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Texas A&M forecast data: http://www.met.tamu.edu/t2k/
|Forecast discussion, Tue., Aug. 22,
Winds again are on the weak side at the surface this morning,
with a land breeze evident along Galveston Bay. Winds further south
in Texas City and Galveston are stronger out of south, indicating
that the land breeze is localized over Galveston Bay only. Profiler
data shows winds are stronger aloft (20-30 kts from 0.5 to 3 km),
and they are more easterly than yesterday (from ESE). I expect the
same evolution of winds as in the past few days, with the exception
of them being more easterly light/calm in morning, picking up from
the southeast near noon, with sea and bay breezes along coasts
developing by noon or 1 p.m.; east-southeast winds during the middle
and late afternoon. Looking at the background levels, Galveston is
quite high with a 63 ppb and Texas CIty is reporting 32 ppb of
ozone. With the land breeze over Galveston Bay, a return flow event
of early morning emissions will cause ozone levels to be quite high
this morning. By 1 p.m., ozone levels of 140-160 ppb (hourly
averages) are probable along Galveston Bay and the Houston ship
channel. This morning's LCH and CRP soundings, along with higher
surface dewpoints, suggest that thunderstorms will develop along the
early afternoon gulf/sea breeze. Chances that a thunderstorm will
occur over the surface observing network is 60%. Therefore, it will
be an early show for high ozone values. By 1 p.m., thunderstorm
development, increased vertical mixing, and higher wind speeds at
the surface will help to dissipate the plume.
Max T 97-99 F (37 C)
Clouds scattered cumulus early, building to broken stratocumulus
by late morning, and scattered towering cumulus/Cb this afternoon.
Anvils from the convection will stream to the west and
west-northwest, building a broken ceiling aloft by evening.
Quick Look at Tomorrow
Roughly similar to today. Light winds overnight will change to
east-southeasterly winds by afternoon. Because of mixing that will
take place today, expect ozone levels to be lower tomorrow (due to
lower background levels). Thunderstorms again are likely to develop
along the sea breeze by early afternoon.
A ridge building over the southeastern US will bring unsettled
weather with possible widespread showers. Prevailing winds will be
from the east-northeast. Dirtiness of air mass will depend upon
extent of upstream and local showers, but it could be quite dirty.
Lighter large-scale winds than in the past few days would favor high
ozone. The urban plume would be advected toward the northwest, most
likely toward Austin. By Monday, a watchful eye must concentrate on
the path of Hurricane Debby. Currently, the strength of the high
over the SE US, combined with the lack of any strong shortwave
approaching in the models, leads me to suspect that Debby could very
well visit the Gulf by early next week.
Forecaster Karl Schulze