Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Houston/Galveston Texas
630 PM CDT Tuesday Aug 4 2015
00z taf discussion in aviation section.
radar still shows a few showers west of Houston bu tshould not
impact any terminals the rest of the evening. Models hint at
possible MVFR/IFR ceilings for several areas but think this is too
aggressive. Hint at possible lower stratocu decks in the morning
in tafs but not seeing a set up for prevailing lower ceilings. Precipitation
water values look to go down a bit tomorrow to 1.8 inches. May
still see a few showers but still low enough confidence to leave
out any mention in tafs.
Previous discussion... /issued 338 PM CDT Tuesday Aug 4 2015/
a very weak frontal boundary and a sea breeze moved inland earlier
today. A more moist airmass was reflected by precipitable water/S up to around 2.0
inches as seen on the Storm Prediction Center rap output. In addition to the surface
boundaries...the nam12 and rap13 both showed weak vorticity
advection moving overhead of the forecast area. This combination
has generated isolated to scattered showers and thunderstorms. Am
expecting the activity to diminish around sunset.
Regarding rain chances for Wednesday...the middle and upper level
ridge is forecast by the models to continue building overhead.
Even so...the nam12 and high resolution models show isolated rain
chances during the afternoon. Since the models have been
consistent over the past couple of days...decided to go with a 15
percent rain chance and mention isolated showers and thunderstorms
possible during the afternoon associated with the sea breeze. Rain
chances will diminish for the rest of this week and into Monday of
next week as the upper level ridge builds over the state.
The main issue through the upcoming weekend will be the building
hot and humid airmass. The guidance and raw model output were
forecasting actual daytime high temperatures over the inland
counties as high as 99 to 102 in some places well inland through
Saturday. The heat index may reach 103 to 108 over some locations
on Wednesday and Friday...and then may possibly exceed 108 Friday
and Saturday. Will continue to monitor the model trends as the
kept mention of precipitation for most sites for the rest of this afternoon given
the trends. Models indicating that these high precipitable waters (just over 2") to
persist through tomorrow afternoon so we could see a repeat of today. Brief
MVFR ceilings noted for some sites this morning. 41
not a lot of changes with afternoon forecast package for the marine zones as
the current weather pattern remains in place. The light/moderate onshore
winds will persist with diurnal variations. Isolated/widely scattered possible
early tomorrow given the lingering deeper moisture. 41
Preliminary point temps/pops...
College Station (cll) 77 99 77 100 77 / 10 10 10 10 10
Houston (iah) 78 97 79 98 79 / 10 20 10 10 10
Galveston (gls) 83 92 83 91 83 / 10 10 10 10 10