Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Houston/Galveston Texas
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 diffluence 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.
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 55 77 49 60 / 20 20 10 10 10
Houston (iah) 72 56 75 54 62 / 20 40 20 10 10
Galveston (gls) 66 58 71 57 62 / 30 60 20 10 10