Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Houston/Galveston Texas
1139 PM CDT Tuesday Sep 2 2014
see aviation for 6z taf issuance.
VFR conditions across the taf sites this evening. Some sites north
of Houston might go MVFR briefly tonight but should rebound
quickly after the sun rises. The chance of rain looks very slim
tomorrow. Precipitable water values fall near to slightly below average for this
time of year with middle- level ridging starting to build in to the
area. Forecast soundings also starting to show an inversion around
850 mb. Because of this have trimmed back mention of rain in tafs.
Previous discussion... /issued 822 PM CDT Tuesday Sep 2 2014/
temperatures have fallen into the lower to middle 80s inland and
storms have dissipated there. Surge of moisture can be seen coming
into Matagorda Bay region accompanied by rain showers/thunderstorms and rain given the
acars profiles don't expect these to make it far inland. Have
lowered probability of precipitation and altered the wording as well as cleared out skies
for central and northern areas at least for a few hours. Stratus
developing a possibility for the west and northwest areas as well
as patchy light fog. Forecast with less coverage expected
Wednesday as drier air overspreads the area.
Previous discussion... /issued 634 PM CDT Tuesday Sep 2 2014/
see aviation for 0z taf issuance.
mostly VFR conditions expected for the taf sites through the
issuance. Might get some low cloud development tomorrow morning
but they should quickly lift after the sun rises. Forecast
soundings for tomorrow show lower moisture values with pretty good
instability in the soundings. An upper level ridge will be
building a bit tomorrow afternoon though so think slightly less
coverage tomorrow than today. 23
Previous discussion... /issued 415 PM CDT Tuesday Sep 2 2014/
scattered rain showers/thunderstorms and rain will continue over mainly the northern half of
southeast Texas through early evening. Storms will begin to diminish with
the loss of heating. Ts Dolly will make landfall over northern
Mexico sometime this evening and only bring long period swells to
the offshore marine zones and slightly elevated tides. A flattish
500 mb ridge slowly builds into southeast Texas from the east later this
week and precipitable water values remain between 1.8 and 1.9 inches through
Friday. Despite the building ridge...500 heights never really
increase much with values around 590 dm. Convective temperatures also
remain between 88 and 90 degrees which is reachable. There really
isn't a trigger for widespread rainfall but you can't rule out an
occasional rain showers either so will maintain 20 probability of precipitation through the
Friday. On Sunday...precipitable water values increase to 2.1 inches and both the
European model (ecmwf) and GFS bring a weak boundary into southeast Texas. Ll convergence
along the boundary increases Sunday afternoon and coupled with the
high moisture content...feel rain chances will be on the rise.
Raised probability of precipitation to chance for Sunday. The upper pattern doesn't look
conducive for a front to make it into southeast Texas but both models have
been hinting at the front entering southeast Texas for the last few days. A
deep upper trough will move into the intermountain west early next
week. The ridge over Texas will amplify in response to this and
rain chances will diminish and temperatures will warm a bit. 43
based on satellite...short-lived Tropical Storm Dolly appears to be
coming onshore this afternoon. The effects of Dolly...if any...will
also be short-lived and in the form of a higher period swell across
the far offshore western waters. A brief time frame between tonight
and into early Wednesday morning of greater than 6 foot seas...a
short fuse Small Craft Advisory will be issued this afternoon to communicate this
elevated sea threat. There is a chance for some minor water run-up along
Highway 87 during the overnight hours. Overall southeasterlies will
remain at...or slightly under...20 knots through tomorrow afternoon...
weakening back to sub-caution conditions by sunset Wednesday. Weak
disturbances rotating underneath southern U.S. Ridging will occasionally
make it into the Upper Texas coastal waters. This will provide the trigger
for return widely scattered rain and isolated thunderstorms over the next
several days. 31
Preliminary point temps/pops...
College Station (cll) 94 75 95 75 95 / 50 20 20 10 20
Houston (iah) 93 77 93 77 93 / 40 20 30 10 20
Galveston (gls) 89 81 91 82 91 / 30 20 30 20 20
GM...small craft should exercise caution until 10 am CDT Wednesday
for the following zones: Galveston Bay...Matagorda Bay...
waters from High Island to Freeport 20 to 60 nm...waters
from High Island to Freeport out 20 nm.
Small Craft Advisory for hazardous seas until 10 am CDT
Wednesday for the following zones: waters from Freeport to
the Matagorda Ship Channel 20 nm to 60 nm...waters from
Freeport to the Matagorda Ship Channel out 20 nm.