Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Houston/Galveston Texas
128 PM CDT Monday Mar 10 2014
issued a dense fog advisory for Galveston Bay and near shore
waters through 06z.
Coast Guard reported visibilities less than a mile at
redfish and near The Pilot station. Galveston web cams also show
fog encroaching on area beaches. 43
Previous discussion... /issued 1211 PM CDT Monday Mar 10 2014/
see 18z aviation discussion.
generally VFR conds expected through 03z. An upper low will move
east over southeast Texas between 03-09z and bring a chance of rain to
mainly the southern taf sites. LIFR ceilings are expected to develop
overnight and linger through much of Tuesday morning. Light winds
today will become SW by tomorrow morning and increase a bit on
Tuesday. VFR conds expected after 18z Tuesday. 43
Previous discussion... /issued 928 am CDT Monday Mar 10 2014/
eastern County fog is beginning to slowly lift/visibilities improve
above a quarter mile at the top of the hour so have let the dense
fog advisory expire. A mainly overcast morning with only minor
breaks in the middle-high level deck this afternoon. A thinner veil
or afternoon breaks...a light east-southeast breeze and near 1 inch precipitable waters
will make for a comfortably mild day warming into the upper 60s to
lower 70s. The bulk of the maritime and coastal County rainfall
will hold off until the evening and early Tuesday morning hours...
or when the upper trough axis comes across eastern Texas. Periods
of light rain...scattered showers...and the isolated rumble of
thunder will all end by middle to late Tuesday morning if nwp modeling
is correct and advances the trough axis over the Louisiana coastline
Tuesday afternoon. 31
Previous discussion... /issued 438 am CDT Monday Mar 10 2014/
high clouds have begun to move over southeast Texas from the west as upper
low over Mexico begins to move east. This may be a weak lead short
wave trough within the upper level flow. Areas north of this cloud
cover where skies are clear have areas of fog and some dense fog.
Right now dense fog looks very patchy so will continue to monitor
for a dense fog advisory mainly for areas northeast of a Huntsville
to Cleveland line. High clouds should limit fog southwest of that
line this morning.
Water vapor imagery shows upper low over Mexico beginning to move
east across Mexican mountains. Large scale ascent appears to be
spreading over the Rio Grande as diffulence aloft increases.
Models are all in pretty good agreement with bringing the upper
low to between del Rio and Laredo. By 12z Tuesday upper low should be
just east of San Antonio with the NAM a little farther south.
Best chances for rainfall will be from 00z-12z Tuesday or Monday night.
Significant rainfall will remain off the coast in the Upper Texas
coastal waters of the Gulf. Probability of precipitation of 60/70 percent still looks
reasonable for the coastal counties but there will likely be a
sharp gradient between rain and no rain. Interstate 10 may be that
cut off point so higher rain chances exist south of I-10 with only
slight chances north of I-10. Forecast will mention showers and
isolated thunderstorms but really think any thunderstorm activity will
be in the Gulf where coastal low may form in response to the
strong vertical motion with the upper low. Rain chances should end
Tuesday afternoon with the system moving east and highest rainfall
totals along the northern Gulf Coast and miss Delta.
Models still in good agreement with next frontal passage for Wednesday
morning. Best cold advection does not occur until 18z when 850mb
temperatures begin to drop. Will limit maximum temperatures on Wednesday to the low 60s
which is a couple degrees below guidance. Otherwise guidance
numbers look fairly reasonable for the end of the week. Thursday still
looks to coldest of the days with min temperatures back in the 30s/low
40s. Return flow then sets up Friday through Sat. Both the GFS/European model (ecmwf)
have good agreement for the weekend pattern so have some 30 probability of precipitation
for Sunday or day 7 of the forecast. Both models show a potent
upper level low moving into c Texas late sun. Pattern looks to be
favorable for severe weather in the warm sector which would set up
over southeast Texas so this time frame will have to be closely monitored. 39
northeast winds this morning will become more easterly this
afternoon as an area of low pressure continues to develop across
the western Gulf of Mexico. This surface low will shift eastward
on Tuesday bringing west winds to the coastal waters. A strong
cold front will move offshore Wednesday morning with advisory
conditions likely in its wake. Onshore flow will then redevelop by
Thursday evening and persist into the weekend. 38
Preliminary point temps/pops...
College Station (cll) 73 53 76 50 57 / 10 20 10 10 10
Houston (iah) 72 54 75 55 62 / 10 40 20 10 10
Galveston (gls) 67 58 71 58 62 / 20 60 20 10 10
GM...dense fog advisory until 1 am CDT Tuesday for the following
zones: Galveston Bay...waters from High Island to Freeport
out 20 nm.