with the high briefly re-establishing itself on
Monday before continuing to weaken. For the middle and latter
part of the upcoming week...a late season cold front is forecast
by the models to sink southward into the northeastern portion of
The main forecast item of the next few days will be daytime high
temperatures. These are expected to reach into the middle and upper
90s both Sunday and Monday...with Sunday probably seeing slightly
cooler temperatures due to isolated to scattered thunderstorms as
the upper level low drifts onshore the coastal areas. The models
differed a bit on the timing and coverage...and the nambufr
forecast soundings kept the best chances over the eastern and
coastal areas. Decided to tweak the rain chances to reflect the
shorter range models and to tweak the temperatures downward a bit
to reflect the probability of precipitation and weather grids.
Monday should see slightly warmer temperatures due to the upper
low dissipating or moving westward. As was previously expected...
an increase in the low-level moisture will lead to heat indices
reaching to near 105 in some locations.
For the remainder of the week...rain chances will become the main
forecast issue. The models were similar to the previous runs with
the best rain chances over the north starting on Tuesday. There is
some indications that the coverage may be more widespread on
Friday. The GFS and European model (ecmwf) both indicate increasing 850 mb winds
Thursday and Friday. If the frontal boundary sinks a bit further
to the south...locally heavy rainfall may become an issue as the
low- level jet...pw/S near 2 inches... a diffluent upper low...and
the frontal boundary will all provide the necessary ingredients.
The increasing rain chances late in the week will also correspond
to a slight cooling trend. Will like to see consensus in another
few model runs for the frontal boundary location before increasing
the rain chances any further during the late week period.
a surface ridge of high pressure will maintain a prevailing light
onshore flow over the northern Gulf of Mexico for the next few
days. The pressure gradient is light enough that we will continue
to see a diurnal landbreeze/seabreeze effect through the early
part of next week.
Several weak upper level disturbances will cross the Upper Texas
coastal waters overnight and and on Sunday however...at this
time...most models suggest that the surface ridge will limit
shower and thunderstorm development.
The pressure gradient should tighten by the middle to latter part of
next week which will produce a more moderate onshore flow by
Wednesday night...continuing in to the weekend. 44
Previous discussion... /issued 118 PM CDT Sat Jul 12 2014/
please see 18z aviation discussion...
the sea breeze has started moving inland from the coast...however
the light rain showers associated with it are being squashed in
to submission. A weak high pressure system centered over southeast
Texas should keep all terminals rain free this afternoon.
On Sunday...a weak upper level disturbance approaching from the
east combined with increasing precipitable water values will
improve our chance for precipitation...however coverage should
still be fairly spotty. Have addressed Sunday precipitation with
vcsh/thunderstorms in the vicinity until the coverage is more certain. 44
Preliminary point temps/pops...
College Station (cll) 74 97 75 99 74 / 10 20 10 10 10
Houston (iah) 76 95 75 97 76 / 10 30 10 10 10
Galveston (gls) 80 90 81 90 80 / 10 20 10 10 10